Co-precipitation of nano Mg–Y/ZrO2 ternary oxide eutectic system: Effects of calcination temperature

In the family of inorganic nanomaterials, zirconia is a highly promising functional ceramic with a high refractive index, hardness, and dielectric constant, as well as excellent chemical inertness and thermal stability. These properties are enhanced in nano-zirconia ceramics, because nanopowders have a small particle size, good morphology, and uniform and dispersive distribution. In this study, a co-precipitation process was proposed to synthesise highly dispersed MgO–Y₂O₃ co-stabilized ZrO₂ nanopowders. The effects of different calcination temperatures on the crystallisation degree and particle dispersion of zirconia nanopowders were characterised by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption using the Brunauer–Emmett–Teller (BET) theory, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). The optimum synthesis conditions were obtained as follows: 6 h of high-energy planetary grinding and calcination at 800 °C in an electric furnace. Under these optimum conditions, the average particle size of the prepared powder was 28.7 nm. This process enriches the literature on the controllable preparation of Mg–Y/ZrO₂ nanopowders obtained by the co-precipitation method.     

微波干燥软锰矿机理研究

采用微波加热法对软锰矿进行了深度干燥,考察了微波功率、物料质量、物料原始含水率、物料粒径等对其干燥效果的影响。结果表明物料在微波干燥180 s时达到最大脱水速率,且采用微波干燥在800 s时间内可将物料脱水至3.83%;原料质量一定时,随着微波功率的增大,有利于提高物料的脱水速率;微波功率一定时,在一定范围内增大物料质量和含水率,脱水速率就越快,干燥效果越好;物料粒径并非越小越好,反而大一些粒径的物料有助于物料加速脱水过程。     

硫粗精矿提质降杂试验研究

云南文山都龙多金属矿分选难度大,硫粗精矿中砷和杂质含量高,严重影响企业经济效益。在对硫粗精矿进行工艺矿物学研究的基础上,采用“磁选—深度细磨—浮选”的联合工艺对硫粗精矿进行提质降杂试验研究,并对锌进行回收。所得硫精矿中S、Zn、As品位分别为36.66%、2.72%、0.63%,其中S的回收率为75.73%,锌精矿中Zn品位为40.68%,回收率为52.63%。硫精矿的质量明显提高,提质降杂效果明显,同时还实现了锌的回收。     

Comprehensive recovery of the components of ferritungstite base on reductive roasting with mixed sodium salts,water leaching and magnetic separation

Ferritungstite ores have great commercial value because of the huge reserve and high content of W, Mo and Fe. But their economic recovery has long been a challenge due to its complex mineralogy and heterogeneous. The current study investigated how reductive roasting of ferritungstite ores with mixed sodium salts affected the phase evolution of W, Mo and Fe through Micro-area XRD and Powder XRD, with the goal of comprehensive transformation of ferritungstite. Reductive roasting with mixed sodium salts at 800 °C transformed ferritungstite to Na₂WO₄ and magnetite (Fe₃O₄), which were easily recovered by water leaching and magnetic separation. Furthermore, a lot of pores and gaps rather than sintering or agglomeration was observed in the ore particles after roasting by SEM-EDS, which was beneficial for the water leaching of W and Mo. As a result, 96.40% of W and 96.64% of Mo were extracted after water leaching, while an iron concentrate with an Fe content of 55.65% and recovery of 83.30% was obtained after magnetic separation. These results suggested such process would be applicable to the comprehensive recovery of valuable metals from ferritungstite ores, as well as similar tungsten ores and scraps.     

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery

Two α-MnO₂ crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO₂ prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO₂ crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO₂ crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO₂ material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO₂ material has better electrochemical performance.     

A new stable Cd(II)-framework for sensitive and selective detection of Cu2 + ions

A new water-stable 3D metal–organic framework (MOF), [Cd₂L₂]·NMP·MeOH (1, H₂L = 2-(3,5-dimethyl-1H-pyrazol-4-yl)-1,3-dioxoisoindoline-5,6-dicarboxylic acid, NMP = 1-methyl-2-pyrrolidinone) has been solvothermally synthesized and structurally characterized. 1 exhibits a 3D open-framework with a 2D metallic plane pillared by L^2 − fragments. Meanwhile, luminescent studies indicate that the luminescence intensity of 1 was strongly dependent on different metal ions. Most interestingly, 1 exhibited significantly quenching effect toward Cu^2 +, which implies that it may be used as a luminescent probe for the detection of Cu^2 +.     

民族类高校《化工基础》双语教学探索

化工基础是大学工科专业的一门重要的基础技术课程,也是理论到工程、基础到专业的桥梁。根据我校某一工科专业化工基础双语教学的实际情况,本文从双语教学的教材、内容、手段和考核方式等方面,对地方民族类高校化工基础双语教学进行了阐述。     

不对称故障下的IIDG改进功率控制策略

针对采用传统正序无功功率注入控制策略的逆变型分布式电源IIDG(inverter-interfaced distributed gener?ation)在电网发生不对称故障时无法有效支撑IIDG公共耦合点PCC(point of common coupling)电压的问题,提出一种改进功率控制策略.首先以预设相电压幅值...     

响应面优化芥末籽油的水酶法提取工艺及其脂肪酸分析

以芥末籽为原料,芥末油出油率为指标,首先确定最佳使用酶为碱性蛋白酶,通过单因素试验考察酶解温度、酶解时间和料液比等因素对出油率的影响,在此基础上,再结合响应面试验优化法,建立芥末籽油水酶法提取工艺并对芥末油进行脂肪酸分析。结果表明,碱性蛋白酶对芥末籽出油率的效果最佳;当加酶量为2.5%(g/100 mL)、酶解pH10、酶解温度为45 ℃、液固比为7:1 (mL/g)和酶解时间为6 h时,芥末籽出油率达到了23%,与预测值相差1.8%。采用GC-MS分析脂肪酸组分发现,不饱和脂肪酸相对含量高达81.34%,饱和脂肪酸相对含量为12.40%,油酸总含量高达50.72%,芥酸相对含量达到16.42%,二十碳-1-烯酸相对含量达到13.51%,本研究结果可为芥末籽油的综合开发与利用提供新的途径。