白云鄂博铁矿球团富氢还原动力学研究

针对气固直接还原工艺中存在着气体利用率低和还原供热不足等问题,利用恒温热重分析(TG)法,研究了氢/碳比率对白云鄂博铁精矿还原速度的影响。结果表明,在还原试验开始后40 min内,还原速率随wH2/wCO比增加而增大,使得Fe2O3→Fe3O4反应时间缩短。基于气相内扩散和界面反应的球团还原速度方程均能较好地处理本研究的数据,得到了反应速度常数与wH2/wCO的关系为:k界面=-0.1975+0.3 575wH2/wCO,k扩散=0.171 01+0.269 7wH2/wCO。根据Arrhenius方程计算出界面反应和气相内扩散活化能分别为26 k J/mol和44 k J/mol,因此本研究条件下限制性环节为气体内扩散控制。     

碱度对白云鄂博铁精矿压团矿抗压强度的影响

发展熔剂球团矿是当前炼铁原料工艺技术发展的方向和热点之一,球团矿的碱度不同,其理化性质及冶金性能也不同。通过分析不同碱度的白云鄂博铁精矿压团矿矿相结构的变化规律,探究碱度对白云鄂博铁精矿压团矿抗压强度的影响规律。结果表明,随着碱度的升高,压团矿的抗压强度先增加后降低,液相量的增加使得孔隙率降低,压团强度升高,但过多的液相会破坏赤铁矿的整体性结构,渣相强度低于赤铁矿强度,压团的强度逐渐降低。     

铁精矿流态化预还原过程的研究

用流化床热模型对几种铁精矿进行了流化还原过程的试验,结果指出,在一定范围内,提高还原温度和流化床床层线速可以改善流化还原过程.探讨了影响流化床粘结失流的主要因素.     

膨润土对白云鄂博铁精矿球团矿生球及成品球强度影响

膨润土主要作为黏结剂用于球团矿生产过程以提高球团矿强度,不同膨润土对球团矿生球及成品球强度有不同的影响.在测定两种膨润土的理化性能和化学成分基础上,将其与白云鄂博铁精矿混合造球,试验测定生球及焙烧后的成品球强度.分析可知,膨润土中胶质价含量越高,白云鄂博铁精矿球团矿生球强度越大;膨润土的吸水率高有利于提高球团矿生球抗压...     

包钢烧结提高白云鄂博铁精矿比例的生产实践

文章在包钢现有原料条件及工艺条件下,对生产用各种铁料的性能进行了研究,通过优化配矿以及复合造块技术的应用,使烧结白云鄂博铁矿比例提高至76%以上,烧结精粉率也提高至76%以上,其中超细精矿比例接近50%,解决了包钢白云鄂博特殊矿难烧的问题。     

白云鄂博铁球团矿异常还原膨胀的机理

通过对比白云鄂博铁矿、精矿及还原前后球团矿的显微结构,对白云鄂博球团矿异常还原膨胀的机理进行研究。研究结果表明,球团矿气孔中挥发分的爆发扩大了基体裂块间的孔隙,加快了还原气体的扩散,增加了反应面积,使还原速度加快,从而导致了球团矿恶性膨胀。白云鄂博球团矿的“挥发分膨胀理论”是一种全新的理论,对抑制白云鄂博球团矿的恶性膨胀具有重要指导意义。     

直接还原-渣金熔分法富集白云鄂博主东矿铁精矿粉中的稀土

对于白云鄂博主东矿铁精矿粉,采用直接还原-渣金熔分法将其中的稀土富集在脉石形成的熔渣中,测定了熔渣的化学成分、结构、熔化温度,考察了熔渣的微观形貌及其组成,探明了熔渣中稀土的富集状况。研究结果表明,海绵铁渣金熔分后脉石形成的熔渣的熔化温度为1350℃,熔渣中稀土元素显著富集,且稀土以氧化物形态优先结晶析出,稀土富集区中稀土氧化物的含量在60%左右。     

白云鄂博西矿含铁岩石选矿试验研究

白云鄂博西矿是一座大型露天矿,其中在露天开采境界内有大量的含铁岩石,如何利用含铁岩石,使其变废为宝,成为企业增加资源利用率的关键。文章对白云鄂博西矿含铁岩石进行了系统的选矿实验研究,利用科学的选矿方法,在实验室完成了含铁岩石综合利用的理论研究工作,为下一步选厂设计和工业应用提供重要依据。     

白云鄂博矿床成因研究

利用综合地质研究手段,通过地表地质调查、地质统计学、元素空间富集规律、最新深部钻孔资料及流体包裹体的研究,提出了白云鄂博铁、稀土、铌矿床成因认识,认为白云鄂博铁、稀土、铌矿是火成碳酸岩浆成因,伴随后期多期热液交代活动。该成果为白云鄂博建立找矿模式、进行成矿预测及评价、准确寻找资源靶区提供了重要依据。     

烧结去除白云鄂博氧化矿强磁精矿试验研究

文章针对选矿过程中含铁硅酸盐矿物与赤铁矿物难分离的特点,且含铁硅酸盐矿物集中存在于白云鄂博铁精矿的氧化强磁精矿中.属于有害杂质含量高、难还原的部分,进行自产混精去除氧化强磁精矿后的烧结试验研究.试验结果表明:可以改善烧结性能,提高烧结矿品位,降低烧结矿的有害杂质含量,有利于改善烧结矿的冶金性能.     

钛精矿流态化预氧化氢还原试验研究

钛精矿流态化氢气还原生产高钛渣技术不仅原料选择范围广、能耗低,而且可实现清洁生产。在冷态试验基础上对钛精矿在高温下先氧化再还原试验进行了探索,研究了温度、还原时间、p(N2)/p(H2)和粒度对金属Fe还原率的影响。试验结果表明:800～950℃,随着还原温度的升高,Fe的金属化率有较明显的增加;在同一温度下,Fe的金属化率随时间延长先快速增加而后趋缓;随着粒径的减小,钛精矿的Fe还原率提高较明显;氢气的浓度对钛精矿还原影响至关重要,随着氢气浓度的增加,还原率有着明显的提高。     

Reduction Kinetics of Fine Iron Ore Powder in Mixtures of H2-N2 and H2-H2O-N2 of Fluidized Bed

Reduction kinetics of fine iron ore powder in different gas mixtures were investigated in high-temperature fluidized bed at a scale of kilograms.Influence of processing parameters,such as particle size,gas flow velocity,height of charge,temperature,compositions of gas mixture,and percentage of inert components,on reduction kinetics was experimentally determined under the condition of fluidization.The equations for calculating instantaneous and average oxidation rates were deduced.It was found that an increasing H2 O percentage in the gas mixture could obviously decrease the reduction rate because the equilibrium partial pressure of H2 decreased with increasing content of H2 O in the gas mixture and then the driving force of reduction reaction was reduced.When the H2 content was high,the apparent reaction rate was so rapid when the average size of iron ore fines was less than 1mm that the reaction temperature can be as low as 750 ℃;when the average size of iron ore fines was more than 1mm,a high reaction temperature of 800 ℃ was required.In addition,it was also found that the content of H2 O should be less than 10%for efficient reduction.     

流态化还原铁精粉粘结过程试验研究

采用热态可视化流化床装置研究了铁精粉流态化还原过程,描述了流化床粘结失流过程的一些宏观表现和颗粒的微观变化.研究发现,失流后不同还原剂引起的料层膨胀程度明显不同,例如用H2作还原剂时料层膨胀40%左右,而用CO时膨胀会达到82%,而且颗粒问的粘结强度也与还原剂的种类有关.同时,适当降低还原温度可以延缓失流的发生也得到了...     

Thermodynamic Analysis of Formation of Fluoride from Gangue in Bayan Obo Iron Concentrate Containing Fluorite

In order to fill up the deficiency of the theoretical basis about fluoride formation during Bayan Obo iron concentrate roasting process,the thermodynamic conditions of the interactivity between the components of the gangue and calcium fluorite were studied by means of thermodynamic calculation,DTA-TG thermal analysis and XRD characterization.The results revealed that KF,NaF and SiF4(gaseous)could be formed during the roasting process,and the tendency of the generation of KF is greater than that of NaF or SiF4 in standard state.Besides,the results of roasting experiments showed that the products of KCaCO3 F and KCaF3 formed in the temperature range of 800-1 250℃and KF appears when the roasting temperature was higher than 1 250 ℃in K2O-CaF2 system.For the Na2O-CaF2 system,the product of NaF appears at temperature higher than 1 050 ℃.The formation reaction of gaseous SiF4 with solid phase CaO·SiO2in SiO2-CaF2 system took place only at temperature higher than 1 150℃.In the natural potash feldspar-CaF2-CaO system,the fluorination reaction products involved KF at temperature higher than 1 270℃,while in the natural aegirine-CaF2-CaO system,NaF formed at temperature higher than 980℃ during roasting process.     

Effect of Coating MgO on Sticking Behavior during Reduction of Iron Ore Concentrate Fines in Fluidized Bed

The effect of coating MgO with different methods on sticking behavior during the reduction of iron ore fines was investigated, at 1073 K with 70%CO–30%H₂ gas mixture in a visualization fluidized bed. It was found that coating MgO on particle surface could extend fluidization time from 12 min to more than 80 min, and improve the degree of metallization from 22% to more than 80%. The expansion level of bed after defluidization could also be obviously decreased. To achieve a similar effect, the initial coating content with solution method was less than that with powder method. The reason was that coating MgO could effectively insulate the contact of metallic iron on particle, which provided the reaction time for carbon deposition and the production of Fe₃C with low stickiness. Therefore, the decrease of metallic iron on particle surface led to the decrease of particle stickiness at high temperature.     

配加高镁铁精粉的烧结配料结构优化

为了在烧结生产中配加低价、低品位的高镁铁精粉替代南非进口粉,淮钢烧结厂运用了烧结生产配料理论测算和成本分析等手段并结合高镁铁精粉烧结工业试验进行了配料结构优化,达到了降本增效的目的。     

应用数理统计技术对烧结所用原料铁精粉批次品质的评价

天津众冶公司采用数理统计技术，对不同批次铁精粉的品质进行评价，确定质量稳定的铁精粉供应商，为满足烧结生产提供精料。     

In-situ measurement of mineral phase transition and kinetics in roasting process of Bayan Obo mixed rare earth concentrate by sodium carbonate

In this study, the Bayan Obo rare earth concentrates mixed with Na₂CO₃ were used for roasting research. The phase change process of each firing stage was analyzed. The kinetic mechanism model of the continuous heating process was calculated. This study aims to recover valuable elements and optimize the production process to provide a certain theoretical basis. Using X-ray diffraction (XRD), Fourier infrared spectroscopy, scanning electron microscopy with energy dispersive spectrometry, the reaction process and the existence of mineral phases were analyzed. The variable temperature XRD and thermogravimetric method were used to calculate the roasting kinetics. The phase transition results show that carbonate-like substances first decompose into fine mineral particles, and CaO, MgO, and SiO₂ react to form silicates, causing hardening. Further, REPO₄ and NaF can directly generate CeF₃ and CeF₄ at high temperatures, and a part of CeF₄ and NaF forms a solid solution substance Na₃CeF₇. Rare earth oxides calcined at a high temperature of 750 °C were separated to produce Ce_0.6Nd_0.4O_1.8, Ce₄O₇, and LaPrO_3+x. Then, BaSO₄, Na₂CO₃, and Fe₂O₃ react to form barium ferrite BaFe₁₂O₁₉; the kinetic calculation results show that during the continuous heating process, the apparent activation energy E reaches the minimum in the entire reaction stage in the temperature range of 440–524 °C, and the reaction order n reaches the maximum, which indicates that the decomposition product REFO significantly impacts the reaction system and reduces the activation energy. The mechanism function is F(α) = [?ln (1?α)]^1/3. The reaction order n reaches the minimum in the temperature range of 680–757 °C, and the apparent activation energy E is large. The difficulty of the reaction increases during the final stage. The reaction mechanism function is F(α) = [1?(1?α)^1/3]². Observing the entire reaction stage, the step of controlling the reaction rate changes from random nucleation to three-dimensional diffusion (spherical symmetry).