Method of combined extraction of magnesium and lithium in salt lake bittern

Abstract

A process for extracting Mg and Li from the brine of salt lake features that the ammonia and ammonium dicarbonate are used to implement two stages of magnesium deposition. For the first stage, the crystal seeds (5-10%) are added and the efficiency of magnesium deposition is controlled to 80-85%. For the second stage, the solid ammonium dicarbonate is added for reaction to obtain more than 98% of Mg extraction rate. The ammonium chloride in the mother liquid can be converted to ammonia for reuse. The lithium chloride solution enriched from the mother liquid can be used to prepare lithium carbonate. The extraction rate of Li is more than 95%.

Description

Technical field: [0001] The invention relates to the field of metallurgy, in particular to a method for jointly extracting magnesium and lithium from salt lake brine. Background technique: [0002] For salt lake brine with high concentration, especially high magnesium-lithium ratio, the separation and extraction of magnesium and lithium are very difficult. So far, there are few literature reports on this aspect. The extraction research of magnesium and lithium is carried out separately, so the production The cost is high and the overall benefit is poor. The extraction methods are now summarized as follows: [0003] (1) Lime milk precipitation method This method has high requirements on the activity and purity of lime, and the pH value control range of magnesium precipitation reaction is narrow, and it is not suitable for high-concentration brine, and the reaction product Mg(OH) 2 The particles are fine and difficult to filter, and the moisture content of the filter materia...

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Problems solved by technology

[0007] (3) The ion resin exchange method uses artificial resin to directly add Li to the brine to absorb Li. This method has a low utilization rate of the resin and loses the adsorption effect after only 2 to 3 times. It is uneconomical and large-scale production is still a problem;

[0008] (4) The organic solvent extraction method extracts lithium in the brine with tributyl phosphate, and there are two problems in this method, one is that the cost is high, and the other is that the organic solvent causes serious environmental pollution to the salt lake area;

[0009] (5) Xu's Lithium Extraction Method J. Hsu (Xu Jinghua), professor of Swiss Federal Institute of Technology and president of Tarim Scientific Mining and Petroleum Exploration Co. The old brine discharged from the Zhiyan Lake Potash Fertilizer Plant was tested indoors and in the field to extract lithium and achieved some success, but there are two problems in this method. 2 ·6H 2 O) crystallization output, the value is not high, the 2nd, in the process of evaporating and concentrating, though the lithium that is mixed in bischofolite is not high in relative content (0.98%), but absolute content is big, so the loss of lithium is big, and extraction rate not tall;

However, the reaction raw material brine and ammonia water need to be diluted, the volume of materials is large, the equipment capacity is low, the production cost is high, and the concentration of free ammonia in the reaction system is high, which is easy to cause environmental pollution.

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