The Armadillo in Action

The “Armadillo” is an Overhead Protection frame, a solution developed to complete the Tails Gas Stack clean out project during the 2022 IPL Mount Isa Turnaround.   

The project objective was to remove approximately 60 tonnes of acidic sulphate based material from a collection point on the stack, located 22 metres above ground. The sulphate levels were beginning to cause operational issues and posed environmental risks to surrounding areas due to material being ejected from the top of the stack. 

A number of complications have prevented this job from being completed in previous turnarounds since 2009. These included: 

• Acidic material destroying the vacuum truck 
• The vacuum truck not having adequate suction to remove dense material 
• Discovery that sections of steel flat bar are falling internally within stack from a height of 87 metres above the workspace.  
• Confined space is at 22 metres and has no simple access points. 

Together, Monadelphous Mechanical Engineer Daniel Gray and Site Manager Jason Merrin developed the concept then designed, procured and facilitated detail engineering, drafting and fabrication of the ‘Armadillo’ and a platform to allow for the manual excavation works.  

The Armadillo was created to provide overhead protection within the stack’s confined space, however Daniel said that it posed some unique engineering challenges.  

“One of the challenges was the steel that was observed falling internally in the stack – sections of 150x6mm flat bar estimated to weigh between six and ten kilograms,” Daniel said.  

“Over an 87 metre fall, these segments would develop the kinetic energy of a high calibre bullet.”  

To address this issue, impact perforation studies were performed and 16 millimetre quench tempered steel plate was selected as the ‘roof’ material. The significant mass of this roof also needed to be supported externally and be able to be rigged with counterweight for installation.  

A Bisaloy 80 roof plate was profile cut and rolled by the Monadelphous branch in Muswellbrook. Counterweight was then achieved with two three-tonne water load bags from Queensland Rigging Hire.   

“These were extremely effective in providing safe and highly accurate counterweight required to achieve balance and adjust centre of mass,” Daniel said.  

Minimising manual handling was also important for this job and was achieved with the inclusion of a conveyor and a demolition chute. Due to these assists, operators in the confined space were able to excavate the material at rates up to of five tonnes per hour. 

While this project is not yet complete, the Armadillo and platform have provided an innovative solution to a challenging job.

Pictured below: The Armadillo, an early design and the Armadillo in action.