Abstract
Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy–energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150°C, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.
Highlights
30 million tons of copper slag is annually produced worldwide [1], for China, the leading producer of copper, accounting for nearly one-third of the total [2]
Considerable research efforts have been devoted to the recovery of iron from copper tailings
The concentration of magnetite in the slag is increased from 22% to greater than 85% by this method, which is beneficial for the recovery of iron by magnetic separation
Summary
30 million tons of copper slag is annually produced worldwide [1], for China, the leading producer of copper, accounting for nearly one-third of the total [2]. The bulk iron in copper slag is not effectively recovered on an industrial scale, leading to considerable waste of iron resources. R.M. Jiao et al, Recovery of iron from copper tailings via low-temperature direct reduction and. The high reduction temperature (1200–1300°C) adopted in these studies can lead to sintering, which would be detrimental during the processing of copper tailings in industrial facilities, e.g., in a rotary kiln. The authors of previous studies did not thoroughly examine the mechanism of iron reduction. In this context, the low-temperature reduction of pellets of depleted copper tailings was proposed and the process optimization and the reduction mechanism were investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
