Abstract: A method for controlling the electro-deposition of metal from an aqueous electrolyte containing two organic polarizing agents is disclosed. The method requires measuring the nucleation overpotential, the plating overpotential, and the difference between these potentials. By relating these measurements to predetermined values, optimum process control can be obtained by changing the concentration of the various organic polarizing agents in the process electrolyte.

Abstract: A method and apparatus for effecting periodic current reversal in metal electro-deposition processes are disclosed. By using a circuit in which the current always flows in the same direction through a filter reactor, regardless of the current flow through the electro-deposition cell, faster reversal switching times are obtained. The overshoot and AC ripple encountered on current reversal are also decreased.

Abstract: Improvements in the bipolar refining of lead are described, comprising maintaining a high current density controlled at a value such that the anode overvoltage will not exceed the value at which impurities dissolve and which is related to the internal resistance of the cell, together with periodic reversal of the polarity of the current applied to the electrodes. These improvements result in improved cell efficiency and in the formation of strong, coherent lead deposits which are easily stripped by mechanical means.

Abstract: In the processes for the production of solid particulate sulfur by prilling or granulation, wherein molten sulfur emanates from a spray means, such as a prilling device or spray nozzle, interruptions occur in the flow of sulfur from the spray means. The uneven flow of molten sulfur from a spray means can be substantially eliminated by applying vibration to the spray means, preferably in the diection of flow of molten sulfur through the spray means, at a low frequency in the range of 0.2 to 30 cycles per second. The molten sulfur emanating from the spray means is at a temperature of at least one Celsius degree above the melting temperature of sulfur and under a pressure of at least 250 Pa. The flow rate of sulfur from the spray means is uniform and steady, the particulate sulfur product is hard and closely sized, and the emission of sulfur fines discharging from the process is reduced.

Abstract: A method for the heat treatment of cadmium mercury telluride homogeneous single crystals is disclosed wherein the crystals are heated and maintained at a temperature in the range of from about 300 K to below the solidus temperature of the composition treated in the presence of mercury, the vapor pressure of mercury being less than the saturation vapor pressure of mercury.

Abstract: A process for the beneficiation of lead or copper-lead sulphide ore or concentrate containing calcium and magnesium carbonates wherein the ore or concentrate is conditioned with a limited amount of sulphuric acid to form an acidic slurry and subjecting the acidic slurry to froth flotation whereby an upgraded concentrate and a tailing comprising calcium and magnesium sulphate are obtained.

Abstract: In the process for electrowinning of zinc from acid zinc sulfate electrolyte, electrolyte is recirculated to the cells and a portion of the electrolyte is returned to the leaching operation of zinc-bearing material. By only returning electrolyte that overflows from electrolytic cells that contain new and/or recently cleaned anodes to the leaching operation, the amount of sludge in the cells can be reduced, the period between cleanings of cells can be lengthened and the amount of addition agent for controlling the lead content of deposited zinc can be reduced. Electrolyte overflowing from only those cells that contain new and/or recently cleaned anodes is diverted and kept separate from recirculating electrolyte from all other cells by providing separate means for collecting and transferring electrolyte to the leaching operation.

Abstract: A process is disclosed for the production of a urea sulfur fertilizer by mixing urea and molten sulfur to obtain a molten mixture and solidifying the molten mixture to obtain a homogeneous, solid, particulate urea sulfur fertilizer wherein the sulfur has particle sizes of smaller than about 100 micron. The process comprises passing molten urea and molten sulfur through a mixing device at a temperature above the melting points to produce a finely divided sulfur dispersed in urea with the molten sulfur added in amounts sufficient to produce said urea sulfur fertilizer, maintaining a pressure drop across said mixing device of at least about 200 kPa to form a homogenized melt of urea sulfur, and solidifying said homogenized melt by prilling or agglomeration.

Abstract: A method is described for attaching a preformed solder ring to a cover used to hermetically seal a container for a semiconductor device. The surface of the preformed solder ring that engages the cover is caused to melt and bond to the cover on solidification while the opposite surface of the ring is maintained relatively cool in a solid state by abutment against the flat surface of a cooling block.

Abstract: A method and apparatus for controlling a process for the electrodeposition of metals using electrolyte containing concentrations of impurities and addition agents that affect polarization. The method and apparatus include a test circuit comprising a test cell, a sample of electrolyte, a moving cathode, an anode and a reference electrode immersed in said sample, a constant current source and measuring means electrically connected to the electrodes. A controlled low current is applied to the electrodes in the test cell to measure the activation overpotential between the cathode and the reference electrode. The activation overpotential is measured at the point of inchoate deposition of the metal and is related to the concentration of impurities and polarization affecting agents in the sample. The processes for the purification of electrolyte and the electrodeposition of metals are subsequently adjusted in relation to the measured value of the activation overpotential to obtain optimum metal deposition.

Abstract: A method and an apparatus are disclosed for forming expanded mesh sheet from deformable strip by the steps of concurrently slitting and preforming the strip to provide transverse bands of slit and elongated wire segments projecting alternately from opposite sides of the plane of the strip separated by transverse bands of unslit strip, slitting the strip at alternate bands to extend slit segments in a staggered relation and laterally expanding the slit and preformed strip. Concurrent slitting and preforming and subsequent slitting can be effected by a cluster of three rolls or by a linear arrangement of pairs of opposed rolls.The invention has particular utility in forming expanded mesh sheet of exact final dimensions for use as battery grids from lead or lead alloy strip.

Abstract: A method of forming elongated slit segments in deformable strip includes concurrently slitting and preforming the strip by intermeshing substantially convexly shaped tool surfaces each having a linear leading portion and a linear trailing portion joined by a rounded apex portion. The linear leading and trailing portions are collinear with and generally define portions of the sides of a triangle which has a base with a length equal to the length of the strip being slit. The length of the side of the triangle corresponding to and collinear with the leading portion is less than the length of the side of the triangle corresponding to and collinear with the trailing portion, and the angle formed between the side of the triangle corresponding to the leading portion and the base is not greater than 90.degree..

Abstract: A method and an apparatus are disclosed for forming expanded mesh sheet from deformable strip by the steps of concurrently slitting and preforming the strip to provide transverse bands of slit and elongated wire segments projecting alternately from opposite sides of the plane of the strip separated by transverse bands of unslit strip, slitting the strip at alternate bands to extend slit segments in a staggered relation and laterally expanding the slit and preformed strip. Concurrent slitting and preforming and subsequent slitting can be effected by a cluster of three rolls or by a linear arrangement of pairs of opposed rolls.The invention has particular utility in forming expanded mesh sheet of exact final dimensions for use as battery grids from lead or lead alloy strip.

Abstract: A cathode assembly for the electrodeposition of metals comprising in combination at least one edge stick engaging at least one edge of a cathode, wherein the cathode has at least one upstanding projection on each of its surfaces proximate said edge, the projections each having an upstanding face which is both substantially parallel to the proximate cathode edge and facing away therefrom, and wherein the non-conductive plastic edge stick is of channel-like form, the inner trough faces of the channel being adapted to engage securely with the projections proximate the cathode edge, thereby to retain the edge stick thereupon. This assemblage has the advantages of simplicity of construction and assembly, while also avoiding any weakening of the cathode edge.

Abstract: A method for the removal of moisture associated with sulfur and for the melting of solid sulfur. A flow of molten sulfur is circulated through a mixing device in a substantially spiral flow wherein the circulating molten sulfur forms a continuous vortex of molten sulfur. Particulate solid sulfur with or without associated moisture, either as such or in the form of an aqueous slurry or moisture-containing liquid sulfur is fed into the vortex of circulating molten sulfur. Sulfur is discharged from the mixing device and any associated moisture is evaporated and separates from the sulfur. Molten sulfur substantially free of moisture is recovered.

Abstract: In the electrodeposition of metals in electrowinning and electrorefining processes, the current between end electrodes in a cell is generally higher than the average current between all electrodes in the cell thereby causing warping of the end electrodes, overheating of the electrical contacts at the end electrodes and a majority of the electrical shorts to occur at these end electrodes. These problems are alleviated by controlling the current between the first two and between the last two electrodes at a value that is not greater than the average value of the current between all electrodes in the cell, by increasing the lateral spacing between the end electrodes and their immediate neighboring electrodes.

Abstract: A cutting apparatus for slicing semiconductor materials into wafers is disclosed.

Abstract: A process is described for the removal of chloride impurity from zinc sulphate solution. The process comprises the steps of forming a slurry of said solution with an inert particulate support material having elemental silver dispersed thereon, and an oxidizing agent, agitating said slurry at a temperature between about 60.degree. and about 100.degree. C. for precipitation of silver chloride on said support material, filtering said slurry to separate purified zinc sulphate solution from the support material containing the precipitated silver chloride, and treating said separated support material containing precipitated silver chloride with a reductant in an aqueous alkaline medium to regenerate elemental silver on said support material.

Abstract: A method is disclosed for removal of free and complex cyanides from water-containing industrial effluents and wastes by treatment with insoluble solid iron sulfides at a pH in the range of about 7.0 to 8.5. The insoluble solid iron sulfides can be chemically prepared prior to treatment or prepared in situ, usually of a particle size smaller than about 5.mu., or supplied in the form of naturally occurring iron sulfides such as pyrrhotite or pyrite having a particle size smaller than about 300.mu., preferably smaller than about 150.mu.. The weight ratio of iron sulfide to total cyanide in the effluent is greater than 2:1, preferably greater than about 5:1 for prepared iron sulfides and greater than about 100:1 for mineral sulfides. The presence of a reducing agent such as ferrous ions or sodium sulfite to maintain a non-oxidizing environment during treatment enhances removal of cyanide.

Abstract: A damper assembly for closure of a duct for conveying hot corrosive gases is disclosed.