Entrained-flow chlorination of ilmenite to produce titanium tetrachloride and metallic iron

The reaction of FeCl₂ vapor with TiO₂ in ilmenite to yield TiCl₄ and metallic iron was studied at 1523 to 1723 K in an entrained-flow reactor. Ilmenite/carbon mixtures containing carbons with internal surface areas from 1 to 600 m²/g were milled to various average particle diameters ranging from 6 to 65 μm. Up to 44 pct of the stoichiometric FeCl₂ reacted at the highest retention time of 34 seconds when a sixfold excess of FeCl₂ vapor was used. Maximum ex-perimental reaction yields were only about two thirds of the theoretical yield calculated for equilibrium conditions. For large particles, a negative effect of temperature on reaction rate indicated that the reaction rate was controlled by ash layer diffusion resistance. For small par-ticles, under the higher turbulence conditions, the early stages of reaction appear to be influ-enced by film mass transfer.     

固态还原钛铁矿生产钛渣新技术

钛铁矿的还原热力学表明,钛铁矿的还原难度大于普通铁矿。动力学研究表明,通过粉体细化,可以加速钛铁矿的还原速度;通过晶粒长大技术将还原后的细微铁晶粒长大到一定粒度,通过简单磁选,即可得到铁产品和钛渣。开发的钛铁矿固态还原与晶粒长大新工艺具有反应温度低、无需高温熔分等特点,从而实现高效率、低能耗及低成本生产钛渣和铁产品。     

Study of a titaniferous magnetite chlorination at high temperature

The chlorination of a titaniferous magnetite with low content in Ti and Fe has been studied between 1273 and 2273 K. Most of the hercynite and ilmenite initially present are decomposed during the gas-solid phase reaction between 1273 and 1823 K. Considerable ilmenite decomposition and FeCl₃evolution already occur at 1273 K, leaving a residue consisting of TiO₂, Fe₂O₃-TiO₂ (pseudobrookite), and about 50 pct of each of the Cr and Mg initially present. X-ray diffractograms shown the formation of Al₂TiO₅ which contributes to the stabilization of TiO₂ up to 1773 K, above which temperature significant decomposition of Al₂TiO₅ is observed. At the melting point of the titaniferous magnetite sample (around 1823 K), the presence of both solid and liquid phases result in a considerable decrease in the chlorination rate. In this respect, heating the sample under helium up to the melting point, so that liquid and solid phases are obtained at equilibrium, yields two structures replacing the magnetite present just prior to melting. One of these structures is of the spinel Fe₂TiO₄ type, while the other is a combination of the spinel types MgAl₂O₄, FeAl₂O₄, and MgCr₂O₄. When the sample is chlorinated, a high proportion of the initial Cr (90 pct) and Ti (80 pct) are found in the chlorination residue at the early stages of fusion, together with 13 pct of the initial Fe. Chlorination of the liquid phase between 1823 and 2273 K shows a steady decrease of Ti and Cr in the chlorination residue, associated with an increase of Fe content.     

石油焦中硫含量对熔盐氯化过程的影响

利用HSC软件计算了硫在熔盐氯化过程中发生化学反应的标准吉布斯自由能,研究了石油焦中硫含量对粉磨性质、熔盐氯化过程控制、粗四氯化钛质量和精制除杂的影响。结果表明,硫在熔盐氯化体系中的主要反应产物是SO_2、COS、SO_2Cl_2和SOCl_2;硫含量不会影响熔盐氯化过程连续稳定运行,但会导致熔盐、收尘渣、尾气和粗四氯化钛中硫含量增大;硫在精制过程中难以除去,应选择硫含量低于0.45%的石油焦。     

四氯化钛除钒尾渣钠化焙烧动力学研究

基于非等温热重分析研究Na2CO3添加量和升温速率对含钒尾渣氧化的影响规律,采用Kissinger-Akahira-Sunose(KAS)法计算了含钒尾渣氧化过程活化能和指前因子,并通过Coats-Redfem法推断机理函数并建立不同阶段所适用的动力学方程.结果表明:含钒尾渣完全氧化的温度为700℃,随Na2CO3添加...     

Kinetics of chlorination of niobium pentoxide by carbon tetrachloride

Kinetics of the chlorination of Nb₂O₅ powder by CCl₄ vapor in mixture with N₂ in a static bed in the temperature range of 698 to 853 K were carried out at different partial pressures of CCl₄ (p _{CCl 4}), varying from 0.10 to 0.75 atm. The fraction of Nb₂O₅ chlorinated R at p _{CCl 4} of 0.6 atm in the temperature range of 698 to 773 K was found to be proportional to time t, and the activation energy E is calculated to be 112 kJ/mole. Results on the effect of p _{CCl 4} (0.4, 0.6, and 0.75 atm) at 723 K suggest that the rate v (R/min) is proportional to p _{CCl 4} ^1.5. However, at p _{CCl 4} of 0.2 atm, R is not linear with t, rather, R ^1/2 is linear with t. Based on these results, two mechanisms, one at low p _{CCl 4} (0.2 atm) and another at higher p _{CCl 4} values, in the temperature range of 698 to 773 K have been suggested. Similar studies in the higher temperature range (793 to 853 K), where p _{CCl 4} used to decompose to elemental chlorine and carbon, were also carried out. At all temperatures and p _{CCl 4} values, R is found to be directly proportional to t. At two higher p _{CCl 4} (0.4 and 0.6 atm), v is proportional to p _{CCl 4} ^1.5, whereas at two lower p _{CCl 4} (0.1 and 0.2 atm) it is proportional to p _{CCl 4} ^1.5. The E values obtained in the temperature range of 793 to 853 K at p _{CCl 4} of 0.6 and 0.2 atm are found to be 57 and 115 kJ/mole, respectively. In this higher temperature range, two different reaction mechanisms have been proposed.     

高温液态矿渣在微晶玻璃生产中的应用研究

分析了微晶玻璃的性能特点和生产工艺，探讨了液态矿渣在微晶玻璃生产中应用的可行性，证实了液态矿渣用于微晶玻璃生产不但可以利用矿渣的显热，而且具有良好的经济效益和很高的社会价值．     

含钛高炉渣渣钛分离研究

对某钢厂高钛型高炉渣进行了渣钛分离研究,确定了以NaOH作为分离剂制取偏钛酸晶体粉末的工艺路线,实现了合钛高炉渣资源的有效利用.含钛高炉渣中的钛、硅、铝氧化物在高温下与NaOH发生发应,生成相应的含氧酸钠盐,经过水浸和酸洗即可得到偏钛酸结晶.实验表明,温度对分离效果的影响显著,当渣与分离剂之比为50∶33、焙烧温度达1 350℃时,效果最佳,生成的偏钛酸量最大.     

一种改性钛渣钛组分的分离方法

研究了碱浸出过程中的影响因素,考察了浸出温度,NaOH溶液的浓度,以及物料粒度和液固比等因素对于浸出效果和回收率的影响.得到了碱浸阶段适宜的工艺条件为:溶液中NaOH的质量分数为15％、浸出温度100℃、浸出时间6h、液固比20 mL/g、钛渣粒度小于38 μm,搅拌速度500 r/min.采用三段浸出的方法获得了品位...     

微波场下的钒渣氯化动力学

研究了微波加热条件下（500～800 ℃）,AlCl₃氯化钒渣中有价金属Fe、Mn、V和Cr变温动力学。通过X射线衍射和扫描电镜能谱表征了氯化产物随时间的物相演变和形貌变化,考察了AlCl₃/钒渣的质量比和熔盐配比对氯化提取率的影响。结果表明,AlCl₃/钒渣的质量比为1.5、(NaCl-KCl)/AlCl₃熔盐质量比为1.66∶1时Fe、Mn、V和Cr的提取率最佳,分别为91.66%、92.96%、82.67%、75.82%和63.14%,微波加热30 min,5种元素的提取率达到或者超过常规加热方式6 h的氯化提取效果。通过热力学和动力学分析,橄榄石相优先于尖晶石相发生氯化反应。而且V和Cr的氯化反应速度小于Fe和Mn。Fe和Mn氯化过程为扩散控制,其非等温扩散活化能为17.02和17.10 kJ·mol?1, V和Cr在氯化过程中的限制性环节为界面化学反应,其表观活化能分别为40.00和50.92 kJ·mol?1;微波与熔盐耦合强化氯化反应的机理可以描述为扩散作用增强和局部化学反应增强。      

Kinetics of chlorination and microstructural changes of xenotime by carbon tetrachloride

Among the rare earth minerals, fluorides, phosphates, and oxides have received attention from the rare earth industry. Traditional methods of decomposition of these minerals, usually alkaline or acid processes, involve several operations. Another possibility to obtain lanthanide chlorides or oxychlorides is reacting the mineral with chlorinating agents, such as gaseous chlorine, hydrogen chloride, thionyl chloride, and carbon tetrachloride, reducing the operation costs and making the process less complicated. In this context, we investigated the decomposition of xenotime using carbon tetrachloride at temperatures from 873 to 1173 K and kinetic and mechanistic studies have been performed. Powder X-ray diffraction, scanning electronic microscopy, energy dispersive X-ray spectrometry, ultra-violet/visible spectroscopy, and thermal analysis techniques were used in this study. The results showed that the reaction follows the shrinking-unreacted-core model with formation of a product layer (lanthanide oxychloride), confirmed by powder X-ray diffraction. Moreover, microstructural changes of xenotime grains during the chlorination reaction were verified.     

Studies on the kinetics of carbon tetrachloride chlorination of tantalum pentoxide

Studies on the kinetics of chlorination of tantalum pentoxide powder by carbon tetrachloride vapor in dilution with nitrogen have been carried out by weight-loss measurements in two temperature ranges, i.e., 698 to 773 K and 793 to 853 K. The effect of time, temperature, and partial pressure of CCl₄ on the kinetics of chlorination of the powder Ta₂O₅, (−105+74 μm) has been investigated. In both the temperature ranges, the chlorination results have been found to fit the following relationship during the “initial periods:”

Kinetics of low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor

Low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor in dilution with nitrogen has been carried out. The effect of time, particle size, partial pressure of CCl₄ vapor (0.1 to 0.6 atm), and temperature (553 to 788 K) on the extent of chlorination of V₂O₅ has been investigated. The extent of chlorination of the oxide is found to increase with a decrease in its particle size. In all cases, the reaction followed a topochemical reaction model, obeying the following relationship:

Demanganisation of high manganese pig iron to produce high manganese slag

Abstract

Pig iron with a high manganese content makes further processing to steel using converter technology difficult and unprofitable. In the present study, external demanganisation of high manganese pig iron before the oxygen converter process has been investigated. Pilot plant experimental heats were designed and carried out to optimise the demanganisation process, to produce hot metal adequate for the conventional LD converter, and high manganese slag suitable for the production of silicomanganese. Various high manganese pig irons with different [Si]/[Mn] contents were treated by injection of various oxidisers at varying temperatures, slag basicities and injection rates. The optimum conditions for the demanganisation process have been attained by injection of an oxygen gas–manganese ore mixture at the injection rate of 6.8 L min^-1kg^-1 into molten high manganese pig iron with a [Si]/[Mn] ratio of 0.3 at an initial temperature of 1350°C and slag basicity of 0.3–0.4.     

用含钛熔分渣制备二氧化钛

钒钛磁铁精矿经高炉冶炼后,其中的TiO2几乎全部进入炉渣.为了有效利用钛资源,以含TiO249.36%(质量分数)的熔分渣为原料,经加碱焙烧、酸浸和水解后,制备海绵钛生产用原料一富钛料,研究焙烧温度对TiO2浸出率的影响,以及水解酸度对钛的水解率的影响.结果表明,焙烧温度对熔分渣中TiO2的浸出率影响很大:在低于1 000℃温度下加碱焙烧后钛的浸出率不高,而在1 300℃加碱焙烧后钛的浸出率高达92.2%;通过控制最终的水解酸度,钛的水解率可达91.5%,水解后产物为白色或浅黄色,颗粒较细,粒度为0.2～0.5 μm,TiO2品位达98.50%,可作为生产海绵钛的原料.     

流渣反应器内含钛高炉渣的流动特性

针对含钛炉渣在流渣反应器中的氧化工艺,采用模型实验方法研究熔渣在反应器内的流动特性与溶质扩散现象.考虑气液两相流动时,由于界面张力和浮力作用,黏性力的影响相对降低,故采用水来代替实际的高温液态高炉渣,通过底部吹入N2,模拟实际反应器内的流动情况.设计并排与错排两种喷吹方式,分别进行了物理水模型实验及数值模拟实验研究.物理水模型实验分别采用高速摄像法观测流场和刺激响应法测传质过程;数值模拟实验分析了不同位置的速度矢量分布和湍动能分布.结果表明错排喷吹方式的反应器内的流动特性好于并排方式.     

Studies on kinetics of low-temperature chlorination of ZrO2 by gaseous carbon tetrachloride

Studies on the kinetics of chlorination of ZrO₂. powder by carbon tetrachloride vapor in mixture with nitrogen in a low-temperature range of 650 to 825 K at different periods and partial pressures of carbon tetrachloride were carried out. The chlorination results at 650 and 675 K seem to follow a diffusion-controlled reaction model of Jander’s type: [1−(1−R)^1/3]² =k ₁t whereR is the fraction of ZrO₂ chlorinated in timet andk ₁ is the rate constant. The approximate activation energy of the process was calculated fromk ₁ values at the previously mentioned two temperatures and found to be 278 kJ/mole. For the chlorination in the temperature range of 700 to 750 K, the topochemical reaction model 1−(1−R) ^1/3 =k ₂t was followed. The rate constant,k ₂, was found to be proportional to the partial pressure of carbon tetrachloride. The activation energy of this reaction was calculated to be 154 kJ/mole. In the temperature range of 775 to 825 K, the rate of chlorination was found to be directly proportional to the time of chlorination following Langmuir’s Adsorption Isotherm. Because of the very high rate of chlorination and thermodynamic possibility of decomposition of CCl₄ above 773 K, the rate-controlling step has been suggested to be the decomposition of the adsorbed complex formed by ZrO₂ with carbon and chlorine atoms, obtained from the decomposition of CCl₄ vapor. The activation energy of the process was 54 kJ/mole. In view of nearly complete chlorination of ZrO₂ by CCl₄ in a very short period of about 15 minutes, at a temperature around 800 K and lesser possibility of formation of toxic product gases, the process is recommended for commercial application.     

含钛高炉渣熔化性研究

以高炉渣为主要原料,配入Ca(OH)_2、SiO_2、Al_2O_3和TiO_2化学试剂调整炉渣的组成,应用炉渣熔化特性测试仪半球点法,研究了含Al_2O_3 14.6%～17.6%、TiO_2 5%～7%高炉渣的熔化特性。结果表明:随着碱度的升高,炉渣的熔化性温度明显升高;TiO_2含量增加,炉渣的熔化性温度相应降低;适当提高渣中MgO的含量,可避免因Al_2O_3含量升高而引起的熔化性温度上升;炉渣的熔化性温度为1320～1420℃,熔化性良好。