Features, Innovation, Repair and maintenance, Work health and safety

Game-changer in mill relining safety

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Bradken’s MillSafe Solutions are keeping personnel safer during mill relining. 

A grinding mill is a critical asset to a mining operation. Capable of breaking down ore, these incredibly powerful machines are built from equally robust materials. 

It’s precisely this combination that makes them hazardous for workers during maintenance. 

One of the most hazardous aspects of mill maintenance is the relining process, as it involves workers accessing the interior of the grinding mill, which is classified as a confined space. 

The grinding mill needs to be isolated and safe for people to enter the confined space. The worn liners are removed and the mill shell is manually cleaned in preparation for new liner installation. New steel liners are then installed, and these can weigh up to five tonnes each. 

Traditionally, steel liners are bolted in manually from inside the mill, a process that involves workers operating near heavy machinery and suspended loads for hours at a time. 

Relining a mill chamber usually can take up to 100 hours to complete.

“During a reline the mill requires good lighting and ventilation to create a safe working environment. Furthermore, the use of heavy equipment during the relining process contributes to a highly hazardous area of work for the reline crew,” Bradken principal product manager Craig Faulkner told Safe to Work.

Bradken’s values focus on protecting personnel. The company’s ‘Arrive safe, Leave safe’ philosophy helped to fuel the development of the MillSafe solution. 

According to Bradken, “the end-to-end mill lining system aims to deliver state-of-the art, cutting-edge technology that seamlessly integrates while providing uncompromising safety measures during the relining process”.

Bradken’s suite of MillSafe solutions has been designed to reduce risk and remove workers from the inside of grinding mills during relining, making it a safer process.

The suite is comprised of the following products: MillSafe Bolting system, MillSafe Backing, MillSafe Liner Location Stripes, and MillSafe Combined Corner Liners. These are all compatible with autogenous (AG), semi-autogenous (SAG) and ball mills.

Mill liners are traditionally held in place by a reline machine while personnel bolt them onto the shell wall from inside the mill. With the MillSafe Bolting system, liners can now be bolted on from outside of the mill.

“By installing the bolts from outside, there is no need for maintenance personnel to be in the vicinity of the reline machine during liner placement and positioning of the bolt holes, making it a much safer practice,” Faulkner said.

bradken, mill relining
The MillSafe bolting system minimises worker exposure to hazardous environments. Image: Bradken

The internal mill shell is typically lined with a 6mm rubber sheet to protect the mill shell and create a consistent seating area for the steel liners. Personnel normally need to manually clean the mill shell and repair damaged rubber sections, which can require spending hours scraping off the worn-down rubber and replacing it, but with Bradken’s MillSafe Backing that’s no longer the case.

“MillSafe Backing is an integral coating on the fit face of our liners, reducing the need for personnel to access the mill to repair the rubber sheeting” Faulkner said. “In addition, MillSafe Backing wraps around the side of the liners to eliminate the need for rubber filler strips, removing another process where personnel have to enter the mill.”

Bradken’s MillSafe Combined Corner Liners are cast as part of the liner, eliminating loose corner liners and the risk posed by traditional products. This also has the benefit of reducing overall liner mass. 

Safety incidents have been recorded during relining where the unsecured loose corner liners have fallen in close proximity to the reline crew and, in some cases, resulting in injury. 

Bradken analysed the benefit of the MillSafe Combined Corner Liners on a 40-foot SAG mill. 

This resulted in the reduction of 60 liners required, saving an estimated 12 hours in relining time. It also supported an increase in mill availability, which improved the operation’s profitability.

Finally, Bradken’s MillSafe Liner Location Stripes provide visual guidance to position the liners and deliver a safer and more efficient liner install.

Faulkner noted that the MillSafe suite really came into its own two years ago, when one of Bradken’s customers was looking to fully automate the relining process for a grinding mill. 

“This aligned with our vision and the opportunity to improve mine site safety standards and reline efficiency across the global mining industry,” Faulkner said. 

“Miners are always looking for opportunities to reduce risk to their personnel, and the MillSafe suite of products presents that opportunity.

“Bradken continues to look for opportunities to partner with our customers to deliver sustainable solutions that optimise safety and performance.” 

This feature also appears in the March-April issue of Safe to Work.

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