Largevolume industrial solid waste of red mud is generated during alumina production by the Bayer process. Red mud features fine particles, severe argillization and complex mineral composition. Its main iron bearing minerals are hematite and goethite, accompanied by aluminium, silicon, calcium, titanium and other components. Iron minerals occur in finegrained disseminated form, and part of iron exists in other minerals via isomorphism, resulting in difficult separation. Direct stockpiling of red mud not only occupies extensive land, but also causes ecological risks due to alkali liquor leakage. Nevertheless, its abundant iron components are valuable for resource recovery. Boasting outstanding separation performance for fine grained weakly magnetic minerals, SLon vertical ring pulsating high gradient magnetic separators (SLon VPHGMS) have been industrially deployed in multiple domestic redmud iron recovery production lines and become key equipment for iron resource recovery from red mud.

Guangxi Jingxi Xinfa Environmental Technology Co., Ltd. is equipped with 4 sets of SLon-2000 VPHGMS and 4 sets of SLon-2500 VPHGMS. The raw red mud has a total iron grade of 23 %. Adopting the “one roughing  one cleaning” process, red mud iron concentrate of roughly 53 % total iron grade can be produced. In the same region, Guangxi Lvyuan Environmental Technology Co., Ltd. installs 2 SLon-2000, 3 SLon-2500 and 3 SLon-3500 VPHGMS units. It applies a flowsheet of one roughing plus one cleaning together with scavenging of cleaning tailings, achieving stable operating indexes: concentrate yield 20.87 %, iron grade 52.69 %, and iron recovery 35 %.