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This is one of the key findings from recent Australian research into improving roadway development rates. The research was funded by the Australian Coal Association Research Program (ACARP) to identify what was needed to improve roadway development rates to support a new generation of longwall mines.

The failure of roadway development rates to keep up with advances in longwall production was identified in 1994 by ACARP’s Underground Technical Committee. Even then, with longwall mines projected to be producing at rates of 5Mtpa to 8Mtpa by 2004, it was clear development rates would not be able to keep up with longwall production rates.

The industry tried to adopt a systems approach with a focus on panel, pillar and cutting cycles, as opposed to equipment and technology, but only a small number of mines successfully applied the approach.

Now with mines of the future being planned at almost double those outputs, improving development rates is again a top agenda item. However, now the focus has shifted to how equipment and technology can forge the way forward.

The technical committee commissioned industry consultant Gary Gibson to collect benchmark data on performance in the industry. Some 160 mine operators, contractors, researchers, OEMs, and other industry stakeholders provided feedback during the research.

The good news is technology now being developed is expected to address a number of key process constraints and should improve system capability across all mines. International Longwall News will examine what’s on the horizon in coming weeks.

Participants said carrying out roof and particularly rib support was the most significant constraint to development rates, as well as the stop-start nature of coal haulers. Installing ventilation duct and advancing conveyor and panel services were other identified constraints, as well as the handling logistics around support consumables.

Furthermore, the sheer physical demands of the job coupled with an ageing workforce made it hard to improve development rates.

The industry outlined a shopping list of requirements of a new roadway development system that will be able to achieve improved development rates. This included self drilling bolts, automated bolting, continuous haulage, self advancing extensible panel conveyor, and a monorail mounted services management system.

Researchers said work on most, if not all, these areas was underway. For example, there are five self drilling bolting systems currently in various stages of development for application in the coal industry. (See related article, to be published DATE)

Several constraints face the successful development of new development technology. Sustaining long-term research for a small market is always difficult, as is finding a way to test and demonstrate new equipment in operating mines.

Researchers also pointed to the limitations posed by overly restrictive legislation “coupled with the over-zealous pursuit of absolute safety first”

Nevertheless, there are many things mine operators can do. One of which is for mines to commit to a routine roadway development benchmarking process with published results. A shift in focus was also suggested so that development sections were adequately resourced with both expertise and equipment.

For its part ACARP is putting together a roadmap that aims to demonstrate by the end of 2006, a high capacity, integrated mining system that incorporates the technology identified by the industry.

So, what are the best mines doing right?

Later generation best practice mines with good conditions are typically achieving 300m per week per development unit, or in the case of super unit mines 400m per week per super unit, when mining at heights of 3m to 4m.

A 300m wide, 4km long panel typically requires 682m per week of development to sustain a 15Mtpa longwall in a 3m thick seam. This reduces to 585m per week in a 3.5m mining section and 512m per week in a 4m mining section.

Wider faces and longer blocks reduce the development burden, as does the use of punch longwalls that do no mains development.

“Average performing” later generation mines achieving around 200m per week (continuous miner), or 265m per week (super unit), could sustain 15Mtpa longwall mines with mining at heights of 3m to 4m.

But it is unlikely worst later generation mines at the less than 100m per week or less than 130m per week mark could reasonably sustain 15Mtpa longwall mines.