1923 mining review article

The following article is from an issue of Chemical Engineering and Mining Review of 5 February 1923.

Coal Mining in New South Wales - XXI

The Western District
by William Humble, late Chief Inspector of Coal Mines

State Coal Mine, Lithgow

Morts Gully

It is situated in Mort's Gully, about 11 miles north of the main western railway at Eskbank. Its area of holding is about 10,000 acres of crown lands most all of which has the main Lithgow coal seam of workable section. The site of the shafts having been decided on in 1916, a start was made to sink the upcast shaft through the alluvium covering the bed of Mort's Gully, boilers and sufficient machinery having been carried to the site by drays and motor transport. After a deal of difficult work had been done on the shaft, the New South Wales cabinet decided to suspend all operations, and this was done on July 10, 1917. In 1920 parliament passed a short act vesting the control and working of the mine in the chief commissioner of railways for the purpose of supplying coal for the use of the railways.

Early Stages

The work done while the control of the mine was in the hands of the mines department consisted chiefly of clearing the site, erection of sinking headgear, winches, etc., and the sinking of the up-cast shaft through the alluvial deposits and into solid strata, a depth of some 80 ft, the shaft sides being secured through the alluvium by sheet piling, the ordinary ring curbs and timber being used on the underlying strata. Operations were suspended in 1917, the reason given for so doing being that war conditions affecting the financial side of the matter made it inadvisable, to carry on at that stage. The place remained shut down till April 1921, when operations were resumed by the railway commissioners. After unwatering the shaft, the depth already sunk through was secured by bricking, when sinking recommenced, operations being concentrated on the getting down of one shaft first. Water gave considerable trouble in the initial stages of the sinking.

This, however, was largely minimised later by the putting in of a water ring and the driving of an "inset" into which the water was collected and pumped to the surface. The strata passed through consisted chiefly of drift sand and shingle, shales, and sandstone, the total depth to the floor of the seam being 263 ft. This shaft was bottomed in November, 1921, when headings north and south were turned away.

A commencement was then made with the sinking of No. 2 or downcast shaft. This shaft was carried down in much the same way as the previous one, when the permanent walling was put in for this depth, concrete 18 in. thick being used. This effectually sealed back the flow of water from the alluviums. Sinking then continued and operations were later expedited by rising for a short distance from a heading in the coal seam. In the sinkings, jackhammers (air driven) were used and gave very good results in the shale strata.

For keeping the shaft dry the ordinary “duplex” type of pump was used. This was seated on the sinking cradle and driven by compressed air. All sinking shots were electrically fired.

Owing to the restricted area available for mining in the vicinity of the shafts (the main area lying practically due north about 1 1/4 miles away), a large output was not looked for, at least for some considerable time ahead. To reach the main area two pairs of headings and a separate travelling way (five places) were set away, and these, with their necessary cut-throughs, together with a limited amount of the bord area south and west, have afforded an 'increasing output which at present is 750 tons per day of two shifts.

The probable output for 1922 is 65,000 to 70,000 tons and about 290 persons are employed - 130 underground, and 160 on the surface. The estimated output for 1923 is 140,000 tons. Both shafts are being equipped to permit of a large output being obtained when fully developed. Up to 2,500 tons per day can be dealt with.

State Coal Mine 1923

Size, depth and fittings of shafts
Diameter of upcast, 19 ft. in the clear (i.e., inside the brick lining) ; depth to floor of seam, 263 ft.

Diameter of downcast 20 ft. in the clear, 265 ft. to floor of seam. Both shafts will be equipped to wind coal, air-locks being provided at the upcast for this purpose. Two being provided at the upcast for this purpose.

Two cages in each shaft, single decked, carrying two tubs, each having a carrying capacity of 30-35 cwt., will be fitted with wire rope guides. At present a temporary cage carrying one tub is in use. It is dealing with the output pending the putting-in of the permanent plant.

Thickness of Seam
The seam as usually worked. in the Lithgow coalfield is 5 ft. 10 in. to 6 ft. above which there is about 4 ft. of top coal. This latter, although inferior to the bottom coal, will be utilised by the railway commissioners. The dip is about 1 in 70 N.E.

Headgear, Boilers, Screens, Tipplers, etc
The headgears (pulley frames) are now being made in the commissioners workshops at White Bay. Height of upcast headgear, 60 ft. to centre of pulleys.

Height of downcast headgear 81 1/2 ft. to centre of pulleys; rolled steel joints 12 in. x 6 in. x 44 lb., will form the main legs, with 8 in x 6 in. x 35 lb. rolled steel horizontal bracings diagonally braced and stiffened with 6 in. x 3 in. x 1 in. T bars.

Net load to be lifted at each wind, 3 to 3 1/2 tons of coal. Diameter of pulleys 12 ft. 4 in. running on 6 in. diameter shafts.

Stables & Upcast Shaft
Downcast Shaft Erecting Downcast Shaft

At present three Lancashire boilers 30 ft. x 81 ft., and with 110 lb. working pressure have been installed, having been got from the dismantled Hetton colliery, (Carrington in Newcastle). In addition, one Thompson dish-ended boiler, 30 ft. x 8 1/2 ft., with 160 lb. working pressure is about to be installed. More of this type will be provided as the mine develops.

Winding Engines, Fan, Pumps, Haulage and Electric Plant.
A pair of engines 26 in. cylinders, 4 1/2ft. stroke, parallel drum, 10 ft. dia, has been installed at the upcast shaft. These were obtained from Hetton colliery. At the downcast shaft a pair of 24 in. cylinders, 4ft. stroke, with 10 ft. dia. parallel drum is being put into position. These were made by Walker Bros., of Queensland, and were purchased from the Brilliant Extended Gold Mining Co. of that state. They are of modern make, fitted with steam-reverse and steam and hand brakes, piston valve, etc.

A Sirocco fan, double inlet, 350,000 c. ft. capacity, has been obtained. It was formerly in use at the Otford tunnel (Illawarra railway) as a blowing fan. It is now being overhauled and converted into an exhaust, preparatory to being used at the mine. The connecting airdrifts will be fitted with reversing doors, etc., so that if necessary the air-current may be reversed.

Two small steam driven sets, each of 10,000 gal. per hr. capacity now deal with all the water. Later on these will be replaced by electrically driven sets of greater capacity.

Electric locomotives (trolley wire) are being considered, the physical conditions of the mine (no gas or dust) lending themselves to this method of haulage.

Electric Plant
A 210 k.w., 3 phase, 50 cycles, alternator is now in course of erection. It will be used for power and lighting underground, and the driving of fan, creeper chains, etc., on the surface.

Coal Cutters
It is not likely that these will be put in for general use. but two or three may be procured for the drivage of the five winning places which have to go through a narrow strip of land for 1 1/4 miles, before reaching the main area. If so, they will be electrically driven.

The seam being naturally damp and non-gassy, ordinary methods of blasting are practised and gelignite is chiefly used, detonated by fuse and cap.

A temporary screen of the old type deals with the present output, but tenders are being invited for the permanent screening plant, consisting of four revolving tipplers, four shaking screens, four picking belts, 60 ft. long, by 4 1/2 ft. wide, and a rubber belt to convey the small coal from the four screens. Coal breakers will also be installed to reduce the lump coal to 4 in. cubes suitable for loco use. About 50 per cent of the output will be so treated. Ordinarily the seam yields 68 to 70 per cent of lump coal over a one inch meshed screen.

Erecting Screening Plant

Storage Dam
Owing to the nature of the sub-soil and the contour of the land, large storage dams are not advisable. Concrete reservoirs or tanks will be built, into which water will be pumped from an inset in the shafts, tapping the supply contained in the overlying shingle. This water is of good quality for boiler feed purposes and the supply is ample and permanent.

Branch Railway
This branches off the main western line near Eskbank station, and is about 1 1/4 miles in length, terminating with the usual colliery sidings for storage of wagons laden and unladen

The manager of the mine is Mr. Frederick Hemmingway, and Mr. Wm. McGhee, late of Sydney Harbour Colliery (Balmain), is the engineer.

From Chemical Engineering and Mining Review of 5 February 1923.