Arsenopyrite removal from pyrite concentrate using pulsating high gradient magnetic separation

Pyrite concentrate has been the mineral resource for sulfur acid production in China, and arsenopyrite as one of the arsenic-containing minerals, was usually found in the pyrite ores, resulting in the serious environmental problems in the production process. Pulsating high gradient magnetic separation (PHGMS) was innovatively used to upgrade an unqualified pyrite concentrate with arsenic content reaching as high as 3.49%. The effects of five key operating parameters, i.e., feed weight, matrix, magnetic induction, pulsating frequency and grinding fineness, on the pilot-scale PHGMS performance were investigated. The PHGMS significantly reduced the arsenic content in the concentrate, and improved the sulfur grade of the concentrate at a high recovery. When the parameters were all optimized, an upgraded pyrite concentrate was produced through a roughing and re-concentrating pilot-scale PHGMS process, which was further confirmed in a full-scale process, producing a pyrite concentrate assaying 27.14% sulfur with 83.47% recovery and reducing the arsenic content down to 0.43% in the concentrate. It was thus concluded that the PHGMS method has provided an effective way in removing arsenopyrite from pyrite ores.