Economical alternative to wet processing

Combimix system


Combimix processes (DKXC)

The patented Combimix system transforms the twin-shaft batch mixer (DKX) into a mixer that operates continuously according to the proven three-dimensional mixing principle. This results in a more intense mixing effect and a significantly longer average retention time compared to conventional continuous mixers. The material is extracted at the same rate as the input material is fed into the system.

BHS Combimix process for processing clay-and-rock mixtures in quarries

171012_BHS_Combimix-MSW-DREP2016_ENG_final - Original.mp4

BHS Combimix process for processing clay-and-rock mixtures in quarries

This nomination video for the German Resources Efficiency Award 2016 introduces the BHS Combimix process for processing clay-and-rock mixtures at the Mönsheim quarry operated by MSW Mineralstoffwerke Südwest

Advantages compared to wet processing

  • No introduction of moisture into the aggregates
  • No wet sieving
  • No sludge processing
  • All materials are recycled, saving landfill space
  • Compact system also available as a semi-mobile version
  • High level of rock reclamation
  • Possible to screen out material smaller than 5 mm

Advantages compared to conventional continuous mixers

  • Continuous mixing process with a defined mixing time, which helps to reduce consumption of expensive burnt lime
  • Three-dimensional mixing principle
  • Consistently high mixture homogeneity
  • High throughput rates
  • Low wear


Previously, cost-intensive wet processing was necessary in order to extract valuable rock grade from contaminated input material. Dry processing with the addition of burnt lime is not possible with conventional continuous mixers due to the extremely short retention time and poor mixing effect. The patented BHS Combimix system was developed to offer an economical alternative.

The Combimix system transforms the twin-shaft batch mixer into a mixer that operates continuously according to the proven three-dimensional mixing principle.

This results in a significantly improved mixing effect compared with conventional continuous mixers. The retention time is dependent on the input material and can be varied flexibly from 30 to more than 100 seconds. The filling level is kept constant over the entire production time by means of weight sensing in the mixer. The material is extracted at the same rate as the input material is fed into the system. This procedure enables the recovery of usable rock, while also saving on water, energy and material costs.

Process steps

1. The raw material is fed in.

2. Pre-separation is performed over a roller screen.

3. The coarse-grain material is transported directly to the jaw crusher and from there to the quarry plant.

4. The clay-and-rock material is fed into the BHS Combimix system and combined with burnt lime.

5. The burnt lime is delivered from the silo by way of volumetric metering into the mixer on a screw conveyor (according to the clay content in the feed material of between 1 and 5%). A weight-based approach is available on request.

6. The mixing material is fed into the screening unit.

7. Materials larger than 5 mm are made available for further processing.

8. Materials smaller than 5 mm can be used as fertilizer, for example, where appropriate.

Technical specifications

TypeThroughput 1)Max. particle sizeweight 2)

DKXC 1200

85 t/h42 mm3.900 kg

DKXC 2600

180 t/h64 mm5.900 kg

DKXC 4900

350 t/h120 mm10.400 kg

DKXC 7300

520 t/h120 mm18.500 kg

DKXC 10800

770 t/h150 mm28.000 kg

DKXC 12900

920 t/h150 mm37.000 kg

1) 60 s mixing time and density of 1.7 t/m³
2) Weight for standard design without accessories

Performance data for other materials available on request. All specifications apply to the standard design. Technical data for customized designs may differ from the specified data.
All technical data may change due to development. Subject to modification without notice.

Application examples

Feed material 0 - 40 mm: sticky, loamy, which is considered waste
Screened material > 5 mm after Combimix mixing process
Sieved clayey material < 5 mm with quicklime
Mixed material with quicklime


Tests give certainty

Which mixer is the right one for your application? Don’t leave anything to chance. Leave it to our team of process consultants. Working together with you, our specialists will test the material and develop a tailor-made solution for you.
“Combimix system (DKXC)” brochure
“Mixing & crushing” overview brochure
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Success stories

Two BHS mixers in Europe's largest precast concrete plant

May 2024
In Mikkeli, Finland, the largest precast concrete plant in Europe relies on the innovative mixers from BHS-Sonthofen to produce prestressed concrete elements for industrial buildings and commercial premises. Thanks to the outstanding performance of the BHS twin-shaft batch mixers, high-quality concrete products can be produced on a large scale.

Four large BHS mixers for a land-reclamation project in Hong Kong

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Hong Kong is in the midst of a housing crisis. The megacity is bursting at the seams, with the government always on the lookout for new properties. Many residents also depend on living near the city center, in close proximity to its towering financial headquarters. To address this problem, Hong Kong has been working to reclaim land from adjacent bay areas for many years. The TKO project in the east of the city is part of this effort. For this prestigious project, BHS-Sonthofen has supplied four large twin-shaft batch mixers of type DKX 5.00 for the production of concrete.

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Three prestigious projects with BHS twin-shaft batch mixers in Australia

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Two major operations are not enough to push the twin-shaft batch mixer from BHS-Sonthofen to its limits. Since their first use over 12 years ago, two BHS twin-shaft batch mixers of type DKX 6.00 have proved to be indispensable heart of some Australia's most significant construction projects. Three prestigious projects stand as living examples of the efficiency, reliability and outstanding performance of BHS mixers.

BHS mixer with 28,000 liter capacity for mine backfilling in India

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An exciting event has taken place in the world of mining: A gigantic BHS twin-shaft mixer of type DKXC with a filling capacity of 28,000 liters has been successfully integrated into a mine backfilling plant in India. The size of this mixer is not only impressive, but also makes it a real eye-catcher in the plant.

National Museum of China displays sample of RCC mixed with BHS technology

February 2024
It is the largest sample of Roller-Compacted Concrete (RCC) in the world! And it is the result of a big project. The Dagu Hydro Dam is located 3,700 meters above sea level, making it the most elevated site ever for employing BHS twin-shaft batch mixers. A core sample of the dam was extracted in 2021. Due of its size and excellent quality, the National Museum of China chose to include it in its collection for public display in 2023.

Ten BHS mixers for China's high-profile Pinglu Canal project

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China is a country of superlatives, not least in terms of population: With more than a billion people and huge agricultural areas, securing a continuous supply of water for the nation has become paramount. Reservoirs and dams help store water and regulate its distribution, especially in times of drought or water rationing. Over the past few decades, China has therefore embarked on a series of major construction projects. One of the currently most important projects is the Pinglu Canal Project, for which BHS-Sonthofen has supplied eight large BHS twin-shaft batch mixers of type DKX 7.00 and two additional DKX 4.00.

Express solution for mixing plant at Cemex Matériaux Ile-de-France

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What to do when time has taken its toll on a proven mixer, and a replacement is needed quickly? Cemex, an international manufacturer of building materials, needed a new BHS twin-shaft batch mixer for its plant in the Paris region at short notice. Thanks to high machine availability and precise construction plans, BHS-Sonthofen provided on-the-spot delivery and ensured the seamless integration of the new mixer into the concrete plant in record time.

BHS test center: Successful testing of building materials

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„Just do it“ occasionally proves to be an extremely efficient strategy. Especially when it comes to finding out more about the processing of various raw materials for building applications. BHS-Sonthofen offers an ideal environment with its test center, which opened in 2019. Upon customer request, the company conducts intensive field tests with various materials – with great success.

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The demand for higher construction quality, especially centrifugal concrete, challenge Vietnamese companies to use new technologies. Minh Duc Concrete and Construction Co., Ltd is one of the leading companies in the field of production, supply and construction of spun concrete piles in the Vietnamese market and relies on the proven BHS technology in many projects.

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The city of Constantine is at the heart of Algeria's booming economy. Across the country, infrastructure construction is experiencing an enormous upswing – which in turn requires a high availability of building materials. Batinol Construction s.a.r.l., which is based in Constantine, produces limestone sand for cement and concrete applications. Since January 2022, the company relies on a rotor centrifugal crusher of type RSMX 1222 from BHS-Sonthofen for processing the delicate raw material.

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At the former Pier 55 along the Hudson River in New York, a bed of concrete tulips now rises out of the water: 132 of these precast tulip elements, mounted on 267 prestressed concrete piles, form a 2.4-ha artificial island and are the new eye-catcher of the waterfront. For the ambitious project, precast producer and supplier of the concrete flowers Fort Miller Co., Inc. used the proven mixing technology of BHS-Sonthofen – two BHS twin-shaft batch mixers of type DKXS 3,00 ensured concrete of the highest quality.

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