转炉提钒工艺对钒渣质量的影响

分析了钒渣中影响后道工序提取V2O3的相关因素,并研究转炉提钒的特点对钒渣质量的影响,提出了相关的工艺改进思路。     

助磨剂对石煤提钒尾渣超细粉磨的影响

采用搅拌磨对钒尾渣进行超细粉磨,考察4种助磨剂的助磨效果,确定最合适的助磨剂为焦磷酸钠,对焦磷酸钠助磨产品的粒径分布、表面电位、表面吸附特性以及颗粒形貌等进行测定分析。结果表明,搅拌磨制备钒尾渣微粉的最佳参数为:添加焦磷酸钠质量分数为1.8%,矿浆质量浓度为1 g/mL,粉磨30 min,所得产品D_(50)=7.85μm、D_(90)=19.78μm,相比未添加焦磷酸钠的磨矿产品D_(50)、D_(90)分别减小了2.97、8.47μm,粉磨时间缩短至少10 min。焦磷酸钠通过在钒尾渣颗粒表面的吸附,增大颗粒的表面电位,减少微细颗粒在表面的粘附,降低矿浆黏度,从而提高钒尾渣的粉磨效率。     

V_2O_5掺杂ZnFe_2O_4复合薄膜的制备及气敏性研究

采用溶胶-凝胶法制备V2O5掺杂ZnFe2O4溶胶作为敏感试剂,通过浸渍-提拉法在锡掺杂玻璃光波导表面上制备V2O5掺杂ZnFe2O4复合薄膜,研制出V2O5掺杂ZnFe2O4复合薄膜/锡掺杂玻璃光波导气敏元件,对二甲苯、苯乙烯等挥发性有机气体进行检测。结果表明,该敏感元件对二甲苯气体具有较高的灵敏度、较好的重复性和选择性响应,能够检测到的最低气体浓度为1×10-6。该传感器具有灵敏度高、响应快、在室温下容易制备、结构简单等特点。     

高纯 Mgo-Cr_2O_3材料组成和结构对煤熔渣渗透的控制

高 Cr_2O_3含量的高纯 MgO-Cr_2O_3材料与煤熔渣的接触试验表明,接近 MgCr_2O_4化学计量组成,以 MgCr_2O_4和 Cr_2O_3为相结构的致密材料,抗煤熔渣侵蚀和渗透性俱优。MgCr_2O_4相与煤熔渣接触会慢慢分解,MgO 溶入渣中,Cr_2O_3在渣-耐火材料界面再结晶。     

Al_2O_3－MgAl_2O_4陶瓷的试验研究

在Ａｌ＿２Ｏ＿３中添加５－１５ｗｔ％ＭｇＡｌ＿２Ｏ＿４，采用热压注法制备Ａｌ＿２Ｏ＿３－ＭｇＡｌ＿２Ｏ４陶瓷。研究表明，Ａｌ＿２Ｏ＿３－ＭｇＡｌ＿２Ｏ＿４陶瓷具有良好的高温电阻率和抗熔渣－种子的腐蚀能力，经过进一步改进可望作为燃煤ＭＨＤ发电通道（半热壁型）阳极区电极间绝缘片材料。     

组成对R_2O-CaO-ZnO-Al_2O_3-SiO_2系统分相的影响

通过大量的配方实验和ＯＭ、ＴＥＭ观察,系统研究了Ｒ２Ｏ－ＣａＯ－ＺｎＯ－Ａｌ２Ｏ３－ＳｉＯ２系统分相与组成间的相互关系．研究结果表明,Ｋ２Ｏ比Ｎａ２Ｏ更有利于系统的分相,用Ｎａ２Ｏ等摩尔取代Ｋ２Ｏ时,分相区向低铝高硅区收缩．此外,系统分相区大小还明显受到ＺｎＯ、ＣａＯ相对含量的影响,高锌系统具有更为宽广的分相区．Ａｌ２Ｏ３对Ｒ２Ｏ－ＣａＯ－ＺｎＯ－Ａｌ２Ｏ３－ＳｉＯ２系统分相影响呈现出明显的反常现象．在ＺｎＯ含量为０．５５ｍｏｌ的系统中,当Ｒ２Ｏ由０．１０ｍｏｌＫ２Ｏ＋０．１０ｍｏｌ Ｎａ２Ｏ共同引入时,分相区大小和分相结构尺度都呈现出明显的铝反常现象,而Ｒ２Ｏ仅由 ０．２０ｍｏｌＫ２Ｏ引入时;仅分相结构尺度呈现出明显的铝反常现象,反常点的 Ａｌ２Ｏ３含量约为 ６．２０ｍｏｌ％．在一定的热处理条件下,适当增加 ＳｉＯ２的含量有利于系统分相,但当 ＳｉＯ２的含量过高时,分相将由连通结构逐渐转变为孤立相分布于连续基质相中的液滴状结构,甚至消失．     

α-Al_2O_3细粉含量对MgO系铸钛包埋材料性能的影响

在MgO系铸钛包埋料中加入α-Al2O3细粉,经1100℃热处理后,MgO和α-Al2O3可原位生成镁铝尖晶石,导致试样体积膨胀,显气孔率明显增加,耐压强度明显降低.当加入的α-Al2O3细粉为10%、20%(质量分数)时,α-Al2O3细粉几乎全部与MgO反应生成镁铝尖晶石,试样体积膨胀最明显,热膨胀率最大,可以很好地弥补钛铸件的冷却收缩.     

四价钒离子VO2+在几种阳离子交换膜中的自扩散行为

研究了VO2 在3种阳离子交换膜PE01,NF120以及Nafion1135中的自扩散行为,采用UV-3802可见-紫外分光光度仪测定VO2 浓度,建立浓度与时间的关系,用Ct=Ct∞(1-exp(-αt))经验方程拟合实验数据,得到VO2 在3种膜PE01,NF120以及Nafion1135中的自扩散方程.结合Fick扩散理论,推导出了VO2 在膜中的扩散系数D与方程中经验常数α的关系,计算出了VO2 在3种阳离子交换器Nafion1135,PE01以及NF120中的扩散系数分别为2.66×10-13,2.09×10-13和3.26×10-13m2/s.在所研究的阳离子交换膜中,PE01膜对VO2 具有最好的阻隔作用.     

B2O3对CaO-Al2O3-SiO2基连铸保护渣性能及结构的影响

采用热力学软件计算了Ca O-Al_2O_3-Si O_2三元相图和Ca O-Al_2O_3-B_2O_3-Si O_2四元相图。根据低熔点选择原则,确定了B_2O_3和Ca O-Al_2O_3-Si O_2渣系主要成分的具体含量。采用Brookfield旋转黏度计和DHTT-Ⅱ型熔化结晶温度测定仪对不同B_2O_3含量保护渣的熔化性能和结晶性能进行了实验研究。进一步采用分子动力学软件对熔渣进行模拟,分析了保护渣的微观结构,深入探讨了保护渣性能与结构之间的关系。结果表明,B_2O_3对Ca O-Al_2O_3-Si O_2渣系的黏度和转折温度有着重要的影响。当B_2O_3含量不高于9%时,保护渣的黏度和转折温度随着B_2O_3含量的提高显著降低。保护渣中B_2O_3含量的提高导致保护渣结晶孕育时间和完全结晶时间延长。相对于Al-O和Si-O配位结构,B-O配位结构最为稳定。体系中B离子可以代替Si、Al离子,形成B-O三配位结构与B-O四配位结构,体系结构由紧密的架状结构转变为松弛的层状结构,熔渣聚合度降低、黏度也降低。     

Cr2O3对Al2O3基渣系黏度的影响

铝热还原制备铜铬合金时,合金中会存在气孔以及Al2O3、Cr2O3等夹杂物,采用电渣重熔工艺可有效去除气孔及夹杂物等缺陷。采用内柱体旋转法测量了不同组成的CaO-Al2O3-Cr2O3、CaO-Al2O3-CaF2-Cr2O3渣系的黏度,采用XRD技术分析了高温熔炼渣的物相,并计算了各渣样的黏流活化能。研究结果表明,当碱度不变时,随着CaO-Al2O3中Cr2O3含量的增加,渣样的黏度逐渐降低。当Cr2O3含量为4%时,下降的趋势很大,当Cr2O3含量为2%时黏度下降趋势平缓,当渣系中Cr2O3含量较高时会出现Ca3Al2O6等高熔点相,造成渣黏度增大。CaO-Al2O3-CaF2-Cr2O3渣的高温黏度较低,1500℃时渣样的粘度均小于0.1Pa.s。渣系的黏流活化能变化趋势与渣样的黏度值变化趋势一致。     

Some physical properties of V2O5-Fe2O3 and V2O5-Fe2O3-Li2O systems

Various methods have been used to study the physical properties of the V₂O₅-Fe₂O₃ and V₂O₅-Fe₂O₃-Li₂O systems, including X-ray, electron microscope, Mössbauer effect, NMR and thermogravimetric measurements. The iron ions are approximately equally distributed in substitutional and interstitial sites in the V₂O₅ lattice. The maximum number of iron ions dissolved in the V₂O₅ matrix corresponds to 4 mol % Fe₂O₃. In all the samples a quantity of Fe₂O₃ which has not been included in lattice is observed. The V₂O₅-Fe₂O₃ and V₂O₅-Fe₂O₃-Li₂O systems are formed from solid solutions mixed with very small Fe₂O₃ particles. The analysis of the charge compensation of iron ions suggests that V₂O₅ is a quasi-amorphous semiconductor. Irradiation of V₂O₅-based samples with an electron beam induces the V₂O₅ platelets to convert to the VO _x phase.     

TiO2对CaO-Al2O3-CaF2渣系黏度的影响

采用内旋转圆柱法测量了不同组成的CaO-Al2O3-CaF2-TiO2渣系的黏度,采用XRD分析技术对高温熔炼渣的物相进行了分析,并计算了各渣样的黏流活化能.结果表明:当碱度不变时,随着CaF2的增加,渣样的黏度逐渐降低.当CaF2含量低于15%时,渣样黏度变化迅速;当含量高于15%时,渣样黏度变化平缓.当渣系中CaO含量较高时,会形成高熔点的Ca4Ti3O10、CaTiO3等相,造成渣黏度升高.渣系的黏流活化能变化趋势与渣样的黏度值变化趋势一致.     

Thermal studies on Cr-doped V2O3 crystals

Studies on heat capacity (C_p) of (Cr_xV_1?x)₂O₃ system, 0 ≤ x ≤ 0.12, revealed a sharp C_p anomaly in each composition in the range 150–190 K. With increasing temperature, the transition temperature at first increased from 173 K (x = 0) to 187 K (x = 0.033) and then decreased steadily to 151 K for x = 0.12. Similarly, the enthalpy of transition increased from 2025 J/mole for V_2.3O to 2355 J/mole-CrV₂O₃ for x = 0.02 and then decreased steadily to 1130 J/mole-CrV₂O₃ x = 0.12. 1 at. % Cr-doped samples exhibited an additional anomaly in the range 325–360 K. The C_p transitions may be correlated with corresponding electrical anomalies in the same temperature ranges. Our study on V₂O₃ failed to confirm the anomalies reported by Jaffray and Lyand.     

Phase equilibrium relations in the V2O3-La2O3 system

Phase equilibrium relations in the V₂O₃-La₂O₃ system were investigated by X-ray powder diffraction and metallographic techniques. Binary mixtures, prepared from high-purity V₂O₃ and La₂O₃ powders, were equilibrated at 1600° C and then arc-melted under a partial pressure of argon. The specimens were heat-treated at various predetermined temperatures for prolonged periods and the phases present were identified by reflected-light microscopy and X-ray powder diffraction. The system consists of only one binary compound LaVO₃. A eutectic between V₂O₃ and LaVO₃ was established at 1750° C and 19 mol % La₂O₃ and also between LaVO₃ and La₂O₃ at 1765° C and 75 moi % La₂O₃. No appreciable solid solubility was detected in the system.     

X-ray photoelectron spectroscopic studies of evaporated V2O2and co-evaporated V2O5/B2O3 films

X-ray photoelectron spectra of evaporated V₂O₅ and co-evaporated V₂O₅/B₂O₃ thin films have been investigated. The photoelectron spectrum of a simple V₂O₅ film shows the splitting of the V 2p level in accordance with the spins. The values of binding energies corresponding to V 2p and O1s are comparable with those reported previously. For co-evaporated V₂O₅/B₂O₃ films a chemical shift in the O 1s level has been observed which has been attributed to the changed chemical environment of oxygen as a result of the presence of boron and vanadium atoms. The values of binding energies for V 2p_3/2 and O 1s corresponding to simple evaporated V₂O₅ and co-evaporated V₂O₅/B₂O₃ show the presence of V₂O₄ species in the films.     

Structural studies of some V2O5-P2O5-B2O3-Fe2O3 glass systems

X-ray diffraction and infrared measurements were performed on vanadium borophosphate glass containing different amounts of iron ranging from 0–7.5 mol % and heat treated at 300 °C for various times. The structure and phase separation could be determined for each glass composition. V₂O₅ was the main precipitated phase in all heat-treated samples, and its amount was dependent on the heat-treatment time and Fe₂O₃ content. Also FeP was detected in samples heat treated for 24 h. The infrared measurements showed the presence of both V⁴⁺ and V⁵⁺. The symmetry of V₂O ₇ ⁴⁻ and VO ₄ ³⁻ groups was found to increase with increasing Fe₂O₃ content. It was also found that some PO₄ changed to BO₃, forming a non-bridging oxygen.     

Synthesis and photoelectric properties of V3O7 x H2O and V3O7, nanobelts

V3O7 x H2O nanobelts have been synthesized via a hydrothermal route. Monoclinic V3O7, nanobelts could be obtained by thermal decomposition of V3O7 x H2O nanobelts at 400 degrees C. The synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. It was found that the V3O7 x H2O is of orthorhombic phase and single crystalline nanobelts with width of 100-500 nm and length up to 100 microm. The formation mechanism of the V3O7 x H2O nanobelts was discussed. Light sensitivity in exposure to a simulated sunlight in different intensity and biases have been investigated on the electrode made from the V3O7 x H2O and V3O7, nanobelts. The results show that the photocurrent intensity of the V3O7 nanobelts is much larger than that of the V3O7 x H2O nanobelts. The fast current response has been observed under alternative control of light on and off at 2 s interval.