Mechanism of arsenic distribution and migration during iron extraction by copper slag-steel slag combined reforming: A potential solution to refractory wastes

Abstract

In this study, a combined reforming and reduction smelting of copper slag-steel slag was proposed to recover iron (Fe) from solid waste while lowering the environmental risks associated with the management of such waste. In this process, copper slag was mixed with steel tailing to sinter, and made into pellets after magnetic separation. These two products were extracted by a smelting reduction process to obtain Fe, with a recovery rate of 98.63% and a grade of 92.91%. The migration and enrichment behaviors of arsenic (As) in the process were studied, and its mechanism was analyzed by X-ray diffraction, electron probe micro-analyzer, and X-ray photoelectron spectroscopy. The sequential extraction procedure was adopted to analyze the occurrence form of the hazardous As in the copper slag, while leaching tests allowed evaluating the environmental risk of the slag upon reduction smelting. The results proved that such reduction slag represent a stable and low-risk material. However, As was dispersed and released in each procedure of the process, potentially propagating its hazards into subsequent processes and life cycles. This study highlights the potential of an alternative route for the treatment of waste copper slag while recovering Fe from it. The reformed copper slag has strong adaptability, and the smelting reduction method exhibits a high recovery rate of Fe and low-risk reduction slag that can be widely used. It provides a valid reference for the safe management of heavy metal emissions and environmental risk awareness and helps to achieve large-scale consumption of copper slag and steel slag.