Lithium chloride liquid purification method and lithium chloride liquid purification equipment

Abstract

The invention discloses a lithium chloride liquid purification method. The method includes steps: 1) converting sulfate radical ions, calcium ions, magnesium ions and iron ions in lithium chloride liquid into precipitates, and separating the precipitates out to obtain first liquid; 2) allowing the first liquid to pass through first filter equipment being 0.1-50micron in filter particle size to form first filtrate after the first liquid passes through a filter structure of the first filter equipment, wherein the calcium ion concentration of the first filtrate is smaller than or equal to 35ppm, and the magnesium ion concentration of the first filtrate is smaller than or equal to 35ppm; 3) adjusting pH of the first filtrate to 9-12, and allowing the first filtrate to pass through second filter equipment to form clear lithium chloride liquid after the first filtrate passes through a filter medium of the second filter equipment, wherein the second filter equipment is larger than or equal to 99.95% in interception rate of substances with molecular weights larger than or equal to 300, the filter medium of the second filter equipment is a membrane with membrane flux larger than or equal to 15L / m<2>.h, the recovery rate of the clear lithium chloride liquid is larger than or equal to 70%, the flow rate is larger than or equal to 10L / min, the calcium ion concentration of the clear lithium chloride liquid is smaller than or equal to 10ppm, the magnesium ion concentration of the clear lithium chloride liquid is smaller than or equal to 10ppm, and the Li2O loss rate is smaller than or equal to 8.5%.

Description

technical field [0001] The invention relates to the technical field of lithium chloride production, in particular to a method and equipment for purifying lithium chloride feed liquid. Background technique [0002] High-purity lithium chloride is an important strategic resource substance, widely used in air conditioning, flux, desiccant, chemical reagents, fireworks, dry batteries and metal lithium, etc. It is indispensable for modern high-tech products important raw material. For example, in the preparation of lithium metal, high-purity lithium chloride is mainly obtained by molten salt electrolysis as a raw material. Due to the presence of impurities such as calcium, iron, magnesium and sulfate in industrial lithium chloride, these Impurities will enter the product lithium metal or have a detrimental effect on the electrolysis process, so obtaining high-purity lithium chloride is critical. [0003] At present, the preparation of lithium chloride mainly uses industrial lit...

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Problems solved by technology

Conventional chemical and chemical purification methods such as co-precipitation method, fractional crystallization method, solvent extraction method, ion exchange method, etc., the purification of lithium chloride is not enough to remove impurities such as calcium, iron, magnesium and sulfate radicals, or even To a certain extent, it has a good removal rate for impurities in the lithium chloride feed liquid, but due to the fluctuation of water quality, the impurities in the medicament itself, and the characteristics of the chemical reaction itself, the feed liquid after lithium chloride purification often cannot reach Purity requirements

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