Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration

CO2 utilization for concrete production: Commercial deployment and pathways to net-zero emissions

Approximately 10 % of global anthropogenic CO2 emissions arise from the cement and concrete industry driven by urban expansion and a constant need for infrastructure renewal. Reusing waste CO2 to make new construction materials produces circular carbon flows and constitutes a key step toward a carbon-negative economy. To establish a holistic view of the field, this paper examines upscaled technologies with industrial deployments for utilizing CO2 in manufacturing cement-based materials and analyzes their interplay for attaining net-zero emissions (NZE) in the concrete sector. By scrutinizing the status quo, it suggests that NZE agendas should be diversified catering to the wide-ranging built products. Small-sized precast elements and lightweight components lead the way in carbon-neutral manufacturing, while the market-dominating ready-mix concrete is by far difficult to decarbonize and relies on the incorporation of pre‑carbonated ingredients, preferably sourced from alkaline wastes, to leverage large-scale CO2 utilization. To expedite the race to NZE, it is necessary to combine the development of CO2 utilization and low-CO2 cement to create decarbonization strategies tailoring for individual products. In this regard, the paper reveals credible pathways and research needs to facilitate their implementation in sustainable construction.

Potential of major by-products from non-ferrous metal industries for CO2 emission reduction by mineral carbonation: a review

By-products from the non-ferrous industry are an environmental problem; however, their economic value is high if utilized elsewhere. For example, by-products that contain alkaline compounds can potentially sequestrate CO₂ through the mineral carbonation process. This review discusses the potential of these by-products for CO₂ reduction through mineral carbonation. The main by-products that are discussed are red mud from the alumina/aluminum industry and metallurgical slag from the copper, zinc, lead, and ferronickel industries. This review summarizes the CO₂ equivalent emissions generated by non-ferrous industries and various data about by-products from non-ferrous industries, such as their production quantities, mineralogy, and chemical composition. In terms of production quantities, by-products of non-ferrous industries are often more abundant than the main products (metals). In terms of mineralogy, by-products from the non-ferrous industry are silicate minerals. Nevertheless, non-ferrous industrial by-products have a relatively high content of alkaline compounds, which makes them potential feedstock for mineral carbonation. Theoretically, considering their maximum sequestration capacities (based on their oxide compositions and estimated masses), these by-products could be used in mineral carbonation to reduce CO₂ emissions. In addition, this review attempts to identify the difficulties encountered during the use of by-products from non-ferrous industries for mineral carbonation. This review estimated that the total CO₂ emissions from the non-ferrous industries could be reduced by up to 9-25%. This study will serve as an important reference, guiding future studies related to the mineral carbonation of by-products from non-ferrous industries.

Aqueous mineral carbonation of ultramafic material: a pre-requisite to integrate into mineral extraction and tailings management operation

Ex situ aqueous mineral carbonation of ultramafic mining waste is an evolving technology for the CO₂ sequestration from small- to medium-scale emitters. The mineral ores or mine wastes of associated ultramafic mineralogy are a suitable feedstock for mineral carbonation. The aqueous mineral carbonation at ambient temperature is motivating and attractive from an energy-saving perspective. This study has investigated the CO₂ sequestration potential of a locally available ultramafic material generated from a nickel ore mine with a futuristic scope of integrating the method into an ongoing mineral extraction and/or tailing management operation. The mineral characterization and experimental results indicate that the tested material has CO₂ sequestration potential and underwent carbonation at ambient temperature. The carbonate conversion efficiencies obtained for Ca and Mg from the dissolved ionic forms at optimum conditions are 60% and 25%, respectively. The material was able to sequestrate about 0.12 gCO₂ per g solid at this efficiency. Aragonite and hydromagnesite are the major products that evolved out from the aqueous carbonation. Based on the mineral carbonation results, the novel concept of integrating the evolved method to existing mineral extraction and/or tailings management operation is discussed.