Lab-scale feasibility of in-situ carbonation of alkaline industrial wastes
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The need for inventive techniques to address current soil- and water pollution problems has sparked research on remediation methods such as accelerated carbonation technology (ACT). However, the majority of research has focused on optimising the process by applying highly enhanced and energy-intensive conditions, thereby making large-scale application unfeasible. The HOMBRE project is working on integrated techniques to make redevelopment of polluted Brownfield areas faster, more profitable and more sustainable. In line with this, the current work investigated the feasibility of accelerated in-situ carbonation of industrial wastes under more ambient conditions with as objective to improve the materials environmental behaviour. Special focus was on stainless steel slags. The experimental research consisted of a full physical and chemical characterisation of the material with subsequent carbonation experiments. Initially, batch experiments were conducted to determine the maximal CO2-uptake of the material whereas in a later stage column carbonation was performed according to a new direct-carbonation set-up. Results indicated that performance of the column set-up was similar to more widely-used methods under similar conditions: a CO2-uptake of 5.5% was found for a reaction time of 8h in the column. Post-carbonation analysis pointed out that treatment indeed had significantly altered the slags mineralogy. The main effects of this were an increased buffering capacity, a reduced alkalinity, and significant changes in the leaching concentration of hazardous metals.