Mineral sequestration of CO2 from Vernasca Ca-looping demo system: scale up to a pilot

Abstract

In recent years, carbon sequestration into thermodynamically stable carbonates has been developed as a promising carbon capture, utilization and storage (CCUS) method, especially, when alkaline industrial wastes are used as sorbents. The use of industrial wastes to sequester CO2 plays a dual role in environment protection, creating opportunities not only for capture and disposal of CO2 but also for recycling of wastes and promoting the transition to circular economy. The CLEANKER project (Horizon 2020 Project Clean clinker production by Calcium looping process) aims to build a CO2 mineralization pilot incorporated into Ca-looping demo system in Vernasca cement plant and use the re-carbonated wastes in concrete applications. Different types of wastes such as burnt oil shale (BOS) from Eesti, Balti and Auvere power plants as well as from Enefit280 oil producing unit in Estonia, concrete demolition wastes (CDW), cement by-pass dust (CBD) from Robilante, Italy, blast furnace slag (NSF) from Bremen, Germany were tested first in laboratory scale via dry and wet direct carbonation routes under the conditions of CO2-rich model gas flow of 70 – 100% CO2, simulating the Ca-looping system. The results show that selected types of BOS and cement wastes could be used as efficient binders in both dry and wet CO2 mineralization systems with binding capacities up to 0.18 kg of CO2 per kg of BOS and up to 0.24 kg of CO2 per kg of CBD. The activating effect of hydration as a pre-treatment method showed that at lower operating temperatures, the same level of CO2 capture can be achieved, thereby rendering the carbonization processes of similar industrial wastes more energy efficient. Moreover, the CO2 mineralization tests with BOS in a 46 L concrete mixer confirmed the applicability of wet carbonization process also in larger scale. Based on the results, the most promising materials, BOS and CBD, were selected for in the proposed CO2-mineralization process in wet conditions at ambient temperature. The pilot (200 L) was designed based on a commercially available concrete mixer integrated into CLEANKER Ca-looping demo system and equipped with CO2 inlets and outlets, as well as CO2, temperature and moisture sensors to detect the reaction progress. The re-carbonated wastes will be tested via concrete casting in order to demonstrate the quality of the commercial product in the following stages of the project.