高钙镁钛精矿制备高品质富钛料新工艺及理论研究

【作者】 黄孟阳；

【导师】 彭金辉；

【作者基本信息】 昆明理工大学 ， 有色冶金， 2008， 博士

【摘要】 针对攀枝花钛精矿的特点和处理工艺中存在的问题，结合微波加热在冶金中应用的优点，本论文提出了微波处理高钙镁钛精矿制备高品质富钛料的新工艺，并进行了微波加热还原钛精矿、还原产物选矿分离小试和扩大试验研究，同时研究了钛精矿常规加热还原动力学、微波场中钛精矿碳热还原动力学以及初级富钛料常规加热和微波加热浸出动力学。采用钛精矿还原产物的XRD和吸波特性测试相结合的方法揭示了钛精矿还原过程的反应机理；通过对比常规加热和微波加热初级富钛料浸出和浸出动力学，发现微波浸出时残留铁、钙和镁的浸出率获得极大的提高，突出了微波处理高钙镁钛精矿的优势。论文把微波谐振腔微扰法测吸波特性的方法应用到钛精矿微波加热还原工艺中，发现了物料的吸波特性突变粒度范围和比例，合适的粒度和比例可以提高微波的能量利用率和减少试验量。测试结果表明，钛精矿、焦炭、钛精矿氧化产物、添加剂和标准物质的吸波特性依次减弱；高钙镁钛精矿合适的粒度为180～150μm或者90～74μm，结合升温过程确定了粒度为90～74μm；钛精矿的吸波特性好于椰壳炭、无烟煤和焦炭，并且三者配入量分别为20％、14％和5％的混合物发生了吸波特性的突变；钛精矿氧化产物的吸波特性弱于椰壳炭、焦炭和石墨，并且三者配入量分别为30％、30％和10％的混合物吸波特性较好；根据氧化产物的吸波特性得到微波氧化条件为：氧化温度800℃，氧化时间20min和钛精矿粒度为180～125μm。论文提出了微波加热还原-选矿分离-微波浸出制备高品质富钛料新工艺，并进行了单批球团料60kg公斤级微波还原扩大试验研究。论文通过条件试验得到了最佳工艺条件并在小试的基础上进行了单批球团料60kg公斤级微波还原扩大试验研究，结果表明，各项指标与小试吻合，说明了小试工艺参数可靠性和产物指标的稳定性。对微波加热还原产物进行了选矿分离试验研究，得到了选矿分离的最佳工艺条件并以小试最佳工艺参数进行了公斤级选矿分离扩大试验研究，确定了选矿分离联合工艺流程并获得TiO₂品位为72．01％初级富钛料和两种副产品铁粉。以获得的初级富钛料为浸出原料，进行了浸出试验研究，得到了合适的工艺条件。全工艺流程研究结果表明，所获得的富钛料指标为：二氧化钛品位为92．73％，钙镁含量为0．207％，铁含量为0．8％，MnO含量为0．13％，铁粉副产品的TFe含量为94．35％；微波加热还原钛精矿和常规加热还原相比，还原时间缩短了50％以上；微波浸出和常规浸出相比，微波浸出时间缩短了94～96％，铁浸出率是常规的1．82倍，镁的浸出率是常规的57．8倍。论文推导出在本试验条件下常规浸出和微波浸出初级富钛料动力学方程分别为：φ=K₀·r^-1·[HCl]^0.4083·exp（-55423.6/RT）（常规浸出）φ=K₀·r^-1·[HCl]^0.5056·exp（-44381.8/RT）（微波浸出）动力学试验研究表明，常规加热条件下，残留铁的浸出率最大为52．4％，钙镁几乎没有被浸出；微波加热条件下，残留铁的浸出率最大为95．8％，镁的浸出率最大为89．12％，钙的浸出率最大为52．2％。可见，微波加热浸出时铁、钙和镁浸出率有显著提高，符合从浸出渣中获得高品质富钛料的技术路线，体现了微波加热浸出对钙镁去除率高的优势。论文推导出钛精矿还原度为：R=4（16y+56x）(ΔW_Σ-f_A-PW-ΔW_TiO2/7（16y+56x+112）×100％，发现氯化钠与硼酸钠对钛精矿还原存在协同催化的作用。以硅酸钠、氯化钠、硼酸钠和三者混合物为添加剂，进行了钛精矿碳热还原催化动力学研究。结果表明，四种添加剂还原反应过程均受铁晶粒成核和生长控制，发现氯化钠与硼酸钠对钛精矿的还原存在协同催化的作用，得到活化能为72．49kJ／mol，比单一的氯化钠或硼酸钠催化活化能分别降低39．54kJ／mol和28．25kJ／mol。表观活化能比两者都低，说明达到协同催化的效果。在1150℃，协同催化的还原度较硅酸钠催化提高47．03％。硅酸钠催化前期表观活化能为36．45kJ／mol，后期为135．14kJ／mol，随硅酸钠含量的增加，其还原度升高，在1150℃，还原度为22．74％。氯化钠催化的表观活化能为112．03kJ／mol，比硅酸钠催化钛精矿还原的后期活化能降低23．11kJ／mol。在1150℃，氯化钠催化的还原度比硅酸钠催化提高41．22％。硼酸钠催化的表观活化能为100．74kJ／mol，比硅酸钠催化钛精矿还原的后期活化能降低34．4kJ／mol。在1150℃，硼酸钠催化的还原度比硅酸钠催化提高32．21％。论文推导出微波场中钛精矿碳热还原铁晶粒生长动力学模型公式：lnkλ/cosθ（β_t²-β₀²）^1/2=-E／16．628T+C，该模型从晶粒粒径大小揭示铁晶粒成核和生长规律，并能获得激活能，对含铁矿石常规加热或微波加热铁晶粒生长具有适应性。研究表明，在铁晶粒生长过程中，铁晶粒粒径的lnd_t和1／T存在着线性关系，微波场中铁晶粒生长过程前期和后期的激活能分别31．04kJ／mol和69kJ／mol，与复合添加剂协同催化表观活化能比较接近。lnU和1／T也存在着线性关系，分别采用吸波特性参数的lnU和晶粒粒径大小的lnd_t描述铁晶粒生长具有相同的规律，即前期激活能小，后期变大。采用产物的吸波特性衰减电压等参数和产物的XRD分析表征了产物的吸波特性突变，发现组分含量的变化及新物相的生成是引起吸波特性突变原因。吸波特性和XRD分析表明，选矿分离产物吸波特性突变的原因是Fe、FeTi₂O₅和TiO₂等组分含量的变化所产生的。常规加热钛精矿还原反应开始有铁生成的温度为900℃，微波加热钛精矿还原反应开始有铁生成的温度为850℃。吸波特性的突变温度点具有相似规律，突变的原因是Fe的生成、FeTi₂O₅和TiO₂的含量变化引起吸波特性叠加所产生的。为吸波特性和XRD相结合的分析方法检测物质的生成和含量的变化提供借鉴作用。总之，本论文提出了一种微波处理高钙镁钛精矿制备富钛料的新工艺。新工艺拓宽了现有的攀枝花高钙镁钛精矿制备高品质富钛料工艺路线，对提高攀枝花钛精矿利用率具有较大的现实意义。论文采用的吸波特性和XRD测试相结合的方法，为微波在冶金中应用特别是钛冶金提取的应用提供理论依据。更多还原

【Abstract】 In this thesis, a novel technology of preparing titanium-rich materials from ilmenite concentrate with high CaO and MgO content was put forward in order to deal with the characteristics of Panzhihua ilmenite concentrate, and serial problems in the ilmenite concentrate treatment processing, combined with the advantages of microwave heating in metallurgical application. At the same time, ilmenite concentrate reduction by microwave heating, small-scale and pilot-scale experimental studies of ore milling separation of reduction product, the reduction kinetics of ilmenite concentrate by conventional heating、kinetics of iron grain nucleation and growth in microwave field and leaching kinetics of primary titanium-rich materials by conventional and microwave heating were investigated. The reaction mechanism of ilmenite concentrate reduction was evaluated by using the measurement of microwave absorbing characteristics and XRD characterization of reduction product of ilmenite concentrate. Through the comparsions of the leaching and leaching kinetics of titanium-rich material by conventional and microwave heating, it was found that the leaching ratios of residual iron, CaO and MgO were enhanced greatly using microwave leaching, indicating the the advantages of dealing with ilmenite concentrate with high CaO and MgO content by microwave heating.The method of mearsuring microwave-absorbing characteristics using the technique of microwave cavity perturbation was used in the process of reduction of ilmenite concentrate by microwave heating, and obtained the particle size range and percent of materials microwave-absorbing characteristics mutation, and proper particle size and porcent could enhance the utilization ratio of microwave energy.It was found that the microwave-absorbing characteristics of ilmenite concentrate, carbon, oxdized ilmenite additive and standard material decrease in turn. The appropriate particle size for ilmenite concentrate with high CaO and MgO content was 180-150μm or 90-74μm. Taking into considerization of temperature rising process, the particle size was chosen to be 90-74μm. The microwave-absorbing characteristics of ilmenite concentrate was better than those of coconut carbon,coke and anthracite. And furthmore it was found that there was a mutation of microwave-absorbing characteristics for the ilmenite concentrate when the content of coconut carbon, anthracite and coke were 20%,14% and 5%, respectively. The microwave-absorbing characteristics of oxdized ilmenite concentrate was worse than those of coconut carbon, coke and anthracite. And furthmore it was found that the microwave-absorbing characteristics for the ilmenite concentrate was better when the mass content of coconut carbon, anthracite and coke were 30%, 30% and 10%, respectively. According to the microwave absorbing characteristics of oxidized product, the oxidation conditions by microwave heating were obtained as follow: the oxidization time was 20 min, oxidation temperature was 800℃and the particle size was 180-125μmA process of the titanium-rich material production by using microwave heating reduction, ore milling separation and microwave leaching was put forward on the basis of researches of microwave absorbing characteristics. The optimal conditions for ilmenite concentrate reduction by microwave heating were obtained through small scale reduction experiments by microwave heating. The expanding experiment of 60 kg was investigated on the basis of small scale experiments. Experimental results showed that the parameters obtained were in consistent with those of small scale experiments, indicating that the reliability and stability of small scale experiments. The optimal conditions for ore milling separation were obtained through the ore milling separation experiments of reductive product by microwave heating. The kilogram-scale expanding experiment for ore milling separation was carried out using process parameters obtained through small scale experiments, the union process of ore milling separation was determined and obtained primary titanium-rich materials with 72.01% TiO₂ and two kinds of iron by-products. The leaching experiment was carried out using primary titanium-rich materials obtained as leaching materials and got the optimal process conditions. The research results showed that the index of titanium -rich material is as follow: titanium dioxide 92.73%; the contents of CaO and MgO 0.207%; the content of iron 0.8%; the content of MnO 0.13%. The time needed for ilmenite concentrate reduction by microwave heating was shorten 50% compared with that of conventional heating. The leaching time by microwave heating was shorten 94～96% compared to that of leaching by conventional heating. The leaching ratios of Fe and Mg by microwave heating were 1.82 and 57.8 times than those by conventional heating.The kinetics equations of primary titanium-rich materials by conventional and microwave leaching under the present experimental conditions were deduced.φ=K₀·r^-1·[HCl]^0.4083·exp（-55423.6/RT）（conventional leaching）φ=K₀·r^-1·[HCl]^0.5056·exp（-44381.8/RT）（microwave leaching）Kinetic experiments showed that the maximum leaching ratio of residual iron by conventional heatingg was 52.4%, while Ca and Mg could not be leached out. The maximum leaching ratios of residual iron, Mg and Ca by microwave heating were 95.8%, 89.12% and 52.2%, respectively. It was apparent that the leaching ratios of Fe, Ca and Mg were enhanced greatly, which meets the technological procedure of obtaining high quality titanium-rich materials from leaching slag, indicating the advantages of removing Ca and Mg by microwave heating.The reduction degree expression equation was deduced asR=4（16y+56x）(ΔW_Σ-f_A-PW-ΔW_TiO2/7（16y+56x+112）×100% on the basis of reduction degreedefinition and weight loss determination. The study on carbothermal reduction catalytic kinetics of ilmenite concentrate was carried out using sodium silicate, sodium chloride, sodium boratio and their mixture as additives. The results showed that four additives reductive reaction processes were all controlled by iron grain nucleation and growth. It was found that sodium chloride and sodium boratio had concerted catalysis effect on the reduction of ilmenite concentrate.The activation energy obtained was 72.49 kJ/mol, and was 39.54 and 28.25 kJ/mol lower respectively than those of single catalysis reduction using sodium chloride and sodium boratio, respectively, showing the concerted catalysis effect of sodium chloride and sodium boratio. The reduction degree by concerted catalysis was enhanced 47.03% than that of using sodium silicate at the temperature of 1150℃. The early and late apparent activation energy catalyzed by sodium silicate were 36.45 andl35.14 kJ/mol, respectively. With the content of sodium silicate increased, the reduction degree increased. The reduction degree was 22.74% at 1150℃. The apparent activation energy catalyzed by sodium chloride was 112.03 kJ/mol, and was 23.11 kJ/mol lower than that of late apparent activation energy catalyzed by sodium silicate. The reduction degree catalyzed by sodium chloride was enhanced 41.22% compared with that of using sodium silicate at temperature of 1150℃. The apparent activation energy catalyzed by sodium boratio was 100.74 kJ/mol, and was 34.4 kJ/mol lower than that of late apparent activation energy catalyzed by sodium silicate. The reduction degree catalyzed by sodium boratio was enhanced 32.21% compared with that of using sodium silicate at the temperature of 1150℃.According to the kinetics model of titanium dioxide grain nucleation and growth in solution, the iron grain growth kinetics model of ilmenite concentrate by carbothermal reduction in microwave field was deduced. Itwas lnkλ/cosθ（β_t²-β₀²）^1/2=-E/16.628T+C. This model revealed the rules of irongrain nucleation and growth from the particle size, and got the activation energy of iron grain nucleation and growth at different period. Besides, this model possessed adaptability to the iron grain nucleation and growth of iron ore by conventional heating and microwave heating. The kinetics of iron grain nucleation and growth in the ilmenite concentrate reduction process in microwave filed showed that there was linearity between lnd_t and 1/T in the process of iron growth. The early and late activation energy of in period iron growth was 31.04 kJ/mol and 69 kJ/mol, respectively and were close to the apparent activation energy of synergistic catalysis. There was linearity between lnU and 1/T. The rules of iron growth described by microwave-absorbing characteristics parameter lnU was the same to that described by lnd_t; and the early activation energy was small, then enlargedin the late period.Mutation of microwave-absorbing characteristics of reduction products and ore milling separation products by conventional heating and microwave heating was characterized by using microwave-absorbing characteristics attenuation voltage parameters and the products was also characterized by XRD. It was found that the reason of causing microwave-absorbing characteristics mutation was the changes of the contents of components and new phase formations. The results showed that the reasons for microwave-absorbing characteristics mutation of ore milling seoaration products were the content changes of Fe、FeTi₂O₅ and TiO₂.The temperature of Fe phase formation in ilmenite concentrate reduction reaction by conventional heating was 900℃, while the temperature of Fe phase formation in ilmenite concentrate reduction reaction by microwave heating was 850℃. There was similarity between microwave-absorbing characteristics mutation temperature by conventional heating and microwave heating. The resaons for mutation were the formation of Fe and overlapping of microwave-absorbing characteristics caused by changing of the contents of FeTi₂O₅ and TiO₂., which provided a guidance for measurement of the formations of new matters and changing of contents with the analysis method of combination of microwave-absorbing characteristics and XRD.Generally,a novel process of making titanium-rich material from ilmenite concentrate with high CaO and MgO content by microwave heating was put forward in this thesis. The quality of titanium-rich material-titanium dioxide and the contents of other imurities produced by new process met the requirements for materials used in the production of TiO₂ by chlorinated boiling process. The new process broadened the present process route for producing high quality titanium-rich material from ilmenite concentrate with high CaO and MgO contents in Panzhihua, Sichuan province, having great significance for ehancing the utilization ratio of ilmenite concentratein Panzhihua. The methods of mearsurement of microwave-absorbing characteristics and XRD characterization used in thesis provided the application of microwave in metallurgical industry, especially in titanium metallurgy with theorical basis.更多还原