POWDERY IRON MATERIAL FOR USE AS FRICTION MATERIAL AND METHOD FOR REDUCTION THEREOF

摘要

A raw material for producing ferrite dust for friction elements and a method of producing reduced ferrite dust, capable of using, as the raw material, various collected sludge and dust which are by-products obtained at iron factories. The sludge has solid components consisting essentially of 35 to 50% total Fe, no more than 2% metallic Fe, 1.0 to 8.0% SiO2, 0.3 to 2.5% MgO, 1.0 to 6.0% CaO, 1.0 to 5.0% Al2O3, 20 to 40% fixed carbon, and 0.1 to 1.0% ZnO, said sludge having a grain size of 20 to 250 mesh, an apparent specific gravity of 1.2 to 2.0 g/cc, a real specific gravity of 3.3 to 4.3 g/cc, and a porosity of 40 to 65%. The collected dust consists essentially of 50 to 85% true Fe, 20 to 55% FeO, 30 to 55% Fe3O4, 2 to 12% CaO, 1 to 5% SiO2, 1 to 3% MgO, 1 to 3% MnO, and no more than 1% fixed carbon, 50 to 85% total Fe, 2 to 12% CaO, 1 to 5% SiO2, 1 to 3% MgO, 1-3% MnO, and no more than 1% fixed carbon. The sludge is treated under reduction conditions of a reduction gas charge rate of 8 to 20 Nl/min., a reduction temperature of 1,000 DEG to 1,200 DEG C., a reduction time of 20 to 60 minutes and a reduction gas-to-solid material ratio of 0.5 to 2.5 and then annealed at an annealing temperature of 650 DEG to 800 DEG C.