Recycling of minute metal scraps by semisolid processing:Manufacturing of design materials

As a new attempt to recycle minute metal scraps, the possibility of manufacturing design materials by semisolid extrusion processing was shown.A design material with an intended shape, such as a character or petal shape, was manufactured using minute metal scraps.Similarly, a design material with an intended color pattern for each metal, such as red copper in a white aluminum matrix, resembling grainlike wood, was manufactured by mixing two or more types of minute metal scrap.In addition, secondary design materials, which have engraved patterns on the surface of the target metal made by an electric discharge machine using the above primary design material as an electrode, were manufactured.

Failure Mechanisms and Structural Optimization of Shredder Hammer for Metal Scraps

Recycling retired cars can relieve the environmental pollution and resource waste efficiently.However,a few publications can be found on the failure mechanisms and optimization method of recycling equipment,shredders.Thus,the failure mechanisms and structural optimization of shredder hammers for retired cars are studied aiming improving shredding efficiency and reducing cost.Failure types of shredder hammer are studied theoretically,and it is found that wear failure and fatigue failure are the two main failure types of shredder hammer.The shredding process of metal scraps is analyzed by finite element method,and it can be divided into four stages based on the stress states：initial stage,collision stage,grinding stage and separation stage.It is proved that the shredding efficiency can be improved by increasing cutouts on the hammer head.Finally,it is determined that the hammer with two cutouts is the optimal structure for metal scraps,which can improve the shredding efficiency by 20% and lengthen the hammer life by 15%.This study provides scientific basis for the industry application and theoretical foundation for further research.

Trace Metal Leaching from Cookware Locally Fabricated from Scrap Metal: A Case Study of Ntungamo District, Uganda

Heavy metal exposure remains a significant public health problem, particularly in sub-Saharan Africa where use of artisanal cookware made from recycled metallic materials is still common. In this study, the effect of cookware composition, cleaning material, heating duration and temperature on metal migration from different cookware, including artisanal pans was investigated. Trace element concentrations were determined with Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Locally fabricated cookware leached the highest levels of metals, where the levels of Pb (9.00 ± 0.80 × 10-2 mg/l), Al (11.40 ± 0.02 × 10-2 mg/l), Cd (5.80 ± 0.30 × 10-2 mg/l), Cr (6.60 ± 0.03 × 10-2 mg/l) and Ni (3.00 ± 0.01 × 10-2 mg/l) were above the WHO permissible limits of heavy metals for drinking water. Steel wire was the most aggressive cleaning material to the cookware surfaces, followed by sand and then ash. For cookware heated at 100°C and above, an exponential relationship between temperature and the migration of Al, Pb and Cd was observed. The findings revealed heavy metal exposure from cookware usage, which poses potential health risks to the population. There is need for policies and civic education to minimize this exposure.

Smart decontamination device for small-size radioactive scrap metal:using abrasion pin in rotating magnetic field and ultrasonic wave cleaner

A smart decontamination device is developed for small-size radioactive scrap metal(SSRSM)arisen from nuclear facilities.The abrasion pin in rotating magnetic field and ultrasonic wave cleaner are used for solving the problems of the second decontamination and high treatment cost.At first,the decontamination efficiency of each device is improved by upgrading the design.Optimal operating conditions are determined for each device.Next,both techniques are applied sequentially.Experimental results show that the efficiency of combined decontamination device is higher than that of each device.With the use of the developed device,the various SSRSMs are decontaminated for 15 min treatment in magnetic abrasion device and15 min treatment in ultrasonic cleaning device.Decontamination index ranges from18 to 56.Absolute values of all decontaminated samples are below the background value.

Radiological Doses and Risk Assessment of NORM Scrap Metal by Using RESRAD-RECYCLE Computer Code

In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-RECYCLE computer code. Two scenarios were used: the first was the workers’ scenario, while the second was end-use product scenario. Workers’ scenario was used in this study for evaluating the dose and risk to workers who process recycled materials. This scenario focused on the transport of radioactive NORM scrap metal from the place of origin to the smelter (scrap delivery step). Scenarios for six different workers were included under the scrap delivery step: two workers scrap cutter, two workers scrap loader, and two workers scrap truck driver. The values for each scenario were specified on the basis of processing 200 tons of NORM scrap metal. Because these operations occur before melting of the metal, mass and radionuclide partitioning factors were not applied in the scrap metal delivery step. The radionuclide concentration of the NORM scrap metal was used directly in the dose calculation. The maximum doses received from direct external exposure to all radio nuclides during cutter/sorter, scrap truck driver and unloading of scrap metals were 2.14E-04, 1.4E-06 and 1.86E-05 (mSv) respectively. The excess cancer risks for all radio nuclides during cutter/sorter of scrap metals reached 1.25E-07. Radiation exposures incurred by the scrap unloaders and scrap cutters/sorters were greater than those incurred by the other workers for their closer exposure distances and longer time.

铁包加废钢烘烤预热技术研究

针对铁水包加废钢后铁水温降过大、铁水到炼钢工序后温度低的问题展开研究,系统阐述了韶钢自主开发的铁包加废钢预热烘烤系统及其技术。通过该技术成果的应用,消除了铁包加废钢后给铁水能量带来的损失,实现了炼钢铁水温度平均提升22℃、铁钢比降低至750 kg/t的优秀业绩,年创经济效益达500万元以上。

铁包加废钢烘烤预热技术研究

针对铁水包加废钢后铁水温降过大,到炼钢后温度低的问题展开研究,阐述了中南股份自主开发的铁包加废钢预热烘烤系统及技术。通过技术成果的应用,消除铁包加废钢后给铁水能量带来的损失,炼钢铁水温度提升22℃,铁钢比降低至750 kg/t。

Comparison of Soil Samples from Selected Anthropogenic Sites within Enugu Metropolis for Physicochemical Parameters and Heavy Metal Levels Determination

This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples at depths (0 - 20 cm) and (20 - 40 cm) were collected from waste dump sites, metal scrap dumps, fuel filling stations and auto-mechanic workshops and analyzed for physicochemical characteristics and heavy metal levels. Atomic absorption spectrophotometer was used for heavy metal determination while conventional analytical methods were employed for physicochemical parameters evaluation of the soil samples. At soil depths 0 - 20 cm and 20 - 40 cm the respective mean range of pH, electrical conductivity, organic matter and organic carbon contents in the soil samples were, 6.33 - 6.74, 101.46 - 123.21 μS/cm, 6.41% - 8.35% and 13.73% - 16.14% for auto-mechanic workshops;6.92 - 7.43, 56.46 - 60.02 μS/cm, 1.53% - 2.20% and 11.93% - 12.60% for fuel filling stations;7.14 - 7.84, 70.81 - 77.71 μS/cm, 3.81% - 4.12% and 8.57% - 9.24% for metal scrap dumps;6.54 - 6.81, 94.40 - 100.71 μS/cm, 8.83% - 10.75% and 18.26% - 20.81% for waste dump sites. The pH of the top soil samples from auto-mechanical workshop was below the WHO recommended limits for agricultural purposes. The physic-chemical characteristics of the soil samples decreased with soil depths indicating therefore that anthropogenic activities greatly influence the soil characteristics at the top soils than the sub-soils. The electrical conductivity values of top and sub-soil samples from the studied auto-mechanical workshops were above the recommended limits. At soil depths 0 - 20 cm and 20 - 40 cm, the respective mean range of Zn, Pb and Cd in the soil samples were 17.29 - 19.16 μg/g, 0.704 - 0.96 μg/g and 0.26 - 0.33 μg/g for auto-mechanic workshops;4.13 - 4.88 μg/g, 0.21 - 0.32 μg/g and 0.03 - 0.11 μg/g for fuel filling stations;30.02 - 36.11 μg/g, 0.43 - 0.48 μg/g and 0.15 - 0.19 μg/g for metal scrap dumps;9.30 - 10.84 μg/g, 0.53 - 0.60 μg/g and 0.38 - 0.45 μg/g for waste dump sites. The mean levels of Pb in soil samples from mechanic workshops and waste dump sites were above the recommended permissible limits for agricultural purposes. The study therefore indicated that these sites (auto-mechanic workshops and waste dump sites) could be major sources of Pb pollution to nearby farmlands, streams and the general environment. Plants grown on or around these sites may not produce high yields and could be severely contaminated with heavy metals which portend health danger to food consumers within the environment.

废旧硬质合金再生钨资源技术研究进展

硬质合金的广泛使用消耗了大量钨资源,因此,硬质合金再生钨资源技术的研究对于保护钨资源具有重要意义。对目前各种硬质合金回收钨资源方法进行了综述,并简要分析了主流回收技术的特点。同时,针对不同回收技术所制备碳化钨粉末及其合金的应用情况进行了典型分析。最后,对废旧硬质合金行业再生钨资源技术的发展趋势进行了展望。

清远市某五金塑料企业关闭搬迁地块土壤污染状况初步调查分析

本文以清远市某五金塑料关闭搬迁地块为调查研究对象,根据相关国家、地方技术导则和规范,开展地块土壤和地下水污染状况初步调查。本研究地块未来规划属于工业用地。项目组通过对地块开展历史资料收集、现场踏勘及人员访谈,识别出地块内及周边区域当前和历史上可能的污染源,在地块内布设7个土壤监测点和3个地下水监测点,在地块外布设2个土壤对照和1个地下水对照监测点。经现场钻探采样和实验室检测分析,结果显示土壤检测指标检测结果均能满足对应的土壤污染风险筛选值,地下水环境状况基本符合相应环境标准,无须开展详细调查及风险评估工作。

国外有关再生原材料利用情况综述

回顾了近年一些国外发达国家再生原材料使用水平日益提高的整体趋势和法规要求,再生产品管理的目标和措施,以及废钢铁、废有色金属的回收利用情况,旨在推动我国再生原材料推广使用。

废电路板综合回收铜与稀贵金属的研究进展

随着《推动大规模设备更新和消费品以旧换新行动方案》的实施,各类旧手机、旧电脑、旧热水器等报废的旧电子产品日益增多,这类电子废弃物中不仅含有铜等有价金属,还含有害重金属元素,如果不加以利用不仅会造成有价金属浪费,而且会污染环境。鉴于此,简述从废电路板中综合回收稀贵金属的物理化学等方法,并对比各类方法的优缺点,为综合回收废电路板中稀贵金属提供理论方法。

RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

Several typical methods for the recovery of Ni-Cd batteries are described in detail. Based on the comparison between the hydrometallurgical process and the pyrometallurgical process, the latter is selected as the suitable method for recycling Ni-Cd batteries in China.

Comprehensive utilization of metal materials for steelmaking at Baosteel

Optimization of scrap utilization, through maintaining a reasonable heavy scrap ratio, determination of scrap yield, development of substitutes for scrap, recycling of high-alloy scrap and optimization of scrap utilization technology, was investigated in this paper, in terms of the supply of metal materials, production cost, production quality and environment protection. Then, recycling of solid waste resources was discussed, and the utilization conditions and methods of slag-steel, slag-iron, steel-slag, etc. were determined. Finally, the management system for comprehensive resource utilization was introduced.

报废汽车拆解厂大气颗粒物重金属污染特征、来源解析及健康风险评价

利用电感耦合等离子体发射光谱仪(ICP-OES)对从国内某大型报废汽车拆解厂采集的大气颗粒物样品中的8种重金属进行了分析测定,并基于该测定数据对拆解厂区重金属污染特征、来源以及人体健康进行了研究,结果表明,机械破碎区和人工分选区重金属的平均质量浓度相对较高,Pb和Cd的质量浓度超出了GB 3095-2012《环境空气质量标准》的二级标准。正定矩阵因子分解(PMF)模型分析结果表明,拆解厂区中重金属的来源主要包括镀锌钢板材料源、铝合金材料源、含铅材料源、铜合金材料源、汽车涂料源和电镀镍-铬合金材料源。健康风险评价结果显示:Cr对人体健康存在非致癌风险,其他元素的非致癌风险基本可以忽略;Ni和Cd对人体具有潜在的致癌风险,Cr对人体有较明显的致癌风险。研究成果可为报废汽车拆解行业大气颗粒物重金属污染防治提供科学依据。

超声空化作用下高温合金废料中战略金属的浸出机理

为提高高温合金废料中战略金属的回收效率,提出一种超声辅助浸出工艺。在超声辅助浸出过程中,浸出时间为60 min时,高温合金废料中Re、Ni、Co、Al、Cr和W的浸出率分别为92.3%、95.2%、98.5%、98.7%、97.5%和27.2%,明显优于常规浸出工艺中浸出时间为120 min时的浸出效率。高温合金废料中战略金属浸出效率的提高可归因于超声空化作用下产生的物理和化学协同作用。超声空化的物理作用可以阻止高温合金废料表面溶解层的形成,促进浸出液与高温合金废料接触,从而提高高温合金废料中战略金属的浸出率;而超声空化的化学作用可以促进HCl-H_(2)O_(2)体系中羟基自由基的产生,从而增强浸出体系的电位,促进体系中Re向ReO_(4)^(-)的氧化反应过程。

基于CFS-KNN的双能X射线废金属特征优选与分类

在基于双能X射线透射技术的废金属分选中,识别效果很大程度上受所选物料特征影响。已有废金属物料识别算法所用特征不够全面且各特征数据间冗余性较大,识别准确度不高。针对该问题,充分考虑特征间冗余性和特征与类别间关联性提出相关性特征选择方法(CFS),在众多物料特征中确定由特征I_(H)、I_(L)、x、T_(ML)和T_(MH)组成的最优特征子集。通过采用不同物料特征组合方法进行对比实验,并选择最优特征子集下K-最近邻(KNN)作为最优分类模型。实验结果表明:基于相关性特征选择K-最近邻(CFS-KNN)的废有色金属物料识别分类方法与已有分类方法相比用相对较少的特征获得更高的识别准确度(96.13%)。

电感式传感器识别废金属的影响因素研究

基于电感式传感器的金属识别是废金属自动分选的一种新技术,但存在对常见废金属材料难以准确识别与分类的问题。针对铜、铁、铝3种常见废金属识别问题,研究电感传感器参数对金属识别的影响因素及规律。首先,建立电磁感应理论模型,分析废金属识别的影响因素;其次,采用COMSOL Multiphysics电磁仿真软件,研究电感式传感器特性参数对3种废金属的影响规律。采用方差分析法计算各因素对传感器识别不同金属的贡献,为电感式传感器的设计、选型及识别方法研究提供参考。

废金属商品进口、成本加成与中国出口企业利润

文章采用中国工业企业数据库、海关贸易数据库以及HS商品目录下的废金属商品数据,实证分析废金属商品进口对中国出口企业利润的影响及其作用机制。研究显示,中国出口企业进口废金属商品等作为中间投入品进行生产,将显著提高出口企业的利润水平,且该作用是通过提高出口企业成本加成产生的。据此,要完善对废金属商品进口监管,提高进口质量,允许符合国家有关产品质量标准的废金属商品进口,充分利用全球资源,影响国内产品市场竞争程度,不断降低生产成本,提高企业成本加成,从而提升企业利润水平。

银氧化锡合金废料电解综合回收工艺研究

采用直流电解法和化学法回收银氧化锡(AgSnO_(2))合金废料中的银和锡。优化得到的电解银工艺参数为:槽电压1.5~3.0 V,电解周期为24 h,电解液中Ag^(+)浓度为150~260 g/L,HNO3浓度为15~20 g/L,同极距120~140 mm,极板排布为六阴极五阳极间隔交替排列。一个周期银氧化锡废料电解银直收率接近95%,主体纯银粉在阴极析出。富含氧化锡的阳极泥和残极用硝酸浸出少量残余银,不溶渣还原熔炼回收锡,硝酸浸出的含银溶液中加入氢氧化钠调节pH值到10,沉淀得氧化银,500℃焙烧得到单质银。废料中的银和锡均得到有效回收。全流程银的回收率不低于99%。