Abstract
Argon oxygen decarburization stainless steel slag (AOD slag) has high mineral carbonation activity. AOD slag carbonation has both the resource utilization of metallurgical waste slag and the carbon reduction effect of CO2 storage. This paper aimed to study carbonation reaction characteristics of AOD slag. Under the slurry-phase accelerated carbonation route, the effect of stirring speed (r) and reaction temperature (T) on AOD slag’s carbonation was studied by controlling the reaction conditions. Mineral composition analysis and microscopic morphology analysis were used to explore the mineral phase evolution of AOD slag during the carbonation process. Based on the unreacted core model, the kinetic model of the carbonation reaction of AOD slag was analyzed. The results showed that the carbonation ratio of AOD slag reached its maximum value of 66.7% under the reaction conditions of a liquid to solid ratio (L/S) of 8:1, a CO2 partial pressure of 0.2 MPa, a stirring speed of 450 r·min−1, and a reaction temperature of 80 °C. The carbonation reaction of AOD slag was controlled by internal diffusion, and the calculated apparent activation energy was 22.28 kJ/mol.
Highlights
AOD slag is a by-product of the secondary refining process of stainless steel using argon-oxygen decarburization process
AOD slag generally exists as a fine powder with a light gray color, its main chemical components include CaO, SiO2, and MgO, with mass fractions of 57.72%, 31.69%, and 6.68% [1], and the main mineral phases are calcite (CaCO3 ), dicalcium silicate (Ca2 SiO4 ), pyroxene (CaMg(SiO3 )2 ), with mass fractions of 41.0%, 40.4% and 14.2% [2]
According to the estimation of 1 ton of stainless steel slag associated with every 3 tons of stainless steel [3], the global stainless steel slag output in 2020 will be approximately 16.96 million tons
Summary
AOD slag is a by-product of the secondary refining process of stainless steel using argon-oxygen decarburization process. As of 2020, the global stainless steel output has reached 50.89 million tons. According to the estimation of 1 ton of stainless steel slag associated with every 3 tons of stainless steel [3], the global stainless steel slag output in 2020 will be approximately 16.96 million tons. AOD slag contains heavy metal elements such as Cr, Pb, Ni, etc. [4] shows that improper disposal will cause the waste of rare heavy metal resources such as Cr, Pb, and Ni, etc. As the output abandoned AOD slag increases year by year, most of its disposal methods are stacking and landfilling, causing environmental pollution and land waste [5,6]. How to effectively treat and use AOD slag has become a hot spot for domestic and foreign attention and research
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