1976 Volume 25 Issue 274 Pages 675-678
To investigate ball mill grinding from the kinetic point of view, the effect of hardness of samples and feed weight on grinding rate constants has been studied.
The samples used were silica glass, borosilicate glass, soda glass, quartz, feldspar, limestone, marble, gypsum and talc. The pebble mill consisted of a 12.8cm-diameter by 13.2cm-long cylinder and the grinding medium was 40 balls, each of which had a diameter of 3cm and their total weight was 1180g. The tests were done at the speed of 88.1% of critical one. The size analysis was done by 21/2 series of Tyler standard sieves in Rotap machine. The experiments were performed on -14+20 mesh feed size to obtain the grinding rate constants. In the previous paper, we had derived the following equation.
where K1 is the first order decreasing rate constant of feed size, HV dimensionless Vickers hardness and W1 dimensionless feed weight. On the basis of this concept, further investigation was made on the rate constant of under size increasing Kx of zero order kinetics, and the following results were obtained.
(1) The correlation of particle size ratio x/x0, dimensionless feed weight W0, HV and Kx can be shown by Eq. (II).
(2) To obtain Kx from K1, the Eq. (III) can be used.