The introduction of a comprehensive strata management plan is producing impressive results at Crinum mine in the Bowen Basin. The longwall set a record 1.55 million tonnes for the third quarter of the fiscal year – averaging 9,900 tonnes per shift – and a monthly record of 670,000t in April. This strong performance has resulted in mine production of around 5 Mt in just over 11 months.

Difficult geological conditions, particularly a soft roof, have hampered production since Crinum began longwall operations in 1997. A comprehensive strata management plan, geotechnical expertise and a move from five to seven day rosters have helped turn that around.

Registered mine manager Gavin Taylor said Crinum introduced seven by 2 x 12-hour shifts for the longwall in May last year.

“We’ve usually had good production rates at Crinum, but they’ve been interspersed at various times with roof control problems,” he said.

“We recognised some time ago that our coal is extremely soft and it allows the roof to subside in front of the face. If we stop for extended periods, we tend to smash the roof up in front of us.

“Since we’ve been on seven day production, we’ve had excellent production from the longwall, because we’ve minimised down-time through broken roof. We were also able to utilise the same numbers of people more effectively going to 12 hour rosters.”

Taylor said he was impressed with the performance of the longwall team.

“They are a very well motivated group of people, focused on safety and productivity. They are continuing to achieve exceptional tonnages in very trying and difficult geological conditions,” he said. “We’re maintaining very high operational standards on the face and those operational standards are paying dividends for us.”

Taylor said the mine “strictly adhered to” a detailed strata management plan that incorporated step-by-step processes for every eventuality, including what corrective actions needed to be taken and who needed to be notified. The addition of a geotechnical engineer and a new longwall coordinator has strengthened the mine’s technical skill base.

Taylor said the mine was in the midst of a longwall take off. Longwall 5 started production in November 1999 and produced 2.6 million tonnes of coal from a 2km panel. Longwall 6 is expected to be in production just before the start of the new fiscal year.

On the development front, performance is starting to improve. The crews have had to install megabolts to deal with extremely soft roof conditions, which has slowed down development rates.

“We’re out of the worst of the ground conditions and we’re actually seeing some better development rates at the present stage,” Taylor said. “For the density of support that we put in, we are travelling very well, we are up there with the best of them.”

Taylor said Crinum was focusing on getting back to basics: “We’re trying to make sure we’re doing the basics right, then safety, costs and operations will flow from the end of that.”