Influence of vibration grinding and calcination on the physico-chemical properties of Egyptian kaolinite

The effects of vibratory grinding and calcination on the structure and reac tivity of Kalabsha kaolinite were studied by means of XRD, IR, DTA and surf ace area determination. Leaching experiments on ground and calcined samples were carried out using 20% HCl for aluminum extraction. At the early stage s of grinding, partial destruction of stacked kaolinite layers occurred. Th ese changes were associated with an increase in surface area due to formati on of fine grains with numerous boundaries. Further grinding, as well as ca lcination, led to deterioration of the kaolinite structure. A significant i ncrease of surface area was observed, starting from 18 m(2)/g for the origi nal sample to a maximum of 42 m(2)/g after 120 minutes of grinding and 30 m (2)/g after calcination at 300 degrees C. The extraction of aluminum after 30 minutes leaching time was about 97% for kaolinite ground for 240 minutes , and about 93% for kaolinite calcined at 550 degrees C.