Abstract: A process for the modification to existing and conventional reverberatory furnaces for smelting copper concentrates in such furnaces, for improving the thermal efficiency of the furnace and for achieving an increased concentration of SO.sub.2 in the gas emanating from the furnaces, by the use of specially designed lancing assembly.

Abstract: Gold-bearing ore of sedimentary origin containing organic carbonaceous material and gold-bearing sulfides is treated to increase the recovery of the gold content thereof by standard cyanidation practice. An aqueous slurry of the finely ground ore is first subjected to a preliminary oxidation treatment wherein air or oxygen is bubbled through the slurry while maintaining the slurry at a temperature of from 167.degree. to 212.degree. F. for a period of from 8 to 24 hours. The oxygenated slurry is then cooled to a temperature of from 70.degree. to 125.degree. F. and acid is added to bring the pH of the slurry down to 6.0 of lower. Chlorine gas or an alkali metal or alkaline earth metal hypochlorite is then added to the slurry unitl the slurry will no longer absorb or react with these reagents. The thus treated slurry is maintained at a temperature of from 70.degree. to 125.degree. F. for a period of from 6 to 12 hours.

Abstract: When certain sedimentary gold ores containing indigenous organic carbonaceous materials are slurried with an aqueous solution containing an alkali metal cyanide, the aurocyanide complex which is formed is adsorbed by an adsorptive carbon component of the ore. Dissolution of the gold proceeds until chemical equilibrium is attained between the aurocyanide complex in solution and the aurocyanide complex adsorbed by the ore. In the process of the invention, the gold is dissolved from the ore by using (1) much higher strengths of cyanide solution, and (2) much higher temperatures than are normally used in the standard cyanidation process, allowing higher extractions of gold to take place. Because the concentration of aurocyanide in solution is limited by chemical equilibrium, the dissolution of gold must be done in stages.

Abstract: A process for the treatment of zinc calcine containing zinc oxides, zinc sulfates and zinc ferrites, which comprises neutral leaching, hot acid leaching, jarosite precipitation and recycling of the jarosite containing pulp whereby there is obtained increased zinc extractions, improved settling and filtering characteristics of the leach pulp, simplified operation and process control and increased ammonium removal.

Abstract: The gold, silver and selenium content of copper refinery slimes are recovered by first leaching the slimes with dilute sulfuric acid at an elevated temperature and at a partial pressure of oxygen of between about 5 and 50 psig. to obtain a leach solution containing at least about 98% of the copper content of the raw slimes. The decopperized leach residue is dried and then roasted in an oxidizing atmosphere at a temperature of about 400.degree. to 800.degree. C. to obtain effluent roaster gases containing substantially all of the selenium content of the raw slimes in the form of selenium dioxide, the effluent roaster gases being treated to recover the selenium dioxide content thereof. The deselenized roaster residue is mixed with dilute acid and ferric chloride to form a slurry through which chlorine gas and air are continuously bubbled for a period of at least about 5 hrs. to obtain an extraction liquor containing the gold content and a chlorination residue containing the silver content of the raw slimes.

Abstract: A process for the preferential removal of soluble manganous ions from a metal bearing solution, particularly a zinc sulfate solution to be subjected to electrolysis for the recovery of zinc, comprising treating said solution with an oxidant capable of oxidizing soluble manganous ion to insoluble and filterable gamma-manganese dioxide at a temperature and for a time sufficient to precipitate at least a portion of the manganese present in said solution as gamma-manganese dioxide, said oxidant being in an amount of from about 130% to 150% of the theoretical amount required for substantially total manganese removal from said solution, and separating said precipitate from said solution.

Abstract: The recoverability by cyanidation of the gold content of sedimentary gold-bearing ores containing organic carbonaceous material and gold-bearing pyrite, or other gold-bearing sulfides, is greatly increased by heating an aqueous slurry of the ore to about 167.degree. to 212.degree. F. and then introducing air or oxygen into the heated slurry to oxidize and eliminate a substantial portion of the carbonaceous material and oxidizable sulfides in the slurried ore, followed by cooling the slurry to about 70.degree. to 85.degree. F. and then introducing chlorine gas into the slurry to substantially complete the oxidation and chlorination of the carbonaceous content of the slurried ore. The ore is then subjected to conventional cyanidation to recover the gold content thereof.