Continuous mixer from Lödige Maschinenbau in use at Hüttenwerke
High throughput, strong wear protection and particularly easy maintenance: In the coking plant of Hüttenwerke Krupp Mannesmann (HKM), a continuously operating intensive mixer from Lödige Maschinenbau performs exceptionally well.
Whether in fertilizer and animal feed production or in the processing of battery masses and fly ash, for example, heavy-duty applications place special demands on the process technology used. On the one hand, very high throughput rates are required in these areas of application. On the other hand, the machine must be able to process the sometimes highly abrasive materials without being damaged itself. And last but not least, the system components, which are subject to heavy wear in continuous operation, should be easy to maintain and clean.
Hüttenwerke Krupp Mannesmann (HKM) in Duisburg was also faced with this complex task. The coking plant there requires ground coal for the production of coke. To do this, the coal is first mixed intensively with a special wetting oil and various additives and residual materials (such as dust). The different materials are fed to the mixer from the corresponding storage bunkers in the correct ratio, mixed in the drum and later fed to the actual coke battery.
It’s all in the mix
Gebrüder Lödige Maschinenbau GmbH solved this task with a Ploughshare® mixer type KM 25000 DW. The continuous mixer with a drum volume of 25,000 liters is one of the largest continuously operating intensive mixers in the manufacturer’s 85-year history. Like all mixers from the Paderborn parent plant, this KM 25000 DW is a customized one-off production and is characterized by its extremely robust design. The construction time to delivery was eight months.
The mixer achieves the required high throughput rates thanks to a high and individually adapted mixer speed. The prerequisite for this is a special arrangement of the blades, the basic shape of which was patented by Lödige back in 1949. Like all horizontal Ploughshare® mixers, the KM 25000 DW intensive mixer also works according to the fluidized bed process introduced to industrial mixing technology by Lödige Maschinenbau, which ensures very good mixing: The plowshare blades rotate close to the wall in a horizontal, cylindrical drum. The circumferential speed and geometric shape of these mixing tools are designed to eject the mixing components from the material bed into the free mixing chamber and lift them off the drum wall, counteracting the centrifugal force.
The mechanical fluidized bed created in this way ensures very intensive mixing, even with high mix throughputs and short dwell times, while constantly capturing the entire quantity of mix. The mixing elements are shaped in such a way that continuous product transport is guaranteed.
Extensive wear protection
In order to meet the high demands of the coking plant, mixers for coal preparation are generally designed for high throughputs. The coal mixer for HKM is designed for a maximum output of 700 tons or 875 cubic meters per hour. For heavy-duty use in the coking plant, the mixing plant blades of the KM 25000 DW feature full-surface hard metal welding made of tungsten carbides.
As further wear protection, the mixer shaft is clad with a wear plate made of duplex steel (1.4462). As an additional measure, the inner area of the drum is completely lined with a strong aluminum oxide ceramic lining.
In order to achieve good accessibility for maintenance purposes - especially for replacing mixing tools and linings - the mixer is equipped with a large maintenance opening at the top of the drum.
