Ethernet and Profibus in a potassium mine

System Integration & Control Systems Design

Systems - process or technology specific suppliers

May 2003 System Integration & Control Systems Design

It is believed that the potassium deposits in Germany were formed more than 200 million years ago. Today, these deposits, lying deep under the surface, provide an important natural product: mineral salt. Mineral fertilisers for agriculture and raw materials for the chemical industry are produced from this mineral salt.

Kali and Salz extract the mineral salt from the huge (240 km²) Hattorf/Phillippsthal potassium mine, from depths ranging 700 m-1000 m below the surface. Massive underground vehicles move the raw mineral salt to the conveyor belts, which total more than 100 km in length. The mineral salt is delivered by these conveyor belts to the shaft where, in around a minute, it is carried to the surface for further processing.

The visual display of production processes is imperative today. Parameters relevant for safety are measured and monitored, for instance the carbon dioxide content of the air in the shaft and the temperature. The potassium oxide content of the product on the conveyors (and therefore the amount mined) is also measured continuously. At a capacity of 75 000 metric tons per day, there can be no malfunctions. All process signals are measured by distributed I/O devices and sent to the PLC using Profibus; here the data is collected in so-called head stations. The Profibus data is transmitted to the individual PLCs using either copper or fibre-optic cable, depending on the location. The PLCs in turn supply the data to an In-Touch display system in the control rooms and central measuring stations via an industrial Ethernet network.

Kali and Salz use Hirschmann components in its potassium plants, and the automation networks were planned and built by Siemens.

Project parameters

Due to the geographical position of the mining areas within the mine and the physical size of the mine, a star shape network topology with single mode optical fibres for Ethernet was initially set up. From this basis, a redundant optical fibre ring (HIPER-Ring) was produced by means of extensions. As the extraction of the mineral salt underground is a process that is continuous in the true sense of the word, the machines and plant must be physically moved along from time to time. For this reason the controllers and distribution with the rail switches are installed such that they can be moved.

Hirschmann equipment was selected for its operating safety, HIPER-Ring redundancy, suitability for industrial use, reliability, expandability, cascadability, with straightforward commissioning that facilitated an installation that can be moved, featuring matched components.

For more information contact IAC, 012 664 4481, www.iaconline.co.za

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System Integration & Control Systems Design

Ethernet and Profibus in a potassium mine

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