Production of Reduced Pellets from Lignite Semicoke

摘要

The possibility of using iron-ore concentrates from the Bachkar field and lignite semicoke from the Talovskoye field (Tomsk region) to obtain highly reduced pellets is considered. The high tar yield in the heat treatment of lignite hinders its use as a reducing agent in industrial processes and necessitates its conver sion to semicoke. Analysis of the properties of carbon-based reducing agents indicates that lignite semicoke is more reactive than metallurgical coke and has a more developed porous structure. Semicoking of the lignite is optimal at ~600℃ , with roasting for about 40 min. The tar is completely removed, and the residual quantity of volatiles is sufficient for reduction by carbon in a hydrogen-bearing atmosphere. The production of iron-ore pellets from lignite semicoke is studied; the conditions of reductive roasting and the characteristics of the process are determined. At 950℃ , 90-92% reduction is achieved after around 1 h. A production system for reduced pellets based on iron-ore concentrates and lignite semicoke in shaft furnaces is developed. The gases formed in the reduction of oxides (CO + H_2 + H_2O) provide the heat required for the process.