Pita Fernando, Castilho Ana
Geosciences Centre, Department of Earth Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal; Centre for Mechanical Engineering, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal.
Waste Manag. 2016 Feb;48:89-94. doi: 10.1016/j.wasman.2015.10.034. Epub 2015 Nov 7.
Plastics are popular for numerous applications due to their high versatility and favourable properties such as endurance, lightness and cheapness. Therefore the generation of plastic waste is constantly increasing, becoming one of the larger categories in municipal solid waste. Almost all plastic materials are recyclable, but for the recycling to be possible it is necessary to separate the different types of plastics. The aim of this research was to evaluate the performance of the jig separation of bi-component plastic mixtures. For this study six granulated plastics had been used: Polystyrene (PS), Polymethyl methacrylate (PMMA), Polyethylene Terephthalate (PET-S, PET-D) and Polyvinyl Chloride (PVC-M, PVC-D). Plastics mixtures were subjected to jigging in a laboratorial Denver mineral jig. The results showed that the quality of the jigging separation varies with the mixture, the density differences and with the size and shape of the particles. In the case of particles with more regular shapes the quality of separation of bi-component plastic mixtures improved with the increase of the particle size. For lamellar particles the influence of particle size was minimal. In general, the beneficiation of plastics with similar densities was not effective, since the separation efficiency was lower than 25%. However, in bi-component plastic mixtures that join a low density plastic (PS) with a high density one (PMMA, PET-S, PET-D, PVC-M and PVC-D), the quality of the jigging separation was greatly improved. The PS grade in the sunk was less than 1% for all the plastic mixtures. Jigging proved to be an effective method for the separation of bi-component plastic mixtures. Jigging separation will be enhanced if the less dense plastic, that overflows, has a lamellar shape and if the denser plastic, that sinks, has a regular one.
由于塑料具有高度的通用性以及诸如耐用性、轻便性和廉价性等优良特性，因此在众多应用中广受欢迎。所以，塑料废弃物的产生量在不断增加，成为城市固体废弃物中占比较大的类别之一。几乎所有塑料材料都可回收利用，但要实现回收，就必须将不同类型的塑料分开。本研究的目的是评估跳汰分选双组分塑料混合物的性能。在本研究中，使用了六种粒状塑料：聚苯乙烯（PS）、聚甲基丙烯酸甲酯（PMMA）、聚对苯二甲酸乙二酯（PET-S、PET-D）和聚氯乙烯（PVC-M、PVC-D）。将塑料混合物在实验室的丹佛矿物跳汰机中进行跳汰分选。结果表明，跳汰分选的质量随混合物、密度差异以及颗粒的尺寸和形状而变化。对于形状较为规则的颗粒，双组分塑料混合物的分选质量随颗粒尺寸的增加而提高。对于片状颗粒，颗粒尺寸的影响最小。一般来说，对密度相近的塑料进行选矿并不有效，因为分选效率低于25%。然而，在将低密度塑料（PS）与高密度塑料（PMMA、PET-S、PET-D、PVC-M和PVC-D）混合的双组分塑料混合物中，跳汰分选的质量有了很大提高。对于所有塑料混合物，沉底部分的PS含量均低于1%。事实证明，跳汰是分离双组分塑料混合物的有效方法。如果溢出的密度较小的塑料呈片状，而沉底的密度较大的塑料呈规则形状，跳汰分选效果将会增强。
