Abstract
Concentrating the chromium in chromium slag and improving the chromium–iron ratio is beneficial for the further utilization of chromium slag. In this paper, chromium slag obtained from a chromite lime-free roasting plant was used as the raw material. Pellets made of the chromium slag and pulverized coal were reduced at different pre-reduction temperatures and then separated by a melting separation process or magnetic separation process, respectively. The mass and composition of the metallized pellets before separation, along with the alloy and tail slag after separation, were comprehensively analyzed. The experimental results showed that the output yield of alloy, iron recovery rate, and chromium content in the alloy were all higher when using melting separation than when using magnetic separation, because of the further reduction during the melting stage. More importantly, a relatively low pre-reduction temperature and selection of magnetic separation process were found to be more beneficial for chromium enrichment in slag; the highest chromium–iron ratio in tail slag can reach 2.88.
Highlights
Chromium has been widely applied in many industrial processes, such as leather tanning, electroplating, and mineral extraction
For the magnetic separation process, when the pre-reduction temperature increased from 1373 K to 1523 K, the average distribution ratio of iron increased from 0.14 to 0.25
In order to increase the chromium–iron ratio in the chromium slag generated by the chromite lime-free roasting process, carbothermal reduction, followed by the melting/magnetic separation process, was adopted and studied in this research
Summary
Chromium has been widely applied in many industrial processes, such as leather tanning, electroplating, and mineral extraction. About 10% of the chromium remains in the chromium slag and contains water-soluble, migratory, and carcinogenic Cr6+, which is harmful to the environment [6,7,8]. If it is not recycled or reused, are resources wasted, but serious pollution of the environment results, which will have a serious impact on the health of the surrounding residents because of the toxic Cr6+ content of the slag [9,10,11]. It is valuable to explore further treatment methods for chromium slag
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