New infrastructure, including more than 64,000 feet of underground and overland conveyor – the latter accounts for 14,000 of that total – rolls through the Appalachian foothills like a rollercoaster to the mine’s Shoemaker preparation facility along the Ohio River at Shoemaker Harbor.
Until January 2010, the large Marshall County mine had held the distinction of being the last remaining underground mine to use rail car haulage.
Shoemaker is of typical depth for the region, having 600-700ft of overburden. With one longwall panel and three continuous miner sections at press time (this will grow to four later this year), the three shifts of about 206 workers each are kept busy.
Currently, the operation is completing its last three panels in the 8 North Mains before moving personnel and equipment to a new area at 8 South adjacent to its main Golden Ridge portal.
Development is occurring in that area now via two CMs.
Until the longwall joins the 8 South CMs in 2012, workers continue the trek to the mine’s active 8 North sections, a 15,000ft trip which takes about 30 minutes aboard one of the mine’s Goodman and Eimco DC-powered rail mantrips. Once in the new area, the DC haulage will continue to be used but at some point will be transitioned to diesel units.
Shoemaker extracts from the prolific Pittsburgh 8 seam, where a longwall shearer has been rapidly cutting away since first installed in April 1975.
Current longwall panels are on average 1000ft wide and a healthy length of about 10,800ft.
Cutting height is 65-72in, while seam heights typically will match.
Longwall production was temporarily suspended at the northern Appalachian complex as the meat of the mine’s major belt overhaul was completed, but resumed January 15 with as much vim and vigor as ever.
In fact, superintendent Bob Wise noted, the panel and its crew were patiently awaiting its return to prime advancement levels this summer when a collection of planned upgrades are wrapped.
A Joy 7LS-1A shearer with 62in headgate and tailgate drum diameters powered by 710hp per arm glides along the Pittsburgh 8, passing 174 Bucyrus PM4 800-ton shields on passes that take about 45 minutes per cycle. Coal falls to the Bucyrus 1m face conveyor with Fenner Dunlop belt and 42mm Thiele chain moving at approximately 250ft/min. The headgate 1 and 2 are running at 750hp and the tailgate is powered at 800hp.
The BSL and crusher are both MTA/Bucyrus, with a 10-12in clearance range on the latter.
Overall, the longwall produces about 20,000t daily averaging approximately 75ft/day of retreat at 2500tph capacity. Equipment availability typically remains in the range of 85-95%, depending on mining equipment and belt conveyor availability.
When Shoemaker readies for a longwall move, management creates a detailed plan for longwall recovery execution as well as safety of the workers involved.
The move takes an average of six days, and includes the company’s standard process of recovery screens with resin bolts and straps ahead of the shield tips.
Shoemaker continues to cut out its future minewide: development headings total five entries in the 8 North Mains, eight entries in the 8 South mains, and three entry gate sections – all being driven by Joy or VA continuous miners. Typical roadway pillars are 60ft by 130ft.
Six, eight, 12 and 16ft Jennmar tension-grouted bolts are all used at various areas, with 6ft standard and the longer lengths being used in the centers as center bolts as well as intersections.
All are on 4ft spacing with straps, and crews secure all belt and track entries with rib bolts.
While the mine takes extra steps to ensure good ground control, management noted that geology is already stable overall. Above the rich Pittsburgh 8 is about 4-6ft of laminated shale with a firm limestone formation above that.
The biggest ground control issue, Wise said, is control of the immediate roof, and for that reason the company has gone the extra mile with its ground control techniques.
Gas at the operation is always maintained at safe levels and there is a great deal of effort to ensure it remains that way. The mine does not conduct pre-drainage but prides itself on a robust ventilation design.
The circuit includes line curtain and100hp auxiliary face fans, as well as oneblowing and six exhausting dual compartment fans, six single compartment shafts (two bleeder), as well as one single intake and one single return.
Once coal is pulled from the active faces of the mine, a series of 15 belt flights move the output from Shoemaker’s sizeable underground design. All utilize 480-volt variable frequency drives; 54in maingate belts run at 3000tph and 60in trunk belts roll at 4000tph.
Shoemaker works with two original equipment manufacturers on the infrastructure, which is still ramping up since wrapping the significant upgrade project. Belts 1 through 11 are Allison Custom Fabricating, and 12 through 15 are Harrison Conveyor.
Regarding the latter group of 60in belts, Wise pointed out that the lower speed and horsepower will eventually match and be compatible with the first 11 belt flights, as the scheduled upgrades will be completed later this year.
Much like its sister mines across Consol’s portfolio, Shoemaker’s underground environment is quite clean, evidence of its comprehensive focus on worker safety and maintenance.
That attention extends to its equipment, which is part of the operator’s preventative maintenance program staffed by 7-9 experts per shift who devote more than 140 hours weekly to the smooth operation of the mine.
Complete status reports are also provided daily to the mine’s master mechanic. This practice, according to management, ensures equipment standards are kept at or above Consol’s corporate safety specs.
Despite its age, Shoemaker still sets a positive, safe and productive example for other mines large and small, particularly for its northern Appalachian neighbors.
It has budgeted 4.6Mt for 2010, and at press time was well on its way to meeting that goal with over 1Mt already mined.
With more than 90Mt remaining in the ample, rich Pittsburgh 8, the multi-million renovations to the belt infrastructure have revitalized the mine and its people for a strong second wind.
As the pace picks up once again to prime production levels, Shoemaker’s hundreds-strong team is ready for the upswing while remaining committed to Consol’s Absolute Zero miner safety philosophy.
- Owner: Consol Energy
- Location: Dallas, WV
- Mining started: 1966
- Longwall started: April 1975
- Seam/cutting height: 64-72in
- Remaining reserves: 90Mt; Approx. 20 years
- Employees: 618 across three shifts
- 2010 budget: 4.6Mt