Abstract: A composition and method for coating the surface of steel casting dies for molten metals are described. The composition comprises a dispersion of boron nitride powder, an elastomeric polymer and an organic solvent or diluent. The elastomeric polymer consists of two fractions, a high-polymer fraction and a low-polymer fraction. The treatment provides thermal insulation to the mold surface, thereby minimizing premature solidification of the cast metal.

Abstract: A weather-resistant TiO.sub.2 pigment having improved optical properties is provided. The pigment is substantially encapsulated with a coating of an amorphous, dense silica in an amount between about 1% and about 7%; a coating of a voluminous silica in an amount between about 1% and about 8%; and preferably a coating of a precipitated alumina in an amount between about 2% and about 8%. In a particularly preferred embodiment the pigment further includes an innermost coating of a precipitated alumina in an amount between about 0.2 and 0.6%, the percentages of silica and alumina being calculated as % SiO.sub.2 and Al.sub.2 O.sub.3 by weight, based on the final treated TiO.sub.2 pigment. A process for manufacturing the pigment is further provided.

Abstract: An electrolyte solution and the method of using same for electrodeposition of black chromium on a substrate, said solution comprising water, trivalent chromium ions, ions of a metal selected from the group consisting of iron and cobalt, a weak complexing agent for the trivalent chromium ions, and phosphate ions. The preferred complexing agents are hypophosphite or formate.

Abstract: A dispersion composition and a method for coating the surface of steel casting dies for molten metals are described. The dispersion composition comprises boron nitride powder dispersed in a peroxide-modified aqueous dispersion of a water-dispersible film-forming polymer. The coating composition provides thermal insulation to the mold surface, thereby minimizing premature solidification of the cast metal.

Abstract: A process for precipitating iron as a jarosite from a sulphate solution containing ferric iron, free acid and valuable non-ferrous metals, characterized by cooling the solution; partially neutralizing the free acidity, and then clarifying the solution; heating the clarified solution to a temperature not exceeding the boiling point at atmospheric pressure, in the presence of at least one ion selected from the group consisting of sodium, potassium and ammonium ions, and in the presence of recycled jarosite, and without the addition of any further neutralizing agent, so that substantially all of the ferric iron is precipitated as a jarosite; and separating precipitated jarosite from the solution; thereby producing a jarosite contaminated with only minor amounts of non-ferrous metals, and a solution which may be further processed by established procedures for the recovery of dissolved valuable non-ferrous metals therefrom. The invention also contemplates a dilution step, and recycle of jarosite.

Abstract: Newly isolated polysaccharide assimilating yeasts are added to a waste water rich in nutrients thereby making such yeasts assimilate nutrients, so that B.O.D. of the waste water is efficiently decreased. Among the polysaccharide assimilating yeasts, ellipsoideus YS-1, FERM-P No. 4498, in particular, can decompose and assimilate sulfurous acid, starch and protein at once, and therefore the B.O.D. of the waste water from starch production plants can be considerably decreased.

Abstract: In a process for recovering zinc from residues containing it, particularly rom ashes and hard-spelters coming from galvanizing baths, and which comprises the extraction by electrolysis of the zinc contained in the alkaline or acid solutions obtained. The solutions deriving from the ashes are obtained by dissolving their relatively low metallic zinc content granulometric fraction, the high metallic zinc content granulometric fraction of these ashes being re-introduced directly into the galvanizing bath advantageously after a leaching treatment and the solutions deriving from the hard-spelters are obtained by dissolving them either by having recourse to a corrosion cell or by forming by means of these hard-spelters the anodes of an electrolysis circuit.

Abstract: A method whereby a surface of chromium metal electrodeposited on a zinc substrate from a trivalent chromium electrolyte is treated by contacting the surface with an aqueous solution at a pH of from 5 to 12 and containing a dissolved metal salt of a weak acid which does not form a soluble complex with zinc. Preferred salts are carbonates, phosphates and silicates of an alkali metal, e.g. sodium or potassium. Also disclosed is the product of said process comprising an article having a zinc substrate, a microporous electrodeposited chromium coating from 0.025 to 2.5 microns in thickness on said substrate, and a water-insoluble basic salt of zinc within the micropores.

Abstract: An electrolyte bath and a method for using such a bath comprising trivalent chromium ions dissolved in an aqueous solution containing sulphide. The bath may also contain a weak complexing agent such as hypophosphite or glycine. The electrolyte according to the invention permits the electrodeposition of chormium from electrolytes having low solids content without adversely affecting plating rates.

Abstract: Process for removing chlorine from an acidic zinc or cadmium sulphate solon, comprising adding thereto acid of Caro or an ammonium or alkali metal salt thereof.

Abstract: Apparatus for polishing metal electrolytic refining cathode plates, in which cathode plates are transported individually by means of a series of transferring and hanging devices, with the cathode plates thus transferred being polished in a polishing mechanism while moved vertically and while their dielectric frame supporters are protected so as not to be subjected to the polishing operation effected by the polishing mechanism.

Abstract: The invention relates to a process for recovering silver and possibly gold contained in a silver and possibly gold bearing solid starting material, in which said metals are present in low proportions, a part thereof being in the form of free sulphides, possibly in mixture with elemental sulphur, in which said starting material is treated with an aqueous solution of thiourea, so as to solubilize the silver and the gold in the form of complexes with the thiourea, and the obtained solution is subjected to a cementation with a metal so as to obtain a cement containing more than about 90% of silver.

Abstract: A process for simultaneously preheating and preparing a ferrous surface, prior to the depositing thereon of galvanized zinc coatings, replaces conventional fluxing techniques with the step of immersing a ferrous object in a bath of a molten salt or salts. The salts are chosen so that they are liquid at a temperature below that of the zinc coating step. The liquid acts as a non-fuming flux and preheat for the surface. Particular salts include metallic hydroxides and halides.

Abstract: The properties of brass powder compacts are improved by including selected amounts of cobalt in the brass powder compositions; specifically brass powder compacts broadly comprising about 5% to about 45% zinc, about 1% to about 7% cobalt, balance essentially copper, are disclosed.

Abstract: A process for treatment of lead residues, without prior sintering, in which residues more than 70% of the lead is present as lead sulphates, comprising addition of the said residues, together with a reductant containing carbon and together with fluxes that will react to provide a slag containing FeO, CaO and SiO.sub.2, directly to an electric furnace operating at a temperature of 1000 to 1500.degree. C in the slag layer to produce in the furnace a lead bullion. The expression "lead sulphates" will be understood to include lead sulphate and other compounds containing lead and the sulphate ion, for example, the basic lead sulphates.

Abstract: A desulfurization process is provided using particulate zinc oxide shapes of high surface area and improved crushing strength prepared without extraneous binder by a process including forming normal surface area zinc oxide into shapes without binder, converting at least a portion of the zinc oxide to basic zinc carbonate by exposing the shapes in the presence of moisture, to a carbon dioxide-containing atmosphere and effecting substantially complete decomposition of the basic zinc carbonate. Conditions of bulk density, moisture content and temperature are controlled.

Abstract: Solution and procedure of depositing a coating on the surfaces of zinc-coated ferrous metal parts which protects against corrosion in the presence of water. The solution is made up by adding to water, perliter of final solution, of 1 to 40 grams of sodium metasilicate, 14 to 40 milliliters of phosphoric acid, specific gravity 1.71, from 1 to 40 grams of sodium nitrate, from 10 to 50 grams of anhydrous zinc chloride and the pH is adjusted to a value between 2.3 and 3.8. Preferably nickel chloride is added. For use, the solution is heated to a temperature ranging from 15.degree. to 75.degree. C and brought into contact with the parts to be treated for a period from 20 to 72 hours. The deposit is continuous, hard, resistant to shocks and abrasion and imparts an efficient and lasting protection to galvanized parts in corrosive waters. The invention is useful for the protection of piping in the building industry.

Abstract: Solution and procedure of depositing a coating on the surfaces of zinc-coated ferrous metal parts which protects against corrosion in the presence of water. The solution is made up by adding to water, per liter of final solution, of 1 to 40 grams of sodium metasilicate, 14 to 40 milliliters of phosphoric acid, density 1.71 g/ml, from 1 to 40 grams of sodium nitrate, from 10 to 50 grams of anhydrous zinc chloride and the pH is adjusted to a value between 2.3 and 3.8. Preferably nickel chloride is added. For use, the solution is heated to a temperature ranging from 15.degree. to 75.degree. C and brought into contact with the parts to be treated for a period from 20 to 72 hours. The deposit is continuous, hard, resistant to shocks and abrasion and imparts an efficient and lasting protection to galvanized parts in corrosive waters. The invention is useful for the protection of piping in the building industry.

Abstract: Solution and procedure for depositing a coating, comprising hydrated zinc pyrophosphate, on the surfaces of galvanized steel parts, to protect against corrosion in the presence of water. The aqueous solution contains, per liter of final solution, hexametaphosphate equivalent to 10 to 70 grams of sodium hexametaphosphate, metasilicate equivalent to 1 to 40 grams of sodium metasilicate, an amount of orthophosphoric acid equivalent to 15 to 40 milliliters of orthophosphoric acid having a density of 1.71 g/ml, zinc chloride in an amount equivalent to 10 to 50 grams of anhydrous zinc chloride, and calcium carbonate sufficient to bring the pH of the solution to between 2.0 and 3.0. Nickel, equivalent to 0.5 to 20 grams per liter of final solution of hexahydrated nickel chloride, and chlorate, equivalent to up to 20 grams of sodium chlorate per liter, may be added. The solution is used by contacting it with the parts to be treated for a time determined on the one hand by the solution temperature (between 10.degree.

Abstract: An aqueous trivalent chromium plating bath having low temperature stability comprising trivalent chromium ions preferably in a concentration of at least 0.2 M, sulphate ions preferably in a concentration of at least 0.3 M, a weak complexing agent for the chromium ions in a concentration of at least 0.1 M, and fluoride ions in a concentration of at least 0.025 M. The bath preferably also contains chloride ions in a concentration of at least 0.1 M.