The benchmarking surveys are part of the overall roadway development improvement project.

 

In the first study looking at the June 2006 quarter, only 15 out of 26 mines responded (only 24 of the 36 continuous miners provided production data), and some of those responses were incomplete.

 

While the June 2006 benchmarking results showed “considerable promise”, project leader Gary Gibson said more data was needed to provide definitive results that could be acted on by industry.

 

A statistical analysis carried out by Colin Bertram from the University of Wollongong on the first set of data showed:

• Continuous miner units that achieved more than 1750m over three months were units mining two-heading development.
• Having six bolting rigs (four roof and two rib bolting rigs) improves the probability of higher development metres, while having fewer than six heavily limits performance capability.
• Installing 1500mm rib bolts appears to limit development rates, as continuous miners achieving higher production levels all install 1200mm rib bolts.
• Continuous miner units achieving more than 1750m were loading coal out through floor mounted conveyor systems, although further analysis of the data identified that mines with roof mounted conveyors also had continuous miners fitted with only two bolting rigs per machine. Therefore, additional data sets would be required to confirm whether a direct or symptomatic relationship existed between roof and floor mounted conveyors, bolting rigs, and continuous miner performance.
• The majority of the continuous miner units that achieved less than 1000m had weekday shift lengths of eight-hour duration.
• Mains development units driving five-heading mains achieved fewer metres overall during the three-month period than those units that drove four-heading mains.
• Longer pillars may also contribute to improved development rates, a factor which is at odds with current beliefs and perceptions.
• Higher roof bolting densities didn’t necessarily slow development rates, whereas rib bolting density does appear to. This may suggest a strong relationship between bolting density and the number of bolting rigs actually fitted.

 

A December half-year benchmarking study has now been issued to the industry. Gibson encouraged mine managers and development coordinators to complete the study so that factors affecting development performance may be better quantified, “thus enabling them to make decisions regarding improved development performance with improved certainty”