Agglomeration heap leaching of precious metals

CIM Bulletin, Vol. 80, No. 902, 1987

J.A. EISELE and D.L POOL, Reno Research Center, Bureau of Mines, U.S. Department of the Interior Reno, Nevada

The Bureau of Mines has developed a particle agglomeration technique to improve the flow of leaching solution through heaps of low-grade gold-silver ores which contain clays. Bench-scale experiments and industrial practice have shown that the percolation rate of cyanide leaching solution is greatly enhanced by mixing the ore with Portland cement as a binder, moistening the mixture, mechanically tumbling to form agglomerates, and aging before heap building and leaching. A slight modification of the technique allows its application to precious-metal-bearing tailings, which cannot normally be treated by heap leaching because they are too fine.
Keywords: Metallurgy, Agglomeration, Heap leaching, Cyanide leaching solution, Tailings, Precious metals, Gold, Silver.