The dirt is literally flying at the lignite mine presently operating in Choctaw County, MS, as a huge shovel removes layers of earth in order to reach the lignite (low-energy coal) buried hundreds of feet below. Following approximately three years of buying and/or leasing local area property, obtaining numerous permits and holding public hearings, actual digging at the mine began on Dec. 29, 1999.
The P&H 2800 electric-powered shovel’s bucket moves 40 cu. yds. (30.6 cu m) of dirt in one scoop. The 10,000-ft. (3,048 m) power cable attached to the giant piece of equipment receives 7,200 volts from its source and conducts 600 volts to the shovel. Horsepower output equals 3,500 (2,608 kW).
Purchased from Harnischfeger Corporation of Milwaukee, WI, the shovel was assembled on site. The order was placed in January 1999, and after six months of fabrication, pieces of the P&H 2800 began arriving at the mine.
Motors were pre-assembled. The shovel actually has seven different motors, each with a different function. For example, one hoists the bucket and another crowds the “machine” close to the bank.
A design and set-up crew from Harnischfeger arrived once the total order had been received. Assemblage went so smoothly in the following months that the shovel was work-ready in November, weeks ahead of schedule. Four County Electric, the local utility company, concluded its operations to provide power a short time later. The shovel was walked off the erection site fully operational on Dec. 19.
Total cost of the shovel was $7.5 million.
The shovel’s working weight — 1,189 tons (1,081.09 t) — posed the only real problem for the mining company. Mississippi’s soil has no rock base in its geologic strata, which is composed basically of clay.
In order to avoid the shovel’s possibly sinking from its own weight, larger-than-normal tracks measuring 108 in. (274 cm) across were attached. This particular undercarriage width generally is part of a 4100 shovel, the next largest machine above the 2800.
With its weight more evenly distributed, the shovel brings to bear 32 psi (2.2 bar).
Due to the time when actual operation began, full scale work did not start until mid January. Capable of digging a 40-ft. bench, the shovel will remove the overburden of earth at the mine site. The dirt will be loaded onto one of seven 150 tons (135.1 t) trucks and stored nearby for use in later reclamation of the land.
Three scoops of the P&H 2800’s capacious bucket can completely fill a truck. The speed at which the shovel digs can keep all seven trucks in various stages of operation at once. One truck can be loaded in 1.7 minutes.
Within one year, 11.5 million cu. yds. (8.8 million cu m) of earth can be moved. The truck shovel, as it is termed, will not be used for anything other than earthmoving, mine officials stated, and then only the higher levels of dirt will be involved. Remaining earth will be removed with large dozers and an 80 ft. (24.4 m) dragline to uncover six separate lignite seams.
To open the initial mine pit approximately 700 acres (28.3 ha) will be disturbed as mining progresses.
The size of the dug pits will measure approximately 1,600 cu. ft. (487.6 cu m) wide and the maximum depth will be 250 ft. (76.2 m).
Mississippi Lignite Mining company is a joint venture of Phillips Coal Company and North American Coal Corporation. Its sole purpose, said engineering manager Harry B. “Tres” Tipton III, is to provide lignite for use in the nearby Red Hills Power Plant. The predicted delivery date of the first load of ore is October 2000.
Some initial dirtwork and construction was done via subcontracting with Yates Construction of Philadelphia, MS. Mining facilities were built by Sam Oswalt & Sons, located in the nearby town of Mathiston.
The mining project has a 30-year contract.
Today's top stories
