Metals Recovery from Fine Printed Circuit Boards Using Falcon SB Concentrator

Physical methods show great potential and advantages on comprehensive reutilization of waste printed circuit boards （PCBs） because of lower investment and operation cost, higher efficiency and environment friendliness. However, metals contained in fine fraction of PCBs cannot be recovered effectively by conventional equipments such as high tension electrostatic separator or shaking table. In the paper, this conundrum was resolved successfully with the enhanced Falcon SB concentrator. The separation mechanism of Falcon SB concentrator was analyzed and main factors affecting separation efficiency such as magnitude of rotation frequency of bowl, water counter pressure and slurry concentration of feed were studied and interaction of factors above also were investigated using Design-Expert software. Experiment results show that complete liberation degree and great difference of density between metals and nonmetals are suitable to recover metals from -74μm PCBs using enhanced Falcon SB concentrator and 80.77 % integration efficiency can be achieved when slurry concentration of feed is 40 g/L with the water counter pressure of 0.01 MPa and rotation frequency of 50 Hz.     

Water Hammer Model of Shock Absorber Throttle Slice

In allusion to easy invalidation of damping valve in vehicle shock absorber caused by the impact from the road surface, the importance of the study of damping valve water hammer pressure is presented. The physical model of damping valve with the circle throttle slice is established. The time for the throttle slice deformation is studied by using the finite software, and the laws that how the structure parameters affect the deformation time are obtained. Combining the theory of water hammer, the water hammer initial and boundary condition of the damping valve is deduced, and the water hammer model of throttle slice is established. The analysis of simulation results indicates that the water hammer pressure amplitude and the amount of water hammer oscillation period can be reduced and the dependability of the valve can be enhanced by modifying the structure parameters and aperture width between slice and valve body.     

Dispersive bubble wall——a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall （DBW） is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW＋weir on the flow pattern has been studied. The results show that this new structure of DBW＋weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.     

Progress in the extraction and separation of rare earths and related metals with novel extractants: A review

Rare earths(REs) play a key role in high-tech fields and the associated thorium is a vital element for nuclear energy. However, to be used in high-tech industry or nuclear energy, these elements must first be recovered from the deposits and purified. As solvent extraction is the main technology for the recovery and purification of the metals, the review mainly presents our recent works on the extraction and separation of tetravalent cerium cation by neutral α-aminophosphonates, the individual rare earth separation by α-aminophosphonic acids, and the continuous preparation of high-purity thorium. The extraction and separation of some other metals are also discussed.     

The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration （ MSWI） fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substhtaion, deposition or adsorption mechanisms.     

Characteristics of tailings from metal mines in Hunan Province, China

The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the railings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most railings. The large proportion of heavy metals exists in the form of residual fraction in most railings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the railings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387. 00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.     

Mineralogy and textural impact on beneficiation of goethitic ore

The effect of mineralogy and texture on the beneficiation of goethitic ores from two different origins is highlighted. Sample A having 54.47% Fe with 8.57% loss of ignition(LOI) indicates the presence of vitreous and ochreous goethite, martite and microplaty hematite as the major minerals. Sample B contains 56.90% Fe with 14.4% LOI. There is a pisolithic laterite containing vitreous and ochreous goethite, quartz, kaolinitic clay and there is no hematite mineral. The liberated minerals in -150 + 100μm size class are 74% for Sample A and 37% only for Sample B which shows that the Sample A appears to be more amenable to beneficiate. A concentrate of 46.7% with 63.22% Fe could be recovered from Sample A while subjected to gravity separation followed by wet magnetic separation. The Sample B does not respond to gravity and magnetic separation due to its complex mineralogy. However, calcination of the Sample B followed by magnetic separation gives the encouraging results. Thus, anomalous behaviour of the goethite dominated ores in beneficiation is attributed to the different textural and liberation characteristic.     

Leaching of a copper flotation concentrate with ammonium persulfate in an autoclave system

The leaching behavior of a copper flotation concentrate was investigated using ammonium persulfate （APS） in an autoclave systee. The decomposition products of APS, active oxygen, and acidic medium were used to extract metals from the concentrate. Leaching experiments were performed to compare the availability of APS as an oxidizing agent for leaching of the concentrate under atmospheric conditions and in an autoclave system. Leaching temperature and APS concentration were found to be important parameters in both leaching systems. Atmospheric leaching studies showed that the metal extractions increased with the increase in APS concentration and temperature （up to 333 K）. A similar tendency was determined in the autoclave studies up to 423 K. It was also determined that the metal extractions decreased at temperatures above 423 K due to the passivation of the particle surface by molten elemental sulfur. The results showed that higher copper extractions could be achieved using an autoclave system.     

Separation theory of the incident and scattered sound fields in spherical coordinate

By the spherical wave spectrum transform,the sound pressures on the two spherical surfaces surrounding the scattering objects with arbitrarily-shaped sur-faces are decomposed into spherical wave components that propagate in a known manner,the relationships between the spherical wave components of the same order on the two spherical surfaces are established by the wave field extrapolation theorem,and the formula of the separation theory in the spherical coordinate is established in the wave-number domain. After separating the scattered pressure,the total scattered field can be obtained by holographic reconstruction and predic-tion. In order to overcome the instability of acoustic inverse problem,a new wave-number domain filter technique is proposed. It is proved that,as long as the two holographic spherical surfaces are taken to be close enough,the singularity of the separation formula can be avoided. The results of numerical simulation dem-onstrate the feasibility and validity of the separation theory.     

Effect Of components on desulfurization of an Al2O3-CaO base pre-molten slag containing SrO

The desulfurization experiment of an Al2O3-CaO base pre-molten refining slag containing SrO was carried out. Experimental samples were made from industrial materials. In order to predict the slag‘s desulfurization ability, sulphur capacity was calculated by means of optical basicity, and there is consistency between calculated results and experimental data. A mathematical model between components and sulphur partition ratio was established with the experimental data. Based on the regression equation, the effects of single and interactive components on sulphur partition ratio were discussed. The results show that the sulphur capacity and distribution ratio decrease with the increment of Al2O3/CaO. SrO and MgO can increase the sulphur partition ratio. The best content of SrO in the slag should not be more than 10%, and the MgO content should be about 8%. The effect of CaF2 on sulphur partition ratio is not obvious, therefore the addition should be limited for environmental protection.     

FR4型废弃印刷线路板热解的实验研究

废弃电子印刷线路板含有大量的金属及非金属成分,合理的回收方法不仅可以减少对环境的污染,还能回收大部分金属成分。本文针对FR4型废弃印刷线路板进行了热解处理的实验研究,对其热失重规律、吸热规律、热解残余物等进行了分析,获得了FR4型印刷线路板热解处理的基本规律,对印刷线路板资源化具有重要意义。     

采用磁选和重选回收废旧电路板中的金属

采用磁选和重选联合工艺回收废旧印刷电路板中Fe、Cu、Al、Pb、Zn、Sn和Ni等金属。结果表明,采用干法磁选工艺,可回收的铁磁性物质约占废旧电路板质量分数的8．23％,重液分选可使金属与非金属有效分离,采用磁选和重选联合工艺可使Fe、Cu、Pb、Zn、Ni和Sn的回收率分别达到约100％、80％、65％、75％、88％和56％。     

废弃PCB中铝的涡电流分选研究

介绍了废弃线路板的物理法资源化回收方法,在深入分析线路板物料组成特点的基础上,提出了铝和非金属成份与其它金属成份分离,然后通过涡电流分选方法最终分选出高品位铝产品的技术路线,并作了相关模拟物料实验研究。     

低共熔溶剂提取液、固相环境介质中重金属的研究

当前, 环境介质(土壤, 水体和大气颗粒) 中重金属浓度超标事件频发。如何萃取环境介质的重金属已经成 为当前研究的重要课题。低共熔溶剂(DESs) 是由氢键受体和氢键供体组合而成的两组或两组以上组分的低共熔混 合物, 作为新兴的绿色溶剂, 由于具有绿色环保、可生物降解, 对处理对象损伤性小等优势, 被广泛应用于重金属的 萃取。然而, 关于DESs 对环境介质中重金属的提取的研究仍然缺乏。基于此, 系统综述了DESs 对不同环境介质中 重金属萃取的研究进展, 重点探究DESs 对液相和固相中重金属的萃取机理及效果。结果表明, DESs 对提取液相和 固相中重金属(如Cr、Cd、Cu、Pb、Co、Mn、As 等) 都呈现较好效果。其中氢键供体的羧基和合成DESs 过程中产 生的氢键对重金属的去除起到关键作用, 可处理各种环境介质中重金属。现有的数据表明, 发展DESs 提取重金属 可能是传统处理重金属污染工艺良好的替代方式。     

Underground void filling by cemented mill tailings

Underground mining always create voids. These voids can cause subsidence of surface. So it is always a demand to fill the void in such a manner that the effect of underground mining can be minimized. Void filling using mill tailings especially in metal mining is one of the best techniques. The tailings produced in milling process have traditionally been disposed in tailing ponds creating a waste disposal and environmental problems in terms of land degradation, air and water pollution, etc. This disposal practice is more acute in the metal milling industry where the fine grinding, required for value liberation, results in the production of very fine tailings in large percentage. This paper includes discussions on the effectiveness of different paste mixes with varying cement contents in paste backfilling operations. The results revealed that material composition and use of super plasticizer strongly influenced the strength of cemented backfill.     

我国锤片粉碎机的现状和提高方向

本文简要地阐述了锤片粉碎机的工作原理和影响粉碎效率的因素,讨论了主要技术参数对粉碎机性能的影响。介绍了我国锤片粉碎机发展过程,特别是较前有重大突破的七十年代末期和八十年代初期粉碎机的研制情况、推出的产品、达到的水平和系列化工作的情况。并对锤片粉碎机的制造、安装、操作、管理、工艺设计、工艺流程、吸风配备、传动、自动化以及进一步研完粉碎理论改进机器结构等十个方面提出了个人看法和改进意见。     

基于TRIZ原理的粉碎机锤片结构问题解决方案

利用TRIZ理论中的冲突解决理论和物质-场分析与标准解,提出几种防止锤片磨损、破坏,以及提高粉碎效率、降低粉碎能耗的方案,为设计锤片新结构提供了依据.     

风扇磨煤渣粉碎机锤头抗磨材料的研究

本文针对风扇磨煤粉碎机锤头的磨损特征,应用含15％Cr及3.2～3.6％C的高铬白口铸铁取代普通白口铸铁,使锤头的抗磨能力提高了6.4倍,从而降低了磨煤的生产成本,提高了磨煤质量和生产效率。     

土壤主要组分对多氯联苯吸附及共存Cu2+的影响

采用选择性萃取分离方法对土壤中的主要化学组分锰氧化物、铁氧化物和有机质进行分离,在此基础上,采用批量平衡法研究了25℃下土壤原样、去锰氧化物样品、去铁氧化物样品和去有机质样品对多氯联苯(PCBs)的吸附热力学特征和吸附机理,以及不同含量的共存重金属Cu2+对多氯联苯吸附规律的影响.结果表明:Langmuir和Freundlich吸附模型均可较好地描述多氯联苯在土壤各级样品上的吸附热力学过程.通过比较Langmuir和Freundlich模型所获得的拟合参数可知,土壤各级样品对多氯联苯的吸附规律为:去锰氧化物样品>去铁氧化物样品>土壤原样>去有机质样品.土壤中的有机质和铁氧化物对多氯联苯吸附起主要作用,锰氧化物则抑制多氯联苯的吸附.吸附体系中的共存重金属Cu2+与多氯联苯产生了竞争吸附作用,抑制了土壤各级样品对多氯联苯的吸附,二者之间的竞争吸附作用主要可能发生在铁氧化物和有机质中.