Electrolytic production of magnesium: Effect of current density

The effect of current density on current efficiency for the electrolytic production of magnesium metal and on the wetting of a steel cathode by magnesium has been studied in a proprietary sodium chloride-rich NaCl–MgCl₂ melt at 710±10°C. With the exception of the smallest applied current density, current reversal chronopotentiograms at a small steel electrode in an argon blanketed melt showed a linear increase of current efficiency with increasing current density up to 0.7A cm^–2. The current efficiency then remained constant around 94% over a current range of 0.7–1.2 A cm^–2. Further increase in the current density, however, produced a decline in the current efficiency. Interestingly, a linear increase in the current efficiency with current density even up to 1.2 A cm^–2, the highest applied current, was observed in a laboratory cell which simulated the production cell practice. The extent of the steel wetting by molten magnesium decreased with decrease in the cathodic current density, and the wetting was poor below 0.4 A cm^–2. This study suggests that magnesium cells can be run at higher current densities than 0.3–0.5 A cm^–2, the average operating current density in commercial cells, to maximize the current efficiency, the production rate and the space time yield. Other variables in production cells may make higher current density operation difficult in practice.     

Using SS coal in silicon production

The industrial use of Kuznetsk Basin SS coal in silicon production is considered. The influence of SS coal quality on the operation of electrothermal furnaces is studied.     

硅粉生产技术评说

介绍了甲基氯硅烷合成对硅粉的工艺要求,列出了常用的硅粉生产工艺如雷蒙法、对辊法、盘磨法和冲旋法,从硅粉的活性、粒径、单机生产能力、加工成本、使用可靠性和环保状况等方面比较了这几种工艺的特点;讨论了制粉工艺对硅粉的微观结构、活性、粒径及其分布、外观的影响,最后介绍了制粉刀具的特点。     

有机硅离型纸的生产

简述有机硅离型纸的生产与几种离型纸的性能     

四氟化硅生产工艺研究进展

四氟化硅作为生产多晶硅及其衍生物的原料,随着电子工业的发展以及硅基产业的扩大,对于四氟化硅的需求量逐渐增加。对四氟化硅生产工艺的研究越来越引起人们的重视。详细介绍了制备四氟化硅的4种方法,含硅源物质与含氟基团物质合成法、氟硅酸盐热解法、氟硅酸法、硫酸法,综述了国内外制备四氟化硅的研究进展情况,并评述了各工艺的特点。就目前研究表明,四氟化硅制备工艺需向环保、节能、高收率方向发展。     

Electrolytic production of metallic cadmium and cadmium–sodium alloys in alkali melts

Reprocessing of cadmium-containing wastes and used storage batteries produces cadmium oxide. Electrowinning of the metal from an alkali melt is proposed for processing of CdO and production of metallic cadmium or cadmium–sodium alloys. The design of a laboratory electrolyzer is discussed. Technological parameters of the electrolysis process are determined. Applied and engineering aspects of the electrowinning of cadmium and cadmium–sodium alloys are considered. Conditions of the electrolytic production of cadmium are optimized. Specific features of the electrochemical production of cadmium–sodium alloys are analyzed. Electrowinning of cadmium from an acid or chloride solution is considered. The comparison of the electrolysis of aqueous solutions and alkali melts is in favor of the latter.     

多晶硅生产过程分析整体方案

从工艺控制、腐蚀防护、安全监控、环保监测等方面阐述了多晶硅生产过程分析的必要性;并提出了过程分析的整体方案。     

污水深度处理出水回用于多晶硅生产用水

为解决企业生产、生活用水严重短缺的问题,合理利用水资源,企业投资2 000多万元新建1套污水深度处理装置,将经城市污水厂处理后达标排放的污水、企业排放的脱盐水站浓水和循环水站排污水等经该深度处理装置处理后,出水可回用作生产用水。该项技术改造不但保障了多晶硅生产系统的正常运行,而且还大大降低了生产运行成本,取得了很好的经济效益和社会效益。     

SPC技术在高纯四氟化硅生产中的应用

本文以高纯SiF4生产过程中精馏后的HF含量作为质量管理的对象,论述SPC技术在SiF4生产质量控制中的初步应用。     

磷肥副产硅胶生产碳化硅的实验研究

磷肥副产硅胶产量可观,其主要成分是二氧化硅,是加工硅系列产品很好的原料.碳化硅属第三代半导体材料,经济价值高,应用前景好.概述了以二氧化硅为硅源制备碳化硅粉体的主要方法,并介绍利用磷肥副产硅胶碳热还原法生产碳化硅的实验研究.     

电解法制备活性氯的研究

以石墨为阴极和 Ir Ru Ti贵金属氧化物电极为阳极 ,采用离子隔膜电解装置 ,直接电解低浓度的氯化钠溶液制备活性氯。对氯化钠浓度、表观电流密度、温度、p H值、电解时间和流速在电化学反应过程中对活性氯浓度及电流效率的影响进行了研究。由实验结果得出最佳的试验条件为 :电解温度 2 2°C,电解液浓度 2 0 .0 g/ L,电流密度 4.46m A/ cm2 ,时间 2 h,流速 1 .40 m/ s,p H值 4.2 0～ 5.0 0。另外 ,利用活性氯分别对生活污水和河水进行杀菌消毒 ,测定了杀菌消毒后的生活污水和河水中的 COD值、细菌和大肠杆菌。由于活性氯具有很强的杀菌消毒功能 ,此方法在水处理中将会得到广泛应用     

硅粉质量对合成法生产三氯氢硅的影响

分析了硅粉质量对三氯氢硅合成的影响,包括:硅粉粒径对三氯氢硅收率和转化率的影响,硅粉含水量和杂质铝含量对系统运行稳定性的影响,以及杂质含量对合成三氯氢硅产品质量的影响。     

分布式控制系统在四氯化硅生产中的应用

介绍了生产四氯化硅的工艺流程，阐述了SIEMENS公司的分布式控制系统在四氯化硅生产过程中的硬件配置、软件配置和控制系统完成的主要功能。     

多晶硅生产的节能降耗

多晶硅是光伏和半导体产业的重要原材料,介绍了我国多晶硅生产工艺及生产特点,从技术和管理的角度,论述了多晶硅生产节能降耗的必要性、途径和方法,探索集约型的多晶硅生产之路。     

多晶硅生产中硅芯氧化问题探究

改良西门子法生产多晶硅中硅芯是多晶硅生长的载体,硅芯氧化会降低多晶硅产品品质,硅芯氧化的产品对下游铸锭、直拉均有不同程度的影响。目前硅芯氧化是影响多晶硅产品质量的一大问题。分析了硅芯氧化机理,针对相关因素开展了试验,提出了降低硅芯氧化率的措施。     

Kinetic studies on production of silicon carbide from rice husks

Abstract

A kinetic study on a non-conventional route for the production of silicon carbide was carried out on a laboratory scale. Silicon carbide was produced by vacuum pyrolysis of rice husks in the temperature range 1200–1600°C. The resulting products were characterised by XRD and chemical analysis. Attempts were made to develop the parametric relationships correlating the yield of silicon carbide to the process variables and starting material characteristics. Empirical relationships defining the rate of silicon carbide formation as a function of temperature, compaction pressure, CO gas diffusion, and compact porosity are proposed.     

Electrolytic, TEM and Raman studies on the production of carbon nanotubes in molten NaCl

The production of carbon nanotubes (CNTs) by the electrolysis of molten NaCl was investigated by examining the effect of electrolysis duration, current density and voltage. It was found that as the electrolysis was run for longer periods the cathode eroded, changing the current density and consequently preventing nanotube production. The electrolysis was also inhibited by the anode effect and the formation of a sodium layer on the top of the electrolyte. The cell was modified to avoid these difficulties and then optimised under voltage control. Minimum and optimum voltages and current densities were found for CNT production. However, it was discovered that the percentage of nanotube produce still fell as the electrolysis progressed despite minimising the variation in the current density. The nanomaterial produced was studied by TEM. In particular, it was observed that half of the nanotubes were coated with amorphous carbon, suggesting a two-stage growth process. No link, though, was established between the growth conditions and the morphology of the nanotubes. Raman spectroscopy showed that the quality of the nanotubes was comparable to those produced by the CVD route. Titration was used to establish the uptake of sodium into the cathodes, providing evidence for the intercalation growth mechanism.