Cleaner recycling of iron from waste copper slag by using walnut shell char as green reductant

Walnut shell is a common agricultural by-products for the production of biochar. In this study, the walnut shell was investigated by thermoanalytical methods to evaluate its thermal behavior; and the biochar was prepared from the pyrolysis at 600 degrees C. Biochar characterization was studied in detail, and proximate analysis result indicates that the biochar obtained from walnut shell has a high fixed carbon content, lower ash content. The biochar was used as a reductant to reduce the waste copper slag for recovering iron. The reduction process of copper slag by biochar was analyzed theoretically, and the iron in the slag was recovered efficiently by reduction and magnetic separation method. The phase transformation of the reduced slag and the kinetics of reduction process were analyzed during the reduction process with biochar. The research results suggest that biochar derived from walnut shell can be used as a green reductant to reduce iron phase in the waste copper slag and realize the clean utilization of hazardous waste. (C) 2019 Elsevier Ltd. All rights reserved.