Method for extracting lithium salt by activating and pressure-leaching spodumene with slaked lime

Abstract

The invention discloses a method for extracting lithium salt by activating and pressure-leaching spodumene with slaked lime. The method comprises the following steps: (1) crystal form conversion; (2)activation and super-grinding; (3) pressure leaching; and (4) separation and purification. According to the method, the high-efficiency leaching of lithium in the spodumene is realized by adopting a slaked lime activation and pressure leaching process. Compared with a conventional process, the lithium salt leaching rate is high, the lithium salt leaching rate is 92% or more than 92%, a lithium salt product with the purity being more than 99.50% can be obtained, the Li2O content in leaching residue is less than or equal to 0.12%, the Si content in a leaching solution is less than 7mg / L, the calcium content is less than 20mg / L, the magnesium content is less than 4mg / L, the sodium content is less than 500mg / L, the potassium content is less than 500mg / L, and the iron content is less than 0.01mg / L. In addition, raw materials used in the invention are low in price and low in cost, the method has the advantages of small slag quantity production and good slag quality, the leaching residue can be recycled, and emission of waste water, waste gas and waste residue is avoided in the process.

Description

technical field [0001] The invention relates to the technical field of production of lithium salt extracted from spodumene in chemical metallurgy, in particular to a method for extracting lithium salt by using slaked lime to activate press-leached spodumene. Background technique [0002] Lithium has a series of excellent characteristics such as light weight, soft texture, large specific heat, and high negative potential. It is widely used in batteries, ceramics, glass, lubricants, refrigerants, nuclear industry, and optoelectronics. It is called "energy metal". " and "an important element that drives the world forward" are regarded as important strategic resources of spodumene by many countries. Spodumene (LiAlSi 2 o 6 ) is the main raw material for extracting lithium salt and preparing lithium metal, in which Li 2 The O content is 1-2%, and after enrichment by ore dressing, Li 2 O content can reach 5% to 7%. At present, in the production of spodumene in the production ...

AI Technical Summary

Problems solved by technology

Among them: (1) The limestone sintering method usually needs to add 3 to 3.5 times the amount of spodumene. This process has a low lithium recovery rate, a long process, high energy consumption, high cost of impurity removal in the leachate, and a large amount of tailings; (2) The sulfuric acid method (such as CN106966411A, CN 107640779A and CN102765734A, etc.) is currently the main method for processing spodumene at home and abroad. In this process, concentrated sulfuric acid is used as the leaching agent. During the leaching process, a large number of metal impurity ions enter the solution system, and later comparisons are required. Complicated impurity removal treatment, and the need to add high-priced sodium carbonate in the later stage, a large amount of low-value sodium sulfate is produced by-product, which increases the cost of the process; (3) sulfate method (such as patents CN107089674A and CN 104071811A, etc. ) is to sinter spodumene and sulfate (usually potassium sulfate) at a high temperature in a certain proportion. This process uses expensive potassium sulfate instead of sulfuric acid, which increases the entire production cost; (4) chlorination roasting method (such as patent CN106365180A , CN105271317A, etc.) use chlorinating agents (calcium chloride, potassium chloride or ammonium chloride, etc.) to roast spodumene to convert lithium into LiCl, but this process has serious corrosion of equipment, difficulty in collecting LiCl, and energy consumption High product quality; (5) The soda ash pressure cooking method (such as patent CN103183366A, etc.) uses sodium carbonate and spodumene to mix high-temperature pressure cooking, and the sodium and lithium undergo a displacement reaction to generate lithium carbonate. The reaction conditions are harsh, and there is currently no Realize practical application

[0004] Based on the above situation, there is no method with high recovery rate of lithium salt, short process, low cost, small slag production, and less impurity ions in the leachate.