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[4] [11] The leaching is typically described by solute transport models, such as Darcy's Law, mass flow expressions, and diffusion-dispersion understandings. [4] Leaching is controlled largely by the hydraulic conductivity of the soil, which is dependent on particle size and relative density that the soil has been consolidated to via stress. [4]
Leaching involves the use of aqueous solutions to extract metal from metal-bearing materials which are brought into contact with them. [3] In China in the 11th and 12th centuries, this technique was used to extract copper; this was used for much of the total copper production. [4]
The basic ore slurry can be combined with a solution of sodium cyanide or potassium cyanide; many operations use calcium cyanide, which is more cost effective. To prevent the creation of toxic hydrogen cyanide during processing, slaked lime ( calcium hydroxide ) or soda ( sodium hydroxide ) is added to the extracting solution to ensure that the ...
Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within the ore, into soluble salts while the impurity remains insoluble. These can then be washed out and processed to give the pure metal; the materials left over are commonly known as tailings .
Solvent extraction and electrowinning (SX/EW) is a two-stage hydrometallurgical process that first extracts and upgrades copper ions from low-grade leach solutions into a solvent containing a chemical that selectively reacts with and binds the copper in the solvent.
In electrowinning, an electrical current is passed from an inert anode through a leach solution containing the dissolved metal ions so that the metal is recovered as it is reduced and deposited in an electroplating process onto the cathode. In electrorefining, the anode consists of the impure metal (e.g., copper) to be refined. The impure ...
The process is often used to refine leach solutions. Cementation of copper is a common example. Copper ions in solution, often from an ore leaching process, are precipitated out of solution in the presence of solid iron. The iron oxidizes, and the copper ions are reduced through the transfer of electrons.
Pregnant leach solution or pregnant liquor solution (PLS) is acidic metal-laden water generated from stockpile leaching and heap leaching. Pregnant leach solution is used in the solvent extraction and electrowinning (SX/EW) process.