Abstract: The invention concerns a method for making a micaceous product capable of being impregnated preferably in the form of a mica ribbon by combining at least a support and a mica sheet. The invention is characterized in that it consists in: coating the support and the sheet with a solvent-fee resin or a mixture of solvent-free resins using several coating rollers brought to a temperature for producing the coat; combining the support with the mica sheet; subjecting them to a pressure and heat treatment.

Abstract: The anodes for the electrolytic production of zinc from acid aqueous solutions of sulphate comprise a skin portion formed by conventional anode metal, lead containing from 0.25 to 1.0% silver, and a stiffening reinforcing member of titanium or zirconium. The reduction in thickness of the anodes, which is made possible by the provision of the reinforcing member, results in a substantial saving in the amount of silver-bearing lead which is immobilized, and a substantial reduction in the unit weight of the anodes. The resistance of the lead to anodic corrosion in a sulphuric acid medium is maintained and the resistance to corrosion by passivation of the reinforcing member permits the reinforcing member to be accidentally exposed, without disadvantage. To produce the anodes, the reinforcing members are clad with lead at a temperature of more than 100.degree. by rolling sheets of lead, by casting in a mould or by spraying on molten lead.

Abstract: A method and apparatus for electrolytically preparing in an electrolytic cell metal, preferably zinc, in pulverulent form from a compound of the metal, for example, zinc oxide, in an aqueous ionized solution, for example potassium hydroxide of a concentration of 100 to 800 g/l, the solution preferably containing 10 to 350 of zinc per liter. The cathode at the bottom of the electrolytic cell comprises a layer of the same pulverulent metal, for example zinc, into which a grid cathode current input is introduced, the cathode current applied being sufficient to prevent the formation of metal in continuous form, preferably between 8 and 18 A/dm.sup.2. The anode is disposed in the cell above the cathode. New solution is injected about the lower periphery of the cell so as to set the solution and pulverulent metal is turbulent suspension.

Abstract: Process for the recovery of pigment-grade iron oxide and technical hydrochloric acid of predetermined molarity, from iron chloride solutions such as pickling solutions containing hydrochloric acid. The iron chloride solution is concentrated until the molarity of the chloride ion therein is the same as the molarity of the hydrochloric acid which it is desired to produce. Concentrated sulfuric acid in slight stoichiometric excess relative to the iron, is then added to the iron chloride solution, which solution is thereafter evaporated to dryness. The distillation from this evaporation is hydrochloric acid of the predetermined molarity, and the dry residue is iron sulfate. The iron sulfate is calcined to drive off sulfur dioxide and sulfur trioxide and to leave iron oxide which may contain sulfates; and to remove these latter, the iron oxide is leached with dilute hydrochloric acid and is thereafter washed with water. The washed iron oxide is dried and micropulverized to produce a red iron oxide pigment.

Abstract: In a process for the recovery of metal chlorides from jarosite in sludges which result from the sulphuric acid processing of ores, the sludge is treated with an aqueous solution of an alkaline earth metal chloride. This solution contains free hydrochloric acid and is in excess stoichiometric ratio to the sulphate content of the sludge. The insoluble materials are separated from the metallic chloride solution by filtering, and are stripped of metallic chlorides by washing and further filtering. The metallic chloride solutions are then collected. The alkaline earth chloride is preferably calcium chloride. The process is particularly, but not exclusively, applicable to recovering metals from jarosite-type sludge resulting from the processing of zinc ore.

Abstract: A process of leaching silicated zinc ores with sulfuric acid in which the ore is reacted at elevated temperature with at least a stoichiometric amount of sulfuric acid, treating products of the reaction with a predetermined quantity of hot water, filtering the zinc sulfate solution from precipitated silica, washing with a further predetermined quantity of hot water (the total amount of hot water used being determined so as to obtain the desired concentration of zinc in solution). The zinc is later recovered electrolytically. A 1 to 6N sulfuric acid solution may be used in which case a gelatinous mass is formed upon reaction and then it is evaporated at 100.degree. C of at least 60% of its water content. Alternatively the ore can be malaxated with about 20% stoichiometric excess concentrated sulfuric acid, and filtered at out at elevated temperature.

Abstract: A method and apparatus for electrolytically preparing in an electrolytic cell metal, preferably zinc, in pulverulent form from a compound of the metal, for example, zinc oxide, in an aqueous ionized solution, for example potassium hydroxide of a concentration of 100 to 800 g/l, the solution preferably containing 10 to 350 of zinc per liter. The cathode at the bottom of the electrolytic cell comprises a layer of the same pulverulent metal, for example zinc, into which a grid cathode current input is introduced, the cathode current applied being sufficient to prevent the formation of metal in continuous form, preferably between 8 and 18 A/dm.sup.2. The anode is disposed in the cell above the cathode. New solution is injected about the lower periphery of the cell so as to set the solution and pulverulent metal is turbulent suspension.

Abstract: A process for the re-utilization of the sulphate residues from the electrolytic treatment of zinc.The residues are digested hot with concentrated HCl in the presence of CaCl.sub.2. PbCl.sub.2 crystallizes on cooling. FeCl.sub.3 is extracted with TBP circulating in the direction of a series of columns and FeCl.sub.3 is extracted in a first column, washed in a second column and re-extracted a third column. The solution which issues is treated with NH.sub.3, resulting in precipitation of the majority of the hydroxides of the metals contained therein, which are subsequently separated, while Ag, Zn and Cu are complexed. Ag is precipitated with (NH.sub.4).sub.2 S.NH.sub.3 is recovered by means of lime. CaCl.sub.2 is re-cycled to the start of the process and Cu and Zn are leached together with the mineral.Application of the process to the recovery of the metals contained in the residues from the digestion of blends.

Abstract: Method for recovering potassium hydroxide and zinc oxide from potassium zincate solutions, characterized in that a selective solvent of potassium hydroxide, which is miscible with water, is added to the zincate solution, in that the zinc oxide precipitate thus obtained is filtered and in that the mother liquors for separating the potassium hydroxide solution from the solvent are treated. The invention applies to all electrochemical storage cell batteries having a zinc negative electrode in which it is required to purify the electrolyte with a view to scavenging it.