Kinetics of Hydrochloric Acid Leaching Al3+ from Montmorillonites
The components of purified samples were examined by means of X ray diffraction (XRD) and FTIR. XRD was performed on unorientated samples with an Ultima IV diffractometer, operating at 40 kV and 40mA, using Ni-filtered CuK α radiation, at a scanning speed of 8°2θ/min. FT-IR spectra were obtained using a Nicolet 380 FTIR Spectrometer. 3 mg of each sample previously dried at 110°C for 3 hours were mixed with 160 mg of KBr and pressed on disks. The particle-size distribution of the purified sample was determined by Bettersize BT-9300Z laser particle analyzer. A complete chemical analysis of the purified samples was performed by use of China's Nation Standard GB/T 16399-1996 and GB/T 14506.28-2010. Select Al3+ as the structure cations leaching objective to learn the cationic leaching kinetics on acid leaching montmorillonite. Acid leaching were carried out in a 250 mL three-neck flask which was soaked in a constant temperature oil bath to heat. A mechanical stirring rod, a thermometer and a condensing tube were inserted in the flask through the three necks, respectively. For each run, the solution was freshly mixed by 100 mL distilled water and 20 mL 37% analytical grade hydrochloric acid in the three-neck flask and stirred at a fixed rate of 300 r/min. When the temperature was reached, put 4 g sample into the flask through one neck and start to clock. The liquid-solid mixture was heated at 47, 67, 87 and 97℃ respectively, for different period time between 1 hour and 45 hour. After the designed leaching time, the mixtures were centrifuged immediately. Precipitation was washed by deionized water repeatedly until without Cl- tested by AgNO3 liquid drop. After drying, grinding solid product to -200 mesh (-75μm). The constant volume of filtrate and lotion were used to determine the leaching amount of Al3+ from montmorillonite by China's mechanical industry Standard B/T9225 - 1999. According to the total chemical analysis of Al3+ and the content of Al3+ in the leaching solution, the leaching ratio of Al3+ XB at different time was calculated, and a variety of dynamic model of liquid-solid reaction was fitted. There are two type models commonly used in literature for liquid-solid reaction: Shrinking-Core Model (SCM), also called interfacial reaction models, and Progressive-Conversion Model (PCM), also called capacity model. All fitting figures are drawn with ORIGIN software.