Method for preparing high-purity magnesium oxalate, lithium carbonate and high-purity nanometer magnesia from salt lake brine of high magnesium-lithium ratio

Abstract

The invention discloses a method for preparing high-purity magnesium oxalate and lithium carbonate from salt lake brine of high magnesium-lithium ratio. The method comprises the following steps: 1) filtering the salt lake brine to remove suspended matters and solid impurities; 2) adding oxalic acid into the filtered salt lake brine; carrying out reaction for 30 to 180 min under the conditions that the temperature is 20 to 60 DEG C, the pH is 3 to 5, and the stirring speed is 150 to 500 rpm, so as to obtain brine of low magnesium-lithium ratio and magnesium oxalate precipitate; washing the magnesium oxalate precipitate with 40 to 60 DEG C hot water for 3 to 5 times; drying the washed magnesium oxalate precipitate at 80 to 102 DEG C for 60 to 120 min to obtain the high-purity magnesium oxalate of which the purity is larger than or equal to 98%; 3) adding an impurity removing agent into the brine of low magnesium-lithium ratio, so as to obtain refined brine; adding sodium carbonate into the refined brine to obtain lithium carbonate crystal; filtering the lithium carbonate crystal; carrying out washing and drying to obtain lithium carbonate. The magnesium oxalate prepared according to the method is high in purity.

Description

technical field [0001] The invention belongs to the field of comprehensive utilization of salt lake brine resources, and in particular relates to a method for preparing high-purity magnesium oxalate, lithium carbonate and high-purity nano-magnesium oxide from salt lake brine with a high magnesium-lithium ratio. Background technique [0002] As lithium energy, lithium alloys and lithium chemical products are widely used in communications, electric vehicles, electric power, aerospace, refrigeration, medicine and other industries, the demand for industrial lithium carbonate in the market is increasing. [0003] There are two main types of resources available for lithium extraction in industry, one is lithium-containing solid ore, and the other is various lithium-containing salt lakes. Among them, lithium in salt lakes accounts for about 70% of the world's lithium resource reserves. Alto and Silver Peak Lake in the United States are all brines with a low magnesium-lithium ratio...

AI Technical Summary

Problems solved by technology

[0012] At present, the main problem in my country's extraction of lithium-containing products from high-magnesium-lithium ratio salt lake brine is that the production cost is high, and it cannot compete with foreign products. The lithium extraction process is complex, lengthy, and energy-intensive. The composition of magnesium after the separation of magnesium and lithium is complex. Co-precipitation of magnesium ions and other metal ions in most processes cannot produce high-purity magnesium oxide or nano-magnesium oxide. The magnesium salt produced by the process is also a primary product. To be processed into high-purity or nano-scale magnesium products, it needs to go through multiple purification processes and consume a lot of chemicals and energy, so the processing cost is very high

[0013] It is not difficult to see from the technical summary of the above domestic and foreign studies on the separation of magnesium and lithium from salt lake brine and the enrichment of lithium. The large pollution to the environment is the main obstacle restricting the industrialization of lithium extraction from salt lake brine with high magnesium-lithium ratio in my country