Recovery and Beneficiation of Talc Particles from the Gol-Gohar Iron Ore Processing Tailings

Talc is one of the main gangue minerals that coextract with magnetite in pit #1 of the Gol-Gohar iron ore mines. This valuable industrial mineral accompanies iron ore through comminution, pulp-making, and low-intensity magnetic separation, and is finally introduced into the tailing thickeners. Mineralogical and chemical analyses on a mixed sample obtained from the underflows of three thickeners of the company indicated that talc constitutes more than 30% (17% MgO) of the process waste. Wet low-intensity magnetic separation (WLIMS) experiments (1500 G) using 20% solid contents reduced total Fe from 12 to 6.7%, and increased the MgO grade from 17 to 18% in the non-magnetic product. Successive flotation experiments performed after WLIMS did not lead to an acceptable product. Individual rougher flotation tests using methyl isobutyl carbinol (MIBC) and sodium hexametaphosphate as frother and dispersant agents, respectively, improved the MgO content to more than 28%, and, after cleaner and recleaner stages, it was augmented to 32% while the Fe grade fell to 3%. To further reduce iron impurity, reductive leaching tests were carried out on the recleaner concentrate and optimized using the Box–Benken design. Oxalic acid and sodium dithionite were employed as reductants. A leaching temperature of 80°C, solid content of 7.5%, oxalic acid concentration of 1.0 M, and pH = 2 reduced the iron content to less than 1% in a 2-h leaching period. Considering the ~ 4 Mt/annum of the tailings disposed of by the Gol-Gohar iron ore processing plants, the production of ~ 300 Kt/annum of the talc concentrate is feasible.