盐酸浸出机械活化和碳热还原钛铁矿制备纳米二氧化钛

采用一个新工艺来处理天然钛铁矿并制备高品位的人造金红石纳米颗粒.该工艺主要包括球磨、碳热还原和盐酸浸出步骤.天然钛铁矿通过球磨处理后,颗粒尺寸会大幅度减小;后续的碳热还原会导致高钛渣的形成.在盐酸浸出工序中,重点考察了酸浸时间、温度和酸的浓度对浸出过程的影响.通过优化工艺条件,最后所得到的产品为纯度超过98.0％、颗粒尺寸为10～200nm的TiO2纳米颗粒.     

机械活化和氧化-还原处理对攀西钛铁矿精矿盐酸浸出的影响(英文)

研究机械活化和氧化-还原处理对攀西钛铁矿精矿盐酸浸出过程的影响。结果表明:机械活化和氧化-还原处理均可明显提高钛铁矿精矿中铁、钙和镁的浸出;氧化-还原处理的钛铁矿经盐酸浸出后得到的人造金红石,其钙镁含量过高,不能满足沸腾氯化法的要求;经机械活化处理的氧化-还原钛铁矿,能进一步降低盐酸浸出渣的钙镁含量,所得到的人造金红石含TiO290.50%、全铁1.37%、钙镁总量1.00%,完全满足沸腾氯化法的生产要求。最佳的氧化还原处理条件为:在900℃氧气气氛中氧化15min,在750℃氢气气氛中还原30min。     

机械激活工艺对TiO2碳热还原合成纳米TiC的影响

以纳米TiO2/碳黑为原料,通过机械激活-碳热还原法合成纳米TiC粉末,研究了机械激活工艺对TiO2碳热还原反应的影响.产物经XRD分析表明,激活时间延长、球料比增大、球磨机转速加快都有利于促进纳米TiO2碳热还原反应进行得更完全,但最终TiC产物中(Fe,C)杂质含量也随之上升.综合考虑,球磨时间4～8h,球料比10:1,转速250r/min对后续碳热还原合成纳米TiC是较合适的工艺选择.     

机械力活化合成机制研究

用两种球磨方式活化氧化铝,用化学分析法测量氧化铝碳热还原反应后生成氮化铝的转化率,考察了球磨活化对氧化铝碳热还原反应合成氮化铝的作用,研究了机械力活化合成的机制。结果表明,氧化铝与碳粉混合球磨时对碳热还原反应的作用远小于氧化铝单元单独球磨时对反应的作用,经球磨活化后,氧化铝碳热还原的反应温度降低,两相复合结构机制不能合理地解释这一实验结果。本研究认为,球磨过程中晶粒尺寸细化至纳米级以及显微应变的存在是球磨化活化促进化学反应的主要原因。     

低温机械化学法制备Mo-Cu纳米复合粉末

以CuMoO4-MoO3粉末为前驱体,采用机械化学-氢气共还原的方法制备出Mo-Cu纳米复合粉末。通过DSC对前躯体的制备温度进行研究,通过XRD、SEM及TEM分别对粉末的相组成、形貌和粒度进行表征,从热力学的角度对粉末的还原过程进行分析。结果表明,机械球磨可以有效地降低粉末的颗粒尺寸,增大反应面积,提高粉末还原活性,从而在低温下制备出Mo-Cu复合粉末。通过优化工艺参数,对机械球磨15h的CuMoO4-MoO3混合粉末在680℃下还原,可以得到颗粒尺寸为50～100nm的Mo-25%Cu(质量分数)纳米复合粉末。     

机械活化-盐酸常压浸出钛铁矿的影响

采用机械活化-盐酸常压浸出法对钛铁矿进行了选择性浸出,研究机械活化对钛铁矿的结构、形貌、粒度及浸出效果的影响。结果表明,机械活化可以细化钛铁矿的粒径,增加颗粒表面的粗糙度,从而增大其比表面积;机械活化可以破坏钛铁矿晶粒的完整性,并产生大量晶格缺陷,使晶格膨胀,上述作用均能强化钛铁矿浸出。最优浸出条件为:盐酸质量分数20%,反应温度100℃,酸矿比1.2,钛铁矿活化时间2 h。最优条件下Ti和Fe的浸出率分别为1.07%和95.5%,最终Ti和Si富集在渣中,其他元素进入浸出液。将上述得到的富钛渣煅烧获得了品位高于90%的人造金红石。     

预处理方式对盐酸浸出钛铁矿制备人造金红石的影响

本文以钛铁矿精矿为原料,采用盐酸浸出制备人造金红石,首先采用Factsage 6.0热力学软件绘制了相关组分的φ-pH图,研究了盐酸浸出制备人造金红石的热力学基础;而后研究了还原焙烧和弱氧化焙烧两种预处理方式对人造金红石品位、粉化率等的影响。结果表明:在盐酸加压浸出体系中,钛铁矿中的FeO、Fe_2O_3、CaO和MgO均能溶解在溶液中,而SiO_2和TiO_2则留在固相中;还原焙烧和弱氧化焙烧预处理有利于提高产品TiO_2的品位,其中弱氧化焙烧还可降低产品的粉化率。     

球磨转速对碳热还原钛铁矿合成Ti(C,N)复合粉末性能的影响

在碳热还原钛铁矿合成Ti(C,N)复合粉末前的高能球磨预处理过程中,采用不同的球磨转速,研究了合成的Ti(C,N)复合粉末的粒径、形貌、物相组成、烧结性能和耐腐蚀性能。结果表明,随球磨转速从250 r/min增至750 r/min,Ti(C,N)复合粉末的粒径先减小后增大,烧结性能和耐腐蚀性能先提高后降低;与250 r/min相比,600 r/min时碳热还原钛铁矿合成Ti(C,N)复合粉末的烧结体抗折强度增加18.3%,断裂韧度增加48.7%,腐蚀电位正移253 m V。球磨转速优选为500~600 r/min。     

采用混合Nb_2O_5,B_2O_3和Mg粉末冶金法合成硼化铌（英文）

在强还原剂条件下,以相关的金属氧化物为原材料,采用粉末冶金法成功合成具有不同含量NbB、NbB_2和Nb_3B_4相的硼化铌粉末和单相NbB粉末。在室温下使用高能球磨机球磨Nb_2O_5、B_2O_3和Mg混合粉末。随后,利用HCl浸出除去球磨粉末中无用的MgO相,合成最终产物NbB-NbB_2-Nb_3B_4,产物在1500℃下退火4 h,以便观察硼化物之间的转换。采用XRD、DSC、PSA、SEM/EDX、TEM和VSM表征该产物。研究球磨时间(达9h)对产物形成、显微组织和热行为的影响。化学计量混合粉末经2 h球磨后,发生了还原反应。在不存在任何二次相和杂质时,通过机械化学法,球磨5 h并采用4 mol/L HCl浸出,得到高纯纳米尺寸NbB-NbB_2-Nb_3B_4粉末。经退火处理后,纯的纳米尺寸NbB-NbB_2-Nb_3B_4粉末转变为单相NbB,不存在NbB_2和Nb_3B_4相。     

醇热还原法制备纳米金属钌颗粒

报道了利用溶剂热工艺在乙醇溶液中制备胶态纳米金属钌颗粒的方法. 在120.℃热处理不同时间后, 观测到溶剂热还原反应形成不同颜色的中间体. 通过添加醋酸根稳定剂, 在乙醇溶剂中形成晶粒尺寸为3～6纳米的单分散金属钌颗粒. 通过该方法还合成了溴化十六烷基三甲铵(HTAB)包敷的晶粒尺寸为1～5纳米的金属钌粉体.     

Mechano-thermal reduction of molybdenite (MoS2) in the presence of Sulfur scavenger: New method for production of molybdenum carbide

In this research, carbothermic reduction of molybdenite in the presence of sodium carbonate as sulfur scavenger by mechanical activation and heat treatment was studied. Mechanical activation of the mixed powders of molybdenite, graphite and sodium carbonate with 1:4:2 mol ratios were carried out by ball milling process under argon atmosphere for 10,20,40,50 and 70 h. The X-ray diffraction (XRD) patterns of samples revealed that no reaction occurred in the mill even after 70 h of milling. In order to study the mechanism of carbothermic reduction of molybdenite in the presence of sodium carbonate, simultaneous thermal analysis (STA) under heating rate of 10, 15 and 20 °C/min was carried out on the activated samples. XRD patterns and thermodynamic analysis of reaction products indicated that carbothermic reduction of molybdenite in the presence of sodium carbonate was advanced through the formation of intermediate phases Na₂MoO₄, MoO₂ in which the final products were Mo₂C, Na₂S. For separation of these two products, leaching by HCl and hot water was used. The XRD patterns of leached products were shown that molybdenum carbide with high purity was produced. The kinetics of reduction reaction was investigated and it was found that mechanical activation lowered the reaction temperature and activation energy.     

钛铁矿直接制备Ti(C,N)复合粉的组织与特性

以钛铁矿(FeTiO3)为原料,用碳热还原技术制备含Fe-Ti(C,N)复合粉。用酸浸工艺对复合粉进行分离提纯,并对其物相进行定性分析,对其化学组成进行定量分析,对其物理特性(如形貌、粒度、比表面积)进行测试。结果表明,Fe-Ti(C,N)复合粉主要由Ti(C,N)、α-Fe组成,其中Ti(C,N)占50.25%,α-Fe占44.08%,粉体呈不规则形状,粒度约为2~3μm,比表面积为2.39 m2.g-1。酸浸分离的Ti(C,N)粉体纯度为97%,其性能指标已达到商品粉的要求。     

Effect of mechanical activation on the production of SiC from silica sand

In this study the effect of 100 and 200 h low energy ball milling on the carbothermic reduction of SiO₂ and C powder mixture was investigated. Microstructure studies of the mixture by SEM revealed that the particle size had been decreased and the SiO₂ particles had been covered by C particles due to the milling. The results of thermal analysis (TG-DTA) of milled and unmilled mixtures clearly showed that the reduction temperature decreased due to milling process. XRD pattern of 200 h activated mixture proved that β-SiC had been formed almost completely after reduction at 1500 °C.     

Direct carbothermic reduction of ilmenite concentrates by adding high dosage of Na2CO3 in microwave field

A clean and efficient route for the utilization of ilmenite concentrates was proposed by direct carbothermic reduction in microwave field. High dosage of Na₂CO₃, which can be recycled, was added to accelerate the reduction reaction of ilmenite concentrates. After microwave heating in the temperature range of 1073?1123 K for 20 min, the main products were Na₂TiO₃ and metallic Fe with the metallization ratios being as high as 92.67%?93.21%. The reduction products were processed by water leaching, ball-milling in CO₂ atmosphere and magnetic separation in turn. The final products after magnetic separation were Fe-rich materials and Ti-rich materials (90.04 wt.% TiO₂), which can be used to produce iron and TiCl₄ or TiO₂. The optimized heating temperature was 1123 K in terms of metallization ratios, magnetic separation and caking property of the reduction products. Besides, the reduction mechanism of ilmenite concentrates with the addition of Na₂CO₃ in microwave field was also proposed.     

In Situ Production of Fe-TiC Nanocomposite by Mechanical Activation and Heat Treatment of the Fe2O3/TiO2/C Powder

In this study, Fe-TiC nanocomposite was synthesized by carbothermic reduction of activated Fe₂O₃, TiO₂, and graphite powder mixture. The effect of 0, 5, and 20?h of high energy ball milling of mixture on the reduction process was also investigated. Comparing the results of the thermogravimetry analysis of milled and un-milled mixtures clearly showed that the reduction temperature decreased due to the milling process. XRD pattern of 20?h milled powder mixture proved that Fe-TiC nanocomposite was formed after the heat treatment of activated powder at 1100°C for 1?h under vacuum. The microstructure studies of the milled mixture by scanning electron microscope revealed homogenous distribution of TiC particles in the Fe matrix.     

综合利用钛铁矿制备二氧化钛、钛酸锂和磷酸铁锂

以钛铁矿为原料,经机械活化-盐酸浸出得到水解钛渣和富铁浸出液;用H2O2将水解钛渣中的Ti配位溶出,得到配位浸出液,并以其为反应物制备纳米级片状的过氧钛化合物;该过氧钛化合物经洗涤、煅烧制备得到纳米级片状的TiO2,其纯度高达99.31%(质量分数)。将过氧钛化合物与Li2CO3混合,球磨后煅烧合成性能优良的锂离子电池负极材料Li4Ti5O12。以富铁浸出液为原料,经选择性沉淀制备含少量Al和Ti的FePO4.xH2O,并以其为前驱体制备了Al-Ti掺杂的LiFePO4。该LiFePO4在1C和2C倍率下的首次放电比容量分别达151.3和140.1(mA.h)/g,循环100次之后容量无衰减。该方法也可用于钛白粉副产品硫酸亚铁的回收利用,制备性能优异的LiFePO4。     

MICROWAVE-ASSISTED CARBOTHERMIC REDUCTION OF ILMENITE

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表面机械活化粉煤灰提取氧化铝及其动力学研究

采用高能球磨活化粉煤灰,并对球级配、球料比、转速以及球磨时间进行正交试验,将经不同时间活化的粉煤灰与Na2CO3按一定比例煅烧溶出,得到Al2O3.通过测试分析,研究了高能球磨活化各工艺参数对Al2O3溶出率的影响,得到了最优化工艺条件,并对Al2O3溶出过程的动力学进行了验证分析.结果表明:当表面机械活化6h、溶出温度90℃、液固比L/S=6、硫酸浓度4 mol/L时,效益最高;此反应属于收缩未反应芯模型,表观活化能为60.87 kJ/mol,反应级数为0.1701.     

Preparation of titanium mineral from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching

Titanium mineral was prepared from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching. The leaching behaviors of elements like Fe, V, Mn, Al, Mg, Ca, and Si were highly related to the reduction degree. The phase compositions of the reduced materials and the leached residues were analyzed by XRD to identify the effect of reduction degree on the leaching mechanisms. The results showed that the concentrates were reduced to iron metal and titanomagnetite at 800?1000 °C for 0.5 h, and the above elements of Fe and impurities were easily leached. Deeper reduction led to the formation of ilmenite and Mg?Al spinel, which hindered leaching. Mg-bearing anosovite appeared in the further reduced materials, and the leaching rates of impurities became much lower. An upgraded titanium mineral with a normalized TiO₂ grade of 70.3% was achieved by H₂ reduction at 850 °C for 0.5 h and acid leaching, which is a satisfactory Ti resource for the preparation of titanium oxide by sulfate process.     

Kinetic study on carbothermic reduction of ilmenite with activated carbon

The carbothermic reduction of Panzhihua ilmenite with various additions of activated carbon was investigated by isothermal experiments over the temperature range of 1373 to 1773 K in the argon atmosphere. According to the reaction kinetics recorded by the infrared gas analyzer, it was found that the amount of carbon addition had little influence on the reaction rates at various temperatures except 1473 K. When the reaction temperature was above the eutectic temperature of 1427 K of Fe–C binary system, part of carbon would dissolve into Fe to form a liquid phase, which made the liquid Fe as a diffusion channel of carbon to diffuse to the reaction interface. The carbothermic reduction above 1573 K obeyed the shrinking-core model. The mass fraction of TiC could be determined by the standard addition technique.