BHS-Sonthofen has supplied three larger than average indexing belt filters for the production of hydrofluoric acid. The key requirement for the design of the belt filters was particularly high chemical resistance given the strong acidic product attributes of the source material. BHS employed acid-resistant metallic materials and special plastics which offer maximum safety combined with high product quality. The plant has been in operation since the end of 2021.
BUSS-ChemTech in Pratteln, Switzerland, is internationally known as a supplier of customized and innovative process technologies for the chemical and aluminum industries. The company supports customers worldwide with its holistic solutions for chemical reaction processes, for example in the production of halogen-containing basic chemicals such as hydrofluoric acid, aluminum fluoride, phosgene, and their by-products.
Recently, BUSS delivered the full process solution and the appropriate key-equipment for a project involving the production of hydrofluoric acid. In this case, a new, more environmentally friendly technology was used that converts fluorosilicic acid into silicon dioxide and valuable hydrofluoric acid. The latter can be further processed for profit, thus eliminating the need for costly neutralization and disposal.
Indexing belt filter enables maximum yield
To get this innovative project moving, BUSS relies on filtration technology from BHS-Sonthofen Process Technology. For the conversion process, the BHS experts provided the indexing belt filter of type BF 300, a continuously operating, horizontal vacuum filter. “With a size of 4.5 x 23.5 m and 58.5 m2 of active filter surface, the filters hold an above-average volume,” explains Simone Ahlert, the responsible project manager at BHS-Sonthofen. Due to the highly corrosive nature of the acid, BHS used particularly acid-resistant metallic materials and special plastics during construction – for instance, for the vacuum tray and the feeding equipment.
Three-stage counter-current washing ensures high product quality
At the beginning of the conversion process, the toxic tetrafluorosilane is dissolved in water and initially reacts to form fluorosilicic acid and sicilicium dioxide. The sicilicium dioxide is precipitated in the reactor and carefully and safely filtered off in the BHS filter subsequently. During this process step, a three-stage counter-current washing system ensures high quality and maximum yield. The now pure fluorosilicic acid serves as the base material for the final product requested from the customer - the hydrofluoric acid. The filter cake on the belt can be further treated in separate processes.
Efficient filtration technology is crucial for this new type of process, and the solution from BHS-Sonthofen has convinced BUSS. The plant went into operation at the end of 2021.
Sonthofen, Germany, 22 March 2022. BHS-Sonthofen closed the 2021 financial year with a record number of incoming orders in the Process Technology division. Despite the pandemic, the company saw incoming orders in this business unit increase by 26 percent year-on-year. The process technology experts are optimistic about 2022, as this year, BHS-Sonthofen Process Technology is introducing new, digital features for its rotary pressure filter. Another milestone will arrive in the form of modularized, standardized product range for filters, mixers and dryers.
It has been one year since the BHS-Sonthofen Group repositioned itself with its Building Material Machinery, Recycling & Environment and Process Technology business units. As of 1 January 2021, its process technology expertise has been bundled under the BHS-Sonthofen Process Technology GmbH & Co. KG name. In its first financial year, the newly founded company recorded incoming orders of just under €100 million.
“Despite the international restrictions and uncertainties caused by the pandemic, we exceeded expectations for 2021,” says Volker Spies, Managing Director of BHS-Sonthofen Process Technology, speaking about the very high number of orders. “We see this success as confirmation of our strategic direction.” In the field of process technology, BHS-Sonthofen primarily serves customers from the chemical, pharmaceutical and food industries. BHS is constantly developing its product portfolio so it can offer them the process technology solutions they need, when they need them. 2022 will also see the company present a series of new products.
Comprehensive process monitoring with advanced rotary pressure filter
These include modifications to the proven rotary pressure filter of type RPF that enable comprehensive inline process monitoring. BHS has revised the continuously operating filtration machine in terms of efficiency and operation, thus making it easier to integrate into the digital processes at the user’s site
A continuous cake thickness measurement allows the filling level in the filtration cells to be recorded during operation. The process parameters are continuously transmitted to a higher-level control system as part of this. If there are fluctuations in the product feed, the filter can automatically adjust the speed to ensure the filtration cells are filled to the optimum level. The measurement is performed using laser technology, which eliminates the need to calculate the cake thickness using the mass balance of the filter. The user benefits from efficient cake washing, consistent product quality and a higher throughput. The cake thickness measurement can also be retrofitted to machines that are already in operation.
Customers also have option to add a feature to automatically monitor the amount of wear for the separator elements, providing them with data they can use to schedule maintenance windows for the machine. This can even be used to have spare parts delivered automatically.
Modularized concepts are a success factor
This year, BHS is also expanding its range of modular machine and plant concepts. The company now offers a standardized product range for common application scenarios. Predefined sizes and components enable cost-effective implementation with short delivery times. All of the components in the modular system are matched to each other and can be combined according to the customer’s exact requirements. Customers can already order standard solutions in a modular system for candle filters and dryers that cover a wide range of applications. In addition, BHS’ high level of process technology expertise means it can offer tailored customer solutions to meet special requirements. This system is available at all BHS locations worldwide.
Integrated filtration and drying systems increase added value
BHS’ broad portfolio of various filtration systems, horizontal and vertical mixing systems and horizontal and vertical drying systems means the process engineering steps of filtration, drying and cooling can be chained together to form compact and optimized systems. These turnkey “package units” – including control, installation and commissioning – can be delivered worldwide via the System Engineering department. In this way, BHS stays true to its mission of “Transforming materials into value” in every area – for the benefit of the customer.
BHS-Sonthofen has supplied two different technologies to assist an innovative recycling process in waste incineration: Since 2021, a rubber belt filter specially suited to the requirements of the new process and a belt filter have ensured fly ash at the Danish power plant operator Vestforbraending is treated efficiently. This brings two benefits: Recyclable materials can now be recovered from the ash and the ash previously declared as hazardous waste can be disposed of as normal waste. Extensive preliminary filtration tests on a laboratory scale were performed before the order was placed to obtain an optimum process result immediately upon commissioning.
The EU wants at least 50 percent of household waste to be recycled and the rest to be used as a source of energy in waste incineration plants. However, the operators of these plants face a number of challenges along the way. Waste incineration produces ash contaminated with salts and heavy metals, which is considered hazardous waste and must be disposed of in special landfills. This involves long transport routes and high costs. Vestforbraending developed a new type of fly ash treatment process under the name HALOSEP in cooperation with the Swedish recycling company Stena Recycling. The project, officially called LIFE HALOSEP, is supported by the EU through the LIFE financial instrument – a funding program for environmental protection measures.
Heavy metals and salts can now be recovered from the fly ash. This makes it possible to store the ash residue in normal landfills for non-hazardous waste, unlike the input material. The new process is therefore a win-win in two respects: It makes it possible to market recovered recyclables and reduces disposal costs.
The pilot plant in Copenhagen, equipped with technology from BHS-Sonthofen Process Technology, started operation in 2021. Samuel Moore, project manager at Vestforbraending, is convinced: “BHS-Sonthofen sets itself apart with its special expertise in the field of filtration. Having such a strong process engineering partner is essential for pilot plants in particular.”
Process efficiency thanks to the perfect technology
Treating fly ash produced during waste incineration is a multi-step process. First, it is mixed with the flue gas cleaning washing water, which leads to metals and salts being released from the ash. A BHS belt filter then filters the resulting suspension. After a further wash, the solid that remains is purified ash.
The process water used in the first step is treated further to recover both salts and metals. After the salt water has been separated, a BHS rubber belt filter with continuous vacuum filtration filters the suspension; the metals are left behind as solids. The process water can now be returned to the process. “Salts and heavy metals are highly corrosive. That is why a robust and corrosion-resistant design was crucial for this project,” says Simone Ahlert, Technical Sales Manager at BHS-Sonthofen Process Technology, summarizing the customer’s main requirements. “BHS-Sonthofen has extensive experience with problematic input materials. All of the machines can also be tested in advance with the respective material.”
Preliminary tests provide all the facts
Each process is unique. For that reason, all of the process parameters and design principles used to select the appropriate filter size must be determined on a case-by-case basis. BHS therefore carried out on-site tests on a laboratory scale directly at the customer’s site, using the exact material that will be used in the final process.
“A constant throughput is crucial in a continuous process – thanks to the laboratory tests, we were able to determine the best way to adapt the rubber belt filter used as well as the belt filter to the process in advance. This means it can be integrated into the overall plant much more efficiently, even with completely new processes such as HALOSEP – or related processes such as FLUWA,” says Ahlert, explaining the proven procedure.
15,000 tons of fly ash will be treated at the plant annually. Moore is confident that he will be able to further optimize the process with the help of strong partners such as BHS-Sonthofen. “Up until now, fly ash could only be deposited as hazardous waste in a mine or mountain, which involves long transportation routes. The aim of the HALOSEP process is to reduce the load on the ash so that it can be deposited locally. If we’re successful, we’ll look at the possibility of using the ash as a building material.”
Technology from Germany, made in China – that is BHS-Sonthofen’s approach for supplying the Chinese market. An HTC 4300 stainless-steel mixer was recently shipped from the BHS factory in Tianjin. The customer – a plastics manufacturer in southern China – is already using the mixer after a five-month delivery period.
“Our site in Shanghai and production facility in Tianjin have allowed us to establish a strong footing in these locations. This, in turn, allows us to provide our customers with local support and achieve short delivery times,” says Volker Spies, Managing Director at BHS-Sonthofen Process Technology GmbH & Co. KG.
BHS-Sonthofen has equipped its production facility in Tianjin with state-of-the-art technology for the production of its stainless-steel machines. Integrating key components from Germany made with German engineering expertise allows BHS to provide its customers with high-quality machines within reasonable delivery times. In doing so, the company places a strong emphasis on quality assurance processes. In order to live up to its promise of quality and meet the high demands of the users, BHS has also fully implemented the proven processes it uses in its German manufacturing facilities at its location in China.
The recently shipped horizontal mixer has a capacity of more than 10 tons per hour and is being used to mix nylon with the master batch as well as solid and liquid additives. The customer frequently changes their formulas, so supplying machines that are easy to clean was a key argument when it came to placing the order. The large, easily accessible cleaning doors make this possible. The customer was also impressed by BHS-Sonthofen’s local service concept. Local, qualified service engineers at BHS-Sonthofen Process Solutions Co., Ltd. in Shanghai are on hand to ensure the customer facilities in China receive fast, expert support. “This tried-and-tested concept speaks for itself,” Spies emphasizes. “We have even bigger follow-up orders already in production, such as from the pharmaceutical industry in China.”
In the spring of this year, BHS-Sonthofen supplied Amino GmbH with two identical pharmaceutical-grade conical dryers for drying various amino acids. Amino is using these dryers in their new production facility in semi-continuous operation as part of the process of expanding its production capacity. What makes these dryers so special? The dryers are alternately filled under negative pressure during the continuous drying process.
What appeals to customers from the medical and pharmaceutical industry the most about Amino, a company that is headquartered in the Lower Saxon town of Frellstedt, is its use of amino acids that are naturally sourced and processed with the utmost quality in mind. The company has been working together with BHS-Sonthofen for some time now and uses several of its machines for filtration and drying. In an effort to expand its production capacity, Amino opted for a completely new production line consisting of two dryers of type HVW-VT 8500. The GMP (Good Manufacturing Practice) pharmaceutical-grade machines give companies in the pharmaceutical industry the advantage of an extraordinarily high capacity.
Amino project manager Gerrit Dierking attests to the machine’s seamless installation: “It was quite a challenge to install the dryers, but the process was made easy thanks to the help of the expert technical team at BHS and everything was performed to our complete satisfaction.” A heavy-duty gantry beam brought the machines through the building sideward, where they were then integrated into the new line.
Pneumatic infeed of the dryers
The structure of amino acids makes them particularly sensitive to temperature, which means it is essential that the drying process is a gentle one in order to meet the highest quality requirements. The moist product is pneumatically transported into the first dryer via two peel centrifuges. “The second dryer is filled once the first dryer has reached its maximum fill level. In other words, the dryer is filled alternately and in a vacuum in a sophisticated lock system”, says Martin Specht, Area Sales Manager at BHS-Sonthofen Process Technology GmbH & Co. KG.
The drying process starts while the machine is being filled. Once the dryer is completely full, the inlet valve shuts and the machine reaches full drying capacity. This enables the semi-continuous production of a number of different products within short process times. “Vacuum drying at low temperatures also ensures especially gentle treatment of the product,” says Specht. Costs are reduced significantly by cooling the product at the end of the drying cycle in the same machine. The heating and cooling technology with a primary and secondary circuit is a part of the supplied system. Finally, the amino acids are carefully discharged and packed in big bags ready for distribution.
The innovative shape of the dryer loader in particular significantly reduces the cycle time for a batch. The vacuum, which is already applied during the filling process, causes the water inside to evaporate immediately, increasing process efficiency. Another major advantage for Amino is that the machine requires little maintenance. “We are pleased to have been able to assist Amino with such an innovative process once again after so many years of successful cooperation”, says Specht.
BHS-Sonthofen has delivered to the U.S. a system comprising two indexing belt filters for use in the manufacture of intermediates for a particularly tear-resistant plastic. To meet the high-quality requirements for the industry, BHS designed a cascade reflux wash for treating the filter cake, which ensures reduced water consumption for the necessary retention time. Before delivery, extensive lab and pilot testing was conducted in BHS’s American test center.
In the course of expanding production, the BHS customer needed a solution for solid-liquid separation in the chemical pre-stage for a particular polymer. At the start of the process, chemical reactions provide a material that has to be cleaned of by-products. The filtration of solid particles is particularly important here as impurities have a hugely detrimental effect on the tear resistance of the plastic. Technical construction requirements at the customer’s site posed additional challenges for the BHS process technology experts. A solution that was originally planned, comprising one indexing belt filter with a 12-stage counterflow wash, could not be realized.
Following process technology advice provided to the customer, the project team opted for two indexing belt filters (BF) – one with four and one with eight wash stations. An indexing belt filter is a horizontal, continuously operating vacuum filter, which enables uniform suspension feeding and stands out thanks to its versatility in terms of process technology. The filter cake that forms on the filter cloth can be further processed in a variety of ways by means of various process steps, such as washing out, dry suction or pressing. In the present case, only a dilution wash for the filtration was possible because of the large inner surfaces of the particles. With a continuously operating filter, however, the retention time of the liquid in each wash zone is relatively short. Regular construction of the filter would therefore cause the wash liquid to pass through too quickly.
Multi-stage cascade wash optimizes freshwater consumption
Drawing on experience from other applications, such as cellulose derivatives, BHS therefore built the wash stations in the form of a cascade. Using sieve plates, the wash liquid is distributed uniformly over the entire surface of the filter cake. What’s special here is that the liquid is repeatedly applied at the same point – a so-called re-flux washing. The cascading design allows a self-regulation of the entire washing stage-package. As soon as a certain level is reached in one station, the additional volume is self-fed into the next, lower-level station. This ensures that every particle is washed eight or four times respectively.
“This combination of reflux and counterflow wash on the indexing belt filter enables us to double or triple the retention time of the liquid. Or in other words, for the retention time required here, the consumption of fresh water is reduced considerably compared to centrifuges. The result is a particularly high degree of washing out with efficient use of washing agent,” explains Detlef Steidl, Managing Director, BHS-Sonthofen Process Technology.
BHS-Sonthofen designed and delivered the system, which comprises the two indexing belt filters including separators, as well as measuring and control technology. Delivery was preceded by extensive lab and pilot testing in the U.S. test center, where BHS has expanded its testing capacities for filtration, mixing and drying over the last two years. “In the lab, our work included determining the required fresh water to consumables ratio, which was then reproduced on the pilot filter with multiple wash stages. This enabled us to demonstrate to the customer that the high-quality standards were fully met with this filter solution – making considerable savings on consumables compared to other solutions,” says Steidl. The system was put into service in late 2020.
BHS-Sonthofen is bringing together its collective process expertise in filtration, mixing, drying, granulation, sterilization and reaction in the newly created Process Technology division. As of 1 January 2021, AVA GmbH & Co. KG and the Filtration Technology division have been operating jointly under the BHS-Sonthofen Process Technology GmbH & Co. KG name with headquarters in Sonthofen and a site in Herrsching. Their activities are targeted primarily at the chemical and pharmaceutical industries.
With its acquisition of AVA GmbH & Co. KG in 2018, BHS-Sonthofen expanded its range of solutions and consulting services in and around mixing, drying, granulation, sterilization and reaction. BHS is consolidating its process expertise and portfolio of filtration technology and related products in the newly established BHS-Sonthofen Process Technology GmbH & Co. KG. This marks the final step in the process of integrating AVA into the group.
“We have fully repositioned the company with three business units, Building Materials Machinery, Recycling & Environment, and Process Technology,” reports Dennis Kemmann, CEO of BHS-Sonthofen. “Each of the business units serves specific industries. We work in partnership with customers primarily from the chemical and pharmaceutical industries, but also from the food production and other sectors, to develop process technology solutions.”
BHS-Sonthofen Process Technology provides system solutions as well as individual machines and components. The focus is on process engineering consulting for the customer, drawing on the company’s decades of experience acquired in a large number of different projects. One of its core businesses involves testing customer materials. BHS has recently expanded its testing capacity in target markets like the U.S. in an effort to best serve our customers where they are.
Detlef Steidl, former Senior Sales Director at Filtration Technology, and Volker Spies, former Managing Director at AVA, have been named to serve as the Managing Directors at BHS-Sonthofen Process Technology. The two will continue efforts to develop innovative processes and expand the global presence of the company in the core regions of Europe, Asia and North America.
BHS is able to offer a wide range of technologies which it can draw on to provide the ideal solution for the customer’s specific application. Its portfolio includes mixers for homogenization of materials and solutions for mechanical solid-liquid separation, drying and reaction.
“The new structures give us greater flexibility as a process technology solutions provider, which in turn makes us more competitive on the global marketplace,” Kemmann explains.