Synthesis and performance control of calcium carbonate based on wet carbonation of carbide slag

ZHANG Saisai; ZHANG Xinyu; SHEN Yuanyuan; ZHU Jianping; LIU Songhui; GUAN Xuemao

doi:10.16186/j.cnki.1673-9787.2023110045

Abstract：Objectives To fully utilize the carbide slag(CS)generated during the acetylene gas production process and solve the pollution problem associated with CS storage,while achieving CO2 sequestration,the feasibility of using the wet carbonation method to control the synthesis of different calcium carbonate poly-morphs from CS was studied.Methods First,under room temperature conditions,the effects of different CO2 aeration rates on the wet carbonation process of CS were investigated,resulting in the synthesis of calcite-type calcium carbonate.Then under 80 ℃ conditions,magnesium chloride was used as a polymorph controller to synthesize aragonite-type calcium carbonate.X-ray Diffraction(XRD),thermogravimetric analysis(TG),scanning electron microscopy(SEM)and other methods were used to characterize the com-position and morphology of the carbonation products of CS under different conditions.And from the crystal structure perspective,the process of CS carbonation and the mechanism of synthesizing different poly-morphs of calcium carbonate were analyzed Results Under room temperature conditions,CS is mainly car-bonated to form calcite,and different aeration rates only affect the initial stage of the reaction.The optimal aeration rate obtained from experiments under these conditions is 4 L/min.Under 80 ℃ conditions,the product transforms into aragonite calcium carbonate whiskers.Compared to the aragonite-type calcium car-bonate structure,the calcite-type calcium carbonate structure is more stable and easily generated at room temperature.While aragonite is metastable,requiring magnesium chloride control and high temperature con-ditions.The differences in crystal structure and space group are the fundamental reasons for the carbonation production of calcite and aragonite under different reaction conditions.Conclusions In this study,CS was carbonated at room temperature to absorb CO2 while simultaneously generating calcite-type calcium carbon-ate.By varying the reaction temperature and employing polymorph controller,it was possible to adjust the carbonation product to form aragonite-type calcium carbonate.These findings provide guidance for the high-value utilization of CS,reducing environmental pollution and the sequestration of CO2.