Improved bioleaching of copper and zinc from brake pad waste by low-temperature thermal pretreatment and its mechanisms. (15th March 2019)

• Record Type: Journal Article
• Authors: Zhang, Mi; Guo, Xingming; Tian, Bingyang; Wang, Jia; Qi, Shiyue; Yang, Yufei; Xin, Baoping
• Is Part Of: Waste management. Volume 87(2019)
• Page Start: 629
• Page End: 635
• Publication Date: 2019-03-15
• Subjects: Brake pad waste -- Recovery of Cu and Zn -- Bioleaching -- Thermal treatment; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2019.02.047
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Bioleaching is more efficient in the release of both Cu and Zn than chemical means. Low bioleaching of 34% for Cu and 72% for Zn from raw brake pad waste occurred. Bioleaching of 98% for Cu and 100% for Zn from 400 °C-roasted waste was obtained. Huge shift of Cu from residual into oxide/hydroxide by roast caused 98% release. A shift of Zn from residual into acid soluble/oxide/hydroxide caused 100% release. Abstract: A considerable amount of brake pad waste which is composed of phenolic resin and a variety of toxic heavy metals is produced both in China and around the world owing to the flourishing automobile industry. The safe, low cost and eco-sound bioleaching was utilized to extract the valuable metals Cu and Zn from the waste. The results showed that although bioleaching is more efficient in the extraction of Cu and Zn than the chemical counterpart, rather low bioleaching yields of 34% for Cu and 72% for Zn were obtained because of the complicated components and refractory nature of the waste. However, a low-temperature thermal pretreatment at 400 °C notably lifted the bioleaching efficiencies of Cu and Zn to 98% and nearly 100%, respectively. The thermal treatment removed the oil substances, transformed the acid insoluble Cu 0 into acid soluble CuO and destroyed the chelation/complexation of the phenolic resin to loose Cu and Zn, promoting bioleaching performance of Cu and Zn. The combined processes of low-temperature thermal pretreatment and bioleaching is totally qualified for the extraction of Cu and Zn from the refractory waste.