Effect of Coating Mg(OH)<sub>2</sub> with Heterogeneous Deposition Method on Sticking during Fluidized Bed Reduction of Iron Ore

The aim is exploring a new MgO heterogeneous deposition coating method to increase the coating amount, and investigating its sticking prevention effect on the fluidized bed reduction of iron ore. The pure Fe2O3 or iron ore particles were coated with Mg(OH)2 using the heterogeneous deposition coating method. In order to restrain the homogeneous nucleation and promote the heterogeneous nucleation during precipitation, the NH4Cl–NH3·H2O pH buffer solution was employed to adjust the OH− concentration. The actual MgO coating amount on the particle surface has been improved to 3.8 wt%, and the sticking problem of Hualian iron ore during fluidized reduction can be avoided with the MgO coating amount of 0.91 wt%. This coating method achieved a satisfactory uniformity of the coating film, and there was nearly no uncoated part on the coated particle surface. The combination strength between the coating layer and particles' surface with different coating methods was investigated via a blowing system, and it was concluded that the solution and heterogeneous deposition coating methods could achieve a higher coating strength than the dry or slurry coating methods.