As part of an expansion in capacity for the manufacture of a special medical diagnostics powder, a production facility in Northern Europe has been equipped with a milling and filling system. A particular challenge was to deliver a production flow of 5000 kg/h using gravity alone, while occupying a minimum of space.
The special powder for medical diagnostics is an intermediate product for a solution that is used as a contrast medium in the human body. The production steps cover precipitation of the granules in a reactor with subsequent drying, followed by milling and filling of the powder into 900 kg big bags. In many respects, the existing milling and filling equipment no longer satisfied current requirements: on the one hand, it had ceased to be compliant with the strict GMP (Good Manufacturing Practice) criteria and on the other hand, the filling sequence with a non-closed system was linked to considerable dust formation. Thanks to its convincing proposal, Frewitt won the contract to deliver a modern installation for the milling and filling process, which was to be housed in a specially designed new building. The DryMilling Division was responsible for the engineering and development of the hammermill; the ProFilling Division supplied the components for the filling process.
A central requirement was product flow solely under gravitational force, with useful height dictated by the new building. A solution with compact dimensions was developed within the context of an engineering project shared between the customer and Frewitt. All components – comprising the emptying station, storage silo, hammermill and filling of the big bags – have been installed in a vertical arrangement with an overall height of only 9.7 m. From the point when the granules are released into the storage silo through to filling the milled powder, the process is completely dust-free and meets GMP and FDA standards. The 900 kg capacity big bags are filled to ±1 kg at a rate of 5000 kg/h.
Heart of the system
The MFH-15 performs a key role in the Frewitt installation. Thanks to this hammermill, it has been possible to meet the customer’s requirements for a compact design and high throughput of up to 5000 kg/h. The high-performance rotor ensures that the product is quickly reduced to the desired dimensions, with minimum grain sizes of less than 0.2 mm. Good accessibility means that the rotor can be reversed without difficulty for milling with the hammers or with the knives. The MFH system has been specially configured for processing hard and crystalline products. Because the rotor is mounted on a single bearing, product heating during the milling process is kept to a minimum. Moreover, a gas-tight seal on the rotor shaft prevents penetration of the milled product into the drive, cools the bearing and keeps the milling area inert.
The MFH-15 hammermill produces an excellent powder quality with maximum efficiency. All components that come into contact with the milled product are in stainless steel or sealed with silicone and Teflon in line with the FDA standard. The mono-bloc design and polished surfaces (Ra # 0.8 µm) make sure that the product can flow without friction throughout the entire milling and filling process. Thanks to the closed system, a clean process is guaranteed throughout, with no contamination of the milled product. Accumulation of the product is effectively avoided, enabling quick and easy cleaning as well as stable production.
In the interests of rapid implementation, the engineering and assembly phases of the project were split into four main groups: big bag emptying station, storage silo, hammermill with dosing unit, and filling station with weighing scales and operator terminal. Thanks to meticulous planning and close cooperation between the customer and engineers from Frewitt, it was possible to commission the plant successfully only a short time after awarding the contract.
More information on the hammer mill
Overview over filling systems
Trade fair Powtech 2005