Reduction process and zinc removal from composite briquettes composed of dust and sludge from a steel enterprise

In this study, composite briquettes were prepared using gravity dust and converter sludge as the main materials; these briquettes were subsequently reduced in a tube furnace at 1000-1300℃ for 5-30 min under a nitrogen atmosphere. The effects of reaction temperature, reaction time, and carbon content on the metallization and dezincification ratios of the composite briquettes were studied. The reduced com- posite briquettes were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and energy-dispersive spectroscopy （EDS）. The results show that the gravity dust and converter sludge are combined into the composite briquettes and a reasonable combination not only improves the performance of the composite briquettes, but also leads to the reduction with no or little reductant and flux. As the re- action temperature is increased and the reaction time is extended, the metallization and dezincification ratios of the composite briquettes in- crease gradually. When the composite briquettes are roasted at 1300℃ for 30 rain, the metallization ratio and dezineification ratio reaches 91.35% and 99.25%, respectively, indicating that most of the iron oxide is reduced and the zinc is almost completely removed. The carbon content is observed to exert a lesser effect on the reduction process; as the C/O molar ratio increases, the metallization and dezincification ra- tios first increase and then decrease.

Effect of Nickel on Formation Mechanisms of Silico-ferrite of Calcium and Aluminum(SFCA)

Under the pressures of both the de＇crease of high-grade high quality iron ore resources and the increase of raw material costs, the iron and steel enter＇prises in China turn to adopt iron ores which contain special elements such as nickel, manganese, etc. in the sintering blend. Anaiytica｜ reagents were used for sintering experiments, and the sinters were analyzed with X-ray diffraction, s6ailning electron microscopy and mineralogical microscopy to study the effect of nickel on the silico ferrite of calcium and aluminum （SF（＇A） bonding phase formation during sinte- ring. The results indicated that SFCA was divided into nickel containing and nickel-free areas due to the presence of nickel. The increasing content of nickel would greatly reduce the content of SFCA and promote the formation of calcium aluminum silicate. A great deal of Fe2 Oa participated in the crystal transition to Fe3 O3 , reducing the a mount of Fe2O2 involved in the formation of calcium ferrite. When the blending ratio of NiO, which is used to provide the nickel in the sintering process, is less than 3 % , the calcium ferrite is in substantially interleaving cot rosion with hematite and magnetite. Both the porosity and silicate glass phase content are low, which contributes to the sintering production.