A new chemical pre-desilication process of kaolinite in diasporic bauxite in alkali solution at atmospheric pressure was proposed.The dissolution kinetics and mechanism were studied by chemical analysis,XRD and SEM.Th...A new chemical pre-desilication process of kaolinite in diasporic bauxite in alkali solution at atmospheric pressure was proposed.The dissolution kinetics and mechanism were studied by chemical analysis,XRD and SEM.The kinetic results of dissolution process show that the kaolinite is symbiotic with diaspore but without cladding.The dissolution ratio of kaolinite is close to 100%at 100℃for 90 min.The dissolution kinetic equation is 1-(1-α)^1/3=7.88×10^6 exp[-64434/(RT)]t.With the low L/S(L/S=10:1),the dissolution ratio of kaolinite decreases to 55%.This is due to the formation of lamellar hydroxyl-sodalite(OH-SOD)which is deposited on the surface of kaolinite and hinders the further dissolution of kaolinite.Under the optimum conditions,the A/S(mass ratio of Al2 O3 to SiO2)of dissolved residues is increased to 8.55,while the A/S of the bauxite is only 4.97.展开更多
基金Project(2018YFC1901903) supported by the National Key Research and Development Program of ChinaProjects(51774079,51674075) supported by the National Natural Science Foundation of ChinaProject(N182508026) supported by the Fundamental Research Funds for the Central Universities,China
文摘A new chemical pre-desilication process of kaolinite in diasporic bauxite in alkali solution at atmospheric pressure was proposed.The dissolution kinetics and mechanism were studied by chemical analysis,XRD and SEM.The kinetic results of dissolution process show that the kaolinite is symbiotic with diaspore but without cladding.The dissolution ratio of kaolinite is close to 100%at 100℃for 90 min.The dissolution kinetic equation is 1-(1-α)^1/3=7.88×10^6 exp[-64434/(RT)]t.With the low L/S(L/S=10:1),the dissolution ratio of kaolinite decreases to 55%.This is due to the formation of lamellar hydroxyl-sodalite(OH-SOD)which is deposited on the surface of kaolinite and hinders the further dissolution of kaolinite.Under the optimum conditions,the A/S(mass ratio of Al2 O3 to SiO2)of dissolved residues is increased to 8.55,while the A/S of the bauxite is only 4.97.
