Gold extraction from refractory gold mines using bio-oxidation technology

     Refractory gold ore was once known as Refractory Gold. Gold refers to a state of being extremely fine interference sulfide, arsenic compounds, gangue package, or arsenic during the leaching of gold, antimony, organic harmful substances, such as carbon, gold difficult to recover gold by conventional cyanidation . Before the cyanide is extracted, the ore must have a pretreatment process, which is to decompose the gold-bearing minerals in advance, fully expose the gold, and decompose or change the properties of the harmful substances to eliminate their disadvantages to the gold leaching process. influences. The ore after pretreatment can be golded by conventional methods.


     The refractory gold deposits are all primary ore. Except for a small amount of gold wrapped in the gangue, it is difficult to recover. The gold-bearing minerals are basically sulphur-containing and arsenic-containing minerals. These minerals have excellent floatability and can be floated. The method is rich in gold concentrate. In the process of enrichment, about 90 % of the tailings are discarded, and elements such as gold, silver , arsenic, iron and sulfur are obviously enriched in the gold concentrate, which creates favorable conditions for the pretreatment process.


     In order to break through the gold extraction process of difficult gold mines, the gold science and technology workers in our country have turned a large number of “staying mines” that have been put on hold after exploration into valuable resources that can immediately create wealth, and have worked hard for decades. At the end of 2000 , China's first bio-oxidation-cyanide gold extraction plant for processing arsenic-containing gold concentrates was completed and put into operation at the Yantai Gold Smelter in Shandong. The plant adopts China's own strains, all of which use equipment manufactured in China. After more than two years of production practice, it has acquired refractory gold concentrates from all over the country. After biooxidation pretreatment, the cyanide leaching rate has stabilized at 96 %. Above, the pre-processing costs have dropped below 250 yuan. Has achieved good economic and social benefits. The achievement of this achievement is a powerful indication that the refractory gold mine can not only be processed, but its investment and cost are fully acceptable. If converted into raw ore calculations, the cost of pretreatment increase is about 20 yuan per ton of ore , which is not a large proportion of the total cost of gold mining, selection and smelting. Of course, in order to pay for the added cost of the pretreatment process, the mining grade of refractory gold mines should be higher than conventional gold mines.


     The state attaches great importance to the application of bio-oxidation technology in the gold industry and has given strong support. In July this year , the National High-tech Industrialization Demonstration Project “Biooxidation and Gold Extraction Project” and the “Fifth Key Golden Science and Technology Research Project Industrialization Base” initiated by the Ministry of Science and Technology were established in Fengli Tianli Gold Industry, Fengcheng City, Liaoning Province. The limited liability company is put into production. The 100 ton/day bio-oxidation-cyanide gold extraction plant provides good conditions for the development of bio-oxidation pretreatment technology in China.


     Although the application of bio-oxidation technology in China's gold industry started late, it is developing very rapidly because it conforms to China's national conditions. Since 2000 , China has launched a new bio-oxidation-cyanide gold-plating plant every year. At present, China has become the country with the largest number of such factories in the world. It is not only related to the objective situation of China's difficult to deal with gold resources, wide distribution, and scattered mine sites, but also has some obvious advantages compared with other processes for processing such raw materials:


     1. The scale of construction can be large or small. It is very suitable for many gold mines in China, which are located in remote mountainous areas, which are small in scale but relatively concentrated in some areas.

     2 , equipment manufacturing is relatively easy, domestic can solve.

     3. Consumable materials are easy to supply.

     4 , production operations are easy to master.

     5. The factory does not emit waste gas or waste water, and does not produce products such as sulfuric acid and arsenic that are difficult to transport. The discharged solid waste meets national emission standards and can be stored or landfilled for a long time.


     Of course, the bio-oxidation process is not a panacea. Before deciding to build a factory, you must have an experienced research institute to conduct the test. It is considered that it is suitable for the local ore properties before the factory can be built according to the prescribed procedures.

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