Abstract: In order to effectively control the negative impact of the high lime alkali process on the separation of copper and sulfur, flotation tests in low alkali for separating copper and sulfur are made with CTP as the depressant of pyrite for a low grade porphyry-type copper-molybdenum ore of Inner Mongolia. The results show that under the grinding fineness of -200 mesh 65%, copper and molybdenum mixed concentrate with the Cu and Mo grade of 24.57% and 6.94% and the Cu and Mo recovery of 86.58% and 81.52% were obtained by the close-circuit process of one-roughing, three-scavenging, three-cleaning and middlings back to the flow sheet in order. Meanwhile,surveyed the effect of alkalinity and CTP to the floatation of Chalcopyrite and pyrite,the results show that:High alkali has a strong inhibit impact on pyrite, and inhibit chalcopyrite in a certain. CTP can inhibit pyrite well in low alkali condition, but less impact on chalcopyrite in flotation process. 

Key words: Copper-sulfur separation, Low alkalinity, Depressant, CTP