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Click to add WeChatCarbonaceous gold ore refers to refractory ores containing organic carbon. The organic carbon components in these ores interfere with the gold leaching process through adsorption and chemical reaction, resulting in a low gold recovery rate. Carbonaceous gold ore has a large resource reserve, but due to its special ore properties, its development and utilization rate is low. With the growth of global demand for precious metals, how to improve the gold recovery rate of carbonaceous gold ore has become a key challenge in the mining industry. This article will talk about the gold extraction technology of carbonaceous gold ore beneficiation!
The carbonaceous materials contained in carbonaceous gold ore are mainly divided into solid carbon and organic carbon. Through adsorption and chemical bonding, carbonaceous materials react with gold to form cyanide complexes, thereby hindering the cyanide leaching of gold. This phenomenon is called the "carbon robbery gold" effect. Specifically, the complex formed by solid carbon and gold will occupy the position of gold ions in the cyanide solution, while organic carbon will reduce the leaching efficiency of gold by forming a combination with cyanide, seriously affecting the recovery rate of gold. Therefore, the "carbon robbery of gold" problem of carbonaceous ores is pretreated.
Roasting method: The roasting method heats the carbonaceous gold ore to a high temperature to oxidize the organic carbon in the ore into gas, thereby reducing the adsorption of carbon on gold. Although this method is effective, it has high energy consumption and may cause oxidation loss of metals. With the development of technology, the optimization of roasting equipment, such as internal circulation boiling roasting furnace, has significantly improved the leaching rate of gold.
Chemical oxidation method: The chemical oxidation method oxidizes the organic carbon in the ore by adding an oxidant (such as chloride or permanganate) to convert it into inorganic matter. This method has a fast reaction speed, but it also has a strong oxidizing effect on other impurities in the ore, which may bring about the problem of by-product treatment.
Biooxidation method: The biooxidation method decomposes carbonaceous substances through microbial metabolism. This method has low energy consumption and good environmental friendliness, but its scope of application is limited, and the growth conditions of microorganisms are relatively harsh, and the treatment cycle is long.
Covering inhibition method: The covering inhibition method reduces the adsorption of gold by carbonaceous materials by covering a layer of inhibitor on the surface of carbonaceous gold ore. This method is simple to operate, but has high requirements for the selection and covering effect of inhibitors, and may affect the subsequent leaching efficiency of gold.
Competitive adsorption method: The competitive adsorption method is to compete for the adsorption position of gold by carbonaceous materials in the ore by adding certain substances with strong adsorption capacity (such as certain inorganic salts). This method can effectively improve the recovery rate of gold, but it has a certain dependence on the selection and dosage of additives.
In order to overcome the limitations of a single pretreatment method, the combined pretreatment process has gradually become the mainstream technology for improving the recovery rate of gold. Common combined processes include:
Roasting + chemical oxidation: After roasting the ore to remove organic carbon, the residual organic matter is further decomposed by chemical oxidation, thereby improving the leaching efficiency of gold.
Roasting + biological oxidation: roasting is first performed to remove most of the organic carbon, and then the ore is treated by biological oxidation to decompose the remaining carbonaceous materials. This combined process combines efficient heat treatment with environmentally friendly biotechnology, which can effectively improve the gold recovery rate and reduce secondary pollution.
Flotation + covering inhibition: flotation is used to separate the gold ore first, and then the covering inhibition method is used to reduce the adsorption of carbon in the ore, effectively improving the gold recovery rate.
The combined pretreatment process can flexibly adjust the process combination according to the characteristics of different carbonaceous gold ores, give full play to the advantages of each pretreatment method, and has become a key direction for future research and application.
Flotation gold extraction is an important technology commonly used in gold ore beneficiation. In view of the special properties of carbonaceous gold ores, the flotation process needs to select a suitable flotation method based on the associated relationship between carbon and gold:
Priority flotation: During the flotation process, gold ore is preferentially separated to reduce the interference of carbonaceous materials, which is suitable for ores with relatively dispersed distribution of carbon and gold.
Mixed flotation: For ores with relatively close association of carbon and gold, mixed flotation can be used to improve the gold recovery rate by optimizing the ratio of flotation agents.
In the flotation process, the embedded particle size of gold ore is the key factor affecting the flotation effect. Too coarse or too fine particle size may lead to a decrease in flotation indicators, so it is crucial to reasonably control the particle size distribution.
Carbon-containing gold gravity extraction technology is a physical beneficiation method that uses the density difference between minerals for sorting. The carbonaceous gold ore is initially sorted by gravity separation, which is suitable for minerals with coarse ore particle size and high gold content.
Shaking table gravity separation: For minerals with large density differences between gold minerals and carbonaceous minerals, shaking table gravity separation is suitable. Through the action of water flow and shaking, stratification is formed in the ore pulp, and different components are sorted out according to the density difference of the minerals. Gold minerals are easily deposited in the lower layer due to their high density, while light carbonaceous minerals will be excluded or floated.
Jigging gravity separation: It is used for ores with larger particle sizes, especially when there is a significant density difference between gold minerals and carbonaceous minerals, the jigging gravity separation has a better effect. Equipment that uses gravity difference and vibration to separate minerals is often used for the separation of gold and heavy metal ores.
Chute gravity separation: For some sandy carbonaceous gold ores, the chute gravity separation method is more effective. The slurry flows along the chute under the action of gravity. The gold particles with high density separate and enrich the minerals of different densities under the combined action of friction, water flow resistance and gravity.
During the cyanide leaching process, the addition of specific shielding agents can effectively reduce the adsorption of gold by carbonaceous ores. Common shielding agents include fluorides, sulfides, etc. These substances can form stable complexes with gold, thereby preventing the reaction of gold with carbonaceous substances. In addition, the use of ion exchange resins can also improve the recovery rate of gold by selectively adsorbing gold ions.
Acid leaching is a method of dissolving metals in ores through strong acids (such as sulfuric acid, hydrochloric acid, etc.). For some carbonaceous gold ores, acid leaching can release gold minerals by dissolving carbonaceous materials in the ore. Acid leaching is particularly suitable for the treatment of gold in the ore when it coexists with other metals (such as copper, iron, etc.).
The roasting process has been widely used in the dressing of carbonaceous gold ores. The application of traditional roasting methods is limited to a certain extent due to its high energy consumption and possible oxidation loss of gold. However, with the advancement of roasting furnace technology, the emergence of new internal circulation boiling roasting furnaces has significantly increased the leaching rate of gold and reduced energy consumption, and has gradually become the mainstream roasting equipment.
Hot pressure oxidation pretreatment technology is a method that has developed rapidly in recent years, and is usually divided into alkaline and acidic medium treatment. In the research and development technology of Guizhou Zijin Mining, hot pressure oxidation pretreatment not only improves the gold recovery rate, but also successfully solves the problem of arsenic removal in the ore, becoming an important means of treating carbonaceous gold ores.
The above is an introduction to the gold extraction technology of carbonaceous gold ores, including pretreatment and smelting. Due to the particularity of the properties of carbonaceous gold ores and the "carbon robbery gold" effect, the gold recovery rate is low. In actual beneficiation plants, it is necessary to design suitable gold extraction schemes based on the properties of carbonaceous gold ores and beneficiation requirements. Gold ore beneficiation gold extraction technology has important application value in the treatment of carbonaceous gold ores. By reasonably selecting pretreatment methods and beneficiation processes, the gold recovery rate can be effectively improved. The development of gold ore beneficiation gold extraction technology will provide strong support for the efficient development and utilization of carbonaceous gold ores.
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