Abstract: A great deal of flotation salt was produced in a potash magnesium sulphate fertilizer manufacturing process,whose basic components were magnesium sulfate and sodium chloride.The content of magnesium was lower and the content of sodium was higher in the flotation salt.Aiming at lower magnesium and higher sodium of the flotation salt in potassium fertilizer production,a method for separation of sodium and enrichment of magnesium was used by means of step dissolution.After step dissolution,the yield of sodium (in solid phase) was 47.2%,and 98.3% of magnesium went into liquid phase. Magnesium product could be got by cooling crystallization.Magnesium yield was 56%.So sodium and magnesium were well separated under this condition. 

Key words: flotation salt, potash magnesium sulphate fertilizer, separation of sodium and magnesium