Method for extracting lithium from bittern and preparing high-purity lithium concentrate

Abstract

The invention discloses a method for extracting lithium from bittern and preparing a high-purity lithium concentrate. The method is characterized by comprising the following steps: adding a 0.5-20kg / t magnetic lithium ion sieve into a bittern conveying pipeline, and adjusting the pH value to be higher than or equal to 5.0; separating the magnetic lithium ion sieve from the bittern by a magnetic separation system; feeding the magnetic lithium ion sieve into a desorption activation link; performing magnetic separation of the ion sieve and the desorption liquid again; feeding the magnetic lithium ion sieve into the raw bittern, and extracting lithium again; circulating the desorption liquid repeatedly until the lithium concentration is higher than or equal to 3g / l, and enabling the desorption liquid to pass through a nanofiltration membrane, wherein the filtered part of the nanofiltration membrane is the high-purity concentrate with purity of higher than or equal to 99%, and a lithium carbonate product is directly prepared; repeatedly circulating the intercepted part of the nanofiltration membrane by a nanofiltration link until the manganese-lithium ratio is greater than 2:1; adding sodium bicarbonate to prepare a manganese carbonate product; separating with PP cotton; and returning the lithium liquid to feed water to the nanofiltration membrane. In the invention, high-purity lithium concentrate can be prepared by use of the magnetic lithium ion sieve and by combining the magnetic separation and membrane separation technology; and in the process, the lithium concentration links such as solarization and reverse osmosis are not needed.

Description

technical field [0001] The invention belongs to the technical field of lithium extraction, and relates to a method for extracting lithium from brine and preparing high-purity lithium concentrate. Background technique [0002] Lithium is recognized as "the energy metal that promotes the progress of the world", and lithium batteries are widely used in home appliances such as mobile phones and computers. With the increase of human demand for clean energy and the growth of low-cost lithium salt production, lithium energy will profoundly affect human life. [0003] Lithium in nature is mainly abundant in pegmatite, salt lake brine, sea water, geothermal water and other deposits. The lithium resources that have been mined and utilized are mainly pegmatites and salt lakes, especially salt lake lithium resources. Lithium reserves in seawater are about 2.6×10 11 t is more than 10,000 times the total amount of terrestrial lithium resources. Therefore, the research on lithium extra...

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Problems solved by technology

These processes also have similar disadvantages: the granular lithium ion sieve is easily broken, and the operating efficiency of the adsorption bed is severely restricted, which is far from reaching the designed capacity.

[0012] If the above method is used to extract lithium from brine, since the concentration of lithium in brine is much higher than that in seawater, the pH of brine will drop during the lithium extraction process. If the acid-base environment of brine is not adjusted, the adsorption capacity of the ion sieve will be significantly inhibited; at the same time, The above-mentioned single magnetic separation process is difficult to realize the preparation of high-purity lithium products, and it is difficult to accurately control the concentration and purity of lithium in the eluent; at the same time, the above-mentioned method cannot control the dissolution loss of iron in the magnetic lithium-manganese spinel during operation, and cannot Recovery of dissolved manganese

[0013] In summary, both the lithium ion sieve technology and the lithium ion sieve extraction technology from brine in the prior art still need further breakthroughs.

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