The cement plant at Mfamosing, located thirty kilometres north-east of Calabar, capital of Cross River State, Nigeria, has been fully operational since February 2009, and is equipped with the latest technology.
With a capacity of 2.5 million tonnes of cement per year, the UNICEM plant should now be extended by LOESCHE technology.
The customer ordered two vertical roller mills. One of type LM 60.4 for the grinding of cement raw material with a product rate of 500t/h.
Cement clinker will be ground with the brand-new highlight, the LOESCHE mill type LM 70.4+4 CS. This mill is designed for a capacity of more than 370t/h, to a fineness of 4,700 Blaine. In combination with this enormous capacity, a new drive system for an operation power up to 8,800kW is necessary. In a close cooperation between RENK AG Augsburg and LOESCHE GmbH Düsseldorf this development was established. Input from the enduser LafargeHolcim was taken into consideration.
The innovative result is the COPE (Compact Planetary Electrical) drive. The new concept is designed for mill drive powers ranging from 4,000kW to 15,000kW. The fast-running and error-prone first stage gear of conventional gearboxes becomes obsolete. The new concept is equipped with an active redundancy.
The innovative COPE gearbox is equipped with eight individual drive units, which are designed for a capacity of 8,800kW. The decisive customer benefit lies in the fact that in case of the unlikely event of a drive unit failure, the guaranteed mill capacity can be 100% achieved and a loss in production will not occur.
Some more advantages:
- Equal size as standard drive units for vertical roller mills and thus exchange of existing, conventional gearboxes eminently suitable.
- First use of a eight drive units for a VRM gearbox
- First time multiple drive in VRM to operate with or without VFD (variable frequency drive)
- Easy removal of individual drive units to minimize down times (approximately 2h)
- Extremely compact design with motors directly attached to gearbox housing
The utmost important aspect of this development is the fact that long stand stills of a mill (for several months) due to the repair of any of the conventional gearboxes will be a matter of the past. Implementing the COPE drive requires the standard foundation only. The replacement of one of the eight small drive units will be easily conducted as they are easily accessible and easy to install.
The delivery started in October 2015. First production of cement was in September 2016. The guaranteed values could be achieved after only 40 operational hours.