Direct reduction and beneficiation of a refractory siderite lump

Abstract

Siderite is refractory to beneficiate and is directly used as burden for ironmaking because of its high loss of ignition (LOI) and decompositions of carbonate. In this paper, mineralogy of a siderite lump was studied, a process of coal-based direct reduction-magnetic separation of the siderite lump sample was proposed and process parameters have been optimised. It is shown that the final sponge iron powder, assaying 92·40% of Fe and 92·28% of metallisation degree, was manufactured with iron recovery of 96·60% under the following conditions: reducing siderite lump sample with 40·62% Fe and the particle size between 8 and 10 mm at 1050°C for 100 min and carbon to iron ratio of 2·3. Followed by wet grinding of reduced sample to 80% passing 0·037 mm and magnetic separation with Davis tube at 0·1 T magnetic field intensity. The author proposed an effective way of using siderite ores as burdens for electric arc furnace to produce superior special steel.