Published in American Longwall Magazine

Located near Paonia, Colorado, the Bowie Resources owned mine has been producing steam coal from Bowie 2 mine since January 1997. Bowie Resources acquired the mine a year ago after previous owner Horizon Natural Energy declared bankruptcy. Longwall mining began in 2000 with the commissioning of a five million ton per year capacity system.

Bowie produces a high Btu, low sulfur run-of-mine steam coal which is supplied to local power utilities by train. A train loader is fed by a high speed belt reclaiming from a 350,000-ton live stockpile. The mine is blessed with large recoverable reserves in excess of 100 million tons.

Last December Bowie received state permits to build a washplant with the capacity of up to two million tons per year. The washplant will be fed coal from the new B seam.

Underground mining is currently taking place in the thick Paonia Somerset D seam at a depth ranging from 500-1500ft. Mining will be completed in the current panel, and one more in the west of the reserve, before the longwall is relocated to the lower B seam, some 300ft deeper.

No new equipment is required in the B seam but according to maintenance manager Dewey Tanner Bowie is considering buying new shields to improve recovery. Should the mine decide to take this path an order would be placed in mid-2005.

The state mining agency approved Bowie's B-seam plan in November 2003. Mains leading into the B seam are currently being driven off a bench in the canyon wall with continuous miners.

While geological conditions in the lower seam are expected to be much the same, increased pressure from the upper workings is anticipated.

Bowie is the only US mine using DBT's newly released EL2000 shearer, commissioned in July this year. The shearer incorporates ranging arms from the earlier EL1000 shearer but the mine is in the process of upgrading to new more powerful ranging arms.

Other than Xstrata Coal's Beltana mine in Australia, Bowie is the only mine to use DBT's newly released Saminco variable frequency drive on the shearer.

Designed specifically for mid seam applications, the EL2000 shearer incorporates many of the developments in the latest generation of EL3000 shearers. Despite being a physically smaller machine, the new EL2000 shearer has the same level of installed power as the first generation of EL3000 shearer.

By all accounts the mine is pleased with the shearer's performance to date. During September 13,128t were produced per 10-hour unit shift on the longwall.

According to longwall coordinator Rodney Pretti the impetus behind the purchase of the new shearer was to improve the ability to mine between the visible top and bottom parting in the seam - not possible with a larger profile shearer.

Pretti added the new machine was user-friendly and easier to maintain than the previous DC haulage shearer.

"With those old vintage machines we were talking super high maintenance. We have in the past changed up to 12 DC motors over one panel."

Bowie uses a half-web cutting system to cut 70% of the face headgate to tailgate at about 135ft per minute and the remaining 30% at about 80ft per minute on the return.

While the shearer operators do not use the automation features in the machine, this is compensated for by their efficiency and skill. Limiting factors on shearer performance are the mine's one mile long conveyor and 54in panel belts.

Panels are typically 825ft wide and about 7000ft long, although this year's panel length was short, constrained by geological features, with the shortest panel only 2400ft long. Due to this the mine will have completed three longwall moves this year.

There are four vintages of roof supports on the longwall face with 40 new DBT supports bought in 2002.

Gateroad development is currently focused on establishing the first panel in the B seam.

Two Joy 12CM12s and one 12CM27 are developing three sections, supported by Joy 10SC32 shuttle cars. A Stamler feeder breaker dumps on to a 54in belt.

Development crews average 220ft per ten-hour shift. The roof is supported by 18ft wide mesh, with four 6ft bolts installed every 4-5ft.

Tailgate support is achieved with a cable truss installed every 5ft, supplemented by a 12ft bolt with a 'baseball' stitch arrangement staggered every 5ft. CAN supports at 12ft centers provide a centerline of support.

When Bowie introduced the longwall, two downhill regenerative conveyors were installed to transfer coal from the upper bench to a 350,000t pushed stockpile at the foot of the mountain. The conveyor system was designed by engineering company Roberts and Schaefer.

These conveyors are 48in wide, rated at 1500t per hour capacity with a belt speed of 550ft per minute. The transfer conveyor is 950ft long with 140ft elevation drop, powered by a 200hp motor with variable frequency drive. The conveyor transfers coal from the upper bench to a downhill conveyor 2750ft long with 1620ft elevation drop, powered by two 400hp motors.

The stockpile at the foot of the mountain comprises two stacking tubes and a 16ft diameter multi-plate reclaim tunnel with four hopper openings. A 6000tph reclaim conveyor transfers coal directly to a new rail loadout facility eliminating truck haulage on public roads.

Both conveyors are automatically controlled by a PLC with the main processor at the loadout area and remote racks at other key locations, all connected by a fiber optic highway. The conveyors are regenerative, creating electrical power from the gravitational energy of the conveyors and placing the power back on the grid.

Safety statistics at Bowie are impressive with the mine running at roughly a third of the national average in terms of incidents and injuries.

"Until very recently we went 424 days without a lost time injury. Our citation rate and incident rate is really good," Tanner said.

A high percentage of the mine workforce hold mine foreman papers, making them one of the most skilled workforces in the industry. There is no union presence at the operation and employees participate in production and safety incentive programs.

The mine received industry recognition in 2002 from the Colorado Mining Association for a significant reduction in incident rates. Since then the company has continued its focus on safety with a program which includes regular meetings, extensive safety training and incentive programs to increase employee awareness and foster a positive safety attitude.