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Click to add WeChatGold mines have high mining value, and their beneficiation processes are relatively complex, and the beneficiation methods are even different. At present, the common gold ore beneficiation methods mainly include: cyanide method, flotation method and gravity separation method. Next, let’s learn about these gold ore beneficiation methods!
The cyanide gold extraction process is mainly divided into two categories: stirring cyanide gold extraction and percolation cyanide gold extraction. Among them, stirring Cyanidation is mainly used to treat flotation gold concentrate or all-sludge cyanidation operations; while percolation cyanidation is mainly used to treat low-grade gold-containing oxidized ores.
The gold extraction method by stirring cyanide can also be divided into two types, one is the cyanide-zinc replacement method (CCD method and CCF method), which requires continuous countercurrent washing and replacement of precipitation with zinc powder (silk) to recover gold; the other is the carbon slurry method (CIP method and CIL method), which does not require filtration and washing, and directly uses activated carbon to adsorb and recover the cyanide slurry. gold.
1. Cyanide-zinc replacement gold extraction method
It is mainly used to treat gold-containing precious liquid after cyanide leaching. The principle is to use zinc powder ( Silk) is used as a reducing agent to replace gold and silver from the leachate, including countercurrent washing solid-liquid separation, leachate purification, deoxidation, and zinc powder replacement operations.
Countercurrent washing solid-liquid separation:Separate the cyanidated precious liquid from the solid.
Leachate purification: Remove suspended solids in the precious liquid (leaching liquid), so that the gold-containing precious liquid entering the replacement operation reaches a clear and transparent state.
Deoxygenation: Remove dissolved oxygen in your solution.
Zinc powder replacement:Use zinc powder to replace the precious metals in the precious liquid to form gold (silver) mud.
2. The method of extracting gold from carbon slurry
is to put activated carbon into cyanide slurry, adsorb the dissolved gold on the activated carbon, and then extract it from Extracting gold from activated carbon mainly includes leaching raw material preparation, stirring leaching and countercurrent carbon adsorption, gold-loaded carbon desorption, electrowinning electrolysis, smelting ingot making, carbon regeneration and other operations.
Preparation of leaching raw materials: When using the carbon leaching method to extract gold, the preparation of leaching raw materials includes physical crushing and grinding Grading. Usually, the overflow fineness of the grinding classification of the carbon leaching gold extraction process is mostly -200 mesh, accounting for 85-95%.
Chip removal operations:Generally, two chip removal operations are required during the grinding process, one at the overflow of the first and second stages of grinding and classification. Most chip removal equipment uses medium-frequency linear vibrating screens. The mesh size of the chip removal screen must be as small as possible while ensuring that the screen surface does not flow.
Concentration operation before leaching: When the overflow concentration of grinding and classification is mostly 18-22%, direct leaching is not suitable and the slurry must be thickened. It is recommended to use a high-efficiency thickener with small footprint and high concentration efficiency.
Stirring leaching and countercurrent carbon adsorption:In the CIP gold extraction process, leaching and adsorption are two independent operations. The leaching process has been basically completed during adsorption; in the CIL gold extraction process, leaching and adsorption are carried out at the same time, and the leaching operation takes longer than the adsorption operation. Therefore, the size, aeration and dosing of the tank are determined by the leaching parameters, usually while leaching. Add 1-2 levels of presoaking before smoking.
Gold-loaded carbon desorption and electrowinning electrolysis: Add anions that are easily adsorbed by activated carbon into the desorption system to replace Au(CN)2- to achieve gold desorption; desorption The precious liquid obtained from gold-loaded carbon is recovered by ionization method to obtain solid gold.
Smelting to make ingots: After pickling and impurity removal, the gold mud obtained can be directly smelted into gold ingots. Using hydrometallurgy, the purity of gold ingots can reach over 99.99%.
Carbon regeneration: The desorbed activated carbon is first washed with acid to remove carbonate and other accumulations. After being returned to use several times, it needs to be thermally activated to restore the adsorption of the carbon. active.
The percolation and cyanide gold extraction method is based on the cyanide solution permeating through the ore layer to leach the gold from the gold-bearing ore. , mostly suitable for placers and loose and porous gold minerals. The methods are mainly two methods: pool leaching and heap leaching.
Pool leaching gold is generally carried out in a percolation leaching tank. During leaching, the ore is loaded into the tank and a leaching agent is added above the tank. , the leachate flows out from the lower part of the false bottom.
Heap leaching gold extraction is to transport the mined ore directly to a prepared stockyard Build a pile (or directly on the piled waste rock or low-grade ore), and then spray (or percolate) the cyanide leach solution to cause the solution to pass through the ore to produce a percolation leaching effect. The leach solution is circulated multiple times, repeatedly Spray the ore heap, then collect the leachate, and then use ion exchange resin, activated carbon adsorption or zinc replacement, and the lean liquid is returned to the heap leach operation for recycling. This method has low production cost, can be put into production quickly, and the heap leaching scale can be large or small.
Flotation gold extraction is mainly suitable for processing sulfide content with high floatability. Gold minerals are gold ores that are first flotated into copper and lead concentrates, and then gold is extracted from these concentrates, so comprehensive recycling of multiple metals can be achieved. At present, common flotation gold extraction processes include: flotation-concentrate cyanide leaching method, flotation-concentrate thiourea leaching method, flotation-concentrate roasting-high acid washing-cyanide leaching method, etc.
This gold extraction method is mostly used to process gold ores containing gold-bearing quartz veins and gold-bearing pyrite quartz veins. Using xanthate as collector and pine alcohol oil as foaming agent, gold concentrate is flotated from weakly alkaline pulp. The flotation concentrate is then subjected to cyanide leaching, the gold is dissolved by cyanide, the complex enters the solution, and then zinc powder is used to replace it to obtain gold mud. Finally, pure gold is obtained through gold mud fire smelting.
This gold extraction method is suitable for treating high arsenic and sulfur content. Or vein gold ore with high carbon content and muddy content, first use flotation method to obtain gold-containing sulfide concentrate, and then leaching the flotation concentrate with thiourea to recover gold.
For flotation concentrates containing high arsenic and sulfur content, the cyanide tailings are flotation Finally, sulfur, iron, arsenic and other impurities are enriched into the concentrate to become a high-sulfur and high-arsenic concentrate that is difficult to select. When direct cyanide leaching is not possible, the flotation gold concentrate can be oxidized and roasted first to remove arsenic. and sulfur, so that the roasted sand has a loose structure, which is more conducive to the leaching of gold and silver. Subsequently, high acid pretreatment and washing are used, and most of the impurities are dissolved by the acid and removed by washing to obtain gold concentrate.
Gravity separation and gold extraction mainly rely on the density and density between minerals. Mineral processing based on particle size differences is mostly suitable for processing a certain amount of coarse-grained free gold (+0.1mm) (such as placer gold or vein gold recovering monomeric dissociated coarse-grained gold before and after flotation and leaching). There are three main methods: jig gold selection method, shaker gold selection method and chute gold selection method.
Jig gold beneficiation method is suitable for selecting coarse mineral particles. The size range of metal mineral beneficiation is 0.074-50mm. For placer gold beneficiation, it can be Under the premise that the specific gravity difference is ≥1.25 and the ore monomer is dissociated, the lower limit particle size can reach 0.04mm. The process operation is simple and the equipment has large processing capacity. It has good application effect in roughing gold ore. The main equipment used is the jig.
Shaking table gold selection is carried out in horizontal medium flow, which is generally suitable for Processing and sorting of minerals with finer particle size (0.019-3mm) can be divided into three types according to the particle size of the ore: coarse sand bed, fine sand bed and mud bed. Commonly used equipment is 6s shaker, xs shaker, etc.
Coarse sand bed:Suitable for sorting mineral particles with a particle size between 0.5-2.0mm;
Fine sand bed:Suitable for processing mineral particles with a particle size range of 0.074-0.5mm;
Ore mud bed:Suitable for processing materials Mineral particles with a particle size of 0.037-0.074mm.
Chute gold separation uses inclined water flow for separation. It is mostly suitable for processing micro-fine materials with low mud content. The material particle size range is 0.03 -0.6mm, the main equipment is spiral chute.
The above is an introduction to the gold extraction methods commonly used in gold concentrators. As for which method to choose, it depends on the properties of the gold ore and cannot be chosen blindly. Therefore, the editor recommends conducting mineral processing tests and customizing suitable gold ore processing technology solutions and suitable gold ore processing equipment in stages through the tests.
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