Gold Sulphide Ore Oxidation by Alkaline Pressure
The U.S. Bureau of Mines developed an alkaline oxidative pretreatment to increase the recovery of gold from refractory sulfide ores containing arsenopyrite (FeAsS) and/or pyrite (FeS2). Pretreatment of a low grade ore containing 0.4% FeAsS, 3.5% FeS2, and 2.74g/mt Au with 1.2M NaOH, 40 psig 02, 100° C, and 4 hr in a 2-L autoclave […]
Leaching Supergene Copper Ore – Atacamite & Chrysocolla
The US Bureau of Mines is conducting core leaching experiments with sulfuric acid on oxide copper ores from the Cyprus Casa Grande and Asarco-Freeport Santa Cruz deposit in Arizona to further the understanding of the leaching process in supergene copper ores as it relates to in situ mining. Leach solutions from atacamite mineralization contained 5 […]
Column Leach Test Procedure & Variables
A hydrometallurgical testing program to define the basic criteria, like recovery and sulfuric acid consumption, for a commercial heap leach system design, to process the oxide Copper (Chrysocola). Leach parameters such as, amount of sulfuric acid in the cure solution, cure technique, particle size of the material, leach solution’s flowrate application, leach solution’s acid strength […]
Heap Leach – Ore Permeability Testing Method
The test method developed to determine the permeability of ore under increased confining pressure was modified from the Bureau of Reclamation test standard, Designation E-14 (Bureau of Reclamation, 1974). The test apparatus consists of a 12 inch diameter steel cylinder, bottom porous stone, base plate with a drain, porous top plate, reaction frame, and a […]
Laboratory Leaching Test Procedure
Laboratory Leaching tests of mine wastes are typically performed using procedures that fall into two basic categories: batch and continuous. These categories are analogous to batch and continuous reactor methods used in metallurgical processing. Batch reactors for leaching tests can be in the form of a closed vessel, a cell, or a column. A continuous […]
Remove Mercury during Gold Leaching
The gold ores that are currently being processed contain mercury which is not only hazardous to the environment, but also causes serious occupational health and economic problems during gold processing. Some of the mercury present in the ore is dissolved during cyanidation of gold. As the separation of mercury cyanide from gold cyanide is difficult, […]
Copper Solvent Extraction Pulsed Column
Pulsed columns, like other pulsed columns, consist of an active column section with decanters on either end. Test columns are usually in the 40 mm to 150 mm diameter range and the decanters are typically twice the diameter of the column. Commercial columns can be up to 3 m in diameter with 6 meter diameter […]
Chalcopyrite Chlorination Process for Copper Extraction
Interests in the hydrometallurgical processing of primary sulfide concentrates have revived because leaching in chloride media is rapid and is capable of recovering sulfur in elemental form, and also because rapid advances are being made in corrosion-resistant materials. A process is proposed which consists of low-temperature chlorination and selective oxidation of chalcopyrite concentrates to produce […]
Leaching Pyrite Gold Ore without Cyanide
Alternative reagents for gold leaching include thiocyanate (SCN-) and thiourea (SC(NH2)2). They are considered less toxic and more environmentally acceptable when compared to cyanide. One of the important features of thiocyanate and thiourea dissolution of gold is that the leaching can be performed in acidic media, enabling the use of soluble oxidizing agents, such as […]
Carbonaceous Gold Ore Mineralogy
Mineralogy and Occurrence of Gold: The term “carbonaceous” has been loosely applied to ore constituents of widely varying characteristics. Laboratory investigations by A. S. Radtke and B, J. Scheiner (1970) of the U. S. Geological Survey and the U. S. Bureau of Mines on carbonaceous ores from Carlin showed that they contained: (1) an activated carbon […]