Abstract:

       The carbon sequestration by interaction of mafic tailings with CO2 to form a stable carbonate minerals is a new and
promising method for reducing CO2 emission. The evaluation of CO2 sequestration potential of mafic tailings is the essential premise for the reasonable utilization of these tailings. This paper mainly aims at 10 tailings in two typical ultrabasic rock belts (Donghai-Rizhao rock belt and Chicheng-Chaoyang rock belt) of eastern China, and analyzes mineral components, size distributions and major elements of tailing samples. Then a comprehensive evaluation about the carbon sequestration potential is taken for these mafic tailings in the two rock belts based on analysis results. In the Donghai-Rizhao rock belt, tailings are dominated by the serpentine, with higher MgO content (36.81%-41.39%) and relative coarser sizes. Compared with minerals in Donghai-Rizhao tailings, a variety of hornblende are the common minerals in the Chicheng-Chaoyang tailings, with moderate MgO content (5.84%-15.60%), higher CaO content (5.68%-19.28%) and finer sizes. By field survey and calculation with the chemical equation, the carbon sequestration capacity of Chicheng-Chaoyang tailings is estimated about 4.0×108 t, which is much bigger than Donghai-Rizhao tailings. Considering chemical composition, specific surface area, the tailings resources and other factors comprehensively, mafic tailings in Chicheng-Chaoyang rock belt has the large carbon sequestration potential and can be served as one of the most promising storage sites for carbon sequestration.

Key words: mafic tailings, CO2 sequestration, Mg and Ca content, specific surface area, eastern China