Concrete is increasingly used not just for construction but also for the purpose of aesthetic design. As a main component of concrete, special cements open up new options for colouring and moulding. To permit efficient production of these high-quality cements, Gebr. Lödige Maschinenbau GmbH has added not just one, but two construction material mixers, the SEM and the DBE, to its portfolio. They are especially designed for tasks requiring a high mixing quality and a high throughput rate in batch production. It is, among other things, special solutions for quick machine draining that make this possible.
Both the quick-drain mixer SEM and the DBE batch mixer operate according to the mechanically generated fluidised bed process introduced to mixing technology by Lödige. Ploughshare shovels arranged on a shaft rotate in the horizontal cylindrical drum as mixing elements. They subject the powdery, granular or fibrous bulk materials to three-dimensional action, mixing the entire product quickly and precisely. Treatment of the product in this process is exceptionally gentle, as the special shape of the tools ensures that the product to be mixed is picked off the drum wall during the radial movement while reliably preventing destruction of the particles. The homogeneous distribution of ultra-fine components – for instance colour pigments –achieved by this process is crucial for the quality of the product, particularly in special cements. In addition to the high mixing quality and reproducibility of batches, high throughput rates are a key factor of competitiveness in the construction material industry. Lödige batch mixers are adapted to these requirements, not only due to their short mixing times but also due to their optimised draining system.
Drained in seconds – Quick-drain mixer SEM
A high production volume was Lödige’s focus when developing the quick-drain mixer SEM. To achieve this, the mixer was equipped with an especially large pneumatic discharge flap spanning across the entire length of the mixing drum. An opening angle of 60° permits practically residue-free draining within only two seconds. However, the rapid draining function is not the only feature responsible for this machine’s high throughput rate. The SEM is also designed for quick filling and short mixing times: Approximately 20 batches can be processed per hour. For solid substance mixtures, this means high throughput rates with intermittent operation. This model makes even frequent product changes more efficient. The SEM is available in four sizes with a drum volume between 1600 and 3000 l. As an option, the mixer is also available in an ATEX version for explosive environments.
Short cycle times – DBE batch mixer
With an outfeed opening designed to span across the entire drum length, the DBE batch mixer also guarantees practically residue-free product draining in no time at all. To achieve an opening angle of 90°, the Paderborn-based mixing experts implemented hydraulic opening and closing of the overall cylindrical drum including the head segments. The result is that the entire process of feeding, mixing and draining only takes approximately two minutes. This mixer designed especially for construction materials operates with exceptional efficiency, processing approx. 30 batches per hour. The sophisticated machines of the DBE range are available in drum volumes from 300 to 8000 l: The largest machine can handle a throughput of approximately 235 t/h.
High availability through sophisticated design
When producing special cement, the product quality depends not just on the dispersion but also on the correct dosage of the individual components. A highly precise addition of materials with regards to quantity and addition time is particularly necessary where colour pigments are involved. Lödige mixers meet all requirements for a simple and customisable feeding process due to their special design feature: A large nozzle plate arranged across the entire drum length on the feeding opening permits variable positioning of individual component supply points depending on the specific requirements and makes retroactive expansions or conversions possible.
The common features of all mixing and treatment systems developed by Lödige for the construction material industry are high availability and minimised downtimes. For instance, the optimised draining technique significantly minimises residue volumes in batch mixers of both the SEM and DBE range, which leads to a considerable reduction of the effort and time required for cleaning in the event of recipe changes. In addition, special nozzles speed up the process by air-blasting the product for quick, dry cleaning. Moreover, the wear-proof design of mixing tools and choppers guarantees a long service life even when used for highly abrasive materials such as cement, thereby ensuring high availability. Should wear parts require replacement, easy access to the mixer interior permits simple inspection and maintenance.
Special cement makes particular demands of the production process. A homogeneous mixture is therefore crucial for achieving the desired result later on. At the same time, it is necessary that the required mixing quality is achieved in as little time as possible. Lödige provides solutions to these problems with its SEM and DBE batch mixers. Both machines are equipped with an optimised draining system. Extra-large flaps spanning across the entire length of the mixing drum make it possible to drain the machines within seconds.