GEBR. PFEIFFER to supply the world’s largest vertical roller mill for cement

GEBR. PFEIFFER SE will supply the world’s largest vertical roller mill for Holcim (Brasil) S.A. The MVR 6700 C-6 will be producing up to 450 t/h of cement. It will be grinding various blended cement qualities with clinker proportions of up to 90 % and slag proportions of up to 65 % to product fineness degrees of 4000-4800 cm²/g acc. to Blaine. A MultiDrive® with 6 single drives, each of 1920 kW, will be used to drive this mill. This innovative drive concept will have an available total drive power of 11,500 kW. This amount of power cannot be implemented with conventional drive systems for vertical roller mills. The individual drives will be synchronized by frequency converters which will also allow the speed to be adapted to the various product qualities.

The Spanish EPC contractor CEMENGAL was awarded the contract to supply a complete cement grinding plant to increase the capacity of Holcim’s Barroso works located in the Brazilian state of Minas Gerais, for which in addition to the complete vertical roller mill GEBR. PFEIFFER SE will supply a hot gas generator, which is intended to provide the heat when materials of high moisture content are ground and/or clinker cooler exhaust gases are not available.

During the technical development of the MVR mill GEBR. PFEIFFER SE placed special emphasis on plant availability and ease of maintenance. As a result, the new mill concept allows grinding rollers to be swung out from the mill individually for maintenance works, for example to replace the wear parts, without the need to interrupt operation for a prolonged time. After one roller has been swung out, the mill can continue to operate. In the case of the mill for Holcim (Brasil) S.A., this means that the capacity achieved will still be significantly more than 80 % of the nominal grinding capacity. Comparatively, the 2-mill concept, an alternative for this capacity, would involve substantially higher total investment costs and the outage of one grinding roller would cause the grinding capacity to reduce by half due to the lack of active redundancy.

Similarly to the grinding rollers, the MultiDrive® is also actively redundant where each of the 6 drive modules installed for this application can be disengaged.

Many years’ operating experience of vertical mill operators has been incorporated into the overall MVR concept with MultiDrive®. At this point special mention is to be given to HOLCIM who not only ordered the first MultiDrive® for a vertical roller mill in 2008 but also actively accompanied the technical detailed implementation through Holcim Group Support, Switzerland.

The mill concept MVR with MultiDrive® is a revolutionary advance in the area of vertical mill technology thanks to the active redundancy of the rollers and the drive modules. Active redundancy allows even the largest units to obtain levels of availability that have so far been unachieved. This innovation enables, for the first time ever, large cement facilities to be designed with the one-mill concept for both raw meal and cement grinding.

The mill planned to be commissioned at Holcim (Brasil) S.A. in 2013 will mark another milestone in Gebr. Pfeiffer’s 150-year history.