Mixing technology in ready-mixed concrete plants: From disassembly to the first delivery in just three weeks
After more than 30 years, the mixing and weighing equipment at the Kressbronn ready-mix concrete plant had reached the end of its technically and economically useful life. Comprehensive modernization was called for. Previously, all seven plants operated by the group in the Lake Constance region were equipped with pan mixers. The group of companies in which the Kressbronn concrete plant is integrated has now installed a BHS twin-shaft batch mixer for the first time during modernization of the concrete plant.
The principal criteria applied for selection of the mixing system were excellent homogeneity of the mixtures, short mixing cycles and a future-proof design, along with favorable operating costs, low wear and reliable service. Assurance of the completion and commissioning deadline was another crucial factor besides the investment and operating costs. The outcome of an intensive selection process was that the BHS mixer was the best choice for the application at the Kressbronn ready-mix concrete plant. The positive experience with this mixing system reported by comparable plants also played a key part in endorsing the decision in favor of the BHS twin-shaft batch mixer.
The central element of the new plant is a DKXS 2.5 twin-shaft batch mixer with a rated output of up to 2.5 m³ of compacted concrete per batch. It replaces the two pan mixers, which had each produced 1.0 m³ per batch.
Unlike pan or planetary mixers, which mix in two dimensions only, BHS twin-shaft mixers create a three-dimensional motion pattern of the entire mixture. There is also an intense exchange of materials in the turbulent zone where the two mixing cycles overlap. They additionally support high variability in production, allowing highly uniform mixtures to be produced even in small batches. Moreover, they achieve low specific energy consumption thanks to optimal conversion of the energy input into intensive relative motion of the entire mixture.
On account of their higher filling level, BHS twin-shaft mixers are much more compact than other mixing systems, usually allowing larger mixer types to be installed in the available space in case of plant modifications.
Individual solution with modular system
Drawing on the modular system of the DKX series, which offers a host of configuration options based on a broad selection of drives, mixing tools, discharge openings, wear liners, sensors and comprehensive accessories, BHS configured a mixer for the Kressbronn plant that is specifically tailored to the individual requirements.
As part of the modernization project, the entire weighing, metering and control system was adapted to the latest state of the art and safety regulations, and a new mixing and weighing platform was installed.
On completion of the comprehensive overhaul of the control system as the final step in the modernization, the new plant produced its first concrete on Monday, February 20.
Initial experience
In practical operation, the new plant mixes up to 35 batches per hour, achieving an output of almost 90 m³ in this period. Thanks to the better mixing effect of the BHS mixer, the mixing and metering times for the individual formulas are currently being further optimized.
Truck mixers with a capacity of 7.5 m³ are now loaded with just three batches. The modernization has virtually doubled the output of the mixing plant owing to the short mixing cycles, the balanced relationship between the batch size and the truck mixer volume, and the associated reduction in the number of batches per vehicle.
The mixer can also produce homogeneous partial batches of less than ten percent of the mixer capacity. Almost even more important here is that these quantities are also discharged in a short time due to the spiral-blade mixing mechanism – a key aspect particularly for ready-mix concrete plants in rural areas, where small and extra-small volumes are an everyday occurrence.
About BHS-Sonthofen
BHS-Sonthofen GmbH offers innovative and efficient mechanical process solutions for mixing, crushing, recycling and filtration applications.
Since development of the first twin-shaft batch mixer in 1888, the company has demonstrated its innovative strength time and again with numerous new products. DKX twin-shaft batch mixers are regarded as the global benchmark where demanding mixing applications in the concrete industry are concerned.
For more information, visit www.bhs-sonthofen.de.
Kontakt
BHS-Sonthofen GmbH
Roland Schmid
An der Eisenschmelze 47
D-87527 Sonthofen, Germany
+49 8321 6099-231
press@bhs-sonthofen.de
http://www.bhs-sonthofen.de
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Regina Reinhardt
Süsterfeldstrasse 83
52072 Aachen, Germany
+49.241.89468-24
reinhardt@vip-kommunikation.de
http://www.vip-kommunikation.de