不锈钢酸洗废液的处理与回收技术综述

介绍了不锈钢酸洗废液的来源、组成和危害.综述了酸洗废液中酸及金属的回收方法、原理及优缺点,着重介绍了酸的扩散渗析、双极膜电渗析、蒸酸和焙烧回收技术,以及金属盐的中和沉淀、析晶、离子交换树脂和萃取回收技术.指出将多种技术进行组合,可实现酸洗废液中金属盐和酸的双重回收.     

废钢破碎线收益能力分析

废钢破碎线是金属资源回收企业的核心生产工艺之一,以废金属和报废汽车等为加工原料,以破碎和分选为核心工艺,是金属回收产业的重要组成部分。作为衔接金属资源回收和金属冶炼产业链的重要环节,废钢破碎线的收益能力是金属资源回收企业提升收益能力、降低运营成本的关键因素。对废钢破碎线的收益能力和影响收益能力的各因素进行分析,构建出函数模型,基于函数模型分析,得出金属资源回收企业在废钢破碎线的筹划、选型、投建、使用、运营维护和管理等方面应该重视的因素。其分析结果为废钢回收企业和报废汽车回收企业投资建设提供参考。     

城市电子废物的资源循环及回收方法探究

电子废弃物资源循环是一系统问题,除电子废弃物收集计划与物流、政策措施外,电子废弃物资源流程结构的建立和资源回收技术是保证.全面分析了电子垃圾中的资源结构,论述了从电子废物中回收材料的各种可行方法,尤其是从电子废物中回收玻璃、塑料和金属的各种再循环技术.如玻璃,讨论了从玻璃-玻璃和从玻璃-铅的再循环技术;如塑料,分析了化学再循环、机械再循环和热量再循环方法;如金属,讨论了铜、铅,以及贵重金属如银、金、铂和钯的回收过程与程序,最后对生物技术在电子垃圾金属回收中的应用这一环境友好的新技术做了介绍.     

从工业废物中回收重金属

介绍了用氧化－铬沉法从特殊钢酸洗废液中回收镍、铁、钼及从镉镍电池废渣中回收镉，镍等金属金属制成多种化合物的原理，工艺流程及结果。     

汽车用铂族金属的循环利用技术简介

铂族金属在地壳中储量稀少。随着汽车销量的增加及汽车尾气排放标准的提高,铂族金属的用量增长迅速。简要介绍了从废旧汽车尾气净化触媒中回收铂族金属的工艺流程及方法,随着研发技术的深入,铂族金属的回收利用率将大幅提升。     

废旧线路板中非金属材料回收利用技术研究进展

总结了废旧线路板中非金属材料的回收意义和回收利用技术研究现状。重点介绍了废旧线路板中非金属材料的物理法、热解法和溶剂法回收利用技术研究进展及其实际应用现状。在此基础上,分析了今后废旧线路板中非金属回收利用技术研究发展趋势。     

加拿大诺兰达公司将废电子产品当成宝

加拿大诺兰达公司近年来非常重视从废弃电子产品中回收铜、银、铂、钯等贵金属. 2000年该公司 70亿加元 (1美元约合 1.57加元 )的营业额中,有 4亿加元来自回收业,而回收业的货源中有 3/4是电子产品. 在诺兰达公司眼中,使用过的电子产品具有极大价值,因为从废弃电子产品中提炼出来的金属数量高于从同等数量的矿石中提炼出来的金属数量. 目前该公司在美国设有 4个回收厂,回收项目包括电脑、打印机、电话、寻呼机和音响设备等. 目前诺兰达公司掌握着北美回收市场的 3/4, 该公司预计今后 5年金属回收的数量将至少增长 1倍.     

从废电池中回收钴和锂的封闭处理工艺

日本某重工业公司开发了一种从废弃的锂电池电极中回收高纯度金属钴的处理工艺。截至日前，除了采用一种昂贵的金属提炼方法外，对从电池中回收的钻进行再利用是非常困难的。     

一种废电池资源化处理方法

该发明涉及一种废电池资源化处理方法，特别针对高污染、高毒性的废弃镍镉电池。将废弃镍镉电池破开处理，经添加助燃物使加热燃烧时炉内产生压力，后经密闭炉间接加热方式使废弃镉镍电池充分氧化，镉金属在600℃气化，将气化的镉金属急速冷凝还原成金属镉回收，而未还原成金属的氧化镉则另外回收，燃烧剩下的铁镍金属再以磁性分离的方式回收。／CN1536706，2004—10-13     

日本从报废手机中提取贵重金属

日本横滨金属公司把报废手机视为“宝贵的矿物资源”，积极从中获取多种贵重金属。 日本目前已有6000多万手机用户，1999年一年间报废的手机多达4000万部。除40%被回收外，报废手机在日本大多被作为一般垃圾扔掉。因此，怎样处理这些废弃物，已成为一个不小的环保问题。 横滨金属公司是一家重金属冶炼企业。在对报废手机成分进行分析后，该公司发现，手机中的贵重金属含量相当丰富。于是，它应用自己拥有的熔炼、电解及化学提取等金属冶炼技术，7年来处理了大约900吨报废手机，从中回收了金、银、铜、钯等多种贵重金属，获得相当可观的经济效益。这家公司说，平均每100克手机机身中，含有14克铜、0.19克银、0.03克金和0.01克钯。另外，从手机锂电池中还能回收锂。     

Thermodynamic analysis of the role of chlorine and sulfur environments during combustion and incineration processes

 In order to control the emission of trace metals from combustion and incineration systems, sorbents and filters are sometimes used. However, the effectiveness of these methods is greatly affected by the volatility of the metals and the way in which they speciate during combustion, and afterwards during condensation, and physical or chemical sorption. Although there has been a lot of research into the mechanisms by which trace metals speciate and subsequently appear in submicron particles, the details of these mechanisms are not yet thoroughly understood. In this study, a chemical equilibrium approach was used to qualitatively determine the speciation of lead, cadmium, and chromium in Cl and S environments. The reaction conditions of sorbents were also tested numerically in order to understand the reaction behavior of metals with sorbents. This article reports the influence of different concentrations of Cl and SO₂ on Pb, Cd, and Cr speciation, as representatives of other trace elements. The partitioning behavior of metals during combustion was also examined for Cl and S. The results obtained indicate that most metals exist in the vapor phase, even at low temperatures, when chlorine is present. However, the addition of SO₂ enhances the formation of the condensed phase, except at extremely high temperatures. This observation was not significant for Cd or Cr. The higher the concentration of Cl the higher the retention of trace metals in the vapor phase, even at low temperatures. Results from comparisons of the reactivities of mixed metals with Cl indicate that the presence of Fe limits the reactivity of most trace metals with Cl except at higher concentrations. In the presence of Fe, alkali metals are the first to react with Cl. If Fe is not present, most trace metals react with Cl, and the activity increases with higher concentrations. On the other hand, the partitioning characteristics of S show that its presence generally means that metals remain in the condensed phase. Sulfur is more reactive with alkali metals than with other trace metals. Received: June 6, 2001 / Accepted: April 30, 2002     

A dynamic leaching method for the assessment of trace metals released from hydraulic binders

With respect to sustainable development, the leachability of trace metal from solid materials in contact with water has focused much attention over the years. Portland cements produced in industrial kilns generally contain from 10 to 300 mg/kg of trace metals. The behaviour of these endogenous metals has been, in this regard, the target of different leaching studies. Many of these researches concluded that heavy metals release are lower than analytical detection limits. Although satisfying from an environmental point of view, it induces a lack in the knowledge about the trace metals behavior during the leaching of cement based material. Accordingly, we designed the CTG-LEACHCRETE device, a dynamic leaching system (modified Soxhlet type) that overcomes this difficulty and allows long term monitoring. The experimental procedure is presented and preliminary results are discussed.     

Characteristics of element distributions in an MSW ash melting treatment system

Thermal treatment of municipal solid waste (MSW) has become a common practice in waste volume reduction and resource recovery. For the utilization of molten slag for construction materials and metal recovery, it is important to understand the behavior of heavy metals in the melting process. In this study, the correlation between the contents of elements in feed materials and MSW molten slag and their distributions in the ash melting process, including metal residues, are investigated. The hazardous metal contents in the molten slag were significantly related to the contents of metals in the feed materials. Therefore, the separation of products containing these metals in waste materials could be an effective means of producing environmentally safe molten slag with a low hazardous metals content. The distribution ratios of elements in the ash melting process were also determined. The elements Zn and Pb were found to have a distribution ratio of over 60% in fly ash from the melting furnace and the contents of these metals were also high; therefore, Zn and Pb could be potential target metals for recycling from fly ash from the melting furnace. Meanwhile, Cu, Ni, Mo, Sn, and Sb were found to have distribution ratios of over 60% in the metal residue. Therefore, metal residue could be a good resource for these metals, as the contents of Cu, Ni, Mo, Sn, and Sb in metal residue are higher than those in other output materials.     

Treatment of mixed contamination in water using cyclodextrin‐based materials

This study investigated the effectiveness of a cyclodextrin‐based solid material for the removal of mixed dissolved contaminants. The solid material was prepared by condensation of α‐cyclodextrin. The removal efficiency was found to be 70 percent for total heavy metals (cadmium, lead, chromium, iron, nickel, cobalt, and mercury) to 98 percent for polychlorinated biphenyls (PCBs). The optimum pH for heavy metal removal was approximately 5 and for PCBs it was in the range of 5–7. All of these heavy metals were successfully recovered from the spent cyclodextrin‐based material using nitric acid, allowing the material to be reused for further passes. The results also showed that the presence of alkaline and alkaline earth metals did not have a significant effect on the removal efficiency, indicating that the cyclodextrin‐based material could selectively remove the heavy metals of concern without being consumed by alkaline and alkaline‐earth metals. © 2006 Government of Canada.     

Determination of Cu and Ni incorporation ratios in Portland cement clinker

Cu and Ni are metals found in galvanic sludges; these sludges are considered hazardous due to their heavy metal content. The main objective of this work is to determine the incorporation amount of Cu and Ni in Portland clinker when a galvanic sludge containing these metals is added to the clinker raw-material. The influence of this addition on the clinkering reactions is evaluated as well as the possibility of co-incinerating galvanic sludges containing Cu and Ni in rotary cement kilns. This study also characterizes the galvanic sludge. Samples were prepared by additions from 0.25 to 5 wt.% of a galvanic sludge to an industrial clinker raw-material. The clinkering process was simulated in a laboratory device. The following techniques were applied to characterize the raw materials and the products of the tests: chemical analysis, differential thermal analysis (DTA) and thermogravimetric analysis (TG). Leaching tests were performed in the produced clinker samples in order to verify the incorporation of the studied metals in the clinker structure. The results led to the conclusion that additions of up to 2 wt.% of a galvanic sludge containing 2.4 wt.%Cu and 1.2 wt.% Ni to clinker raw-material do not affect the clinkering reactions and that these metals are totally incorporated into the clinker.     

Conflicting processes in the wetland plant rhizosphere: Metal retention or mobilization?

Increasingly wetlands are used for treatment of metal-contaminated water or as a cover over metal-enriched mine tailings. Natural wetlands may also be contaminated with metals from anthropogenic sources. While wetland conditions tend to be favorable for immobilization of metals, wetland plants could influence metal mobility through redox and pH processes in the rhizosphere. Our current knowledge of these processes is reviewed, focusing on the question of whether the advantages of growing wetland plants in metal-contaminated sediments outweigh the disadvantages. Wetland plants alter the redox conditions, pH and organic matter content of sediments and so affect the chemical speciation and mobility of metals. Metals may be mobilized or immobilized, depending on the actual combination of factors, and it is extremely difficult to predict which effects plants will actually have on metal mobility under a given set of conditions. However, while the effects of plants can extend several tens of centimeters into the sediments, there are no reports suggesting large-scale mobilization of metals by wetland plants.     

再谈废催化剂中金属的回收

介绍了含钯,钴,钼,钨的废催化剂的来源及从废催化剂中回收上述金属的工艺。     

The effect of accelerated carbonation on the properties of cement-solidified waste forms

Ordinary Portland cement blended with blast furnace slag and pulverised fuel ash was used to solidify two industrial wastes containing large amounts of metals. The solidified mixes were carbonated using an accelerated regime previously established and compared for strength development, leaching characteristics and phase development against their non-carbonated analogues. A significant difference in the immobilisation of metals such as Zn, Ni and As was recorded for samples in which carbonation was optimised. The work has shown that by controlling mix parameters it is possible to improve the immobilisation of specific metals. Electron microanalysis showed that this is partly due to the precipitation of calcite in the solidified waste pore structure. Carbonation was also found to accelerate C₃S hydration in all carbonated samples and to modify the morphology of residual cement grains through the formation of a calcite coating over de-calcified hydration rims. Some metals appear to be incorporated in both of these zones.     

Sources of heavy metal contamination in Swedish wood waste used for combustion

In this paper, wood waste (RWW) recovered for heat production in Sweden was studied. Previous research has concluded that RWW contains elevated amounts of heavy metals, causing environmental problems during waste management. This study extends previous work on RWW by analysing which pollution sources cause this contamination. Using existing data on the metal contents in various materials, and the amounts of these materials in RWW, the share of the elevated amounts of metals in RWW that these materials explain was quantified. Six different materials occurring in RWW were studied and the results show that they explain from 70% to 100% of the amounts of arsenic, chromium, lead, copper and zinc in RWW. The most important materials contributing to contamination of RWW are surface-treated wood, industrial preservative-treated wood, plastic and galvanised fastening systems. These findings enable the development and evaluation of strategies aiming to decrease pollution and resource loss from handling RWW. It is argued that source separation and measures taken further downstream from the generation site, such as treatment, need to be combined to substantially decrease the amount of heavy metals in RWW.     

Metal leachability, heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in fly and bottom ashes of a medical waste incineration facility

Medical waste from hospitals and other healthcare institutions has become an imperative environmental and public safety problem. Medical waste in Greece has become one of the most urgent environmental problems, because there are 14,000 tons produced annually, of which only a small proportion is incinerated. In the prefecture of Attica there is only one modern municipal medical waste incinerator (started 2004) burning selected infectious hospital waste (5-6 tons day(-1)). Fly and bottom residues (ashes) are collected and stored temporarily in barrels. High values of metal leachability prohibit the landfilling of these ashes, as imposed by EU directives. In the present study we determined quantitatively the heavy metals and other elements in the fly and bottom ashes of the medical waste incinerator, by inductively coupled plasma emission spectrometry (ICP) and by energy dispersive X-ray analysis (EDAX). Heavy metals, which are very toxic, such as Pb, Cd, Ni, Cr, Cu and Zn were found in high concentrations in both fly and bottom ashes. Metal leachability of fly and bottom ashes by water and kerosene was measured by ICP and the results showed that toxic metals in both ashes, such as Pb, Cr, Cd, Cu and Zn, have high leaching values. These values indicate that metals can become soluble and mobile if ash is deposited in landfills, thus restricting their burial according to EU regulations. Analysis of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in fly and bottom ashes showed that their concentrations were very low. This is the first known study in Greece and the results showed that incineration of medical waste can be very effective in minimizing the most hazardous and infectious health-care waste. The presence of toxic metals with high leachability values remains an important draw back of incineration of medical waste and various methods of treating these residues to diminish leaching are been considered at present to overcome this serious technical problem.