System method for extracting lithium-containing brine from lepidolite and manufacturing lithium salt

Abstract

The invention discloses a system method for extracting lithium-containing brine from lepidolite and manufacturing lithium salt. The system method comprises the following steps: material mixing, roasting, brine preparation, lithium salt preparation and comprehensive utilization of tailing slag. According to the invention, sulfuric acid double salt and sulfuric acid (selected) are used as auxiliarymaterials to be mixed with the lepidolite for reaction; the system method is applicable to extraction of lithium in high-content and low-content lepidolite; good selectivity is achieved during extraction; the extraction rate of lithium is 95.5%-97.5%; and the extraction rates of K, Rb and Cs are smaller than 30%; the obtained brine is neutral and can be used for directly preparing lithium hydroxide monohydrate, lithium chloride or lithium carbonate, and the total yield of lithium is more than 92%; the process is high in flexibility, can produce single-variety lithium salt, and can jointly produce two or more varieties of lithium salt; and fluorine in the lepidolite can be separated and recovered, so the additional value is increased, and the lithium extraction tailing slag can be comprehensively utilized. The system method provided by the invention has the following advantages: the whole process is short in flow, low in cost and friendly to the environment; and the system method has good economic benefits and social benefits and good industrial application values.

Description

technical field [0001] The invention relates to a systematic method for extracting lithium-containing brine from lepidolite and producing lithium salt, which is suitable for extracting lithium-containing brine from lepidolite and producing lithium salt (lithium hydroxide monohydrate, lithium chloride, lithium carbonate), It belongs to the technical field of rare metal extraction. Background technique [0002] Lithium salts currently produced on a large scale include lithium carbonate, lithium hydroxide monohydrate, lithium chloride, lithium fluoride, lithium sulfide, lithium dihydrogen phosphate, and lithium hexafluorophosphate. Among them, the production scale of lithium carbonate, lithium hydroxide monohydrate and lithium chloride ranks the top three, and the three can be transformed into each other, and they are also the basic materials for the preparation of other lithium salts. [0003] Lithium carbonate is widely used in glass, ceramics, lubricants, medicine and other...

AI Technical Summary

Problems solved by technology

The main disadvantages of the sulfuric acid method are: ① a large amount of sulfuric acid is required during leaching, and a large amount of aluminum elements are leached, resulting in a large amount of neutralization slag, a large amount of solid waste and difficult to handle; ② long leaching time, more than 8 hours, energy consumption High, low production efficiency; ③ During leaching, hydrofluoric acid volatilizes, which is extremely corrosive to equipment and unfriendly to the environment; ④ High impurities, product quality is average, especially residual potassium, rubidium and cesium in brine, which will be quantified brought into the product, resulting in a decline in product quality

This process needs to add a large amount of sodium sulfate, and the selectivity is not good; a single sodium sulfate has a low melting point, and it is easy to form a low-eutectic molten mass with mica, resulting in wall agglomeration during roasting, which increases the difficulty of subsequent processing and is not conducive to industrial production. ; more suitable for high-grade lepidolite, with limited scope of application; there is no good comprehensive utilization method for lithium extraction tailings slag and fluorine; this technology does not provide an effective technical route for subsequent treatment of high-sodium lithium-containing brine

[0010] The advantage of the sulfate method is that the roasting conversion rate in the early stage is high, and the disadvantage is that a large amount of sodium sulfate, potassium sulfate and lithium sulfate are easily generated in the solution to form Li （2-X-Y） Na X K Y SO 4 Type double salt, resulting in lower yield and efficiency in the later stage; the price of potassium sulfate is more than 6 times higher than that of sodium sulfate, so in the design, it should be as possible to adopt the technical route with wide application range, good reaction selectivity and lower cost

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