白云鄂博铁精矿含碳球团直接还原实验研究

对于白云鄂博铁精矿进行了内配碳直接还原的研究,通过正交实验考察C/O、焙烧温度和H2/CO 3个因素对金属化率的影响.得出最优的实验方案:C/O为1.1,焙烧温度为950℃,H2/CO为3:2.在最优实验方案下,球团金属化率可达89.24%,还原度为91.96%.     

碱金属在白云鄂博铁精矿还原中的催化作用研究

利用失重法对碳的气化反应、CO气体以及碳还原白云鄂博铁精矿进行了实验,使用矿相、XRD分析了还原后样品的相组成与显微结构。研究结果表明：加入催化剂后,碳的气化反应速率和铁精矿还原速率提高,且K2CO3和Na2CO3的催化效果明显优于CaCO3的催化效果。催化剂的加入有助于碳的活性提高,加速了碳的气化反应,从而促进了白云鄂博铁精矿还原反应进行。     

利用白云鄂博铁精矿-铝土矿制备Fe-Al2O3复合材料的研究

以白云鄂博铁精矿和铝土矿为主要原料,以活性炭为还原剂,采用无压烧结法制备了 Fe-Al2O3复合材料.研究了不同烧结温度以及不同铝土矿添加量对相组成、微观结构、力学性能和耐腐蚀性的影响.结果表明:烧结温度以1 380℃为最佳,并发现铝土矿的添加量有利于材料力学性能的提升.其主要原因为铝土矿中含有TiO2,CaO,MgO等成分,在高温下形成液相,可以有效地促进复合材料的烧结.另外,液相也造成金属相周围热容不同,导致过冷度发生变化,进而影响金属相位错密度,低位错密度可以提高合金相的塑性变形能力.表明矿物中的杂质氧化物并不会影响复合材料的最终力学性能,反而具有一定的积极作用,为白云鄂博矿物的综合利用提供新的途径.     

白云鄂博铁精矿热物性与还原性实验研究

通过对白云鄂博铁精矿的研究,探讨其热物性参数及还原特性.在热平衡的基础上,根据一维稳态理论,测定了样品在不同质量比不同温度下的导热系数、体积比热及热扩散系数,回归得出了在高温状态下热物性参数与工作温度之间的关系方程;通过热重法及XRD分析相结合的方法分析其还原性,得出铁矿石与半焦混合物在整个还原反应中按阶梯式还原.     

白云鄂博铁精矿造块过程中含钾脉石与萤石的相互作用

通过对钾长石体系、钾长石-萤石体系及钾长石-萤石-CaO体系在内的含钾长石体系的高温焙烧过程的实验研究,确定了钾长石与萤石不同温度下相互作用的产物.研究结果表明,钾长石在1 090℃开始发生分解反应,生成白榴石(KAlSi2O6)和SiO2.钾长石中加入CaF2,900℃就已经发生钾长石的分解反应,1 060℃开始有硅铝酸盐的生成;钾长石中加入CaF2和CaO,体系中有硅铝酸盐生成,并在1 050℃开始生成枪晶石(3CaO· 2SiO2·CaF2),1 270℃有镁黄长石(2CaO·MgO·2SiO2)和铝黄长石(2CaO· Al2O3·SiO2);焙烧过程伴随有KF生成.     

铝硅比对白云鄂博铁精矿烧结液相流动性的影响

运用红外线微型烧结法对白云鄂博铁精矿烧结液相流动特性进行研究。通过在烧结原料中添加纯化学试剂研究不同Al2O3与SiO2含量之比对烧结液相流动性的影响。结果表明,Al2O3含量的增加虽然促进了烧结液相量的增多,但同时提高了液相的粘度,随着铝硅比的增加烧结试样的液相流动性降低。通过对试样气孔大小的对比,揭示了烧结过程中气孔形成与烧结矿液相流动特性的关系,粘度是控制气孔形成的重要因素。气孔的形成过程伴随着液相在气孔壁上的物理化学反应,气孔直径减小使烧结试样液相流动性变差。     

内配碳对双层球团还原膨胀率的影响

分别以磁铁矿粉和赤铁矿粉为原料制备双层结构的球团,并在球团内层配加焦粉,研究不同矿种及内层不同的配碳量对球团还原膨胀性能的影响。结果表明:在相同造球工艺和焙烧制度条件下,分别以磁铁矿粉和赤铁矿粉为原料制备的内层配碳双层球团的还原膨胀性能存在明显差异;以磁铁矿粉为原料的双层球团随着内层配碳量的增加,球团的还原膨胀率(RSI)先降低后升高,配碳量1.0%(质量分数,下同)时最低,RSI为7.98%;以赤铁矿粉为原料的双层球团随着内层配碳量的增加,还原膨胀率呈降低趋势,配碳量为1.5%时最低,RSI为9.52%。从球团的显微矿相结构看出:以磁铁矿粉为原料的双层球团内层配碳量超过1.0%,球团内出现磁铁矿晶体;以赤铁矿粉为原料的双层球团内层配碳量超过1.5%,球团内出现磁铁矿晶体,球团强度开始下降且还原膨胀率升高。     

农作物废弃物-铁精矿球团性能研究

采用农作物废弃物自制炭粉与铁精矿粉制备含碳球团,对含碳球团的造球特性进行了试验研究。结果表明：含碳球团的强度与造球物料的粒度、水分含量、膨润土加入量、焙烧还原温度等有关。物料粒度细、膨润土含量增加能提高球团的强度,适宜的碳氧比为1.0,水分和黏结剂配比分别为8.0%和6.5%;随着焙烧还原温度的提高,球团强度相应提高,当温度达到1 200 ℃时,随着金属铁快速还原与连晶的形成,球团落下强度为15次/个,抗压强度为1 650 N/个,能满足高炉入炉料的要求。     

矿壳内配碳球团试制金属化球团的实验室试验

矿壳球团在带式焙烧机上焙烧还原是一种投资少、成本低的生产高炉金属化球团的直接还原法。本文从理论上分析了矿煤球团用铁精矿（加添加剂）包壳所具有的优点，并介绍在实验室研究矿壳球团的配碳量、用铁精矿包壳时添加剂种类和用量、最高还原焙烧温度和升温速度、还原焙烧气氛等因数对金属化球团强度和金属化率的影响。     

Phase transformation and reduction kinetics during the hydrogen reduction of ilmenite concentrate

The reduction of ilmenite concentrate by hydrogen gas was investigated in the temperature range of 500 to 1200°C.The microstructure and phase transition of the reduction products were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),and optical microscopy(OM).It was found that the weight loss and iron metallization rate increased with the increase of reduction temperature and reaction time.The iron metallization rate could reach 87.5% when the sample was reduced at 1150°C for 80 min.The final phase constituents mainly consist of Fe,M 3 O 5 solid solution phase(M=Mg,Ti,and Fe),and few titanium oxide.Microstructure analysis shows that the surfaces of the reduction products have many holes and cracks and the reactions take place from the exterior of the grain to its interior.The kinetics of reduction indicates that the rate-controlling step is diffusion process control with the activation energy of 89 kJ·mol-1.     

Effect of dolomite on reduction swelling property of iron ore pellets

The effect of various dosages of dolomites on the reduction swelling property of iron ore pellets was studied. Experimental results show that the reduction swelling index(RSI) decreases from 13.35% to 4.0%, while the porosity of roasted pellets increases from 35% to 40% with increasing the dolomite dosage from 0 to 10.5%. Meanwhile, the content of magnesium ferrite with high melting temperature, as well as the stability of magnetite(Fe3 O4) in the roasted pellets, increases with increasing the magnesium oxide(MgO) content from dolomite. The reasons for the decrease of RSI rely on the absence of crystal transformation from Fe2 O3 to Fe3 O4, the increased porosity of roasted pellet, and the suppression of phase transition of 2CaO·SiO2 resulted from the incorporation of magnesium into calcium silicate.     

含铁尘泥高碱度内配碳球团自还原过程中脱硫和脱磷研究

在竖式碳管炉中进行含铁尘泥高碱度内配碳球团的还原试验,并通过改变温度、配碳比和碱度对含铁尘泥还原过程中的脱硫和脱磷进行研究。结果表明,高碱度内配碳球团在高温下快速还原制备金属铁粒的脱硫率高于97％,铁粒中硫含量最低达到0．007％,而脱磷率一般为25％～35％,最高达到38．52％。随着温度和配碳比的升高,铁粒的脱硫率和脱磷率均增加;而随着碱度的增加,铁粒的脱硫率和脱磷率均先增大后减小。     

Isothermal kinetics of the first stage reduction of magnetite cold bond pellets with carbon monoxide

The reduction of Fe₃O₄ to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heating-up process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe₃O₄ to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750°C, 800°C, 850°C and 900°C, respectively. The results showed that the reaction was controlled by chemical reaction below 800°C, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and Ginstling-Brounshtein diffusion as well. Project supported by the Nonferrous Metals Industrial Corporation of China Synopsis of the author Chen Qiyuan, professor, born in 1948. Major research fields: metallurgical thermodynamics and kinetics.