The successful development of Sandioss eco-friendly goldextraction method is a major innovation in the gold dressing industry, whichhas revolutionized the cyanidation gold extraction method worldwide for 100years, and can be regarded as a major breakthrough in the world environmentalhistory. Won the national invention patent and the certification of thenational authority, this technology does not change the original cyanidationequipment, does not change the original cyanidation process, because of theleaching speed, high recovery rate, strong adaptability to all kinds of ore,can on the property gold and other advantages. Eco-friendly gold leachingmethod will be the good news for gold production enterprises.
Generally, the eco-friendly goldleaching method can be divided into stirring and percolation. Among them,stirring is mainly used to treat flotation gold concentrate, or whole mud;However, the leachate is mainly used to treat low grade gold ores.
Gold Extraction by stirring process
Stirring goldextraction process mainly includes two kinds of gold extraction process. One isthe so-called zinc replacement process (CCD method and CCF method), which isused to replace precipitation with zinc powder (silk) after continuouscountercurrent washing. The other is no filtration and washing, using activatedcarbon directly from the pulp adsorption recovery of gold unfiltered carbonslurry process (CIP method and CIL method).
1. Zinc Replacement Process
Zincreplacement process (CCD method and CCF method) mainly includes preparation ofleaching materials, stirring leaching, solid-liquid separation bycounter-current washing, purification and deoxidation of leaching liquid, zincpowder (silk) replacement, pickling, smelting and other operations.
2. Gold Extraction from carbon pulp
Carbon pulpextraction process (CIP method and CIL method) is to put activated carbon into pulp,adsorb dissolved gold on activated carbon, and then extract gold from activatedcarbon, mainly including the preparation of leaching materials, stirringleaching and countercurrent carbon adsorption, gold-loaded carbon desorption,electrodeposition electrolysis, smelting ingots, carbon regeneration and otheroperations.
Carbon pulp method (CIP) : firstleach, then add activated carbon to adsorb gold in pulp;
Carbon leaching (CIL) : activatedcarbon is added to the leaching tank and the leaching and adsorption arecarried out simultaneously.
Leaching and adsorption are twoseparate operations in CIP process. In the adsorption operation, the leachingprocess has been basically completed, and the size, number and operationconditions of the adsorption tank are determined by the adsorption parameters.
In the CILprocess, leaching and adsorption are carried out simultaneously. In general,the leaching operation takes longer than the adsorption operation, so the size,aeration and dosing of the tank are determined by the leaching parameters.Since the adsorption rate is a function of the dissolved gold concentration inthe solution, in order to increase the concentration of dissolved gold in thefront adsorption tank and increase the leaching time, it is usual to add 1 ~ 2levels of preleaching before leaching and absorption.
Gold extraction by percolation
1. Heap leaching process
Heap leachingis mainly will transfer to prepared in advance of the ore mining yard on theheap, or directly on the storage of waste rock or low grade ores, leachingliquid spray or percolation, and make the solution produced by ore percolationleaching, leaching liquid cycle for many times, repeatedly spray ore heap, andthen collected leachate, reoccupy activated carbon adsorption or zincreplacement, the poor fluid return cycle used for heap leaching operations.
It is commonly chosen that theheap leaching sites are located in the hilly areas with a gentle slope (naturalgradient 5-15) close to the stope and convenient for transportation. Firstly,the weeds and floating soil are cleared and then the environment is rammed. Itis built into a foundation with a gradient of around 5 wine, with the height onboth sides slightly lower in the middle, so that the leach fluid can beconcentrated into the storage tank and the storage yard is covered withgeotechnical film to prevent leakage. Soil Banks of 0.4 meters were builtaround the yard and used as drains to prevent rainwater from flowing into theyard. A large lean ore 0.3 m thick is deposited before the ore is piled.
Heap leaching method has lowproduction cost and can be quickly put into production. The heap leaching scalecan be large or small, and each heap of ore can reach tens of thousands oftons. Heap leaching or pelletizing after ore crushing to a certain size.
2. Tankleaching process
Leach isusually carried out in a leach tank, usually wood tank, iron tank or cementtank. The bottom of the pool is horizontal or slightly inclined, round,rectangular or square. The tank is equipped with a clip bottom made of a porousacid-resistant plate, which is covered with a press cloth and covered with alattice with wooden or corrosion-resistant metal strips. When leaching, put theore in the pool, add the leaching agent above the pool, and the leaching liquidwill flow out from the bottom part of the clip. The bottom is used to filterand support ore. The leaching time of leachatedepends not only on the dissolution rate of mineral by solvent, but also on thepermeability rate of solvent in the material layer. However, the permeabilityrate mainly depends on the loading height, porosity, silt content, leachingagent viscosity and the characteristics of the material itself.
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