Effects of Na2O additions to copper slag on iron recovery and the generation of ceramics from the non-magnetic residue

Xinyang Meng; Yu Li; Hongyu Wang; Yindong Yang; Alex Mclean

doi:10.1016/j.jhazmat.2020.122845

Effects of Na₂O additions to copper slag on iron recovery and the generation of ceramics from the non-magnetic residue

J Hazard Mater. 2020 Nov 15:399:122845. doi: 10.1016/j.jhazmat.2020.122845. Epub 2020 May 17.

Authors

Xinyang Meng¹, Yu Li², Hongyu Wang¹, Yindong Yang³, Alex Mclean³

Affiliations

¹ State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
² State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China. Electronic address: leeuu00@sina.com.
³ University of Toronto, Dept. of Materials Science and Engineering, 184 College Street, Toronto, ON, M5S 3E4, Canada.

PMID: 32512277
DOI: 10.1016/j.jhazmat.2020.122845

Abstract

A novel process is proposed in this paper for a green and efficient utilization of copper slag. The basic premise involved the addition of different amounts of Na₂O into molten copper slag and evaluation of the effects on the magnetic fraction and the properties of ceramics generated from the non-magnetic residue, and mechanisms of the effects were further studied by XRD, SEM, EDS, viscosity test, hysteresis loop and FTIR. The results showed that Na₂O additions dropped the viscosity of the slag markedly, which promoted the growth of magnetite, but decrease quantity of magnetite due to oxidization of Fe²⁺ and precipitation of crystals containing Fe³⁺. With the addition of 4 % Na₂O, solidification temperature of slag decreased from 1790 K to 1530 K, optimum iron recovery rate of 81.08 % was achieved. Na₂O as flux in ceramics obviously reduced its sintering temperature and meantime decreased its bending strength because of insufficient crystallization of its main minerals. The non-magnetic residue from magnetic separation of slag with addition of 4% Na₂O was converted into ceramics with a much low sintering temperature of 1268 K (995 °C) and qualified bending strength of 64.5 MPa.

Keywords: Ceramics; Copper slag melts; Iron recovery; Low temperature sintering; Sodium oxide additions.