An experienced eye on site can pick up minute changes and this can make all the difference.
From a potential wall failure to a roof collapse, having the right people watching is key.
However, monitoring of your equipment is not just something that occurs at the mine itself, with proper monitoring crucial from OEMs onwards.
Training aids in creating this maintenance and monitoring experience, with roof bolt manufacturer Dywidag Systems International (DSI) saying experience and diligence recently averted a potential disaster at an underground coal mine.
In early December last year, during a scheduled 2.1 metre roof bolt production run, one of the operators working the shear noticed that some of the steel bars being prepared for roof bolt manufacturer would cut much more easily than others in the same batch.
After carrying out an inspection, the operator found that all bars were labelled correctly – AX Grade steel as ordered – but following further testing they found that a few of the bars in the bundle being worked were actually 300Plus Grade.
The difference between AX Grade and 300Plus Grade is high.
While both exhibit the same physical characteristics, the 300Plus only has a nominal load bearing capacity of 19 tonnes compared to the tougher AX Grade at 34 tonnes.
DSI explained that to achieve the improved load bearing capacity, the AX Grade contains about one per cent manganese – which the company would use as a reference point as part of its inspection programs.
As soon as the cross contamination of the steel batches became apparent, the company said that it carried out a massive 'Quality Assurance and Quality Control' program to track and quarantine any and all mislabelled roof bolts that had been manufactured and sent to customers.
"As a roof bolt manufacturer, this was not the type of scenario we wanted to be confronted with," DSI chief executive Derek Hird explained.
Luckily "we knew we had the QA and QC system in place to track down any bolts that had been dispatched".
According to the company, following the program it quickly received 'some early good news' from a steel supplier who was able to confirm that the 'contaminated' AX Grade steel was confined to a very small group of products supplied to DSI.
"Apart from reassuring the broader coal mining market that bolts from other manufacturers were safe ¬such knowledge also helped DSI track any delivered bolts more quickly," Hird said.
More than 2500 bolts were tested.
DSI said that in all, four underground mines were identified as the potential recipients of the bolts manufactured from the lower grade steel.
Hird stated that each customer was contacted and given a full run down of the situation, as well as advised of a site inspection.
"We decided that our staff would go to sites where products had been received and, in conjunction with the site authorities – typically the technical services manager – physically test all their bolts, both those installed and in storage," he said.
Each inspection team had an XRF Alloy Analyser to detect the bolts' manganese levels.
With the manganese levels in the 300Plus Grade typically only in the .65 to .85 per cent, the teams were quickly able to separate these from AX Grade bolts with levels of 1 per cent and over.
The testing teams made sure to brush all bolt surfaces to obtain better readings.
Hird said that on 12 December, within four days of the first discovery, these inspection teams hit mine sites.
"The inspection program continued over the Christmas holidays and was completed by 21 February."
He said that despite the initial problem, the overall outcome was positive as it has given the company a real life test of its monitoring and response procedures.
"As a company we put policies in place as a step by step guide to resolving issues around scenarios such as supplying product contrary to what was ordered.
"This incident involving the incorrect feed steel supply took us one step before quality production policy was active but we could still resolve the situation quickly, efficiently, and maintain product quality," Hird added.