BHS-Sonthofen will be presenting its wide range of mixing and crushing technologies at this year’s bauma in Munich. The team is looking forward to meeting its customers, distributors and partners in person again from 24-30 October 2022 at booth 449 in hall B2. At the world's leading trade show, the technology expert will be exhibiting the twin-shaft batch mixer, which is considered the benchmark in mixing technology, as well as a single-shaft continuous mixer, a rotor impact mill and a rotor centrifugal crusher on a total floor space of 391 m2.
“The machines are clearly the main attraction at bauma. That’s why we keep the lid open when we present our machines – so that visitors can take a look at the inner workings of our mixers and crushers,” says Bahar Yerlikaya, Marketing Manager for the Building Materials Machinery division at BHS-Sonthofen and emphasizes: "We are pleased to be present again on site in Munich for our customers and partners after an interruption of almost two years. After all, digital technology cannot replace personal contact."
The right mixer for every project
At the BHS booth, the twin-shaft batch mixer of type DKXS 4,50 takes center stage. In major projects throughout the world, the twin-shaft batch mixer from BHS-Sonthofen is being used to produce all types of concrete. Due to the increasing demand for fast and efficient construction, the demand for high-performance mixers continues to rise as well. The DKXS 4,50 is particularly suitable for industrial mixing processes in the medium to high output range and delivers four and a half cubic meters of hardened concrete per batch. The three-dimensional mixing principle of the mixer leads to a more intensive material exchange and thus to shorter mixing times with less energy requirement. At bauma, visitors can learn about the standard mixer’s globally proven, comprehensive modular system and the wide range of mixer sizes and accessories that are available.
In addition to the twin-shaft batch mixer, BHS will also be presenting a single-shaft continuous mixer of type MFKG 0520 at bauma. With its continuous mixing system, the mixer is the right solution for mixing fine materials – whether dry, moist, pasty or suspension-like mixtures. The special feature of the BHS single-shaft continuous mixer is the self-cleaning rubber trough, which prevents caking of hardenable mixing material on the inner wall of the trough.
Efficient crushers for stone and sand production
With its continuous mixing system, the mixer is the right solution for mixing fine materials - whether dry, moist, pasty or suspension-like mixtures. The high-performance crusher with vertical shaft is ideally suited for the production of quality sand. BHS will also present a rotor centrifugal crusher of type RSMX 1222, which is used for crushing and refining mineral materials.
At the former Pier 55 along the Hudson River in New York, 132 precast tulip elements, mounted on 267 concrete piles, form a 2.4-acres artificial island. They are the new eye-catcher of the waterfront. For the ambitious project, precast producer and supplier of the concrete flowers Fort Miller Co, Inc. relied on the proven mixing technology from BHS-Sonthofen – two BHS twin-shaft batch mixers of type DKXS 3,00 ensured concrete of the highest quality.
The planning phase for Pier 55, now known as "Little Island", dates back almost ten years, with the foundation stone being laid in 2018: Concrete piles had to be driven into the ground to make the island, designed to accommodate several thousand people, possible. The project was realized through partnership with the Hudson River Park Trust and funded primarily through Barry Diller and the Diller-Von Furstenberg Family Foundation. The free public park pier within the larger Hudson River Park opened in May 2021.
Highest concrete quality for aesthetics, expediency, and durability
BHS-Sonthofen was already involved in the project during this first phase. Precast concrete manufacturer Coastal Precast Systems from Chesapeake/Virginia uses BHS mixing technology at three of their sites. They supplied the necessary 267 up to 60 m long post-tensioned precast concrete piers for the substructure – each with a load capacity of 250 - 300 tons.
In the subsequent project phase with Fort Miller from Schuylerville/NY, the architecturally appealing precast concrete structures were placed. Weighing 90 tons, each of the 132 tulip heads is intended to be both delicate and function as an oversized flowerpot to support the park and entire trees. Fort Miller accepted this challenge and purchased two BHS twin-shaft batch mixers, each with a discharge of 3 m3 per batch, for this and other ambitious orders. "Concrete components in close proximity to the tidal sea water are subject to constant corrosion. The mixing technology from BHS-Sonthofen ensures the highest mixing quality, which is essential in such projects," explains Scott D. Harrigan, president of Fort Miller. The proven technology enabled the production of 655 individual tulip leaves, which were trucked to the port of Coeymans and assembled before being barged to the site.
Mixing technology optimized for customer requirements
With more than 130 years of experience with mixing technology, BHS-Sonthofen is the right partner for ambitious challenges. “The DKXS is the optimal choice for precast concrete of highest quality”, explains Mike Kerins, Sales Manager Concrete and Minerals Division at BHS-Sonthofen Inc. “The three-dimensional mixing concept of the mixer results in an intensive exchange of materials, shorter mixing cycles with reduced energy consumption, and a maintenance-friendly and robust design. Furthermore we are centrally located on the East Coast where we have our sales and warehousing operations that can quickly adapt for orders and service needs. Fort Miller has been a great partner to BHS, and we are honored to continually be an integral part of their manufacturing process,” Kerins sums up the successful project.
The Italian manufacturer of planetary mixers Eurostar Concrete Technology S.p.A. and BHS-Sonthofen have joined forces as of March 18, 2022. With the sale to a highly recognized partner, Eurostar’s Managing Director Mario Zaccaron is strengthening the company’s position and ensuring its further development. At the same time, BHS-Sonthofen is expanding its own portfolio of twin-shaft batch concrete mixers to include high-quality planetary mixers for building materials applications for batch sizes up to 6,000 liters. The added solutions will offer customers of both companies additional equipment and service flexibility.
Planetary mixers are widely used to produce precast concrete parts, such as concrete blocks and pipes, as well as special concrete designed for environmental purposes and in the glass industry. By purchasing the Italian manufacturer, BHS-Sonthofen acquires a key technology in the building materials industry, which expands the existing mixer portfolio with another widely used mixing method. In this way, BHS-Sonthofen aims at consolidating its position as a technical expert for quality mixers in the long term. “The combination of twin-shaft batch mixers and planetary mixers as well as other types of mixers enables us to respond more specifically to our customers’ demands,” emphasizes Dennis Kemmann, Managing Director at BHS-Sonthofen. These requirements not only include a flexible choice of equipment for a wide range of tasks, but also a reliable and vast service network. Thanks to the integration of both companies, Eurostar customers will benefit from several additional BHS service hubs and a thorough spare parts management across the globe. “For plant manufacturers and sales partners, the expansion means an even more attractive product portfolio at a high technological level and with robust drive technology.”
Like the twin-shaft batch mixers from BHS-Sonthofen, the machines from Eurostar Concrete Technology have specially designed robust drives. In addition, the business models of both companies complement each other: Eurostar and BHS both act as manufacturers of mixers for end customers, plant manufacturers and resellers. “Among many others, this is a further reason why BHS-Sonthofen is the best partner for us,” explains Mario Zaccaron, Managing Director of Eurostar Concrete Technology S.p.A. “Both Eurostar and BHS-Sonthofen will equally benefit from the acquisition. Thanks to BHS-Sonthofen’s experience and its extensive network, we can produce even more efficiently and open new markets.”
Mr. Zaccaron remains Managing Director of Eurostar Concrete Technology, ensuring the continuity of business activities from Eurostar’s site near Udine in Italy, with the aim to further improve and strengthen the company’s position.
Van Nieuwpoort Prefab Beton has been producing precast floors for more than a century and continuously invests in new construction technologies and efficient production methods. In one of their concrete plants, BHS-Sonthofen and Loke BV have equipped an existing plant with a BHS twin-shaft batch mixer of type DKX 3,00 and optimized the plant. Since then, optimum mixing results have been achieved for concrete used in the production of floorboards and the plant output has been significantly increased.
The mixer that was previously in use would not have had to be replaced yet. But the existing machine could not produce the concrete with the required homogeneity. After installation, the advantages of the BHS twin-shaft batch mixer, which is considered to be the benchmark in the industry for good reason, became clearly visible: With the same size of mixer, the homogeneity of the concrete has been significantly improved.
One of the reasons for this is the three-dimensional mixing principle of the DKX, which leads to a more intensive material exchange. This takes place in the highly turbulent overlapping area of the two mixing circuits. In this way, the BHS twin-shaft batch mixer produces mixtures of consistently high homogeneity in a short time. Furthermore, the size and design of the mixing blades play an important role.
The main goal was to increase production capacities. “Thanks to the new mixing technology, the customer produces the same number of floorboards in 16 hours as before in 24 hours”, explains Peter Loke, Managing Director at Loke B.V. This significant increase in productivity not only benefits Nieuwpoort, but also suits Loke and BHS-Sonthofen.
The Chinese-Pakistani consortium CEC-POWERCHINA and the Pakistan Frontier Works Office is building the Diamer-Basha Dam near the Chinese border in northern Pakistan. The construction project will require 18.6 million cubic meters of mainly roller-compacted concrete over the next few years. BHS-Sonthofen has received a contract to deliver six BHS twin-shaft batch mixers to Pakistan at its Chinese site in Tianjin to meet its concrete demand. Two of the mixers have already been manufactured and delivered.
The construction project is of key importance for Pakistan in terms of energy policy and also represents closer cooperation between Pakistan and China. The dam is being built on the Indus River in northern Pakistan and will form a reservoir approximately 40 kilometers downstream from Chilas. The world’s largest dam is planned to be 272 meters high and is expected to use 17.1 million cubic meters of roller-compacted concrete and 1.5 million cubic meters of ordinary concrete.
Twin-shaft batch mixer – the optimal choice
BHS-Sonthofen in Tianjin received a contract to supply a total of six BHS twin-shaft batch mixers for this major project, two of which are already constructed and delivered. The delivery includes four mixers of type DKX 7.00 with 7 m3 of hardened concrete per batch and two mixers of type DKX 6.00 each with 6 m3 of hardened concrete per batch. Ronny Laux, General Manager at BHS-Sonthofen’s Tianjin site, is responsible for the construction and delivery of the mixers: “The hydraulically bound base layers required for the dam, also known as ‘roller compacted concrete’ (RCC), must withstand the heaviest of loads. Our mixers are designed to handle demanding mixing tasks. The twin-shaft batch mixers meet the highest demands for mix homogeneity and reproducibility, even with large quantities – ensuring optimum concrete quality.” The low wear on the mixing tools and the mixing trough lining (thanks to the low speeds and compact design) contributes to the fact that the machines are in high demand for large projects in particular.
Additional mixers are planned
Two of the mixers manufactured in Tianjin have already been built and delivered to the large construction site. The remaining four are due to follow by the end of the year. The cooperation with BHS-Sonthofen went so smoothly that the customer suggested the prospect of a follow-up order even before delivery. “BHS is expected to deliver another six mixers next year,” says Laux, commenting on the progress of the project. “Having a location in Tianjin allows us to combine our expertise with regional proximity to the customer – this creates trust. Maintenance services can be provided or spare parts can be delivered quickly and easily.” According to the current plan, the dam’s construction period will end in 2029.
What is to be done when there is no empirical data for the production conditions of using a mixer in advance? And what to do furthermore if the construction site of the mixer is difficult to access? These were the initial conditions that BHS-Sonthofen had to contend with as part of the ARGE ETS Konrad mine project in Salzgitter-Bleckenstedt, Germany. It had to design a BHS twin-shaft batch mixer and deliver a custom-designed mixing plant.
The mixing plant will produce wet shotcrete (0-4 mm) from dry compound with different concrete additives and achieve an optimum end product – in a mine located 1,000 meters underground.
“We use the BHS laboratory mixer of type DKX 0.06 S to meet any requirement for which we still do not have any example cases available in our portfolio of previous projects,” explains Eckhard Rößner, who is responsible for the building materials machinery sales force in the region. Those responsible at the ARGE ETS mine used this scaled-down version of the large BHS twin-shaft batch mixer to test what the optimal design for the ready-mixed shotcrete (grain and cement) would be and how it needed to be processed for use in the mine. To be more specific, the mixing plant should produce 20 to 25 cubic meters of wet shotcrete per concrete pour with a concreting time of four to six hours. The consistency range for the finished product is F2/F3. The key here is maintaining the exact water-cement ratio of 0.45 set out in the requirements specified for exposure class XA3.
A successful test led to a successful order
To get the best idea of how the BHS twin-shaft batch mixer works and the results it delivers, the cooperation between ARGE and BHS started with the rental of the laboratory mixing station. The team performed a two-stage test starting in August 2020. The first stage took place on the premises of ARGE stakeholder Schachtbau Nordhausen, with the second stage then taking place underground. They tested all of the functions and performance features of the mixing system, as well as the combination of dry mixes with additives from various suppliers. “It was important for us to experiment and develop the ideal product characteristics before investing in a large plant. The laboratory system from BHS provided the perfect conditions for us to do this in,” emphasizes Marcel Hahn, a project manager at ARGE. To produce wet shotcrete underground, a dry compound from big bags with a maximum grain size of 4 millimeters is used to which steel fibers are added during the mixing process. Once the concrete is mixed, the end product is loaded into a special truck mixer that has a capacity of 3.5 cubic meters and is transported to the concrete pump.
Complicated logistics for onsite installation
ARGE ordered the custom-designed BHS “Stabimix 0.75” mixing plant at the beginning of October 2020 following the successful test with the machine in the lab. In addition to the BHS twin-shaft batch mixer of type DKX 0.75, the delivery scope also included all of the peripheral equipment and a process and dosing control system developed inhouse by BHS’ control systems department. Equipment designed to make the already difficult working conditions underground easier to deal with, such as a high-pressure cleaning system for the mixer and a central lubrication system, rounded off the delivery scope. “After we had placed the order, we still had a few logistical demands to deal with in terms of having the installation components delivered,” explains Rößner. “We couldn’t simply deliver and install the plant and equipment in the same way we normally would at other sites. Instead, we had to deliver them divided into logical individual components and transport them to a depth of 1,000 meters using a shaft hoisting system.”
The clear specifications for the dimensions of the components and transport containers included a maximum component format of 2,300 mm deep x 2,700 mm wide and a maximum weight of 5,000 kilograms. In total, BHS transported around 45 individual pieces down to the mine in line with these project specifications. Delivering and transporting the components underground were not the only things that required meticulous planning – everything from the location of the hoist to where the mixer will actually be used (an area of approx. 3 km) on a base measuring 1,000 meters did, too. The final installation process also had to be designed using completely different work steps to the usual procedure, since deliveries are normally comprised of much larger assemblies than the one at this underground construction site. Tools and work materials were planned with safety reserves, as the complex logistics of the situation meant additional deliveries would not arrive quickly enough.
Laboratory machine guarantees reproducible mixtures
Installation onsite started at the beginning of February 2021. To this end, BHS installation specialists prepared themselves for working underground. A lead installation technician, an electrician and a control specialist underwent a physical specifically for this task and receiving training in working underground and the occupational safety regulations that apply in that environment. The batch mixer and its peripherals were installed and commissioned in around four weeks with the support of ARGE personnel. “Production with the BHS plant went live in the early part of summer 2021 and we can implement the exact conditions we tested in the lab here underground. It worked really well. That’s why we decided to buy the machine from the lab as well,” says Hahn. “This also allows us to perform detailed dosing and mixing tests for other projects before we start them since the lab results are representative of the production machines.” This means that ARGE ETS has the safest operation possible when it comes to concreting work in underground projects as a result.
To get the maximum from limestone at the CMSE - Carrière de Saint-Colombe quarry and produce more valuable fine sand, the French Colas Group employs the BHS rotor impact mill of type RPMF. With this high-performance crushing technology, Colas achieves high reduction ratio and excellent particle shape. The fine sand is used for asphalt production.
No naturally formed rock is as versatile as limestone. When crushed down to a fine particle size, the material is particularly suitable as a component of asphalt mixtures. A few years ago, the French Colas Group, a major international player in road construction, researched how to extract even more valuable sand from the existing rock for its own asphalt production site at Perpignan in Southern France.
The rock comes from a quarry in the proximity of Thuir and Saint-Colombe, not far from the city of Perpignan. The quarry that extracts a hard limestone has been established for more than 50 years. In 1979, the quarry was equipped with a crushing plant under the name of Roussillon Agrégats, allowing the materials to be used for construction. In the early 1990s, the COLAS Group became the owner of the extraction and production sites.
Since then, the company has made many investments into the technology used at the quarry now known as CMSE - Carrière de Saint-Colombe. It employs big impact crushing machines that produce sands in different categories. In the course of time, new technical options became available - also through consulting of BHS-Sonthofen. To improve the material even further and get more valuable sand from the limestone, Colas decided to add another stage to the crushing process. “The target was to crush the non-valuable grain sizes of limestone 3/6 mm and 6/12 mm to produce fine sand with grain size 0/3 mm in high quantity”, explains the customer.
For this crushing step, Colas turned to BHS-Sonthofen. “Together with the customer, we carried out several tests with the original material at the test center in Sonthofen,” says Alexandre Bernabé, Sales Director for the French market at BHS-Sonthofen. “This helped us find out how the machine must be configured and what performance we can actually achieve with our crushing mill.”
Unique crushing technology for high-quality sand
Colas opted for the rotor impact mill of type RPMF 1516 because of the machine’s unique operating principle. This high-performance crusher with a vertical shaft is suitable for crushing all low to moderately abrasive minerals and is therefore used predominantly in the production of sand for the concrete, asphalt and dry mortar industries. The machine enables Colas to achieve a high reduction ratio and excellent particle shape.
The impeller rotor of the BHS rotor impact mill is the only one of its kind worldwide. Due to the high circumferential speed of the rotor, there is an almost permanent gap between the tips of the horseshoe-shaped hammers and the anvil ring. The small gap width and the high energy input due to the circumferential speed result in a very high, targeted crushing ratio. Thanks to the narrower milling gap and the higher circumferential speed of the rotor, the material in the RPMF rotor impact mill is exposed to more intense stress. This distinguishes the RPMF, also called “the pulverizer”, from the RPM, which operates the same crushing principle.
“With its crushing principle, the RPMF really stands out from competition. Besides particle shape, the high productivity in the manufacturing of fine materials was another main argument for Colas to choose this machine,” Alexandre Bernabé comments. “Compared to other crushing technologies such as rotary mills, the ratio of tons and kilowatt is superior. For instance, we reach 50 tons per hour on average compared to 10-20 tons per hour with different technologies that consume much more power.” The rotor speed lies in the 80-90 m/s range.
A second argument is the low and uniform wear, which is based on the reverse rotation of the rotor. Every week the operator changes the direction of rotation. This way, a balance is achieved for all wear parts. With the effective dedusting system, operators can handle the wear of the machine easily.
The result, in percentage terms, is a higher proportion of fine sand. While grain size of the input material is 3/6 mm and 6/12 mm, the grain size of output is 0/3 mm with a high share of grains smaller than 1 mm. The product is internally used for asphalt production at Perpignan.
“Production has been running for some time, as the machine was put into operation in December 2017”, Alexandre Bernabé says. “The customer is very satisfied with the result and we are very pleased to have been able to help the Colas Group successfully implement this new crushing step.”
Concrete used in the construction of dams has to meet the most stringent requirements: it must withstand immense water pressure while at the same time being flexible enough to defy natural disasters. Producing concrete of this class requires high-quality mixing technology. This is why international customers such as SGTM and the Nachtigal Hydro Power Company (NHPC) rely on mixing plants from BHS-Sonthofen for their concrete dam projects. The mixers used in Morocco and Cameroon continuously produce large quantities of RCC (Roller Compacted Concrete) to ensure completion of the infrastructure-relevant dam projects.
Dams are seen as symbols of power and progress. They protect against floods and in many places ensure the supply of drinking water and energy. The demands on their construction and the materials used are correspondingly high – only special concrete of reliable quality is used for the construction of these gray giants: so-called “Roller-Compacted Concrete”. For its production, the Société générale des travaux du Maroc (SGTM), the Société de Travaux Agricoles Marocaine (STAM) and the Nachtigal Hydro Power Company (NHPC) from Cameroon rely on mixing plants from BHS-Sonthofen.
Three large dams under construction in Morocco
Morocco's water demand is rising continuously. In addition to agriculture, a wide variety of sectors are increasing their needs. In order to secure the population's water supply and forestall the threat of a drinking water deficit in 2030, the Moroccan authorities have initiated various construction projects for water reservoirs. One of these is the Tiddas Dam in the Khemisset region south of Rabat, which will be one of the country's largest dams when completed. With a capacity of around 592 million cubic meters and a cost equivalent to around 100 million euros, the Tiddas Dam is intended to secure the drinking water supply for Casablanca and Rabbat in the future. Following the groundbreaking ceremony in 2017, construction is expected to be completed this year. “The demands on concrete for the Tiddas Dam are high,” explains Hans Traut, Area Sales Manager Building Material Machinery at BHS-Sonthofen. “RCC concrete has a very low cement content, which makes it cost-effective but also very stiff.” Therefore, RCC cannot be pumped, but is brought in via conveyor belts and then compacted with rollers. Conventional, water-impermeable concrete is also used on the dam’s water side.
BHS supplied the complete MPL continuous mixing plant for processing the RCC, including the proven BHS twin-shaft continuous mixer of type LFK 9026 and sophisticated weighing, batching, and control technology. Traut comments, “The twin-shaft continuous mixer is a powerful, reliable solution for continuous mixing processes, especially with coarser grain content, as used for dam concrete.” Thanks to the continuous mixing process, the BHS mixing plant can produce up to 300 cubic meters of concrete per hour. “In addition, the mixing plant is unbeatable in its batching accuracy,” Traut continues. “We don't use bulk flow scales for our plants, but always work with double weighing, which allows us to achieve a deviation of only one percent in batching.”
For another dam project in Tinghir Province, contractor STAM purchased a used BHS continuous mixing plant refurbished with original spare parts. The Toudgha Dam is used for flood protection of the Toudgha Gorges, which are popular with tourists, as well as for irrigation of agricultural land downstream. The continuous mixing plant has now been in operation since 2019; the dam is scheduled for completion this year.
Nightingale Dam Project on the Sanaga River
The Nachtigal dam project in Cameroon is being built on the middle reaches of the Sanaga River northeast of the capital Yaoundé and is expected to be commissioned in 2023. It consists of roller compacted concrete dams, a headrace channel, a power plant with seven generating units, a substation and a transmission line. For the construction of this strategically important dam, BHS also supplied a complete continuous mixing plant with a twin-shaft continuous mixer type LFK 0926. “The robust and maintenance-friendly design of the LFK continuous mixer enables cost-effective and at the same time fast mass production of RCC with consistently high mixing quality,” says Traut.
The Dominican building materials manufacturer Calizamar, S.A. relies on crushing technology from BHS-Sonthofen. The company has commissioned the BHS rotor impact mill of type RPM 1513 to produce high-quality crushed sand. With this machine, there are now three crushing plants from BHS-Sonthofen in operation in the Caribbean.
In the building materials industry, not all sand is the same – and the same goes for countries blessed with picturesque Caribbean beaches such as the Dominican Republic. Not all naturally occurring sand has a form and composition that is suitable for the construction industry. In particular, the demand for dry and fine sand for dry mortar and concrete production is constantly increasing. That is why companies such as Calizamar need high-quality crushed sand with consistently reliable properties for their products. As its original mobile impact crushers were unable to produce appropriate crushed sand with the desired high cubicity, the search for new, suitable machines led Calizamar to BHS-Sonthofen.
The company opted for a BHS rotor impact mill of type RPM 1513. The high-performance crusher features a vertical shaft and delivers high crushing ratio as well as an excellent cubic particle shape. It is based on an impeller rotor that uses BHS’ unique crushing principle: the high circumferential speed of the rotor results in an almost permanent gap between the tips of the horseshoe-shaped hammers and the anvil ring. A small gap width and the high energy input due to the circumferential speed produce a targeted, very high crushing ratio. The result, in percentage terms, is a higher proportion of fine sand in the grain spectrum from 0 to 2 mm.
Imagine a company that wants to produce concrete for the new headquarter building using aggregate fractions from its own quarry? For E. Gfrörer & Sohn Schotterwerk GmbH & Co. this is actually a matter of course – if it weren't for the retrofitting of the tower batch plant virtually at the same time. BHS-Sonthofen proved to be the right partner for this time-critical project. The experts in mixing technology replaced two outdated pan mixers with a twin-shaft batch mixer, which was for the first time equipped with a speed controller with frequency converter designed by BHS-Sonthofen. In particular, this makes it possible to properly mix state-of-the-art formulations especially with very fine-grained fractions.
E. Gfrörer & Sohn Schotterwerk GmbH & Co.KG from Empfingen is an expert when it comes to stones and concrete: The company has been mining stone and processing it into various fractions in its own quarry in Sulz-Fischingen since 1924. In 1998, Gfrörer also invested in a plant for the production of ready-mixed concrete. Here, the gravel, stone chippings and crushed sands extracted and processed in an in-house plant could be directly used in the concrete production. The new line of business turned out to be a resounding success. This meant however that the two pan mixers in the mixing tower finally reached the end of their service life after a good two decades. New, state-of the-art mixing technology was to replace the two machines.
In August 2019, Gfrörer, together with BHS-Sonthofen, set out to plan the conversion of the plant. With the twin-shaft batch mixer of type DKXS 3.33, the ideal solution was quickly found. By formulating additional requirements to the mixer equipment, Gfrörer encouraged BHS to explore new avenues.
New technology for the proven mixing principle
State-of the-art concrete formulations contain ever higher proportions of extremely fine-grained aggregate additives. This allows the concrete to better penetrate the steel reinforcement. These fine fractions however pose a challenge for the mixing technology. In order to ensure optimum homogeneity with the most varied concrete formulations, BHS-Sonthofen together with Gfrörer decided to fit the twin-shaft batch mixer with a new technological feature: The proven three-dimensional mixing principle is supported by a speed controller with a frequency converter. The controller enables the speed to be changed during the mixing process, so that it can be best adapted to the corresponding formulation.
The new feature has another advantage, Gerd Schuler, BHS sales representative in the Building Materials Department, explained: “The customer’s power supply line is bidirectional. Gfrörer uses mains electricity and, if necessary, supplements this using a generator. The mixer must be able to handle both power sources. The speed controller has a stabilizing effect."
A tight schedule and a special first assignment
It kicked off at the beginning of 2020: After six months of planning, BHS was able to start retrofitting the plant on January 13. The timelines were strict: Gfrörer wanted to resume concrete production on February 24. A delay was out of the question, because the first project was to be a truly very special one, Uwe Gfrörer, the company's managing director, explained: “We were just about to build the new headquarters. Naturally, the concrete for the foundation should be produced in our own mixing plant using the materials taken from our own quarry plant."
In the first days of the retrofitting, the aim was to expand the existing weighing and mixing technology, including the steel construction. Only the storage silos for aggregates would continue to be used. The newly constructed weighing platform was equipped with an aggregate weighing batcher for gravel and sand, a cement weighing batcher, a water batcher, a chemical additive batcher, and an exhaust air filter. The mixing platform with the new mixer, into which all weighing batchers are emptied, was then fitted underneath. This tier is also fitted with a high-pressure cleaning system. The emptying of the mixer is controlled by a hydraulic unit located on the mixer. The mixer transfers the concrete either directly to the truck mixer through a discharge hopper or by means of a hopper extension for self-collectors. Here, landscape designers or private individuals can purchase smaller quantities of concrete for their projects.
“There were a lot of things to implement within this tight of a timeline,” recalls Gerd Schuler. “There was a certain degree of tension among all those involved. But we were well prepared." In fact, the retrofitting could hardly have gone any better. Instead of mixing the first batch of concrete on February 24 as planned, the system could already be tested on Wednesday, February 19. The result impressed us right away – the retrofitted plant was used for the foundation of the new headquarters. By the following Friday, the mixer had already produced a total of 250 cubic meters of concrete. "The fact that we were able to produce concrete for the new building in our mixing plant – and the fact that it was even ready four days ahead of schedule – are indicative of a resounding success of this project," emphasized Uwe Gfrörer. BHS is also delighted with the successful collaboration: "The plant has been continuously running to the complete satisfaction of the operator ever since," concluded Gerd Schuler.
The Netherlands is protected from flooding by a 32 km long dam: the Afsluitsdijk. This impressive structure – the total area of which is around 700,000 square meters – is in the process of being completely modernized and expanded. For this purpose, innovative concrete blocks from Holcim Coastal B.V. are being used. To ensure the blocks are of an equally high quality, they opted for strong partners in terms of mixing technology and plant engineering: BHS-Sonthofen and Loke BV. BHS is delivering the mixer for the expansion of the production facility in Alphen aan den Rijn, where the concrete for the project is to be mixed. Loke BV took over the construction of the plant.
The Afsluitsdijk dam, located between the Wadden Sea and the Ijsselmeer, has protected large parts of the Netherlands from flooding since 1932. Due to constant environmental influences, the structure is now in need of renovation and modernization. The dam should become more stable with the help of innovative concrete blocks introduced over the course of a multi-year project. This will be achieved through the use of “Levvel-blocs” specially developed by Dutch project company Levvel for the lower embankment and special basalt Quattroblocks from Holcim Coastal B.V. for the upper embankment.
Innovative concrete elements to help deal with the highest degree of stress
Dutch company Holcim Coastal B.V. specializes in hydraulic engineering and coastal protection. Jean-Pierre Quartaert, Managing Director of Holcim Coastal B.V., explains the procedure for selecting suitable concrete elements for this project and similar ones: “Our goal was to combine a high degree of stability with durability and using the smallest amount of materials possible. That’s why our Quattroblock – introduced in April 2018 – consists of four interconnected columns. It is important to test these kinds of new designs extensively in advance.” That is why the Quattroblocks were exposed to simulated currents and shafts in the Delta Flume test facility in Delft in a water basin 300 meters long, 5 meters wide and nearly 10 meters deep. The results were impressive: compared to their predecessors (the pure concrete blocks), the Quattroblocks are 40 percent more stable.
“We now require the appropriate technology to produce the concrete elements,” explains project manager Jörg Switala. “In view of the large quantity and demanding end application, the highest degree of operational reliability and perfect level of homogeneity were particularly important to us.” The decision fell to BHS-Sonthofen – the experts in mixing technology – who are very familiar with large-scale, demanding projects. The Dutch Holcim factory in Alphen aan den Rijn – where the elements are manufactured and shipped – required two mixers in order to produce a daily throughput of 520 m³ for the start of the project in 2019. The company is to supply concrete for a total of 700,000 square meters of dam area until the end of the project in 2023.
BHS technology guarantees the necessary homogeneity
André Däschlein, Sales Director Mixing and Crushing Technology at BHS, recommended the use of the industry standard twin-shaft batch mixer of type DKX for the task at hand. “Decades of high-level expertise in the concrete sector have enabled us to draw on experience from a great number of similar projects,” says Däschlein. “This made us very confident that the twin-shaft batch mixer would provide the necessary high level of homogeneity that the client requested.”
The secret behind the intensive material exchange that can be achieved in a very short amount of time is the three-dimensional mixing principle: two shafts generate circular movements with a turbulent overlapping area, so that the energy introduced is optimally used for an even distribution of the mix. Therefore, the high level of mixture homogeneity is the perfect solution to needing to use the lowest amount of energy possible – a decisive factor for a project of this size. This also results in a high level of operational reliability and machine availability, which are absolutely necessary given the expected high capacity utilization.
The BHS mixer: ideal for concrete blocks
BHS-Sonthofen’s ability to provide consultation regarding concrete elements is based on many years of experience in the industry. “Customers continue to be surprised that the BHS mixer is also suitable for concrete products and blocks that come with the highest demands on mixture homogeneity,” says Däschlein. “Our DKX series includes a special mixer configuration for concrete blocks, which is already being used by numerous companies with great success.” The adjusted speed, exact moisture measurement and water dosage makes the twin-shaft batch mixer the perfect choice also for very demanding products such as concrete for surface layers.
The BHS mixer was used for concrete blocks in the Netherlands even before the start of the dam renovation project: Excluton, the operator of the largest concrete block factory in Europe, has its headquarters in the Netherlands and uses the twin-shaft batch mixer from BHS to produce surface layer concrete and core concrete. Working together with Dutch company Loke BV, BHS delivered DKX mixers to concrete mixing plants in 2014 that still to this day produce top-quality concrete 22 hours a day, six days a week without interruption. Holcim Project Manager Switala feels empowered in his decision making thanks to the success of these projects: “In terms of mixing technology, we have found a strong partner in BHS-Sonthofen – for a project of this size, it is extremely important to use proven, high-quality technology.”
Mixing concrete for more than 1100 windmills of Europe’s biggest wind farm is no small task. Which is why Tecwill Oy, a Finnish expert for concrete batching plants, puts his trust in a twin-shaft batch mixer from BHS-Sonthofen. The mixer produces four cubic meters 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 windmills, with 440 more windmills to follow. In total, the Markbygden Wind Farm will consist of more than 1100 windmills which produce up to 4000 Megawatt of green energy. The bases of the windmills consist of about 600 cubic meters 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 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 four cubic meters compacted concrete per batch.
BHS-Sonthofen – a 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.”
This is not the first cooperation between Tecwill and BHS. Since thirty years, the Finnish specialist 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. The reputation of the long-established company has even convinced Tecwill’s clients. “Many of the companies we work with specifically ask for a twin-shaft batch mixer made by BHS-Sonthofen,” explains Mika 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.”
The mixer used for building the Markbygden wind farm is able to produce about 120 cubic meters of regular concrete or 90 cubic meters 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. “Theoretically, if run 24 hours a day, the plant could even mix concrete for up to three windmill bases – for the mixer this would not be a problem,” Mika Silvennoinen concludes.
Sand manufacturer Kasprs Build Mate inaugurated a new plant for processing off-spec particles in Pune, India, in mid-2019. The centerpiece of the plant is the rotor impact mill from BHS-Sonthofen, which, in contrast to conventional VSI rotor crushers, even further reduces fine grain sizes. Kasprs can thus make use of off-spec material of other companies to produce high-quality Plaster sand and Dry Mortar Sand for the construction industry. High economic efficiency goes hand in hand with the conservation of natural sand reserves.
Kasprs Build Mate Private Limited is a company based in Pune in the Indian state of Maharashtra. The range of products includes sand, mortar, and concrete as well as bricks for the steadily growing Indian construction industry. Major projects in the mega-cities also require sand of the highest quality. Unregulated mining of this basic raw material leads to numerous environmental problems such as erosion, water pollution, and increased risk of flooding and drought. It is therefore essential to use this resource as efficiently as possible.
Maximizing the yield from rock with BHS-Sonthofen
Sand production using conventional VSI rotor crushers, as they are often used in India, produces a large volume of off-spec particles, which are 10 to 15 mm in size and remain in the circuit without being crushed any further. These off-spec particles can account for up to 35 percent of the total volume. As they are of no more use to the sand manufacturers, they are backfilled. Kasprs Build Mate was looking for a way to turn this surplus material into high-quality sand as well.
Himanshu Mavadiya, Production Applications Manager at BHS India, identified the RPM 1513 rotor impact mill as the perfect tool for this task: “Our RPM 1513 delivers a targeted and very high crushing ratio, which has a consistent grading curve over the entire tool lifetime. It is therefore able to produce sand of the highest quality with an excellent particle shape from the surplus material of conventional rotor crushers.” The producer benefits considerably from this and, in addition, every ton of sand that can be produced from off-spec particles slows down the depletion of natural sand deposits.
Preliminary trials in the test center result in a best-of-breed solution
BHS-Sonthofen has a modern test center where the material to be processed can be tested in advance in various machines. “In this particular case, we are dealing with basalt – a magmatic rock that presents some challenges,” says Mavadiya. “The BHS experts in Germany were able to carry out tests using a rock sample, allowing them to select the ideal machine and determine the best settings, too.” The customer did not want to leave anything to chance in this project and therefore inspected the machine at the German production site. The key goal was not only to find the right technology for the application, but also one that stood out from competing suppliers in the Indian region in terms of quality.
The selected RPM 1513 rotor impact mill fulfilled all expectations right from the start. In total, several hundred thousand tons of high-quality sand have already been produced. Anup Karwa, Project Manager at Kasprs Build Mate, is satisfied: “For our company, efficient value creation and thus resource savings is an enormously important decision factor when it comes to choosing a new technology. BHS-Sonthofen convinced us on site with their modern test center, experienced shredding experts, and robust high-performance machines.”
The “Kasprs Sand” brand
In the meantime, the sand produced by the BHS rotor impact mill has become a brand in its own right. “Customers have taken to calling this high-quality product Kasprs Sand. This name stands for an optimal, homogeneous particle shape. And despite the somewhat higher price, it has become a sought-after construction raw material, especially for ambitious projects,” reports Karwa. In contrast to naturally occurring sand, which often has to be shipped over vast distances and is sometimes of dubious origin, this sand is also a local product: The basalt rock mined in the vicinity of the plant has been made fully usable by BHS technology.
Dragados UK & Ireland, a construction branch of the Spanish ACS Group, is using mixing technology from BHS-Sonthofen to produce concrete in the £350 million expansion of Aberdeen Harbour in Scotland. A total of approximately 9,000 accropodes are manufactured with the concrete and used as the outer armour for the north and south breakwaters. To this end, Industrias Leblan provided Dragados with a mixing unit including a BHS twin-shaft batch mixer.
Aberdeen Harbour is one of the busiest ports in the United Kingdom, serving Scotland’s third largest city and significantly contributing to the local economy. Aberdeen Harbour Board is expanding its facilities in order to enhance the marine support capabilities and transform the port’s ability to accommodate the trend for larger vessels. New facilities and associated infrastructure are currently being built to the south of the existing harbour. Construction began in May 2017 and the project is due for completion in 2021.
To resist the action of waves on breakwaters and coastal structures, Dragados UK, the main contractor for the Aberdeen Harbour Expansion project, produces concrete objects that are named “accropodes”. These building blocks appear like rocks and blend into the surrounding landscapes. Over the entire project period, some 9,000 accropodes are manufactured on a carousel production system. The accropodes are made in three sizes: 8, 12 and 16 m³ – with the 16 m³ mold being the largest to have been produced by an automated factory process.
Dragados expects to have batched 245,000 m³ concrete by the end of the project. For concrete production, Dragados purchased a mixing unit from the Spanish supplier Industrias Leblan including the twin-shaft batch mixer (DKX) from BHS-Sonthofen. According to Dragados, the mixing technology turned out to be the perfect solution for the challenges the company faces. For instance, the concrete needs to reach a hardness of 40 Megapascal (MPa) within a certain time.
The twin-shaft batch mixer of type DKX is the benchmark in mixing technology - it rapidly produces mixtures with consistently high levels of homogeneity and is ideally suited for mixing processes with high output requirements. The three-dimensional mixing concept results in a more intensive exchange of materials and in shorter mixing cycles with reduced energy consumption. This concept has also proven to be superior in the port expansion project. Manfred Immler, Area Sales Manager for West Europe at BHS-Sonthofen, said: “Aberdeen Harbour expansion is an exciting and fascinating project in which all participants have worked closely and well together.”
After winning an international tender, BHS-Sonthofen was commissioned with constructing the largest mixer in the company’s history. An Indian zinc mine operator required a mixer with a very large filling capacity. The proven Combimix system with overflow was custom-built by BHS-Sonthofen in this extraordinary size and shipped off to India. Ease of maintenance, implementation of all customer requirements and a local service office convinced the Indian customer to opt for BHS-Sonthofen.
The largest zinc mine in the world is located in India. And when it comes to total zinc production, India ranks among the top 10. To backfill the mines, the operators require high-quality and robust mixing technology with a very high throughput capacity: Overburden and filter cakes, the by-products of zinc production, need to be mixed to a homogeneous mass free of clumping in order to make the mixture as readily pumpable as possible for backfilling.
An Indian mine operator launched an international tender among mixing technology experts to source new mixers for an upcoming plant conversion. BHS-Sonthofen won the contract due to their high-quality, customizable technology and comprehensive mining expertise, and because the German company also has a dedicated sales and service team in India.
BHS-Sonthofen competently implements demanding customer requirements
The customer’s requirements were very clear: a longer retention time of the material in the mixer and a filling level below the mixing shaft. This means that the mixer required a much larger filling capacity to process the same quantity of mixing material than in the conventional design. Design engineer Sebastian Poppel was responsible for customizing the technology. “These special customer requirements meant that the mixer had to be built for a total capacity of 28,000 liters,” says Poppel, “This made it the largest mixer we’ve ever designed at BHS-Sonthofen.”
The experts at BHS decided that the Combimix system, a twin-shaft mixer of the DKXC series with overflow, would serve as the perfect base technology for the application. According to the customer’s requirements, the filter cake needed to have a long retention time to yield a final mass with maximum homogeneity and as little clumping as possible. In order to optimally meet their customers’ requirements, BHS can draw on a wealth of experience and even carry out extensive tests. “With a throughput of 263 m³/h, we arrived at a retention time of about 137 seconds,” explains Poppel. “During this time, lumps are dissolved to our satisfaction thanks to the high-performance mixing unit.”
A characteristic feature of the twin-shaft mixer from BHS is the three-dimensional mixing method. The turbulent overlap zone of the two mixing circuits generates an intense material exchange, as well as very high relative movement, thus resulting in a highly homogeneous final product.
In addition to the other requirements, the customer also wanted a product that allowed for high-pressure cleaning and delivered easy maintenance access. BHS-Sonthofen was able to meet these specific requirements without any problems. Production of this largest-ever BHS-Sonthofen mixer was completed in August 2019, and the unit was loaded onto a ship bound for India. Installation in the zinc mine took place at the end of the year under the supervision of BHS experts.