Method for combined extracting boron, magnesium and lithium from salt lake bittern

Abstract

The invention relates to salt lake resource developing and comprehensive utilization. It uses boron, magnesium and lithium bittern as raw material, adopting combination distilling technology to make boric acid, magnesium hydroxide, lithium carbonate, and ammonium chloride. The recycling ratio of boron, magnesium and lithium reach 87%, 95%, and 92%. It has the advantages of simple technology, little device investment, high utilization coefficient of resource, high yield, good product quality, low producing cost and no pollution.

Description

technical field [0001] The present invention relates to the development and comprehensive utilization of salt lake resources, in particular to a kind of salt lake brine containing boron, magnesium, and lithium as raw materials, and adopts a combined separation and extraction process to prepare boric acid, magnesium hydroxide, lithium carbonate, and ammonium chloride respectively. A method for jointly extracting boron, magnesium and lithium from salt lake brine. Background technique [0002] my country is a country rich in salt lake resources. According to incomplete statistics, the area is greater than 1km 2 There are 813 inland salt lakes in China. Among them, there are 234 in Tibet, 71 in Qinghai, 375 in Inner Mongolia, and the rest are scattered in Jilin, Hebei, Shaanxi, Ningxia, Gansu and other provinces. Among the salt lake resources, potassium, sodium, magnesium, lithium, and boron are the most abundant resources. The reserves of potassium, sodium, magnesium, lithiu...

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Problems solved by technology

The feature of this method is that no additional chemical reagents are needed for the separation of magnesium and lithium, but the energy consumption is high, the recovery rate of lithium is low, and the lithium carbonate produced contains many impurities; the magnesium hydroxide obtained by the hydration of magnesium oxide has very poor filtration and washing performance. Moreover, it contains a large amount of boron; it should be pointed out that 100 tons of low-concentration hydrochloric acid should be produced as a by-product for every 1 ton of lithium carbonate produced. If the place of origin cannot digest it, it will be very difficult to store and transport; (2) Carbonate precipitation method (2) Industrial soda ash Na 2 CO 3 When added to brine, the following reaction occurs: Na 2 CO 3 +2Li + -Li 2 CO 3 ↓+2Na + This method is used to extract lithium salt (Li 2 CO 3 ), this method is not suitable for the brine with high ratio of magnesium to lithium, because it is very uneconomical to remove magnesium with a large amount of soda ash before extracting lithium; (3) the adsorption method utilizes artificial resin to directly add in the brine to absorb Li + , the resin utilization rate of this method is low, and the adsorption effect is lost after only 2 to 3 times, so this method is not economical, and large-scale production is still a problem; (4) organic solvent extraction method uses tributyl phosphate to extract the Lithium, there are two problems in this method, one is high cost, and the other is that organic solvents cause serious environmental pollution to the salt lake area; President J.Hsu (Xu Jinghua) used the "evaporation pump principle" and the in-situ "chemical reaction pool method" to carry out indoor and field lithium extraction experiments on the old brine discharged from the Qinghai Qerhan Salt Lake Potash Plant in my country and achieved some success. There are also two problems, one is magnesium bischofite (MgCl 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 (5) Membrane separation method uses membranes made of special materials to separate magnesium and lithium, and then use sodium carbonate and sodium hydroxide to remove magnesium in depth, and then use sodium carbonate to convert lithium carbonate. The main problem is that the membrane used to separate magnesium and lithium needs to be imported from abroad, and the service life of the membrane needs to be tested in production practice. On the other hand, the power consumption is also very high.

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