A novel co-extraction system and co-extraction method for extracting lithium from brine with high magnesium-to-lithium ratio

Abstract

The invention discloses a novel co-extraction system for extraction of lithium from high magnesium-lithium ratio bittern. The novel co-extraction system comprises an extraction agent and a co-extraction agent. The co-extraction agent is a mixture of one or more of potassium hexafluorophosphate, sodium hexafluorophosphate, magnesium hexafluorophosphate, calcium hexafluorophosphate, potassium fluoborate, sodium fluoborate, magnesium fluoborate and calcium fluoborate. The novel co-extraction method for extraction of lithium from high magnesium-lithium ratio bittern comprises extraction, back extraction, deposition for magnesium removal and deposition for lithium acquisition, wherein aiming at bittern with a magnesium-lithium ratio greater than 100, an elution process is used between extraction and back extraction. The novel co-extraction system has simple processes and a high lithium extraction rate, effectively reduces a magnesium-lithium ratio of bittern, has obvious advantages than the traditional ferric trichloride extraction system, can be used for extraction of lithium from salt lake bittern and is especially suitable for solving the problem of high difficulty of extraction of lithium from salt lake bittern with a high magnesium-lithium ratio.

Description

technical field [0001] The invention belongs to the field of chemical engineering, and relates to a technology for extracting lithium from salt lake brine, in particular to a novel co-extraction system and a co-extraction method for extracting lithium from brine with a high magnesium-to-lithium ratio. Background technique [0002] Lithium and its compounds are widely used in chemical industry, medicine, electronics and other industrial fields, so the global demand for lithium is also increasing at a rate of 8-12% per year, and the market price of lithium and lithium salts also maintains an upward trend. The world's salt lake lithium resources account for more than 70% of the total lithium resources, which will be the main direction for the development of lithium resources in the future. my country's salt lakes are rich in lithium resources, and most of the lithium-containing salt lakes in my country, such as Yiliping, Dongtai Jiner, Xitai Jiner, Chaerhan, Zabuye, and Dachaid...

AI Technical Summary

Problems solved by technology

①The research on the extraction system using tributyl phosphate as the extraction agent, inert solvent as the diluent and ferric chloride as the co-extraction agent is mostly studied. Patent CN87103431A uses this system to realize the extraction of lithium and obtain a higher recovery rate of lithium However, in this system, high-concentration (6-9mol / L) hydrochloric acid is used in the reverse-phase extraction process. On the one hand, the equipment is severely corroded, and general acid-resistant equipment cannot meet the requirements; the acid consumption is large, and the subsequent magnesium precipitation process increases. If the amount of alkali is reduced, it is impossible to realize the industrialization of lithium extraction. In addition, the use of ferric chloride as co-extraction agent needs to increase the concentration of Fe 3+ Recycling process, complex operation

②Patent CN101767804A adopts an extraction system using tributyl phosphate as extractant, ionic liquid as diluent and ferric chloride as co-extractant. This new extraction system has a better extraction effect on lithium, and the extraction process requires strong It is carried out in an acidic environment, and the acidity of the brine needs to be adjusted to a pH of 1 to 3. Since the extraction agent tributyl phosphate slowly degrades under acidic conditions, the extraction effect of the cycle decreases with the increase in the number of extraction stages; in addition, iron will also be extracted during the extraction process. , was finally back-extracted into the lithium-containing stripping solution, which not only lost iron, but also increased the difficulty of lithium precipitation; in addition, the synthesis process of ionic liquids is complicated and expensive, and the cost of lithium extraction in this system is relatively high; ③Patent CN103710549A adopts extraction Triisopropyl phosphate as the extraction agent, ionic liquid as the co-extraction agent, and kerosene as the diluent established a new salt lake lithium extraction system, which replaced the previous extraction system that used ferric chloride as the co-extraction agent, and The acidity of the lithium extraction process is reduced, and a good lithium extraction effect has been achieved. However, the ionic liquid used in this system also has the disadvantages of complex synthesis process and high price, resulting in an increase in the cost of lithium extraction; ④ patent CN102633284A uses tributyl phosphate as The extractant and perchlorate are used as the co-extractant system to extract high magnesium-lithium ratio salt lake brine, which avoids a series of problems caused by the addition of ferric chloride. However, this method has low stripping rate and lithium recovery rate In addition, because perchlorate ions cannot coexist with potassium ions, it is not applicable to lithium-containing salt lakes with generally high potassium content (relative to lithium) in China, so the application of this system has great limitations

[0004] After comparison, it is found that the above-mentioned patents and publications are not the same as the technical solutions of this patent application

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