Pretreatment method before gold extraction gold ore containing arsenic
In order to expose the gold is disseminated ore pyrite wrapped arsenic, arsenic minerals To eliminate the influence of the cyanide leaching of gold, gold ore containing arsenic several common pretreatment method.
1. Calcination Oxidation Method The arsenic gold ore is placed in a one-stage (or two-stage) roaster or in a rotary kiln, and calcined at 650 to 800 °C. Dearsenic is removed in a lower temperature, weak oxidizing atmosphere, and desulfurized in a higher temperature, oxidizing atmosphere. China's rotary kiln (7 tons / day) roasting arsenic-bearing gold ore, arsenic volatilization rate of more than 99%, sulfur volatilization rate of about 80%, arsenic recovery rate of up to 90%.
2. Pressurized oxidation method In a pressurized container, oxygen (or air) is introduced into the acidic (or alkaline) slurry of arsenic gold ore, and arsenic and sulfur are oxidized to arsenate and sulfate, thereby causing arsenic and sulfur. Mineral-coated gold particles are exposed for cyanide leaching. The temperature during pressurization oxidation was 170 to 190 ° C, the pressure was 1500 to 2000 kPa, and the treatment time was 2 hours. The leaching rate of gold after treatment by this method can be increased from 5 to 74% to 87 to 99%.
3. Bacterial Oxidation Bacterial leaching is carried out at 25 ° C at room temperature in three steps: 1) cultivation of Thiobacillus ferrooxidans in a bacterial culture medium to prepare a sulfuric acid bacterial leachate having a pH of 1.5 to 2.5; 2) bacterial catalysis, oxidative removal of arsenic, Sulfur; 3) The slag obtained after pretreatment is further cyanidated. The pretreatment solution activates the bacteria and then reuses them. South Africa used this method to leach -75 micron arsenopyrite. At pH 1.7, after 7 weeks of pretreatment, the ore cyanide leaching rate increased from 8.6% to 89.8%.
4. Other methods add a catalyst to accelerate the chemical oxidation process of arsenic mineral decomposition; use a highly conductive alkali (NaOH) solution as a medium to make the slurry undergo electrooxidation pretreatment under the action of the electrode; use the strong oxidizing property of nitric acid to arsenic And a nitric acid oxidation process in which sulfur is oxidized to arsenious acid and sulfuric acid.
Among the above various methods, the calcination oxidation method is widely used, and the investment in the pressurized oxidation method is relatively high, and the bacterial oxidation method is relatively low in investment and production cost, but the bacterial reproduction requires suitable conditions, and the reaction time is long, so Affected the industrial application of the law.
Method for treating carbonaceous gold ore
When the ore contains graphite or other carbonaceous materials, the ore is difficult to recover gold by cyanidation. Because carbon adsorbs gold cyanide complex, it increases the loss of gold and silver in tailings. Therefore, in the treatment of carbon-bearing gold ore, it is first necessary to distinguish the form of carbon in the ore (graphite, organic carbon, activated carbon, etc.), determine the adsorption capacity of carbonaceous materials for gold, and analyze the symbiotic relationship between carbon and gold. According to the form of carbon in the ore and the relationship with gold, the following methods can be used:
1. When the carbon in the ore does not contain gold, the carbonaceous material may be floated with non-polar oil, stored or discarded as a carbon concentrate, and the tailings are treated by a flotation cyanidation process. When a mine in a foreign country treats carbon-bearing gold ore, the original gold recovery rate is only 50% when there is no pre-foaming process. The process is changed to re-election-heavy tail carbon-tailing pyrite-floating cyanide The combined process, the recovery rate of gold reached 86%.
2. When the carbon in the ore does not contain gold, it is also possible to suppress the carbonaceous material and float the gold-containing sulfide. The inhibitor is Aro 633 (organic colloid), the dosage is 50-450 g / ton, the amount should not be too much; aniline black (C38H27N3) can also be used as an inhibitor because it has a large specific surface, adsorbs organic matter and does not adsorb Quartz and pyrite, so that carbonaceous materials are inhibited.
3. When the carbonaceous compound contains gold, the carbonic acid compound and the pyrite may be completely oxidized by oxygen and chlorine by chemical oxidation, and the oxidized pulp may be cyanated.
Among some carbon-bearing gold ore in the Carlin mine in the United States, carbonaceous compounds contain high levels of gold. In the production, a chemical oxidation method called carbon dioxide removal process called "double oxidation" can achieve a recovery rate of 86%. The specific process is as follows: firstly, air is introduced into the slurry with a temperature of 80-86 ° C at a speed of 8.5 to 9.2 m 3 /min, the ventilation time is 12 hours, the concentration of the slurry is 40 to 45%, and then into the slurry. Add lime and stir with chlorine gas (chlorine consumption is 22.7 kg / ton). Chlorine reacts with lime to produce calcium hypochlorite. The latter reacts with non-oxidized carbonaceous material and pyrite to make carbon in ore. The material and pyrite are completely oxidized, and the treated slurry enters the cyanidation operation.
Processing method of gold- bismuth concentrate
Because niobium minerals are easily soluble in alkaline cyanide solutions, niobium minerals can seriously affect the cyanide leaching of gold. There are several common methods for separating gold and antimony minerals:
1.8 to 10% sodium sulfide solution is a good solvent for stibnite and some cerium oxide minerals. Usually, at 80 to 90 ° C, when the slurry concentration is not less than 33%, the gold and strontium in the ore can be separated by leaching with the above solution for 1 to 2 hours. After the residue was washed with water, gold was recovered by cyanidation.
2. The gold-bismuth concentrate can be calcined by evaporating the antimony trioxide. Usually, the calcination is carried out in two stages, the first stage is calcined at 500 to 600 ° C for 1 hour, and the second stage is calcined at 1000 ° C for 2 to 3 hours. The antimony trioxide is recovered by a dust collector, and after the calcination is leached with dilute sulfuric acid, the gold is recovered by cyanidation.
3. The hot leaching in the medium of oxygen and ammonia solution can recover gold from the gold-bismuth concentrate. When the concentration of ammonia hydroxide in the solution is 33 to 35%, the temperature is 170 to 175 ° C, and the oxygen pressure is 15 to 16 atm, the leaching time is 24 to 30 hours, and 99% of gold can be recovered in the gold-rich concentrate.
4. Gold is leached from the gold-rhenium concentrate using an acidic thiourea [CS(NH2)2] solution with an oxidizing agent. When the concentration of thiourea in the solution is 0.1 to 1%, the concentration of sulfuric acid is 0.1 to 0.5%, and the concentration of oxidizing agent is 0.001 to 0.1%, the leaching rate of gold can reach 60 to 70%.
Gold- selenium ore processing
Gold selenium ore usually contains selenium 0.05-0.2%, because selenium is dissolved in cyanide solution, which complicates the cyanidation process (increased cyanide consumption and selenium film on the surface of zinc , making gold difficult to be replaced by zinc) . Therefore, the gold-selenium ore is processed by the following method before extracting gold:
1. For ores containing less than 0.05% selenium, a low concentration cyanide solution should be used for cyanidation to reduce the solubility of selenium. At the same time, when replacing gold with zinc powder, the solution must be increased, preferably by cyanidation with activated carbon. Gold is adsorbed in the solution, and the concentrate can be calcined at 600 to 700 ° C, and the calcination is carried out by cyanidation.
2. For ores containing more than 0.05% selenium, it is best to use a bleaching powder solution to leach selenium from the ore and then recover the gold by cyanidation. Selenium leaching can be carried out by diafiltration and stirring. The percolation bleaching powder consumption is several tens of kilograms per ton of ore, and the recovery rate of selenium is 90%; the consumption of stirring bleaching powder is less, but the recovery rate of selenium can reach 98 to 100%. The exudate can be used to precipitate selenium from solution with sulfur dioxide and iron filings.
Laser Cutting Engraving Machine
Laser Cutting Engraving Machine,Laser Engraving Machine,Laser Engraving Cutting Machine,Tabletop Laser Engraving Machine
Shandong Meiman Laser Technology Co., Ltd. , https://www.meimanlasers.com