Method for refining lithium from salt lake brine with high magnesium-lithium ratio

Abstract

The invention discloses a method for refining lithium from salt lake brine with a high magnesium-lithium ratio. The method comprises the following steps: 1) removing sulfate radicals from brine from which sodium and potassium are extracted, evaporating the brine to obtain lithium-rich and boron-rich brine; 2) extracting boron from the lithium-rich and boron-rich brine to obtain boric acid and lithium-rich brine; 3) separating the lithium-rich brine by using a nanofiltration membrane to obtain primary concentrated water and primary produced water; 4) through reverse osmosis, separating the primary produced water to obtain secondary produced water and fresh water; 5) removing magnesium from the secondary produced water, and evaporating the secondary produced water to obtain refined lithium-rich brine. The method is simple in technological process; by the method, the energy consumption is greatly reduced, salt lake brine resources are fully used, and the recycling rate of the lithium ions is greatly improved; influence of the boron on lithium carbonate or other lithium salt products is avoided, thus the quality and the competitiveness of products are greatly improved.

Description

technical field [0001] The invention belongs to the field of salt lake chemistry, and in particular relates to a method for refining lithium from salt lake brine with a high magnesium-lithium ratio. Background technique [0002] Lithium is the lightest metal in the world. Due to its special properties, lithium and its compounds have extensive and special uses, and are known as "energy metals" and "metals that drive the world forward". It plays an extremely important role in the energy industry, aerospace industry, metal smelting and manufacturing industry, refrigeration, ceramics, glass and other industries. At present, the global demand for lithium products is very urgent, and the demand for lithium is increasing rapidly year by year. [0003] The largest resource of lithium in the world is lithium ore, mainly including spodumene, lepidolite, lithium petalite, spodumene and eucryptite. The traditional lithium mining industry mainly extracts lithium products through strong...

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Problems solved by technology

[0026] Chinese patent applications with application numbers 03108088.X, 201010295933.X, and 201310035015.7 have disclosed the use of nanofiltration membranes to separate magnesium and lithium, but the brine conditions disclosed in the patent application with application number 03108088.X are too broad and do not take into account equipment Applicability has little practical significance; the patent application with the application number 201010295933.X has partially improved it, but recycling the concentrated water obtained by nanofiltration in the nanofiltration membrane system will lead to the magnesium-lithium ratio of the nanofiltration produced water Greatly increased, increasing the number of stages of the nanofiltration membrane system; in addition, this application did not consider the influence of other ions in the actual multi-component brine on the separation of magnesium and lithium during the separation of nanofiltration membranes, and did not consider the impact of membrane performance on magnesium and lithium. The influence of the separation effect has certain limitations in practical applications; the Chinese patent application number 201310035015.7 has published a detailed description of the separation of magnesium and lithium by nanofiltration membranes, and has carried out actual brine tests, and the separation of magnesium and lithium has good results , but the boron element inevitably shunts in the process of passing through the nanofiltration membrane, and the boron permeability reaches 20%. If it is not removed, it will have a great impact on the quality of the final lithium carbonate or other lithium salt products. impact, greatly reducing the quality of the product

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