CaO-SiO_2熔渣精炼去除冶金级硅中杂质硼(英文)

利用CaO-SiO2熔渣去除冶金级硅(MG-Si)中的杂质硼。热力学分析和实验结果表明:纯SiO2基本上不能去除冶金级硅中的杂质硼。通过建立硼的分配系数与熔渣中SiO2和CaO活度之间的关系,从热力学上对CaO-SiO2熔渣的除硼能力进行表征。结果表明:随着渣中CaO配比的升高,硼的分配系数和去除效率大大提高。当熔渣组成为60%CaO-40%SiO2(质量分数)时,硼的分配系数达到最大值1.57。当渣硅比为2.5,精炼温度为1600°C以及精炼时间为3 h时,利用60%CaO-40%SiO2熔渣可以将冶金级硅中的硼含量从18×10-6降低至1.8×10-6,去除效率达到90%。     

Removal of Boron in Silicon by H2-H2O Gas Mixtures

The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52?ppm initially to 0.7?ppm and 3.4?ppm at 1450°C and 1500°C, respectively, after blowing a H₂-3.2%H₂O gas mixture for 180?min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.     

冶金级硅吹Ar-H2O混合气精炼除

通过吹高纯氩气和水蒸汽混合气体的方法除去冶金级硅中的杂质磷。采用自行设计的吹气精炼装置,研究喷嘴类型、精炼时间、精炼温度、精炼气温度、精炼气流速等因素对除磷效果的影响。研究表明：使用侧壁和底部多孔型喷嘴,精炼时间3 h,精炼温度1793 K,精炼气温度373 K,精炼气流速2 L/min作为最优吹气精炼条件时,冶金级硅熔体中的磷元素质量分数由94×10-6降低到11×10-6。表明吹气精炼是一种有效的去除冶金级硅中磷的方法。     

电弧炉动态无功补偿装置的研制及应用

铸钢行业重要生产设备的电弧炉是一种高耗能的熔炼设备,作者基于TCR+FC型SVC动态无功补偿及滤波装置,设计制造了HMV-FCS-450-10/235型电弧炉动态无功补偿装置以提高电效,降低电弧炉能耗.同时,改善了电网电能的质量,取得了显著的节能降耗效果.     

铁捕集富集料中铂族金属的深度富集技术

铁捕集法从二次资源中回收铂族金属的工艺已经得到了工业化应用,捕集过程在电炉或等离子炉中进行。等离子炉熔炼富集物硅含量高,导致其结构致密、惰性、耐腐蚀,需要先除硅才能获得高的溶解率,除硅技术主要有碱融溶-浸出法、氧化分离法等;电炉熔炼富集物硬度极高、难以破碎,工艺上采用高压雾化-酸溶、碎化-酸溶、电解等工艺进行深度富集。本文综述了含铂族金属铁合金深度富集技术的研究现状,并对主要技术存在的优缺点进行了评述。随着各行业对铂族金属需求量的增加,对铂族金属回收率的要求将越来越高,因此,还需进一步完善铂族金属回收技术,提高铂族金属回收率。     

船用曲臂锻件用54t下注钢锭的试制

介绍了上海重型机器厂有限公司船用曲臂锻件用54 t下注钢锭的试制情况。电弧炉冶炼时配船用割板边角料、一类生铁。LF钢包精炼炉钢水采用铝锭预脱氧,经过精炼及VD处理后,钢水中的内生夹杂物少而且小,无长条状或纺锤状的MnS夹杂。精炼渣量控制在16 kg/t钢～20 kg/t钢,精炼钢水入真空前全部进入熔炼规范。VD有效真空度≤65 Pa,有效真空处理时间45 min～50 min。真空后定[H]为1.0×10-6、(O)为6.2×10-6。氩气保护大气下注,流钢砖材质为莫莱石,54 t下注钢锭锭身浇铸时间28 min,冒口补缩时间14 min。WHF法四火锻压,采用一次锻后正火及扩氢回火的热处理工艺。     

电弧炉炼钢除尘系统

主要论述了电弧炉的烟尘产生以及除尘办法。提出利用侧吸罩、顶吸罩和活动罩相结合的方式对电弧炉冶炼进行除尘处理，不但能够收集电弧炉各个熔炼时期的烟气，而且还能够有效降低烟气温度，直接进入到布袋除尘器中进行处理，排放浓度远低于国家环保要求。     

CaCl2-NaCl-CaO熔盐中电解精炼Si的研究

以冶金级Si和电解Cu为原料,制备了Cu-31Si（摩尔分数,%）合金.以Cu 31Si合金为阳极、Mo为阴极和参比电极,采用循环伏安和计时电位方法研究了1173 K下熔盐81CaCl₂ 8.0NaCl 8.5CaO-2.5Si（摩尔分数,%）的阴极行为,讨论了熔盐中Si电解精炼过程的还原步骤.用SEM,EDS和电感耦合等离子原子发射光谱仪（ICPAES）分析和表征了Si晶体的形貌和组成.电解精炼后得到了多晶Si,与冶金Si原料相比,主要杂质含量都显著降低,特别是对太阳能级Si危害较大的杂质B和P去除效果明显,分别从42×10^-6和25×10^-6降至4.5×10^-6和8.2×10^-6.电解精炼过程的电流效率为84.4%.     

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。     

Preparation and Arc Melting of High Purity Iron

A method is described for purifying iron in batches of 150 lb or more. Oxygen, carbon, nitrogen, and sulphur are removed from flakes of electrolytic iron by treatment in wet and then dry hydrogen. A special consumable-electrode arc furnace is used to remove hydrogen and to melt the flakes into ingots.     

Oxidation of ultra low carbon and silicon bearing steels

Oxidation tests were carried out in samples from an ultra low carbon and two silicon bearing steels to determine the distribution and morphology of the oxide species present. The ultra low carbon steel was oxidized for short periods of time within a chamber designed to obtain thin oxide layers by controlling the atmosphere, and for longer times in an electric furnace; the silicon steels were reheated only in the electric furnace. The chamber was constructed to study the behaviour encountered during the short period of time between descaling and rolling in modern continuous mills. It was found that the oxide layers formed on the samples reheated in the electric furnace were made of different oxide species. The specimens treated in the chamber had layers made almost exclusively of wustite. Selected oxide samples were studied by scanning electron microscopy to obtain electron backscattered diffraction patterns, which were used to identify the oxide species in the layer.     

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。     

硼膜多步骤注N的镀层结构研究

用离子束溅射硼靶，在W6o5Cr4V2钢上宙积一层硼膜，再用反冲注入法注氮以形成氮化硼（BN），注入时采用逐次递减能量（即50kV,30keV,10keV0的多步骤注入。用XPS分析膜的成分深度分布及元素的化学价态；用傅立叶红外（FTIR）反射谱分析膜的结构，结果表明：膜基界面产生混合，与用单一能量注入相比，多步骤注入时，膜层的N／B分布比较均匀；硼在膜中以BN形式存在，膜深度较大处为a-BN或h-BN，并且随着深度的降低，膜有向c-BN转化的趋势。     

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.     

ZnO-Al2O3-B2O3-SiO2系微晶玻璃结晶行为及对金刚石磨料的润湿性

为改良微晶玻璃结合剂,以熔融法制备锌铝硼硅系微晶玻璃,研究硼硅比和烧结工艺对其热学、力学性能,析晶行为,显微结构及对磨料的润湿性的影响。发现:硼含量增多,锌铝硼硅系玻璃的热膨胀系数升高、耐热性下降、抗弯强度先升高后降低;硼含量过高时,结合剂完全包覆磨料,不利于磨削加工。另一方面,硅含量增多,玻璃的黏度增大、对磨料的润湿性能变差;硅含量过高时,试样抗弯强度不足。ZABS系微晶玻璃的最佳配比w_B:w_Si=1:1。热处理工艺为710℃时保温2 h,得到的试样的热膨胀系数为5.132 7×10-6℃-1,抗弯强度达78 MPa,对磨料的润湿性好。      

Reaction between Ti and boron nitride based investment shell molds used for casting titanium alloys

The aim of this paper was to study the reaction between a Ti-6Al-4V alloy and boron nitride based investment shell molds used for invest- ment casting titanium. In BN based investment shell molds, the face coatings are made of pretreated hexagonal boron nitride (hBN) with a few yttria (Y2O3) and colloidal yttria as binder. The Ti-6Al-4V alloy was melted in a controlled atmosphere induction furnace with a segment water-cooled copper crucible. The cross-section of reaction interface between Ti alloys and shell mold was investigated by electron probe micro-analyzer (EPMA) and microhardness tester. The results show that the reaction is not serious, the thickness of the reacting layer is about 30-50 μm, and the thickness of α-case is about 180-200 μm. Moreover the α-case formation mechanism was also discussed.     

Mechanism of boron removal from Si–Al melt by Ar–H2 gas mixtures

A new method about purification of metallurgical grade silicon (MG-Si) by a combination of Si–Al solvent refining and gas blowing treatment was proposed. The morphologies and transformation of impurity phases, especially for boron and iron in Si–Al melt were investigated during Ar–H₂ gas blowing treatment. The mechanism of boron removal was discussed. The results indicate that gas blowing can refine grain size and increase nucleation of the primary Si. Boron can be effectively removed from MG-Si using the Ar–H₂ gas blowing technique during the Si–Al solvent refining. Compared with the sample without gas blowing, the removal efficiency of boron increases from 45.83% to 74.73% after 2.5 h gas blowing. The main impurity phases containing boron are in the form of TiB₂, AlB₂ and VB compounds and iron-containing one is in the form of β-Al₅FeSi intermetallic compound. Part of boron combines [H] to transform into gas B_xH_y (BH, BH₂) and diffuses towards the surface of the melt and is volatilized by Ar–H₂ gas blowing treatment under electromagnetic stirring.     

Removing impurities from steel scrap using air and chlorine mixtures

The presence of zinc in steel scrap causes difficulties in the production of steel and leads to environmental problems. This article describes a separation route using air and chlorine mixtures to remove zinc from steel scrap prior to melting in an electric arc furnace. Thermodynamics shows that zinc chloride is more stable than its oxide, while the reverse is true for iron. Through the use of an air and chlorine mixture (10:1), zinc is selectively removed from steel at 800°C in the laboratory. The reaction products characterized by various analytical techniques confirm the thermodynamic analysis. This process offers an attractive solution to obtain clean steel scrap and useful chemicals. Editor’s Note: A hypertext-enhanced version of this article appears on the JOM web site at www.tms.org/pubs/journals/JOM/9908/Tee-9908.html. For more information, contact J.K.S. Tee, University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, United Kingdom; telephone 44 (0)1223 334360; fax 44 (0)1223 334567; e-mail ksjt2@hermes.cam.ac.uk.     

A286合金的高温持久性能

为了探究A286合金的高温持久性能,对采用进口电炉+炉外精炼+真空自耗(EAF+LF+VAR)冶炼工艺制备的A286合金进行不同温度和应力的高温持久试验,利用Larson-Miller参数(LMP)预测了A286合金的持久寿命,并分析了断口微观组织演变。结果表明,A286合金应力与LMP之间的关系为σ=-107.30×LMP+3011.02。随着试验温度的降低,A286合金的断裂方式由韧窝和孔洞组成的韧性断裂转为沿晶断裂的脆性断裂。在低温高应力下,裂纹主要在MC和M₂₃C₆处产生,在高温低应力下,裂纹主要在片层状η相处产生。在试验温度650℃、应力450 MPa下,强化机制主要为位错切过γ′相的沉淀强化,在试验温度750℃、应力150 MPa下,强化机制为位错切过γ′相的沉淀强化和位错绕过γ′相的弥散强化,并且晶内析出的TiP₂、(Ti, Nb)C、TiC和NbC等纳米颗粒有利于高温持久蠕变。     

再析直流-空心电极电炉熔炼钛渣的特性

以对照原有钛渣工艺为切入点，从直流一空心电极电炉熔炼所产生的熔池流动特性可以抑制碳热还原过程的碳(氮)化钛生成，和能够气化除杂等几个方面做了简要论述。并着重指出，这些熔炼特性对提高我国钛渣生产技术水平的重要意义。