Antimony bearing gold ore is an important part of China’s gold resources. Its remarkable feature is that gold is wrapped in fine particles or disseminated in sulfide such as stibnite, arsenopyrite and pyrite. It is a kind of refractory gold ore. Due to the distribution of gold fine particles in antimony bearing gold ore and the cyanide and oxygen consumption of stibnite, the index of conventional direct cyanide leaching is not high. The common beneficiation methods of antimony gold ore mainly include flotation method, pretreatment method and enhanced leaching method. Next, Fodamon engineer explains as follows.
Antimony gold flotation
Antimony gold ore flotation method is mostly used to treat ores in which antimony minerals are not the carrier minerals of gold. Its essence is the flotation separation of antimony minerals and gold carrying minerals such as sulfur and arsenic, which can avoid complex pretreatment links and obtain by-product antimony concentrate. The cost is relatively low, but the operation is difficult. It is necessary to ensure the flotation index of antimony concentrate and reduce the entrainment of gold as much as possible.
Generally, antimony gold flotation can be divided into mixed flotation and preferential flotation.
The mixed flotation process is relatively simple, but it is difficult to suppress the gold carriers such as sulfur and arsenic that have floated, resulting in the mixing of some minerals such as sulfur and arsenic into the antimony concentrate, affecting the quality of the antimony concentrate and causing the loss of gold in the antimony concentrate.
In principle, preferential flotation can be divided into preferential flotation of gold bearing minerals such as arsenic and sulfur and preferential flotation of antimony. However, in the process of preferential flotation of arsenic and sulfur, some antimony minerals with good floatability will float together, resulting in large loss of antimony in gold concentrate. At the same time, a large amount of acid needs to be added in the next flotation of antimony to reduce the pH value, which increases the investment cost and is not friendly to the environment.
Therefore, most antimony gold flotation plants often adopt the preferential flotation process of antimony. The key of this process is the efficient collection of antimony minerals and the effective inhibition of gold carrying minerals such as arsenic and sulfur.
Antimony gold ore pretreatment method
When the antimony grade in the raw ore is low and has no recycling value, or gold exists in antimony minerals, it is difficult to eliminate the influence of antimony by flotation. In order to improve the cyanide leaching environment of antimony bearing gold ore, physical or chemical pretreatment can be used before leaching to achieve high-efficiency leaching of real cash. The common pretreatment methods of antimony gold ore mainly include roasting method and chemical alkali leaching method.
Roasting is a common method for oxidation pretreatment of antimony containing gold ore. by roasting, the physical structure of the ore is changed to produce loose and porous calcine. At the same time, stibnite is transformed into antimony containing oxide in oxidizing high temperature atmosphere, so as to eliminate the adverse effects of wrapping and stibnite.
The leaching rate of antimony bearing gold ore roasting method is high and the process is mature, but its associated minerals such as arsenic and sulfur will cause environmental pollution problems, which need to be reprocessed, with high energy and power consumption.
Chemical alkali leaching
Chemical alkali leaching method is mostly used to treat gold antimony ore with stibnite as the main gold carrying mineral. This method uses the characteristics that antimony minerals can be well dissolved in alkali or sodium sulfide, and removes such products in advance through water washing, so as to avoid the occurrence of cyanide and oxygen consumption reaction during subsequent cyanide leaching, and significantly weaken the secondary coverage of NaCNS and other products.
Compared with roasting method, the cyanide leaching rate of chemical alkali leaching method will be reduced, but it has the advantages of fast reaction, short cycle, less pollution and low cost.
Enhanced leaching of antimony gold ore
The enhanced leaching of antimony gold ore is mainly used in the cyanide leaching stage of antimony containing gold ore. on the one hand, the cyanide and oxygen consumption reaction of stibnite in the cyanide leaching system is inhibited by adding leaching aids such as lead acetate and lead nitrate, so as to avoid the secondary coverage of gold particles by its reaction products; On the other hand, potassium permanganate and other oxidants are added to accelerate the oxidation of stibnite to form antimonate, destroy the peripheral coating of gold, improve the activity of gold cyanide leaching reaction and accelerate the leaching rate.
The enhanced leaching method does not need pretreatment of raw ore, and can accelerate the leaching rate and improve the leaching efficiency, but it is not suitable for antimony gold ore with serious gangue wrapping.
In short, the difficulties in the separation of antimony bearing gold ores lie in the wrapping of gold by antimony minerals and the consumption of cyanide and oxygen in the leaching of stibnite. For different antimony gold ore properties, different separation methods need to be used for recovery. For this kind of refractory gold ore, it is necessary to conduct beneficiation test first. After fully understanding the ore properties, select scientific and reasonable beneficiation methods and equipment for antimony gold ore according to the beneficiation test report, and do not apply them arbitrarily.