Abstract: A method of producing a cobalt plated electrode is disclosed. The method comprises subjecting an electrically conductive substrate to electrolytic plating in an aqueous bath containing cobalt ions and a reducing agent selected from the group consisting of hypophosphite salts, phosphite salts, formaldehyde and hydrazine in the concentration of 2 to 100 gpl. Ammonium ions and a weak complexing agent are preferably added to the bath. The current density is in the range of 0.2 to 150 mA/cm.sup.2 and the temperature of the bath between 20.degree. and 80.degree. C.

Abstract: An apparatus for detecting the presence of a specific substance in a gas stream is disclosed.

Abstract: An apparatus for measuring the sedimentation characteristics of particulate solids in liquid is disclosed. The apparatus comprises two separate vertical housings adapted to be filled to the same level with a liquid less dense than the particulate solids to be measured, means for introducing a sample of particulate solids to be measured in one of the housings, two pressure sensors located at the same level, one in each housing, and a differential pressure transducer connected to such pressure sensors for sensing the differential pressure caused by the sample introduced into one of the housings. The differential pressure transducer provides an output indicative of the weight percent of sample remaining in suspension as a function of time and such output may be used to determine the weight fraction of the particulate solids passing any given mesh size, or for measuring the specific gravity of particulate material of known dry weight.

Abstract: A method is provided for purifying zinc sulphate solutions containing copper, cadmium and cobalt impurities, which comprises, in a first stage, treating the impure zinc sulphate solution with zinc dust and an antimony and/or arsenic compound so as to form a cement containing essentially all the copper and cadmium and a portion of the cobalt and separating this cement from the partially purified solution, then, in a second stage, treating the partially purified solution with zinc dust and an antimony and/or arsenic compound to form a cement containing essentially metallic zinc as well as the remaining cobalt and other incidental impurities and separating this cement from the purified solution and recycling at least the major portion of this cement to the first stage where it is used instead of zinc dust to effect further treatment of a fresh impure zinc sulphate solution. The purified solution from the second stage may also be subjected to a third purification stage for control purposes.

Abstract: A method is provided for removing arsenic from arsenic and copper containing electrolytes by electrolysis while minimizing or substantially reducing the formation of arsine gas, through the application of a periodically reversed or interrupted current during such electrolysis. The method is particularly suitable for the purification of copper refinery electrolyte.

Abstract: A process and an apparatus for electrowinning metal from metal bearing solutions is disclosed. A support solution containing a predetermined metal concentration is continuously recirculated through a cell having a porous grid supporting a bed of particulate conducting particles at a sufficiently high flow rate so as to fluidize and expand the bed by 5 to 25%. A gas is continuously fed through the bed of conducting particles so as to strongly agitate the particles at low bed expansion to maintain good mixing and uniform fluidization of the bed of particles. The cell includes an electrode arrangement suspended from the top of the cell and immersed into the bed of fluidized conducting particles.

Abstract: A device for measuring the density of a liquid or of a suspension of solids in a liquid comprises a holder of predetermined length, two pressure sensors mounted at one end of the holder and adapted to be submerged so that the two sensors are vertically at predetermined levels apart in the liquid, and a differential pressure transducer also mounted on the holder and coupled to the pressure sensors for providing an output voltage proportional to the pressure differential sensed by the pressure sensors.

Abstract: A novel group of corrosion inhibiting pigments has been discovered, which is based on zinc molybdate compounds selected from sodium zinc molybdate, potassium zinc molybdate, ammonium zinc molybdate and mixtures thereof, combined with a suitable carrier, so that the proportion of the zinc molybdate compound is such that the Mo content in the pigment is between about 1 and 30% by weight. Such pigments can be prepared in situ by several methods, such as a double decomposition reaction of sodium, potassium or ammonium molybdate and a solution containing dissolved zinc ion, or an addition of an appropriate acid to zinc oxide dispersed in sodium, potassium or ammonium molybdate solution, or an addition of zinc oxide to a solution which comprises molybdic oxide dissolved in an aqueous solution of sodium, potassium or ammonium molybdate.

Abstract: A process for electrowinning of copper from leach solutions containing a high concentration of iron in the range of about 5 to 40 gpl, is disclosed. The process consists in applying direct current through the solution and periodically reversing the polarity of such current to obtain a solution having a low ferric ion concentration, thereby increasing the operating current efficiency and consequently decreasing the power consumption.

Abstract: A method is disclosed for removing arsenic by solvent extraction from a copper and/or nickel bearing aqueous solution containing about 100 to 600 gpl sulphuric acid. The method comprises contacting the solution with an organic solution consisting of about 5 to 80% by volume of tributylphosphate in an organic diluent, and subsequently stripping the arsenic from the loaded organic solution with a suitable stripping agent. Particularly, when the sulphuric acid concentration in the aqueous solution is lower than 300 gpl, the organic solution advantageously comprises up to about 15% of a quaternary ammonium reagent. Preferred quaternary ammonium reagents are tricaprylmethyl ammonium chloride and mixtures of tri-C.sub.8 -C.sub.10 methylammonium chlorides.

Abstract: A silencer for use with a tuyere puncher is disclosed. The silencer comprises a chamber having a front face and a rear face provided with a central opening for passing of the punch bar operated by the puncher, a plurality of closure members located in the rear portion of the chamber and mounted for movement toward and away from the longitudinal axis of the chamber and including means for forcing the closure members against the periphery of the punch bar so as to form a seal between the closure members and the punch bar, and a seal secured to the front face of the chamber for engaging the tuyere to seal such a tuyere before penetration of the punch bar through the tuyere valve. The silencer is mounted on a mobile table which is supported by the puncher and operated in synchronism with the punch bar.

Abstract: An electrode having good conductivity, low oxygen and chlorine overvoltage and a low corrosion rate under electrolysis conditions is disclosed. The electrode comprises an electrically conductive substrate made of a material resistant to the electrolyte and the electrolytic products, coated on at least a portion of the surface thereof with a basic coating of a material containing 30-70% by weight of an acid insoluble metal tungstate, 15-60% by weight tantalum pentoxide and 5-15% by weight of a noble metal oxide.

Abstract: A magnetic testing device for detecting defects in elongated objects is disclosed. The testing device comprises a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated object for inducing a longitudinal magnetic flux in a section of the object between the poles of the magnet assembly which is strong enough to saturate such section of the object, a tubular pole piece substantially centered on the elongated object adjacent each pole of the permanent magnet assembly for directing the magnetic flux radially into the object at one pole and out of the object at the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the radial flux entering into the elongated object, and means for sensing the variations of such magnetic flux as an indication of loss of metallic area in the object.

Abstract: It has been found that esters and polyesters of thioglycolic acid, which form a protective, water insoluble complex with zinc atoms, are suitable for inhibiting wet storage staining and the formation of white rust in zinc and zinc coated materials. Many of these compounds are new products.

Abstract: A method for the oxidation of organic material present in concentrated sulfuric acid is disclosed. The method comprises the steps of diverting a portion of a concentrated sulfuric acid stream, diluting the diverted stream with water to about 40-70% sulfuric acid concentration, passing the diluted stream through an electrolysis apparatus to oxidize some of the sulfuric acid to form a predetermined quantity of peroxosulfuric acids, and returning the diverted stream back to the main stream to oxidize the organic material and decolorize the main stream of concentrated sulfuric acid.

Abstract: A method is provided for removing arsenic from arsenic and copper containing electrolytes by electrolysis while minimizing the formation of arsine gas, through the application of a periodic reverse current during such electrolysis. The method is particularly suitable for the purification of copper refinery electrolyte.

Abstract: A froth level monitor is disclosed. The froth level monitor comprises a plurality of electrically conductive electrodes spaced in the vertical direction and adapted to contact the top of the froth in sequence as the level of the froth rises, a constant current source connected to each electrode and capable of generating a constant current when its associated electrode is in contact with the froth, and a summing and time averaging current to voltage converter connected to the output of all the constant current sources for summing up all the currents as an indication of the number of electrodes in contact with the froth and for averaging with respect to time the variations in froth level so as to provide an indication of the mean level of the froth.

Abstract: A spring box assembly for use in clamping mechanisms of the over-center type comprises two nested metal housings, at least one spring located between such housings, and means for resiliently holding said housings together with a predetermined initial tension applied to the spring. In a preferred embodiment, at least one metal pin is secured at one end to the bottom of the inside housing and slip fitted in holes in the outside housing at its other end, a helical spring is located around such pin and means are mounted on the other end of such pin for holding the two nested housings together with a predetermined initial tension applied to such spring.

Abstract: Slimes from electrolytic copper refinery are first treated by leaching them with dilute sulphuric acid under an oxygen partial pressure of up to 50 psi and an elevated temperature, until copper and tellurium present in the slimes are substantially dissolved, and effecting a liquid-solid separation of the leached slurry so produced to separate the leach liquor from the leach slimes. The leach liquor is then treated with metallic copper to cement the tellurium as copper telluride. The latter is separated from the remaining solution which is suitable for the production of copper sulphate. The leach slimes containing mainly selenium, lead, silver, gold and other impurities are dried, mixed with a binder and pelletized and the pellets are then roasted to remove selenium as selenium dioxide. Finally, the roasted pellets are smelted to remove the remaining impurities leaving a dore metal containing essentially silver and gold.

Abstract: A process for controlled slow cooling of non-ferrous smelting slags, such as copper slags, for the recovery of the non-ferrous metals contained therein by subsequent crushing, milling and flotation operations is disclosed. The process comprises the steps of pouring the molten slag into a ladle, allowing the slag to slowly cool and solidify in the ladle at least to the point where a shell is formed which is strong enough to withstand dumping from the ladle, dumping the slag from the ladle in a single piece, allowing the dumped slag to cool until its center is substantially solidified, and breaking the dumped slag in small pieces for further cooling, crushing, milling and flotation operations. Alternatively, the top of the slag in the ladle may be water cooled while the slag is allowed to slowly cool in the ladle until its center is substantially solidified. The slag is then dumped and subsequently broken in small pieces.