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 degrees C and the temperature can be reduced down to 500 degrees 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 x(c)/x(o) should be less than 1.5 for the need of reduction and carburization, and CaO and Al2O3 can spur the reduction of fayalite. On conditions that x(c)/x(o) is 1.2, metallization rate can be 77% when temperature is 1250 degrees C and only carbon is added, and metallization rate can be 74% when temperature is 1200 degrees C and only CaO is added. Moreover the addition of Al2O3 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 1250 degrees C, slag melting point of 1320 degrees C, and time of 30 min, the metallization rate can reach 88.43%.