Effect Particle Size on Leaching of Sulphide Minerals
Commercial leaching of sulphide ores by microorganisms is used in numerous oxidation situations as a scavenger process for treating low grade ores and very dilute metal waste streams at comparatively low capital and operating costs compared with conventional hydrometallurgical processes. Studies using synthetic mixtures to give pre-determined surface areas have also revealed that the size […]
Gold & Uranium Pregnant Solution Clarification
Before precipitation of gold can be commenced the relatively high suspended solids content (on average 350 mg/L) of the gold bearing rotary filtrate has to be reduced below 5 mg/L. On most gold mines to which AAC provides technical services a final polishing step to achieve the required clarity takes place in Stellar pre-coat candle […]
Gold & Silver Leaching Methods
Climbing gold and silver prices during the 1970’s awakened dormant interest in mining these metals in many districts. Since gold and silver deposits frequently can be profitably mined by small operators, a mix of mining activity has been created, comprised of large and small companies, both experienced and unexperienced. A key factor in the profitability […]
Aluminum Extraction Method with Chloride
Almost all aluminum in the United States is produced from imported bauxite or alumina. This country has, however, more than adequate domestic nonbauxitic alumina resources that could alleviate dependency on foreign sources. For both economic and security reasons, the Federal Government has had a longstanding interest in the development of alternative technology that would allow […]
How to Dissolve Galena
There has been growing concern about the adverse effects on the environment associated with high temperature processing of galena. Because of the difficulties encountered with conventional smelting, the use of hydrometallurgical techniques for lead processing has received considerable attention in the past few years. With hydrometallurgical processing, sulfur dioxide is not produced and lead-bearing particles […]
Copper Concentrate Enrichment Process
Most copper ore currently being mined contains copper mainly as chalcopyrite. Since chalcopyrite by itself is only about 35 percent copper, it is difficult to upgrade a concentrate by flotation to more than about 25 to 28 percent copper without losing a significant amount of copper during the cleaning steps. Some ores have associated problems […]
Preventing Chromium Leaching
This report presents the results of research aimed at evaluating and preventing the leaching action that may result from the disposal of waste ferrous slags into landfills where they can be subjected to acid precipitation. Waste slag constitutes a large potential source of chromium contamination of ground waters, particularly under the enhanced leaching action of […]
Ilmenite Chlorination
To help assure an adequate supply of raw materials to meet national economic and strategic needs, the Bureau of Mines undertook research to devise technology to efficiently and economically recover titanium from low-grade domestic deposits. The objective of this research was to devise a means for producing chlorination-grade feedstock from low-grade ilmenlte rock concentrate made […]
Chloride Leaching Sulfide Concentrates
The fact that chloride oxidates can solubilize base metals from sulfide concentrates has been known since the 1880’s. The work of Hoepfner in 1902 was particularly accurate for its time with regard to the chemistry of chloride solutions. Recent work has dealt with the understanding of chloride extraction thermodynamics by modelling the behavior of metal […]
Converting Chalcopyrite to Copper Sulfides
This is of special interest in hydrometallurgical processing since it provides an upgraded sulfide and rejects iron to solution. Also, the conversion of chalcopyrite is an important process in secondary mineralization during supergene enrichment, and secondary mineralization may occur during long cycles of dump leaching. In deep solution mining, secondary reactions undoubtedly will assume an […]