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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