Panorama Press Releases

Press Releases

Difficult but achievable - A bucket-elevator rebuild at Märker Zement

AUMUND Group was contracted by Märker Zement when it needed a bucket-elevator to be converted at its plant in Harburg, Lower Saxony, Germany. Despite the difficult location of the elevator within the plant, the rebuild was completed in record time.

 

Record delivery time


Despite difficult space constraints at Märker Zement’s Harburg plant, the rebuild was completed in record time and after only 10 working days the bucket-elevator
on the No.8 cement mill at Märker Zement in Harburg was recommissioned. During the rebuild, the location of the bucket-elevator in the centre of the mill building proved to be a great hindrance. As the roof of the building could not be opened,
access from above was not possible. For this reason all necessary parts for the central chain bucket-elevator (type BW-Z) were raised almost 27m into the air through the chimney. This also applied to the bucket-elevator head. It was prefabricated in individual sections and was first mounted on the working platform and then welded together. “Despite numerous bucket-elevator rebuilds it was still not an everyday event for us,” said Peter Müller who, as AUMUND's project leader, was in charge of the conversion. “We could largely reuse the existing bucket-elevator head.” According to Märker project leader, Franz Ferber, the rebuild of the central discharge bucket-elevator had been necessary because
spare parts were no longer available for it. “In addition we were interested in more flexibility. If the capacity of mill No.8 should be increased the bucket-elevator must be in a position to accommodate the increasing conveying volumes. This
is now the case.”

 

Rebuild versus newbuild

The question of economy also played a role,because rebuilds are often an interesting alternative to a newbuild. In this way the existing steel structure can largely be reused. That reduces material costs by 30% compared to a newbuild.
The assembly is also less complex, which means that downtime is significantly shorter in most cases. “These are very often good arguments for a
rebuild,” added Müller. As is often the case with older installations there were no technical plans for the old elevator. Therefore all relevant data and measurements were recorded with the help of electronic data capture, photos and sketches in order to be able to create a design drawing on this basis.

 

New specification and benefits

After the rebuild the bucket-elevator has an axis distance of 26.8m. It is equipped
with 151 buckets all of which are 450mm wide and have an radius of 280mm. At
a filling level of 73% and a velocity of 1.4m/s, a conveying capacity of 200t/hr
is achieved, resulting in a potential capacity increase of 38% compared to the
old bucket-elevator. Electrical consumption of the bucket-elevator was lowered by around 5%. The main reason for this is the conversion from scooping to direct filling of the buckets. In addition the inlet was raised somewhat and its angle changed to 45°. The desirable and pleasing side effect is significantly lower maintenance costs. The central chain concept and direct loading reduce the wear on the buckets, on the circulating parts and on the drive. Ferber is pleased with the new installation, saying, “The bucket-elevator runs very reliably. We have the necessary conveying capacity, very good availability alongside lower energy and maintenance costs.”