氮化镍钨加氢精制催化剂氮化过程的TG—DTA研究

通过对镍钨单金属氧化物、双金属氧化物、负载型金属氧化物和工业镍钨系列G1催化剂在氢氮混合气中还原氮化和钝化过程的TG-DTA原位实验,分别考察了反应温度、氢氮比、中间产物、助剂等因素对镍钨金属氧化物氮化历程的影响。结果表明,WO3可以在氢氮混合气中被还原氮化;氮化反应分两段进行;在氢氮体积比(4～5)∶1,反应温度650℃的条件下,WO3可以被还原为产物W2N;在不同氢氮比的混合气中氮化,WO3会生成不同的中间产物WO2和WOXNY,中间产物WOXNY进一步氮化生成W2N要比WO2容易;助剂Ni的加入使氮化反应温度降低了100℃;载体γ-Al2O3的加入使金属氧化物的氮化过程变为一步氮化还原反应。氮化产物W2N在通常条件下只会与空气中的氧发生表层氧化,而不会发生剧烈的氧化燃烧。因此,对于氮化产物W2N不必进行钝化处理。利用氮化处理技术,可以对现有工业催化剂进行氮化处理。     

Formation and recovery of Co,Ni, Cu macromolecular complexes with polystyrene and acrylic acid

The formation and structure of Co²⁺, Ni²⁺ and Cu²⁺ macromolecular complexes with a series of polystyrene and acrylic acid copolymers (PSt/AA) were studied. Both the copolymers and the metal complexes (M-PSt/AA) were characterized by FTIR, elemental analysis, Gel Permeation Chromatography and AAS. It is shown that the PSt/AA copolymer has rather strong coordination ability to the metal ions by chelation with the carboxylate group, and the microstructures of the M-PSt/AA complexes can be well controlled. Its adsorption behavior toward Co²⁺, Ni²⁺ or Cu²⁺ and various related parameters in the separation process were determined. The results indicate that the adsorption capability varies with pH and the maximum adsorption capacities were 337 mg/g for Co²⁺, 338 mg/g for Ni²⁺ and 341 mg/g for Cu²⁺ at around pH 7. Adsorption isotherms reveal that the adsorption process is consistent with the Freundlich equation. Experiments show that PSt/AA can recover Co²⁺, Ni²⁺ or Cu²⁺ with a high adsorption rate and high selectively coefficient from a simulated industry solution containing Ca²⁺ and Mg²⁺ as impurities. The resin can be readily stripped with acid and recycled for re-use after transformation to its sodium form.     

微晶氢氧化镍粉末的制备及性能

采用化学沉淀法制备氢氧化镍粉末,通过正交试验和单因素试验,得到反应的最佳工艺条件。以XRD和SEM分析了氢氧化镍粉体的相结构和形貌。结果表明,所制得的样品为-βNi(OH)2。对样品进行恒流充放电电化学性能测试表明,样品具有较好的放电性能,适合于作镍氢电池的正极材料。     

Leaching behavior of metals from a limonitic nickel laterite using a sulfation–roasting–leaching process

The leaching behavior of metals from a limonitic laterite was investigated using a sulfation–roasting–leaching process for the recovery of nickel and cobalt. The ore was mixed with water and concentrated sulfuric acid followed by roasting and finally leaching with water. Various parameters were studied including the amount of acid added, roasting temperature and time, sample particle size, addition of Na₂SO₄ and solid/liquid ratio in leaching process. More than 88% Ni, 93% Co and < 4% Fe are extracted under the determined conditions. Simultaneously, about 90% Mn and Cu, 70% Mg, 45% Al, 25% Zn, 4% Cr and Ca are extracted respectively. The pH of the leach solution is about 2. The leaching efficiency is independent of sample particle size due to decomposition of ferric sulfate formed during roasting. The roasted mass was characterized by various physico-chemical techniques such as DSC/TGA, XRD and SEM. This process provides a simple and effective way for the extraction of nickel and cobalt from laterite ore.     

黑镍除钴工艺的研究

黑镍是镍的高价氢氧化物,具有强氧化剂特性,在除钴过程还能深度净化铜、铁、锰、砷等杂质,是镍钴分离的一种好方法。本文研究了黑镍用量、温度、ｐＨ、溶液中钴浓度及黑镍中Ｎｉ￣（３＋）含量对除钴速度的影响。半工业试验和新疆阜康镍冶炼厂的工业实践表明,黑镍除钴工艺应用在硫酸盐体系中是可行的,除钴后溶液作为不溶阳极电积镍的阴极液,生产出的电镍完全符合１号电镍标准。     

某镍冶炼炉渣深度还原过程中的动力学分析

以某冶炼闪速炉渣和煤为原料研究了深度还原过程中的反应动力学。确定了反应温度和反应时间对铁还原速率的影响。试验结果表明,随着反应温度的提高和反应时间的延长,铁的金属化率在一定范围内逐渐增加并达到一极限值。建立了1200~1350℃下Fe O与碳反应的动力学方程,并计算了传质活化能。试验表明,炉渣与碳深度还原化学反应速率由Fe O从液态炉渣内部向反应表面的传质系数所控制,随着反应温度的升高,Fe O的传质系数逐渐变大,随着反应的不断进行,传质系数逐渐变小,反应的传质活化能为200~350 k J/mol。     

选择性沉淀法从堆浸液中分离回收铜镍

根据低品位堆浸液中杂质浓度高,而有价金属浓度低的实际情况,综合目前的一些处理技术,在大量试验的基础上提出了分步水解除铁,活性硫沉铜、硫化沉淀法沉镍的流程来回收分离铜镍。     

加入纳米Ni粉对微米级Fe粉试样烧结工艺及性能的影响

进行了真空状态下微米级Fe粉试样以及加入纳米Ni粉的微米级Fe粉试样的烧结试验。得出如下结论:添加1%纳米Ni粉的微米级Fe粉试样在900℃真空烧结2h的烧结体强度(289.61MPa)比微米级铁粉试样的烧结体强度(255.47MPa)提高13.4%。在保持烧结性能不降低的前提下,添加1%纳米Ni粉可使微米级Fe粉的烧结温度降低100℃或烧结时间缩短1h。     

不同预热温度WC增强镍基合金堆焊层的微结构演化与摩擦学性能

目的 研究不同预热温度(200、400 ℃)条件下硬质颗粒增强镍基合金堆焊层的微观组织结构演化机理,以及对其力学性能、磨损性能的影响规律。方法 采用等离子弧焊接技术在42CrMo钢基体表面堆焊硬质WC颗粒增强镍基强化层,利用X射线衍射(XRD)、扫描电子显微镜(SEM)、硬度计和摩擦磨损试验机,分析不同预热温度堆焊层的物相组成、微观组织形貌、力学性能和磨损性能,建立堆焊层制备工艺–微观组织结构–力学性能–磨损性能之间的强映射关系。结果 堆焊层主要由γ-Ni/Fe、WC、W2C、M7C3、M23C6、Ni2W4C、Cr3C2等物相组成,在预热温度200 ℃下堆焊层二次碳化物析出较少,发生了严重的WC颗粒沉降现象;在预热温度400 ℃下,堆焊层析出了大量的二次碳化物,WC颗粒沉降减弱,组织均匀性提高。在400 ℃下预热,相较于200 ℃下预热,堆焊层的磨损质量减少了51.85%,磨损率减少了51.89%。结论 高预热温度和长保温时间可促进WC颗粒界面反应,驱动大面积二次碳化物的析出,有效缓解WC颗粒沉降,改善凝固组织中WC颗粒的分布均匀性,从而显著提高堆焊层的硬度和耐磨性。     

几种合金在450℃/23MPa超临界水氧化环境中腐蚀行为研究

采用X射线衍射仪、扫描电子显微镜等分析手段,对比研究了4种典型镍基耐蚀合金在450℃/23MPa下Na₃PO₄、Na₂SO₄、NaCl超临界水溶液中的腐蚀行为。结果表明,50h后,合金表层均匀分布着短棒状、针状的腐蚀产物,主要组成为NiCr₂O₄,Cr₂O₃,NiO,Ni₃(PO₄)₂,CrPO₄和Na₃PO₄等。500h后,腐蚀层的厚度明显增大,依据腐蚀层厚度的增大速度,4种合金的耐蚀性顺序为：X-1#>X-2#>625>C-276。