1916: Mechanical Equipment for Mining Coal:
The Thew Loading Shovels and Joy Loading Machines
Images and notes by Bob Leathers
The Thew was first used in 1916 in the Union Pacific Coal Company's No. 4 mine in Hanna..
It was in this mine [Hanna No. 4] that the first mechanical equipment for loading coal was installed in a mine of The Union Pacific Coal Company, and this was likewise in the first installation west of the Mississippi River. Small Thew dirt-handling shovels were installed in 1916, as no mechanical coal-loading equipment had been perfected and placed on the market at that time. These shovels required a minimum height of 16 feet in which to operate, and this did not constitute much of a problem in a seam of coal 20 or more feet in height.
The next development was the installation of 4-BU Joy loading machines to speed up pioneer development work, which was driven from 8 to 10 feet high, to be followed later with the Thew machines, which loaded out the remaining 10 to 15 feet of top coal.
The Thew machines are now obsolete , and all coal is now being loaded out in two benches by the use of modern Joy coal-loading machines. This mine [Hanna No. 4] is now 100 per cent mechanized. The mine is gaseous, but is well ventilated, and rock dusted throughout. The general Safety standards of The Union Pacific Coal Company are being maintained at this mine, adding greatly to the safety of operation. (UPCCEM, November 1940)
The Hanna Coal Basin
by C. E. Swan
An article on the Geology of Hanna Coal Basin, written by Mr. O.G. Sharrer, appeared in the April 1926 issue of the Employes’ Magazine and the present article deals with a general description of the workable part of the field and with mining conditions encountered by the Hanna Mines.
The known workable coal seams in the Hanna District occur in the Tertiary Geological Age; the portion in the vicinity of Hanna being termed the Hanna Formation by the U.S. Geological Survey. There are four workable seams at Hanna known as No. 1 Seam, Peacock Seam, No. 2 Seam and No. 5 Seam. While the Peacock is a good quality coal seam 6 to 8 feet thick, it has not been worked on account of the soft rock just over the coal and the fact that the thicker seams are easier mining propositions in this district.
The Geological section of the Hanna Coal Measures (see cut) shows a typical cross section across the center of the field of coal which has been extensively worked near the town of Hanna, Wyoming. This cross section shows these seams as continuous across the basin from West to East but according to our present knowledge the No. 1 Seam is the only one containing workable coal all the way across.
A series of seams on the east flank may represent the No. 2 Seam east outcrop and a black shale ledge may be the east outcrop of No. 5 Seam, but considerably more research work will have to be done before the east outcrop of these coal seams can be positively identified.
The field is cut by a series of west to east faults of various throws and the block of coal mined out by No. 3 1/2 Mine lies between two such faults. The block was dropped down approximately 100 feet below the general level of the floor of the basin.
The southern tip of another basin which contains these same seams outcrops about two and one-half miles northeast of Hanna No. 3 Mine workings. This basis appears to extend in a general northeasterly direction and to be an extension of the same geological folding which formed the area that has been mined at Hanna.
The No. 2 Seam lies geologically 1,350 feet below the No. 1 Seam while the Peacock Seam is located between the No. 1 and No. 2 Seams. The No. 5 Seam is geologically 1,450 feet below the No. 2 Seam. Known workable coal on No. 2 Seam extends from the west outcrop down the pitch at No. 2 Mine for a distance of 5,000 feet. No. 4 Mine on No. 2 Seam reached a depth of over 1,000 feet of overburden and the coal still retains its height.
The No. 5 Seam has only been proven workable on the west side by surface prospects and diamond drill holes for a distance down the pitch of 4,000 feet, but future drilling may prove it extends much further.
The No. 1 Seam of coal has practically been exhausted from the north three quarters are of the basin by Mines Nos. 1, 3 1/2, and 3 and the remaining one-quarter south of the big upthrow fault is of more or less uncertain cleanness but may be worked in the future.
The basin of coal as developed in the No. 1 Seam shows same to have an oblong bowl shape the long central axis of which extends in a northeasterly direction. The basin in the No. 1 Seam is 1 1/2 miles wide at the Hanna No. 1 Mine and the northeast or long axis is approximately 3 1/2 miles in extent.
The coal in the workable seams is a good grade of lignite which makes a fair locomotive fuel and a good grade of coal for domestic use. The No. 1 Seam of coal averages 18 to 25 feet in thickness with a small area of coal only 6 to 8 feet high. No. 2 Seam averaged 18 to 35 feet in thickness from the west outcrop down 3,800 feet but has pinched down to 7 feet at the face of No. 2 Mine slope. No. 5 Seam in surface prospects and diamond drill holes show a split seam with the following section from floor to roof:
2’ to 12’ coal,
2’ to 3’1/2 shale parting,
6’ to 12’ coal.
The overburden over the coal in the Hanna District is composed of soft shales and sandrocks with a soft shale predominating next to the coal seams which necessitates leaving part of the seams to form a roof. In the No. 2 Seam, upper working, the top 5 to 8 feet of seam is composed of dirty coal and this is left up to support the roof.
On account of the great height of coal in these seams it is possible to mine strike rooms (rooms driven at right angles to the dip of seam) with a level floor by leaving bottom coal on the low side of the rooms. By reason of the facts stated, The Hanna mines lend themselves readily to mechanical methods of mining and it was in these mines The Union Pacific Coal Company first attempted to load coal mechanically by the installation of Thew dirt loading shovels. (UPCCEM, September 1927)
For additional detailed information on the mechanical mining efforts in the Hanna mines: The Union Pacific Coal Company from the Mining Congress Journal