钛精矿碳、氢还原机理及含钛物料与熔铁界面现象的研究
文献类型：学位论文
| 作者 | 王玉明 |
| 学位类别 | 博士 |
| 答辩日期 | 2007-06-06 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 袁章福 |
| 关键词 | 钛精矿 碳热还原 氢还原 动力学 润湿性 |
| 其他题名 | studies on reduction mechanism of ilmenite concentrate by carbon and hydrogen and interfacial phenomenon of Ti-contained materials and molten iron |
| 学位专业 | 化学工艺 |
| 中文摘要 | 我国拥有丰富的钛铁矿资源，生产钛白和海绵钛的主要原料都是四氯化钛，因此，四氯化钛在钛工业中占据重要地位。由于生产四氯化钛的沸腾氯化法要求原料中二氧化钛含量大于85％，另外，因环保要求硫酸法钛白生产的原料也应有较高的二氧化钛品位。随着自然金红石的逐渐消耗和枯竭，利用储量丰富的钛铁矿作为原料制备富钛料代替自然金红石已成必然，从而对钛铁矿进行还原分离铁提高二氧化钛品位变得非常重要。 论文通过HSC计算化学软件对钛精矿碳热还原热力学进行了计算，从理论上解析了反应平衡时可能生成的各种组分及它们之间的关系。 利用热重分析方法对钛精矿碳热还原动力学进行了研究，结果发现：碳热还原中温度低于1100℃，反应属于化学反应控制，还原反应表观活化能为265 kJ/mol；在1100～1250℃之间，反应属于混合控制区，反应表观活化能为164 kJ/mol；当温度高于1250℃时，反应为扩散控制，控制反应速度的因素是反应物及产物的扩散速度，反应表观活化能为157 kJ/mol。通过XRD分析了不同温度下的还原产品。通过光学显微镜对样品表面形貌进行了观察，发现较高温度有利于更细小铁颗粒的生成。同时对锰、镁氧化物杂质对还原反应的影响进行了解析。对比钛精矿及铁精矿的碳热球团还原发现，由于钛精矿中钛酸铁多了一个复合物的离解反应，故钛精矿的碳热还原较铁精矿更难。 添加剂催化碳热还原反应的研究表明，随着添加剂离子半径的增加，碱金属氯化物的催化效果越明显，碱金属氯化物的催化效果顺序为CsCl > KCl > NaCl > LiCl。由添加剂催化碳热还原反应动力学分析知，产物层扩散阻力影响较大。氟化物能降低钛精矿碳热还原的扩散阻力，却明显增加了界面反应阻力，造成反应初期没有促进效果的现象。 对氢浓度、温度、预氧化等对钛精矿氢还原的影响进行了研究。氢还原动力学分析表明：在800～1000℃温度范围内30％氢还原和在900～1000℃温度范围内40％氢还原反应符合混合控制；纯氢还原中800℃和850℃符合扩散控制，在900～1000℃温度范围内为混合控制。在800～1000℃温度范围内30％氢还原界面化学反应及扩散的表观活化能分别为140 kJ/mol和149 kJ/mol；在900～1000℃温度范围内40％氢还原界面化学反应及扩散的表观活化能分别为99 kJ/mol和101 kJ/mol；在900～1000℃温度范围内纯氢还原界面化学反应及扩散的表观活化能分别为78 kJ/mol和94 kJ/mol。在900℃30％氢还原条件下，预氧化使氢还原钛精矿的还原程度大约提高了10％。钛精矿氢还原表观活化能与钛精矿碳热还原表观活化能相比，要远远低于其表观活化能，从而钛精矿的氢还原更为容易。 利用表面张力测定装置对熔铁与钛矿还原球团的润湿性及界面渗透现象进行观察，发现还原程度越高的球团与熔铁之间的润湿角越大分离功越小，预示高温有利于铁和钛氧化物的分离。对凝固后的试样分析表明，熔铁与不同碳还原球团基板有不同程度渗透，而与氢还原球团基板未发现明显渗透。 |
| 英文摘要 | There are abundant resources of the ilmenite ore in China. Titanium tetrachloride is important to titanium industry as the intermediate raw material for the production processes of titanium dioxide and titanium sponge. In present, the main production method of titanium tetrachloride in industry is bubble fluidized bed chlorination. The content of titania as raw material for chloride process must be higher than eighty five percent, and the content of titania as raw material for sulfate process should have a good rank due to the demand of environment protection. However, the resources of high-grade titanic mineral rutile are decreasing worldwide. Therefore, the utilization of low-grade minerals such as ilmenite has attracted more attention. Due to their high impurities content, especially iron oxides, the processes of refining low-grade ilmenites to Ti-riched materials become indispensable. The thermodynamics of carbothermic reduction of ilmenite concentrate was calculated by HSC that is a kind of chemistry computational software. The possible equilibrium components and their compositions relation were studied from the thermodynamical theory. The reduction reaction kinetics and mechanism of Bama ilmenite concentrate with graphite were investigated by using thermogravimetric analysis system. The results of kinetics showed that at temperatures below 1100℃ chemical reaction was the rate-controlling step, at 1100 to 1250℃ mixed controlling was rate-controlling step, above 1250℃ diffusion through the product layer controlled the reaction. The activation energies of the three steps were 265 kJ/mol, 164 kJ/mol and 157 kJ/mol respectively. The reduction products were determined under different temperatures by XRD analysis. Investigation of the micrographs by optical microscope showed the fine iron particle was in favor of being formed at high reduction temperature. The effects of manganese and magnesium oxides were elucidated. The reduction results of ilmenite concentrate with carbon was contrasted to that of iron concentrate with carbon and it was found the reduction of iron concentrate with carbon was easier than ilmenite concentrate owing to required energy for separation of FeTiO3 in ilmenite concentrate. The catalytic effects of alkali and alkaline earth and chloride additives were investigated and found the catalytic effect enhanced as the radius size of alkali ion increased. Under the same experimental conditions, the catalytic effects of different alkali additives could be ranked as follows in terms of their effectiveness: CsCl > KCl > NaCl > LiCl. The kinetics was also studied to find diffusion resistance of product layer had great effect on reductive reaction. When fluoride was added, resistance of diffusion increased and that of interface chemical reaction decreased. Therefore, the reaction rate couldn’t be enhanced during the beginning of the reaction. The effects of hydrogen concentration, temperature, preoxidization were studied. The reduction of the pellet with hydrogen proceeded topochemically. The results of kinetics showed that mixed controlling was the rate-controlling step in the ilmenite reduction with 30vol% H2 at the temperatures from 800 to 1000℃ and with 40vol% H2 at the temperatures from 900 to 1000℃. The diffusion and mixed controlling were the controlling steps with pure hydrogen at the temperatures from 800 to 850℃ and from 900 to 1000℃, respectively. The reduction of the ilmenite with 30vol% H2 at the temperatures from 800 to 1000℃, with 40vol% H2 at the temperatures from 900 to1000℃, with pure hydrogen at the temperatures from 900 to 1000℃, the activation energies of interface chemical reaction and diffusion were 140 kJ/mol and 149 kJ/mol, 99 kJ/mol and 101 kJ/mol, 78 kJ/mol and 94 kJ/mol, respectively. The reduction degree of ilmenite concentrate with 30vol％hydrogen at 900℃ increased ten percent approximately owing to its preoxidization. The activation energies of reduction reaction with carbon were more than that with hydrogen, so it was easier for hydrogen to reduce the ilmenite concentrate than carbon. Wetting and interfacial permeability of pig iron and reduction pellet substrate systems were observed by using of the testing device of surface tension. The results showed the higher reduction degree of the substrate was, the bigger contact angle between molten iron and substrate was, the less work of adhesion was, which suggested iron and titanium oxides had good separation at high temperature. Permeability of molten iron into pellet as substrate reduced by carbon could be observed to different extent. However visible permeability of molten iron and pellet reduced by hydrogen didn’t be observed. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 161 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1101]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 王玉明. 钛精矿碳、氢还原机理及含钛物料与熔铁界面现象的研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2007. |
入库方式： OAI收割
来源：过程工程研究所
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