CN-121976058-A - Magnesium removal method for lithium leaching solution with high magnesium content

Abstract

The invention discloses a magnesium removal method of a lithium leaching solution with high magnesium content, wherein the lithium leaching solution with high magnesium content is a lithium sulfate solution obtained by roasting, acidifying, leaching and impurity removal of spodumene ore; the magnesium removal method comprises the steps of introducing sodium hydroxide solution into the lithium leaching solution with high magnesium content, synchronously adding calcium hydroxide and magnesium hydroxide seed crystal, and carrying out solid-liquid separation by using a filtering device after the reaction is completed. The invention can obviously improve the efficiency of magnesium removal and filtration under the condition that the production line does not adjust the equipment process flow by optimizing the reaction raw materials and controlling and adjusting the process, thereby improving the processing yield and saving the production cost.

Inventors

• TAN JIE
• SUN YIXIN
• Wu Dingcheng

Assignees

• 湖南永杉锂业有限公司

Dates

Publication Date

20260505

Application Date

20251229

Claims (9)

1. 1. A magnesium removal method for a lithium leaching solution with high magnesium content is characterized in that the lithium leaching solution with high magnesium content is a lithium sulfate solution obtained by roasting, acidifying, leaching and removing impurities of spodumene ore, and comprises the following steps of introducing a sodium hydroxide solution into the lithium leaching solution with high magnesium content, synchronously adding calcium hydroxide and magnesium hydroxide seed crystals, and carrying out solid-liquid separation by using a filtering device after the reaction is completed, thus completing the magnesium removal of the lithium leaching solution with high magnesium content.
2. 2. The method for removing magnesium from a lithium leaching solution with high magnesium content according to claim 1, wherein the liquid-solid ratio of the lithium leaching solution with high magnesium content to calcium hydroxide is 0.4-0.6 m 3 /kg.
3. 3. The method for removing magnesium from a lithium leaching solution with high magnesium content according to claim 1, wherein the liquid-solid ratio of the lithium leaching solution with high magnesium content to the magnesium hydroxide seed crystal is 1.1-1.2 m 3 /kg.
4. 4. The method for removing magnesium from a lithium leaching solution having a high magnesium content according to claim 3, wherein a solid residue obtained by solid-liquid separation is added to the lithium leaching solution having a high magnesium content together with calcium hydroxide as a magnesium hydroxide seed crystal.
5. 5. The magnesium removal method for the lithium leaching solution with high magnesium content according to claim 1, wherein the mass concentration of a sodium hydroxide solution is 50%, the introducing amount is 0.2m 3 , the sodium hydroxide solution is added into the lithium leaching solution with high magnesium content in a spraying mode, and the introducing rate is 0.5-1 m 3 /h.
6. 6. The method for removing magnesium from a lithium leaching solution with high magnesium content according to any one of claims 1 to 5, wherein the reaction temperature is 80 to 85 ℃ and the reaction time is 30 to 60 minutes.
7. 7. The method for removing magnesium from a lithium leaching solution with high magnesium content according to any one of claims 1 to 5, wherein the pH of the reaction system is controlled to be 11 to 12 during the reaction.
8. 8. The method for removing magnesium from lithium leaching solution having a high magnesium content according to any one of claims 1 to 5, wherein the filtering device is a plate and frame filter press.
9. 9. The method for removing magnesium from a high magnesium content lithium leaching solution according to any one of claims 1 to 5, wherein the molar content of magnesium in the high magnesium content lithium leaching solution is 1000 to 1500ppm.

Description

Magnesium removal method for lithium leaching solution with high magnesium content Technical Field The invention relates to the field of lithium resource extraction, in particular to a method for removing impurities from lithium leaching solution. Background The battery grade lithium carbonate is taken as a part of the positive electrode material, participates in the charge-discharge reaction of the battery, stores and releases electric energy, and is a key material for manufacturing the lithium ion battery. Along with the rising of new energy markets of lithium batteries, the market demand of the new energy markets is also rapidly increased, and the technology of extracting lithium from ores in China for synthesizing lithium carbonate is dominant in the process and the productivity. The ore lithium extraction is mainly lithium sulfate solution obtained by roasting, acidifying, leaching and impurity removal of lithium ore. The spodumene raw ore is used as a main raw material for lithium battery production, is a pyroxene group mineral, is often associated with minerals such as quartz, albite, micro-inclined feldspar and the like, the lower the spodumene ratio is, the higher the miscellaneous ore is, the low-grade common inclined chlorite is mixed, the color is grass green to light olive, the magnesium content in the components is more, and the magnesium is dissolved into the leaching liquid along with inversion acidification. At present, a filter press is mainly used for solid-liquid separation after leaching magnesium removal in a lithium salt factory, and the filter press is mainly used for intercepting and filtering through filter cloth and slag cakes, so that magnesium hydroxide crystal particles are small in magnesium removal reaction, colloid and floccules are easy to generate, and meanwhile, the magnesium hydroxide has adsorptivity, the filtering speed can be greatly influenced, and the influence degree is more obvious along with the increase of the magnesium hydroxide proportion in magnesium removal slurry. Disclosure of Invention The invention provides a magnesium removal method of a lithium leaching solution with high magnesium content, which is used for solving the technical problem of low filtering speed of the prior art in the background technology. In order to solve the technical problems, the technical scheme provided by the invention is as follows: The magnesium removal method comprises the following steps of introducing a sodium hydroxide solution into the lithium leaching solution with high magnesium content, synchronously adding calcium hydroxide and magnesium hydroxide seed crystals, and carrying out solid-liquid separation by using a filtering device after the reaction is completed, thus completing the magnesium removal of the lithium leaching solution with high magnesium content. According to the invention, calcium hydroxide and sodium hydroxide are used as reaction raw materials for magnesium precipitation, the effect of calcium hydroxide on the high magnesium content leaching solution is good, calcium sulfate is formed by calcium hydroxide and sulfate radical in the leaching solution, and the calcium sulfate has larger particles and certain adsorptivity, so that on one hand, the large particle precipitation is provided, the compactness degree is reduced, the precipitation gap is increased, the colloid of magnesium hydroxide is not agglomerated like colloid, the colloid of magnesium hydroxide and coprecipitation of the colloid are attracted, the property of magnesium hydroxide and the like can be improved as filter aid, on the other hand, the proportion of magnesium hydroxide in filter residues can be reduced, the risk of colloid and floccule generation is reduced, and in addition, seed crystals are added to guide the transformation of precipitation products from amorphous colloid to easily-filtered particles, and the filtration speed is further improved. As a further preferable mode of the technical scheme, the liquid-solid ratio of the lithium leaching solution with high magnesium content to the calcium hydroxide is 0.4-0.6 m 3/kg. As a further preferable mode of the technical scheme, the liquid-solid ratio of the lithium leaching solution with high magnesium content to the magnesium hydroxide seed crystal is 1.1-1.2 m 3/kg. As a further preferable mode of the above technical scheme, the solid filter residue obtained by solid-liquid separation is added into the lithium leaching solution with high magnesium content together with calcium hydroxide as magnesium hydroxide seed crystal. The solid filter residue contains magnesium hydroxide and can be used as seed crystal, so that the production cost is reduced. The technical scheme is further preferable that the mass concentration of the sodium hydroxide solution is 50%, the introducing amount is 0.2m 3, the sodium hydroxide solution is added into the lithium leaching solution with high magnesium content in a spraying mode, and the introd