core sector communique

State-of-the-art robots with new spray nozzle technology for ThyssenKrupp Nirosta in Bochum

Electric arc furnaces need to be relined on a regular basis, but this is costly and time-consuming. Maintenance of the refractory material on the furnace walls is therefore of great importance. Following a two-month ramp-up period, a spraying robot fitted with state-of-the-art control technology will now take over this maintenance at the ThyssenKrupp Nirosta steel mill in Bochum. It is partially automated and therefore able to carry out complex refractory material maintenance without manual control. The newly developed spray nozzle technology permits a higher spraying speed and reduces the amount of hot repair material used through optimum wetting. At the same time, this technology ensures that the material is applied evenly at the desired thickness.

With the furnace running at full capacity, the refractory lining on its walls can usually withstand the temperatures of up to 1,650 degrees Celsius for two-and-a-half weeks. With the help of the spraying robot, the period before the refractory bricks need to be renewed can be doubled. The robot is controlled via a digital operator interface. It enables the operator to select precisely which wall areas are to be sprayed with the wetted magnesite, an unformed, sand-like refractory material. Binder components ensure that the material hardens on contact with the damaged areas and "seals" them. The maintenance operation takes between five and ten minutes and ensures the continued availability of melting capacity.

"We have also realized a further advantage in terms of servicing the new spraying robot," explains Helge Mees, head of the melting team at the Bochum steel mill. "ThyssenKrupp is looking to insourcing rather than outsourcing here." In the past, robot maintenance was carried out by the manufacturer, Minteq. As part of the new acquisition, the American company provided two ThyssenKrupp team technicians with comprehensive training on how to service and maintain the modern equipment. "This enables us to act flexibly and be independent of third parties," he continues.

The new spraying robot is therefore not only securing jobs but also making an important contribution to maintaining the production reliability of the electric arc furnace in Bochum and reducing consumption of refractory compounds.