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电子废弃物壳体塑料分选技术研究

发布时间:2018-04-28 20:23

  本文选题:电子废弃物 + 废塑料 ; 参考:《西南交通大学》2015年硕士论文


【摘要】:2014年,全球产生了4.18×1010kg的电子废弃物,我国是电子废弃物的主要产生地,电子废弃物中含有重金属以及多氯联苯和多溴联苯醚等有机污染物,资源化过程容易发生二次污染,对生态环境造成严重的影响。电子废弃物是“城市矿产”的重要组成部分,利用化学法、物理法和生物法等技术可以提取有色金属和稀贵金属,实现电子废弃物的环境价值和经济价值,因此,电子废弃物是我国循环经济重要组成部分。家用电器和电子设备中包含种类繁多的塑料,约占家电总重的11-60%。由于塑料价格远低于金属,因此,我国长期以来一直呈重金属轻塑料的局面。塑料再生具有重要的资源、环境效益,不仅降低原生塑料生产过程能源消耗,而且节约石油等资源,同时再生制品本身具有一定的经济效益。不同种类的塑料熔化温度不同,熔化参合时相互之间化学不相容,造成混合塑料的材质性能指标差,影响废塑料的循环利用,电子废弃物壳体塑料种类繁多,对其直接进行再加工会影响加工产品的质量和性质。因此,为了达到电子废弃物壳体塑料高值化利用,前提条件是实现塑料纯化,利用分选技术得到高纯度的单一塑料。润湿剂可以降低分选液的表面张力,也可以吸附于塑料表面改变塑料表面化学特性,使塑料被分选液选择性润湿;针对包含PET的混合塑料,经过碱液和添加剂的处理,可以扩大PET与其他塑料亲疏水性之间的差异。本研究利用密度分选技术和浮选技术分选混合塑料,深入探讨了介质和润湿剂对密度分选效果的影响,进一步优化了密度分选工艺参数;研究了润湿剂和添加剂等助剂对浮选结果的影响,建立了浮选助剂体系,研发分选技术体系,为电子废弃物壳体塑料分选技术工业化提供了技术支撑。本研究选取9种常用的塑料分组混合,利用密度分选技术进行分离,其中,分组情况分别为第1组PVC(或POM或PET)/PC、第2组PC/PA6、第3组PA6/PS(或ABS)、第4组PS(或ABS)/HEPE、第5组HDPE/PP,讨论了介质种类、密度以及润湿剂对密度分选结果的影响,结果表明,可通过CaCl2溶液(1.30g/mL)、NaCl溶液1.16g/mL)、NaCl溶液(1.09g/mL)、自来水(1.00g/mL)和C2H5OH溶液(0.90g/mL)逐级分选PVC(或POM或PET)、PC、PA6、PS(或ABS)、HDPE和PP,其中,30mg/L的壬基酚聚氧乙烯醚系列7醚(NP-7)有助于提高PVC、POM、PC和PS的分选率,所有塑料的分选率均达100%。在最佳的密度分选助剂体系下,通过调节密度分选槽的工艺参数,可使90%的目标下沉料进入槽体的收集区,实现连续式密度分选。分选第1组至第5组混合塑料的最佳流量分别为8.5L/min、8.0L/min、5.0L/min、9.0L/min和11.0L/min,分选第1组至第5组混合塑料的最佳搅拌速率分别为500rpm/min、400rpm/min、500rpm/min、 250rpm/min和500rpm/min,密度分选技术体系得到构建。利用浮选技术分选PET/PC/PS和PET/PVC/PS两组混合塑料,.第一步先从混合塑料中分离PS,利用60mg/L的十二烷基硫酸钠(SDS)溶液作为浮选液,经过30min润湿,在合适的浮选设备条件下使PS分选率达100%;第二步是分选PET/PC或PET/PVC,利用1-3mol/L的NaOH溶液和8mmol/L的癸二酸二丁酯(DBS)溶液对混合塑料分别进行预处理,处理时间分别为30min和15rmin,在适当的浮选条件下, PET/PC或PET/PVC成功分离,其中,PC的上浮率为97%,PVC的上浮率为93%,PET的下沉率为96%。
[Abstract]:In 2014, 4.18 * 1010kg of electronic waste was produced in the world. China is the main production site of electronic waste. There are heavy metals in the electronic waste and organic pollutants such as polychlorinated biphenyl and polybrominated biphenyl ethers. The process of resource utilization is easily polluted by two times. The electronic waste is a "urban mineral". The important components of the system are the use of chemical, physical and biological techniques to extract nonferrous metals and rare precious metals, and to realize the environmental and economic value of electronic waste. Therefore, electronic waste is an important part of China's circular economy. Because the price of plastic is far lower than metal, the situation of heavy metals and light plastics has been present in our country for a long time. Plastic regeneration has important resources and environmental benefits. It not only reduces energy consumption in the production process of primary plastics, but also saves oil and other resources. At the same time, the recycled products have some economic benefits. Different kinds of products have different kinds of economic benefits. The melting temperature of the plastics is different, and the chemical incompatibility between the melting and joining is made. The material properties of the mixed plastic are poor, the recycling of the waste plastic is affected, and there are a wide variety of plastics in the electronic waste shell. The direct reprocessing will affect the quality and quality of the processed products. The precondition is to purify the plastic and obtain the single plastic with high purity by the separation technology. The wetting agent can reduce the surface tension of the separation liquid, and can also adsorb on the plastic surface to change the chemical surface chemical properties of the plastic, and make the plastics be wetted selectively by the separation liquid; the needle is mixed with PET, through the alkali solution and the additive. The difference between the hydrophobicity of PET and other plastics can be expanded. In this study, the density separation technology and flotation technology are used to separate the mixed plastic. The influence of the medium and wetting agent on the density separation effect is discussed, the density separation process parameters are further optimized, and the flotation results are studied. The flotation auxiliaries system was established and the separation technology system was developed to provide technical support for the industrialization of electronic waste shell plastics separation technology. This study selected 9 kinds of commonly used plastic groups and separated by density separation technology. Among them, the grouping situation was divided into first groups of PVC (or POM or PET) /PC, second groups of PC/PA6, third groups of PA 6/PS (or ABS), fourth groups of PS (or ABS) /HEPE, and fifth groups of HDPE/PP, discuss the influence of the type of medium, density and the wetting agent on the density separation result. The results show that the CaCl2 solution (1.30g/mL), NaCl solution 1.16g/mL), NaCl solution (1.09g/mL), tap water and aqueous solution are selected. S), HDPE and PP, among which, 30mg/L's nonyl phenol polyoxyethylene ether series 7 ether (NP-7) helps to improve the separation rate of PVC, POM, PC and PS. The separation rate of all plastics can reach 100%. under the best density sorting assistant system. By adjusting the process parameters of the density sorting trough, 90% of the target sink can be entered into the collection area of the tank, and the continuous type can be realized. The optimum flow rate of first to fifth groups of mixed plastics was 8.5L/min, 8.0L/min, 5.0L/min, 9.0L/min and 11.0L/min respectively. The optimum mixing rate of the mixed plastics from first to fifth groups was 500rpm/min, 400rpm/min, 500rpm/min, 250rpm/min and 500rpm/ min, and the density separation technology system was constructed. Flotation technology was used. PET/PC/PS and PET/PVC/PS two groups of mixed plastics were selected. The first step was to separate PS from the mixed plastic, and the twelve alkyl sodium sulfate (SDS) solution of 60mg/L was used as the flotation liquid, and the PS separation rate was 100% under the 30min wetting condition. The second step was to separate PET/PC or PET/PVC, and the NaOH solution and 8mmol/L of 1-3mol/L were used. The two butyl sebacate (DBS) solution was pre treated with 30min and 15rmin respectively. Under appropriate flotation conditions, PET/PC or PET/PVC was successfully separated, of which the floating rate of PC was 97%, the floating rate of PVC was 93%, and the subsidence rate of PET was 96%..

【学位授予单位】:西南交通大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:X705

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