攀枝花钛精矿真空碳热还原热力学模拟研究

在不同温度、体系压力和配碳量条件下,采用Fact Sage软件研究攀枝花钛精矿的真空碳热还原过程。结果表明:当温度为1 550℃,配碳量为12%时,随着压力的降低,挥发进入气相的各成分的总质量增加且渣相中的杂质含量降低,有利于提高还原反应进行的程度,获得高品质钛渣产物;当压力为100 Pa,温度为1 550℃时,随着配碳量的增加,有利于提高反应的还原效果;当压力为100 Pa,配碳量不变的条件下,温度高于1 300℃时,气相中开始出现Mg、Si O、Mn蒸气。当温度升高到1 700℃时,气相和渣相中各成分的含量趋于一个定值,渣中主要氧化物为Ti O2和Ti2O3,此时钛渣品位高达88%。     

铌精矿微波碳热还原反应动力学

针对白云鄂博铌精矿利用工艺的成本高、过程复杂、能耗大的特点,引入微波场,考察温度对铌精矿还原的影响,并对其进行形貌及动力学分析。结果表明,微波场中铌精矿碳热还原反应机理属于三维扩散,动力学方程为y=1-(2/3)α-(1-α)2/3,表观活化能Ea=131.654 kJ/mol,微波加热相对于常规加热具有加快反应速率、降低反应活化能的效果。     

钛精矿碳热还原制备碳氮化钛的研究

以钛精矿和石墨为原料,在氮气气氛下通过碳热还原法制备出碳氮化钛(Ti CN)粉体。结合XRD、SEM、化学成分分析和TG-DSG综合热分析研究了配碳量及反应温度对钛精矿碳热还原进程的影响。研究结果表明,配碳量的增加影响逐级还原反应温度以及反应总失重,当配碳量达到23%时碳氮化钛产物中出现游离碳。钛精矿碳热还原过程中铁氧化物优先还原,钛氧化物经逐级还原形成Ti CN,还原顺序为Ti O2→Ti4O7→Ti3O5→Ti N→Ti(C,N,O)→Ti CN。得到的碳氮化钛粉体呈微米级不规则形状。     

微波场中铌精矿碳热还原反应行为研究

目前铌资源的研究大多处于常规加热阶段,因为能耗高、冷中心等问题无法广泛推广。微波加热技术是一种新型加热技术,可以有效避免冷中心等问题。借助微波马弗炉将铌精矿碳热还原反应与微波加热相结合,探究还原温度、配碳比及保温时间对铌精矿金属化率的影响,以及金属颗粒的成长行为。研究结果表明,微波加热在碳热还原反应中优于常规加热,在微波加热下,还原温度为1100℃、保温30 min、配碳比为1时,金属化率达到94.84%;1000℃时NbC开始生成,1100℃时铌钛产物主要为(Ti,Nb)C,1300℃时,钛的产物主要以TiC形式存在。     

钒钛磁铁精矿低温综合利用新工艺

为了实现钒钛磁铁精矿的低温综合利用,采取碳热钠化工艺降低还原和熔分温度,考察了铁、钒、钛的富集回收情况。结果表明,钠化剂显著改善了钒钛磁铁精矿的还原及熔分效果,当钠化比为1.2时,1 100℃还原60 min即可达到90%以上的金属化率,1 250℃以上的温度下熔分后,铁的收得率达到96%,钒在铁水中的富集率为75%。熔分渣在无酸环境下经湿法处理后TiO_2含量达到77%,经还原熔分去除铁后品位可进一步提升。     

Vacuum Carbothermic Reduction of Panzhihua Ilmenite Concentrate: A Thermodynamic Study

Electric arc furnace is mainly used in the production of high titania slag; however, since impurities cannot be eliminated, this causes difficulty in the production of titania pigment with chlorination process. Consequently, removing impurities is the crucial way to deal with low-grade ilmenite, especially for the Panzhihua ilmenite concentrate in China. This article studied the theoretical calculation of vacuum carbothermic reduction of Panzhihua ilmenite concentrate. Thus, when the temperature was higher than 1600°C and the carbon amount was greater than 12%, all of the Fe almost entered into the gas phase. When the temperature was higher than 1300°C and the carbon amount was greater than 14%, magnesium also entered the gas phase. When the temperature was higher than 1100°C, most of the element manganese was volatilized in the gas phase. The TiO₂ grade increased with the increase in carbon amount (14%). When the temperature was higher than 1600°C and the carbon amount was less than 14%, the TiO₂ grade in the slag phase could reach the maximum value, which can be used for the chlorination process to prepare titanium dioxide.     

Effects of Temperature on Vacuum Carbothermic Reduction of Panzhihua Ilmenite Concentrate

Metallurgist - The vacuum carbothermic reduction of ilmenite concentrate was analyzed using SEM, EDS, and XRD, in combination with analysis of the Fe metallization rate. Results show that...     

Carbothermal Reduction of Quartz with Carbon from Natural Gas

Carbothermal reaction between quartz and two different carbons originating from natural gas were investigated in this paper. One of two carbons is the commercial carbon black produced from natural gas in a medium thermal production process. The other carbon is obtained from natural gas cracking at 1273 K (1000 °C) deposited directly on the quartz pellet. At the 1923 K (1650 °C) and CO atmosphere, the impact of carbon content, pellet structure, gas transfer, and heating rate are investigated in a thermo-gravimetric furnace. The reaction process can be divided into two steps: an initial SiC-producing step followed by a SiO-producing step. Higher carbon content and increased gas transfer improves the reaction rate of SiC-producing step, while the thicker carbon coating in carbon-deposited pellet hinders reaction rate. Better gas transfer of sample holder improves reaction rate but causes more SiO loss. Heating rate has almost no influence on reaction. Mass balance analysis shows that mole ratios between SiO₂, free carbon, and SiC in the SiC-producing step and SiO-producing step in CO and Ar fit the reaction SiO₂(s) + 3 C(s) = SiC(s) + 2 CO(g). SiC-particle and SiC-coating formation process in mixed pellet and carbon-deposited pellet are proposed. SiC whiskers formed in the voids of these two types of pellets.     

Enhancement Reduction of Panzhihua Ilmenite Concentrate with Coke and Conglomeration of Metal with Ferrosilicon

The particle size and metallization ratio of iron in reduced ilmenite have an important function in separating the metal from TiO₂‐rich slag in the electric arc furnace process. In this study, an ilmenite concentrate supplied by Panzhihua Iron and Steel (Group) Co. was reduced at 1380°C in an electric resistance furnace. The effects of Fe–Si addition and reduction time on the particle size and metallization ratio of iron in the reduced sample were analyzed. The metallization ratio of iron significantly increased with increasing Fe–Si amount and reduction time, and reached ≈90% after 40 min. However, the metallization ratio of iron was about 85% without Fe–Si addition. Meanwhile, the iron particle size increased with increasing Fe–Si amount; the growth was obvious with the addition of 1% Fe–Si. Moreover, the growth rate of the iron particle size also increased with increasing reduction time. The TG‐DTG curves indicated that the mass loss with Fe–Si addition was less than that without Fe–Si addition, and the temperature at which the maximum rate of mass loss rate was achieved was lower than that without Fe–Si addition.     

Gas Ionization During Carbothermal Reduction in Microwave Field and Its Effect

The reduction kinetic condition of the direct solid-phase reduction of metal oxide powder containing coal by microwave heating is better than that by the conventional heating process. The research shows that the gas ionization during carbothermal reduction accelerates the carbon gasification reaction and interface chemical reaction, and it also improves the kinetic conditions of carbothermal reduction. Thus, the formation mechanism and process of gas ionization as well as its effect during the carbothermal reduction of metal oxides containing coal by microwave heating are studied.     

Effect of Gas Atmosphere on Carbothermal Reduction and Nitridation of Titanium Dioxide

This article examined the reduction/nitridation of rutile in the He-N₂, Ar-N₂, and He (Ar)-H₂-N₂ gas mixtures, as well as pure nitrogen, in the temperature-programmed and isothermal experiments in a fixed-bed reactor. The extents of reduction and nitridation were determined from the off gas composition and LECO analysis. The off-gas composition was monitored using the infrared sensor (CO, CO₂, and CH₄) and dew point analyzer (H₂O). The phase composition of the reduced samples was analyzed using X-ray diffraction (XRD). The temperature and gas composition had a strong effect on the rutile reduction. The reduction was the fastest in the H₂-N₂ gas mixture, followed by a reduction in nitrogen; the rate of reduction/nitridation in the He-N₂ gas mixture was marginally higher than in the Ar-N₂ gas. The rate of titania reduction/nitridation in the He (Ar)-H₂-N₂ gas increased with the replacement of He (Ar) with hydrogen. The article also discusses the mechanisms of reduction/nitridation in different gas atmospheres.     

空气气氛下钒钛铁精矿碳热还原制备Fe-Ti(C,N)复合粉末

以钒钛铁精矿和煤粉为原料,在空气气氛下通过碳热还原法制备Fe-Ti(C,N)复合粉末。通过还原产物X射线衍射分析,对空气气氛下还原温度和配碳量对钒钛铁精矿碳热还原的反应过程以及物相演变进行了研究。结果表明,随着温度的升高,反应过程中的物相演变过程为:Fe_3O_4→Fe,Fe TiO_3→Fe Ti_2O_5→Ti_4O_7→Ti_2O_3→Ti(C,N),配碳量是使反应体系处于气相平衡的关键因素。在配碳量25%时,体系内CO、CO_2和N2的分压不能达到平衡或维持反应平衡的时间很短,钒钛铁精矿不能被还原或只能部分被还原为Ti(C,N)。在还原温度1 500℃,还原时间30 min,配碳量30%的条件下,还原产物中Ti C_(1-x)N_x的颗粒尺寸约为3μm,Ti C_(1-x)N_x的C/N值为0.491 5,x=0.67。     

全攀枝花钛精矿冶炼钛渣的生产实践

对25.5MVA半密闭圆形钛渣电炉使用全攀枝花钛精矿冶炼生产的情况进行分析,提出使用全攀枝花钛精矿冶炼酸溶性钛渣的方案。     

提升钛精矿品级的研究

利用氧化热处理和酸浸工艺提升钛精矿的质量等级,研究了氧化处理对钛精矿球磨前后晶体结构的影响及酸浸工艺提高钛精矿品级的效果。结果表明,经750~800℃氧化退火,钛精矿中物相转变较充分,生成假金红石(Fe2Ti3O9)、Fe2O3和金红石型Ti O2相,钛精矿球磨后颗粒细化,物相转变从更低的温度开始,同样温度条件下物相的转变也更充分;对球磨后的钛精矿进行800℃退火和105℃酸浸后,Ca O和Mg O的含量分别降低到0.089%和0.888%,除去率为88.7%和51.8%,而Ti O2含量从44.12%提高到53.64%,能够显著提高钛精矿的质量等级。     

攀枝花选钛厂提高钛精矿回收率的探索

针对攀枝花选钛厂原选别流程钛精矿回收率不高的问题进行了工业性试验研究，提出了原流程改进方案。采用降低重选精矿品位并加强磁选的方法，可提高最终电选钛精矿的回收率。     

Power Delivery from the Arc in AC Electric Arc Furnaces with Different Gas Atmospheres

The amount of heat supplied to the electric arc furnace affects the melting rate. Power delivery in a three‐phase EAF is influenced not only by the electric parameters such as arc length and voltage but also by thermal properties of the gases that form the plasma in the arc region. Application of the Channel Arc Model (CAM) suggests that power delivery is enhanced with long‐arc, maximum tap operation and plasma gases with high heat capacity. It is also suggested that foaming improves power delivery due to the presence of gases with high heat capacity.