European Salt Company GmbH & Co. KG –, a company of the K+S group registered in Hannover, commissioned H+H to carry out a comprehensive retrofit of the dispatch internal logistics at its Bernburg plant. In the transport equipment installed in the first half of the 1990s wear-affected and moving parts were changed. On the basis of prior experience some components were replaced with variants of improved design. The work was carried out without interfering with on-going operations.
esco, which has around 20 branches all over Europe, is part of the K+S group, one of the largest salt producers worldwide. The Bernburg mine has existed for more than 100 years and is located in a region with a long tradition of salt extraction. Nowadays the plant’s product range extends from de-icing and industrial salts, through edible salts, to salts for commercial use.
The miners extract a rock salt which, because of its pure-white colour and coarse crystalline structure, is called crystal salt. On average its purity level is around 99 percent sodium chloride (NaCl), while the very best batches even contain 99.8 percent of NaCl. After a first processing step underground the coarsely crushed salt undergoes further milling and sieving stages above ground. These produce salts of various grades and with varying grain structures, with which the needs of customers can be met quickly and flexibly.
The goods, packed as specified by the customer, are stored in a high-bay warehouse on Europallets. The automatic transport system takes up the consigned pallets from the production lines and transports them to the storage lanes in the high-bay warehouse. The items to be retrieved are collected by storage and retrieval machines in the high-bay warehouse and transferred to chain conveyors. These transport them to a double transverse distribution trolley, which then distributes the pallets among the retrieval lanes. From there, the goods are delivered by fork-lifts to the truck loading ramps.
The transport equipment was installed in 1995 with H+H Herrmann + Hieber as general contractor. For its part, H+H entrusted the mechanical equipment to a subcontractor, whereas the control system was supplied by H+H itself.
The particular problems to be faced by this pallet transport system are on the one hand the relatively large weights to be carried – the packs weigh over 1,000 kilograms – and furthermore, the aggressive, salty environment. Owing to its location within a salt processing operation, the transport equipment has to be particularly corrosion resistant.
As a result of these difficult operating conditions, now after almost 20 years of operation a renovation of the mechanical components had become necessary. The control system is still fully functional. The contract for the first partial renovation was again awarded to H+H, whose task it was to carry out thorough maintenance of selected elements of the conveyor technology in the area of retrieval from the high-bay warehouse. The key elements were the dismantling and re-supply of a double transverse distribution trolley, including a rail system, and the fundamental renovation of a total of six chain conveyors in the transfer area to the distribution trolley.
In operation the originally installed slide bearings in particular were found to be particularly prone to failure. For that reason, as part of the renovation of the deflector units the slide bearings were replaced by deflectors with roller bearings. The newly designed deflector roll is a special combination of a ball bearing and a chain wheel, which is designed to ensure long-lasting and stable transport operation.
One of the customer’s main requirements was that on-going operations should not in any way be impeded by the renovation measures. Accordingly, after careful planning and preparation all the work was carried out over just one weekend. To achieve that in such a narrow time-slot, a total of eight assembly workers were on site.