Abstract: Single sodium carboxymethyl cellulose (CMC) is used as inhibitor in cold decomposition-direct flotation process for production of potassium chloride from high calcium low potassium carnallite ore in Qinghai Golmud Salt Lake Region，but it has problems of water insoluble not fully inhibited，poor product quality，and low KCl recovery rate.Therefore，effects of combining inhibitor of CMC and W (a cationic poly amine reagent) and only CMC are compared in the cold decomposition-direct flotation process of Golmud Salt Lake high calcium and low potassium carnallite surface mines.Experimental results showed that，rough concentrate by the flotation process of one roughing and one scavenging has quality of average KCl content of 53.41%，average water insoluble substances content of 4.98%，average KCl recovery of 93.50%，average inhibition ratio of water insoluble substance of 73.46%; While using combined inhibitor CMC+W，rough concentrate has quality of average KCl content of 57.86%，average water insoluble substances content of 2.84%，average KCl recovery of 95.53%，average inhibition ratio of water insoluble substance of 85.82%.By comparison，the inhibition ratio of water insoluble substance of the latter was increased by 12.36 percent point，content and recovery of KCl of rough concentrate was increased by 4.45 and 2.03 percent point respectively，which indicated that the combined collector have higher inhibiting ability，and better selectivity as well.

Key words: Carnallite, Direct flotation, Combined inhibitor CMC+W, Inhibition ratio of water insoluble substance