A complex ore can be considered a mineral trash pile. Complexity is usually determined by the amount of minerals contained in the metal. When mixed sulfides of iron, copper, selenium and tellurium are at high levels in the ore, it is considered a complex or refractory ore. For metals to be at their purest, the complex ores must be separated or "leached". Leaching is a method of extracting the desired metal by passing a solvent through the ore. While there are several methods of leaching ores, heap leaching has proved to be the most efficient and cost effective.
Things You'll Need
Water sprinkler system
Heap pad liner
Heap pond liner
Leaching solution
Granulated activated carbon
Caustic solution
Electrolytic cells or zinc dust precipitation vat
Metal melting furnace
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Instructions
Basic Steps
1
Ores must first be crushed into smaller chunks before leaching.
Crush the complex ore into small chunks.
2
Construct a heap pad with drainage pond. The heap pad is a significant part of the heap leaching process. The best design calls for the heap pad to be nearly flat, with no more than a 1 percent slope.
3
Place the liner on the heap pad.
4
Heap the crushed ore onto the liner.
5
Leaching solution washed through the ore releases precious metals.
Irrigate the heap with a leaching solution. Drip Emitters, wobbler or reciprocating sprinklers can be used for this purpose. This process can take several weeks.
6
A collection pond catches the leaching solution impregnated with precious metals.
Collect the irrigated solution in the heap "pond". The heap pond can be any type of collection vat; man made or natural.
7
Agitate the solution.
8
The leaching solution is filtered for solid metals, which are then melted down into bullion bars.
Filter the solid metal from the remaining solution. The majority of facilities filter the solid metal by adding granular activated carbon to the solution. The metal adheres to the carbon and the resulting carbon-metal particles are then removed from the solution. The metal is extracted from the carbon using a hot caustic solution. After passing through electrolytic cells or a zinc dust precipitation vat, the metal is melted to produce impure bullion bars.