Development of a New CO₂ Sequestration Process Utilizing the Carbonation of Waste Cement

Abstract

We propose a new sequestration process for anthropogenic carbon dioxide (CO 2 ) that uses waste cement. The proposed process consists of two main reactions. The first is the extraction of calcium ions (Ca 2+ ) from waste cement particles by pressurized carbon dioxide (several megapascals of pressure). The second is the precipitation of calcium carbonate (CaCO 3 ). Ca 2+ extracted from waste cement is deposited as CaCO 3 when the pressure is reduced. CaCO 3 is disposed of directly, or recycled as a raw material for cement production. In the latter case, the same amount of CO 2 is considered to be sequestered because the net amount of virgin limestone mined can be reduced. The power consumption and cost of the proposed sequestration process for CO 2 emitted from a 100 MW thermal power plant were evaluated, on the basis of laboratory-scale experimental results. The power consumption for the operating process strongly depended on the operating conditions such as the cement/water ratio, the CO 2 pressure, and the average cement diameter. The minimum power consumption was 25.9 MW/100 MW of power generation when optimized within the operating conditions studied experimentally, and the sequestration cost associated with the power consumption (excluding capital and maintenance) would be about $22.6/t of carbon dioxide. This result indicates that the present process is highly competitive with previously reported CO 2 sequestration scenarios such as ocean sequestration. Sensitivity analysis of the operating parameters was carried out on the operating power consumption, and it was found that a smaller ratio of waste cement to water and a lower CO 2 pressure will decrease the operating power consumption.

Carbonate-bonded construction materials from alkaline residues

“…Materials that have been considered for carbonation include ash from coal-fired power plants (CaO content up to 65 wt-%), bottom ash (~10 to 20 wt-% CaO) and fly ash (~35 wt-% CaO) from municipal solid waste incinerators, de-inking ash from paper recycling (~35 wt-% CaO), steelmaking slag (~30-60 wt-% CaO and MgO), and waste cement or concrete [30][31][32][33][34].…”

Comparison of Two Processes Forming CaCO3 Precipitates by Electrolysis

“…In this perspective, it was assumed that Process 2, for which the reaction conversion rate was 10% higher than Process 1, captured more CO 2 . Furthermore, the final product of Process 2 can process more CO 2 than that of Process 1, and can be used as raw material for construction materials [26].…”

Generation, Capture, and Utilization of Industrial Carbon Dioxide

“…On depressurization CaCO 3 is deposited, which can be reincorporated into the cement-making process. [18] Ammonia production Although ammonia contains no carbon, it is manufactured from carbon feedstocks such as natural gas, naphtha, coke, or coal, heavy fuel oil and petroleum gas.…”