Department of Industrial Engineering and Information and Economy, University of L'Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L'Aquila, Italy.
Waste Manag. 2013 Nov;33(11):2364-71. doi: 10.1016/j.wasman.2013.07.006. Epub 2013 Aug 1.
This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2(2) full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3M of sulphuric acid, 10% v/v of H2O2 concentrated solution at 30% v/v, 10% w/w pulp density, 70°C and 3h of reaction. Two series of precipitation tests for zinc are carried out: a 2(2) full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2-2.5% and 10-12%v/v of Na2S concentrated solution at 10%w/v. In these conditions the coprecipitation of yttrium is of 15-20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75-80%.
这项工作专注于从阴极射线管（CRT）荧光粉中回收钇和锌。金属通过硫酸在过氧化氢存在下提取。根据 2(2)完全析因设计进行浸出试验，在以下条件下观察到钇和锌的最高提取率达到 100%：3M 硫酸、30%浓度的 10%v/v 过氧化氢浓缩溶液、10%w/w 浆体密度、70°C 和 3h 的反应时间。进行了两系列锌沉淀试验：2(2)完全析因设计和完全随机析因设计。在这些系列中，研究的因素是沉淀过程中溶液的 pH 值和沉淀硫化锌所需的硫化钠用量。这些试验的数据用于通过回归分析描述锌和钇沉淀产率的两个经验数学模型。在以下条件下获得了最高的锌沉淀产率：pH 值等于 2-2.5%和 10-12%v/v 浓度为 10%w/v 的硫化钠浓缩溶液。在这些条件下，钇的共沉淀率为 15-20%。最后，在去除锌后，对残余溶液进行草酸进一步沉淀钇的实验表明，可以回收和煅烧钇以获得最终产品氧化钇。所取得的结果允许提出一种基于从阴极射线管荧光粉浸出和沉淀去除锌后回收氧化钇的 CRT 回收工艺。最终的钇回收率为 75-80%。
