Mining  Mining Techniques  In-situ leach

In-situ leach

In-situ leaching (ISL), also known as in-situ recovery (ISR) or solution mining, is a method of recovering minerals like copper and uranium throughout boreholes drilled into the deposit. The process primarily involves drilling of holes into the ore deposit. Explosive or hydraulic fracturing may be used to create open pathways in the deposit for solution to penetrate. Leaching solution is pumped into the deposit where it makes contact with the ore. The solution bearing the liquefied ore content is then pumped to the layer and processed. This process permits the extraction of metals and salts from an ore body without the requirement for conventional mining entailing drill-and-blast, open-cut or underground mining.

Method of In-situ leach mining

In-situ leach mining entails pumping of a leachate solution into the ore body via a borehole, which circulates via the porous rock dissolving the ore and is extracted by means of a second borehole.

The leachate solution differs according to the ore deposit - for salt deposits the leachate may be fresh water into which salts may willingly dissolve. For copper, acids are generally required to improve solubility of the ore minerals within the solution. For uranium ores, the leachate might be acid or sodium bicarbonate.

Soluble salts

In-situ leach is broadly used to extract deposits of water-soluble salts like sylvite (potash), halite (rock salt, sodium chloride), and sodium sulfate. It has been used in the US state of Colorado to take out nahcolite (sodium bicarbonate). In-situ leaching is frequently used when the sediments are too profound, or the beds too thin for predictable underground mining.