A review of mineral carbonation by alkaline solidwaste

Abstract

Anthropogenic activities represent a major cause of substantial carbon dioxide emission into the atmosphere, which has given rise to the phenomenon of global warming over the last decades. In this respect, it is of significance to utilize novel technologies to reduce and remove carbon emissions. Mineral carbonation is a sequestration method that can fix CO2 in alkaline materials permanently. Carbon Capture and Storage (CCS) is one method of reducing carbon emission. It is, mainly, a three-step process: (a) CO2 produced at power stations or industrial plants/places is captured; (b) it is transported by ships, tracks, or pipes; and (c) in the storage step, CO2 is injected into underground rocks or to the depth of the oceans to be stored permanently. CCS is currently used on a smaller scale for economic reasons. Carbon Capture and Utilization (CCU) may solve this problem. In this method, CO2 is captured at power plants, like coal-fired plants, to be reused in producing valuable products. CCU and CCS can be applied to ensure direct and indirect carbonation. Alkaline solid wastes containing Ca and Mg including red mud, cement waste, steel slags, potassium waste, copper waste, and MSWI are utilized in capturing CO2. Industrial wastes are highly suitable for carbonation because they are accessible at industrial plants and do not need costly pre-treatments. Besides, industrial alkaline wastes are hazardous to the environment due to heavy metal contamination (e.g., Se, Mo, V), especially if they are released in water resources or in case the slags are scattered through the wind. Moreover, storing these materials is too costly; alternatively, they can be used in carbonation processes. CO2 neutralizes these alkaline materials, thus resolving two issues at the same time. A diverse range of experiments, each with a different efficiency rate, have been conducted to implement the carbonation process under different conditions. This study presented a comprehensive review of the mineral carbonation process by alkaline industrial waste and the capacity of each of the methods and conditions required for the operation. Energy balance and mass balance were investigated to compare different alkaline industrial wastes as a source for the carbonation process.