Study On Crystal Regulation Of Calcium Carbonate Mineral

As one of the most important inorganic mineral materials,calcium carbonate's crystal shape and surface properties determine its properties.In order to explore the factors of crystal type and surface properties of calcium carbonate,two crystal types,calcite and aragonite,were prepared by chemical precipitation method,and the crystal type and surface characteristics of calcium carbonate were controlled by adding carboxylic acids of different chain lengths.Calcium carbonate was prepared from calcium chloride and sodium carbonate.The effects of different reaction temperature,concentration and molar ratio of Ca²⁺to CO₃^2-on the crystal morphology of calcium carbonate were studied.The synthesized calcium carbonate was characterized by XRD,FESEM and FT-IR.When the reaction temperature is 75?,the reaction concentration of calcium chloride and sodium carbonate is 4mol/L,the molar ratio of Ca²⁺to CO₃^2-is 2:1,the stirring rate is 500 r/min,the drop acceleration rate of adding calcium chloride solution to sodium carbonate solution is 1ml/min,and the reaction time is 1h,the prepared calcite calcium carbonate has a high purity.When the reaction temperature is 60?,the concentration of calcium chloride and sodium carbonate is 1.25 mol/L and 1.375 mol/L respectively,the molar ratio of Ca²⁺to CO₃^2-is 1:1.1,the agitation rate is 500 r/min,calcium chloride is dropped into the sodium carbonate solution at a rate of 1ml/min,and the reaction time is 10 min,the pellet aragonite calcium carbonate is prepared with high purity.The content is close to 100%.Calcium carbonate was prepared from calcium nitrate,sodium carbonate,calcium chloride and sodium carbonate.The crystal structure and surface properties of calcium carbonate were regulated by adding tetradecanoic acid and docosanoic acid.The effects of the addition of tetradecanoic acid and docosanoic acid on the crystal structure of calcium carbonate were studied by means of SEM,XRD,FT-IR,TG and XPS.The results show that after the addition of tetracanoic acid,the crystal structure of calcium carbonate changes from spherical aragonite to calcite,and the morphology changes from spherical to irregular cubic.From hydrophilic to hydrophobic,the surface hydrophobic,calcium carbonate agglomeration degree decreased significantly.After the addition of succinic acid,the crystal structure of calcium carbonate changed from calcite to spherical aragonite,and the morphology changed from irregular cubic shape to spherical shape.From hydrophilic to hydrophobic,the surface hydrophobic,calcium carbonate agglomeration degree decreased significantly.