Optimised cement mill performance

The following graph shows the improved performance achieved by optimising cement production on an open circuit mill. Output of Ordinary Portland Cement has been increased from an average of 50 tph to 65 tph, whilst the +45µm residue has also decreased from 18% to 14%, resulting in a 2 MPa improvement in 28 day strength.

These benefits have been achieved by modifying the mill control methods, changing the ball charge distribution, stabilising clinker chemistry, fine tuning grinding aid use and optimising the existing water injection system.

The benefits of this work have been enhanced by complementary optimisation of the ball charge and installation of a customised water injection system on a smaller companion mill. These modifications have made it possible to dedicate the smaller mill to production of High Early Strength (HES) cement, which previously could only be produced on the larger mill.

Not only has this rationalisation resulted in virtual elimination of transitional product, cement performance and uniformity have also been improved across all cement types. HES in particular now has significantly better strength and setting time performance, largely due to the optimised water injection system, which has effectively eliminated the prehydration which had previously affected this product.