低温净化冶金硅工艺(英文)

硼、磷杂质的去除在冶金净化法生产太阳能级多晶硅工艺中耗能最大。金属熔析净化法可以实现冶金硅在金属液中低温下熔化,而后再结晶净化,是一种可行的低能耗硼磷去除方法。对熔析体系的选择原则进行总结,筛选出铝、锡和铟金属作为合适的熔析介质。对于Sn-Si体系,1500K时硼的分凝系数为0.038,远小于纯硅熔点的对应值0.8。冶金硅二次熔析净化处理可使硼的质量分数由15×10-6降至0.1×10-6,而多数金属杂质可一次性去除至0.1×10-6以下。在熔析过程中,杂质和硅生成化合物是主要的杂质去除方式。提出一种以金属熔析法为基础的低温冶金硅净化工艺。     

太阳能晶体硅切割废料中高纯硅的提取(英文)

研究从太阳能晶体硅切割废料中制取高纯硅。分析切割废料的组成、粒度分布等,利用物理沉降法对废料中的硅粉进行富集,然后经酸洗除杂。研究酸洗工艺参数如酸洗时间、温度、固液比等对提纯效率的影响,并优化工艺参数。最后将酸洗除杂的硅富集料进行真空高温熔炼获得含99.96%Si、1.1×10-6B及4.0×10-6P(质量分数)的高纯硅。结果表明:从晶体硅切割废料中回收太阳能多晶硅是未来的一个重要发展方向。     

Boron removal from metallurgical grade silicon by oxidizing refining

A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species BxOy and BxHzOy in O2 and H2O-O2 atmosphere respectively. The equilibrium pressure of BxHzOy is 105-1010 times that of BxOy. Boron is removed and its content in silicon is reduced from 18×10-6 to 2×10-6 in the Ar-H2O-O2 atmosphere in the electric arc furnace.     

利用废渣冶炼回收硅铁的研究

利用金川公司的废渣和石英砂为主要原料,以焦碳和木炭作为还原剂,利用自制的小型直流电弧炉和混合加料法冶炼硅铁合金,并利用XRD和光学显微镜对合金进行了分析。实验表明,当石英砂质量分数为20%,炉料的配碳量为1.9∶1时,硅铁的回收率最高,产物中得到了Fe5Si3和Fe3Si。利用直流电弧炉冶炼硅铁合金具有独特的优势,在冶炼过程中解决了炉底上涨的技术难题。本研究不但可以解决废渣利用方面的问题,而且能合理的利用废渣起到环保作用,还能产生更好的经济效益。     

An Evolving Method for Solar-Grade Silicon Production: Solvent Refining

Use of photovoltaic (PV) power generation has recently been increasing rapidly because it provides clean, renewable energy. While production of solar-grade silicon (SOG-Si) has been dominated recently by the modified Siemens process and a fluidized bed reactor process, obtaining a stable supply of SOG-Si at lower cost is essential to further increases in PV installation. Metallurgical production offers benefits in productivity and possibly also in process cost. Several metallurgical processes, such as directional solidification, vacuum melting, and plasma melting, have been developed, but significant cost reductions or dramatic improvements in productivity are required to enable metallurgical refining to become the major route for SOG-Si production. The solvent refining process offers the possibility of cost reduction due to its high purification efficiency and low processing temperature. This paper reviews solvent refining processes for SOG-Si purification, emphasizing their advantages and identifying the problems that must be solved for process development.     

A study on reactive braze coating of （TiC＋Cr3C2 ）／Fe composite coatings

0Introduction Inmanycases,itisrequiredthatsurfacesofstructur alcomponentshavegoodpropertiessuchasthewear,cor rosionandoxidationresistancessoastotaketheadvantage ofalongerservicelifeandtheconsequentreductionofto talcost.Tothisend,numeroussurfaceprocesse…     

中频炉和VOD双联法冶炼不锈钢工艺

介绍了中频炉熔炼及VOD精炼X3CrNiMoN27-5-2不锈钢的生产工艺及措施.采用优质原材料,调整化学成分及出炉温度,控制VOD精炼炉吹氧真空度、吹氧强度、吹氧时间、氩气流最等工艺参数,并结合氧势图和废气温度,准确判断吹氧终点时间和极限真空保压时间,其冶金效果可以达到铸件材质的质量标准.     

氩弧熔覆Cr—Si—B系合金组织与性能

研究了氩弧熔覆层的组织与性能,通过对激光溶覆、火焰熔覆的组织化学对比分析,说明了白亮层盛开过程及产生条件。指出氩弧覆能实现熔覆层的冶金结合且具有良好的成形性,使用灵活,能得到与激光熔覆相近性能的熔覆层,可以在生产中采用氩弧熔覆工艺。     

钛合金表面氩弧熔覆原位合成TiB2-TiN涂层组织及耐磨性能

以BN和Ni60A合金粉末为熔覆材料,采用氩弧熔覆技术在TCA合金表面原位合成TiB2-TiN增强颗粒耐磨涂层．利用x射线衍射仪、扫描电子显微镜和摩擦磨损试验机对熔覆层的组织和性能进行分析测试．结果表明,复合涂层的显微组织沿层深方向分为熔覆区、结合区和热影响区;熔覆层与基体呈良好冶金结合,TiB2-TiN颗粒弥散分布,...     

Hydrometallurgically recovering zinc from electric arc furnace dusts

The increasing use of zinc-containing scrap for steel production has lead to a high zinc content in the electric arc furnace and converter flue dusts. The cost of disposing of this residue is high due to environmental restrictions. Various recycling processes have been developed for these dusts, but most never reached the pilot plant stage and many investigations were stopped because of metallurgical and economical inefficiencies. While pyrometallurgical methods have to deal with high energy consumption, low zinc yield, and valueless residues, hydrometallurgical processes could offer an economical recycling alternative. This paper describes hydrometallurgical methods for recovering zinc from steel industry dust. These methods can be integrated in the primary zinc-winning process or in galvanization. Investigations of sulfuric-acid leaching show high zinc solubility but also a high iron content in the final liquor. As a result, steps for purification are required that cannot be conducted economically. Alternatively, a NaOH leaching gives a satisfying zinc yield and a very low solubility for the iron that remains in the residue. For more information, contact J. Antrekowitsch, University of Leoben, Nonferrous Metallurgy Department, Franz-Josef-Str. 18, Leoben, Styria A-8700, Austria; +43-3842-402322; fax +43-3842-402627; e-mail antreko@unileoben.ac.at.     

中频感应电炉熔炼铸态铁素体球墨铸铁工艺

阐述了中频感应电炉熔炼铸态铁素体球铁的生产工艺,通过对原材料的选择和化学成分的控制,可以生产铸态铁素体球墨铸铁,可获得较好的球化级别,而且生产工艺稳定、可靠,质量高、成本低,力学性能达到和超过国家标准。     

Vacuum distillation refining of metallurgical grade silicon （Ⅰ） ——-Thermodynamics on removal of phosphorus from metallurgical grade silicon

The removal of impurity phosphorus from metallurgical grade silicon is one of the major problems on purification of metallurgical grade silicon for solar grade silicon preparation. The thermodynamics on vacuum refining process of the metallurgical grade silicon was studied via separation coefficient of impurity phosphorus in the metallurgical grade silicon and vapor-liquid equilibrium composition diagram of Si-P binary alloy at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined. The results show that the vacuum distillation should be taken to obtain silicon with less than 10^-7 P, and the impurity phosphorus is volatilized easily by vacuum distillation in thermodynamics. Phosphorus is distilled from the molten silicon and concentrated in vapor phase.     

QT350-22同步带轮铸件的生产工艺

介绍了同步带轮B264-14M55(4040)的铸件结构,详细阐述了其生产工艺:采用呋喃树脂自硬砂造型,封闭式浇注系统,浇口比为∑F内:∑F横:∑F直=1:1.25:1.36,轮缘处设置3个明顶冒口,轮缘外部放置5块随形外冷铁,轮毂底部设置外冷铁;选用低Si、低Mn、低S、低P的生铁,废钢选用45钢板及圆钢的下脚料,回炉料选用该牌号的浇、冒口及废铸件,利用1.5 t中频感应电炉熔炼,采用堤坝式球化包进行球化处理,出炉温度控制在1 480~1 500℃,选用铁素体专用球化剂和Ba-Si-Fe孕育剂,并采取两次孕育的方法;采用高温石墨化2段退火工艺。最终生产铸件的球化等级为2级,石墨大小为6级,铁素体体积分数高于95%,力学性能符合技术要求。     

Preparation and Optimization of Vanadium Titanomagnetite Carbon Composite Hot Briquette: A New Type of Blast Furnace Burden

A new type of blast furnace burden, named VTM-CCB (vanadium titanomagnetite carbon composite hot briquette), is proposed and optimized in this paper. The preparation process of VTM-CCB includes two components, hot briquetting and heat treatment. The hot-briquetting and heat-treatment parameters are systematically optimized based on the Taguchi method and single-factor experiment. The optimized preparation parameters of VTM-CCB include a hot-briquetting temperature of 300°C, a coal particle size of <0.075 mm, a vanadium titanomagnetite particle size of <0.075 mm, a coal-added ratio of 28.52%, a heat-treatment temperature of 500°C and a heat-treatment time of 3 h. The compressive strength of VTM-CCB, based on the optimized parameters, reaches 2450 N, which meets the requirement of blast furnace ironmaking. These integrated parameters provide a theoretical basis for the production and application of a blast furnace smelting VTM-CCB.     

Cobalt pressure leaching and reduction at garfield

Cobalt recovery from arsenical concentrates by pressure leaching and reduction involves special methods and operating problems. Principal steps in the process are auto-oxidation acid leaching under pressure, filtration of the tailings, purification of the solution, hydrogen reduction of the ammoniacal solution, and melting in an electric arc furnace to remove sulfur and granulate the metal.     

Impurity removal and overall rate constant during low pressure treatment of liquid silicon

The research presented analyzes the effect of low pressure on the amount and reduction of impurity elements in upgraded metallurgical grade silicon. The achieved pressure was 5 kPa in the commercial electro-resistance furnace in the magnesia and mullite refractory material. The chemical composition was determined by ICP-MS method. Elements such as Al, Fe, Mn, Cu or Zn had the highest evaporation rates where higher evaporation was achieved at higher melt temperatures. The overall rate constant was deduced for four melt temperatures indicating high values even for low melt temperatures. The interfacial boundary between Si and mullite refractory showed no dissolution of Al into the liquid Si.     

Metal Recovery from Scrap and Waste

The depletion of high grade ores and accumulation of huge quantities of metallic scrap and metallurgical wastes have generated significant interest in their processing. In this paper, both pyrometallurgical, as well as hydrometal-lurgical, methods for metal recovery from scrap and wastes (viz., slag, dusts, aqueous effluents, sludge and residues) are reviewed. Scrap recycling and the processing of metallurgical wastes will pollute the environment to a lesser extent and consume less energy compared to the primary metal production. Reprocessing metallurgical waste (viz., slag, red mud, etc.) serves a social objective and ensures raw materials conservation. Research trends reveal that hydrometallurgy may play a dominant role in the waste treatment. Recently developed processes like continuous ion exchange and fluidized bed electrolysis may be used in the future for recovering metals from dilute solutions.     

Purification of metallurgical silicon using iron as impurity getter,part II: Extent of silicon purification

Purification of metallurgical grade silicon (MG-Si), using iron as the impurity getter has been investigated. The technique involves growing Si dendrites from an alloy of MG-Si with iron, followed by their separation using a gravity based technique and acid leaching. The effects of cooling rate of the alloy and the subsequent quenching temperature on the segregation of the impurities were studied. It was found that slow cooling of the alloy below the eutectic temperature causes an increase in the Si impurity concentration due to diffusion of the impurities from the alloy to the Si. Quenching the alloy from temperatures above the eutectic eliminated this effect, increasing the purity of the Si product. A significant reduction in the concentration of the major impurities was achieved, making the Si product a suitable feedstock for solar grade silicon generation. The concentrations, in ppmw, of some elements in the Si product are Al: 10, B: 2, Mn: 3, Ni: 3, Cr: 1, Fe: 1, P: 29. Other impurities including V, Ba, Li, Be, and Mg were all below 0.5 ppmw.     

Microstructure and formation mechanism of in-situ TiC-TiB2/Fe composite coating

Steel matrix composite coatings locally reinforced with in situ TiC-TiB2 particulates were prepared by argon arc cladding（AAC） with different mass fractions of Fe and Ti＋B4C powders as the binding materials. The microstructure, micro-hardness and wear resistance were investigated using SEM, XRD, Micro-hardness Tester, and Friction and Wear Tester, respectively. The results show that the main phases of coating are TiC, TiB2 and a-Fe. The excellent metallurgical bonding is formed between the composite coating and substrate. The coating is uniform, continuous and almost defect-free and the particles are dispersively distributed in the cladded coating. Moreover, the formation mechanism was investigated. With the increase of the content of TiC＋TiB2, the micro-hardness and wear resistance are also improved at the room temperature under normal atmosphere conditions.     

铝硅熔体超重力凝固提纯硅(英文)

研究超重力场下铝硅过共晶熔体凝固精炼提纯冶金硅。实验结果表明:超重力作为一种强化分离手段,可以实现铝硅合金中初晶硅颗粒的富集分离。在超重力作用下,铝硅合金中精炼硅颗粒沿超重力方向富集在铝硅合金下部。用王水溶解其中的铝,得到初晶硅颗粒。通过分析初晶硅中杂质含量可知,与冶金硅原样相比,精炼后的硅纯度由99.59%提高到99.92%,硼和磷的质量分数分别由8.33×10-6和33.65×10-6降低到5.25×10-6和13.50×10-6,表明该提纯方法可行。