Lithium Extraction, Impurity Removal, Calcium and Magnesium Removal from Spodumene Concentrate

Lithium element and its deeply processed products have a wide range of applications, and lithium carbonate is one of the lithium products. Currently, there are three main types that can be used to produce lithium carbonate. The first is salt lake brine, which accounts for about 68% of the total output value. The remaining are lithium mica and spodumene ore, which account for about 30% of the total output value.

At present, in most enterprises, the sulfuric acid method is used to produce lithium carbonate, which is also the main process method for producing lithium carbonate.

This process technology first goes through a rotary kiln during use, where spodumene is subjected to high-temperature conversion roasting to enable crystal transformation. The temperature inside the kiln needs to be maintained between 980-1200 degrees Celsius to ensure effective conversion of spodumene.

After the firing process of spodumene is completed, it is cooled and ball milled before being placed in an acidification kiln. The concentration of concentrated sulfuric acid in the acidification kiln needs to be maintained at around 98%, and the temperature inside the kiln needs to be kept at 250 degrees Celsius. After all the conditions inside the kiln meet the firing requirements, the acidification roasting process can be carried out. In this project, alkaline metals such as potassium, sodium, and lithium in the ore react with sulfuric acid in the kiln to produce a sulfate salt, in which the lithium element is leached in the form of lithium sulfate. Subsequently, it needs to be crushed, washed, dried, precipitated with soda ash, purified and purified to remove impurities, solid-liquid separated, and neutralized with limestone to produce lithium carbonate products.

The sulfate method involves roasting sulfate and spodumene together. Under high temperature roasting, spodumene gradually becomes loose, allowing potassium ions to replace the lithium element at the edge of the aluminosilicate in spodumene. Then, by adding water and leaching, a lithium sulfate solution can be obtained. Subsequently, lithium carbonate can be produced by precipitation with soda ash. The advantage of this process is to replace sulfuric acid with sulfate, thereby reducing equipment corrosion.

Among them, the leaching solution in the form of lithium sulfate also has the problem of impurity removal. The process developed by Haipu refers to the flow of the leaching solution of spodumene concentrate through a chelating cation exchange resin column, so as to adsorb the divalent or higher metal cations in the lithium containing solution. Subsequently, after evaporation, concentration, and pressure filtration, the lithium sulfate completion solution is obtained, and then the lithium precipitation operation is carried out.