Vanadium sesquisulfide and its properties

Summary A study was made of the preparation of vanadium sesquisulfide by the technique of sulfidizing metallic vanadium powder with hydrogen sulfide. The stability of vanadium sesquisulfide in various media and its oxidation resistance were investigated.Translated from Poroshkovaya Metallurgiya, No, 2 (50), pp. 6–7, February, 1967.     

Characteristics of coreduction of nickel and molybdenum from oxide systems

We have studied the kinetic characteristics of reduction of nickel and molybdenum from their oxide mixtures. We have monitored the development of the specific surface area during reduction. We calculate the nucleation rate and the apparent activation energy. The reduction temperature for molybdenum in the presence of nickel was shown to decrease appreciably; and unlike the conventional scheme, in which during the first reduction stage MoO₃ transforms into MoO₂ or molybdenum suboxide, metallic molybdenum appears. Such reduction conditions made it possible to produce fine (S_sp=20 m²/g) powder of the nickel-based solid solution and pure molybdenum from the oxide mixtures precipitated from the salt solutions at 650°C.Institute of Materials Science, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5/6, pp. 52–56, May–June, 1995.     

The recovery of molybdenum from leach solutions by reduction

The feasibility of reductive precipitation of molybdenum oxides for molybdenum recovery from hypochlorite leach solutions has been investigated. Hydrogen gas at elevated temperature and pressure and hydrazine hydrate were used as reductants. The results are interpreted in terms of the behavior of mixed valent molybdenum polyanions.     

Silver recovery from spent silver oxide button cells

The present work investigates a hydrometallurgical process for silver recovery from spent silver oxide button cells. The effects of acid concentration, reaction temperature, reaction time and shaking rate on the silver dissolution are investigated in detail. In addition, an investigation regarding the dissolution kinetics of silver is undertaken, and the activation energy is found to be 26 kJ/mol. Silver is selectively precipitated as silver chloride using potassium chloride solution, ensuring that other impurities remain in the solution. Silver chloride is subsequently reacted with metallic zinc powder in 1.0 M HCl to yield metallic silver of 99.99% purity. The process is proven to be easy, straightforward and environmentally friendly.     

Reduction kinetics of molybdenum oxide in slag

The reduction rate of Mo oxide in slag by iron-carbon melt under different stirring conditions, reaction temperatures and slag composition has been investigated. Results indicate that the reduction of Mo oxide is a fast reaction; both stirring and temperature have evident influence upon the reaction; while the initial concentration of Mo oxide and content of fluoride in slag have also some influence upon the reaction. The reduction of Mo oxide is an apparent first order reaction. At 1440–1500°C, the reduction rate of Mo oxide is mainly controlled by Mo transfer in slag, with its diffusion activation energy of 223 kJ/mol. At 1500–1590°C, the transfer of Mo in metal turns to be the main limiting step, with its diffusion activation energy of 81.5 kJ/mol.     

一维氧化钼纳米材料的研究进展

一维氧化钼纳米材料具有优异的电学性能、电化学性能、场发射性能和气敏性能,在催化剂、传感器、平板显示器、智能窗、电池电极等领域显示了广阔的应用前景;其主要制备方法有水热法、气相沉积法和模板法.该文在综述了一维氧化钼纳米材料的制备方法、性能及应用的研究进展之后,指出了当前制备方法中存在的问题,并展望今后的研究重点是如何将一维氧化钼纳米材料应用于实际.     

Structural mechanism and character of redistribution of tungsten and molybdenum in their reduction from a mixed oxide

Conclusions At temperatures of 600°C and higher the mixed oxide (W_0.5Mo_0.5)O₃ is reduced with the starting uniform distribution of tungsten and molybdenum being retained in the end product, which is due to a single mechanism being operative in the process. As a result, a virtually homogeneous alloy is formed. At 400–600°C the reduction of tungsten and molybdenum from the mixed oxide involves two different structural mechanisms, which brings about a regrouping of the metals, disturbs their uniform starting distribution, and hence lowers the degree of homogeneity of the end product.Translated from Poroshkovaya Metallurgiya, No. 3(255), pp. 1–7, March, 1984.     

含金氧化钼矿石选矿试验研究

某含金钼矿石,钼氧化率高达68.5%。对该矿石采用优先浮选辉钼矿,将金富集到硫化钼精矿中,然后再浮选氧化钼矿物,硫化钼精矿经脱药抑制辉钼矿后氰化浸出回收金的工艺流程,使矿石中钼和金得到综合回收。选冶试验指标为:原矿钼品位0.52%,金1.53g/t,硫化钼精矿品位44.38%,氧化钼精矿品位23.6%,钼回收率78.2%,金回收率57.81%。     

含钼废渣冶炼钼铁的优化试验

利用含钼废料钼酸钙为原料,采用碳还原法冶炼钼铁,通过单因素分析试验及正交试验优化得出最佳的试验条件,钼酸钙加入量应低于10%,熔炼温度为1 525 ℃,保温时间为25 min,碱度为1.3。通过XRD、SEM、EDS分析得出用此方法生产得到的钼铁合金中,钼以Mo₂C、Fe₃Mo以及Fe₃Mo₃C的形式存在,渣系为二元玻璃渣系,具有与普通玻璃相似的成分系统。经测定合金中钼的回收率大于99%,钼资源回收效益可观。     

电解提取-X射线荧光光谱法测定钢中氧化物夹杂分量

研究了应用X射线荧光光谱仪的微区分析功能测定钢中氧化物夹杂分量的方法。优化了电解提取氧化物夹杂及X射线荧光光谱测定其分量的条件,同时建立了分析方法。实验结果表明,试样在弱酸性电解液并控制电流密度为0.02~0.06 A/cm2的条件下进行电解效果较好,测得氧化物夹杂总量一致。实验确定用X射线荧光光谱仪微区测定氧化物夹杂分量的最少样品量为不少于3 mg。用本法测定样品中氧化物夹杂分量SiO2,Al2O3,CaO,MgO,MnO2,Fe2O3,TiO2,Cr2O3的准确度(σ)为0.096%~0.63%,相对标准偏差小于6%,检出限为0.003×10-6~0.025×10-6。     

Inhibition of nitric oxide synthase slows heart rate recovery from cholinergic activation

The role of nitric oxide (NO) in the cholinergic regulation of heart rate (HR) recovery from an aspect of simulated exercise was investigated in atria isolated from guinea pig to test the hypothesis that NO may be involved in the cholinergic antagonism of the positive chronotropic response to adrenergic stimulation. Inhibition of NO synthesis with NG-monomethyl-L-arginine (L-NMMA, 100 micro M) significantly slowed the time course of the reduction in HR without affecting the magnitude of the response elicited by bath-applied ACh (100 nM) or vagal nerve stimulation (2 Hz). The half-times (t1/2) of responses were 3.99 +/- 0.41 s in control vs. 7. 49 +/- 0.68 s in L-NMMA (P < 0.05). This was dependent on prior adrenergic stimulation (norepinephrine, 1 micro M). The effect of L-NMMA was reversed by L-arginine (1 mM; t1/2 4.62 +/- 0.39 s). The calcium-channel antagonist nifedipine (0.2 micro M) also slowed the kinetics of the reduction in HR caused by vagal nerve stimulation. However, the t1/2 for the reduction in HR with antagonists (2 mM Cs+ and 1 micro M ZD-7288) of the hyperpolarization-activated current were significantly faster compared with control. There was no additional effect of L-NMMA or L-NMMA+L-arginine on vagal stimulation in groups treated with nifedipine, Cs+, or ZD-7288. We conclude that NO contributes to the cholinergic antagonism of the positive cardiac chronotropic effects of adrenergic stimulation by accelerating the HR response to vagal stimulation. This may involve an interplay between two pacemaking currents (L-type calcium channel current and hyperpolarization-activated current). Whether NO modulates the vagal control of HR recovery from actual exercise remains to be determined.     

利用气溶胶浮选技术提高某铜钼矿混合浮选钼回收率

以煤油作为辉钼矿的主要捕收剂,以气溶胶形式进行加药,进行了煤油用量实验、浮选时间实验、pH值和磨矿细度影响实验,研究采用气溶胶浮选技术提高某铜钼矿钼回收率.气溶胶浮选技术可使铜钼混合浮选阶段钼回收率提高3%,且浮选时间缩短20%左右;在相同的回收率下,气溶胶浮选法使用的煤油用量可节省40%;气溶胶浮选的最佳磨矿细度为0.074mm占65%,浮选矿浆最佳pH值为9.与传统浮选工艺相比,气溶胶浮选技术具有浮选效率高、药剂用量少等特点,在低品位难选矿石浮选方面具有一定优势.     

Liquid extraction of rhenium(VII) and molybdenum(VI) with trialkylphosphine oxide from acidic solutions

The liquid extraction of rhenium(VII) and molybdenum(VI) ions from sulfuric, hydrochloric, and nitric acid media is studied in the temperature range from 20 to 40°C using trialkylphosphine oxide in kerosene as an extracting agent. The maximum separation of these metals is attained when they are extracted from solutions of 1.0–2.0 M H₂SO₄ (the duration of intense phase mixing was 3–5 min). The enthalpy of the studied process is estimated to be ΔH = ?32.32 kJ/mol for molybdenum and ?51.52 kJ/mol for rhenium. The chemical aspects of the extraction process studied are discussed.     

氧化铁粉的回收与再利用技术探讨

从环保角度出发,介绍了钢铁企业酸再生产线对热轧钢板酸洗后形成的废酸循环利用及氧化铁粉制备和应用过程。通过技术优化和创新,不断提高产品品质和用途,并逐步满足了高端客户对氧化铁粉的不同品质需求,有效提升了酸再生能力和氧化铁粉一级品率,减轻了钢铁企业副产物对环境的影响。在现代企业生产过程中,提高固废资源利用效率,逐步实现资源化利用,减少环境污染,降低运营成本,形成绿色循环和可持续发展理念,成为时代发展的主题,也是企业应尽的社会责任。