Mixing concrete for more than 1,100 wind turbines is no small task. Tecwill Oy, a Finnish expert for concrete batching plants, puts his trust in a twin-shaft batch mixer from BHS-Sonthofen. The mixer produces 4 m3 of fiber concrete per batch and allows for casting up to three windmill bases per day. Tecwill and his customer particularly praise the mixer for its reliability and the efficiency of the time- and cost-saving mixing principle.

In the North of Sweden, Ruskon Betony Oy is involved in building one of the biggest wind farms in the world: The first building phase includes 176 wind turbines, with 440 more turbines to follow. In total, the Markbygden Wind Farm will consist of more than 1,100 wind turbines which produce up to 4,000 Megawatt of green energy. The bases of the windmills consist of about 600 m3 of fiber concrete each. To ensure the concrete is of high quality and readily available when needed, Ruskon tasked Finnish concrete plant expert Tecwill with constructing a mobile plant. To meet the requirements on site, the plant consists of five aggregate bins, four cement silos, a fiber dosing module and a turbo-heating container including a buffer tank for cold water. At the heart of the batching plant is the twin-shaft batch mixer of type DKXS 4.0 from BHS-Sonthofen with an output of 4 m3 compacted concrete per batch.

Reliable partner for custom-sized mixers

For Tecwill, it is important that the mixer fulfills the following requirements: cost and energy efficiency, full reliability, short mixing times combined with a very good homogeneity, and the mixer has to fit into the plant.
Especially when the client needs a mobile plant, the actual size of the mixer plays a crucial role. Mika Silvennoinen, Area Sales Manager at Tecwill, explains, why this is one of the many reasons the Finnish company prefers mixers from BHS: “Next to the option of choosing between different customizations, we can decide how large the mixer shall be – often the standard size already fits well into our plants. When it does not, we ask for a custom-made model. Either way, the external dimensions of the mixers are relatively small compared to a large batch size. Another plus is the low mixing time – even when processing special mixtures.”

Quick mixing of demanding concrete formula

For one batch of the fiber concrete used to cast the base of the windmills, the mixer takes about six minutes. Manfred Immler, Area Sales Manager for West Europe at BHS explains the secret behind the advantages of this type of mixer: “Our company has been building twin-shaft mixers for more than 130 years and our engineers have continuously improved the technology. Our experience and know-how lead to a lot of designing and engineering details, which make the difference in the end. The DKX is the number one choice for demanding large-scale projects.”

The mixer used for building the Markbygden wind farm is able to produce about 120 m3 of regular concrete or 90 m3 of the more demanding fiber concrete per hour. On a regular day with two work shifts of eight hours, the mixer produces material for the bases of two windmills – allowing for quick progress in this impressive project. “If the plant would run 24 hours a day, it could even mix concrete for up to three windmill bases – for the mixer this would not be a problem,” Mika Silvennoinen concludes.

For thirty years, Tecwill has been using twin-shaft batch mixers from Sonthofen. Especially in large projects, where maintenance-free appliances and high-quality output are of utmost importance to guarantee seamless processes, BHS is the provider of choice. “Many of the companies we work with specifically ask for a twin-shaft batch mixer made by BHS-Sonthofen,” says Silvennoinen. “Though it might cost a bit more than other brands, its reliability and efficiency in terms of time and energy saving pay off quickly. Our clients are always very happy with the mixer.”