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During the mining and subsequent storage of bauxite, a sedimentary rock for the production of aluminium oxide, a lot of dust is thrown up, which is a major challenge especially for the moving machine parts of the conveyor units. Partly for this reason, the Aluminum Oxid Stade GmbH (AOS), one of the major German alumina producers, decided to use energy chains of igus. For several years now, they have reliably supplied conveyor units and stockpiling equipment with energy, data and media.
Aluminium Oxid Stade GmbH (AOS) is one of the major alumina producers in Germany. It processes the raw material bauxite into aluminium oxide. The various types of bauxite are stored either in halls or in large open areas and fed into production by an impressive bucket-wheel stockpiling machine that can be seen from afar. In this process, the raw material is transported via an encapsulated conveyor belt system for intermediate storage before it is taken from there for processing. When a complete overhaul of the stockpiling equipment was due, those responsible decided not only to modernise the equipment itself, but also to renew the rail track and the energy supply system of the conveyor.
The particularly difficult environment (outdoor use, temperature fluctuations, humidity, dust) as well as the 366 m long track required a special solution. Since the motorised cable drums used previously required a great deal of maintenance and were always causing problems, Fabian Wilhelm, Head of Electrical Engineering at AOS, decided to use an energy chain system from igus for the first time in 2012.
Originally, the conveyor was supplied with energy and signals on its 366 m long track via a motor cable drum. Now a modern energy chain system from igus performs this task. Since the length of the travel results in push/pull forces that should not be underestimated, the project engineers recommended the use of a rol e-chain that does not slide in the guide trough but rolls over high-strength rollers with stainless steel ball bearings. Due to the unfavourable environmental conditions, a heavy duty roller chain of type 5050RHD is used. External radius stop-dogs prevent the conveyed material from getting stuck. In addition, the guide trough was equipped with an enclosure as a protection against rising and weather.
A floating moving end also ensures lateral tolerance compensation and an igus Push/Pull Detection System ensures the high availability that is essential in this application. The system continuously measures the push/pull forces that occur. If obstacles or blockages occur during the movement of the energy chain, they are detected by the Push/Pull Detection System and the system can then ensure an immediate stop of the conveyor. In this way, major damage, such as tearing off of cables, is avoided.
igus supplied the engineering and the e-chain system with all its components including the individual panel substructure. The complete installation on site in Stade was carried out by the igus installation service. Its employees installed the energy supply system, which is several hundred metres long, on the existing rail sleepers of the stockpiling equipment. The complete assembly with steel construction was carried out as planned in two sections and in a total of only twelve working days. The acceptance, handover to AOS and joint test drives took place on the agreed date, and since then the energy chain has been operating without any problems or irregularities.
"We attach the greatest importance to providing reliable deadlines and meeting them - even and especially when several different trades are working in parallel on construction sites like this one," Markus Böhm, Technical Sales Consultant at igus, points out. "Software developed in-house and tailored to our products creates the prerequisite for us to be able to plan precisely and offer our system assemblies at fixed prices. The fact that we also agree on individual guarantees for these services increases the safety and availability of the entire plant from the customer's perspective."
Another reason for AOS to award the contract to igus for the energy chain system including installation were further references in their own company: The igus installation service had already installed an e-chain system on a 140 m travel on the loop trolley of the AOS warehouse. An electronic push/pull force detection system is also used here.
Lastly, AOS relied on two more energy chain systems from igus, which travel in opposite directions in a common trough over a travel of 218 metres. They supply the two cranes that deliver the bauxite and then transport the produced alumina away again. Here, among others, medium-voltage motor cables of the series are routed, as well as fibre optic cables of the CFLG series.
