Fundamental Study on the Re-utilization of Waste Magnesia-Carbon Bricks as MgO Additive for Iron Ore Sintering

Waste magnesia-carbon bricks (MCB) exhibit great potential for being reutilized as MgO additive for iron ore sintering due to their main composition of high activity magnesia and extra carbon content. In this paper, the combustion characteristics of the carbon component of waste MCB were first studied by thermogravimetric, derivative thermogravimetric and differential scanning calorimetry thermal analysis. The influence of waste MCB utilization as MgO additive on the mineralization of sinter raw materials was also systematically investigated. The main conclusions are shown as below: (1) Compared with anthracite, the carbon component of waste MCB has relatively worse flammability and combustibility, and its combustion heat per unit mass is less; (2) As the MgO content of sinter increases from 2.0 to 3.0 wt%, the advantage of using waste MCB, compared with dolomite, as MgO additive in the crystallinity degree of sinter gradually appears; (3) At the MgO content of 3.0 wt%, the sinter using the combination of waste MCB and dolomite as MgO additive has higher content of calcium ferrite, and the distributions of main mineral compositions and pores are more uniform than the sinter totally using dolomite or waste MCB as MgO additive.