This year’s winter repairs in the WESTKALK Vereinigte Warsteiner Kalksteinindustrie GmbH & Co. KG in Warstein and Kallenhardt, both Germany, were concluded with the replacement of a more than 820 m long rubber conveyor belt in the Kallenhardt works (Figure 1). The replacement had become necessary after seven years because the belt hat worn severely over the years. During this time, the belt had also been mended at several points already. The repair project cost over 70,000 €. WESTKALK regularly uses the winter time for maintenance and repair work because the plants in the processing industry, such as cement works, are also regularly serviced during this time and many construction sites come to a standstill because of the weather.
It took experts from a specialist company two days to mount the 1,000 mm wide conveyor belt from a total of four rolls onto the conveyor system. Each of the three 250 m rolls weighed about 7 t. Even the smaller roll weighed over 3.5 t. Particular care needed to be taken in joining the sections, which was done by hot vulcanisation with a vulcanising press. This works in a similar way to patching a bicycle inner tube, but at temperatures of approximately 150 °C. The extremely tear-resistant, robust belt has a fabric lining made of polyamide and polyester. Around it there are cover plates, which are 8 mm thick on the material carrying side. The underside is coated with 3 mm of rubber. The employees were specially trained for the installation work using the wheel loader.
Conveyor belts are the main means of transport in the processing plants of the stone industry. At the Kallenhardt and Warstein works of WESTKALK there is a large number of rubber conveyor belts of varying lengths and widths; some only 1 m long, others 20 m or more. By far the longest conveyor section is found in the plant at Kallenhardt. It is a double-level belt system that spans the section between the primary crusher and the storage silo, or the pile of material to be washed, with two conveyor belts arranged one above the other. The top conveyor belt is enclosed in order to ensure that the crushed limestone reaches the silo dry and without dust being blown around. There is a particular risk of wear on the conveyor systems if large, sharp-edged stones or metal parts slit open the belt lengthwise.
Incidentally, the old belt parts are not waste; they are reused. Old conveyor belts, e. g., are very popular with farmers and are used for a variety of purposes. (WESTKALK/Si.)