Abstract: Off gases from black liquor heat treatment, evaporators, wood pulp digesters, etc. are treated to produce primarily hydrogen sulfide and sulfur free fuel gases such as methane, carbon monoxide, hydrogen, and ethylene. Then the hydrogen sulfide is used to produce sodium polysulfide in white liquor for cooking wood chips to produce pulp by the kraft process. Polysulfide may be formed in three different ways: by supplying air to a fuel cell into which white liquor and the hydrogen sulfide containing gas have been introduced; by bringing clarified white liquor and hydrogen sulfide containing gas into contact with a wet-proofed activated carbon catalyst and oxygen containing gas; or by bringing unclarified white liquor into contact with the gas and oxygen containing gas, with lime mud acting as a catalyst, and then clarifying the polysulfide-rich white liquor produced to remove the lime mud. The white liquor produced contains about 0.5-8% on wood sodium polysulfide.

Abstract: In gold and/or silver cyanide leaching-adsorption processes employing solid adsorbents such as activated charcoal, the overall efficiency in the recovery of gold and/or silver from ores or the like is greatly increased by contacting the cyanide slurry containing the gold and/or silver, with oxygen gas instead of normal air. A generally pure oxygen gas can be bubbled into a vessel containing the slurry, and a cover (e.g. a floating cover) may be provided on the vessel to reduce the oxygen transfer out of the solution and to facilitate pressurization of the system with an oxygen atmosphere. The procedures of the invention are applicable to carbon-in-pulp (CIP), and carbon-in-leach (CIL) processes and related processes using resins. Deaeration of the ore slurry can be practiced prior to the introduction of the oxygen.

Abstract: A method and apparatus provide for the production of low kappa number (e.g. below 20) kraft paper pulp, and a low viscosity black liquor which is easily transported to a recovery or disposal stage. Comminuted cellulosic fibrous material is steamed, passed to a treatment vessel, and then introduced into the top of a continuous digester. Black liquor is withdrawn from the digester and heated about 20-40 degrees C. above cooking temperature (e.g. about 170 degrees C.), and then introduced into contact with the material in the treatment vessel. After the material is treated with the black liquor, it is withdrawn from the treatment vessel, and passed to the recovery or disposal stage. White liquor may be introduced into the treatment vessel after black liquor withdrawal, after passing in heat exchange relationship with liquid recirculated from an impregnation vessel to a high pressure feeder.

Abstract: Compressible material is compacted into a plug by a device including a housing, solid outer wall, and restricting adjustable portion at an outlet. A root wall is rotated about an axis and conveys the material to be compressed in a channel having solid sidewalls. Without significant extraction of liquid from the material, the material is compressed until discharged in a compacted plug form from the housing outlet. A pneumatic cylinder provides an adjustable force for effecting the compaction adjacent the housing outlet. Examples of compressible materials that may be acted upon in the practice of various industrial processes include wood chips, high consistency paper pulp (cellulose pulp), wax and fibrous waste (for making artificial fireplace logs), and mud and straw (for producing building blocks or bricks).

Abstract: In a dewatering press having a number of rotors rotatable in a cylindrical press housing with an inlet channel defining an inlet for a humid mass into the housing, a mechanism for equalizing the amount of mass fed to the inlet channels. A screw feeder is associated with each inlet channel, and equalization is accomplished by providing opening communication between the screw feeders at their pressure ends, adjacent the inlet channels. A module having a conduit associated with each inlet channel, and a cross over tunnel at the portion of the module adjacent the press housing, is disposed between the feeder screw housing and the press housing.

Abstract: Nozzle breakage in an atmospheric diffuser for treating paper pulp is precluded by mounting the nozzle to the rotating scraper arm by a connection which will break when the nozzle is subjected to a drag force of about 50% of the force that will break the nozzle. The connection preferably includes a pivot connection of a nozzle extension at one side of the arm, and a shear pin connection of the extension at the end opposite the pivot connection. An oblong nozzle is integral with the nozzle extension, with the fluid introducing openings of the nozzle remote from its connection to the extension. The amount of pivotal movement of the nozzle when the shear pin breaks is limited to about 15.degree.-26.degree. so as to prevent the nozzle from contacting an annular extraction screen of the diffuser.

Abstract: In a pressure diffuser, clogging of the tapered inlet passageway at the bottom of the vessel is minimized by providing a number of lubricating fluid introducing nipples disposed circumferentially around the annular passageway. The nipples introduce lubricating fluid so that it flows upwardly along the inner wall of the vessel. The vessel inner wall and the bottom support for the screen at the passageway are polished and free of projections, so that friction is minimized. The nipples are provided in sets that are staggered so that a nozzle is placed about every 15.degree. around the circumference of the vessel, and a common annular header--mounted on the support legs of the vessel--provides the lubricating fluid. Should screen movement slow as a result of paper pulp properties near the screen bottom support, the flow rate of lubricating liquid can be increased so as to significantly dilute the pulp at the passageway until slow movement of the screen is overcome.

Abstract: In an atmospheric diffuser for the treatment of paper pulp (thickening, bleaching, and/or washing) the flow of backflushing liquid is controlled so as to maximize the effective treatment of the pulp. The pulp passes upwardly in a vessel. A number of annular screen assemblies are provided, with at least one screen associated with each screen assembly. The lower screen includes a barrier wall with a passage in the barrier wall adjacent the bottom end of the screen. Liquid which flows through the screen must flow to the passage in order to be withdrawn from the vessel, as the screen is slowly moved upwardly. When the screen is rapidly moved downwardly to cause backflushing, the backflushing liquid at the top end of the screen is liquid that recently passed through the screen at that point, so the pulp at that point --which is the cleanest along the length of the screen--has a minimal chance of being contaminated.

Abstract: In a hydrocyclone, particularly for deinking of paper pulp, a movable generally cylindrical plug is utilized to define an annular space near the accepts withdrawal conduit to effect release of obstructions should the annular space become clogged. The plug is biased by a spring, and moved against the spring pressure to enlarge the annular space automatically in response to a build up of back pressure. The plug also may be moved manually from exteriorly of the hydrocyclone housing, or may be operated by fluidic elements on a periodic basis to clean the annular space whether or not there has been a build up of back pressure. The hydrocyclone preferably is a gas sparged hydrocyclone, and recycled paper--with print on it--having a consistency of at least about 2% is treated to effect deinking.

Abstract: A continuous, upright, digester for paper pulp is utilized as a structural support for accessory vessels, such as a chip bin and flash tanks. Generally horizontal steel beams are connected to the digester and extend outwardly from opposite sides of the digester vessel. One set of beams is connected to the impregnation vessel, and supports the chip bin on them. A steaming vessel may be mounted on a horizontal platform below the chip bin. On the opposite side of the digester, the second horizontal beams extend to a pair of vertical legs spaced apart approximately the diameter of the digester. First and second flash tanks, one above the other, are supported by the second set of horizontal beams, and a third set below the second set, those beams--and structures connected to them--being the only support for the flash tanks.

Abstract: Organic constituents in a liquid, such as a waste water from a municipal or industrial process (e.g. bleach plant extraction liquor from the bleaching of paper pulp) may proceed effectively without the addition of alkali. When the organic constituents are reacted with an oxygen containing gas at appropriate pressure and temperature conditions, oxidized organics and gaseous acidic products of oxidation (e.g. CO.sub.2) that are produced are continuously and immediately removed from the liquid so that they do not significantly contribute to lowering of the pH of the liquid, so that the reaction may proceed and the liquid remain alkaline.

Abstract: The proper pressure conditions are maintained within an atmospheric pre-steaming chips bin used in the production of paper pulp. Extending upwardly from the top of the chips bin is a vertical section of conduit, an elbow section, and a horizontal section. A door guide with a door opening in it is disposed in the horizontal section and precludes passage of gas through the horizontal section except through the door opening. A pivot pin mounts a door at its top so that it normally assumes a vertical orientation closing off the opening, and it is adjustably biased into that orientation by a counterweight mechanism. The counterweight includes weight discs which mount on a vertical section of rod having external screw threads, and a horizontal section of rod is connected by a flange to a flange of the pivot pin.

Abstract: Evaporation of saline water in a desalinization process, or evaporation of other types of liquid such as black liquor from paper pulp processing, is accomplished utilizing a multiple effect evaporator. Each effect includes one or more (e.g. first and second) sets of horizontally elongated dimpled plate evaporator elements. Horizontally flowing heating fluid, such as steam, is introduced to the internal passage of at least the second set in all the effects, and a head of circulation liquid is provided to cause liquid being evaporated to flow downwardly from the head over the external surfaces of the sets of dimpled plates in a thin film. The vapor evaporated is drawn through a demistor and is used as the heating fluid for the next effect. Recirculating liquid that has not evaporated and liquid separated by the demisting process are recirculated to the head associated with each effect. Clean condensate--such as distilled water--is withdrawn from the last effect.

Abstract: A multi-stage flash evaporator is constructed so that the evaporator elements are dimpled plates mounted so that they extend horizontally. One, two, or more sets of plates may be mounted in each evaporator stage, the sets stacked upon one another in a tier arrangement. Each stage may be formed by a circular cross-section vessel, with I-beams--or like supports--extending horizontally at about the horizontal diameter of the vessel, and supporting the dimpled plates on them. A condensate collection trough is mounted below the dimpled plates and at the I-beams, the I-beams having openings in them through which condensate collected by the trough passes from one end of the vessel to the other. The hot liquid --such as sea water to be desalinated--to be evaporated is passed into a bottom chamber of each stage vessel, with vapor flowing upwardly through demistors and channels, into contact with the dimpled plates, and the condensate falling as a thin film down the plates and collecting in the condensate trough.

Abstract: The removal of sticky contaminants during the production of recycled paper is accomplished utilizing a hydrocyclone froth flotation process. Paper having sticky contaminants from labels, tapes, hot melts, and other tacky substances, is reduced to a finely comminuted liquid solids suspension of about 1-4% consistency. The suspension is introduced into a first end of a vortex in a hydrocyclone, and the air is sparged radially inwardly into the suspension vortex by passing it through a porous inner wall of the hydrocyclone. Ligher weight sticky contaminants move to the center of the hydrocyclone, facilitated by the radially inward movement of the sparging air, and hydrophobic sticky contaminants attach to the air bubbles and form a foam. The foam and lightweight sticky contaminants are removed from the first end of the vortex, while the pulp which has had sticky contaminants removed therefrom is discharged from the second end of the vortex, opposite the first end.

Abstract: A hydrocyclone establishes a first vortex of fluent material at one end (e.g. in a top portion), and a second vortex at the other end (e.g. in a bottom portion). The first vortex is established within a porous surface of revolution to which gas or other fluid is supplied, passing through the porous surface into the first vortex. The second vortex is established by a conical end section extending outwardly from (e.g. below) the porous surface, and with an axial (e.g. bottom) discharge for fluent material. Some fluent material--for example having heavy particles--is removed tangentially from the conical end section at a portion near the porous surface of revolution. A conical shroud having a circumferential periphery is mounted by a number of spaced legs connected between the shroud and the conical bottom section so that fluent material may pass between the circumferential periphery of the shroud and the porous surface of revolution.

Abstract: In an atmospheric diffuser for the treatment of paper pulp (thickening, bleaching, and/or washing) the flow of backflushing liquid is controlled so as to maximize the effective treatment of the pulp. The pulp passes upwardly in a vessel. A number of annular screen assemblies are provided, with at least one screen associated with each screen assembly. The lower screen includes a barrier wall with a passage in the barrier wall adjacent the bottom end of the screen. Liquid which flows through the screen must flow to the passage in order to be withdrawn from the vessel, as the screen is slowly moved upwardly. When the screen is rapidly moved downwardly to cause backflushing, the backflushing liquid at the top end of the screen is liquid that recently passed through the screen at that point, so the pulp at that point--which is the cleanest along the length of the screen--has a minimal chance of being contaminated.

Abstract: The waste heat from a steam turbine is condensed and used to desalinate sea water at the same time. The waste steam from a turbine is fed to a condenser through which cold sea water passes. As the cold sea water condenses the waste steam, it is warmed. It is then introduced into a first chamber which includes a number of spray heads disposed over fill (packing) that acts as an evaporator. Any water not evaporated is collected in a sump at the bottom of the first chamber, and the evaporated vapor is passed upwardly under the influence of a fan and ultimately to a second chamber. The second chamber may either be stacked above the first chamber, or in side-by-side relationship with it. A condenser, such as a number of dimpled metal plates, or plastic membranes defining a closed loop, or another set of spray heads and fill, are provided in the second chamber. Air typically recirculates from the bottom of the second chamber back into the first chamber.

Abstract: The number 2 flash tank of a black liquor energy recovery system associated with a continuous pulp digester is eliminated, and other advantages are obtained. After flashing in the number 1 flash tank, concentrated black liquor passes to a multiple effect evaporator system as the heating fluid supplied to the last effect. The heated black liquor passes in heat exchange relationship with excess make-up liquor from the high pressure feeder circulation system and/or with portions of the extracted black liquor that have had more of their content removed, the heated black liquor effecting evaporation of the excess make-up liquor and/or portions of the black liquor. Steam from the steam relief of the steaming vessel may be used as a secondary heating fluid source for the first effect.

Abstract: Deinking of paper having print during the production of recycled paper is accomplished by a froth flotation process using a hydrocyclone. A finely comminuted liquid solids used paper suspension having a consistency of about 1 to 4% is introduced into a generally vertical axis vortex provided in a hydrocyclone. Air is sparged into the suspension in the vortex, by passing through a porous inner wall of the hydrocyclone, to cause ink particles to attach to the air bubbles and to rise in a foam while cellulosic pulp moves downwardly in the vortex. The foam--containing the ink particles--and the pulp are removed from the vortex in separate streams. The pulp is deaerated and the air component of the foam is removed in the cyclone. About 5-15% of the total flow of the suspension is removed with the foam in each stage, and about 95-85% with the pulp.