一水硬铝石型铝土矿中高岭石的常压碱溶动力学与溶出脱除机理（英文）

Dissolution kinetics and removal mechanism of kaolinite in diasporic bauxite in alkali solution at atmospheric pressure

提出一种一水硬铝石型铝土矿中高岭石的常压化学预脱硅新工艺。通过化学分析、XRD和SEM对溶出过程动力学及溶出机理进行研究。溶出动力学结果表明,高岭石与一水硬铝石虽嵌布共生,但并无包覆现象。因此,在100℃下,高岭石溶出90 min的溶出率可接近100%。溶出动力学方程为1-(1-α)^1/3=7.88×10^6exp[-64434/(RT)]t。低液固比(L/S=10:1)条件下,高岭石的溶出率降低到55%。这是由于形成层状羟基方钠石(OH-SOD),并沉淀在高岭石的表面,阻碍高岭石进一步被溶出。在最优条件下,可以将溶出渣的铝硅比提高到8.55,而原矿中铝硅比仅为4.97。

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.