High-Temperature Refining of Metallurgical-Grade Silicon: A Review

Among currently known alternatives for renewable energy sources, solar power is generally regarded as having the most potential to satisfy the ever-growing demand. While solar photovoltaic power is a well-established technology, its widespread uptake has been hindered by the prohibitively high price of units and thus electricity. This is due mainly to the high cost of the silicon used to fabricate the devices. This article presents a review of the development of established pyrometallurgical techniques as applied to refining metallurgical silicon to solar grade for the purposes of reducing reliance on expensive traditional silicon feedstock. Four basic high-temperature methods??solvent refining, vaporization, electrorefining, and slag treatment??are described, and the limitations and advantages of each method are presented. It is apparent that these techniques are very useful for removing impurities from silicon, but are often selective and not able to remove all problematic elements. Therefore, refining may need to be as a sequence of steps, targeting specific elements each time, or as novel methods combining multiple techniques simultaneously. Ultimately, the successful approach will have to achieve large-scale production by cost-effective means to replace current methods.     

A New Method for Estimation of Emissions and Sources of Measurements Error in the Silicon Refining Process

In the production of metallurgical grade silicon (MG-Si), fugitive emissions are a serious concern due to the health risks associated with the fumes formed in different parts of the production. The fumes are also a potential environmental hazard. Yet, the chemical composition of the fumes from most process steps in the silicon plant, such as oxidative refining ladle, remains unknown. This in turn constitutes a problem with respect to the correct assessment of the environmental impact and working conditions. A comprehensive industrial measurement campaign was performed at the Elkem Salten MG-Si production plant in Norway. Samples of the ingoing and outgoing mass flows were analyzed by high-resolution inductively coupled plasma mass spectrometry, with respect to 62 elements. In every step of the sampling and sample treatment processes, possible sources of error have been identified and quantified, including process variation, mass measurement accuracy, and contamination risk. Total measurement errors for all elements in all phases are established. The method is applied to estimate the order of magnitude of the elemental emissions via the fumes from the tapping and refining processes, with respect to production mass and year. The elements with higher concentrations in the fume than slag and refined silicon include Ag, Bi, Cd, Cu, In, K, Mg, Na, Pb, Rb, Se, Sn, Tl, and Zn: all being present in the ppm range. This work constitutes new and vital information to enable the correct assessment of the environmental impact and working conditions at an MG-Si plant.     

Element Distribution in Silicon Refining: Thermodynamic Model and Industrial Measurements

To establish an overview of impurity elemental distribution among silicon, slag, and gas/fume in the refining process of metallurgical grade silicon (MG-Si), an industrial measurement campaign was performed at the Elkem Salten MG-Si plant in Norway. Samples of in- and outgoing mass streams, i.e., tapped Si, flux and cooling materials, refined Si, slag, and fume, were analyzed by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), with respect to 62 elements. The elemental distributions were calculated and the experimental data compared with equilibrium estimations based on commercial and proprietary, published databases and carried out using the ChemSheet software. The results are discussed in terms of boiling temperatures, vapor pressures, redox potentials, and activities of the elements. These model calculations indicate a need for expanded databases with more and reliable thermodynamic data for trace elements in general and fume constituents in particular.     

Novel Method for Refining Coarse Eutectic Carbides in Ultrahigh-Carbon Steel

Metal Science and Heat Treatment - The structure and mechanical properties of an ultrahigh-carbon steel modified with amorphous ferrosilicon with a low melting point are studied. The methods of...     

100 t LF精炼脱硫生产实践

对影响钢水脱硫的热力学因素和动力学因素进行了分析讨论,并结合武钢一炼钢的实际和品种特点,从转炉冶炼控制,LF快速化渣、造渣,精炼温度,底吹氩流量,钢渣脱氧,合理选择精炼渣系以及优化炉渣成分等方面提出了LF精炼脱硫的技术措施。     

添加含碳熔剂细化镁合金晶粒的方法

提出了镁合金用粉末状晶粒细化剂加入的新方式-子母球混合粉压块加入法，以常用镁合金AZ31为基，将采用普通方式加入细化剂和采用子母球混合粉压块加入细化剂的镁合金微观组织进行了定量比较，并对熔炼时碳粉在熔体中的分散方式进行了简单的模拟，最后采用纯镁对该加入方式的有效性进行了进一步的验证，试验证明，该加入方式对以改善碳粉对镁及其合金的细化效果，并且操作简单易行。     

ZLSi7Cu2Mg在熔剂中的精炼方法研究

介绍了熔剂精炼ZLSi7Cu2Mg的实验装置以及实验过程。选用5种无机盐混合,对ZLSi7Cu2Mg铝合金进行了精炼实验,通过实验总结出电极熔化速度与电流的变化关系;对比分析了精炼与未精炼试样抗拉强度、伸长率及其金相组织。结果表明:在能够熔化电极的前提下,电流越小,精炼后的铝合金性能越好;熔剂45%KCl+45%MgCl2+10%Na3AlF6对铝熔体的精炼效果最好;精炼后铸件的力学性能相对未精炼时有一定程度的提高。     

硅片电火花线切割加工技术的发展

利用电火花线切割加工技术加工硅片能直接得到大尺寸、超薄硅片,且不受硅晶体晶向的影响,设备成本低,切割效率较高,因而研究和开发硅片电火花线切割加工技术是一个很有发展潜力和应用前景的课题。     

Silicon nanoelectronics and beyond: An overview and recent developments

This year marks the 40th anniversary of the invention of the first beam-lead device by Lepselter et al. Lepselter and coworkers proposed a method of fabricating a new semiconductor device structure and its application to high-frequency silicon switching transistors and ultra-high-speed integrated circuits. Beam-lead technology, also known as air-bridge technology, has established itself for its unsurpassed reliability in high-frequency silicon switching transistors and ultra-high-speed integrated circuits for telecommunications and missile systems. The beam-lead device became the first example of a commercial microelectromechanical structure (MEMS). Since its inception, MEMS has taken advantage of the evolving silicon technology, resulting in today’s nano-electromechanical structure and nano-optomechanical structure. In this paper, an overview of recent developments of silicon nanoelectronics is presented. For more information, contact N.M. Ravindra, New Jersey Institute of Technology, Interdisciplinary Program in Materials Science and Engineering, Department of Physics, Newark, New Jersey 07102; (973) 596-3278; fax (973) 642-4978; e-mail nmravindra@comcast.net.     

反应磁控溅射法制备二氧化硅薄膜的研究

采用反应磁控溅射的方法沉积二氧化硅薄膜,研究了二氧化硅薄膜的光学特性,并与用反应离子束溅射方法沉积二氧化硅薄膜进行了对比。实验结果表明:用反应磁控溅射法沉积二氧化硅薄膜,薄膜的折射率、沉积速率主要受反应气体(氧气)浓度的影响,氧气含量超过15%(体积分数)后,溅射过程进入反应模式,沉积速率随氧气浓度增加而降低;入射光波长为630 nm时,薄膜折射率为1.50。对比2种薄膜沉积方法后确定,在二氧化硅薄膜工业生产中,反应磁控溅射方法更为可取。     

ZHPb59-1铅黄铜精炼等级的快速判定方法及其原理

CuAlB精炼剂在ZHPb59-1铅黄铜熔炼过程中经常使用,一般以B的加入量为(8～12)×10-4%为宜.另外,ZHPb59-1铅黄铜对Sn、Fe、Ni等杂质元素量也有严格的限定,因为杂质元素如同B一样,不同含量对精炼效果有不同影响.     

硅钢片硬质合金复合冲模工作零件加工方法

介绍了硅钢片硬质合金复合冲模与凸模、凹模、凸凹模等的制造方法。     

Better Living Through Chemistry: Evolving GasNets for Robot Control

This paper introduces a new type of artificial neural network (GasNets) and shows that it is possible to use evolutionary computing techniques to find robot controllers based on them. The controllers are built from networks inspired by the modulatory eff ects of freely diff using gases, especially nitric oxide, in real neuronal networks. Evolutionary robotics techniques were used to develop control networks and visual morphologies to enable a robot to achieve a target discrimination task under very noisy lighting conditions. A series of evolutionary runs with and without the gas modulation active demonstrated that networks incorporating modulation by diff using gases evolved to produce successful controllers considerably faster than networks without this mechanism. GasNets also consistently achieved evolutionary success in far fewer evaluations than were needed when using more conventional connectionist style networks.     

二异戊基硫醚萃取分离钯

对原二异戊基硫醚萃取分离钯工艺进行了改进，如萃金余液性质调整，萃取剂预先除味，改变有机相、反萃剂及洗液组成以及洗水、再生液、平衡液循环使用等。试验证明，改进后的工艺明显优于二正辛基硫醚和二正己基硫醚萃取钯。     

一种自动化单元批量生产质量分析新方法

以机械制造企业自动化单元的生产过程质量控制为研究对象,提出了一种自动化单元批量生产质量分析的新方法,对生产过程的中零件质量建立状态空间模型,提取质量特征矢量来描述某一阶段的加工状态。以质量状态变换方程刻画零件的加工过程,通过状态变换方程的串联叠加实现对多工序生产系统的数学描述;通过数控生产线监控管理系统获取生产过程中零件质量相关信息,以这些数据为基础条件求解生产系统特征矩阵,并结合生产过程特征熵来评价生产过程,实现质量控制。实例分析说明该方法正确性和有效性,为自动化单元批量生产提供一种有效的生产过程评价和产品质量分析方法。