湿法磨矿制备电工级硅微粉试验研究

该文选取某地石英尾砂(分级细砂)为研究对象,通过"磨矿—清洗—过滤"工艺流程的探索,主要考察磨矿时间、矿介比、介配比以及磨矿浓度对硅微粉理化指标的影响,最终确定电工级硅微粉的最佳制备试验条件。     

湿法磷酸萃取工艺对磷石膏晶形的影响

采用模拟湿法磷酸生产方式,通过控制萃取反应工艺条件来控制磷石膏晶形.采用扫描电子显微镜观察晶体形貌,采用激光粒度分析仪测定粒度分布和平均粒径.结果表明:液相中游离的H2SO4含量和P2O5含量对磷石膏的晶体形貌和大小都有影响,前者提高,二水石膏析晶过饱和度降低,磷石膏晶体由薄片状变为粗大的柱状和斜方六面晶体,然后再向聚晶转变,平均粒径变大;后者提高,二水石膏析晶过饱和度升高,晶体由粗大的板状变为柱状,然后再向细针状转变,平均粒径变小.反应温度升高,二水石膏析晶过饱和度降低,晶体尺寸变大,但晶体形状基本不变,均为柱状.从兼顾湿法磷酸生产和磷石膏建材资源化的角度出发,提出优化的萃取反应工艺条件为:液相游离H2SO4质量分数为5％,液相P2O5质量分数为15％～20％,反应温度为80℃,料浆液固比为2.5:1(质量比).     

A survey of heavy metals in municipal wastewater in combined sewer systems during wet and dry weather periods

During wet weather, combined sewer system overflows affect the quality of water in watercourses. For planning overflows, the lowest possible load of priority substances according to Directive 2008/105/EC is crucial and the knowledge of variability in concentrations of elements in the sewer system is necessary. The behaviour of heavy metals in a sewer system was observed in the course of dry weather flow (DWF) and wet weather flow (WWF). We found, from the comparison of concentration medians for the WWF and DWF that during wet weather periods, an increase in the concentrations of As, Cr, Cd, Pb, Mn and Fe occurs in the sewer system and the effect of nonpoint sources manifests itself. Zn, Cu and Ni concentrations decreased during wet weather periods, and Hg concentrations did not significantly change. During the WWF period, a considerable nonhomogeneity of the sewage system was demonstrated.     

湿法消化-氢化物原子荧光法测定植物提取物中镉的含量

探讨了应用原子荧光光法测定植物提取物中镉含量的方法。样品用硝酸+高氯酸混合液消化,在盐酸介质中,试样中的镉在镉专用2号试剂存在下,镉1号专用还原剂将二价镉还原成镉的挥发性组分,用AFS-8230原子荧光光度计测定。该法线性范围为0~60μg/L,相关系数r=0.9998,检出限为0.0024μg/L,相对标准偏差为1.36%,回收率为92.8%~96.1%。     

彩色聚氨酯皮革染料的制备与研究

以甲苯二异氰酸酯（TDI）、聚丙二醇（PPG1000）、2,2－二羟甲基丙酸（DMPA）、单硬脂酸甘油酯（GMS）、酸性红B等为主要原料,经自乳化法合成了一种彩色聚氨酯皮革染料,采用傅立叶红外吸收光谱分析证实了彩色聚氨酯染料的结构。研究发现聚氨酯染料和原染料相比,紫外－可见光谱图显示在200～250nm处的峰出现了38nm的红移;制备的聚氨酯染料乳液具有良好的冻融稳定性和高温稳定性,彩色聚氨酯膜具有较好的耐热性能和优异的耐干湿擦性能。     

Rheology of polyacrylonitrile‐based precursor polymers produced from controlled (RAFT) and conventional polymerization: Its role in solution spinning

Polymer solutions in dimethyl sulfoxide (DMSO) as a solvent, made from reversible addition fragmentation chain transfer (RAFT)‐mediated polyacrylonitrile (RAFT^¥ PAN) terpolymer with molecular weight (MW) of 260,000 g/mol and dispersity (Ð) of 1.29, behave differently under applied shear stress than polymer solutions made from conventional PAN (Control PAN) with similar MW (258,000 g/mol) but Ð of 2.05 in the same solvent. The unique rheology of RAFT PAN is because of the reduced amount of high MW polymer fractions. Specifically, a 25% (w/v) polymer solution of RAFT PAN had a viscosity of 198 Pas while the equivalent control PAN polymer solution had a viscosity of 968 Pas at a shear rate of 1 s^?1. Also, RAFT PAN polymer solutions had a longer Newtonian plateau than control PAN polymer solutions. This exhibits more liquid character in RAFT PAN polymer solutions than control PAN polymer solutions at same temperature and concentration. In dynamic tests, RAFT PAN polymer solutions gelled slower than their equivalent control PAN polymer solutions because of their longer polymer chain relaxation times. Slow gelling and higher liquid character in RAFT PAN polymer solutions can result in obtaining stronger and finer precursor fibers during wet spinning. Since RAFT PAN polymer solutions exhibit low viscosity and higher liquid character when compared to its equivalent control PAN at same concentration and temperature, these can allow a wider working window for wet spinning and can also allow higher solid content in the polymer solutions that remain easy to wet spin. This is expected to lead to compact and finer fibers with less voids and higher strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44273.     

湿法磷酸增产技改措施

针对云天化云峰分公司280 kt/a磷酸生产系统过滤和浓缩能力偏小制约产能发挥的问题,进行技改分析。通过新增消化槽、100 m~2转盘式过滤机,更换料浆泵和浓缩系统酸加热器,装置生产能力提高至320 kt/a,浓缩系统氟吸收率提升7~11百分点,达到了预期目的。     

Mathematical simulation of wet spinning coagulation process: Dynamic modeling and numerical results

A dynamic model of polymer wet spinning coagulation process is proposed in this article. The model is based on the double diffusion phenomenon, phase separation process, continuity balance, and momentum balance of the entire coagulation process. The uniqueness of the model lies in its dynamic feature. The model can simulate the system's dynamic response to variations in system inputs/parameters. Steady‐state system solutions can also be produced as the long‐time solutions of the dynamic model; a settling time can be observed at the same time. This paper employs a computationally efficient method of lines numerical algorithm for solving the dynamic model. A simulation experiment on a selected non‐solvent‐solvent‐polymer ternary system is carried out to verify the model as well as the numerical method. The dynamic simulation results are analyzed and discussed. At the end of the article, h‐refinement and p‐refinement are used to confirm the spatial convergence of the numerical solutions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3432–3440, 2016     

New Perspectives on the Gas–Solid Reaction of α‐Si3N4 Powder in Wet Air at High Temperature

The reaction behavior of chemically vapor‐deposited silicon nitride (α‐Si₃N₄) powder in wet air at 1673–1873 K for 10 h has been investigated. The oxidation and volatilization reaction coexist initially while volatilization reaction progressively becomes the limiting step with extended reaction time. Based on the experimental curves, a new kinetic model regarding both solid product layer and hypothetically volatile product layer has been developed to interpret its short‐term reaction and predict long‐term corrosion behavior. The calculated results agree well with the experimental data. Predictably, this new kinetic model can not only be used to treat the reaction of Si₃N₄ powder in wet air but also can be applied to deal with the gas–solid reaction of other ceramic powders.     

烷基化废硫酸再生工艺技术对比

通过对产品指标、尾气排放达标情况、投资、检修、长周期运行情况的对比,论述了国内、国际烷基化废硫酸再生技术的优缺点。