A process for production of highly metallised directly reduced iron (dri)with low sulphur content from waste or rejected iron ore slime and middling coal

摘要

The invention relates to a process for production of highly metallised directly reduced iron (DRI) with low sulphur content from waste or rejected iron ore slime and middling coal, comprising the steps of:- (i) grinding and screening waste iron ore fines (slimes) to an optimum size ranging between -70 to -200 mesh; (ii) pelletizing the ground and screened waste iron ore slime to obtain pellets of 12 to 20 mm diameter without or with addition of a binder; (iii) optimizing moisture content for making iron ore slime pellets by known method to achieved a green strength of the pellets ranging between 8 to 15N per pellet without/with addition of a binder for safe handling and further processing; (iv) grinding and screening waste middling coal in a size range of -70 to-200 mesh to use as a reducing agent during reduction; (v) grinding and screening desulphurisation agent (dolomite) to a size range of -70 to -200 mesh to be used during reduction; (vi) mixing the middling coal with desulphurizing agent (dolomite) in a weight ratio of 1: 0.05 to 1: 0.15; (vii) locating iron ore slime pellets in a static bed of middling coal for reduction in a weight ratio of 1: 0.3 to 1: 0.6, (viii) arranging a plurality of crucible containing said iron ore slime pellets in the bed of middling coal for reduction in a temperature range of 900 to 1100°C for a period of 1 to 6 hours; (ix) removing and cooling the crucibles containing the reduced iron ore slime pellets from said reduction temperature to a temperature between 500 to 600°C in the crucibles (reducing atmospheres) to avoid re-oxidation of the reduced iron ore slime pellets. (x) separating the reduced iron ore slime pellets from the residue of the bed of the middling coal.