Abstract: The ores for selectin in the dressing plant of Longqiao Mining Co.，Ltd. is magnetite ores containing copper and sulfur，which was concentrated by the process of low intensity magnetic separation for iron separation and recovery of copper and sulfur from iron separation tailings. In order to ensuring the production capacity of the dressing plant maintaining at 3 million t/a，the test research and production transformation of wet preconcentration and waste disposal with gravity magnetic pull separator are carried out before grinding. The results showed that waste stone with yield of 6.68%，particle size of 12~2 mm， TFe content of 8.16%，magnetic iron content of 1.14%，copper content of 0.05%，and the sulfur content of 0.96% was obtained. The waste ore can be sold as high-quality building materials. The gravity magnetic pull separator was used for wet preconcentration before grinding，bringing about an annual benefit of 21.283 8 million yuan and ensuring the production scale of 3 million t/a for the mine.

Key words: preselection before grinding, building materials and stones, gravity magnetic pull separator