Siemens has been commissioned to modernize the drive systems for four mills at the Collahuasi copper mine in northern Chile. The company will supply complete state-of-the-art drive systems comprising new motors and Flender couplings with torque limiting shear pin as well as new Sinamics SL150 cycloconverters with thyristor stacks. The new drive systems will give a huge boost to the reliability and consequently also the throughput of the mills, according to Siemens. The terms of the deal were not disclosed but the contract would be valued in the double-digit million dollar range.

The modernization project includes two 8-megawatt (MW) semiautogenous (SAG) mills and two 1.7-MW ball mills with dual pinion drives. The new drive systems are replacing the existing synchronous motors and direct converters for the SAG mills and the drive systems of the ball mills, which were installed by a different manufacturer. The standardized system design now offers all the benefits of controllable drives also for the ball mills.

When implementing this project, to prevent costly standstill periods and also to minimize risk, it was vital for the new motors to fit on the foundations constructed for their predecessors. A decision was also taken to replace the entire mill automation system by modern technology rather than adapting the hardware and software.

The direct converter and the new automation systems were installed in ready-assembled new “E-Houses,” which were completely developed, produced and pre-tested in the plant to be subsequently connected and commissioned on site. The location of the mine at an altitude of more than 4,200 m above sea level meant that particular care had to be taken with the electrical and thermal dimensioning of components.