Leached chrysotile asbestos : characterization, leaching mechanism and use in the synthesis of zeolites

The work presented in this thesis is concerned with the transformation of the raw asbestos mineral to an intermediate material which is used for the synthesis of zeolites which are health safe and have wide applications in industry. First, a complete indexation of the X-ray diffraction pattern of chrysotile was proposed. This was followed by the use of techniques such as X-ray diffraction and bulk density measurements for the study of the mechanism of transformation of chrysotile to amorphous silica hemihydrate. In the second part, three types of zeolites were synthesized (Na-Y, Na-X and Na-A) using as starting material both silica gel (conventional method) and leached asbestos (new method). In a kinetic study of the crystallization of Na-A zeolite, it was found that leached asbestos is clearly more efficient than silica gel for the preparation of zeolite