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Why are fine ore, soda, and lime roasted in air during aluminothermic chromium production?
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chromium processing
Chromium.
In the aluminothermic production of chromium, fine ore, soda, and lime are roasted in air at 1,100 °C (2,000 °F) to create a calcine containing sodium chromate. This roasting process is essential because it allows the sodium chromate to be leached from the insoluble gangue, which is then reduced and precipitated as chromium oxide (Cr₂O₃) for the subsequent aluminothermic reaction.1