School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, China; Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, NSW, 2007, Australia.
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, China; Hubei Key Laboratory of Mineral Resources Processing & Environment, Wuhan, 430070, China.
J Environ Manage. 2022 Aug 1;315:115150. doi: 10.1016/j.jenvman.2022.115150. Epub 2022 Apr 27.
Metal-laden solid wastes (e.g., waste graphite powders) have attracted great attention owing to their hazardous effects on the surrounding soil and water. Additionally, the metal-bearing impurities also hinder the reutilization of waste graphite powders. Thus, it is necessary to remove these inorganic impurities and figure out the removal mechanism of impurities in the purification process. In this study, an alkaline roasting-water washing-acid leaching (AWA) method was used to upgrade the waste graphite powders, and the migration behavior of diverse impurities has been qualitatively and quantitatively investigated. A graphite product with high impurity removal efficiencies is attained under optimal conditions. The removal of impurities mainly follows three routes: (1) V-, P-, and S-bearing impurities were complete removed (some formed soluble salts during alkaline roasting, and the remainder was dissolved in acid); (2) most Al-, K-, and Si-bearing impurities were removed by alkaline roasting, with the remainder was dissolved in the acid-leaching process; and (3) Fe-, Mg-, Ti-, Ca-, and Zn-bearing impurities were decomposed at high temperature and reacted with alkali to form hydroxides or oxides, which was subsequently dissolved in acid. In addition, the treatment of the generated wastewater is also discussed. The uncovered migration mechanisms of diverse impurities would guide the purification and reutilization process of other metal-bearing solid wastes efficiently.
载金属的固体废物（例如废石墨粉末）因其对周围土壤和水的有害影响而引起了极大的关注。此外，含金属的杂质也阻碍了废石墨粉末的再利用。因此，有必要去除这些无机杂质，并研究杂质在净化过程中的去除机制。在这项研究中，采用碱性焙烧-水洗-酸浸（AWA）方法对废石墨粉末进行升级，并定性和定量研究了各种杂质的迁移行为。在最佳条件下，获得了具有高杂质去除效率的石墨产品。杂质的去除主要遵循以下三种途径：（1）含 V、P 和 S 的杂质被完全去除（部分在碱性焙烧过程中形成可溶性盐，其余部分溶解在酸中）；（2）大部分含 Al、K 和 Si 的杂质通过碱性焙烧去除，其余部分在酸浸过程中溶解；（3）含 Fe、Mg、Ti、Ca 和 Zn 的杂质在高温下分解并与碱反应形成氢氧化物或氧化物，然后溶解在酸中。此外，还讨论了生成废水的处理。揭示各种杂质的迁移机制将有效地指导其他含金属固体废物的净化和再利用过程。
