Modern processes often use high potency APIs and other ingredients, which are potentially dangerous if mishandled – this is a particular concern during milling, a process which is notorious for generating dust. Hence, in order to protect both the operator and the process environment, it is important to consider various methods which could be used to help minimise this problem and achieve a dust free milling process.
There are a number of ways to contain dust during cone milling, this article shall focus primarily on three methods; in-line vacuum transfer, container-to-container milling and milling inside an isolator. All three techniques offer an efficient and effective way to achieve dust free milling.
In-line Vacuum Transfer
Feeding and discharging from a cone mill using a vacuum is a particularly effective method for achieving dust free milling. This process not only contains the dust, but also automates the process and minimises waste – helping customers make efficiency savings.
Using an in-line vacuum transfer system (such as the Hanningfield Uni-Vac), material is automatically fed into the inlet chute, and is also automatically drawn from the outlet of the mill. This process ensures that from pick-up to discharge, the system is fully enclosed, preventing the escape of dust.
Container-to-Container Milling
This solution uses the principle of gravity to feed product through the mill. By positioning a bin above the mill, and another bin below the mill, product is released from the top IBC, milled, and then passes directly into the bottom IBC.
This creates a totally contained, in-line solution for milling. Not only does this contain the product during the milling phase, but this is also a simple and effective method for transferring product from bin-to-bin, and cone milling the product en-route.
Isolator Milling
One suggested method for the containment of such fine powder during milling, is the use of an isolator or ‘glove-box’ to ensure all excess material remains contained, ensuring the fine dust particles are not exposed to either atmosphere or operator.
Cone mill integration within the isolator is performed by means of through the wall fixing flange. This fixing flange and particular configuration of the cone mill allow for a physical division of the cone mill head by the technical area that is left outside the isolator. Thanks to this special configuration all cone mill cleaning operations are performed within the isolator by means of gloves or half-suit, reducing any risk of exposure for the operator and avoiding any transport to cleaning room.
Another benefit of isolator milling is for achieving a zoned area such as ATEX. The isolator itself creates an ATEX environment for milling, ensuring the entire process environment (including motors and controls) do not need to be changed to comply with the necessary requirements. Learn more about milling in an isolator here.
Conclusions
In a modern process, containing dust is extremely important. This can be easily achieved during the cone milling stage, simply by employing one of the methods listed above. Each solution will be more or less suited to any particular application.
Get in Touch
If you would like to speak to one of our experts regarding our Isolator Conical Mills or you would like to discuss your dust-free milling application, send us a message using our Contact Form or call us on +44 (0)1702 549 777.
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