{"id":11212,"date":"2021-05-23T14:44:21","date_gmt":"2021-05-23T11:44:21","guid":{"rendered":"https:\/\/drago-met.ru\/?p=11212"},"modified":"2024-03-22T17:39:59","modified_gmt":"2024-03-22T14:39:59","slug":"kuchnoe-vyshhelachivanie-zolota-etapy-tehnologiya-i-tonkosti-metoda","status":"publish","type":"post","link":"https:\/\/drago-met.ru\/en\/dobycha-i-affinazh\/kuchnoe-vyshhelachivanie-zolota-etapy-tehnologiya-i-tonkosti-metoda\/","title":{"rendered":"Heap leaching of gold: stages, technology and subtleties of the method"},"content":{"rendered":"

Pure Gold<\/a> is not found in nature. It is mined in ores and extracted from gold-bearing veins. One of the active methods gold mining<\/a> - heap leaching of gold.<\/p>\n\n\n\n

Heap leaching is the most cost-effective method of extracting gold from ore. Geography of application of the method<\/h2>\n\n\n\n

Heap leaching process gold<\/a> is considered environmentally safe, highly profitable, so it is successfully used by countries in Europe, America and Southeast Asia. Despite the simplicity in application, the technology is carried out using modern tools and requires clear step-by-step instructions.<\/p>\n\n\n\n

\"Heap<\/span>
Heap gold leaching technology<\/span><\/strong><\/figcaption><\/figure>\n\n\n\n

The leaching method is the treatment of gold-bearing ores<\/a> with special solutions. All the chemical elements begin to interact with each other, and the electrophysical processes<\/a>The gold is leached in certain compositions and is further processed through filters. The pure metal is obtained in the last step by electrolysis.<\/p>\n\n\n\n

Technology of the gold leaching process<\/h2>\n\n\n\n

To produce the process<\/a> heap leaching, it is necessary to prepare a site and an underlying pad. The latter is necessary to hold the solution inside the area where the process will take place. It is necessary to make calculations in order to gold-containing<\/a> the stack was held within the specified parameters.<\/p>\n\n\n\n

Project planning and preliminary calculations<\/h3>\n\n\n\n

When planning gold mining<\/a> through heap leaching, we need to consider the factors that determine the success of the project.<\/p>\n\n\n\n

    \n
  1. Plan drilling programs. Test the area where the technology is planned to be applied.<\/strong><\/li>\n\n\n\n
  2. Compare with similar projects.<\/strong><\/li>\n\n\n\n
  3. Determine what impurities are in the ore. This will help you understand how long the leaching will last and what the level of gold will be.<\/strong><\/li>\n\n\n\n
  4. Identify the type of ore.<\/strong><\/li>\n\n\n\n
  5. Determine the gold and silver content.<\/strong><\/li>\n\n\n\n
  6. Decide on the method of building a pile: it is better to refer to the experience of colleagues.<\/strong><\/li>\n\n\n\n
  7. Create a reliable testing ground for the work.<\/strong><\/li>\n\n\n\n
  8. Hire the necessary specialists.<\/strong><\/li>\n\n\n\n
  9. Strictly supervise the work.<\/strong><\/li>\n\n\n\n
  10. Conduct test work and analyze the results.<\/strong><\/li>\n<\/ol>\n\n\n\n

    In addition, you should be prepared for unforeseen results. The weather may change, contractors may fail. The characteristics of the ore may also change. It is important to calculate the financial costs and profits, to calculate the possible risks at each stage of the work.<\/p>\n\n\n\n

    \"Heap<\/span>
    Heap gold mining technology<\/b><\/span><\/span><\/figcaption><\/figure>\n\n\n\n

    Raw material requirements and ore preparation<\/h3>\n\n\n\n

    Technology<\/a> is mostly applicable to the processing of low-grade ores, gold mines<\/a> small sizes. Sands, porous ores have a structure suitable for processing solutions<\/a> seeped to the gold particles.<\/p>\n\n\n\n

    \n

    Approximately 50% to 90% of gold can be extracted by leaching from oxidized ores, from waste rock dumps. It is practically impossible to obtain precious metal by heap leaching from ores containing sulfides, e.g., with thiourea, sorption-active carbonaceous substances.<\/p>\n<\/blockquote>\n\n\n\n

    To process a gold mine, depending on the amount of gold contained, its composition and filtration properties, the following methods are used:<\/p>\n\n\n\n

      \n
    1. Crushing. The leaching process requires fine gold. The ore is crushed to a particle size of 5-20 mm. Sometimes pieces up to 100 mm in size are allowed in the process.<\/strong><\/li>\n\n\n\n
    2. Screening is the sifting of ore to separate ore elements into size classes. The ore is sieved repeatedly, and the ore is crushed and crushed in between. In some cases, this step may be unnecessary and omitted.<\/strong><\/li>\n\n\n\n
    3. Shaking of clayey ores with rocky ores. Clay substances clog up the loose structure, interfere with the penetration of solutions to the gold particles, thereby making leaching more difficult. Therefore it is necessary to preliminarily burden the ore by adding cement, alkali, and lime. Some companies use these substances separately.<\/strong><\/li>\n\n\n\n
    4. Pelletizing of small and finely dispersed fractions. Dusty substances are turned into lumps: briquettes or pellets. In the future, the resulting material is easier to subject to firing.<\/strong><\/li>\n<\/ol>\n\n\n\n

      Also, the preparation of ore for gold leaching includes the construction of a landfill.<\/p>\n\n\n\n

      Construction of the site in the open air. Basic requirements<\/h3>\n\n\n\n

      Heap leaching technology is carried out in the open air. For this purpose special polygons are equipped, creating favorable conditions.<\/p>\n\n\n\n

      Preparation of the waterproofing layer<\/h3>\n\n\n\n

      Waterproofing is the most important step in site preparation. To make the landfill watertight, it is concreted, asphalted, or covered with a layer of compacted clay. Often a cheaper method of waterproofing is used - covering the site with synthetic film. Of modern shelters - geomembrane, a polymer consisting of synthetic materials, butyl rubber.<\/p>\n\n\n\n

      \"Preparation<\/span>
      Heap leach pad<\/span><\/strong><\/figcaption><\/figure>\n\n\n\n

      The site should be sloped 2-4 degrees, this is necessary to facilitate the drainage of residual materials. If the surface is naturally flat, it is sloped artificially. It is also important to prevent the mine from becoming weathered later on.<\/p>\n\n\n\n

      In addition, the site must be strong enough to hold the right amount of ore material, have a surface that is resistant to chemical attack, and be intact so that solutions do not leak out.<\/p>\n\n\n\n

      Stacking of ore in a heap with special equipment<\/h3>\n\n\n\n

      The correct formation of a stack, i.e. a pile, is the most responsible stage of the technology. The success of the whole process depends on it. The stacking of the pile must be done in such a way that there are no channels in it. The content of the stack must be homogeneous, friable and porous, and this is what the screening process is for. It is important that the ore mass be permeable to the cyanides used in the leaching process.<\/p>\n\n\n\n

      \n

      Special equipment, bulldozers and loaders, are used to backfill the pile. The pile itself has the shape of a truncated cone up to 15 meters high. One pile can contain from 100 to 200 thousand tons.<\/p>\n<\/blockquote>\n\n\n\n

      Ore irrigation solution<\/h3>\n\n\n\n

      Nozzles - special devices for sprinkling - are installed above the ore stacks. By means of nozzles, the piles are sprayed with cyanide solution at a rate of 0.15-3 cubic meters per square meter of ore. <\/p>\n\n\n\n

      \n

      The cyanide solution used has a concentration of 0.05 - 0.1 % NaCN, pH 10-11.<\/p>\n<\/blockquote>\n\n\n\n

      Drainage of mortar through the stacks (heap)<\/h3>\n\n\n\n

      Along the sides of the stack are installed plastic-finished ditches, pipes for drainage, i.e. for filtration. The ditches are filled with drainage material: it can be the ore mass itself with excellent permeability, gravel, sand. All pipes are connected into one collector, where the gold-containing solution flows.<\/p>\n\n\n\n

      \"Drainage<\/span>
      Heap leach pad<\/span><\/strong><\/figcaption><\/figure>\n\n\n\n

      Gold leaching<\/h3>\n\n\n\n

      Under the influence of the solvent, all gold-holding rocks are washed out. The solution containing gold descends from the top layers of the heap and flows out from under the bottom. It is collected in prepared drainage ditches, where it is cleaned of clay particles, and then sent to a common collector.<\/p>\n\n\n\n

      Collection of gold-containing solutions and sedimentation<\/h3>\n\n\n\n

      Gold in solution form must be refined from ore impurities. A common method is to dissolve these impurities with acids, tin and chlorine compounds. \u0412 at home<\/a> usually whitewash, aqua regia, hydrochloric acid, sodium chloride are used for this purpose. Iodide leaching is used.<\/p>\n\n\n\n

      \n

      In total, it takes up to 4 months to heap leach gold from ore.<\/p>\n<\/blockquote>\n\n\n\n

      Recovery of gold as cathode sludge (70-80%) or gold sludge (20-30%) by electrolysis<\/h3>\n\n\n\n

      In order to extract gold, productive solutions after heap leaching are subjected to electrolysis. With this method, high quality gold is obtained. The process follows the formula H2AuCl4 - 4H2O. The following is used as an anode gold-containing material<\/a>obtained by heap leaching. The cathode is a gold plate. Under the influence of current the gold particles are deposited on the plate. <\/p>\n\n\n\n

      \n

      At the bottom of the tank where the electrolysis takes place, a sludge is deposited - the remains of the gold-containing alloy.<\/p>\n<\/blockquote>\n\n\n\n

      \"Gold<\/span>
      Gold purified from impurities <\/span><\/strong><\/figcaption><\/figure>\n\n\n\n

      Sludge melting in a crucible or ore-thermal furnace<\/h3>\n\n\n\n

      The cathode gold-containing residues are melted in crucible and ore-thermal furnaces in two stages:<\/p>\n\n\n\n