We are using compressed air from Twin Lobe blowers for extracting fly ash from a 400t and 40t capacity hoppers equipped with open airslides at the bottom floor of the hopper. Please let us know whether the compressed air from the twin lobe blowers need to heated since at times flow problem occurs due to clogging.

If the fly ash is calcareous then there is the possibility of hydraulic reaction between the fly ash and any water present in the compressed air. My suggestion would be to install dryers on the compressed air supply.

Our plant has four cement mills (closed circuit with first generation separator) - we use about 20 per cent slag, the output is 100tph ,the dimension of every mill is 15.5 x 4.4, the liners in the first chamber are lifting and in second chamber classifier. Are there any ways to increase mill production? How about for a raw mill?

There are numerous ways to increase the production from your cement mills. In the short term use of grinding aids combined with optimisation of the ball charge and drafting would be the best method. Longer term (and at greater cost) you could upgrade the separators to third generation or install a roll press to pre-crush the clinker ahead of the mills. With regard to raw mills you can again use grinding aids or install pre-grinding equipment.