Roasted iron ore pellets with controlled macroporosity - which raises softening point and improves degree of redn. obtd.

摘要

Roasted iron ore pellets which are porous contain macropores of 0.1-3.0 mm. dia. The macropores constitute max. 25% of the total porosity, pref. 5-25%, and esp. 15-25% of the total porosity. The raw material used for the pellets pref. contain by wt. up to 3% MgO as a flux. Pref. the raw materials are crushed and contain max. 4% carbonaceous material, size 0.1-3 mm. dia., with max. 3% MgO, 0.1-3 mm. dia. The mixt. is then pelletised and roasted, so that max. 25% of the pores are macropores with dia. 0.1-3 mm. Used for mfr. of pellets used in a blast furnace to make crude iron. The intentional macroporosity results in a consistently high and uniform degree of redn. because the redn. gas can penetrate the macropores. The pellets also have a high m. pt. so they flow smoothly down the blast furnace without sticking; and the macropores facilitate the redn. of dusts obtd. in purifying waste gases to avoid environmental pollution.