Lithium mica is a kind of mineral resource to obtain lithium resources, which has development value. At present, the common lithium extraction methods of lithium mica mainly include lime roasting, sulfuric acid roasting, sulfate roasting, chlorination roasting and pressure boiling.
The limestone sintering method for extracting lithium from mica is to grind the mica and limestone after mixing them (or after grinding the mica and limestone respectively), and then calcine them at 940~1050 ℃ (so that lithium minerals can be converted into water soluble compounds). After calcination, lithium minerals in them are extracted by normal temperature water leaching (lithium mica exists in the leaching solution as hydroxide).
Advantages: the lithium extraction process is simple, low cost, easy to obtain raw materials, low cost, and can be directly used to produce lithium carbonate.
Disadvantages: Due to the high calcination temperature, the process has high energy consumption, large material flow, large slag volume and low lithium recovery rate, which is easy to cause serious secondary pollution.
The method of extracting lithium from mica calcined with sulfuric acid calcines the quantitative lithium mica and sulfate at 150~300 ℃, and then the product is roasted at 800 ℃ for a second time. During the roasting process, the lithium in the lithium mica is converted into soluble lithium sulfate, and then the lithium resource is extracted under normal temperature water.
Advantages: the process is universal, can decompose various lithium-containing minerals, and aluminum in lithium mica will hardly be replaced during the process, with low impurity content, high leaching rate and simple process flow.
Disadvantages: In order to ensure the leaching rate of lithium, a large amount of potassium sulfate needs to be consumed, resulting in the high concentration of potassium sulfate and sodium sulfate in the solution and lithium sulfate easy to generate Li-Na-K or Li-K complex salt with low solubility, and the product is often contaminated by potassium, with high energy consumption, large amount of slag and difficult to use, high cost, expensive rubidium and cesium left in the slag can not be extracted, and there will be a lot of fluorine and sulfide waste gas volatilization in the high-temperature roasting process, Environmental pollution is relatively serious.
The method of extracting lithium from sulfate calcined mica is to use sulfuric acid to react with lithium mica, and hydrogen ion replaces lithium ion to generate soluble lithium sulfate, and then warm water immersion, purification of impurities, and addition of carbonate to make it react again to obtain lithium carbonate product.
Advantages: no need for high temperature roasting reduces energy consumption, and the amount of waste residue is small, and the lithium extraction efficiency is good.
Disadvantages: this method requires higher fineness of lepidolite, longer leaching reaction time, and large consumption of potassium salt.
Chlorination roasting for lithium extraction is to grind lithium mica and chlorides (sodium chloride and calcium chloride, etc.) in a certain proportion. After reaching a certain fineness, it is roasted at 900~950 ℃ to convert lithium minerals and other valuable metals into soluble chlorides, and then leach to obtain lithium solution.
Advantages: This method can improve the conversion rate of lithium, with high recovery rate, short reaction time and less waste residue.
Disadvantages: In the roasting process, due to the serious corrosion of chloride ions on instruments and equipment, the corrosion protection requirements are relatively high, and there are major problems in environmental protection.
The pressure boiling method for lithium extraction is to calcine the lithium mica for defluorination, and then wet grind it in a certain proportion in the presence of sodium carbonate. After it reaches the appropriate fineness, it reacts under the pressure of>200 ℃ and 0.2~2MPa. The sodium ion can effectively replace the lithium ion. The replaced lithium ions are leached in warm water. During the process, carbon dioxide needs to be injected into the water to convert lithium carbonate into soluble lithium bicarbonate. After solid-liquid separation, lithium bicarbonate solution is obtained, and lithium carbonate product is obtained after heating and decomposition.
Advantages: the process flow is simple, the material flow is small, the equipment corrosion is small, the energy consumption is low, and a large number of low-value by-products will not be generated.
Disadvantages: this process requires more carbon dioxide, more expensive sodium carbonate, higher requirements for equipment, strong corrosion resistance and lithium recovery rate.
The above is the introduction of the process methods of lithium extraction from different mica and their advantages and disadvantages. Each process has its own characteristics, but in the actual beneficiation plant, how to choose the process depends on the nature of the lithium mica ore. Therefore, the editor suggests that the beneficiation test should be carried out first, and the data should be used to customize the process, which has achieved a relatively ideal recovery rate.
