Abstract: To solve the problems caused by pulp preprocessor used together with XJM-S series flotation machine in the process of enlarging equipment and modifying old plant,mineralizing device with the function of pulp preprocessor is developed,and then its amplification criterion is given by analysis of fluid mechanics characteristic and main structure parameters affecting operation. The study shows that cross-sectional area ratio m is the main structure parameters affecting operation of mineralizing device; flotation effect of coal slime is better when value of m ranges between 4 and 6. The application shows that XIM-KS series flotation machine with mineralizing device is preferred to the XJM-S series flotation machine with pulp preprocessor.