废旧电路板中有色金属的机械物理回收技术

首先从电路板的基本组成、危害性、潜在价值、回收意义方面,阐述了电路板回收的主要特点,接着介绍了机械物理回收法及其优缺点,然后从电路板的拆解、破碎、分选等方面,重点介绍了机械物理回收废旧电路板中有色金属的关键技术和国内外研究现状。     

电子废弃物中贵金属回收新技术

<正>据海外媒体报道,日本研究人员开发出利用树脂提取废旧手机中贵金属的高效回收技术。该技术通过在电子废弃物回收作业时产生的废液中加入特殊的功能性树脂,可提取废液中的金和银等贵金属颗粒,且作业时间短、回收成本低。现行的电子废弃物回收作业大多是利用强酸溶解废旧手机等的电路板,之后通过电还原萃取分离贵金属和稀有金属。对于残留废液中     

我国废旧线路板回收利用与无害化处理技术获得重大进展——首条年处理万吨级废旧线路板成套设备通过鉴定——“电子废弃物”变成“再生资源”成为现实

浙江丰利粉碎设备有限公司研发的FXS废旧电子线路板回收处理成套设备，于2004年12月25日在杭州通过省级新产品鉴定。该设备采用先进的物理法回收工艺：废旧线路板→强力破碎→磁选→中碎→精细粉碎→超微分级→高压静电分离→成品。所研制的强力破碎机、中碎机、精细粉碎机、超微分级机、高压静电分离等设备创新性强，其资源化的处理工艺路线先进合理，能对各类废旧印刷线路板及加工废料、废旧电器等进行机械粉碎回收处理，金属回收率高，回收金属的纯度高达97％。     

废塑料回收装备列入《指导目录》

浙江丰利粉碎设备有限公司开发了废塑料复合材料回收处理成套装备（回收率95％以上）,该设备突破了粉体化回收废塑料、高压静电分选、智能化自动控制和贵金属提取等关键技术,从而有效破解铝塑复合膜、铝塑板、塑料复合膜、     

废旧印刷电路板中电子元器件回收处理技术进展

电子元器件广泛应用于电子电器设备中,但由于产品更新换代和电子电器产业市场的膨胀,大量的电子元器件被丢弃。对电子元器件的资源性和危害性进行分析,综合评述了电子元器件回收利用的最新研究进展和成果,主要包括电子元器件的拆卸技术(解锡方法和分离方法)和回收技术。在此基础上,提出了废旧印刷电路板中电子元器件的无害化和资源化回收研究新动向及发展建议。     

基于循环经济概念下的废弃电路板的再利用

运用循环经济原理,讨论了废弃电路板回收利用的必要性和可行性,并对现有废弃电路板资源化技术进行了分析比较,得出机械-物理处理法是回收利用电路板的最佳选择.针对国外废弃电路板的机械回收利用现状,提出了在国内开展废弃电路板资源化、无害化处理研究的一些建议.     

探究聚氨酯废弃软泡的资源化利用技术(上)

软质聚氨酯泡沫塑料废旧物的回收利用无疑对环境保护和资源利用是有利的,由于聚氨酯的用量较大,而近期原料价格居高不下,其废弃物回收资源化利用市场前景看好。针对废旧聚氨酯软泡塑料的循环利用形势所迫,分别论述了废旧聚氨酯软泡塑料的物理回收利用技术;废旧聚氨酯软泡塑料的化学回收利用技术;废旧聚氨酯软泡回收利用的粘结加压成型和挤出成型技术,以及废旧聚氨酯软泡回收利用热解法制作填料技术等的工艺特点、加工方法,同时指出其社会效益、经济效益和市场前景。     

废旧材料的高温热解回收研究进展

热解是有机物在无氧或缺氧的环境中,通过加热在高温条件下发生分解的反应。废旧材料可以通过热解处理实现资源的循环再利用。废旧材料的高温热解回收不仅能够有效减轻其对环境的污染,而且还可以实现资源的再利用。本文从废旧塑料、废旧塑料/金属复合材料(印刷电路板)、废旧橡胶和生物质四方面分别介绍了高温热解在废旧材料回收利用领域的应用,具体介绍了每种废旧材料的热解过程和热解产物;最后对热解废旧材料的研究所存在的问题和面临的挑战进行了总结和展望,期望对其他废旧材料的高温裂解回收奠定基础。     

废旧印刷电路板回收自动化生产线的评估试验

在现有废旧印刷电路板(WPCBs)机械-物理法回收技术基础上,完善电子元器件(ECs)拆解工艺,利用分级式冲击磨实现粗碎产物的细碎-分离一体化,建立WPCBs回收自动化生产线;分别进行WPCBs拆解试验、废旧印刷电路板基板(WPWBs)粗碎试验和粗碎产物的细碎-金属分离试验;对金属和非金属回收产物进行微观形貌表征;研究分级式冲击磨的分级机转速对金属与非金属回收产物的分离效率的影响;最后对生产线进行了经济性评估。结果表明:该生产线工艺简便,设备投资低,运行能耗低,利润高;产量达到300 kg/h,金属与非金属的分离效率达到94. 4%;回收的铜粉呈球状,其铜品位达95. 4%;符合WPCBs资源化技术的要求,实现WPCBs回收的大规模、工业化生产。     

我国废旧线路板回收利用与无害化处理技术获得重大进展首条年处理万吨级废旧线路板成套设备通过鉴定

<正>浙江省重点省级研发中心、国家重点高新技术企业——浙江丰利粉碎设备有限公司研发的FXS废旧电子路板回收处理成套设备,于2004年12月25日在杭州通过省级新产品鉴定。 专家认为该设备采用了先进的物法回收工艺:废旧线路板→强力破碎→磁选→中碎→精细粉碎→超微分级→高压静电分离     

PARTICLE TRIBOELECTRIFICATION AND ITS USE IN THE ELECTROSTATIC SEPARATION PROCESS

Triboelectrification of solids is known since ancient times. Empirical experiments allow materials to be arranged in so-called “triboelectric series”. Reproducibility, however, is poor in most cases, and the basic mechanisms of the charge transfer are still a subject of speculation. The difference between tribocharging of conductors and insulators is discussed in this paper, and the basic equations for these effects are presented. Triboelectrification of solids has two aspects, one beneficial and one hazardous. The hazardous aspect manifests itself in electrostatic discharges (ESD), which can damage computer equipment, as well as causing fires and explosions during transport and storage of solids and liquids. The beneficial aspect triboelectrification is widely used in many industrial applications, such as the Xerox copying technique, powder coating, pre-charging of fabric filters, electrostatically enhanced cyclone separators, oil mist filtration, aerosol particle collection, and finally, the electrostatic separation of materials. The second part of this paper focuses on industrial electrostatic separation techniques using tribocharging of particles; the separation of potassium minerals, coal beneficiation, and polymer separation for waste processing are presented.     

RECENT PROGRESS IN ELECTROSTATIC SEPARATION TECHNOLOGY

The applications of the electrostatic separation technique employed in the various field was overviewed. By classifying the electrostatic separators with the charging method and with the kind of sorting equipment, recent progress in the electrostatic separators was presented and also future trend was discussed. Principle and practical structure of the separator employing corona charging and induction charging was described in detail. Basically these charging and separation methods are applied to the materials with large difference in conductivities. Triboelectrification has been employed to charge the materials with little difference in conductivities. This is the case of the separation of reusable plastic material from plastic mixture and of minerals or ash contents from coal powder. Triboelectric charging is a key technique and the variety of a tribocharger for coal cleaning was presented. As an example of a practical separator, recent prominent recycling technology of copper and resin from printed wiring boards in the electronic circuits was introduced. Electrostatic remover of tea stalks and foreign objects from product in food industry were also discussed.     

金属材料静电起电理论分析及实验验证

目的减小包装材料在运输过程中产生的静电对周围或包装内电子产品的影响。方法对金属包装材料与空间粒子的摩擦起电机理进行理论分析,以固体接触分离起电为基础推导出摩擦起电电位的计算公式。为验证理论分析的正确性,以铝系金属材料为例进行摩擦起电实验。结果通过理论推导得到材料静电电位随时间以负指数规律增加,并逐步趋近饱和值,该饱和值与材料的性质有关,并与摩擦速度和接触面积成正比。在材料摩擦起电电位测试实验中,所得的静电电位变化曲线与理论分析相同,且连续测试后发现材料起电电位逐次降低;根据不同材料和不同摩擦速度时静电电位饱和值的变化情况,证实了金属材料摩擦起电电位与材料摩擦系数和接触面积的对应关系。结论通过理论分析和材料摩擦起电实验,得到了摩擦起电电位的增长规律,对减小静电危害起到指导意义。     

Triboelectric separation of a starch-protein mixture – Impact of electric field strength and flow rate

Triboelectric separation is a method for separating dry particulate systems due to their different electrostatic chargeability. Previous applications are limited to the separation of coarse powders. The aim of the present study is to examine the influence of the flow conditions and the influence of the electric field strength on the separation efficiency of starch and protein particles. Very fine organic powders are separated in a simple bench scale electrostatic separator to extend this technique to powders below 50?µm. The influence of different gas flow rates in the turbulent flow regime on particle charging and subsequent separation is investigated.As an organic model substrate, a mixture of barley starch and whey protein was used. The tribocharger consists of a PTFE charging tube and a rectangular separation chamber where an electric field is applied between two electrodes. The particles are conveyed through the charging tube and charged by frictional contact with the tube wall. It is shown that different gas flow rates at a turbulent flow regime in the charging tube did not change the separation characteristics. In contrast, increasing electrical field strength increases separation efficiency of protein particles regardless of gas flow conditions. The proportion of starch at the anode is the same for all the investigated parameters.     

Triboelectrostatic separation of granular plastics mixtures from waste electric and electronic equipment

The efficiency of the electrostatic separation of insulating granular mixtures depends on the electric charge carried by the particles. The first objective of this work was to characterize the tribocharging properties of various plastic materials in the composition of waste electric and electronic equipment: polyvinyl chloride (PVC), “high-impact” polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), “high-density” polyethylene (HDPE), polycarbonate (PC), polyamide (PA). Thus, in a first series of experiments, 15 samples composed of binary mixtures of above plastics were initially charged in a fluidized bed device, then separated using a free-fall electrostatic separator. The six plastics could be ordered in a specific triboelectric series: PVC, HIPS, ABS, PEHD, PC, PA. The second objective was to evaluate the efficiency of three tribocharging devices: a static charger, a fluidized bed, and a fan-type device. The triboelectrostatic separation experiments performed with four different binary mixtures (PVC/PA, PC/PA, HIPS/PA, and HIPS/ABS) showed that the fluidized bed is the most effective.     

Fluidized Bed Device for Plastic Granules Triboelectrification

The study of the triboelectrification process is the key factor to the successful industrial application of electrostatic separation in the field of plastics recycling. Therefore, the aim of the present work is to evaluate an original device for the laboratory study of this process. The original design of the fluidized bed type triboelectrification device has the following distinctive features: (i) transparent walls to observe the fluidization process and the particles moving in the triboelectrification module; (ii) air distributors with different mesh apertures correlated with granule size; (iii) quick replacement of the triboelectrification Plexiglas chamber with other metallic (aluminium, copper) or nonmetallic chambers (polyvinyl chloride—PVC, polyethylene—PE, and polyethylene terephthalate—PET); (iv) possibility of independent operation, for granule charge measurement or integrated operation, for the electrostatic separation experiments using a free-fall electrostatic separator. The results of charge measurement experiments pointed out the different triboelectric behaviour of two types of granules (polystyrene and low-density polyethylene) in contact with the walls of the device. The electrostatic separation experiments carried out on a binary mixture of mm-size polystyrene/polyethylene granules confirmed the effectiveness of the triboelectrification device.     

Fluidized Bed Device for Plastic Granules Triboelectrification

The study of the triboelectrification process is the key factor to the successful industrial application of electrostatic separation in the field of plastics recycling. Therefore, the aim of the present work is to evaluate an original device for the laboratory study of this process. The original design of the fluidized bed type triboelectrification device has the following distinctive features: (i) transparent walls to observe the fluidization process and the particles moving in the triboelectrification module; (ii) air distributors with different mesh apertures correlated with granule size; (iii) quick replacement of the triboelectrification Plexiglas chamber with other metallic (aluminium, copper) or nonmetallic chambers (polyvinyl chloride—PVC, polyethylene—PE, and polyethylene terephthalate—PET); (iv) possibility of independent operation, for granule charge measurement or integrated operation, for the electrostatic separation experiments using a free-fall electrostatic separator. The results of charge measurement experiments pointed out the different triboelectric behaviour of two types of granules (polystyrene and low-density polyethylene) in contact with the walls of the device. The electrostatic separation experiments carried out on a binary mixture of mm-size polystyrene/polyethylene granules confirmed the effectiveness of the triboelectrification device.     

RECENT DEVELOPMENTS IN THE SAFETY CONSIDERATION OF ELECTROSTATIC SPRAYING PROCESSES

Etectrostatic coating processes apply high voltages of the order of 100 kV to electrically charge the spraying material which is then precipitated on the surface of the work piece to be coated, making use of the resulting electrostatic attractive forces. A variety of electrostatic spraying equipment is in use, ranging from the hand-held electrostatic spray guns to the large electrostatic installations for painting car bodies. The materials are liquid paint, powders and flock. As these materials are flammable, their use may constitute an ignition hazard. Moreover, as high voltages are applied, there may be the risk of electric shock to persons.

In this survey, the major safety requirements for the prevention of both the risk of ignition and the risk of electric shock are dealt with, due regard being given to the different types of spraying equipment and spraying materials. In addition, special problems such as the use of triboelectric surav nuns or the use of water-based Daints have been given some considerations.

The safety requirements are based on the European Standards EN 50176 and EN 50177 for automatic electrostatic spraying installations and further standards which are still in preparation.     

Axial interface optical phonon modes in a double-nanoshell system

Within the framework of the dielectric continuum (DC) model, we analyze the axial interface optical phonon modes in a double system of nanoshells. This system is constituted by two identical equidistant nanoshells which are embedded in an insulating medium. To illustrate our results, typical II-VI semiconductors are used as constitutive polar materials of the nanoshells. Resolution of Laplace's equation in bispherical coordinates for the potentials derived from the interface vibration modes is made. By imposing the usual electrostatic boundary conditions at the surfaces of the two-nanoshell system, recursion relations for the coefficients appearing in the potentials are obtained, which entails infinite matrices. The problem of deriving the interface frequencies is reduced to the eigenvalue problem on infinite matrices. A truncating method for these matrices is used to obtain the interface phonon branches. Dependences of the interface frequencies on the ratio of inter-nanoshell separation to core size are obtained for different systems with several values of nanoshell interdistance. Effects due to the change of shell and embedding materials are also investigated in interface phonon modes.     

多肽和氨基酸纳滤膜分离中的膜污染及防治研究进展

综述了近期有关多肽和氨基酸的纳滤膜分离过程中的膜污染及防治的研究进展。膜表面浓差极化层或凝胶层的形成以及多肽和氨基酸与膜的疏水或静电吸附是导致该过程膜污染的主要原因，调节溶液的物化条件，改善膜材质的性能和提高亲水性是当前膜污染防治的主要途径。