气相色谱—质谱联用法对电子气中痕量氟化物的定性与定量

使用气相色谱—质谱联用法,采用全扫描模式,采取提取特征离子的方式对原始谱图进行处理,建立了电子气中微痕量氟化物杂质的定性、定量方法。检测限低、灵敏度高,单次进样,便可实现对多种氟化物杂质的定性和定量,且不受主成分的影响,是分析电子气中微痕量氟化物杂质高效精确的分析方法。     

空分设备基础知识讲座 第二讲 空气分离与空分设备流程(下)

本讲介KFS-120型、11－800型、150型、50型、全低压型等典型工艺流程,并介绍了工艺流程中制冷、杂质净除、精馏、换热等系统的组织。图5参4。     

空分设备基础知识讲座 第三讲 空气净化设备(一)

本部分为机械杂质的净除,讲了过滤器捕集尘粒原理、过滤器的性能指标、过滤器的分类,并介绍了拉西哥环式、干带式、袋式、膨胀机前后等的过滤器。图10表1。     

探索大修渣除氟除氰工艺

电解铝大修渣中,氰化物及氟化物含量超标,属于危险废物.通过实验研究了漂白粉作为除氰剂,氢氧化钙作为除氟剂时,大修渣的球磨粒径、液固比、除氰剂及除氟剂用量、反应时间、温度对除氰除氟效果的影响.试验结果表明:大修渣的球磨粒径越小,溶出氰化物及氟化物含量越多;液固比对大修渣溶出的氰化物及氟化物影响不大;漂白粉与大修渣的最佳用...     

OH^-对掺Er^3＋/Yb^3＋钡镓锗玻璃发光的影响及除水研究

钡镓锗玻璃是一种优质的红外发光材料,而钡镓锗玻璃中少量OH-的存在严重影响玻璃的结构并劣化了玻璃的发光性能.实验研究了在原料中引入氟化物除水和在引入氟化物的基础上进行反应气氛法除水两种方法对Er3+/Yb3+共掺钡镓锗玻璃上转换发光、1.53μm发光的影响,采用Frster-Dexter半经验简化模型分析了OH-和Er3+之间的能量转移几率.结果表明:在引入氟化物的基础上进行反应气氛法除水可以将玻璃中的OH-浓度降低到原来的1/11;随OH-浓度的降低,上转换荧光比1.53μm发光增强更明显,545nm绿光增强了2.8倍;OH-和Er3+之间的能量转移常数为1.75×10-19cm4/s,该值比磷酸盐玻璃中OH-和Er3+之间的能量转移常数稍大.     

某些氟化物的升华提纯

ＡｌＦ２在１１００℃升华时，因其蒸汽压和过滤金属氟化物杂质相近，升华分离比较困难，本工作采用较快速度升温和移动凝华区的办法，能满意地把带红棕色的ＦｅＦ３、ＣｕＦ２等杂质分离，得到含铁量〈１ｐｐｍ的无色ＡｌＦ３晶体。对ＢａＦ２、ＬａＦ３等高沸点氟化物原料，在１３５０℃升华时，能有效地除去过渡金属氟化物杂质。在氟化物玻璃中，存在Ｆｅ＾２＋Ｆｅ＾３＋的平衡，其中Ｆｅ＾３＋，其中Ｆｅ＾３＋从可见区到近红外     

用深冷法精制合成氨的合成气

引言供合成氨反应用的合成气中,如果含有氧化物、硫化物等杂质,就有害于合成氨触媒,而妨碍催化过程的进行。混杂在合成气中的各种杂质,一氧化碳较难除净。但是,反应压力在350大气压以下的合成氨工艺,对合成气中有害杂质的允许含量提出了很严格的要求,其中一氧化碳的含量必须降低到0．0035%(体积,以下皆同)以下。     

金属包装制品含氟废水处理技术改造研究与实践

针对铝制二片罐清洗工艺中氟化物废水处理效率不高、处理结果不稳定的问题，提出了一种分流式的处理方法。通过对源头的氟离子排放摸排，实现制罐废水中含氟废水的分流处理，高氟离子水流经化学沉淀除氟工艺处理，符合排放标准的水直接流入调节池，降低了除氟设备的负载，提升了除氟工艺的稳定性。详细阐述了该技术改造的原理、设计方案、优势及其应用效果。     

空分设备基础知识讲座 第三讲 空气净化设备(五下)

本讲为空分设备中的防爆措施。主要有采用液相、气相吸附净除碳氢化合物;采用排放液氧排除主冷液氧中的碳氢化合物;以及爆炸危险杂质的控制。图15表6。     

多晶硅冶金法除磷的研究进展

磷是多晶硅中的一种主要杂质元素,目前国内外采用冶金法除磷的工艺主要包括酸洗除磷、合金定向凝固除磷和真空除磷工艺.其中,酸洗除磷工艺可以很有效地去除磷杂质,但仍未达到太阳能级多晶硅小于0.1×10-4%(质量分数)的要求.采用合金定向凝固工艺可以去除80%以上的磷杂质,但目前对凝固后硅中残留溶剂金属的去除方法还有待进一步的研究.通过真空感应熔炼实验已将磷含量从15×10-4%(质量分数)降低至0.8×10-5%(质量分数),并对除磷的热力学条件进行了初步探索.     

Applicability of selected methods and sorbents to simultaneous removal of siloxanes and other impurities from biogas

This paper critically reviews and discusses the state-of-the-art technologies for the removal of siloxanes from biogas, which could be used to simultaneously remove other contaminants. The reasons for purifying biogas, the scope of this purification and the recommended (depending on the biogas utilization equipment) concentrations of volatile silicon-organic compounds are presented. Established and new promising methods of removing typical methylsiloxanes from biogases from municipal landfills and sewage sludge are characterized and analyzed. Their suitability for the simultaneous removal of other trace biogas impurities and possibilities of regenerating the spent sorbent are assessed. It is shown that the commonly used activated carbon is not suitable for comprehensive biogas treatment. On the basis of the analysis, an adsorption method using halloysite (a natural zeolite mineral) as an inexpensive, universal and regenerable adsorbent is proposed. The method can be used after physicochemical treatment to comprehensively purify biogas from methylsiloxanes, hydrogen sulfide, ammonia, halides and other technically and environmentally burdensome impurities. Some directions for further research in this regard and possible environmentally safe ways of utilizing the spent sorbent are indicated.     

氪氙浓缩物中有害杂质的清除

简介氪氙浓缩物中有害杂质的特性和危害,详细介绍在净化氪氙浓缩物过程中提高过程安全性和有效性的新方法,并通过流程实例作了具体分析与总结。     

Polar liquids: A survey of purification,conduction mechanisms,and interfacial effects

Interest is reviving in the dielectric properties of liquids. The present paper is concerned with a specific group of polar liquids having electrical conductivities which lie in the intermediate range between those of insulating oils and those of liquids such as electrolytic solutions.It has been found recently that ion exchange techniques provide a powerful means of purifying polar liquids. In this way, liquids have been deionised so effectively that their resistivities have been increased by three orders of magnitude as compared with previously published values.Published work on this subject is summarised. Removal of trace impurities from liquids may help to clarify mechanisms of electrical conduction, charge injection, and charge exchange phenomena in polar liquids.Preliminary results of investigations made by the authors are included in the article.     

高纯六氟化钨的制备技术研究进展

随着电子工业迅速发展,六氟化钨被广泛应用于半导体行业,其需求量日益扩大,对其纯度要求也越来越苛刻。综述了现有六氟化钨最常用的制备及纯化方法,分析了这四种纯化方法各自优缺点。在实际生产中,应根据六氟化钨中所含杂质的种类,联用多种纯化方法来获得高纯六氟化钨产品。此外,应尽早实现高纯六氟化钨工业化生产,填补国内相关领域空白。     

Purifying multicrystalline silicon by directional solidification method with induced electromagnetic field

Abstract

As an improved directional solidification (DS) method, the complex directional solidification (CDS) method is used for purifying and preparing multicrystalline silicon ingot in this experiment. The induced electromagnetic field is imposed to control refining and solidification process. An integral silicon ingot with the diameter of 130 mm, the length of 130 mm and the weight of 4 kg is successfully fabricated in a self-designed CDS furnace. Metallographic analyses reveal that the direction of the most grains is parallel to the axial of silicon ingot. Analyses proved that the distribution of impurities in the cross-section is more homogeneously, the distribution in axial is improved and the effective length of silicon ingot is increased. Theoretical calculations indicate that the effect of solidified rate on the removal of impurities is limited and the impurities can be removed effectively after more than two times directional solidification process.     

Preparation of CaF2 precursors for laser grade crystal growth

The expansion of commercial excimer lasers has increased the need of high-quality optics manufactured from CaF₂. The key technical parameters, affecting the long-term quality of CaF₂ excimer laser optics, are controlled by the purity of the raw material. The new purifying techniques provide 99.99% purity of the starting material which rises up to 99.999% into the grown crystals. However, the techniques are rather expensive which leads to a significant rise in the price of the final crystal product. The present paper describes an alternative highly effective and relatively low-cost technique providing a precise control over a set of preparatory and purifying procedures and crystal growth. Using an original apparatus for electro-chemical grinding of the thermo-broken starting material, the grained product, uncontaminated by unintentional impurities, may be highly purified by two complementary methods to produce precursors used for UV- and laser-grade CaF₂ crystal growth. Received: 20 April 1999 / Reviewed and accepted: June 2, 1999     

Purification of cadmium up to 5N+ by vacuum distillation

Cadmium was refined by vacuum distillation, a technique suitable for low boiling and melting point materials, to remove the heavy and low vapour pressure impurities at ppm level. The detailed analysis of the purified Cd as well as raw Cd was done by ICP-OES techniques for 27 impurity elements. Purification was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 3N+ purity indigenous cadmium to 5N+ (99.999%). Analysis confirmed the reduction of total impurity content from 134 ppm (3N7) for raw Cd to 3 ppm (5N7) upon vacuum distilled Cd. The present study shows that the analysis of impurities such as Fe, Mg and Ca are contributed from environmental effect, whereas impurities such as Pb, Bi, Ag, Ni, Cu, Zn and Tl require adaptation of elemental analysing technique to counter dilution effect. The Hg trace analysis can however be carried out by hydride generation techniques.     

冶金硅中杂质相存在形式研究

详细研究了工业硅中杂质存在形式及分布。工业硅中多数杂质偏析在硅晶界,组成深浅不同的杂质相,组分能谱分析证明颜色差异由铁、钛、铝、硅含量不同造成。白色区域是富Fe-Al-Si合金相,其中铁、硅含量分别大于35%和45%;黑色区是富Fe-Ti-Si合金相,钛和铁分别大于20%和30%;其余区域为富Fe-Si合金相,Al、Ti含量较少,Ti含量高颜色深,Al含量多颜色浅,其它金属杂质元素则无规律地分布于杂质相中。杂质分布规律与其含量和分配系数相一致。     

冶金级硅氧化精炼提纯制备太阳能级硅研究进展

综述了目前冶金级硅氧化精炼制备太阳能级硅的研究进展,详细介绍了熔渣精炼、吹气氧化精炼和热等离子体精炼的方法和装置以及杂质的去除效果。研究发现:上述氧化精炼方法对硅中杂质元素Al、Ca、Cu、B、P等具有很好的去除效果;熔渣和吹气氧化精炼对Fe不明显,须借助于定向凝固方法才能彻底的去除;吹气氧化精炼和等离子体精炼对硅中B的去除效果十分明显,可使其降低至0.1ppmw以下,这为当前冶金法提纯制备太阳能级硅在技术和工艺上提供了很好的思路;通过氧化精炼,硅中杂质元素完全可以达到太阳能级硅的要求。本文提出,吹气氧化精炼(或等离子体精炼)与定向凝固精炼联合使用并形成规模化和连续化精炼装置是加快我国太阳能级硅产业化进程最切实可行的办法和措施。     

In-line catalytic purification of carbon dioxide used in analytical-scale supercritical fluid extraction

Supercritical fluid extraction analyses are often compromised by trace impurities present in the solvent carbon dioxide. These impurities, commonly used as lubricants in the specialty gas industry, can produce significant background levels, increasing limits of detection and quantification. This problem is especially severe when electron capture detection (ECD) is used for trace concentrations of analytes (e.g., polychlorinated biphenyls and chlorinated pesticides). In this study, an in-line catalyst-based purification system was successfully employed to remove ECD-responsive contaminants from CO2. Low-purity (98%) "Bone Dry" CO2 was purified to levels cleaner than a very-high-purity grade of CO2 specified at less than 10 ppt ECD-responsive contaminants. Purification was successfully applied to extremely sensitive on-column experiments as well as higher flow rate off-line experiments. In addition to lowering limits of detection and quantification, significant cost savings can be realized by purifying inexpensive, low-purity CO2 instead of relying on much more expensive, prepurified CO2.