高温焙烧对含蛇纹石尾矿亚甲基蓝吸附性能的影响

富镁硅酸盐矿物蛇纹石具有比表面积大、天然卷曲结构、孔道结构丰富等特点,可作为优良的吸附材料。为实现蛇纹石资源的综合利用,通过高温焙烧方法对蛇纹石尾矿进行了改性研究,考察了焙烧蛇纹石尾矿对水相中亚甲基蓝的吸附性能。研究结果表明,与原矿相比,焙烧后的蛇纹石尾矿对亚甲基蓝具有较好的吸附效果,饱和吸附量约为11.27 mg/g;随着尾矿用量和吸附时间的增加,亚甲基蓝的吸附率也随之增加,且在中性和碱性条件下达到最好的吸附效果。焙烧后的蛇纹石尾矿对亚甲基蓝的吸附过程符合准二级动力学模型和Langmuir吸附等温线模型,吸附类型属于化学吸附,吸附方式为单分子层吸附。以上研究表明,高温焙烧利于蛇纹石尾矿对亚甲基蓝的吸附,可促进蛇纹石尾矿的综合利用。     

蛇形通道制备半固态A380铝合金浆料组织的演变

采用石墨质蛇形通道制备半固态A380铝合金浆料,并研究浆料制备过程中浆料组织的演变.结果显示,合金熔体在蛇形通道内发生一次凝固,在其通道内壁的激冷和异质形核作用下形成大量的初生自由晶,半固态浆料的剩余液相在收集坩埚内发生二次凝固形成二次非枝晶.初生晶粒的游离模型表明一部分初生自由晶直接生长为球晶,其他部分则成长为枝晶,枝晶在‘自搅拌’的作用下发生缩颈和熔断,通过‘自旋转’在蛇形通道内得到初步球化和熟化.二次凝固形成的二次非枝晶在收集坩埚内得到初步球化和熟化,同时初生晶粒在收集坩埚内得到进一步球化、熟化和均匀分布.     

Lead adsorption in a serpentine millichannel-based packed-bed device: Effect of hydrodynamics and mixing characteristics

The present study depicts the hydrodynamics and the mixing characteristics in a millichannel-based serpentine fixed-bed device to attain the particular demands of the miniature adsorption devices' fabrication. Residence time distribution analyses were accomplished to analyze the velocity distribution inside the packed bed geometry. The effects of operating variables on the system hydrodynamics and mixing and their impact on the lead adsorption characteristics were enunciated. New correlations were proposed for the frictional resistance and axial dispersion of the fluid. The parametric effects on the lead ions [Pb(II)] adsorption were studied in the same millichannel geometry packed with the graphene oxide coated glass beads. The kinetics of the adsorptive removal process is assessed by the Thomas model and the Yoon–Nelson model. The regeneration study of the said millichannel-based fixed-bed device was also executed.     

高硅水镁石钠化焙烧法除硅工艺研究

以高硅水镁石为原料、氢氧化钠为钠化剂,研究了高硅水镁石钠化焙烧除硅过程中氢氧化钠用量、焙烧温度、焙烧时间等对焙烧水洗产物中硅含量的影响,对不同温度条件下的焙烧产物和焙烧后水洗产物的结构和谱学特征进行分析和表征,以揭示高硅水镁石钠化焙烧除硅机理。结果表明：在焙烧温度为650 ℃、氢氧化钠用量为理论量3倍、焙烧时间为3 h的最优条件下,钠化焙烧过程中Na⁺会与蛇纹石热分解产物Mg₂SiO₄中的Mg²⁺发生置换反应,最终形成可溶性盐Na₄SiO₄,从而水洗除去,水洗产物中硅质量分数为1.89%,硅提取率达90.1%。     

A parametric comparison of temperature uniformity and energy performance of a PEMFC having serpentine wavy channels

Proton exchange membrane fuel cells (PEMFCs) are regarded as alternative energy sources because they are environment friendly and deliver no harmful emission. As its reliability and power generating efficiency is largely influenced by the temperature distribution, it is necessary to improve the temperature uniformity which is crucial in PEMFCs. To this end, this numerical study presents an attempt to optimize the flow channels via introducing wavy shape flow channels at the ribs. The numerical model is validated by experimental data available in the open literature. Two kinds of wavy shape flow channels are designed while straight flow channel is set as a reference. In the PEMFCs with wavy shape flow channels, the effects of the amplitude and wavelength on the thermal performance are simulated and analyzed. Results show that wavy shape flow channels provide better performance not only for thermal uniformity but also for PEMFC output power and efficiency. With lower amplitude and wavelength of wavy shape flow channels, the power can be promoted up to 3.69% and 7.26% for two kinds of wavy shaped flow channels compared with straight flow channel, respectively. The influences of amplitude and wavelength on the thermal uniformity and the output power are also analyzed. This paper provides a new insight to PEMFC flow channel designers.     

A study on nanofiller effects of serpentine in polypropylene matrix

The nanocomposite materials were prepared using serpentine as filler and polypropylene (PP) as the matrix in the presence of maleic anhydride grafted polypropylene (PP‐g‐MA) compatibilizer. The melt intercalation was carried out following serpentine modification with a quaternary salt of cetyl‐trimethyl‐ammonium bromide. The structure of nanocomposites was shown by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) studies. Thermal analysis performed by differential scanning calorimetry (DSC) demonstrated that the nanocomposites have higher percentage crystallinity when compared to neat PP. Dynamic mechanical analysis (DMA) revealed that the storage and loss moduli values of the nanocomposites are better than those of the matrix resin. Tensile properties of nanocomposites are significantly different from PP, e.g., the Young's modulus of the nanocomposite with 2 wt % serpentine and 6 wt % PP‐g‐MA (PP‐2,6Q) was found to be 2065 MPa, i.e., nearly 190.8% increase over the PP matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of modified flow field on optimal parameters estimation and cell performance of a PEM fuel cell with the Taguchi method

The study applies a three-dimensional model simulating the transport phenomenon and electrochemical reactions of full scale serpentine channels to determine the best arrangement of cuboid rows at the axis in the anode and cathode channels. With the best arrangement of the cuboid rows in the channels, the Taguchi methodology is used in the experiment to obtain the optimal operating parameters for three objectives with the minimum pressure drops in anode and cathode channels, and maximum electrical power. The results show that the interactions of flow fields between each cuboid and the current collector surface generate less overall deflection effect and force more reactant gases into the catalyst layer to have more uniform current density distributions. The electrical power is 30% greater for the three objectives optimization than for minimum pressure drops optimization and the pressure drops 275% less for the three objectives optimization than for maximum electrical power optimization.     

蛇纹石与绿矾耦合提取富镁溶液矿化二氧化碳并回收镍

蛇纹石与绿矾耦合提取镁用于矿化二氧化碳,并富集回收蛇纹石中的镍,这为处理蛇纹石和绿矾提供了一条新的路径。为得到富镁溶液,同时从溶液中分离镍,以蛇纹石与绿矾混合焙烧-浸出后得到的溶液为研究对象,采用水解沉淀法除铁,二乙基二硫代氨基甲酸钠(DDTC)络合法分离镍镁,得到镍的产物和富镁溶液并将其用于二氧化碳矿化。结果表明,该方法能够高效地去除杂质、分离镍镁。在30℃、p H为5.0条件下,铁的去除率达97.36%,而镍、镁的损失率较低。在最佳络合条件下,镍的络合率达到99.50%,而镁的损失率仅为3.03%。此外,对络合机理进行了研究,DDTC中的特征官能团是—SH,络合之后镍和铁分别以Ni[(C₂H₅)₂NCS₂]₂,Fe[(C₂H₅)₂NCS₂]₃的形式存在,而镁不会被络合。富镁溶液在80℃下矿化率达92.63%。每1 000 kg蛇纹石可固定227.38 kg的二氧化碳...     

徐州北矿金属循环利用研究院

<正>变废为宝追求资源利用极致创造价值实现客户企业共赢徐州北矿金属循环利用研究院(原徐州国贸稀贵金属综合利用研究所)成立于1978年,2010年4月兼并重组进入北京矿冶研究总院,更名为"徐州北矿金属循环利用研究院"。该院以有色金属二次资源循环利用为核心主业,包括技术研发、贵金属产品研制、工程咨询与设计和冶金环保技术与设备4大板块。还拥有具有独立法人的《中国资源综合利用》杂志社。目标是在5年内打造成为在有色金属循环利用领域国际一流的大型科技型企业,2015年营业收入达到10亿元。     

蛇纹石对黄铁矿浮选的影响及机理

通过浮选实验、沉降实验、显微镜下观测、接触角测试和吸附量实验,研究蛇纹石对黄铁矿浮选的影响,并对其机理进行分析。结果表明：矿物粒度在蛇纹石与黄铁矿的浮选分离中起着重要作用,比黄铁矿粒度小的蛇纹石颗粒能够通过异相凝聚作用吸附在黄铁矿表面,改变黄铁矿的表面性质,影响黄铁矿的浮选。机理研究表明：蛇纹石表面是亲水的且不吸附捕收剂戊黄药(PAX)。蛇纹石吸附在黄铁矿表面,降低了黄铁矿表面疏水性和戊黄药在黄铁矿表面的吸附量,使黄铁矿浮选回收率降低。增加戊黄药在黄铁矿表面的吸附量能够一定程度上恢复被抑制黄铁矿的浮选回收率,但蛇纹石用量较高时,黄铁矿浮选回收率仍降低。因此,微细粒蛇纹石通过异相凝聚作用在黄铁矿表面附着,降低黄铁矿表面疏水性是蛇纹石影响黄铁矿浮选的主要原因。