The Siemens Drive Technologies Division has developed a new drive system and will supply six drive modules as part of a joint grinding project with Gebr Pfeiffer SE for Holcim Brazil.
The 450tph vertical cement mill will have a power rating of 11,500kW and be operated by the Brazilian arm of Holcim, which will commission the grinding plant as part of a project to expand its Barroso works in the state of Minas Gerais.
The modular and redundant drive system consists of six identical 1920kW drive modules that drive the grinding table of the cement mill. Siemens is also supplying all components of the drive train: gear unit, coupling and oil supply system, as well as electric motors and frequency converters.
The drive units are mounted on carriages, thus enabling them to be replaced quickly whenever maintenance is required and ensuring the fastest possible resumption of mill operation. The radial arrangement of the drive units around the grinding table bearings protects the drives against grinding forces.
The frequency converter allows variable speed adjustment and thus flexible adaptation of the milling process to suit the requirements of different input materials. This makes it possible to optimise, for example, throughput or energy efficiency. With this system configuration, even higher-output drive modules can be installed for an overall power rating of up to 16,500kW. Up till now, the mechanical engineering limit attainable by conventional plants was only 8000kW.
Siemens and Gebr. Pfeiffer SE have previously cooperated successfully on a number of different projects. The operating and project experience gained from vertical mills featuring integrated multi-drive systems in France, India and Australia could therefore be channeled into this new project.