What is the development stage of lithium-containing minerals, the upstream raw materials of lithium batteries, and what developments are there in the extraction process of lithium ore?

　　After decades of research on lithium extraction technology from lithium ore, my country's lithium extraction industry has made great technological achievements. For lithium ore, the production rate of lithium has been increased from 60% to more than 80%, and the amount of slag discharge and energy consumption have been further reduced, which has made a great contribution to the development of my country's lithium battery raw materials business.

　　Lithium batteries are mainly composed of four parts: positive electrode active material, negative electrode active material, electrolyte, and separator. Among them, the negative electrode active material is usually carbon material, and the positive electrode material is mainly lithium-based materials.

　　As the world’s environmental problems intensify, countries and enterprises have accelerated the pace of human society’s transition to a clean and energy-saving society. Among them, the development of electric vehicles has contributed to the creation of fresh air and reduction of carbon emissions, occupying an important position in the new energy industry. At present, domestic car companies are accelerating the deployment of power batteries, and downstream demands have forced higher and higher requirements on materials and processes for power batteries. Lithium batteries are mainly composed of four parts: positive electrode active material, negative electrode active material, electrolyte, and separator. Among them, carbon material is often used as negative electrode active material, and lithium-based materials dominate the cathode material. So what is the development stage of lithium-containing minerals as the upstream raw material of cathode materials, and what developments are there in lithium extraction processes?

　　1. Overview of the development of the lithium industry

　　Supply and demand requirements are the core content of the product. According to the development of the lithium industry in the past two years, it will continue to maintain rapid development for a period of time. According to relevant data, the overall supply and demand of the industry in 2017-2018 and even the first half of 2019 are still in a tightly balanced state. From historical experience, it can be seen that the production of existing lithium resources is easily disturbed by climate and traffic, and the development of new resources is difficult, and the stability is also doubtful. The probability of a situation where supply exceeds demand is still relatively high.

　　2. Lithium extraction process from lithium minerals

　　There are more than 100 kinds of lithium-containing minerals in the mineral field, but the most abundant and high-grade lithium minerals are spodumene and lepidolite. The distribution of lithium resources in my country is shown in Table 1:

　　(1) Lithium extraction from spodumene

　　The lithium oxide content in the spodumene concentrate is about 5.0% to 8.5%. At present, the lithium extraction product of spodumene is mainly lithium carbonate, and its processes mainly include sulfuric acid production process, sulfate mixed sintering process, sodium chloride roasting production process, sodium carbonate pressure leaching production process and limestone roasting production process. The main production process is briefly introduced below.

　　①Sulfuric acid process

　　The 　　 sulfuric acid process is commonly used in industrial production. After the lithium ore is ground-roasted-leached, sulfate is added to remove impurities and filtered to obtain a lithium sulfate solution. The precipitated lithium carbonate is prepared from the solution and then washed and dried to obtain the product. This method has high yield and low requirements for lithium ore grade. The sulfuric acid process can also process lepidolite.

　　②Sulphate mixed sintering method

　　The spodumene concentrate and K2SO4 (or CaSO4 or a mixture of both) are mixed and sintered at a certain temperature. After a series of physical and chemical reactions, the metal elements in the added sulfate will replace the lithium in the ore to form solubility The main impurity of the sulphate, the main impurity is to generate insoluble compounds, and then the sintered clinker is leached and separated, and the lithium ions enter the solution, and the lithium carbonate product is obtained after purification, concentration, and precipitation.

　　③Sodium carbonate pressure leaching method

　　Firstly, the β-spodumene obtained by processing spodumene is ground to a certain degree of fineness, and a certain amount of sodium carbonate is added to mix it, and the pressure is leached in the reactor at 200°C, and then CO2 gas is introduced to form soluble hydrogen carbonate. The lithium solution is filtered to remove the residue (zeolite), heated to 95°C to expel CO2, precipitated, filtered, and the filter cake is dried to obtain a lithium carbonate product.

　　④Limestone roasting method

　　Limestone roasting method treats lithium-containing minerals to produce lithium carbonate. The production process includes raw meal preparation, roasting, leaching, slag washing, leaching solution concentration, purification, crystallization and other main processes. The main advantage of the lime method is that it is universal because it is suitable for decomposing almost all lithium minerals. The reaction process does not require scarce reagents.

　　(2) Lithium extraction from lepidolite

　　my country is rich in lepidolite resources. The lithium oxide content in lepidolite concentrates is about 2.0% to 5.0%. The lepidolite resources in Yichun, Jiangxi are relatively concentrated, with superior mining conditions, and contain expensive rubidium and cesium resources and a large amount of valuable resources. Resources aluminum, potassium and fluorine. At present, the lithium extraction process of lepidolite mainly includes limestone sintering method, sulfate roasting method, sodium chloride autoclaving method, sodium sulfate autoclaving method, lime autoclaving method and so on.

　　①Limestone sintering method

　　The limestone sintering process is similar to the spodumene lithium extraction process. It is the most mature method. The advantages of this method are more prominent: (1) The leaching process is short. (2) The leaching system is good, it is an alkaline system, and the equipment has little corrosion. (3) The separation process of lithium hydroxide is simple, and the output rate of potassium, rubidium and cesium is high. At the same time, its disadvantages are low yield, large amount of slag, and high energy consumption.

　　②Sulphate roasting method

　　The sulfate roasting method produces less slag and lower energy consumption. The yield is about 10% higher than that of the limestone sintering method. However, the use of this method leads to a longer time for impurity removal and a cumbersome process. When the sulfate is a potassium salt, it is suitable for all lithium ore, but the potassium salt is more expensive and the cost is higher.

　　③Sodium chloride pressure cooking method

　　The process of 　　 sodium chloride pressure cooking method is relatively simple, similar to the limestone method, and the amount of slag discharged is small. The production rate of lithium can reach 80%. Since the chlorine-containing system used is more corrosive to the equipment, the requirements on the equipment are relatively high.

　　In addition, there are processes such as sulfuric acid method and chlorinated roasting method to extract lithium from lepidolite. Lepidolite is a very complex substance. In general, how to improve the grade of lepidolite, reduce the amount of slag in the leaching process and separation process, and put the valuable elements into the liquid phase as much as possible during the leaching process and separate them economically , The process flow is as short as possible, and the corrosion problem of the equipment can be handled well at the same time is the issue that should be considered when selecting the lithium extraction process from lepidolite.

　　3. Conclusion

　　After decades of research on lithium extraction technology from lithium ore, my country's lithium extraction industry has made great technological achievements. For lithium ore, the production rate of lithium has been increased from 60% to more than 80%, and the amount of slag discharge and energy consumption have been further reduced, which has made a great contribution to the development of my country's lithium battery raw materials business. In addition, new processes such as extracting lithium from salt lakes are playing an irreplaceable role. In the future, my country’s technology for extracting lithium from minerals and salt lakes will be more and more perfect, improving the efficiency of comprehensive utilization of minerals, and transforming from a rough development model to fine processing. The efficient use of resources is for everyone in industry, mining, and earth. Responsibilities and obligations. Let us make the earth a better place!