The plant has 2 cement mill systems that were producing blended cement.

One cement mill system (CM1) produced approximately 65 mt/h of cement and the second cement mill system (CM2) produced approximately 20 mt/h of cement.

CM1 is a ball mill in closed circuit with a high efficiency classifier and a pregrinding system. CM2 is an open circuit ball mill system.

The product from CM1 and CM2 are 4700 and 4100 Blaine respectively. To satisfy the strength requirements of the cement, the cement mill feeds for CM1 and CM2 included 68% and 79% clinker, respectively. The remainder of the mill feed mix include additives such as gypsum, limestone and pozzolan.

There were numerous options that were considered including:

Option 1. Install a high efficiency classifier to operate in closed circuit with CM2.

Option 2. Install a pregrinder system for CM2 in addition to the Option 1 modifications.

Option 3. Modify the CM1 pregrinder system so that it feeds to both CM1 and CM2 in addition to the Option 1 modifications.

Option 4. Modify the CM1 pregrinder system so that its product is fed to CM2 instead of CM1. In addition, modify the CM2 system so that its product is fed to the high efficiency classifier of CM1.

The selected solution was to feed the CM2 product to the high efficiency classifier of CM1.

This was accomplished by the installation of a screw conveyor that transported the discharge product from CM2 to the CM1 bucket elevator feeding the high efficiency classifier. The classifier and auxiliary equipment sizing were checked and were satisfactory for the new operation.

This option allows the client to change the cement mill feed mixture to CM2 to match those of CM1. This change lower the cost of cement mill feed mixture significantly.

The payback time for this project was less than 2 weeks!