Tag Archives: twin-shaft

Science Research Technology

bauma premiere: Mixing high-abrasive material with minimum abrasion

Mixer for the sand-lime brick industry: New twin-shaft batch mixer with rubber provides low-cost mixing.

bauma premiere: Mixing high-abrasive material with minimum abrasion

The first twin-shaft batch mixer in the new DKXK variant for producing sand-lime bricks.

At bauma 2016, BHS-Sonthofen is introducing a new generation of twin-shaft batch mixers of type DKXK that features a rubber trough specially designed for producing sand-lime bricks. This new type of batch mixer features particularly low wear to the trough – an important factor when processing abrasive mixtures such as sand-lime bricks.

The new DKXK version that BHS has developed for the proven twin-shaft batch mixer is optimally adapted for producing sand-lime bricks. This new innovation allows this industry to take advantage of BHS-Sonthofen twin-shaft mixing technology. The results are homogeneous mixing, short mixing times and low wear. The intensive mixing process also utilizes a high percentage of the lime used in each mixture, which in turn produces a very dense packing mixture.

The first mixer in this new generation – which has a 2,300-liter capacity – will start operations in February 2016 in Baden-Baden (Germany) as the main mixer upstream of the reactor. Since 1971, the client has been operating a BHS-manufactured twin-shaft batch mixer of similar design that they are now replacing with a more powerful state-of-the-art unit.

Sand-lime bricks are made of sand mixtures containing a high silicate, quicklime and water content. This material is highly abrasive. Considerable wear occurs in previously used conventional mixing systems such as intensive mixers. The reason so much wear occurs is because the fine sand acts like sandpaper on the mixing tools and on the mixer’s trough wall.

BHS has therefore specifically developed the DKXK type of mixer for producing lime mixtures as an alternative version to the world’s proven DKX type of twin-shaft batch mixer. Instead of a steel trough with a lining made of wear tiles, BHS builds their sand-lime brick mixer with a rubber mixing trough that pulsates when mixing, thus effectively preventing sticky mixing material from caking. This reduces blade and trough lining wear as well as reduces the engine’s power consumption.

This solution has long proved itself as one of BHS’s very reliable single-shaft continuous mixers. DKXK can optionally equip the mixing blades with Widia (tungsten-carbide) plates, which significantly increases service life.

The new DKXK mixer variant offers several advantages when compared with the intensive mixers that have been used in the sand-lime brick industry until now: In contrast to the circular motion of other mixing systems, the three-dimensional mixing principle of the twin-shaft batch mixer produces a more intensive exchange of material. This results in shorter mixing cycles with the effect of a lower energy consumption. In addition, the mixer requires less maintenance because wear parts are easy to replace.

This is another reason why the twin-shaft batch mixer by BHS-Sonthofen is an economical alternative for producing sand-lime brick mixtures.

In the future, BHS-Sonthofen will offer the DKXK twin-shaft batch mixer for the sand-lime brick industry with a filling volume ranging from 1,000 to 6,500 liters.

Background: Twin-shaft batch mixers of the DKX series

The twin-shaft batch mixers from BHS-Sonthofen have a mixing mechanism whose arms, which are in the form of an interrupted spiral, are arranged on two counter-rotating mixing shafts. They generate a circular, three-dimensional movement with intense material exchange in the turbulent overlap area of the two mixing circuits. Counter paddles on the shaft ends redirect the entire material, so that it is repeatedly returned to the mixing process.

They achieve a higher mixing effect than comparable single-shaft or intensive mixers as all the material is constantly in movement even at low speeds – and at significantly lower energy consumption.
In contrast to other mixer systems, twin-shaft batch mixers can be filled to a much higher level, so that they are more compact with the same throughput. Thus in new-build plants the mixers score points with their small dimensions. Moreover in case of retrofit and plant modifications in existing installations a more powerful mixer can be installed.

About BHS-Sonthofen

BHS-Sonthofen is an owner-operated group of companies in the machinery and plant engineering field, based in Sonthofen, Germany. The company offers technical solutions for mechanical process engineering, concentrating primarily on mixing, crushing, recycling and filtration. With more than 350 employees and several subsidiaries, BHS-Sonthofen has a global presence.

The Mixing Technology division produces batch and continuous mixers with single and twin-shaft technology and offers a full range of process technology for mixing. The spectrum extends from conventional applications in the concrete industry for transport, precast, dam or high-performance concrete and the mixing of dry mortar, cement, mineral mixes, landfill construction materials or other bulk materials to the conditioning of sludges, the production of suspensions or applications in mining.

For more information, see www.bhs-sonthofen.de.

Firmenkontakt
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

Pressekontakt
VIP Kommunikation
Regina Reinhardt
Dennewartstr. 25-27
52068 Aachen, Germany
+49.241.89468-24
reinhardt@vip-kommunikation.de
www.vip-kommunikation.de

Science Research Technology

BHS-Sonthofen: Twin-shaft batch mixer for the Kressbronn concrete plant

BHS-Sonthofen: Twin-shaft batch mixer for the Kressbronn concrete plant

The twin-shaft batch mixer provides a lot of space on the new mixer platform.

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

Pressekontakt:
VIP-Kommunikation
Regina Reinhardt
Süsterfeldstrasse 83
52072 Aachen, Germany
+49.241.89468-24
reinhardt@vip-kommunikation.de
http://www.vip-kommunikation.de