By: FTM Machinery April 20th,2022
Graphite ore is metamorphosed by high pressure, and it is generally blue-gray, and after weathering, it is yellow-brown or gray-white. According to the characteristics of scaly graphite ore deposits and the properties of ore, the purification methods are also different. The beneficiation methods of graphite ore mainly include flotation purification method, alkaline acid purification method, hydrofluoric acid purification method, chlorination roasting purification method and high temperature method.
1、Flotation purification method
Flake graphite ore has good floatability, so flotation can better separate graphite from other impurity minerals. In order to effectively protect the graphite flakes and improve the yield and grade of large graphite flakes, the process plant adopts the multi-stage regrinding and multistage re-selection process of the coarse concentrate, which can screen out the dissociated large flake graphite in time, and also prevent the flakes from being damaged. Repeated grinding and breaking.
The flotation purification method is mainly suitable for low-carbon flake graphite, which can effectively protect the graphite flakes and improve the grade of graphite, and has low production cost and low energy consumption.
2、Alkaline acid purification method
The alkali-acid purification method is mainly composed of alkali melting process and acid leaching process.
Alkali melting process: Taking advantage of the acid and alkali resistance of graphite, sodium hydroxide and graphite are mixed in a certain proportion and then calcined at high temperature. In the molten state, the alkali and some impurities in the graphite react chemically to form water-soluble or acid-soluble salts , and then carry out water elution to remove silicon to realize the purification of graphite.
Acid leaching process: Acid leaching is carried out on the product after alkali melting and desilication, so that impurities that do not react with alkali in the melting process react with acid and are converted into soluble salts, and the graphite is purified by water washing and other processes.
The alkaline-acid purification method is mainly suitable for medium carbon graphite and high carbon graphite ore. The process method has simple equipment, strong applicability, small one-time investment, and can obtain high-grade graphite. However, the process needs to be carried out at high temperature, and the energy consumption is large, the chemicals used are easy to corrode the equipment, and the water consumption is large.
3、 Hydrofluoric acid purification method
The hydrofluoric acid purification method is to mix graphite and hydrofluoric acid, and react at a certain temperature for a period of time to generate water-soluble compounds or volatiles, and then eluted with water to remove impurities, dehydrated and dried to obtain purified Graphite products.
The hydrofluoric acid purification method is mainly suitable for the purification of high carbon graphite ore. The technological process is simple, the graphite ore has high purification grade and low cost. However, hydrofluoric acid is volatile and highly toxic. Improper use will cause safety accidents and environmental pollution. Therefore, safety precautions must be taken during use, and the generated wastewater must be treated centrally before it can be discharged.
4、 Chlorination roasting purification method
The chlorination roasting purification method is to mix graphite and reducing agent in a certain proportion, and then roast at high temperature in designated equipment. Impurities in graphite will be decomposed into oxides such as SiO2, Al2O3, Fe2O3, CaO, etc. at high temperature. These oxides will react with chlorine gas and will be converted into chlorides in meteorological or condensed form. It vaporizes and escapes, thereby achieving graphite purification.
The chlorination roasting purification method is mainly suitable for the treatment of silicate-containing graphite ores, and the purification efficiency is high, but the reducing agent chlorine gas is toxic, which will cause equipment corrosion and environmental pollution. It is rarely used in actual production.
5、 High temperature method
The physical purification of flake graphite ore mainly adopts the high temperature method. The melting point of graphite is 3773K, and its melting and boiling point is higher than that of silicate, second only to diamond, and it is one of the substances with the highest melting and boiling point in nature. The graphite ore is added into the graphite crucible, inert gas and protective gas are introduced under certain conditions, and heated with special equipment. When the temperature reaches 2700 °C, the impurities are vaporized and escaped, so as to achieve the purpose of graphite purification. The high-temperature purification method has high purification efficiency, and the purity of graphite can reach 99.99%, but the high-temperature purification of graphite ore will be affected by many factors, and the process energy consumption is high, the equipment and raw materials are very demanding, and the investment is large.
The above is the common graphite ore beneficiation process. As for which one to choose, it is necessary to determine the mineral properties of the flake graphite ore according to the beneficiation test, and select the appropriate supply process to obtain the ideal graphite concentrate.