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De-bricking a Contaminated Chromium Kiln! - circa 2012!

Look what we've unearthed! Images and a case study from a challenging Kiln De-bricking and decommissioning of a Contaminated Chromium Furnace, Circa 2012!

View of One of the Chromium Kilns
General View of One of the Chromium Kilns

A Blast from the Past!

Regular replacement of Kiln and Furnace Refractory Linings incurs Loss of Production Time and, in the past, prior to the development of Robotic Demolition Procedures, necessitated the use of inefficient, hazardous manual demolition operations

Seven of Gnat's Robots were centre stage in the decommissioning of this major Chromium Chemical Plant, carefully ‘wrecking’ the linings of several vast steel kilns

Hydraulically operated pecker arms - more at home breaking out heavily reinforced concrete, were used to delicately remove tonnes of contaminated brick linings in a confined-space operation which demanded extreme safety precautions. “The bricks were coated with a 50mm thick layer of toxic chromium dust, and our range of versatile Brokk robots proved the most efficient and safest way to remove these linings”

explains Nick Turnbull, managing director of specialist demolition contractor Gnat UK.

At the heart of this process were six rotating cylindrical kilns, up to 100m long, used to heat and mix the various materials. Varying in diameters from 3m to 5m, these horizontal steel kilns had, over the years, built up a thick layer of fine chromic oxide powder known as ‘roast’. Its green pigment had fused onto and into the kilns internal lining which was formed of bricks laid end-on to create a 250mm thick protection

Confined Space Operations

The enclosed kilns were designated as confined spaces, so any proposed lining removal method necessitated a severe health and safety regime.

“Petrol or diesel driven plant would not have been allowed and operators have to wear fully sealed head gear with its own filtered air supply” says Elementis maintenance contracts engineer Bob Armstrong. “Gnat’s electrically powered robots, with operators able to stand some distance back from the working face, have offered an effective and very safe method.”

Methods and Means -

GNAT UK’s range of Demolition Robots offer varying sized arm reaches and hammer power ideal for tackling all kiln diameters. Access holes were cut in kiln sides and, for the narrowest 3m high vessel some 30m long, Gnat used one of their smaller robots the Brokk 90. Just 750mm wide, and with a 3.7m reach, the machine boasts an impressive 255 joules hammer power - equivalent to a standard robot three times its size

The slightly larger, 4.5m reach Brokk 180 tackles wider kilns, while two of the fleet’s heavyweight robots at that time, the 250 and 400, tackled the biggest 5m diameter vessels. As the removal of these sizeable kilns was critical to the plant’s entire £20 million decommissioning and demolition operation, two additional Brokk Robots were kept on permanent standby in case of mechanical issues. They weren’t needed! -

Further testament to the reliability of these robots!

A second opening, cut in the floor of each kiln, allowed bricks and roast powder coating to drop directly into a dump truck standing beneath. Here a simple, yet effective water spray funnelling arrangement surrounded the drop area with a fine mist ensuring minimal dust escape. “Without this dust suppressant we would have had to totally enclose the loading areas” points out Mr. Turnbull.

As the six month operation to remove some 200 tonnes of brick and chemical powder contaminant neared its successful end, Elementis’ Bob Armstrong shared his contractor’s satisfaction - “Gnat was not the lowest tenderer for this job, but the company has worked well in this plant several times already and both its performance and choice of robots are proving excellent” he says. “Obviously safety on this operation was paramount and the company has shown an exemplary standard.”

FAST FORWARDING towards 2023 - What’s NEW?

Whilst Kiln Stripping procedures may not have changed significantly since 2012, Gnat’s continued investment in State of the Art Robotic Technology enables us to confidently tackle the toughest, most demanding refractory wrecking work that the industry can throw at us - More Efficiently, More Safely - And Quicker!

Our latest Demolition Robots - BROKK 60's 70’s, 90's 200’s and 800’s, alongside HUSQVARNA DXR 140’s 250’s and 310’s deliver even more power, flexibility and manoeuvrability in the toughest of working environments

To view a selection the machines and attachments available for contract hire, with or without operator Please do get in touch!-

or contact us at:

or telephone 01748 826046

or complete our contact form!

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