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Author: Admin | 2025-04-27
Preparation: The ore is finely ground and combined with sulfuric acid.Leaching: The mixture is heated in autoclaves at 245°C to 270°C under high pressure, which causes the nickel and cobalt to dissolve.Neutralization: The acidic leach solution is neutralized, causing iron and aluminum to precipitate as hematite and alunite/jarosite phases, which are then removed.Solvent Extraction (SX): Nickel and cobalt are separated from the solution using solvent extraction.Ammonia LeachingAmmonia leaching is another effective method, especially for nickel laterites. The steps are:Ore Preparation: The ore is crushed and ground into fine particles.Leaching: The ground ore is mixed with an ammonia solution, which forms soluble complexes with nickel and cobalt.Precipitation: Nickel and cobalt are extracted from the solution using hydrogen gas or other chemicals.Pressure Leaching and Hydrogen ReductionPressure leaching, or High-Pressure Acid Leaching (HPAL), is an advanced method for extracting nickel from lateritic ores. It involves:High-Pressure Acid Leaching (HPAL): The ore is treated in autoclaves with sulfuric acid at 245°C to 270°C under high pressure, dissolving nickel and cobalt into the solution.Hydrogen Reduction: Hydrogen gas is added to the solution after leaching to produce high-purity nickel.Atmospheric Acid Leaching (AAL)Atmospheric Acid Leaching (AAL) is an alternative to HPAL, performed at atmospheric pressure and lower temperatures (around 90°C). It is suitable for low-grade lateritic ores and involves:Sulfuric Acid Leaching: The ore is mixed with sulfuric acid in stirred tanks, which allows nickel to dissolve at lower costs than HPAL.Enhanced Extraction: Adding reagents like calcium fluoride can improve nickel extraction efficiency.Caron ProcessThe Caron process, mainly for limonitic ores, involves pyrometallurgical and hydrometallurgical steps:Drying and Reduction: The ore is dried and reduced at around 700°C to convert nickel to a metallic form.Ammoniacal Leaching: The reduced ore is leached in an ammonia solution to extract nickel and cobalt.Biochemical Leaching (BL)Biochemical Leaching uses microorganisms to extract nickel from ores. Although less common, this method involves:Microbial Action: Specific bacteria oxidize and dissolve nickel from the ore.Environmental Benefits: This environmentally friendly process is less efficient in selectivity and recovery rates compared to other methods.Heap LeachingHeap leaching, suitable for low-grade nickel ores, involves:Ore Stacking: The ore is stacked in heaps and irrigated with
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