Abstract: A method for selectively dissolving non-ferrous metals contained in pyritic ores by the steps of crushing the ores, introducing the crushed ore at a temperature above the ambient temperature into a reaction vessel containing a solution of chlorides of a metal having two valance states, and injecting gaseous chlorine into the reaction vessel at a rate such that the oxido-reduction potential of the solution of chlorides remains between 400 and 700 mv during the operation.

Abstract: A quantitative hydrometallurgical process for the selective conversion of lead sulfide (galena) to its sulfate form under ambient conditions of temperature and pressure. The process works in the presence of associated zinc - copper - iron sulfides which survive the process in a relatively unaltered condition. It is directly applicable to ores or derived concentrates of complex sulfide systems. The lead sulfate is isolated from the ore or concentrate system by a brine wash with subsequent conversion to lead chloride. A free concentration of cupric ion is maintained during the leaching stages to act as an oxidation catalyst and to inhibit the dissolution of zinc sulfide. The forward reaction in terms of lead sulfation is controlled by a chlorite-type mineral with both anion and cation exchange capacity added to, or maintained in a dilute sulfuric acid leach cycle.

Abstract: A hydrometallurgical process for treating iron containing metal sulfides for rendering iron and non-ferrous metal values active and amenable for selective extraction and separate recovery. Sulfur values can be controllably produced as elemental sulfur or as sulfuric acid to supply acid requirements of the process, while substantially obviating the discharge of sulfur-containing gases to the atmosphere. Ores and concentrates of the sulfides are thermally activated by sequentially heating and reducing said sulfides in a countercurrent flow of heating and reducing gases respectively in a reactor whereby the reaction products of the reducing gas and sulfides, together with liberated labile sulfur, are controllably combusted with oxygen to satisfy heat requirements of the thermal activation process and to convert sulfur values to SO.sub.2 gas. The activated sulfides are subjected to an acid leach in aqueous sulfuric acid for production of ferrous sulfate and evolution of H.sub.

Abstract: Fine crystalline powder, from 0.02 to 0.2 micron in average particle size, of a composition Pb(Zr.Ti)O.sub.3. Parts of Zr and Ti of the composition may be substituted for with Mn and Sb, Nb, and/or Ta. The powder is produced by preparing an acidic aqueous solution of the constituent metallic ions, neutralizing the solution to provide a suspension of hydroxides of the metals, and subjecting the suspension to hydrothermal reaction at 150.degree.-300.degree.C. The powder provides piezoelectric ceramics of a high sintered density without resorting to hot pressing.

Abstract: A process for producing metallic lead and silver from materials such as ores and concentrates containing the corresponding sulfides and particularly a mixture of minerals such as galena and tetrahedrite in which process the minerals are initially roasted under neutral conditions which include a non-oxidizing or even slightly reducing atmosphere at an elevated temperature for a time equivalent to about 1.5 hours at about 550.degree.-600.degree.C. to produce a roasted mineral product in which the roasting causes certain unidentified changes but with the resulting roasted product being more easily leachable so that the process of removing the silver and lead can be greatly simplified.

Abstract: An improvement in the process of leaching metal sulfide minerals with an oxidative leaching solution is obtained by adding to the leaching solution over only a portion of the leaching cycle aqueous hydrogen peroxide in an amount ranging from about 2 to about 25 percent by weight of the quantity of hydrogen peroxide required to bring the metal value of the mineral into solution if hydrogen peroxide were used as the sole oxidizing agent.

Abstract: A method is disclosed for leaching finely divided lead sulphide bearing material to convert contained lead values to soluble lead acetate with concurrent conversion of sulphur values associated with the lead sulphide to an elemental state. The method involves forming a slurry consisting of the material dispersed in an aqueous medium containing free acetate ions and having a pH below 5.1. The slurry is reacted at a temperature of 60.degree. to 120.degree.C. with a free oxygen-bearing gas under a partial pressure of oxygen of 20 to 60 p.s.i. in order to convert lead sulphide to soluble lead acetate with concurrent production of insoluble elemental sulphur.