Enhancement of the Desulfurization Performances of Waste Cement Particles by Acid Treatment

Effect of acid treatment on the desulphurization performances of waste cement particles were examined with a laboratory-scale experimental apparatus based on the weight change of the sample exposed to a gas flow containing SO2. The waste cement particles, a byproduct of recycling process of aggregates from waste concrete, were pre-treated with three kinds of acid, namely, carbonic acid, hydrochloric acid and acetic acid. The desulfurization rate of the waste cement particles was enhanced by the acid treatment; especially, the calcium utilization ratio was significantly improved. In some cases, the desulfurization rate per unit weight of the sample was higher than the original sample. These results can be attributed to the extension of the specific surface area of the particles, and consequently, the ratio of the calcium content active for the desulfurization was increased by the acid treatment. Based on the experimental results, cost estimation of the dry desulfurization process was conducted, and it was found that the desulfurization cost by using the waste cement as a dry sorbent is about 1/10 to 1/6 of that for the conventional method by using limestone. Therefore, the desulfurization process with the waste cement is highly competitive in terms of the cost.