We have cement mill with roll press and separator we are facing problem of low feed. W e have analysed the product and our finding are as below less than 3 micron - 12 per cent is in the final product less than 45 micron -17 per cent is in the separator return I think if we can separate this 17 per cent in the separator than our output will increase. Please suggest how should we increase the velocity across the seprator cage and also suggest how to eliminate less than 3 micron particals from the product.

The problem of the -45 micron material in the separator return is known as the "bypass" and is the proportion of fine material that reports to the returns even though it is ground fine enough. Adjustment of the separator speed is unlikely to dramatically improve this. My suggestion would be to conduct trials varying the air flow through the separator and assess which changes improve the performance. The super fine material in the finished product is most likely associated with the ball change grading in the finish grinding ball mill. Reducing the separator bypass may assist in reducing this. Otherwise you will have to tip and regrade the grinding media in the mill and conduct trials as you recharge the mill.

We operate one open circuit two chambers ball mill of size 4m dia X 13.5m long for Cement grinding. Capacity:100tpd drive motor: 2x1500 kW (twin drive) Power drawn: 2500 kW (more data on grinding media). >We are maintaining a blaines of 2700 to 2800. The cement is coarser having a residue of 10 per cent over 90 micron sieve and 30 per cent over 45 micron sieve. Increasing the blaines reduces output and increases the power consumption. How to achieve lesser residue keeping the same blaines.

There is no easy way to adjust the particle size distribution of an open circuit mill while maintaining the same Blaine. To do that you need a separator in closed circuit with the mill to send the oversize material for regrinding. You may have some success with grinding aids. Alternatively you could try for a more coarse media grading in the second chamber. However the results of doing that cannot be precisely predicted.