Industry Blog

Achieving a Dust-Free Milling Process

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.

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.

For more information on how to contain dust during processing, please just contact us.

High Containment Transfer Systems

The need for containment is greater than ever, given the increasing potency of processing ingredients and API’s.

Improving containment is often the main driver for specifying new process equipment in the pharmaceutical and associated industries. Current expectations of levels of containment often far exceed the capabilities of equipment designed and manufactured only a few years ago. There are many ways of improving process containment.

There are a number of reliable high integrity methods for ensuring containment during transfer;


Gravity Transfer using a Hoist

Gravity Transfer typically uses a combination of gravity feed and flexible silicone sealing interfaces. Lift systems are often a main component in gravity transfer for accurate docking of process equipment such as IBC’s and valves. High containment lift systems use intelligent positioning sensors to ensure outlets and inlets are precisely aligned, allowing the fast and accurate transfer of powders, granules and liquids etc.

‘Failsafe’ is another important feature of a lift system which is to be used in a high containment application. The security offered by the ‘failsafe’ feature ensures that even in the event of a machine breakdown, the two ports will remained docked, and most importantly, the material will remain contained and uncontaminated.


Flexible Silicone Connections

The connections between each element of the transfer process are the weakest links in the transfer chain. To ensure containment is not compromised at these connecting points, silicone dust caps and flexible sleeves can often be used. These elements provide simple cost effective containment which is very adaptable and easily cleaned.

Another benefit is that some of these components can be translucent of clear, allowing a visual indication of the process condition. Typically these transfer connections take the form of silicone caps and sleeves. Generally the connection parts are moulded in standard sizes so this should be taken into consideration when designing and specify new process equipment installations.


Split Butterfly Valves

The integration of a split butterfly or ‘High Containment Valve’ between the inlet and outlet of two process components creates a fully contained method of product transfer, with virtually zero exposure to either the operator or the process environment. This is extremely important when handling potentially hazardous material or material that cannot be exposed to ambient air. Total sealing during emptying and filling operations can be easily achieved with the split valve system and fully automated valves can be specified which allow ease of operation in difficult to access locations such as containment isolators.

The split valve system comprises of an ‘active’ and ‘passive’ half. The active half of the valve has most of the moving parts and is usually static. The passive half is often installed on the moving part of the valve interface any in some cases a large number of passive valves and be docked into the same active half. The split butterfly valve provides the most effective high integrity method of contained transfer.


Vacuum Transfer

Another commonly used method of containment is vacuum or ‘pneumatic’ transfer, which uses contained pipe-work and hoppers to transfer material. The main advantages of vacuum conveying are that it is very flexible if needed to cope with a variety of process duties, has very few moving parts and is easily cleaned. The most common form of vacuum transfer is termed as ‘lean-phase’. The lean-phase method of vacuum transfer uses entrained air to create an air-flow for efficient material conveying.

Vacuum transfer can be used over considerably long distances and has the additional benefit of being very low maintenance. Conveying of materials by vacuum is a well established process in the pharmaceutical industry and rarely has any detrimental effect on the product integrity. There are many different configurations used in vacuum conveying allowing automated material pick-up, level control, multiple integrated systems and other special design to deal with variable material properties.

Containment Q&A

Question and Answer with Colin Ellis (Managing Director, Hanningfield)


As the issue of containment becomes evermore topical, Hanningfield’s Managing Director, Colin Ellis, answers some questions about containment, offering advice, opinion and dispelling a few myths.

 

Q. Firstly, what do you mean by containment?
A.

Containment is the prevention of contamination by means of a barrier. This can mean the contamination of the product, the operator or the environment. Generally people think of containment as stopping contaminants getting out, but it is also equally about stopping contaminants getting in; this is why the barrier is important.

The difficult balance to address is how to create a barrier for containment without affecting ease of operation. It is this problem which challenges manufacturers and equipment suppliers alike.

 

Q. Why has the issue of containment become so pertinent recently?
A.

The issue of containment has always been relevant. However, I think it is fair to say that it has become a particularly hot topic over the past few years - no doubt that ever improving health and safety standards have played a huge part in this. Also manufacturers, particularly in the pharmaceutical industry, are using ever more potent ingredients; the potential dangers associated with these make it is essential that they are properly handled and contained.

It is important to remember that containment is not just a ‘buzzword’, rather it is a method of keeping processes safe and secure.

 

Q. Which industries does containment apply to?
A.

With increasingly strict standards in relation to the exposure of operators to hazardous materials, it means that a broad spectrum of industries, such as pharmaceutical, food, minerals, chemicals and ceramics are all subject to strict legislation for containment.

In fact any industry involved in powder processing or any activity which produces dust should be making every effort to reduce employee exposure to health hazards and explosion risk.

 

Q. What are major benefits of containment?
A.

The importance of powder containment needs to be fully understood to reduce operational injuries and industrial claims, as well as improving general hygiene standards and issues affecting the welfare of employees. Although welfare is a major factor in controlling exposure to hazards other benefits are reduced waste, less likelihood of a dust explosion and an improved working environment.

 

Q. Are there any simple ways to comply with containment?
A.

Most dust or excess powder material is created during transfer or transportation within the process area. Processes such scooping, pouring and tipping all create dust problems. If these actions are eliminated or controlled the problem is easily solved.

The most cost effective containment solution is to use silicone sleeves and seals for containing dust during transfer processes. Scooping, tipping or pouring can all be replaced by using vacuum transfer systems which keeps material contained during any transfer process.

 

Q. Is containment a wise investment?
A.

Despite the inevitable costs associated with improving containment, the financial investment can be soon recaptured through improved efficiency. Reduction in waste by keeping products where they should be and in the case of vacuum conveying reduced manpower are obvious areas of a definite return on investment.

Improved safety also has an impact on productivity, which provides the additional benefit of an improved employee/employer relationship. To sum up it is quite clear that apart from certain legal requirements to ensure adequate operator safety there are potential longer term savings to be made in improving efficiency through a carefully planned contained process design.

 

To learn more about Hanningfield’s containment solutions, please click the link below:


Colin Ellis

About the Author

Colin Ellis is the Managing Director of Hanningfield. He has over 30 years experience in the process industries.

Prior to founding Hanningfield in 1987, Colin worked as an engineer for Smith and Nephew, May and Baker and GlaxoSmithKline.

E-Mail: colin@hanningfield.com

Dust Containment - Make Your Process Safe

The containment of dust during pharmaceutical, food and chemical processing is vital.

Any excess dust which is not properly captured can enter the working environment and compromise the safety of workers.  Airborne dust particles can be extremely hazarous, hence the containment of this becomes vital.  The Uni-Dust cyclone helps contain this problem, whilst making product reintroduction or batch loss reconciliation possible.

For more information on the issue of dust containment, please click here.

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