Published in the August 2005 American Longwall Magazine
In May 2005, Tampa, Florida-based Walter Industries announced a long-term plan for mine production increases at it subsidiary, Jim Walter Resources (JWR). The announcement resulted from a decision to invest approximately $135 million to expand JWR’s Mine No. 7 in Brookwood, Alabama.
Because of this expansion and subsequent increase in production, JWR will have an additional 4.4 million tons of low-vol metallurgical coal available for sale, predominantly between 2006-09.
No. 7 mine is a single longwall mine with three continuous miner sections. The project is to drive three access roadways through several faults into a new area and then duplicate the existing mine. “A mirror image mine,” said JWR president George Richmond.
With the planned expansion, the site will also see significant changes in order to keep the operation running at prime production levels for years to come. The mine is expected to be operating for at least another two decades. Richmond estimates approximately 20,000 clean tons per day production once the No. 7 mine’s extension is running at full speed.
Richmond added that while the current mine advances north, the expansion will move east. In the east extension side of the mine, ventilation shafts and a new portal, complete with its own bathhouse, will be constructed.
Under the new plan, coal will emerge from each side of the mine and travel an existing main north beltline. To maximize output, the company plans to add a 4000t bunker where both conveyor systems will meet. The existing belts will not be upgraded.
Enhancements will be made to increase hoist capacity, Richmond said, so the company had planned a parallel hoisting system. “The existing production shaft is not capable of hoisting coal from two longwalls and six continuous miner sections. The present production shaft has a 28,000t/d capacity.
“We will be converting an obsolete fan shaft into a second production hoist, which will then increase the hoisting capacity of the mine to 56,000t/d.”
The existing preparation plant will also be cleaning twice as much product, so a “significant expansion” will be done to that facility. The current throughput is 1200t per hour, and will more than double to 2600t/h when running at full production after the expansion.
Face widths will remain much the same as now. Current longwalls are 13,000ft long and 850ft wide. Depending primarily on faulting that may be encountered along the way, Richmond estimates some of the new longwalls could extend up to 18,000ft.
While plans are well under way for the expansion, Richmond notes, not all decisions have been made. “Right now, we haven’t made a final decision on the roof supports and the equipment for the second longwall.”
JWR’s expansion plan includes increasing productivity of the existing longwall. The current supports will not allow mining below 75in because of support density. In the short-term, JWR has renovated some older roof supports to increase their efficiency.
However, Richmond noted, for long-term success new roof supports needed to be purchased. Scheduled for delivery and installation by year’s end, the new DBT supports will have significantly higher densities to operate at a lower range.
Prior to the completion of the east side expansion, JWR intends installing a second longwall operation, mining a single panel in the south-west section. “Currently, we’re in the process of rehabilitating old entries to get to that panel,” Richmond said.
“Section development rates in the No. 7 mine have been increasing for quite a while.”
As they study miner bolter performance at No. 4 mine, they are considering the same for No. 7.
More powerful continuous miners are also on the agenda, Richmond added. “We have three sets of continuous miner equipment on order, which include 12CM-27 miners, Joy 10SC shuttlecars, ARO platform bolters, and McClanahan feeder breakers.”
With JWR’s capacity scheduled to jump from 6.9Mt in 2006 to 8.8Mt by 2009, Richmond identified all of the components of the expansion as equal vital factors to the critical path of the project, but did not foresee any issues. “Fault crossing, the shaft developments, design and construction of a new bunker, completing prep plant expansion, and installing a second production hoist – that’s really the critical path.”
With the No. 7 project under way, JWR is already in the process of improving production at its No. 4 mine. Production levels are limited due to the existing hoist capacity. “We have a project ongoing this year, including modifications to the production hoist, giving us approximately 10% increase in hoisting capacity,” said Richmond.
