“2sDR”: Process Development of a Sustainable Way to Recycle Steel Mill Dusts in the 21st Century

Significant amounts of electric arc furnace dust originating from steel production are recycled every year by the Waelz process, despite the fact that this type of process has several disadvantages. One alternative method would be the recovery of very high-quality ZnO as well as iron and even chromium in the two-step dust recycling process, which was invented to treat special waste for the recovery of heavy metal-containing residues. The big advantage of that process is that various types of residues, especially dusts, can be treated in an oxidizing first step for cleaning, with a subsequent reducing step for the metal recovery. After the treatment, three different fractions—dust, slag, and an iron alloy, can be used without any limitations. This study focuses on the development of the process along with some thermodynamic considerations. Moreover, a final overview of mass balances of an experiment performed in a 100-kg top blowing rotary converter with further developments is provided.     

Zinc Recovery via the Flame Reactor Process

A major objective of the zinc industry for the 1990s will be to maintain high zinc recovery while eliminating the disposal of copious quantities of hazardous iron residues. The flame reactor process has demonstrated the potential of meeting this objective by either treating the residues or smelting zinc directly. The process has been proven commercially viable for treating flue dusts generated during electric arc furnace steelmaking. Zinc, lead and cadmium are recovered from the dust as a crude oxide for recycle while a nonhazardous slag is produced for sale. Similar products are efficiently produced from electrolytic zinc plant neutral leach and iron precipitation residues. In addition, the reactor shows promise of fulfilling its original objective of being a low-energy primary zinc smelter by fuming and condensing zinc from roasted concentrates.     

ON THE CONCENTRATION OF CADMIUM AND RECOVERY OF LEAD FROM THE LEAD BLAST FURNACE DUST

本文叙述一个处理铅鼓风炉烟尘的新方法——以碳酸钠为熔剂的铁置换反应法——的试验,并根据铅、镉、砷、锌等在熔炼过程中的转移变化探讨了现有的处理烟尘的石英造渣法的缺点。 主要的试验结果是:富集了烟尘中99.55:的镉于二次烟尘;以粗铅的形式直接回收得95.6:的铅;二次烟尘浸出性能良好,镉的回收率可以达到98.5％。试验证实了这个新方法符合于原料综合利用和一次处理简化操作过程的目的。     

不锈钢电弧炉粉尘直接还原回收工艺研究

电弧炉粉尘巳被列为有害废物，直接还原回收粉尘中有价金属不仅可保护环境，而且可充分利用宝贵的金属资源。采用中频感应电炉模拟电弧炉冶炼工艺进行了A、B、C和D系列实验研究。通过气体成分的检测、钢锭和炉渣的成分分析，了解工艺参数对还原过程的影响，认为电弧炉粉尘直接还原回收工艺切实可行，不影响钢产品质量，为该新工艺的生产实践提供了依据。     

研究大气腐蚀金属表面结露行为的新技术

建立了一种在实验室直接观察金属表面结露过程中简便装置。用半导体制冷器使片状金属样品快速降温,在金属表面上发生结露,同时用金相显微镜观察,还可照相记录。该装置考察了尘埃、盐沾污等因素对于结露行为的影响。     

Über den Mechanismus der Zunderbildung auf Metallen und binären Legierungen

The mechanism of scale formation on metals and binary alloys The scale formed during high-temperature oxidation of many metals consists of two layers which clearly differ from each other morphologically yet occur in the same phase of the reaction product. The inner layer in direct contact with the metal is porous whilst the outer layer is compact. Experiments have shown that the inner layer is formed as a result of secondary processes connected with the influence of the metal consumption zone on the progress of the oxidation process. As the reaction product cannot fully adapt itself to the continually shrinking metal core, a gap occurs between the metal and the reaction product. At the boundary between this gap and the scale, the reaction product begins to decompose. The oxygen atoms liberated as a result of this decomposition react with the metal core, thus giving rise to the formation of the inner layer of scale in the metal consumption zone. The dissociation of the outer layer thus has an anisotrope character so that, in the originally compact layer of scale, a porous consumption zone is formed. The singlephase reaction product is actually composed of three layers, viz. a compact outer layer, a porous transition layer, and a porous inner layer. The porous consumption zone may even comprise the entire originally compact layer of scale so that the oxygen is able to diffuse towards the metal core through fissures and gaps in the reaction product.     

The microwave processing of electric arc furnace dust

An ideal treatment for electric arc furnace (EAF) dust is to cost-effectively process the dust on site to generate high-value products. Microwave heating has the potential to be the ideal approach. In this study, testing was conducted to evaluate the feasibility of treating EAF dust under microwave radiation to produce iron metal and zinc metal instead of zinc oxides as co-products. Microwave processing time and fixed carbon addition amounts were investigated. Different carbons with high fixed carbon contents were also tested and no significant influence was observed. Products of both metallic zinc-rich particles and metallic iron-rich residuals exhibited high purities, which satisfy recycling feedstock requirements.     

Chloride-process treatment of smelter flue dusts

A low-pressure, low-temperature chloride leach process called the Cashman process can be used to extract metals from arsenical flue dusts and residues and fix the arsenic in an environmentally stable form as ferric arsenate (scorodite). The process has been pilot tested in an integrated plant including continuous recycle; during the tests, several tonnes of flue dust were processed. Based on this pilot program, the process was deemed technically feasible, and its products are commercially salable. Residues from this pilot program were also subjected to a long-term stability test.     

黄磷电炉电尘浆提取镓的预处理

根据在电炉还原炼磷过程中,磷灰石中的镓在电尘浆中高度富集,成为可供利用的镓资源,提出了一种提取镓的预处理技术:用浓硫酸熟化电尘,将其中的镓先转化成水溶性化合物,再从预处理物料中浸出镓.考察了预处理过程中电尘的化学和矿物学变化以及影响镓提取率的因素,并给出了适宜的预处理条件;在最佳质量比电尘:水:硫酸=1:1:1,200℃下熟化2 h.实验结果表明,在优化条件下将预处理的电尘在80℃浸出1 h,镓的浸出率可达90%以上.     

The cuprex metal extraction process: Recovering copper from sulfide ores

The Cuprex? metal extraction process produces cathode-grade copper using a hydrometallurgical process based on chloride leaching of sulfide ore concentrates. The process incorporates several novel steps to overcome the major problems associated with earlier chloride-based processes, including mild leaching conditions using ferric chloride as leachant and solvent extraction of copper usinga novel reagent. This produces a highly concentrated cupric chloride electrolyte from which cathode-grade copper is electrowon in the Metclor cell. The technical viability and robustness of the core technology have been proven in a series of large-scale pilot trials. More recent work has concentrated on supplementary processes to convert the copper powder product to an article of commerce and to recover valuable by-products. A fully integrated scheme is now being developed with updated cost estimates.     

锌浸出渣中银的回收方法综述

湿法炼锌是当今世界炼锌主要方法,生产中所得锌浸渣中含有较多的锌及其他有价金属(如银、铅、铜、镉、铟、锗等),作为尾矿堆存不仅会占用大量的土地资源,而且还会造成资源的严重浪费,加之锌浸出渣的长期堆存环境危害性高,因此对锌浸出渣中的有价金属进行综合回收具有十分重要的意义。本文结合国内外锌浸出渣的研究状况,重点针对锌浸出渣中银的回收现状进行论述,全面阐述锌浸出渣中银的工艺矿物学性质、提取工艺流程及发展趋势,对该类资源的综合回收利用具有十分重要的借鉴作用。     

An Approach to Modelling the Forming Process of Sheet Metal-Polymer Composites

Polymer Injection Forming (PIF) and Polymer Injection-Compression Forming (PICF) are new manufacturing technologies for sheet metal-polymer macro-composites, which result from the combination of injection moulding and sheet metal forming. In these processes, a metal blank is formed inside an injection mould by using the pressure of the molten polymer that, after cooling, permanently bonds to the metal sheet creating a fully finished product in only one production step. This paper presents a calibrated multi-physics numerical model of the processes that proves to be suitable to investigate the mutual metal-polymer interactions and to provide a reliable tool in designing the process as well as its control.     

Development of microbially influenced corrosion on carbon steel in a simulated water injection system

Microbially influenced corrosion (MIC) on internal pipeline surfaces has become a severe problem during the water injection process in secondary oil recovery. The formation of a biofilm, normally dominated by sulfate‐reducing bacteria (SRB), is believed to be the critical step of the MIC process. A continuously fed biofilm simulating the water injection process was operated to investigate the influence of biofilm development on MIC behavior in the early phase of corrosion development. The development of the corrosion product film and biofilm was monitored for 5 months with electrochemical impedance spectroscopy, linear polarization resistance, scanning electron microscopy, 3D optical profiling, and direct weight measurement. MIC development was found to comprise three phases: initialization, transition, and stabilization. The initialization phase involved the formation of the corrosion product layer and the initial attachment of the sessile microbes on metal surface. In the transition phase, the MIC process gradually shifted from charge‐transfer‐controlled reaction to diffusion‐controlled reaction. The stabilization phase featured mature and compact biofilm on the metal surface, and the general corrosion rate (CR) decreased due to the diffusional effect, while the pitting CR was enhanced at a lower carbon source level, which supported the mechanism of direct electron uptake from the metal surface by SRB.     

High density powder metallurgy design concepts for powder forging

The forging of powder metal compacted preforms to full density has evolved as an extension of the conventional powder metal process. Indentification and evaluation of the variables in the powder forging process is required to optimize each step of the process, from the powder to the product. Optimization leads to both maximum product quality and minimum process variation.     

回收铝电解炭渣中电解质的研究

研究了回收铝电解炭渣中电解质的焙烧工艺,重点探讨了焙烧温度、停留时间、添加剂加入量对炭渣焙烧工艺的影响,分析了各影响因子与反应率之间的变化关系.在细粒料-回转窑焙烧条件下获得了较高的反应率,回收电解质纯度大干99%,杂质含量低于0.5%,可直接作为铝电解原料.     

Processing to obtain high-purity gallium

Gallium has become increasingly popular as a substrate material for electronic devices. Aside from ore, gallium can be obtained from such industrial sources as the Bayer process caustic liquor that is a byproduct of bauxite processing, flue dust removed from the fume-collection system in plants that produce aluminum by the electrolytic process, zinc refinery residues, gallium scrap materials, and coal fly ash. The purification process for gallium can start with solvent-extraction processes where the concentrations of impurities, especially metals, are reduced to the ppm range. This article describes how ultra-purification techniques can be employed to reduce the undesirable impurities to the low ppb range. The various procedures described give an idea as to the extent of work needed to obtain and prepare high-purity gallium for electronic application. For more information, contact R.G. Bautista, University of Nevada, Department of Metallurgical and Materials Engineering, Reno, Nevada 89557; e-mail bautista@mines.unr.edu.     

锌工业废渣次氧化锌的综合利用

我国冶金工业资源消耗高，二次资源利用率低，有相当大一部分可利用资源变成了污染物，炼锌工业废渣次氧化锌渣就是其中的一种。次氧化锌渣的主要成分是锌、铅、砷、锑、银、铟等元素的化合物。目前，从次氧化锌渣中综合回收铟、锑、砷、锌的工艺尚未成熟，在实际生产中的经济价值得不到体现；但随着近年来金属铟的使用范围不断扩大，需求量增长，导致市场紧俏，价格飚升，人们开始注重次氧化锌这种废渣资源。     

Laboratory observation of dew formation at an early stage of atmospheric corrosion of metals

Dew formation process was conveniently observed using a specially devised experimental arrangement. A semiconductor cooling unit was adopted to chill the plate metal specimen, resulting in moisture condensation onto its surface. Thus dewing process could be observed under metalloscope, and photographs of the dew droplets could be taken when necessary. Initially minute droplets appeared upon the chilly surface. Then adjoining drops merged into a larger one and thus dew drops grew gradually. Finally a thin water film covered the whole surface of the specimen. In this way various influential factors could be evaluated with ease. When the specimen surface was covered with dust, dewing took place surrounding the dust with priority. On the salt polluted surface dewing was much easier. This novel technique may provide an useful tool for study of early stage of atmospheric corrosion.     

Effects of Speeds,Materials, and Tool Rake Angles on Metallic Particle Emission During Orthogonal Cutting

Dry high speed machining has been proposed as a viable and cost-effective process in metal cutting industries. However, it produces fine and ultra-fine metallic particles, also referred to as dust, which can be harmful to the machine-tool operator. The risk associated with exposure to metallic particles increases as the particle size decreases. For machining processes, little data exist on the size and distribution of dust generated during the shaping of materials. In order to reduce or eliminate the generation of these particles, it is necessary to understand how and under which conditions they are formed, as well as to be able to make predictions. In this study, the effects exerted by tool geometry, material, and machining parameters on dust emission were studied experimentally in order to understand the mechanisms of dust generation and to develop a predictive model. The particle sizes studied include the PM2.5 (particles with aerodynamique diameter below 2.5 μm) and a distribution of nanoparticles varying in size from 10 nm to 10 μm. Using dry machining and reducing the amount of dust generated should improve the air quality in machine shops in addition to helping protect the environment.     

Correlation between the adhesive tensile strength and the engagement grade of crosswise oriented nonwovens of metal hook and loop fasteners

Joining is one of the key technologies for industrial products. Nearly all goods need to be joined during their production development process. An innovative joining method such as a metal hook and loop fastener offers new possibilities for the design and functionality of a product. In contrast to a synthetic hook and loop fastener, a metal fastener combines the advantage of a fast assembling or disassembling with the characteristics of a metal joining. The outstanding benefits of the metal hook and loop fastener are temperature and acid resistance. Additionally, features such as shock or sound absorbance can be realized. In this paper, we present the development and characterization of a metal hook and loop fastener. The cohesion of the joining is analyzed by cross tension tests as well as by shearing tests. To draw conclusions from the design of the joining partners, the joining patches are analyzed by neutron μ-CT and compared with force measurements.