Upgrading nonferrous metal scrap for recycling purposes

Reusing materials in the post-consumer phase of a product is very important; however, it is often difficult to separate the metals, resulting in a scrap that is high in impurities and limited in application. To prevent the mixing of scrap, separation at the source is required. Recently, several techniques for separating nonferrous metals have become available, including eddy-current separation to separate nonferrous metals from a mixture of waste, fluid-bed separation to separate light and heavy metals, and image analysis to separate cast and wrought alloys. For more information, contact G.H. Nijhof, Nijhof Consultancy, Heemsteedse Dreef 92, 2102 KN Heemstede, Netherlands; telephone 31-23-529-2273; fax 31-23-529-2273; e-mail nijhof. consultancy@wxs.nl.     

Inclusions in molten magnesium and potential assessment techniques

Magnesium has increasingly gained acceptance in structural applications, particularly in the automotive industry. The fast-growing applications of magnesium have led to the generation of a large amount of magnesium scrap, especially die-casting scrap. Due to both economic and environmental concerns, recycling of these scraps is imperatively demanded. In order to yield high-quality recycled magnesium, the characteristics of inclusions in molten magnesium have to be identified, and techniques to evaluate the cleanliness of molten magnesium must be developed. This article reviews recent developments in characterizing inclusions and assessing the cleanliness of molten metals. The potential application of these techniques to molten magnesium is also discussed.     

Recycling used automotive oil filters

Over 400 million used automotive oil filters are discarded in the United States each year, most of which are disposed of in landfills wasting valuable resources and risking contamination of ground- and surface-water supplies. This article summarizes U.S. bureau of Mines research evaluating scrap prepared from used automotive oil filters. Experimental results show that crushed and drained oil filters have a bulk density that is higher than many typical scrap grades, a chemical analysis low in residual elements (except tin due to use of tin plate in filters), and an overall yield, oil-filter scrap to cast steel, of 76% to 85%, depending on the method used to prepare the scrap.     

Recycling light metals from end-of-life vehicle

The amount of aluminum used in cars and light trucks is growing steadily. However, without new developments in aluminum recycling technologies, sheet from automotive aluminum could eventually flood all current markets for recycled aluminum. This article summarizes the use of light metals and different alloys in transportation applications, the current auto recycling system, and new developments in the sorting of light metals by the metal recycling industry and by Huron Valley Steel Corporation, the world’s largest non-ferrous scrap sorter. For more information, contact A. Gesing, Huron Valley Steel Corporation, 41000 Huron River Drive, Belleville, Michigan 48111; (734) 697-6313; fax (734) 697-3420; e-mail gesinga@hvsc.net.     

等温淬火球铁(ADI)在汽车底盘零件上的应用

介绍了ADI的性能特点、汽车底盘铸件对材料性能的要求、ADI在美国汽车上的应用情况以及在我国一汽集团和东风汽车集团公司的试用情况,指出了国内中、重型汽车底盘零件应用ADI所存在的问题是:(1)产品设计人员和主管领导对ADI不了解;(2)ADI产业链尚未完全形成。对汽车ADI底盘零件生产的两种不同工艺流程进行了对比,并提出了以自身机加工厂为主体组建ADI产业链的建议。     

Recycling of automotive aluminum

With the global warming of concern, the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits. In this work, recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling, use of aluminum alloys in automotive applications, automotive recycling process, and new technologies in aluminum scrap process. Literature survey shows that newly developed techniques such as laser induced breakdown spectroscopy (LIBS) and solid state recycling provide promising alternatives in aluminum scrap process. Compared with conventional remelting and subsequent refinement, solid state recycling utilizing compression and extrusion at room or moderate temperature can result in significant energy savings and higher metal yield.     

Recycling automotive magnesium scrap

Magnesium die castings have been experiencing tremendous growth in the automotive market for ten years. The European guideline for disposing of old automobiles has had a lasting effect on magnesium recovery and recycling. This article will review the European guideline for automobile disposal and the current technologies used to recycle magnesium scrap from automotive components.     

废旧印刷电路板的粉碎性能及资源特征

采用颚式破碎机或辊式破碎机均难以实现对废旧印刷电路板的充分粉碎,从粉碎过程来看,具有剪切和冲击作用的圆盘粉碎机或振动磨样机的粉碎效果要优越一些.废旧印刷电路板的资源组成包括47%的金属、27%的塑料以及26%的玻璃、陶瓷等难熔氧化物.与天然资源相比,废旧印刷电路板中的金属含量特别丰富,1 t中的金属含量分别达到了300 g Au、5～10kg Ag、19.66%Cu、3.93%Pb和3.68%Sn,此外还含有Fe、Al、Zn、Ca、Mn、Ni、h等十多种有价金属,具有重要的回收价值.     

The recovery of metals from electronic scrap

Most of the published literature on the recycling of scrapped electronic devices is listed in chronological order in Table I. In the 1970s and early to mid-1980s, the predominant method of recycling was blast furnace smelting in conjunction with secondary copper or lead smelters. Since the mid-1980s, the trend has shifted toward the hydrometallurgical processing of scrap. The emphasis has always been on the recovery of precious metals, namely gold, silver, platinum and palladium, from electronic scrap for their obvious economic values. In recent years, greater importance has been placed on the recovery of all metals, including low-concentration metals such as cadmium, because of increasingly strict environmental controls. The electronic scrap recycling program of the 1990s will ha ve to meet many objectives—efficient recovery of all metals, strict effluent and emission controls, the use of nontoxic reagents, maximum recycling of chemical reagents, and minimum energy requirements—in an economical and environmentally safe manner.     

失效汽车尾气催化剂中铂族金属回收的研究进展

失效汽车尾气催化剂是回收铂族金属(铂、钯、铑)的重要二次资源。本文介绍了失效汽车尾气催化剂中铂族金属的回收工艺流程,包括失效催化剂预处理、铂族金属富集、分离与精炼三部分;详细介绍了两种高效预处理技术、两种富集方法以及四种分离与精炼工艺,总结了各种方法的原理、工艺流程、优缺点及改进方向。回收企业应根据回收规模和环保政策采用合适的回收工艺,以实现不同回收工艺之间的优势互补,未来需重点研发回收率高且环境友好的清洁回收工艺。     

压铸高危镁合金废料回收技术与设备研发

镁合金压铸件的广泛应用,特别是在汽车和3C领域的应用的快速增长,不可避免地产生大量的镁合金废料.其中,体积小、比表面积大的易燃废料(压铸高危镁合金废料)的回收问题一直困扰着压铸企业.为此推介了一种真空蒸馏回收压铸高危镁合金废料的技术和设备.分析了镁合金的真空挥发和结晶的技术条件及其对回收效率的影响.同时对设备的工作原理、使用情况和技术经济指标作了介绍.     

Leachability and fractionation of heavy metals in stainless steelmaking plant dusts

The leachability and fractionation of the selected heavy metals (Cr, Cd, Pb and Zn) in the stainless steelmaking plant dusts were studied by the modified HJ/T299-2007 method, the modified TCLP test and a seven-step sequential extraction procedure. The results show that the stainless steelmaking plant dusts are considered as hazardous materials since at least one of the leachable heavy metals exceeds the corresponding limit levels of State Environmental Protection Administration of China. Pb is the most extractable heavy metals by the sequential extraction procedure, while Cr, Cd and Zn mainly presents in the residual fraction bound to spinel phase and silicates. The mobile heavy metals in the dusts, which present as the species of water soluble, exchangeable species and the species bounded to carbonates and hydroxides, can be estimated as 0.08-1.2% of Cr, 7.6%-31.8% of Cd, 34.1% of Pb, 0.052-0.4% of Zn, respectively.     

ENVIRONMENTAL FRIENDLY ANODIZING ON AZ91D MAGNESIUM ALLOYS AND COATING CHARACTERISTICS

An environmental fn‘endly anodizing treatment (Anomag) from a phosphate-based solution without heavy metals on AZ91D magnesium alloy was studied. The characteristics of the coatings, such as structure, composition and corrosion resistance were investigated. The effects of this anodizing treatment on the mechanical properties were examined. X-ray diffraction (XRD) analysis revealed that the structure of the coatings is amorphous or glass. In salt spray tests coatings with an average thickness of 10μm had an anticorrosive performance of over 1000 hours. Fatigue tests revealed that anodizing onto AZ91D magnesium aUoy does not affect the fatigue strength. These results demonstrate the utility of this anodizing treatment on magnesium alloy for application as a structural material, such as in the automotive field.     

从钯废料中回收钯的实验研究

我国铂族金属储量低,钯的二次资源回收利用意义显著。以多种不含银的钯合金废料为原料,针对钯合金废料中钯含量不同这一特点,选取不同的工艺对其中的钯进行了回收。考察了液固比、反应时间对钯浸出率的影响,并对钯和杂质分离及还原步骤下的试剂消耗量进行了考察,所得还原产物经X荧光分析,钯纯度大于99.3%,按原料中钯含量计,其回收率超过96%。     

Life-Cycle Assessment of the Recycling of Magnesium Vehicle Components

Life-cycle assessment is basically the assessment of a product from the cradle to the grave. Ideally, a product is recycled after its useful life is complete and the end-of-life of the first life cycle leads to the beginning of a new product system. For the end-of-life of magnesium vehicle parts, there are various possible paths to a second life cycle. When magnesium parts are dismantled or magnesium is separated after shredding, the resulting magnesium alloys can be used for secondary, noncritical applications. However, the typical case for magnesium components is that the magnesium postconsumer scrap ends up in the nonferrous metals fraction that consists primarily of aluminum, magnesium, and heavy metals. Today, aluminum is typically fed into a second life cycle as a secondary alloy, and magnesium becomes part of the aluminum cycle as an alloy addition. In this article, we evaluate the environmental effects of using magnesium in the aluminum cycle. We also assess the influence of end-of-life scenarios on the overall environmental impact of a component’s life cycle. The primary focus of our analysis is the evaluation of the effects of magnesium vehicle components on greenhouse gas emissions.     

Recovering and recompounding polypropylene from lead-acid automotive batteries

Materials recycling has to satisfy a number of criteria, including: it must not harm the environment; it should produce almost no residue; it should create high-level products with definable lifetimes; and it should be economical. With these requirements in mind, this article describes the reuse of plastic scrap recovered from spent automotive batteries. Necessary development work for separating, treating and recompounding polypropylene is described. Numerous tests have been performed on the resulting molding compounds in order to specify the materials and their processability.     

Isolation,characterization and extraction of mer gene of Hg~(2+) resisting strain D_2

Mercury-resistant strain D2 was isolated from mercury-contaminated soil and investigations on its 16S rDNA sequence,growth,minimal inhibitory concentrations(MICs) of metals,antibiotic susceptibility and mer gene were conducted.The strain D2 can grow in the medium containing 60 mg/L mercury ion.It presents more than 99% identity of 16S rRNA gene with Pseudomonas aeruginosa,and exhibits high MIC values for heavy metals and a large spectrum antibiotics resistance.The mer RT gene sequence was amplified from chr...     

Modeling of Alternative Compositions of Recycled Wrought Aluminum Alloys

Nowadays, a significant part of postconsumed wrought aluminum scrap is still used for the production of comparatively cheaper cast alloys, in that way losing an important part of the potential added value. The share of postconsumed scrap in wrought aluminum alloys could be increased either by sorting to fractions with the required chemical composition and/or by broadening the standard compositional tolerance limits of alloying elements. The first solution requires hand or automatic sorting of postconsumed scrap as alloys or groups of alloys to the degree of separation sufficient to enable the blending of standard compositions of wrought alloys; the second solution is much more radical, predicting changes in the existing standards for wrought aluminum alloys toward nonstandard alloys but yet having properties acceptable for customers. In this case, the degree of separation of incoming postconsumed scrap required is much less demanding. The model presented in this work enables the design of optimal (standard and nonstandard recycling-friendly) compositions and properties of wrought aluminum alloys with significantly increased amounts of postconsumed scrap. The following two routes were modeled in detail: (I) the blending of standard and nonstandard compositions of wrought aluminum alloys starting from postconsumed aluminum scrap sorted to various degrees simulated by the model and (II) changing the initial standard composition of wrought aluminum alloys to nonstandard “recycling-friendly” ones, with broader concentration tolerance limits of alloying elements and without influencing the selected alloy properties, specified in advance. The applied algorithms were found to be very useful in the industrial design of both procedures: (I) the computation of the required chemical composition of the scrap streams obtained by sorting (or, in other words, the postconsumed scrap sorting level), necessary for achieving the standard wrought alloy composition and (II) the transformation of standard to nonstandard (recycling-friendly) compositions with the key alloy properties (e.g., tensile strength and elongation) remaining the same.     

汽车尾气净化Pd催化剂的研究现状、进展及展望

阐述了汽车尾气净化Pd催化剂的技术特点、现状及展望,分析了Al2O3、稀土氧化物对汽车尾气净化Pd催化剂性能的影响,对比了不同制备方法的优异性,讨论了单Pd催化剂的可行性和实用价值,以及未来的研究方向、技术难点和热点.