Original operation
The plant operated two cement mill systems producing blended cement. CM1 produced approximately 65 t/h; CM2 produced approximately 20 t/h. CM1 was a ball mill in closed circuit with a high-efficiency classifier and a pregrinding system. CM2 was an open-circuit ball mill.
The reported Blaine fineness values were 4,700 for CM1 and 4,100 for CM2. To meet cement strength requirements, the respective feed mixtures contained 68% and 79% clinker. The balance consisted of additives such as gypsum, limestone, and pozzolan.
Options considered
- Add a high-efficiency classifier to operate CM2 in closed circuit.
- Add a pregrinder for CM2 in addition to the classifier in Option 1.
- Modify the CM1 pregrinder to feed both mills, together with Option 1.
- Direct the CM1 pregrinder product to CM2 and feed the CM2 product to the CM1 classifier.
Selected solution
The selected solution was to feed the CM2 product to the existing high-efficiency classifier serving CM1. A screw conveyor transferred the CM2 discharge to the CM1 bucket elevator feeding the classifier. The classifier and auxiliary equipment were checked and found suitable for the revised operation.
This arrangement allowed the CM2 feed mixture to match the CM1 mixture, reducing the cost of the cement feed blend. The reported payback for this historical project was less than two weeks; this result was specific to the project’s costs and operating conditions.