A Study On CO₂ Sequestration

As one of the greenhouse gases driving global climate change,atmospheric CO₂has brought a lot of negative effects on the earth’s ecological environment.Reducing atmospheric CO₂ concentration has become an urgent task.There are many tailings in China.According to incomplete statistics,there are more than 12000 tailings reservoirs in China,most of which are calcium magnesium silicate minerals,which can make an important contribution to carbon dioxide emission reduction.In this paper,Wanniangou tailings pond in Panzhihua,Sichuan Province is selected as the research object.Combined with the research of mineral composition,element content,chemical characteristics of tailings leaching solution and experimental simulation,the CO₂ sequestration rate and sequestration potential of Wanniangou tailings pond are evaluated.The results are as follows:（1）The total reserve of Wanniangou tailings pond are as high as 1.0008×10⁹ t,of which the main components are feldspar,chrysolite,diopside,albite,chlorite,forsterite,ilmenite and orthoclase,and the proportion of minerals with sequestration potential is 93.16%.The contents of Fe,Ca and Mg in tailings are 13.75 wt.%,4.46wt.%,7.32 wt.%,respectively.The maximum theoretical CO₂ sequestration capacity is 290.4 Mt.（2）The concentration of Ca²⁺and Mg²⁺in the tailings leaching solution is 76.7and 95.4 times of the world river average content,50.5 and 48.2 times of the local upstream river average content,and 1.4 and 3.0 times of the carbonate weathering water in the area,indicating that the chemical weathering of tailing is extremely active.The annual CO₂ sequestration capacity of wanniangou tailing pond is estimated to be about 6644 t.（3）The experimental simulation shows that the dissolution rate of Ca²⁺and Mg²⁺is higher than that of Na⁺and K⁺,and the acid environment is more conducive to the dissolution of Ca²⁺and Mg²⁺,which can promote the CO₂ sequestration reaction of tailings.According to the 48 days leaching experiment data,the mass of CO₂ that can be stored in Wanniangou tailings pond is between 38109.7 t and 56712.5 t in 48 days.