Carbonation Behavior Assessment of RH Slag Batch after Aqueous Extraction at Environmental Pressure

Abstract

In order to assess CO2 sequestration amount and carbonation degree for RH slag at surrounding pressure, carbonation process of RH slag batch in lab is investigated, and the parameters of carbonation degree and CO2 sequestration amount are the targets, and the relationship between both and relevant factors, such as CO2 flow, gas bubble size etc. is originally discussed. The carbonation degree increases when temperature increases before 60 °C, then decreases. Particle size has a positive effect on carbonation degree, and carbonation degree for 0.5 L/min is bigger than those for 0.1 L/min and 1.0 L/min. When small gas bubble generator is adopted, carbonation degree and CO2 sequestration amount is improved. The maximum carbonation degree and CO2 sequestration amount is 34% and 178.65 g/kgslag, respectively when 38 μm RH slag batch is carbonated for 90 min at 60 °C under the conditions that CO2 flow is 0.5 L/min and bubble size equals 5 mm. CaCO3 and MgCO3 phases exists through XRD analysis, showing that carbonation process is effective. Carbonation degree model is established assuming carbonation reaction occurs on the active surface of RH slag batch. This model fits very well by comparison between experimental results and model results.