Messages Archive

Subject:
the source of Cr(VI)
Response To:
not knowing anything ... ()

Bill Tindall, E.Tn.
Apparently the chromate comes from slag which comes from iron ore processing. It must be that iron ore that contains chromium forms it in the refining process. As I recall iron oxide ore is heated with limestone and coke. Chromium of some lower valance state must extract into the calcium oxide formed in the slag and at these temperatures becomes oxidized to Cr(VI). Seems backward to me in that the refining process is reducing and Cr(VI) will only form in a highly oxidizing environment. There is obviously some detail of the process I don't understand. In any case the amount is tiny. I never heard of it. Given that only some ore will contain chromium I wonder how wide spread the occurrence is.

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