leaching
Quick Summary
Leaching is a process in extractive metallurgy where metallic compounds are selectively dissolved from an ore using an aqueous solvent. This is a key step in hydrometallurgy, a branch of metallurgy focused on extracting metals using aqueous solutions.12
How Leaching Works
Leaching can be performed using various solvents depending on the metallic compound, such as sulfuric acid for oxides, water for sulfates, or cyanide solutions for precious metals. The process can occur at ambient temperature and pressure or under increased pressure and temperature to speed up dissolution. Different methods exist, including:1
- In situ leaching: Used for ores too deep for surface treatment, where a solution is circulated underground to dissolve metals.1
- Heap leaching: Ore is piled into heaps, and a leach solution is sprayed over it, dissolving values as it trickles down.1
- Tank leaching: Higher-grade ores are treated in large tanks, either in bulk or by agitating finely ground ore.1
The goal is to extract valuable metals from their complex chemical compounds, often converting them into more soluble forms before leaching. After leaching, the dissolved metals are recovered through processes like electrowinning or chemical precipitation.23
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chromium processingChromium metal…containing sodium chromate, which is leached from the insoluble gangue and then reduced and precipitated as Cr2O3. The Cr2O3 is blended with finely divided aluminum powder, charged to a refractory-lined container, and ignited. The combustion quickly generates temperatures in excess of 2,000 °C (3,600 °F), giving a clean separation of…
Read More…containing sodium chromate, which is leached from the insoluble gangue and then reduced and precipitated as Cr2O3. The Cr2O3 is blended with finely divided aluminum powder, charged to a refractory-lined container, and ignited. The combustion quickly generates temperatures in excess of 2,000 °C (3,600 °F), giving a clean separation of…
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copper processingLeachingOccasionally adopted in preference to smelting (or pyrometallurgy, as it is generally known), leaching, or hydrometallurgy, is carried out at lower temperatures and thus eliminates the generation of sulfur dioxide; there are, however, effluents and residues that must be treated in order to protect…
Read MoreOccasionally adopted in preference to smelting (or pyrometallurgy, as it is generally known), leaching, or hydrometallurgy, is carried out at lower temperatures and thus eliminates the generation of sulfur dioxide; there are, however, effluents and residues that must be treated in order to protect…
Read More- industrial glassChemical properties
The alkali ions thus leached out of the glass further react with carbon dioxide and water in the atmosphere to produce alkali carbonates and bicarbonates. These are seen as the white deposits that form on a glassy surface in dishwashing tests or after extended humidity exposure (often called weathering).…
Read MoreThe alkali ions thus leached out of the glass further react with carbon dioxide and water in the atmosphere to produce alkali carbonates and bicarbonates. These are seen as the white deposits that form on a glassy surface in dishwashing tests or after extended humidity exposure (often called weathering).…
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nickel processingFrom sulfide ores…process is the ammonia pressure leach, in which nickel is recovered from solution using hydrogen reduction, and the sulfur is recovered as ammonium sulfate for use as fertilizer. In another, the matte may be roasted to produce high-grade nickel oxides; these are subjected to a pressure leach, and the solution…
Read More…process is the ammonia pressure leach, in which nickel is recovered from solution using hydrogen reduction, and the sulfur is recovered as ammonium sulfate for use as fertilizer. In another, the matte may be roasted to produce high-grade nickel oxides; these are subjected to a pressure leach, and the solution…
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uranium processingRoasting…that may interfere in subsequent leaching operations.
Read More…that may interfere in subsequent leaching operations.
Read More- vanadium processingVanadium pentoxide
…a coproduct with uranium by leaching the ore concentrate for 24 hours with hot sulfuric acid and an oxidant such as sodium chlorate. After removal of solids, the leachate is fed into a solvent extraction circuit where the uranium is extracted in an organic solvent consisting of 2.5-percent-amine–2.5-percent-isodecanol–95-percent-kerosene. Vanadium remains…
Read More…a coproduct with uranium by leaching the ore concentrate for 24 hours with hot sulfuric acid and an oxidant such as sodium chlorate. After removal of solids, the leachate is fed into a solvent extraction circuit where the uranium is extracted in an organic solvent consisting of 2.5-percent-amine–2.5-percent-isodecanol–95-percent-kerosene. Vanadium remains…
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