Research On The Comprehensive Evaluation System For Recovery Process Of Wasted LCDs

According to relevant research, the amount of waste electronic and electrical appliances in China is expected to increase2-4times by2020, in which flat televisions, desktop computers and laptops have accounted to nearly70%. As the key components of display products, wasted LCDs (Liquid Crystal Displays) have been drawning more attention. Many universities and research institutes have already been researching into the recovery mechanism of wasted LCDs and developed recovery processes. However, till now there are no scientific and objective evaluation rules to assess those processes. This paper established a set of comprehensive evaluation system for recovery process of wasted LCDs based on the LCA(Life Cycle Assessment) theory.First,the theory and mathematical model of LCA were represented. And considering actual condition in our country, three sets of LCIA (Life Cycle Inventory Assessment) methods most frequently used in China-CML2001, Ecoindicator99and EDIP97, were specially explicated in three aspects:environmental impact classification, modeling method and weighting coefficient. This is the first step for the recovery process assessment.The recovery process was divided into three attributes-economic, environmental and technical. The starting point of economic aspect was the cost and benefit of those process and related indicators such as cost benefit ratio were put forward. LCA was used to evaluate the environmental effects. The technical aspect contained macro factors and microfactors. The Douglas function was essential to analyze macro factors and as the result capital input efficiency, per capital output efficiency and corresponding coefficient of elasticity were applied. And the value of recovery rate was essential to analyze microfactors. After all the indicators had been prepared,3-scale AHP (Analytic Hierarchy Process) method was set up for the comprehensive evaluation of LCD recovery process then calculated the best plan.The new evaluation system would be used for the recovery process. The recovery of wasted LCDs included three main stages-the extraction of liquid crystal, the enrichment of precious metal indium and the recycling of glass substrate. The extraction of liquid crystal contained supercritical oxide method and distillation method. The enrichment of indium adopted acid leaching-distillation method and glass substrate would be used as additional material of new glass. The results showed that:(1) recycling wasted LCDs was more environmental friendly than the simply incineration of LCDs;(2) for the extraction of liquid crystal, the comprehensive evaluation results of supercritical dioxide method was better than distillation method and more applicable;(3) the extraction of liquid crystal and the enrichment of indium would cause obvious environmental problems of Acidification Potential (AP) and Global Warming Potential (GWP). This was mainly because the use of organic solvents and acid-base solutions. So it is necessary to improve the solvents’ utilization rate and the recycling work.In order to make the evaluation system adapt to the changes of market, a model based on Fuzzy Bayesian function was also established in the paper.