The goal of this work was to understand how Cr~(6+) formation is affected by the interaction between chromite phases present in magnesite-chrome refractory and different slag compositions. In addition, the formation of Cr~(6+) as a function of chromite particle size and cooling rate due to the chromite phase/slag interaction was investigated. The following slag compositions were studied: calcium aluminate, calcium aluminum silicate, and calcium silicate. It was found that the presence of uncombined CaO in the calcium aluminate slags is responsible for a higher yield of Cr~(6+). However, the replacement of Al_2O_3 by SiO_2 in calcium aluminate slags decreases the formation of Cr~(6+). SiO_2 reacts with CaO to form stable 2CaO.Al_2O_3.SiO_2 and CaO.SiO_2 phases, consequently decreasing the amount of uncombined CaO available to react with the chromite phase to form Cr~(6+). Moreover, the content of Cr~(6+) is decreased by increasing chromite particle size and increasing the cooling rate of magnesite-chrome refractory.
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