FSP Foundry Sand Processing GmbH offers a patented wet regeneration process
Many foundries are currently grappling with issues such as resource scarcity, rising energy prices and environmental regulations, particularly with regard to the regeneration of spent sand. FSP Foundry Sand Processing manufactures sand processing plants and offers an operator model as a service, enabling foundries to regenerate spent sand in a cost- and resource-efficient manner. The company also offers a globally patented wet regeneration process for water-glass-bonded spent sand, which has been successfully used at the pilot plant at its Stuttgart site since 2022. Furthermore, a pilot plant for mechanical-thermal sand regeneration has been in operation since May 2024.
Expansion of the pilot plant at the Stuttgart site
The sustainability and significant energy-saving potential of the wet regeneration plant are particularly noteworthy, as FSP Managing Director Stefan Zimmermann (Dipl. Oec.) emphasised at the company’s first in-house exhibition. “Thanks to our patented drying process and the integrated water treatment system, 98 per cent of the key components are recycled! Water is treated, distilled and returned to the washing process.
Only 12 litres of fresh water per tonne of material need to be replenished. The typically high energy input associated with conventional drum drying is offset in our plant by condensation recovery.
This results in a reduction in energy consumption of up to 60 per cent.” The current throughput of the wet regeneration plant is 1 t of sand per hour. Following the expansion of the plant, this will increase to 3 t of sand per hour. The expansion of the existing pilot plant for wet regeneration is planned for a well-known car manufacturer.
A regeneration rate of 85% and lower energy consumption
A major advantage of wet regeneration is that, thanks to the patented process, up to 100 per cent of the sand is returned to the foundry’s material cycle as regenerated material. Equally impressive results are achieved with mechanical-thermal regeneration.
“We achieve a regeneration rate of 85 per cent and energy consumption of less than 10 kW/h per unit of material. We are the first company in the world to offer a wet regeneration process for water-glass-bonded spent sand,” said Stefan Zimmermann when asked how FSP Foundry Sand Processing differs from other sand processing providers.
“We are the only company in Europe to offer the regeneration of spent sand as a service. This not only saves foundries the cost of purchasing new sand; the new operator model also significantly reduces their investment, energy and labour costs. Furthermore, by outsourcing this process, foundries are making a significant contribution to the implementation of the circular economy!”
The service model is simple: FSP operates regeneration plants near foundry sites, collects the spent sand from the foundries, regenerates it and returns the sand to its customers. The process technology used ensures that there is no mixing of the regenerated sand and that each customer receives the regenerated sand made from their own used sand.
“Not only is the sand reused time and again in the casting process, but energy, water and process air also circulate in a continuous cycle throughout the recycling process. And last but not least, the processing of the sand at FSP is largely CO₂-neutral.”
s planning to build two to three further sites
In future, FSP Foundry Sand Processing aims to open two to three further sites, each of which will supply other foundries within a radius of 200 to 300 km from its respective location. Each of these will have a capacity of around 180,000 to 200,000 tonnes of spent sand per year. Stefan Zimmermann is considering the Ruhr region and the new federal states as potential future locations. “The aim is to establish and expand our service model,” says Zimmermann.
’s pilot plant for mechanical-thermal regenerationand wet-regeneration
In addition to the pilot plant for wet regeneration, a further pilot plant for mechanical-thermal regeneration with a capacity of around 1 t/h has been available to customers since May 2024. Furthermore, FSP GmbH plans to install a mechanical-thermal plant with a throughput of 6 t/h – equivalent to around 70,000 to 75,000 t/a – at its headquarters in Stuttgart in the course of this year. The plant will be ready for delivery in early 2025 and will primarily supply foundries in the greater Stuttgart area and the rest of Baden-Württemberg. The cooperation partner for plant construction is Dürmeier GmbH from Vaihingen.
Information on Regeneration of moulding sandsn
When regenerating inorganically-bonded moulding sands, washing is the gentlest method, as there is no direct mechanical impact on the sand grains. This means no additional dust is generated, and all common water-glass-bound spent sands, as well as special sands from 3D printing, can be fully recycled. The process enables up to 98 per cent of adhering residues to be washed off the spent sand. The process water required for washing is treated and kept in a closed-loop system. The waste generated in the process is disposed of using a certified method. In the patented drying system, moisture is removed from the sand in an energy-efficient manner through condensation.
FSP is also setting new standards with its mechanical-thermal regeneration process. The process can be used for both bentonite-bonded green sand and organically-bonded core sand (cold box, hot box, shell sand, furan). Compared with conventional methods of mechanical or purely thermal regeneration, this process technology reduces dust levels to a minimum.
Thermal-mechanical regeneration is characterised by the high efficiency of its three-stage system. Following pre-treatment of the spent sand, the sand is fed, in a dry and free-flowing state, to the first – mechanical – stage, where the binder is removed by sand grain rubbing against sand grain.
In the second step, the sand is fed into the thermal stage. In a sand bed, gas and air mix, causing fluidisation, and the organic binder as well as the fine particles are burnt off. Through the quartz jump effect, any remaining binder residues are dislodged from the natural depressions in the sand grains or even literally blasted off. In the third stage, which is also mechanical, the final residues are rubbed off the grains; this stage operates in the same way as stage one.
From May 2024, both pilot plants will be available to foundries. They can be used to test and analyse inorganic or organically bound sands, or even mixed sands, for their regenerability. FSP offers interested customers a range of different tests – from a simple test series involving up to 1 t of sand through to a complete run-in process, including the determination of the optimal ratio of regenerated sand to new sand in core production. Once the tests are complete, customers receive the regenerated sand, dust and waste back, packed in big bags. This enables them to draw conclusions about the composition of the regenerated sand, for example regarding the ratio of regenerated sand to fine particles and residual materials.
Information about FSP GmbH
FSP Foundry Sand Processing GmbH, founded in Stuttgart in May 2022, develops and markets systems and solutions for the regeneration and processing of bulk materials. This is based on decades of experience in the recycling of raw materials and the mechanical-thermal or wet regeneration of used foundry sand.
The founding partners are Heinrich Feess GmbH & Co. KG in Kirchheim/Teck and DEANTEC GmbH in Kirchhundem. Feess, which was awarded the Federal Environmental Prize in 2016, contributes its expertise in the recycling of mineral waste, whilst DEANTEC brings its experience with its unique, patented wet regeneration and drying process – a plant technology that uses exclusively renewable energy in the processing of spent foundry sand.
FSP GmbH offers customers a complete, virtually CO₂-neutral process chain for sand processing. The regenerated material replaces up to 85 per cent of virgin sand in the case of organically bound sands and 95 per cent in the case of inorganically bound sands. FSP GmbH makes a significant, measurable contribution to resource conservation and sustainable production.