Method and System for Precluding Air Pollution in Industrial Facilities

Abstract

A holistic system for sustained capture, confinement and depuration of acid mist generated in nonferrous metal electrodeposition processes utilizing lead anodes, for precluding zero release of gaseous fluid pollutants in the atmospheric air surrounding electrodeposition processes, providing an assured solution to acid mist control and total abatement in an effective, efficient manner and sustainable in time by immediate recovery and recycling back in the source generating the contaminant effluents as there are produced, according to a “cell by cell” strategy, and directly connecting each cell to a system for depuration, recovery and recycling the contaminants gaseous fluid flow extracted from each cell reducing them to innocuous levels in the discharge to the open atmosphere; complying the condition of “100% Null escape of acid mist” from each individual cell to the working environment, simultaneously with minimum power usage, and substantial global gaseous fluid contaminant reduction, far exceeding present minimum sustainability standards, in terms of human health, energy usage and environmental protection.

Description

FIELD OF THE INVENTION

The invention relates to a method and system for precluding release of gaseous fluid pollutants in the atmospheric air surrounding industrial processes, more specifically, the invention is a method and system for capturing and eliminating acid mist generated by the process of electrodeposition of non-ferrous metals with insoluble anodes and impeding polluted gaseous fluids and/or air from the process to escape to the working ambient air.

BACKGROUND OF THE INVENTION

Many industrial processes release gaseous fluids with contents of chemicals/pollutants to the air, which require drastic measures for carrying out these processes to avoid harm to the workers in the facilities where these industrial processes take place. For example, in electrowinning, an electrolysis process used to obtain several types of non-ferrous metals (e.g. copper and zinc, etc.), involves using caustic acids, e.g. sulfuric acid. In facilities where electrowinning is carried out, a significant amount of sulfuric acid mist is released to the ambient air.

Acid mist is an airborne mist formed by two phases: a gaseous phase and a liquid phase. The gaseous phase typically contains oxygen generated from the anodes surfaces in the electrolytic process, and atmospheric air (oxygen and nitrogen) typically diffused from the bottom of the electrowinning cell for gentle agitation of its electrolyte. The gaseous phase also contains vapors of water and sulfuric acid that are captured by the bubbles of air and oxygen that ascend within the electrolyte and release their contents into the air once they explode upon reaching the surface. In addition, other gases that may be present in the electrolyte, as impurities (such as Atacamite et al) originally contained in the mineralization of copper oxide ores, are likewise captured from the electrolyte by the ascending bubbles and are also released into the air, and form part of the acid mist during the industrial electrodeposition process.

The liquid phase of the acid mist is formed by fine airborne droplets of electrolyte and sulfuric acid suspended in the gaseous phase. These fine droplets result from the projection of electrolyte particles by the collapse of the liquid interfacial film surrounding the surface of the bubbles when they reach the electrolyte surface and explode. The gaseous bubbles ascend through the electrolyte to its surface, —they not only grow (and thus increase their buoyancy and velocity)—but also capture vapors of water and sulfuric acid in their interior (and any other vapors or gases present in the electrolyte). Just below the electrolyte surface the differential pressure in the interior of the bubbles and ambient atmosphere makes them explode. In bursting, the bubbles drag along very small liquid fragments of the interfacial film enveloping the non-ferrous metal sulfate solution in the electrolyte, and release their contents of vapors of water and sulfuric acid, all forming a complex pollutant gaseous phase known as called “acid mist”; which unless contained by physical barriers, emanates freely from the open cell containers and floods the working atmosphere of industrial electrodeposition tankhouses, polluting the ambient air.

In the tankhouse working atmosphere, acid mist polluted air constitutes a severe occupational health hazard, and accordingly, mist concentration limits in the atmosphere is established in corresponding Health and Work Safety Protocols and Regulations. In copper electrowinning facilities, for example, presence of acid mist in ambient air is known to cause multiple operational encumbrances, such as corrosion of installations, equipment and structural concrete structures, etc.; and other hazards and process inefficiencies associated with electric usage, such as electric current leaks by the crystallites and buildup of CuSO₄, copper node formations on the cathode plates and electrode short circuits, with attendant production losses and hazards.

Several prior art systems are known for the industrial capture and confinement of acid mist from electrolytic cells, in chambers formed by at least two cell walls, a bottom or floor and a ceiling or roof; such as hollow hoods and flat covers placed on top of the cells, impermeable covers installed on the electrodes above the electrolyte, supplemented with flat covers for vertical closure at both ends of the cells installed above the electrolyte at the same level as the impermeable covers; the bottom or floor in all system is the surface of the electrolyte; and the side walls contentions are the respective lateral walls of the cells and the vertical flat surfaces of the electrodes. Several examples can be found in the state of art in WO 2009/025837 documents; WO 2012/061949; GB2076856; U.S. Pat. No. 4,668,353 and U.S. Pat. No. 5,470,445.

Whichever cover system for the capture and confinement of acid mist is used in the cells, the volume of gases, vapors and gaseous fluids generated by the electrolytic process inevitably lead to a rise in the pressure inside the volume for confinement above the electrolyte; and eventually, when the confinement volume pressure rises above the ambient pressure of the tankhouse, the higher pressure will inevitably initiate a leak flow of acid mist from each of the cells to the tank house working atmosphere.

However, prior art systems using nonporous rigid covers, such as hoods placed on top of the cells, present a number of well-established short comings and inconveniences. Acid mist control systems used in industrial electrolytic tankhouses, capture the acid mist generated by each cell by confining it with hoods or other nonporous covers, and have means for extraction the acid mist from the confinement volume in each cell of a plurality of cells working side by side; gaseous fluid from each cell is collected by manifold pipes connecting to a network of large diameter ducts leading to a centralized depurator installation for acid mist treatment, sized to handle the rate of global acid mist volume extracted from the plurality of cells in the tankhouse. But the generated acid mist volume from each cell of a plurality of operating cells has to be moved by taking in air from the tankhouse ambient in sufficient volumes and with sufficient suction and velocity, so that resulting gaseous fluid volume from each cell can stay airborne while entrained through the ducting from the most remotely located cell to the designated location of the centralized depurator installation. Likewise, the external air suction device source needed to extract and move the acid mist, must be sufficiently large to handle not only the modest volumes of acid mist generated in each cell by its operating current density, but more importantly, also whatever additional volume of external carrier air is required and necessary to transport, at sufficient horizontal speeds, the now considerably increased global mass of diluted acid mist; (so that droplets of electrolyte entrained in the global gaseous fluid remain airborne and do not crystallize in the travel from each cell), all the way through the network maze of piping and ducting connecting the cells with the remote acid mist depurator treatment installation.

Worldwide experience shows also secondary problems or consequences exist, directly derived from the concept of moving high volumes of carrier air for entraining acid mist with very modest amounts of fine drops of electrolyte in suspension through the maze of ducts for considerable distances, such as the following:

(1) Inevitable crystallization of the very fine CuSO₄ airborne droplets in curve dead spots inside the maze of ducts, which need systematic cleaning at all times to prevent obstruction and crystallization buildups, that not only decrease the effectiveness of the centralized depurator treatment installation, but provide paths for high amperage current leaks that decrease overall electrodeposition current efficiencies;

(2) Aggressive high corrosion caused by acid mist of all equipment and Tankhouse installations;

(3) Maintenance of the expensive and fragile acid mist confining and/or extraction devices, such as the acid mist hoods current art in industry.

Prior art systems for capturing acid mist suffer from thermal losses caused by the large volume of air infiltrated from the tankhouse into each cell, which is generally at a lower temperature than that of the process electrolyte; the large volumes of colder air intake into the cells further imparts not only uncontrolled thermal losses in the circulating electrolyte, but more importantly, also enhances electrolyte evaporation; in fact, creating substantially more acid mist and exacerbating pollution much more than the electrolytic process itself generates!. The electrolyte thermal losses have to be made up by increasing the external heating required to restore the working temperature required in each particular electrodeposition process.

Moreover, prior art hood type systems suffer from yet another serious operational and environmental shortcoming: hood covers require removal from each cell in order to access the cathodes for harvest; with consequences: (1) wasted crane time and (2) no available floor space to retrieve/store hoods in most existing installations (built without considering acid mist hazards); and/or more recently, (3) complex automatic cranes that retrieve hoods while lifting the cathodes, and replacing the hoods before moving the cathodes, to minimize the time the cell electrolyte is exposed in direct contact with the working atmosphere. In effect, upon uncovering energized cells in operation, the accumulated confined volume of acid mist under the hoods is discharged directly to the work environment; and any time the electrolyte continues exposed, it inexorably emits uncontrolled acid vapors and aerosols of fine droplets of electrolyte to the global environment of the tankhouse. So while cells are being harvested, the maximum allowed concentration of hazardous substances in the work ambient in the vicinity of cells far exceeds the limits of applicable Health and Work Safety Protocols and Regulations, an unacceptable shortcoming to the health and occupational hygiene of workers plus decreased plant productivity.

More importantly prior art systems for controlling acid mist cannot assure sustained and full compliance of the mandatory maximum content limits of contaminants continuously at all times in all the working areas in the tankhouse. Therefore, there is a need for a method and system for virtually eliminating pollution by hazardous chemicals, such as acid mist, from the air resulting from an industrial process, such as electrowinning and refining of non-ferrous metals.

SUMMARY OF THE INVENTION

The invention provides a method and an integrated system for continuously eliminating acid mist generated in electrolytic cells, as it is being generated in the case of electrodeposition processes of non-ferrous metals, such as copper and zinc. Cathodic electrowinning processes using sulfuric electrolytes, massively utilize insoluble lead anodes. The gaseous fluid generated by the electrowinning cell operation contains a mixture of oxygen bubbles generated at the surfaces of the anodes caused by the flow of high amperage direct current that powers the cell, and from the diffusion of air bubbles from the bottom of the cells to gently agitate the electrolyte.

To avoid the contamination of ambient air with acid mist, a system embodying the invention provides a continuous controlled extraction of the acid mist as it is generated from each cell in operation. To assure the gaseous flow direction stays always from the tankhouse atmosphere into each cell and not in reverse, the extraction flow rate is regulated in such a way so that a stable, slight depression is continuously sustained in the hollow volume coalescer mini chambers (30a) formed by the double longitudinal horizontal seals, and likewise in all confinement mini chambers (30b) and in all the confinement volumes (30) of each cell. The latter concept is applied in each and all cells of a system of connected cells operating side by side in the tankhouse.

A first goal of precluding acid mist in electrowinning tankhouses is achieved, according to the invention, by a guaranteed condition of sustained null emission of acid mist from each cell individually of a plurality of cells to their work environments in the tankhouse, established permanently with continuous instantaneous monitoring of process variables in real time, to specifically eliminate the health hazards and thus—eliminate the need for compulsory use of respiratory devices in the working areas of electrowinning tankhouses.

A second goal of eliminating acid mist in electrowinning tankhouses is achieved, according to the invention, with a substantial decrease of electric energy requirements for the capture, confinement, extraction, transport and treatment of the acid mist generated in each cell. The latter goal is achieved by implementing a “cell by cell” strategy instead of the “centralized” acid mist treatment strategy” common in all of the present art systems up to the present day.

Other goals of the invention are achieved by a substantial decrease of thermal energy losses, compared to prior art, by decreasing to an absolute minimum the air intake volume of colder working ambient air from the tankhouse into each cell, needed to replace the volume of acid mist and air being continuously extracted from the confinement volume; the small mass of colder air intake avoids cooling the electrolyte, and in fact, simultaneously takes advantages of atmospheric pressure to assist in minimizing the suction energy required for the extraction of the confined acid mist in each cell, while also eliminating all electrolyte exposure to direct contact, at all times, with the work ambient while the cell is in operation.

A “cell-by-cell” implementation, according to the invention, compared to prior art: (a) eliminates the ducting maze, (b) any travel distance of substantially increased volume diluted acid mist (c) and the need for a remote centralized acid mist depurator treatment installation altogether. In fact, “cell-by-cell” implementation immediately recycles all the useful components of the acid mist generated by each cell, both “in situ” right inside each cell where they originate, and also immediately upon the extraction of acid mist from each cell. In particular, the invention utilizes a functional removable anodic cover that is designed to promote coalescence of the liquid electrolyte particles dispersed as fine airborne drops in the acid mist. The latter cover actually enhances coalescence and growth of fine droplets of liquid until they fall back by gravity into the electrolyte without leaving the container. The remainder de acidified confined acid mist generated in each cell is individually extracted from each cell and carried to at least one or more successive depurators devices for further substantial cleaning of the gaseous fluid and returning immediately the resulting condensate back to the cells.

“Cell-by-cell” strategy provides immediate double or multi treatment of the gaseous fluid from each cell, with at least a primary acid mist depurator device installed on one external front wall in each cell; from the acid depurator device, the acid condensate is recovered and recycled immediately back to the process, while the partially or totally de-acidified gaseous fluid goes through a secondary multistage acid mist condenser/depurator device provided for similar primary acid mist depurator treatment of several gaseous flows from adjacent cells. Said second multistage condenser/depurator device is equipped with means for positively enhanced effectiveness in reducing the H₂SO₄ vapors to innocuous levels in the treated gaseous fluid finally discharged to the open atmosphere.

“Cell-by-cell” preferred execution in this invention not only eliminates all causes for the secondary operational problems and harvesting shortcomings of the prior art, and facilitates harvesting and other tankhouse tasks effectively and in an operator, friendly manner.

To simultaneously achieve the sustainability goals stably in time, it is essential to provide a reliable programmable automatic controller system including a continuous instantaneous monitoring of process variables in real time, for their precise measurement and instantaneous control and self-regulation of the extraction flow of acid mist at each individual cell, and simultaneously, at the global acid mist flow level of the plurality of cells in the tankhouse. The programmable monitoring and automatic controller system of the invention is comprised of two (2) separate control systems that operate concatenated. At each cell, a first control subsystem is provided for individual monitoring in real-time, measurement and instantaneous self-regulation control of its actual acid mist extraction flow rate setting. A second control subsystem for global monitoring in real time, measurement, control and instantaneous regulation for the minimum suction requirement for the total extraction of acid mist demanded instantaneously by the sum of each suction demand by each cell of the plurality of cells.

To further facilitate the understanding of the present invention, the descriptions are based on “real” measured results, obtained from the continuous operation of a prototype of the equipment included in a system for acid mist recovery/recycling, as applied in four (4) pilot cells in an industrial cathodic copper electrodeposition plant operating alongside with 96 identical cells.

Sustained, prolonged continuous operation of the 4-cell copper electrowinning Prototype were run—first—manually controlled in pilot tests in an industrial plant, which evidenced that if the number of cells connected to the system for capturing and eliminating acid mist by recovery/recycling is scaled up to include a plurality of cells larger than four, the requirements of precision of controls and reaction speed of manual adjustments necessary to keep in balance the continuous operation of the system, maintaining stable close control of extraction flow rate both at the individual cell level and concatenated with the global extraction level in the Extraction System must necessarily be automatic, since manual controlled operation (even by trained qualified operators) becomes both impossible to continuously sustain assured effective control and regulation in real the condition of “100% Null Escape of acid mist” “cell by cell”, and also ineffective to simultaneously achieve instantaneous stable concatenation of the global suction in the Extraction System, to achieve desired invention goals results simultaneously, steadily and reliably sustained over time. Furthermore, appropriate sensors in PAC's can provide the levels of redundancy necessary for 100% continuity of compliance with the performance assurance levels expected of devices controlling quality of air in human health working environments.

BRIEF DESCRIPTION OF THE DRAWINGS

In following, FIGS. 1.1, 1.2, 1.3 and 1.4 will be collectively referred as FIG. set 1; FIGS. 3.1, 3.2, 3.3, 3.4, 3.5 and 3.6 will be collectively referred as FIG. set 3; FIGS. 4.1 and 4.2 will be referred as FIG. set 4; FIGS. 5.1 and 5.2 will be referred as FIG. set 5; FIGS. 6.1, 6.2 and 6.3 will be referred as FIG. set 6.

FIG. 1.1 represents an assembled electrowinning electrolytic cell in accordance with an embodiment of the invention.

FIG. 1.2 shows an exploded view from above the electrolyte level (13) in the cell, with anodes projecting upwards from the electrolyte, the double longitudinal seals (6) of the RAC system (5) resting on the cathode plates form hollow coalescer mini chambers (30a) above regular mini chambers (30b) for confinement of the acid mist in the inter electrode spaces formed above the electrolyte as confinement volume; both mini chambers discharge transversely on both ends into the collector lateral channels (20), next to the cell (1) lateral walls, to direct and maintain the gaseous fluid flow towards the discharge end of each cell.

FIG. 1.3 shows an exploded view of the total volume available for acid mist confinement in the cell (1), determined by the electrolyte level (13) and the level (12) immediately below RAC system (5). (The minimum practical height between these two levels determines also a minimum electrolyte evaporation condition).

FIG. 1.4 shows perspective view of RAC system (5) (cathodes and anodes removed) complete with its flat covers (14 and 15) on both ends of each cell (1).

FIG. 2 is a cross section elevation of an individual cell representing the components for the electrodeposition process of non-ferrous metals, with individual RAC installed.

FIG. 3.1 represents an elevation view in longitudinal cross section of cell (1), showing disposition of complete RAC system.

FIG. 3.2 shows an elevation view in longitudinal cross section of cell (1), showing the cathode plates (4) with electrodeposits coated on both flat surfaces.

FIG. 3.3 shows elevation view in longitudinal cross section of cell (1), (with lateral cell wall removed), showing electrolyte (2) at its level (13), forming the bottom of each lateral channel (20) that collects the acid mist confined in the transversal mini chambers forming the transversal hollow coalescer mini chambers (30a) and also regular mini chambers (30b) (bellow the hollow coalescer mini chamber (30a), spaces between anodes (3) and cathodes (4) which have been removed) and move the gaseous fluids to the acid mist extraction rig (15a) for discharge into the acid mist bubbling device installed in each depurator (16).

FIG. 3.4 is an enlarged longitudinal cross section view of the mounting of the individual RAC's (5) to show the inner seals (6d) that apply pressure on the anode plate, keeping the RAC permanently attached to the hanger bar; and inner seal (6c) that acts as a stiffener of the upper flexible longitudinal seal to assist pressure contact with the cathode plate.

FIG. 3.5 shows a longitudinal cross section view in elevation of cell (1) (as above), with the extended positions of the double longitudinal seals (6), when the cathodes plates (4) are removed, with plated electrodeposits (4a) to harvest the non-ferrous metal, the volumes of hollow coalescer mini chambers (30a) immediately expand horizontally so that the longitudinal laminar seals of adjacent anodes overlap with each other, closing the interelectrode gaps permanently; in effect, while the cells are in operation, their electrolytes remain always closed from contact with the working ambient air.

FIG. 3.6 is an enlarged detail of FIG. 3.5; and shows two adjacent covers of the RAC system (5) with the cathode plate removed. As can be seen, the laminae of the double longitudinal lateral seals extend outward horizontally and overlap tightly in their extended positions forming two hollow volume coalescer mini chambers (30a).

The super imposed dotted line represents a temperature gradient in the vertical cross section e.g. temperatures 28°-30° C. in the tankhouse ambient air outside the individual (5) RAC's shown and at an estimated average temperature of approximately 35° C. inside the expanded hollow volume of the coalescer mini chamber formed by the adjacent double longitudinal seals. The operation of the invention requires controlled intake of tankhouse air into the cell confinement volume (30) at approximately 2 millibars depression with respect to tankhouse ambient pressure in order to move the acid mist in the confinement volumes towards the gaseous fluid extraction end of the cell. The curly arrow (6i) represents a small volume of air intake at 28°-30° C. (aided by atmospheric pressure in the working ambient and the slight depression maintained under the RAC's (5) in each cell), entering continuously, through the overlapped double longitudinal seals with temperature in its interior, filled with acid mist, at approximately 33°-35° C., producing a chilling effect in the acid mist for enhancing the conditions for continuous coalescence of small droplets of electrolyte (2). In turn, the bottom of the hollow mini chambers are at 36°-37° C., slightly below the temperature in the confinement volume of the interelectrode space underneath, of about 37°-40° C., considering the cell electrolyte (2) is at 43° C.

In effect, the hollow coalescer mini chambers in each interelectrode space in the cell act as transverse chillers of the confinement volume below them, thus promoting acid mist coalescence throughout the entire volume of the confined acid mist. The hollow coalescer mini chambers are unique feature of the RAC system (5).

FIG. 4.1 shows the removable anodic cover system (RAC) in perspective.

FIG. 4.2 shows an exploded view of one the removable anode covers of the RAC system (5).

FIG. 5.1 shows a schematic installation of system for capturing acid mist and eliminating acid mist from the working atmosphere, and optionally recycling the acid condensate, with manual control, installed on four (4) industrial electrowinning cells operating with a cover system for confinement of acid mist (as disclosed above).

FIG. 5.2 represents a primary or first depurator device for removing electrolyte and acid droplets and sulfuric acid vapors from the captured and extracted gaseous fluid.

FIG. 6.1 shows the exterior view of the second multi chamber depurator condenser of 4 vertically stacked, connected chambers (4 stages), (device (60)), to immediately continue deacidification of the individual cell's gaseous flows from a plurality of cells.

FIG. 6.2 shows the interior of four (4) chambers stacked vertically (61), (62), (63) (64) constituting device (60) to provide successive immediate multiple stages for removing acid vapors, from the gaseous fluid flow.

FIG. 6.3 shows the turbulent bubbler installed in first chamber (61) of device (60).

FIG. 7 is a block diagram representing components of a process variables monitoring system in real time providing information for the programmable automation controller, in accordance with an embodiment of the invention.

FIG. 8 is a flowchart diagram representing method steps in the process of eliminating acid mist from one or more electrowinning cells, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

The invention relates to a method and a system for precluding contaminants/pollutants from polluting the air in working ambient that is typically contaminated as a result of carrying out certain industrial processes. Several concepts are combined in a novel manner leading to elimination of contaminants from the air. The invention as disclosed was implemented in a copper electrowinning facility to remove sulfuric pollutants that typically contaminate the air in working areas within the industrial facilities. Implementations of the invention as disclosed can be adapted to rid air of contaminants in a variety of industries using the teaching of the invention and without burden. Therefore, in the following description, numerous specific details are set forth to provide a more thorough description of the invention. It will be apparent, however, to one skilled in the pertinent art, that the invention may be practiced without these specific details. In other instances, well known features have not been described in detail so as not to obscure the invention.

Part of the concepts described below have described in PCT application number PCT/CL2014/000026, U.S. application Ser. No. 14/899,305, and U.S. Pat. No. 9,498,745 (to be issued), each of which is included herein by reference.

Terminology

Throughout the disclosure, a reference to “air” should be considered in the context of the sentence in which the term “air” is used. For example, when referring to the term “air” in reference to the air emanating from the electrowinning process, “air” then refers to the air from bubbles of soft aeration system for gentle agitation of the electrolyte injected in that cell mixed with any gas and/or vapor resulting from the industrial process. Likewise, from bubbles from a soft aeration system within an industrial facility, the term “air” may refer to the hazardous polluted air in the facilities, such as found in prior art facilities, or as breathable contaminants-free air released by an embodiment of the invention.

Contaminant is any hazardous substance in any phase (e.g., gas, liquid or solid) the concentration of which is considered unhealthy or unacceptable above a maximum regulated level.

Throughout the disclosure, hollow volume coalescer mini chambers, regular cell mini chambers, containment or confinement chamber, containment or confinement volume refer to the volume in each electrowinning cell under a cover installed on the cell/tank/container where the process is conducted, which allows for capturing the gases (including air) emanating from an industrial process (e.g., electrowinning).

A reference to a vapor (or vapors) invokes any component substance of a gaseous phase that is condensed by exposure to simple chilling to temperatures slightly inferior to that of its environment at atmospheric pressure.

A permanent gas in the disclosure is any component substance having a gaseous phase that requires temperatures significantly below 0 degree Celsius and pressures substantially above atmospheric pressure to condense or liquefy.

Implementations of the invention have been shown capable to reduce the concentration of contaminants to undetectable levels (see below). However, while in the context of specific implementations of the invention, as disclosed, the concentration of contaminants may reach a zero (0), “elimination” is considered as achieved once the concentration of a contaminant has reached a level considered as practical, such as reaching a level that complies with or exceeds applicable current health standards.

Throughout the disclosure, sustained (or continuous) treatment refers to the outcome of the treatment and removal of contaminants from the contaminated air i.e, without disrupting the industrial process. In the metal electrodeposition processes, described below, maintaining a constant pressure within the cells is found advantageous; however, it is conceivable that in other implementations of the invention, treatment may be temporarily disrupted.

Unless otherwise specifically defined, terms, phrases and abbreviations used in this disclosure are commonly known in the art of obtaining metals by electrowinning processes.

Overview of the “Cell by Cell” Concept

The main goal of the invention is to eliminate a contaminant in the air emanating from an industrial process to undetectable levels in said air or at least reduce the concentration of the contaminant to levels that are non-hazardous and considered acceptable by health standards. The latter goal is achieved in embodiments of the invention using an integrated system that comprises a capture/confinement apparatus of the contaminated air, a decontamination apparatus that on one hand recovers the contaminants and on the other hand rids the captured air of its contaminants, and it is then released to the open atmosphere. Furthermore, in the case of air contaminants that are considered as part of the industrial process, the pollutant substance is recycled and returned into the process, thus reducing the cost of production. Each of the apparatuses may be implemented at any single unit of production of the industrial process, this allowing for a scaling up/down of the system. The system also comprises a computer automatic control system that includes monitors in real time for the variables of apparatuses at each unit of production, and as a concatenated process of all production units. In a system embodying the invention for treating contaminated air in an electrowinning industrial process, the capture/confinement apparatuses comprise a sealed lid that covers each cell and provides a confinement/collection chambers where acid mist can be extracted out of the chambers under controlled suction. The collected condensed fluid is carried through manifolds toward one or more tanks for dissolution. The acid and electrolyte drops contained in the gaseous fluid are thus diluted into a liquid (or water). After one or a few stages of air dilution into a liquid (or water), the acid is eliminated from the gaseous fluid, and can safely be released into the open atmospheric air, all the above utilizing one global suction source in the Extraction System.

Another system embodying the invention for treating contaminated air in an electrowinning industrial process, is similar to the preferred embodiment above, but differing in that the extraction of acid mist form the cell can be done “cell by cell”, utilizing individual acid mist extraction devices, that discharge the gaseous fluid flows into the first depurators attached to each cell, and further into manifolds of the secondary gaseous flow treatment.

System for Removing Acid from Air in Electrowinning Cells

An embodiment of the invention is adapted to eliminate acid mist generated in electrolytic cells used for electrodeposition of non-ferrous metals, such as copper and zinc among others, based on the results of coordinately concatenating three interdependent systems (FIG. sets 1, 4, 5 and 7) implemented in series together in each cell of a plurality of cells operating side by side in an electrowinning tankhouse.

A collection apparatus comprises a removable anodic cover (RAC) system (FIG. sets 1 and 4) for capturing, confining and substantially recycling the acid mist components generated in each cell by its operating process conditions, that effectively isolates at all times the electrolyte and the acid mist from the working atmosphere in the interior of the tankhouse; and connected to the suction of the second system for the continuous extraction and abatement in situ of the acid mist.

A second system for individual continuous extraction of confined acid mist from each cell, and immediate treatment of the gaseous fluid actually extracted to substantially abate the contaminants entrained in the gaseous fluid flow, which are recycled back to the electrowinning process as condensate with substantial recuperation of water, sulfuric acid and copper, and simultaneously, maintaining stable the normal functional characteristics of the continuous/batch electrowinning process in each cell, and likewise in the plurality of cells in operation in the tankhouse.

The system implements an automation apparatus: a programmable automation controller (PAC) system that includes seamless instantaneous monitoring of process variables in real time and providing automatic concatenated control of both control subsystems for consistent and stable achievement of the invention goals. The PAC's designed with one or more components/control subsystems such as a first subsystem I (“I”, shown in FIG. set 7), for monitoring in real time the extraction flow rate of acid mist from each cell and maintaining individual given setting of extraction flow rates auto regulated instantaneously required for each cell. A second control subsystem II (“II”, shown in FIG. 7) is used, for instantaneous, real time, auto regulated control of the global suction flow rate supply the global demand of suction by the sum of gaseous fluid rates set at each cell of the plurality of cells operating side by side in the tankhouse. The latter configuration, i.e. instantaneous and simultaneous auto regulation, results in assured minimum usage of electric power.

The integrated system of the invention has been implemented and validated by 7,000 hours of nonstop testing demonstrating its efficacy to eliminate acid mist from the electrowinning facility, and simultaneously its efficiency to reduce power consumption to <100 Watts/cell, and including enhance results of the electrowinning process by the application of soft aeriation of the electrolyte. Results disclosed in this application have been duly certified by an independent expert third party. The results with both manual and automatic PAC “cell by cell” control are totally coherent, but automation makes the “cell by cell” strategy practical and effective for massive, immediate “noninvasive” application—duly “tailored”—to the characteristics of each operating copper electrowinning plant, irrespective of size, type of cells, cell technology, electrodeposition process, date of construction, or world location.

FIG. set 1 (including FIGS. 1.1, 1.2, 1.3 and 1.4) represents an electrowinning cell having a removable anodic cover (RAC) system in accordance with an embodiment of the invention. A first precursor embodiment of the cover system for electrowinning cells in this invention is disclosed in US patent application publication number US 2016/0158686 A1, published on Jun. 9, 2016, by the same Applicant as the current application. The latter publication content is included herein by reference in its entirety.

In brief, the removable anodic cover system comprises a cover mounted by insertion on the horizontal straight portion of the hanger bar of each anode in the electrowinning cell, and completed with flat covers installed on both ends of each cell, including the connection with the devices of the system for capturing acid mist and eliminating acid mist from the air, and optionally recycling the acid. The anodic cover system represented in FIG. set 1 is designed for easy installation and removal from the supporting anodes in individual cells. Individual anodic cover devices can also be supplied joined together in partial anode sections or in full length of the anodes in the cell (not shown).

FIG. 1.1 represents an assembled electrowinning electrolytic cell in accordance with an embodiment of the invention. The electrowinning electrolytic cell (1) of FIG. 1,1 comprises a RAC system (5) installed on anodes (3)—and connections to cell extraction rig (15a) and external ducts (15b). The external ducts (15b) carry the gaseous flow up and over the cell end wall. The ducts and walls are duly sealed to avoid any escaping of acid mist, and carry the captured acid mist to a first depurator device (16) of acid vapors and airborne electrolyte droplets, which is part of the system for capturing acid mist and eliminating acid mist from the air, and optionally recycling the acid vapors. The first depurator (16) may be preferably mounted on the same end wall of each cell (1) through single inlet pipe (18).

FIG. 1.1 represents the gaseous fluid discharged from the first depurator device (16) through pipe (18a) collected by manifold (54) to immediate further secondary treatment of acid mist from each cell, and simultaneously, the liquid acid condensate being discharged from first depurator device (16) through pipe (18b) for collection with manifold (52) and immediately collected in reservoir (53) for recycling back to the process.

FIG. 1.2 shows an exploded view from above the electrolyte level (13) in the cell, with anodes projecting upwards from the electrolyte, forming mini chambers for confinement of the acid mist in the inter electrode spaces, discharging transversely on both sides into the collector lateral channels (20), next to the cell (1) lateral walls, to direct the gaseous fluid flow towards the cells discharge end.

FIG. 1.3 shows an exploded view of the key total confinement volume available for acid mist in the cell (1), determined by the electrolyte level (13) and the level (12) immediately below RAC system (5). (The minimum practical height between these two levels determines also minimum electrolyte evaporation). The total confined volume in each cell is directly connected to its first depurator device (16), by gaseous fluid discharge pipe (18a) and liquid condensate discharge pipe (18b). The acid mist generated by each cell in operation must be extracted continuously so as to create a slight depression (with respect to atmospheric pressure) by closely controlled gaseous fluid extraction rate from the minimum confinement volume possible, so that a controlled minimum volume of tankhouse air is forced into the cell by the depression under the RAC system (5), and thus making it impossible for the acid mist to escape from each cell to the working atmosphere.

FIG. 1.4 shows perspective view of RAC system (5) (with cathodes and anodes removed) complete with its flat covers (14 and 15) on both ends of each cell (1).

FIG. 2 is a cross section elevation of an individual cell representing the components for the electrodeposition process of non-ferrous metals, with an individual RAC installed. The cell in FIG. 2 shows a confinement and transportation volumes bellow the RAC system available for confinement of the generated acid mist by each cell. FIG. 2 shows the elevation of transversal cross section of cell (1) containing volume of electrolyte (2), with immersed anode plate (3), with its anode hanger bar (11b), immersed cathode plate (4) with its cathode hanger bar (11a), with RAC system (5) installed in operating position with double longitudinal seals (6) designed for controlled permeability for air intake, showing an electrolyte soft aeration system with its isobaric diffuser ring (7) installed in working position, near the bottom of cell (1) and parallel to the ends of electrodes (3), (4); the monolithic guide horns (8) protruding upwards on both ends of RAC system (5) for guiding returning empty cathode plates into designated working position in the cell after harvesting. The electric current bar (9) installed on electrode capping board spacer/insulator (10); view shows highlight of the upper level of the acid mist confinement space in each cell (12) in transverse hollow coalescer mini chambers (30a) regular mini chambers bellow (30b) and the electrolyte level (13) which marks the lower boundary of acid mist confinement space of mini chambers (30b), with their discharge into lateral channels (20) that run parallel to the lateral cell walls (1).

FIG. set 3 (including FIGS. 3.1, 3.2, 3.3, 3.4, 3.5 and 3.6), represent longitudinal elevation cross sections of an individual cell at different longitudinal vertical planes, showing the devices of the system for capturing and confining acid mist, in accordance with an embodiment of the invention.

FIG. 3.1 represents an elevation view in longitudinal cross section of cell (1), showing disposition of complete RAC system (5) mounted on hanger bars (11b) of each lead anode plate (3); with its flat end covers (14) and (15) for sealing the electrolyte tank from the atmosphere surrounding cell (1); cathode stainless steel plates (4) are shown with layers of electro-deposited nonferrous metal (4a) coated on both flat surfaces; the acid mist cell extraction rig (15a) that removes the gaseous fluid from each cell (1), and discharges the gaseous fluid directly into the first depurator of acid mist (16) mounted on the exterior of a frontal wall of each cell.

FIG. 3.2 shows an elevation view in longitudinal cross section of cell (1), showing the cathode plates (4) with electrodeposits coated on both flat surfaces (4a) hoisted by a crane (not shown) to harvest the metal electrodeposits (4a); also shown are RAC system (5), anode plates (3), flat end covers (14), (15), acid mist extraction ducts (15b), (16), bubbler device (17) with discharges of gaseous fluid (18a) and acid condensate (18b).

FIG. 3.3 shows elevation view in longitudinal cross section of cell (1), (with lateral cell wall removed), showing electrolyte (2) at its level (13), forming the bottom of each lateral channel (20) that collects the acid mist confined in the transversal mini chambers (30) (spaces between anodes (3) and cathodes (4) which have been removed) and move the gaseous fluids to the acid mist extraction rig (15a) for discharge into each depurator device (16).

FIG. 3.4 shows elevation view in longitudinal cross section of cell (1), showing details with double longitudinal seals (6) of RAC (5) with flexible laminae on each side of RAC (5) resting on the flat surfaces of the adjacent cathode plates (4), thus substantially sealing the electrolyte between its level (13) and the lower face of the double longitudinal seals (6) of RAC system (5).

FIG. 3.5 shows a longitudinal cross section view in elevation of cell (1) (as above), with the extended positions of the double longitudinal seals (6), when the cathodes plates (4) are removed, with electrodeposits (4a) to harvest the non-ferrous metal, the volumes of mini chambers (30a) are expanded. The “controlled infiltration of atmospheric air” is shown with curly arrows (6i), which is determined by the permeability of the horizontal overlap of the double longitudinal seals (6).

Each bottom horizontal flexible laminae of the double longitudinal seals (6) is separated from the upper parallel flexible laminae by a given dimension to form a hollow “coalescer transversal mini chamber” (30b) in each interelectrode space of the cell when double longitudinal seals are attached on each RAC (5). The height of each hollow mini chamber is determined by the height of the acid mist confinement volume over the electrolyte of the cell, which in turn, influences the electrolyte's rate of evaporation in the window of electrolyte temperatures (in which the cell normally operates) and ambient temperatures in which the electrodeposition process is conducted. The height of the hollow mini chambers is best seen in FIG. 3,5, showing the hollow mini chambers when the cathodes removed from the cell.

FIG. 3.6 is a close-up detail vertical cross section of two adjacent hollow coalescer mini chambers (30a) shown sharing a common internal volume caused by the removal of the intercalated cathode (4); a common roof and bottom are formed by the corresponding overlaps of the adjacent double longitudinal flexible seals (6). FIG. 3.6 shows the temperature gradient between typical tankhouses ambient and electrolyte temperatures applied on the enlarged detail of two adjacent anodes with CAR installed, and the estimated intermediate temperatures of the flexible laminae of the double longitudinal seals (6) that form the hollow coalescer mini chamber (30a), in which the roof is cooler than the bottom. The temperature of the acid mist generated at the electrolyte level (12) is very similar to the actual electrolyte temperature, but as the mist gets airborne and closer to the interface of the confinement volume (13), the cooler bottom of the hollow mini chamber (30a), (at 3° or 4° lower temperature than the mist), as mist ascends in the colder temperature zone, the coalescence process augments, and the very fine drops of liquid fragments of electrolyte airborne in the acid mist begin to merge or coalesce into larger size drops, as their combined masses grow. As the acid mist continues its ascent and penetrates inside the hollow “coalescer” mini chambers; a similar process occurs, only slightly faster by the yet diminished temperature inside the volume of the hollow coalescer mini chamber. Typically, coalesced drops of various sizes can be seen attached and hanging to the flat underside of the transparent flexible laminae seals of RAC (5), until their weight detach them and making them fall into the electrolyte, in effect, auto recycling themselves back into the cell electrolyte that originated them, without ever leaving the cell.

The vertical movement of both continuous double longitudinal seals (6) upon extraction of cathode plates (4) detaches the coalesced electrolyte drops from the surfaces of the double longitudinal seals (6) (not shown because they have already been recycled by gravity back to the electrolyte (2)). The periodic rearrangement of the volume of coalescence inside each mini chamber (30a) and (30b), with each harvest period provides a natural wiping mechanism for coalesced drops by the frictional action of the contact of the double longitudinal seals (6) rubbing against the cathode plate surface, once when cathode (4) are pulled out of the cell (1) for harvesting cathode nonferrous metal deposit (4a), and a second time, when the empty cathode plate (4) is returned to its working position in the cell.

FIGS. set 4 (including FIGS. 4.1 and 4.2), represents a perspective view of the removable anodic cover in accordance with an embodiment of the invention. FIG. 4.1 shows a perspective of the removable anodic cover RAC (5) for each anode of the cell, its structural monolithic, reinforced vinyl-ester composite body (5a) with longitudinal double seals (6) and frontal seals (6b) enveloping the oblique portion of each hanger bars (11b), and the flat horizontal overlapping flap seals (6a) that rest pressing on the lateral walls of the cell (1). FIG. 4.1 shows an exploded view of one removable anode cover of the RAC system (5) showing its double longitudinal seals (6) for controlled flow of air intake along the entire overlap of longitudinal contact resulting in very soft, uniform and smooth atmospheric cold air intake, specifically achieved to enhance coalescence of hotter fine drops of electrolyte suspended in the confined acid mist. The double longitudinal seals (6) extend over the entire length of the structural resisting body (5a), with a preferred monolithic molded embodiment in anticorrosive, high impact resisting, reinforced vinyl-ester composite, and with the frontal seals (6a) and (6b) tripling the sealing elements on both frontal extremes. This additional sealing above the lateral channels (20) is required for improved durability and control of the overall perimetrical permeability. The monolithic guiding horns (8) facilitate the reinsertion of empty cathode plates (4) vertically hanging suspended from the crane, upon returning the harvested cathode plates back to each cell (1), in their working position.

FIG. 4.2 shows an exploded view of one the removable anode cover of the RAC system (5) installed on the hanger bar (11b) of anode plate (3) and the resulting protrusion of the hanger bar (11b) arm through frontal flat seal (6b) and the horizontal single or double flap frontal flat seals (6a) provide single or double flap cover over the roofs of the lateral channels (20) resting against the cell lateral walls, providing tight and stable contact at all times; while flat seals (6b) improve guided air intake into the critical area above the roof zone of the laterals channels (20) and discharge zones of the mini chambers (30a) and (30b) into channels (20), all for extra assurance of localized compliance of “100% Null Escape” condition at this critical point, with the individually set extraction flow rates in the cells.

FIG. set 5 (including FIGS. 5.1 and 5.2) schematically represents the several components as connected within a system for removing acid mist from an electrowinning installation. The latter representation is shown and described in US patent application publication number 2016/0158686 A1 (published on Jun. 9, 2016), entitled: System for Recovering and Recycling Acid Mist Generated in Electrolytic Cells for Electrowinning or Electrorefining Non-Ferrous Metals.

FIG. 5.1 shows a schematic installation of system for capturing acid mist and eliminating acid mist from the air, and optionally recycling the acid system, with manual controls, installed on four (4) industrial electrowinning cells operating with coalesces mini chambers included in the cover system for confinement with simultaneous coalescence of acid mist (as disclosed above).

FIG. 5.2 represents a primary or first depurator device for removing very small electrolyte liquid particles airborne in the acid mist from the captured gaseous fluid. Device (16), which is referred hereinafter as depurator, effectively catches the remaining fine droplets of electrolyte in suspension from the extracted gaseous flow; the acid condensate captured in the depurator is discharged trough pipe (18a) and collected by manifold (52) for immediate recycling by flowing back to the electrodeposition tank. The gaseous fluid is then discharged through pipe (18b) immediately by manifold (54) to a secondary treatment device.

FIG. set 6, which includes FIGS. 6.1, 6.2 and 6.3, represents a secondary gaseous fluid treatment device for removing acid vapors from the captured gaseous fluid, in accordance with an embodiment of the invention. Device (60) represented in FIG. set 6 is shown and described in the US patent application publication number 2016/0158686 A1, published on Jun. 9, 2016, referenced above. Device (60), according to the invention, is built as a multi-chamber depurator/condenser device that removes acid vapors from the gaseous fluid captured from the electrowinning cells. For example, Sulfuric acid (H₂SO₄) vapor content in the gaseous fluid, once treated through device (60), reaches at least innocuous levels or is eliminated from the air. The depurated air may finally be safely discharged from the system into the open atmosphere.

FIGS. 6.1 and 6.2 show external and internal views, respectively, of a preferred embodiment of the secondary multi chamber depurator/condenser device (60).

FIG. 6.3 shows the turbulent bubbler (17a) (of larger capacity but otherwise similar to the bubbler (17) in each depurator (16)) installed in first chamber (61) of device (60), which consists of two parallel hollow headers (17b) connected to a plurality of parallel, perforated ducts (17c). The number and diameter of perforations are adjusted such as an aggressive turbulence is produced. Moreover, the height of the liquid column is set to maximize extraction of the acid mist from a plurality of cells.

FIG. 6.1 shows the exterior view of the second multi chamber depurator condenser of 4 vertically stacked, connected chambers (4 stages), (device (60)), to immediately continue deacidification of the individual gaseous flows received from each first depurator device (16) of a plurality of first depurators; the gaseous fluids enter device (60) from the bottom chamber through a second turbulent bubbler device (shown in FIG. 6.3), and ascends through a liquid column of controlled height, that assures capture of any remaining fine drops of electrolyte that could have been entrained by any of the various individual discharges from the first capture in the corresponding depurator (16).

FIG. 6.2 shows the interior of four (4) chambers stacked vertically (61), (62), (63) (64) constituting device (60) to provide successive immediate multiple stages for removing acid from captured vapors. The multi-chamber architecture of device (60) provides multiple stages of elimination of acid from the captured gaseous fluids. The turbulent bubbler shown in FIG. 6.3 is installed in the first chamber (61). Chambers in their interior are supplied with inclined, flat surface baffle plates (69) which increase the linear travel distance and friction contact in the upward passage of the global gaseous fluid flow. The acid condensate is discharged by overflow through tube (68), and the global treated acid mist coming from the plurality of cells, is discharged through duct (67) towards the suction turbine and out to open atmosphere.

Thus, fine drops of electrolyte that may be entrained in the gaseous flow beyond the first chamber (61), may be condensed in the adjacent chamber (e.g., chamber 62). The second chamber (62) is equipped with a plurality cooling tubes (66). The cooling tubes may be disposed transversely in bias for intercepting the flow of ascending acid gaseous fluid. The cooling tubes may be internally cooled by running a coolant, such as glycol cooling fluid, which is chilled by an outside chiller. The coolant's temperature is adjusted to provide low temperature (e.g., temperatures near 0° C.) within the plurality cooling tubes (66) in chamber (62) to promote condensation by lowering the temperature of the remaining fraction of sulfuric acid vapor. Condensate drops drop by gravity down to the liquid column in chamber (61).

In an embodiment of the invention, a third chamber (63) may be filled with a hygroscopic material, such as clinoptilolita zeolite granules, or any other equivalent substance for substantial absorption of any remaining gaseous vapor or acid humidity in the gaseous fluid flow.

In an embodiment of the invention, a fourth chamber (64) functions as an expansion enclosure, to maximize adhesion of any remaining entrained micrometric liquids on baffle surfaces disposed for that purpose.

Finally, the double treated acid gaseous flow enters the global suction turbine, with its original contents of acid pollutants in the acid mist extracted from each cell substantially reduced to innocuous levels, so as to maintain the turbine interior or any metal parts thereof free of corrosion.

FIG. 7 is a diagram representing components of a programmable automation controller, in accordance with an embodiment of the invention. The numbers in subscript following the numerical labels are references to the individual (per cell) implementation of a device that is referenced in multi-cell implementation. The subscript letter “n” is used hereinafter to reference any device of the system that is attached to individual cells. For example, sensor 19a1 references a sensor attached to a first cell, whereas 19a₂, 19a₃ and 19a₄ reference sensors attached to a second, a third and a fourth cell, respectively.

The programmable automation controller, represented in FIG. 7, concatenates instantly in real time the operation of the variables in the two independent control subsystems i.e. control subsystems I and II.

Control subsystem I acts at the level of each cell, providing instantaneous monitoring of variables in real time with individual “cell by cell” extraction flow control of acid mist at each cell. Control subsystem I allows setting a specific extraction flow rate of acid mist individually at each cell, independently of the settings in any other cell of a plurality of cells, thus sustaining its condition of “100% Null escape of the acid mist to the working ambient”.

Control subsystem H provides instantaneous monitoring and suction needed for the global (across-cells) acid mist extraction flow rate demanded by the summation of the extraction rate settings in each cell from the plurality of cells connected to the system.

As shown in FIG. 7, the system for instant monitoring of variables in real time is integrated into sub Control System I for monitoring and instantaneous automatic control of the individual extraction flow rate of acid mist from each cell (1), (each individual cell control is shown grouped inside blocks in dotted lines in FIG. 7, located adjacent to each depurator (16)); dotted line blocks actually represent the control boxes physically installed on the front wall of each cell (1); each control box lodges the individual extraction flow rate sensor (19a) that delivers instant analogous signals sensed to an electronic transducer (70n), which is transformed into a digital signal and is conducted to the FLUX CN1 Processor/Transducer (71) that commands the electric actuator of flow control valve (73n) and simultaneously transmits a wireless signal (74n) of the instant individual extraction flow sensed. At the same time, Processor/Transducer (71n) verifies the corresponding % aperture of its flow control valve and transmits it wirelessly in parallel with signal (75n), to the FLUX Coordinator Processor/Transducer (79), Sub Control System II.

Sub Control System II, likewise, provides instantaneous monitoring of the actual global flow rate and automatic controls the global aggregate instantaneous supply of required suction to sustain individual acid mist extraction rates from the plurality of cells; upon receiving wireless signals (74n) and (75n), transmits them through a FLUX Coordinator Processor/Transducer (79) which also receives the actual global instant gaseous fluid flow rate from analogous sensor (19b) which transmits it to transducer (78) and converts it into a digital signal for transmission to Processor/transducer (79). This global Processor/Transducer device transmits all the digital signals received to the remote monitoring platform for instant data recording and processing (deZem platform), and concurrently, compares the sum of individual signals of individual, extraction flow rates from each cell (19a) with the real global instant gaseous fluid flow rate sensed (19b) and instantaneously adjusts the difference—positive or negative—between the two signals, to a net signal which is sent to the frequency variator (82) to instantaneously adjust the global suction of the turbine to provide the aggregate demand of suction required in the sub Control System I.

Prototyping, Design and Operations

A prototype System for Elimination of Acid Mist was specially built and installed for continuous operation to recover and recycle the Acid Mist generated by four (4) copper electrowinning cells of 32 cathodes and 33 insoluble lead anodes in an industrial cathodic copper electrodeposition plant operating alongside with 96 other identical cells. All cells have sulfuric acid electrolyte with average composition: H2SO4 180 gram per liter at average temperature 43±1° C., operating with current density between 285 and 300 A/m2, at an altitude of approximately 700 meters above sea level.

The prototype was originally built (2012) and run continuously for 7 months according to the teachings schematically diagrammed in FIG. 5, to successfully validate the “cell by cell” concept for, Acid Mist elimination strategic. In 2015, necessary adaptations for running continuously with automatic controls, include a programmable automatic controller (PAC) as shown in FIG. 7 and described above.

Each of the 4 prototype electrowinning cells received its individual controls (FIG. 7) to provide instantaneous control and regulation of a specific extraction rate setting for individual cells. The intended goal was to maintain stable in time a condition of “100% Null Escape” at each individual cell stably in time. The latter setting of the extraction flow rate is independent of all other “100% Null Escape” setting in any one of the other cells in the system, and can be individually adjusted at any time if needed.

The 2015 prototype comprises in particular the following elements: an individual extraction flow rate sensor (19a); a signal transducer (70n); a software/hardware logic device (71n); an actuator device (72n); a flow control valve (73n) with proportional openings in each cell; an overall instantaneous extraction flow rate sensor (19b); a transducer (78) of the overall extraction flow rate; a global coordinator software/logic hardware device (74); a variable speed source of suction (82).

In the 2015 prototype for testing the performance of the invention, the individual rate flow sensor (19a) instantly delivers a sensed analogous signal to an electronic transducer (70n). Transducer (70n) converts the signal into a digital signal that is sent to a software/hardware logic device (71n) that compares the value of the individual cell instantaneous extraction flow rate sensed with the preset value (setting) to maintain the condition “100% Null Escape” of acid mist from each cell, and if adequate, sends an appropriate correction signal to actuator device (72n). The actuator 72, commands a flow control valve (73n) in each cell. Software/hardware logic device (71n) in each cell instantaneously verifies the percentage aperture position of its corresponding flow control valve (73n) and send a wireless signal (75n) to the to Global Coordinator software/hardware logic device (79).

The 2015 prototype comprises an overall flow rate sensor (19b) for instantaneously sensing the flow rate of the acid mist captured from a plurality of cells, and generating an electrical signal. Transducer (78) of the overall extraction flow rate converts the latter electrical signal into an electronic signal.

A Global Coordinator software/logic hardware device (74) receives and compares the sensed value of the instantaneous position of “% aperture” of the control valves in each cell and determines whether or not the positions are within the preset range of openings settings for the condition “Lowest Power Consumption” and sends an appropriate correction signal. The correction signal is applied via an electric current Frequency converter (78) to the variable speed source of suction (82).

The sensors for instantaneous individual extraction of acid mist flow rates (19a) from each cell and for instantaneous overall acid mist extraction flow rate (19b) can be: a rotameter, an orifice plate, a magnetic flowmeter, a Pitot tube, or any sensor that emits a reliable, accurate and stable signal as a function of the magnitude of physical gaseous fluid flow rate. The preferred device selected in the Prototype used is the Orifice Plate on account of its simplicity, precision, reliability and durability.

The transducers (70n) and (78) are any electronic device that converts the flow rate pressure differential signal emitted by the orifice plate sensor into an equivalent digital signal proportional to the physical differential pressure flow rate signal value.

The software/hardware logic device, (71n), and the coordinator device (79), can be any electronic circuit (hardware) containing a computer program, logic type (software), which compares the electrical signal emitted by the transducer, with a preset value (flow setting) in the device (71n). This software/hardware device can be a PLC, or any technical equivalent that may be available in the market, such as the RIEGEL FLUX CN1, or any specially designed device for this specific purpose.

The signal emitted by the software/hardware logic device, (71n), is sent to the actuator (72n) of the corresponding individual extraction flow rate control valve (73n), which by an electric or pneumatic signal increases or decreases the “% opening position” of the extraction flow proportional rate control valve (73n) of acid mist.

The extraction flow proportional rate control valve (73n), can be a valve: ball, needle, gate, butterfly or any technical equivalent that serves the purpose.

Testing Conditions and Test Results

The 2015 prototype system embodying the invention has been operated to date for over 7000 hours of continuous non-stop operation in an industrial copper electrowinning plant with an astonishing 100% operability. Verification of average H₂SO₄ vapor contents in the discharge flow of the suction turbine to open atmosphere are measured by means of a bubbler device (57a) installed in series with the global fluid flow discharged shown in FIG. 5.1)). The bubbler device (57a) continuously handles a small percentage of the total discharged fluid flow, bubbling the sample gaseous fluid in a measured amount of NaOH solution of known concentration through a given column height and determined by measured time taken to first discoloring of the NaOH solution (Reference OSHA 131).

The continuous operation of the Extraction System from the 4 cells yielded an average 0.03 mg/m³ of H₂SO₄ vapor in the final discharge to the open atmosphere, measured over 24 days of continuous operation. For reference, in Chile, DS 594 currently mandates a maximum average of 0.83 mg/m³ of H₂SO₄ in an 8 hr./day in the atmosphere of work areas inside tankhouse, and requires absolute compliance of compulsory use of respirator masks at all times inside the tankhouse.

Moreover, using the above-described prototype, it was also empirically determined that maintaining a slight depression stably (<2 mbar) in the confinement volumes for acid mist in each cell (operating at 700 meters above sea level) with a suction range from the extraction turbine of minus 0.8-1.2 cm (water column) is sufficient to sustain the condition of “Null Escape of acid mist from each cell” stably in time. The latter result is due to the use of the removable anodic cover (5) which is equipped with the double perimetrical acid mist seal (as shown in FIG. 3.5). The depression “window” relative to tankhouses atmospheric pressure allows for a “soft air” INFILTRATION from atmosphere INTO each hollow coalescer mini chamber, making it not only IMPOSSIBLE for the confined acid mist to escape to the working atmosphere, BUT ALSO slows the horizontal movements of the gaseous fluid volumes inside each mini chamber into the lateral channels of each cell. In fact, horizontal velocities of the gaseous fluid streams inside the confinement volume of each cell are of order of less than one (1) meter per second, which positively cannot entrain in suspension but the very small, un-coalesced droplets of electrolyte. The coalescence of droplets, and their growth in size (and weight), is further promoted by the turbulences generated in the meandering flow of the gaseous fluid in the confinement volume through the labyrinth of vertical surfaces obstacles provided by the electrodes inside the cell, the orthogonal flow change of travel direction (from the mini chambers into the lateral channels), enhancing, first, attachment of electrolyte droplets in the acid mist upon collisions with the plurality of vertical surfaces obstacles in their paths, and then, once removed from the moving gaseous flow, start coalescing into larger droplets at each point of attachment until sliding or falling by gravity back into the electrolyte, and never extracted from the cell!.

During two testing periods, the prototype was operated and the acid vapor concentration was measured in the depurated air discharged to atmosphere. The testing operations were carried out using minimum inflow volumes of air (from the tankhouses atmosphere) infiltrated into each cell and maintained in a range between 10% and 100% of the gaseous volume generated by a cell in its operating condition. The total gaseous volume being oxygen bubbles on the surfaces of insoluble anodes generated at the applied current density, and external air flow bubbling for soft aeration of the electrolyte. The flow rate in the prototype, having four (4) electrowinning cells of 33 anodes each, was less than 900 liters per minute, which was a maximum outside air infiltration equivalent to one time the volume of gases actually generated in each cell by its own operation. At this maximum flow, the prototype was effective at extracting acid mist at a 100% (undetectable) level from each cell, resulting in zero acid mist emission to the ambient work areas.

Moreover, gaseous fluid flow horizontal velocity of <1 meter per second which is insufficient to entrain airborne but the smallest droplets of electrolyte, enabling a most efficient and effective operation of the three—stage system for capturing acid mist and eliminating acid mist from the air, and optionally recycling of the treated acid condensate proposed in the present invention.

In effect, a system implementing the invention assures simultaneously in a stable and sustained manner over time—compliance with the essential environmental condition of “100% Null Escape of acid mist to the working atmosphere” “sustained 100% of the cell operating time”, simultaneously, with minimum use of electric power and innocuous levels of contaminants in the global depurated gaseous flow discharged to the open atmosphere.

In fact, the system implementing the invention was tested and certified as maintaining the condition of “Environmental Effectiveness” measured by the average maximum content of contaminant H₂SO₄ vapor (OSHA ID 131), in the final discharge to the atmosphere of the treated gaseous flows. The system implementing the invention requires minimal electric power usage. For example, a 0.5 Hp turbine was used to capture, confine and eliminate acid mist from the air stably during 7000 hours. An acid mist extraction system, in accordance with the invention was certified at less than 100 Watts/cell (0.13 Hp).

According to our testing results of the improved removable anodic covers (RAC) equipped with double horizontal flexible laminae in the perimetrical acid mist sealing system that provides controlled environmental air intake, operated with ad hoc differential pressure sensors allow monitoring in real time and controlling stably tankhouses ambient air infiltration flow rate in a “window” of ±1 millibars, positively guaranteeing the condition of “100% Null Escape of acid mist” by the firmware in the PAC that self regulates sustained “100% Null Escape” and “100% of the operating time”, and instantly setting off the respective alarms calling attention the instant when the depression falls outside of the “±1 millibars window”.

The RAC removable anodic covers in this invention have been specifically designed, tested and very successfully improved in order to substantially capture, confine, coalesce and recycle fine electrolyte drops right at each cell where they were generated along with recuperation and recycling of a portion of the other components of the acid mist such as fine electrolyte airborne droplets, water and H₂SO₄ all of which are recycled back to the cell electrolyte.

Control Strategy for Sustained “NULL Escape” with Minimum Energy and Innocuous Discharge to Atmosphere

The monitoring and programmable automatic controller system in real time of the Systems for Measurement, Control and Regulation of Extraction Flow Rates at the individual cell level and overall, global flow level of the Extraction System is designed to: ensure permanent and continuously sustained extraction flow settings in real-time in each cell are maintained at their corresponding preset values for each individual condition of “100% Null Escape of acid mist to the working environment”, including redundancy autoregulation of depression under the RAC system from each cell in the plurality of cells, while they are in operation, i.e, “100% of the operational time” real-time monitoring, control and regulation of the instantaneous variable frequency drive of the exhaust turbine to always seek in real time, the lowest frequency sufficient to provide overall suction demanded by the plurality of cells according to their individual extraction flows, in order for each to maintain its respective condition of “100% Null Escape of acid mist” set individually in each particular cell.

Real time monitoring of process variables such as electrolyte temperature are included with sensing devices at the infeed and overflow of the electrolyte to log the instantaneous temperature differentials of the electrolyte in crossing each cell, with ad hoc alarms to indicate whenever the differential is outside of the set minimum/maximum range.

To meet all the above consistently and steadily over time, it is essential to:

Determine, for each cell in particular, the minimum rate of extraction of acid mist that will ensure maintaining its condition of “Null Escape”, using either a differential manometer or an ad hoc differential pressure sensing system for positive detection of minimum safe levels of depression in the confinement volume of each cell indicating NO ACID MIST EMISSION to the environment, setting of alarms if safe levels are approached.

• • Individually, setting for each cell in the software/hardware device used a range of extraction flow rate values between 5-10% (or as required) in excess of the minimum flow rate of extraction determined for maintaining stably the condition “100% Null Escape of acid mist” to the working atmosphere
  • Individually for each cell, set the determined range of “% open position” of the control valves that achieve stably the condition “Minimum Power Consumption” (setting corresponding to the type of flow control valve used) in the devices for individual cell level, (5), and global plurality of cells (15) that corresponds to the extraction flow rate determined to maintain stably the condition of “100% Null Escape of Acid Mist” set in each individual cell.
  • The First System I of Individual Extraction Flow Control at the individual cell level allows maintaining permanently over time the extraction flow rate value setting for each cell operating as follows:

The extraction flow sensor, (83) in each cell (1), measures the instantaneous extraction flow rate which is of analogue physical nature, —where the individual flow rate transducer, (70n), transforms it into an electrical signal which is sent to the individual cell processing unit (71n), which upon comparing the instantaneous signal received with its own pre-set value, determines that they match, or do not match, and sends accordingly the appropriate correction signal to the actuator of the corresponding flow control valve, (73n), so that it always moves to its set value; the correction signal can be sent as wireframe or wireless.

• • The Second System II for Total Extraction Flow Control at the global extraction flow level of the number of cells connected to the Exhaust System is concatenated with the First system to operate in real time maintaining instantaneously the condition of “Minimum Power Consumption” operating as follows; each software/hardware logic device in the First System of Individual extraction flow from each cell (71n), sends an electrical signal, (74n), either hard wired or wireless, corresponding to the instantaneous position “% of opening” of each control valve, (73n), to the Coordinator Device, (79), which then verifies that the instantaneous position “of “% opening” is within the preset % range of opening (the value of the setting depends on the type of valve used); if the position “% opening” of any valve, (73n), is above its set range and all other valves, (73n), of the plurality of cells are operating within their set range, this means that there is a global deficit suction, which makes it necessary to supply by increasing the frequency of the current in the Frequency Variation to the drive that increases the speed of the turbine; conversely, if the instantaneous position of any valve, (73n), is below the range of its setting and all the other valves, (73n), are operating within range, then it means that it will be necessary to decrease the frequency of the current to the drive that ultimately reduces the speed of the turbine, which supplies the instantaneous overall net suction demand in the system for capturing acid mist and eliminating acid mist from the air, and optionally recycling the Acid.

During the setting of the software/relevant hardware devices used in a flow value of 5 to 10% in excess of the rate of minimum specific extraction to maintain the condition for “Null Escape” of individual acid mist from each cell, surprisingly, it was found that the “% openings” of valves should be set in the software/logic hardware devices in a range between 75% to 85% open to deliver the extraction flow rate for individual “Null Escape”, whereby the extraction flow generated by the suction turbine allows the software/logic hardware device, (15), to control the drive Frequency Variator of the turbine, from the start of the operation of the system for capturing acid mist and eliminating acid mist from the gaseous fluid, and optionally recycling the acid system, coming instantly and directly, to the joint simultaneous conditions of “Null Escape” and “Minimum Power Consumption” of the system for capturing acid mist and eliminating acid mist from the gaseous fluid, and optionally recycling the acid devices, and therefore “Minimum Electric Power” usage in the system for capturing acid mist and eliminating acid mist from the gaseous flow, and optionally recycling the acid Extraction System.

Method of Removing Acid from Air in Eiectrowinning Cells

FIG. 8 is a flowchart diagram representing method steps in the process of precluding/eliminating acid mist from one or more electrowinning cells, in accordance with an embodiment of the invention. Step 810 represents installing and operating the apparatus for capturing acid mist from each cell in electrowinning plant. Step 810 involves using the removable anodic cover, sealing the cover for maximum efficiency to trap the acid mist within the confinement volume, promote coalescence and apply a negative pressure (suction) that is adequate to create the proper fluid flow in order to carry the fluid to the depurator treatment apparatuses, control the flow with electronic measurements and adjustments of pressure and air circulation, and any other method steps involved in the operation of the system (described above).

Step 820 represents the method steps involved in removing the acid from the air captured in method 810. Eliminating acid involves carrying the captured fluids to a decantation tank. As described above, the captured fluids are run through a primary device, a depurator, for removing remaining acid mist from the captured gaseous fluid. The conditions for eliminating acid vapors from the captured fluids are created, maintained and controlled at a cell-by-cell basis. The output air of a depurator may be measured for quality standards. If the air meets the acid mist elimination standard i.e. clean air, then the air may be directly released into the atmosphere (e.g. step 830).

The condensate output liquid of a depurator may be considered “as useful” to the operation of the electrowinning cell, and may be recycled back into the electrowinning cell. In cases where advanced level of acid mist elimination is desired, embodiments of the invention may be implemented with successive/chained stages of acid mist elimination. Step 820 represents passing the output a depurator to a successive depurator, as represented by the dotted line and arrow.

Successive/chained two or more depurators may be a chain of similar depurators or may be designed for a specific outcome. For example, whereas a first depurator may comprise running the captured fluid through a water solution, a second, third etc. depurator may be designed as a multi-chamber depurator where acid condensation is controlled differently from the first depurator.

Step 840 represents the process of returning a portion or all of the recovered acid vapor from the acid elimination apparatus back in the electrowinning cells.

Step 860 represents the method of measuring several operation parameters (e.g., pressure, temperature etc.), comparing the measured parameters to a predetermined level that allows for reaching a desired outcome of the treatment, and actuating the pressure and temperature devices (e.g., pumps, resistors etc.) in order to stabilize operations.

Step 850 represents the method of coordinating operations between several electrowinning cells, and eventually controlling acid elimination from the captured fluids when treatment is carried out in one or more common depurators. The latter involves measuring operation parameters such as flow rate, pressure, temperature etc. computing control parameters and applying the control parameters to actuators for maintaining the stability of operations.

In light of what is described above, a person skilled in the art, may reproduce the present invention, to command exactly the same operation described, according to the number of individual cells connected to system for capturing acid mist and eliminating acid vapors mist from the air, and optionally recycling the acid, and thus implement the configuration of an ad hoc automatic control system for individual cell extraction flow rates concatenated in real time with its global extraction flow rate control system, as described.

Claims

1. A system for precluding air pollution in an electrodeposition tankhouse by capturing and processing byproduct gaseous fluids that emanate as a result of electrodeposition of nonferrous metals within electrolytic cells, said system comprising: an apparatus for confining a gaseous fluid as it is being originated by an electrowinning process within an electrolytic cell, wherein said gaseous fluid comprises at least an acid, fine airborne electrolyte liquid particles, contaminant gasses, and vapors of water and acid, wherein said electrolytic cell comprises a plurality of anodic and cathodic plates; an apparatus for removing said at least one acid, fine airborne electrolyte liquid particles, and vapors of water and acid from said gaseous fluid; and an apparatus for monitoring process variables in real time that allow controlling a plurality of concatenated operations, comprising a plurality of sensors for measuring gaseous fluid flow rates, differential pressures and other variables such as temperatures in said electrolytic cell and in said apparatus for removing said at least one acid, fine airborne electrolyte liquid particles, and vapors of water and acid, from said gaseous fluid, and a plurality of actuators for self-regulation of said variables.

2. A system according to claim 1, wherein said apparatus for capturing said gaseous fluid further comprises a plurality of removable covers each of which covers one of said anodic plates, complemented with fixed covers over both ends of the electrolytic cell.

3. A system according to claim 2, wherein each of said plurality of removable covers further having a monolithic body.

4. A system according to claim 3, wherein each of said plurality of removable covers having said monolithic body further is made of an anticorrosive high impact resistant, electric insulating material.

5. A system according to claim 4, wherein said anticorrosive high impact resistant electric insulating material is a reinforced vinyl-ester composite or equivalent high structural stress, impact resistant, anti-corrosive and electrical insulating polymer composite.

6. A system according to claim 2, wherein each of said plurality of removable covers further comprises a pair of longitudinal sealing elements (6) each of which is attached to a side of said each of said plurality of covers and extending all the way to contact both side walls of the cell, wherein each of said sealing elements is made of an acid-resistant flexible laminar transparent material and configured to prevent said gaseous fluid from escaping into said tankhouse by tightly coming in contact with an adjacent cathodic plate, and, when said adjacent cathodic plate is removed from said electrolytic cell, by expanding horizontally to come instantly in tight contact with an adjacent longitudinal sealing element of an adjacent removable anodic cover covering an adjacent anodic plate.

7. A system according to claim 6, wherein each of said plurality of covers further comprises, at each of a top end of said anodic plate, a first, a second and a third seal, wherein said first and said second seals, respectively, extend said pair of sealing elements to make a tight contact with an adjacent wall of said electrolytic cell, and wherein said third seal is configured to provide a seal around both extremities of a hanger bar of said anodic plate.

8. A system according to claim 1, wherein said apparatus for removing acid fine airborne electrolyte liquid particles, and vapors of water and acid from said gaseous fluid further comprises a first depurator for receiving said gaseous fluid extracted from said electrolytic cell.

9. A system according to claim 8, wherein said first depurator is further externally attached to an external wall of said electrolytic cell.

10. A system according to claim 8, wherein said depurator further comprises a water or liquid column of controllable height for bubbling said gaseous fluid and obtaining an acid condensate.

11. A system according to claim 10, whereir said depurator further comprises a discharge pipe located at the set height of the liquid column for flowing said acid condensate from said depurator back into said electrowinning electrolyte or electrolytic cell.

12. A system according to claim 11, whereir said first depurator further comprises an automatic device for refilling of a said liquid column to its set height

13. A system according to claim 1 comprising:

a plurality of electrolytic cells; a plurality of first depurators, wherein each one of said plurality of first depurators is connected to one of said plurality of said electrolytic cells with a pipe for receiving said gaseous fluid and obtaining a first acid condensate and a first depurated gaseous fluid; and a second depurator connected through a manifold with each of said plurality of said first depurators, and configured to obtain a second acid condensate and a second depurated gaseous fluid.

14. A system according to claim 13, whereir said second depurator further having at least one chamber.

15. A system according to claim 14, wherein said second depurator further having four vertically stacked connected chambers, wherein a bottom chamber is configured to receive said first treated gaseous fluid through said manifold connected to a bottom of said first chamber.

16. A system according to claim 15, wherein said four vertically stacked connected chambers having each at least one baffle plate, wherein said baffle plate further having a flat surface and inclined so as to increase linear travel distance and friction contact during the passage of said gaseous fluid.

17. A system according to claim 16, whereir at least one of said four chambers further comprises a turbulent bubbler device.

18. A system according to claim 16, whereir at least one of said plurality of chambers further comprises a set of cooling tubes optimally mounted to intercept an ascending gaseous fluid flow.

19. A system according to claim 18, further comprising an adequately sized chiller configured to condense acid vapors still remaining in said second depurated gaseous fluid so as to achieve any desired innocuous level in said acid vapors.

20. A system according to claim 16, whereir at least one of said four chambers is filled with a hygroscopic, absorbent or desiccating substances to capture remaining acid humidity or to remove any other corrosive contaminants that may be present in the gaseous fluid to safeguard the integrity of said electrolytic cell components or equipment such as cathodic plates, etc.

21. A system according to claim 1 further comprising a plurality of said electrolytic cell, wherein said apparatus for controlling said plurality of operations further comprising: a plurality of a first programmable automation controller configured to control a single one of said plurality of said electrolytic cells, wherein each of said plurality of said first programmable automation controller is configured to monitoring process variables in real time in each individual electrolytic cell of said plurality of electrolytic cells; and a second programmable automation controller configured for sustained concatenation and complex self-regulation of said plurality of said first programmable automation controller.

22. A system according to claim 21, whereir each of said first programmable automation controller is configured to minimize a use of suction power of an extraction turbine, while assuring reliable, sustained operation.

23. A system according to claim 21, whereir said apparatus for controlling said plurality of operations further comprises a pressure differential sensor acting as an auditor of health process safety, provides continuous monitoring ot said pressure underneath said covered electrolytic cell and an alarm system, wherein 2 millibars depression relative to working atmosphere in tankhouse is set to activate said alarm system any time depression in said electrolytic cell reaches 1 millibars; triggering an overriding signal to the cell or cells causing the alarm to immediately increase its or their extraction flows rates setting to set off the alarms.

24. A system according to claim 21, wherein said apparatus for controlling said plurality of operations is further configured to assure continuous operations of a remaining electrolytic cells when one or more electrolytic cells are disconnected or re connected from said plurality of said electrolytic cells.

25. A system according to claim 24, whereir said apparatus for controlling said plurality of operations is further configured to instantaneously re-establish operations maintaining their settings within a said plurality of electrolytic cells when said one or more electrolytic cells are reintroduced.

26. A system according to claim 24, whereir said apparatus for controlling said plurality of operations is further configured to instantaneously re-establish operations at their original settings within a said plurality ot electrolytic cells when an unpredictable power plant outages occur to their last settings pricr to the outage.

27. A system according to claim 1, wherein said apparatus for controlling said plurality of operations further comprises an electrolyte temperature sensing device comprising an infeed temperature sensor mounted at an electrolyte infeed point and an overflow temperature sensor located at an electrolyte overflow point, wherein a measured difference in temperature between said infeed temperature sensor and said overflow temperature is representative of an electrolyte temperature loss in circulating through said electrolytic cell in real time and triggers an alarm to reestablish the correct maximum/minimum temperature setting.

28. A system according to claim 1, wherein said apparatus for controlling said plurality of operations further comprises one or more sensors for measuring electric currents in said electrolytic cells, wherein said apparatus for controlling said plurality of operations is configured to receive an electronic signal from said one or more sensors for measuring electric currents and monitor the instantaneous current density flowing through each cathode in said electrolytic cell.

29. A system according to claim 28, whereir said apparatus for controlling said plurality of operations is further configured to monitor each cathode and issue an alarm if said current density gets outside the window of maximum/minimum acceptable set range of operational values.

30. A method of precluding air pollution in electrodeposition facilities by acid mist that is generated during the process of electrodeposition of non-ferrous metals, the method comprising the steps of:

confining a gaseous fluid being as it is beinc generated by an electrodeposition process within an electrolytic cell, wherein said gaseous fluid comprises an acid mist, wherein said electrolytic cell comprises a plurality of anodic and cathodic plates, and wherein said confining further comprises capturing said gaseous fluid within a plurality of hollow coalescer mini chambers (30a); over regular mini chamber (30b); removing said acid mist and acid vapor from said gaseous fluid; and controlling a plurality of operations by sensing a plurality of variables of a plurality of operation parameters,

wherein said plurality of operations include monitoring temperature, pressure and acidity levels within said electrolytic cell, comparing said plurality of values to a plurality of preset values, and emitting a plurality of electronic signals to act on a plurality of actuators for modifying said plurality of values to change toward said plurality of preset values.

31. A method according to claim 30, wherein said step of removing said acid vapor from said gaseous fluid further comprising:

applying suction so that a continuous and stable negative pressure results within said plurality of hollow coalescer mini chambers (30a) over regular mini chamber (30b);for extracting said gaseous fluid to a first depurator and precluding said gaseous fluid from escaping from said electrolytic cell into an ambient air surrounding said electrolytic cell; and bubbling said gaseous fluid through a water or liquid column of given height within said depurator diluting said acid vapor in said liquid column for obtaining a first acid condensate, and for substantially reducing a presence of said acid vapor in a first resulting gaseous fluid.

32. A method according to claim 31 further comprising bubbling said gaseous fluid with water or a liquid column containing a basic solution of a given height for capturing said acid vapor or other contaminants entrained in the depurated gaseous flow.

33. A method according to claim 31, wherein said step of removing said acid vapor from said gaseous fluid further comprising: sensing contents of said acid vapor in said first gaseous fluid for determining a concentration in said first resulting gaseous fluid; releasing said resulting gaseous fluid into an ambient air if said concentration is below a predetermined release level.

34. A method according to claim 31, wherein said step of removing said acid vapor from said gaseous fluid further comprises feeding back said first acid condensate into said electrolytic cell.

35. A method according to claim 31, wherein said step of removing said acid vapor from said gaseous fluid further comprising: carrying said first resulting gaseous fluid from at least one of said first depurator to a second depurator, wherein said second depurator having a plurality of chambers, wherein at least one of said chambers is for condensation of vapors in the gaseous fluid flow, and wherein said first resulting gaseous fluid is ascendingly carried through said at least one condensation chamber; and intercepting said first resulting gaseous fluid within said at least one condensation chamber by a plurality of optimally mounted cooling tubes for cooling said first resulting gaseous fluid and producing a second acid condensate and a second resulting gaseous fluid.

36. A method according to claim 35, wherein said step of removing said acid from said gaseous fluid further comprises feeding back said second acid condensate into at least one of said electrolytic cell or electrolyte discharge, and releasing said second resulting gaseous fluid into an ambient air.

37. A method according to claim 30, wherein said step of controlling said plurality of operations further comprising controlling a flow rate of said gaseous fluid, a flow rate of said first resulting gaseous fluid and a flow rate for said second gaseous fluid.

38. A method according to claim 30, wherein said step of controlling said plurality of operations further comprising for continuously monitoring said pressure inside the gaseous fluid confinement volume in said electrolytic cell by sensing a pressure differential and issuing an alarm, wherein 2 millibars depression relative to working atmosphere in tankhouse is maintained and said alarm is activated any time depression in said electrolytic cell reaches 1 millibars.

39. A method according to claim 30, wherein said step of controlling said plurality of operations in a system having a plurality of said electrolytic cells, further comprising maintaining individually said operations settings in a remaining set of electrolytic cells when one or more electrolytic cells are dismissed from said plurality of said electrolytic cells.

40. A method according to claim 39, wherein said step of controlling said plurality of operations in a system having a plurality of said electrolytic cells, further comprising instantaneously re-establishing said operations at their individually settings within a said plurality of electrolytic cells when said one or more electrolytic cells are reintroduced.

41. A method according to claim 30, wherein said step of controlling said plurality of operations in a system having a plurality of said electrolytic cells, further comprising in unpredictable power outages events, instantaneously re-establishing operations at their last individual settings prior to the outage within said plurality of electrolytic cells when the power is reestablished.

42. An apparatus for precluding air pollution in an electrodeposition tankhouse by capturing and processing byproduct gaseous fluids that emanate as a result of electrodeposition of nonferrous metals within electrolytic cells, said system comprising:

a plurality of flexible laminae wherein a plurality of pair of said plurality of said flexible laminae, each of which form a double longitudinal seal (6); and

a plurality of hollow coalescer mini chambers (30a), each of which formed by one pair of said plurality of pairs of said flexible laminae, wherein each of said plurality of hollow coalescer mini chambers having a roof and a bottom and wherein said roof is cooler than said bottom, and wherein vertical movement of both continuous double longitudinal seals (6) upon extraction/re insertion of cathode plates (4) detaches coalesced electrolyte drops from the surfaces of the double longitudinal seals (6).