CaO－SiO_2－Al_2O_3－MgO－TiO_2渣系熔融还原过程中钛还原

在实验室条下，探讨了铁浴法熔融还原过程中，在ＣａＯ－ＳｉＯ＿２－Ａｌ＿２Ｏ＿３－ＭｇＯ－ＴｉＯ＿２渣系与碳饱和熔铁间钛的还原行为，以及渣中ＴｉＯ＿２含量、熔渣碱度（ＣａＯ／ＳｉＯ＿２）、还原温度、铁浴量等因素对钛还原的影响。     

CHARACTERIZATION OF PROPERTIES AND REDUCTION BEHAVIOR OF IRON ORES FOR APPLICATION IN SPONGE IRONMAKING

Studies on the chemical and physical properties, and the reduction behavior (in coal) of hematite iron ores procured from 10 different mines of Orissa, were undertaken to provide information for the iron and steel industries (sponge iron plants in particular). The majority of the iron ores were found to have high iron and low alumina and silica contents. All these iron ores were free from the deleterious elements (S, P, As, Pb, alkalies, etc.). The results indicated lower values of shatter and abrasion indices, and higher values of tumbler index in all the iron ore lumps except Serazuddin (previous) and Khanda Bandha OMC Ltd. For all the fired iron ore pellets, the degree of reduction in coal was more intense in the first 30 min, after which it became small. Slow heating led to higher degree of reduction in fired pellets than rapid heating. All the iron ores exhibited more than a 90% reduction in their fired pellets in 2-h time interval at a temperature of 900°C. Iron ore lumps showed a lower degree of reduction than the corresponding fired pellets.     

MECHANISMS OF REDUCTION OF IRON ORE/COAL AGGLOMERATES AND SCIENTIFIC ISSUES IN RHF OPERATIONS

Laboratory studies of chemical kinetics and heat transfer in the reduction of iron ore/carbon (coal) mixtures in various forms are reviewed. Therefore, the rate-limiting steps, which are of critical importance in process development, may be identified or suggested for a given set of conditions. Commercial operations using rotary hearth furnace (RHF) for the reduction of iron ore and waste oxide recycling by heating chemically self-sufficient agglomerates and related technical issues will be reviewed and discussed. The development of the next generation of processes based on ore/coal agglomerates, which would have very significant economical and environmental advantages, will be presented and discussed.     

Effect of CaCO3 on the Gaseous Reduction of Tin Oxide Under CO-CO2 Atmosphere

Calcite (CaCO₃), one of the main impurities, has an uncertain effect on the volatilization behavior of tin oxide in the tin-bearing iron ore concentrates during the selective reduction volatilization process. In this study, natural calcite powders were added into the tin-bearing iron ore concentrates to investigate tin volatilization behavior affected by CaCO₃ under different roasting temperature, CO content, and roasting time. In addition, the effect of CaCO₃ on the phase transformation of SnO₂ was determined using XRD, SEM-EDS combined with thermodynamics calculation. The results indicated that CaCO₃ had a significantly adverse effect on the Sn volatilization ratio, because Ca₂SnO₄ was easily formed under CO-CO₂ atmosphere. It was also found from the study that the generation of SnO_(s) was the most critical intermediate for promoting the formation of Ca₂SnO₄.     

铁矿石的价值评价与线性规划优化配料

针对攀钢烧结使用的原料品种越来越多,采用单烧方法计算了处种铁矿石单烧状态下的烧结矿品位、吨度价格,并以此作为评价铁矿石价值及矿石采购的重要依据。文章还利用基于目标规划模型对攀钢烧结原料进行优化配料,其原料成本明显低于经验配料法,具有显著的经济效益。     

Effect of mixing charge of highly reactive semicoke nut on the reaction of high Al2O3 ferrous burden in blast furnace

In order to improve the performance of blast furnace ironmaking when using the high Al₂O₃ iron ore, the technology of mixing charge of high reactive semicoke nut with ferrous burden was proposed and systematically investigated at laboratory scale in the present paper. The CO₂ gasification activation energy of semicoke ranged from 136.5 to 150.3?kJ?mol^?1, which was lower than that of the traditional coke. At the temperature of 1200°C, the reduction degree of ferrous burden increased a little with the addition of semicoke nut and the consumption ratio of semicoke was 14.0?wt-% under the simulated blast furnace ironmaking condition. The mixing charge of semicoke could obviously reduce the softening beginning temperature, increase the melting temperature and improve the permeability compared with the standard and traditional coke mixing charge samples. During the total softening and melting process, about 90?wt-% of the semicoke nut and 45?wt-% of the traditional coke nut were consumed, respectively. The experiment results indicated that the mixing charge of high reactive semicoke nut could obviously improve the performance of blast furnace ironmaking when using high Al₂O₃ ferrous burden and the semicoke was more effective than traditional coke.