The recovery of fine iron minerals from quartz and corundum mixtures usingselective magnetic coating

The recovery of hematite fines from quartz and corundum using selective mag netic coating was studied as a function of pH, particle size, magnetic coll oidal concentration, magnetic field strength and ratio of hematite:quartz. Synthetic mixtures assaying around 45-72% Fe2O3 was upgraded to 90-92% with recovery level of 90-96%. The optimum separation was observed at pH simila r to 7.2, colloidal concentration of 0.25 ml/g of hematite and a magnetic i ntensity of around 0.78 T. Electrophoretic mobility carried out on hematite , colloidal magnetite and quartz system showed a definite differences in th eir iso-electric points. The selectivity of coating was obtained by control ling the surface properties of the particle, the Zeta-potential being alter ed by pH adjustment and addition of sodium oleate. The separation of hemati te from corundum was achieved by using a dispersant such as sodium hexa met aphosphate. Microscopic, XRD and FTIR studies strongly suggested the coatin g of magnetite on hematite surfaces. Experiments were also conducted with h ematite, corundum and quartz mixture to simulate the condition of Indian ir on ore slimes. The results obtained are discussed in this paper. (C) 1999 E lsevier Science B.V. All rights reserved.