Roles of the Net in the Column on Tower Mill KD - 3

Abstract

In fine grinding practice the efficiency of comminution depends largely on the behavior of freshly formed fine particles. In the case of a dry tower mill, fine particles are directly removed due to circulating air flow generated inside the mill, and immediately particles are classified in the classifying column. Especially in the Tower Mill KD - 3, in order to achieve a high classifying efficiency it is essential to reduce the air turbulence in the classifying column. Although it had been provided with the series of nets in the column of the KD - 3, the efficiency of nets was not clarified. In this study, by investigating the roles of nets, it was found that the air turbulence reduced and the classifying efficiency was improved by setting with the nets in the column. The results of these investigations using 4 type columns (CLA 0, CLA 1, CLA 2 and CLA 3) can be summarized as follows: (1) The weights of products in the cyclone increase using the no-nets classifying column (CLA 0), conversely the weights of products in the classifying column decrease. (2) The series of nets in the classifying column have no influence on the electric consumption of the blower motor and stirring motor. (3) The relationship between maximum and 50 % particle diameters was proportionally and by using the columns provided with nets (CLA 1, CLA 2 and CLA 3), the overflow products and underflow products were classified by the high classifying efficiency. (4) The maximum particle diameters of products were indicated by the corrected curve which is estimated by the assumption of Stoke's law. (5) The air flow rate of duct and the pressure drops of the column were approximately quadratic curve. And the maximum particle diameters of products in the cyclone were proportional to the pressure drops of the classifying column.