Ajax Improves Coal Flow at Corus Scunthorpe Steelworks

Improving the flow of coal from coal bunkers to charge cars feeding coke ovens at the Corus Construction and Industrial iron and steel works at Appleby, Scunthorpe, is the latest success for Ajax Equipment.

Straddling the Appleby coke ovens, the coal bunkers were built in the 1930s and originally designed to store local coal, but today hold imported coal from Canada and Australia. It is the particularly cohesive properties of the imported coal that creates flow problems, making the material difficult to handle.

In theory these huge bunkers have a potential capacity of 4,000-tonnes, but in reality their true useable capacity is nearer to 1,500 tonnes. This was due to the phenomenon of 'rat holing' where a significant quantity of the contents was effectively trapped around the periphery of the bunker with only the central core of coal directly above the outlets flowing from the bunker into the charge cars. The bunker geometry and construction caused the residue to remain even when the central flowing channel emptied.

To overcome the rat holing effect, Ajax Equipment undertook a detailed review of the bunker design and carried out extensive flow property tests and practical trials. The tests identified that stainless steel inserts could be configured to create a plane flow hopper bottom and spread the flow to previously 'dead' areas of the bunker. Whilst these techniques would improve flow potential and increase the amount of useable inventory there were awkward installation aspects that needed special consideration and there was a critical need to prevent mass flow fully developing in the structure.

Corus project engineer, Ken Picking said: "We had to strike a fine balance between improving the coal flow by overcoming the rat holing and increasing the operational capacity of the bunkers while at the same time preventing the mass flow which would have put too much strain on the concrete structure supporting the bunkers. Ajax Equipment's vast experience in hopper design and flow inserts has ensured we met our project objectives and gained improvements in coal storage and charge car productivity."

Original article from AJAX Newsletter Issue 3

Rat holes in the bunker BEFORE fitting inserts

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