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971.
972.
ABSTRACT In two different iron ore processing plants, it was demonstrated that when magnetite concentrate was filtered to prepare it for use as pelletization feed, the moisture that remained in the filter cake had greatly elevated levels of cations compared to the water removed by the filtration process. In particular, calcium concentrations in the filter cake were 565 times higher than in the filtrate water in Plant 1 and 19.4 times higher than the filtrate water in Plant 2. This effect is due to the adsorption of divalent cations on the magnetite surfaces resulting from electrostatic attraction when the pH of the solution is in the range where magnetite has a negative Zeta potential. Measurements of the Zeta potential as a function of pH for magnetite from Plant 2 determined that its point of zero charge (PZC) occurred at pH 3.0 to 3.5, which was much lower than is commonly reported in the literature and demonstrates that the PZC for magnetite is much more variable than is commonly thought. Plant experiments were carried out using carbon dioxide to reduce the pH of filter slurry so that the PZC could be approached. This was intended to allow adsorbed cations to be released from the magnetite surfaces during filtration. The pH adjustment was demonstrated to improve filtration rates by as much as 23%. 相似文献
973.
Jingjing Liu Wenlong Huo Bo Ren Ke Gan Yuju Lu Xiaoyan Zhang Xinyue Tang Jinlong Yang 《Ceramics International》2018,44(14):16751-16757
An innovative approach for fabricating porous alumina ceramics (PACs) with improved mechanical and thermal properties using walnut shell powders as pore-forming agent combined with alumina sol impregnation is reported in the present work. It is demonstrated that uniform distribution of spherical pores can be observed in as-prepared PACs by using above technical route. The decrease of walnut shell powder sizes significantly promotes the enhancement of crushing strength and reduction of thermal conductivity of the PACs. Meanwhile, the impregnated alumina sol is favoring for the formation of spherical micro-pores, then further improves their mechanical and thermal insulation performances. The lowest thermal conductivity and highest crushing strength of resulting sample reach 0.16?W/m?K and 29.2?MPa, respectively. This novel method offers new possibilities to fabricate high-quality PACs. 相似文献
974.
For the analysis of the adverse effects of smoke on health, it is essential to determine the amount and location of smoke particles deposited in the respiratory tract. However, the deposition characteristics of the particles are influenced by their morphology and size distribution. Moreover, the real-time particle size distribution during inhalation is important for determining smoke particle deposition in the lungs. Smoke particles generated under different fire conditions differ in their physical and chemical characteristics. Thus, there is a need to adopt international standard methods for characterizing the particles generated in fire. In the present study, the size distributions together with morphology of smoke particles were measured for each fire stage by using the steady-state tube furnace method given in ISO/TS 19700. The size distributions of smoke particles from wood and polypropylene (PP) were measured in real time by using an electric low-pressure impactor (ELPI+), and their morphologies were analyzed using transmission electron microscopy (TEM). 相似文献
975.
Aaron Robertson James Allen Robin Laney Alison Curnow 《International journal of molecular sciences》2013,14(7):14024-14063
Radon-222 is a naturally occurring radioactive gas that is responsible for approximately half of the human annual background radiation exposure globally. Chronic exposure to radon and its decay products is estimated to be the second leading cause of lung cancer behind smoking, and links to other forms of neoplasms have been postulated. Ionizing radiation emitted during the radioactive decay of radon and its progeny can induce a variety of cytogenetic effects that can be biologically damaging and result in an increased risk of carcinogenesis. Suggested effects produced as a result of alpha particle exposure from radon include mutations, chromosome aberrations, generation of reactive oxygen species, modification of the cell cycle, up or down regulation of cytokines and the increased production of proteins associated with cell-cycle regulation and carcinogenesis. A number of potential biomarkers of exposure, including translocations at codon 249 of TP53 in addition to HPRT mutations, have been suggested although, in conclusion, the evidence for such hotspots is insufficient. There is also substantial evidence of bystander effects, which may provide complications when calculating risk estimates as a result of exposure, particularly at low doses where cellular responses often appear to deviate from the linear, no-threshold hypothesis. At low doses, effects may also be dependent on cellular conditions as opposed to dose. The cellular and molecular carcinogenic effects of radon exposure have been observed to be both numerous and complex and the elevated chronic exposure of man may therefore pose a significant public health risk that may extend beyond the association with lung carcinogenesis. 相似文献
976.
Quantum chemical calculations have been employed to understand the nature of interaction between xanthate and Cu—as part of an ore and Cu—as part of a slag. A semi-empirical parameterized model, (PM3) is used to study ethyl xanthate, propyl xanthate, iso-propyl xanthate, iso-butyl xanthate and amyl xanthate. The total interaction energy, E, is interpreted in terms of the highest occupied molecular orbital (HOMO) energy of the individual collectors with copper ions. The electron density map along with the change in heat of formation, binding energy and dipole-moment, indicate that amyl-xanthate binds to surface of copper ions strongly in comparison to other xanthates. The numerical results obtained with potassium amyl xanthate also support the experimental data on recovery of copper values from a copper ore by flotation. 相似文献
977.
采用金相显微镜(OM)、扫描电镜(SEM)及其附带的能谱仪(EDS)和拉伸试验等技术研究了经搅拌铸造与真空重熔铸锭-挤压制备的Mg-Gd-Y-Nd/SiCP复合材料的显微组织与力学性能。结果表明,搅拌铸造法制备的铸锭经真空重熔凝固后,晶粒粗大,SiCP重新聚集,有利于排出搅拌铸造吸入的气体,这些组织特征对后续挤压棒材具有冶金遗传影响,使挤压棒获得更高强度。但较大的晶粒与第二相纤维组织降低了伸长率。SiCP颗粒会与Gd、Y元素反应生成REmSin相,但其不足以弥补因此而损失的Gd、Y元素的析出相强化,以及SiCP对杨氏模量的增强效果。 相似文献
978.
Polymer-nanoinorganic particles composite membranes present an interesting approach for improving the physical and chemical,
as well as separation properties of polymer membranes, because they possess characteristics of both organic and inorganic
membranes such as good permeability, selectivity, mechanical strength, thermal stability and so on. The preparations and structures
of polymer-nanoinorganic particles composite membranes and their unique properties are reviewed. 相似文献
979.
Presently, it has become an urgent and important concern worldwide to reduce the volume of waste and rationally use the waste for electric power generation. Sludge is a dominant part in the family of wastes. Drying of sludge, not only for volume reduction but also for further utilization, is becoming an essential and integral process. On the other hand, as the requirement of new materials production, for example, fine particles of micron or sub-micron scale for advanced materials, some new drying technologies and techniques have emerged. The market-pull may be the direct and active impetus to drying research and development (R&D). In this paper, drying technologies for sludges, fine particles, coatings as well as advanced dewatering are discussed to reflect the “hot” points of drying and dewatering R&D in Japan. And some novel dryers are also presented. 相似文献
980.
食盐加碘过程中,盐粒在接受碘液时通常处于堆积状态,这种方法存在着一些缺陷.文章对盐粒抛射运动轨迹进行了分析、计算和模拟,提出了采用盐粒处于抛射分散状态下接受碘液的方法.该方法使绝大部分盐粒具有直接碰到碘液的机会,同时,颗粒按大小顺序排列,颗粒愈大,接受到碘液的机会愈多.该方法也适用于其它流动性良好的颗粒与微量溶液的均匀混合. 相似文献