Dear MadSniggy,

The short answer is no. The optimum kiln feed residue depends on the mineralogy of the kiln feed. With a marl raw material of composition close to "cement rock" you might be OK with a 43% residue on a 90 micron sieve. But that would be very unusual. The more heterogenous the kiln feed and the higher the quartz content then the finer will the kiln feed need to be. So, no, there is no "golden rule" it depends on the raw materials you are using to make the kiln feed.

Dr Michael Clark