Direct Reduction Experiment on Iron-Bearing Waste Slag

A lot of iron-bearing slags were produced, and whose grade is much more than that of industrial iron ore grade. Chemical analysis and phase identification shows that the iron-bearing slag is amorphous, has fayalite main phase, iron grade is 36. 10%, and is difficult to recover iron from the slag. Thermodynamic calculation indicates that CO cannot reduce fayalite at high temperature and carbon direct reduction can be effective. Moreover, the reaction begins at 770 °C and the temperature can be reduced down to 500 °C when CaO is added. On this basis, a method is put forward to making direct enrichment of iron by taking carbon contained pellets to realize the rapid reduction of fayalite, and the direct reduction process were studied in this paper. Experiments show that Xc/xo should be less than 1. 5 for the need of reduction and carburization, and CaO and A12O3 can spur the reduction of fayalite. On conditions that xc/xo is 1. 2, metallization rate can be 77% when temperature is 1 250 °C and only carbon is added, and metallization rate can be 74% when temperature is 1200 °C and only CaO is added. Moreover the addition of A12O3 can get a higher metallization rate (10% or so) than usual as R is between 0. 4 and 1. 0. Under the optimized condition of R equals to 0. 6, temperature of 1 250 °C, slag melting point of 1 320 °C, and time of 30 min, the metallization rate can reach 88. 43%.