Fine Calcium Carbonate Production By CO2 Mineralization of Industrial Waste Brines | AIChE

Fine Calcium Carbonate Production By CO2 Mineralization of Industrial Waste Brines


La Plante, E., University of California, Los Angeles
Sant, G., University of California, Los Angeles
Wang, B., University of Wisconsin-Madison

Calcium carbonate production via CO2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO2 in a stable form of fine precipitated calcium carbonate (PCC), a high-value product with unit price in the range of $230-$280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinder CO2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) and CO2 generation sources (e.g., power plants), which often renders efficient integration of feedstocks impractical.

To simultaneously address these challenges, a new process is developed to integrate CO2 mineralization-based calcium carbonate production into existing zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serve as the Ca-source. An H+/Na+ ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S. regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants without the need for pretreatment. The CO2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams at low energy input, this process offers significant advantages in energy and CO2 footprint over the traditional high-temperature PCC production. Overall, the new process provides a unique route to integrate CO2 emissions control and wastewater treatment for coal power plants, while producing a high-value product to offset the economic burden.