Leaching heap method

Saltpeter may also be obtained from specially constructed "heaps of nitrous earth from which it is leached with w. This method is still in use in India (Ref 1, p 57)... 

Hydrometallurgical methods are normally employed for recovery of gold from oxidized deposits (heap leach), low-grade sulphide ores (cyanidation, CIP, CIL) and refractory gold ores (autoclave, biological decomposition followed by cyanidation). 

The most important copper electrowinning production method is heap leaching of oxide copper ores with recovery by solvent extraction and electrowinning (SX-EW process). The general flowsheet of an SX-EW process is shown in Fig. 18. It is a low-cost method of copper recovery. This technology has recently been applied successfully to mixed oxide and chalcocite ores, notably in Chile. Currently, there are significant development efforts underway to try to extend heap leaching to chalcopy-rite ores. 

Hydrometallurgical methods use reactions in aqueous solution (often involving metal complex formation) to concentrate and/or separate the metal ions of interest. A commercially important example is the heap leaching of low-grade copper ores with acid. 

The mining method selected for use is large scale open pit mining. The crushed (80% < 8mm) ore is agglomerated and conveyed to the heap pad. After 13 to 14 months of bioleaching on the primary pad, the leached ore is reclaimed, conveyed and re-stacked onto the secondary heap pad. After secondary leaching, the barren ore will remain permanently in the secondary heaps. In the... 

In unsteady-state leaching a common method used in the mineral industries is in-place leaching, where the solvent is allowed to percolate through the actual ore body. In other cases the leach liquor is pumped over a pile of crushed ore and collected at the ground level as it drains from the heap. Copper is leached by sulfuric acid solutions from sulfide ores in this manner. 

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