DEVELOPMENT OF A NEW REACTOR FOR COMBINED COMMINUTION AND CHEMICAL-REACTION

The combining of the two process steps comminution and chemical reacti on is realized in a newly developed apparatus, the so-called reaction- mill. It is an up to 450 degrees C heatable vibration-mill, that is re sistant to pressures up to 2 MPa and that has a gas inlet and outlet f or running heterogeneous chemical reactions during the process of comm inution. The possible accelerations of the vibration-mill exceed up to 65 g and relative amplitudes of maximum 0.14 are adjustable. The adva ntage of the combination of the two process steps is the utilization o f the effects of comminution exceeding the changes in the dispersity o f the solid. The examined heterogeneous non-catalytic gas-solid reacti on is the conversion of metallurgical grade (MG) silicon with gaseous hydrogen chloride to give trichlorosilane and silicontetrachloride. Th e examinations of the combined hydrochlorination and comminution have shown, that the induction periods in the starting phase of the reactio n, carried out singularly, can be reduced to a minimum. Furthermore it could be noticed, that the lower temperature limit, which is necessar y to start the reaction, could be lowered from 300 degrees C to 100 de grees C and that the selectivity of the reaction products is influence d by the mechanical energy. On one hand the effects are explained by t he changes in the dispersity of the solid during comminution and on th e other hand by a mechanical activation of the MG silicon.