Equipment & Technology

Mideco helps control the flow

Clouds of dust that escape during the material handling process pose extreme risk. To keep workers and the environment safe, Mideco has designed several solutions that harness engineering principles.

When is the hopper full? This is a question that Melton White, managing director of industrial dust collection specialists Mideco, has asked dozens of senior engineers.

And the answer always manages to surprise those engineers.

“A hopper is always full,” White told ABHR “Even when it’s empty, it’s full of air.

“When product goes into the hopper, the air is pushed out as the material goes in. Dust is liberated when this happens, which is the first step to understanding how to best manage it.

“You study the air, why and how it is being liberated and at what speed. Once you control these things, you have control of the dust.”

Mideco aims to give its clients a lightbulb moment and change the way they think about dust. When its team starts working with a client, a common request will be to collect the dust.

Instead, Mideco’s specialists will ask if the client wants to collect the dust or wants to stop fugitive dust. For most customers, the dust has a weight that is part of the main product’s value, which is just being blown away or collected and disposed of. 

White said if Mideco can manage the fugitive dust – it can remain part of the process, maintaining value to the operation.

“Our Burnley Baffles are a great example of how we can manage fugitive dust instead of merely collecting it,” he said.

When applied alone to a hopper, Burnley Baffles can eliminate up to 80 per cent of the dust. They can work in conjunction with an additional dust collector attached directly to a hopper to manage the rest.

The Baffles use simple, yet highly effective, principles of gravity and air movement. They consist of a set of modules that fill the open inlet face of a hopper, with each module containing a set of blades that pivot to allow the material to flow into the hopper.

Because the blades are heavier than air this process strips the air from travelling with the grain or ore as it falls into the hopper, due to the air pressure on all sides of the baffles being all but constant. As the air is not heavy enough to open the blades, only the product enters the hopper, while the dust travels with the product.  This means only the product enters the hopper.

The product still displaces the air in the hopper, and it still must escape one way or another. The baffles put a mechanical resistance on this displaced air flow, which results in the air being dispersed across the whole hopper surface. This means the air travels slower and doesn’t have the energy to pick up the dust.  These two principles eliminate the 80 per cent.

White said another fact to remember when it comes to managing airflow is that there is no such thing as suction, or at least suction can’t be directed.

“If you put a straw in your mouth and blow through it onto your finger, you will feel your breath,” he said.  “If you instead suck air in, you won’t feel much at all, if anything.”

That’s because when the air is leaving the straw, it’s moving in one direction towards your finger. 

“When you suck, air is pushing into the below atmospheric (negative) pressure area you are creating from every direction equally.” 

When total dust management is required, the baffles both resist atmosphere’s ability to push into the negative pressure area equally and resist the air in the hoppers ability to flow up and out. The introduction of a controlled path of least resistance for the air in the hopper, gives you control of the dust. This can be created by means of a small fan and dust collector. Then the dust is stripped from the air before it is released back to atmosphere.  Intelligent dust collector connections can mean the dust never leaves the hopper environment. 

White said every Burnley Baffle application starts off with a question: what is your actual objective? Every project is different and can require a unique approach. 

“A couple of years ago, we worked with an iron ore exporter in Whyalla (South Australia). Our objective there was to get the air in a shed clean enough so that front end loaders could get back into the shed quickly to feed the ship loading conveyors,” White said.

“By understanding that the objective was not to collect the dust, but manage what it was doing to the rest of the process, we were able to help them improve their operation.”

Going into 2023, Mideco is looking to move further into the silica space. They also want to focus more heavily on bulk handling applications.  To that end they are both culling some offerings and developing new products in that direction.

White said one of the key lessons from this year was to push everything.

“That means you need to push your ideas forward – learn new production techniques, look at how your product line flows, how you handle spare parts, and more,” he said. 

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