Environmental characterization of ferrochromium production waste (refined slag) and its carbonization product

This paper presents the results of research on the method of utilization of self-disintegrating slags of refined ferrochrome production by autoclave carbonization in carbon dioxide environment. The work has a complex character, including earlier laboratory studies of the slag carbonization process under different conditions, as well as studies of chemical and mineralogical composition of initial waste slags taken from the slag dump and samples of bricks subjected to carbonization. The composition of slags and obtained products was investigated by XRD, DTA, DTG and XRF analyses, which showed that the main phases of the studied samples are dicalcium silicate, montichelite, periclase, magnesiochromite, calcite. Thermal analytical studies showed that magnesium carbonate is present only in the samples of artificially carbonized material. Also, the process of carbonate formation in the thickness of bricks during forced carbonization was investigated. As a result, it was obtained that with increasing CO₂ pressure, the amount of bound carbon in the products increases proportionally in all layers. It was determined that the amount of CO₂ absorbed during carbonization can reach 20 % of the mass of the initial slag. Stale slag can be used simultaneously as a carbon dioxide absorber and as a building product.