In addition of the cyanidation leaching method, flotation and gravity separation are also used in gold ore processing. The gold flotation separation method is also a common gold ore beneficiation method, which is mainly used in extracting associated gold in polymetallic ore, removing impurities of gold extracted by cyanidation and so on.
Flotation separation method is a relatively complicated method of mineral processing. When using gold flotation method to separate gold ores, the range of parameters determined by the beneficiation test and the production needs of the beneficiation plant are adjusted to determine specific mineral processing schemes for different gold ores to achieve ideal recovery and gold concentrate grade.
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Gold flotation method is the main processing method for gold-bearing sulfide ores. The main characteristics of this kind of ores are often gold, silver, lead, sulfur and other minerals. Metal minerals include pyrite, sphalerite, galena, chalcopyrite, etc. Gangue minerals are mainly quartz, and include calcite, barite and other minerals. Gold minerals have similar flotation properties with sulfide minerals, especially with copper sulfide minerals. Therefore, the flotation process of gold ore is similar to that of copper sulfide minerals.
Collectors used in gold flotation include xanthate, black powder, ammonium black powder, etc. Usually there are two ways to use one or several collectors separately. Commonly used foaming agents include terpineol, alcoholic oil, 730 series foaming agents, etc. Inhibitors include lime, sodium sulfide, dichromate, etc. Therefore, how to select the composition of the agent should check the specific properties of the ore.
Due to the complexity of the disseminated relationship of this type mineral, We need to control the appropriate grinding fineness. It is necessary to do mineral dressing test before confirming the grinding fineness and reagent system.
Arsenic not only has a great impact on the quality of gold concentrate ore, but also pollutes the environment. Arsenic in gold ore is generally found in arsenopyrite, the gangue mineral, and it is more closely disseminated with gold minerals and is more difficult to separate.
The common methods for reducing the content of arsenic in the concentrate is the soda method, the lime method, the oxidation method. Among them, the oxidation method is a relatively more effective and widely used method. The main principle of this method is oxidizing the surface of the arsenic mineral and inhibiting the arsenic mineral by adding the oxidizing agent to increase the content of free oxygen in the aqueous solution.
On the basis of inhibition of arsenic, the content of free oxygen in water can be increased and the floatability of arsenic minerals can be lowered by adjusting pH and temperature, so that the content of arsenic in gold concentrate is reduced. Generally, arsenic minerals have good floatability under weakly acidic conditions, while under neutral and weakly alkaline conditions, the floatability of arsenic minerals is reduced, and gold minerals still have good floatability under such conditions. Normally, we adjust the PH value to 8 to separate the arsenic-containing gold ore by gold flotation.
For different arsenic-bearing gold mines, the specific oxidants, PH values, and temperature ranges are different. Hence, it is more scientific and rational to determine appropriate conditions by doing mineral processing test.
The organic carbon minerals in the gold ore not only have good floatability, but also have strong adsorption power, which not only affects the gold concentrate grade, but also wastes a lot of flotation reagents. Therefore, it is necessary to reduce the influence of organic carbon on gold flotation through decarburization.
Decarburization can be achieved by roasting, adding agents and other methods. Roasting is mainly aimed at gold ores with high carbon content. For gold ore with relatively low carbon content, carbon can be firstly selected by sodium silicate, no. 2 oil and kerosene, and the floatability of carbon inhibited by CMC can also be added into pulp. However, the method of adding inhibitors has a great impact on the recovery of gold ore, so the organic carbon in gold ore can be removed by selecting carbon first.