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Dump leaching is an industrial process to extract precious metals and copper from ores. [1]Dump leaching is similar to heap leaching, however in the case of dump leaching ore is taken directly from the mine and stacked on the leach pad without crushing where, in the case of gold and silver, the dump is irrigated with a dilute cyanide solution that percolates through the ore to dissolve gold ...
In 2011 leaching, both heap leaching and in-situ leaching, produced 3.4 million metric tons of copper, 22 percent of world production. [8] The largest copper heap leach operations are in Chile, Peru, and the southwestern United States. Although heap leaching is a low cost-process, it normally has recovery rates of 60-70%.
The heap design usually incorporates collection sumps, which allow the "pregnant" leach solution (i.e. solution with dissolved valuable metals) to be pumped for further processing. An example is gold cyanidation , where pulverized ores are extracted with a solution of sodium cyanide , which, in the presence of air, dissolves the gold, leaving ...
The extraction is conducted by dump leaching or heap leaching processes. Sodium cyanide is produced on a billion-ton/year scale mainly for this purpose. "Black cyanide", a carbon-contaminated form of calcium cyanide (Ca(CN) 2) is often used because it is cheap. The crude ore is washed with a c. 0.3% solution of cyanide in air, often repeatedly ...
Drawbacks of leaching include its lower efficiency and the often significant quantities of waste effluent and tailings produced, which are usually either highly acidic or alkali as well as toxic (e.g. bauxite tailings). There are four types of leaching: [not verified in body] Cyanide leaching (e.g. gold ore) Ammonia leaching (e.g. crushed ore)
Heap bioleaching is a newer take on dump leaching. [16] The process includes more processing in which the rocks are ground into a finer grain size. [16] This finer grain is then stacked only 2 – 10 m high and is well irrigated allowing for plenty of oxygen and carbon dioxide to reach the bacteria. [16]
The company had said in a regulatory filing on Wednesday that operations were suspended as a result of a "large slip on the heap leach pad". ($1 = 1.3484 Canadian dollars)
In some cases, sulfide ores are allowed to degrade to oxides. Such ores are amenable to hydrometallurgy. Specifically, such oxide ores are usually extracted into aqueous sulfuric acid, usually in a heap leaching or dump leaching. The resulting pregnant leach solution is purified by solvent extraction (SX).