Mount Isa Mine Early Infrastructure

Robert Lawlor held the 2.5 hectares (6.2 acres) Crystal Lease at Top Camp on the new Mount Isa field when the government geologist, EC Saint-Smith, inspected the area in September 1923. This lease was consolidated into Mount Isa Mines holdings by the end of 1924 but Lawlor's Shaft remained as the major access point to ores in the Rio Grande lode during the exploration and ore proving phase (1925-9). The headframe and ancillary buildings were featured in a photograph in the Queensland Government Mining Journal, 15 August 1929.[1]

In 1930 the Rio Grande mine was described as being served by the three compartment vertical Lawlor Shaft, from which, at a depth of 54.4 metres (178 ft), a crosscut in the hanging wall cuts through the lode of sulphide ore. Diamond drilling had already proved persistence of the ore to a depth of 305 metres (1,001 ft).[1]

It is not known when the Lawlor Shaft stopped operating but the King's Cross area of the settlement developed nearby and would have constrained mining operations. During the Second World War it was used for copper extraction.[1]

Urquhart Shaft and Headframe, 1932

Before Russo-Asiatic's engineers had visited the field, Corbould and his geologists decided that separate shafts should penetrate each ore-body and a railway should carry the ore from the shaftheads to a central treatment plant in the valley to the north. After a year of diamond drilling however, the ore-bodies were found grouped so closely, that they could be worked cheaply by use of an underground railway linking them to central shafts. Charles Mitke designed the Man and Supply shaft to take all men and materials underground and the Urquhart shaft to hoist the ore and pump the water.[1]

Mitke's plan transferred the main ore shaft and treatment plant to the town side of the long ridge, which divided the struggling township on the river flats from the previous centre of mining activity in the valley. Mitke supervised the sinking of the Urquhart shaft in 1929. Work proceeded simultaneously with the service shaft and development shafts in the Black Rock and Rio Grande ore-bodies, but was not completed at the time of a ministerial inspection in April 1930. The Urquhart shaft had hit an underground reservoir and was never continued to the planned depth.[1]

The Urquhart Shaft and Headframe were erected during 1930-31 and the ore produced had been smelted into lead bullion for shipment overseas by the official opening of the Mount Isa Mines complex by the Hon. Ernest Atherton, Minister for Mines, on 15 June 1931. The Urquhart shaft, which went down vertically for 0.5 miles (0.80 km), carried 3,000,000 long tons (3,000,000 t) of ore and rock each year. It operated for over thirty years until the biggest shaft on the Mount Isa field, then known as the K57 ore shaft, was opened in 1963.[1]

Mount Isa Mine Power Station, from W, 2003

From mid-1927 the technical management of Mount Isa Mine was in the hands of the Urquhart group (formerly known as the Russo-Asiatic Consolidated). With their increased capital they set about developing the "most modern mine of the age." The initial power house of Corbould's company was replaced by the steel framed power station consisting of a coal-fired boiler house and a generator house, designed by JM Callow in 1928 and located at the base of the Mount Isa Mine ridge overlooking the new tent settlement on the bank of the West Leichhardt River. The power station was operational by 1931 and a photograph of it appeared in the Queensland Government Mining Journal on 15 July 1931, which described the Ministerial opening of the new mining plant. It was described as having "twin chimneys rising like black cigars above a roof of dazzling iron".[1]

The powerhouse supplied electricity to the town and its houses as well as to the mine until the opening of the Mica Creek power station. In 1951 the powerhouse was extended to supply the new copper smelter. When the Mica Creek power station came into operation supplying electricity, the mines power station was adapted to supply compressed air for the entire mine operation. It continues to fulfill this function.[1]

From March 1923 when JC Miles discovered the lead outcrops of Mount Isa, shortage of water was identified as a "temporary disability" for the new field. Small soaks were opened in the bed of the Leichhardt River at both Top Camp and Lower Camp settlements. This appears to have been the period when the Experimental Dam was constructed, with a weir built at the entrance to a narrow gully, known as Hidden Valley, just south of the mine. The original stone wall of the weir was later raised with a form-cast concrete section. William Corbould of Mount Isa Mines knew that the treatment works would be greedy for water and EHR Greensill, a surveyor, recommended damming the gorge of Rifle Creek, 32 kilometres (20 mi) south of the mine. The Rifle Creek Dam was constructed by mid 1929 and a pipeline laid to Mount Isa, which became operational by 1930. Presumably from this time, the Experimental Dam ceased to function as a water supply augmenting the bores, which had been sunk. It was subsequently used for recreational purposes and there is a photographic record of a swimming carnival there about 1929.[1]

The remaining evidence of the Winding Plant consists of a partly intact two-cylinder steam winding engine without drums, manufactured by May Brothers Engineers of Gawler, South Australia, resting on concrete mounts (20.7325°S 139.4791°E / -20.7325; 139.4791 (Lawlor Shaft and Winding Plant)). Adjacent and to the south of the engine are a further two concrete foundations, possibly for an air compressor. A return flue boiler is situated further south in line with the winding engine. The iron chimney of the boiler lies alongside. The entrance to the Lawlor Shaft, which is now secured with a grid, is located east of the winding plant within a wire mesh security fence. There was no apparent evidence of headframes bases near the shaft. Between the shaft and the plant is a low raised earth surface indicating the extent of the winding shed and containing concrete mounts with machinery bolts and the concrete base for an iron chimney. The remnants of a mullock dump are located south of the mine shaft. The place is situated alongside the main mine road and adjacent to the company's former residential and community retail area known as King's Cross.

An intact steel headframe of asymmetrical design is located over the Urquhart shaft (20.7259°S 139.4816°E / -20.7259; 139.4816 (Urquhart Shaft and Headframe)). The headframe, occupying a hilltop position, is a community landmark and a symbol of Mount Isa Mines Limited and the City of Mount Isa. Headframe steelwork is attached to concrete foundations. The Urquhart headframe steelwork bears the name of the manufacturer, F Rodingham Iron & Steel Co Ltd., England. The concrete mounts of the original development headframe winding plant survive beneath the main structure. As the former main ore haulage shaft, the headframe is equipped with a large steel ore bin, which emptied directly into a primary crusher. The jaw crusher plant has been removed but the concrete structure of the crusher remains. From here the ore was conveyed to the three No.1 Concentrator mills.[1]

The Urquhart shaft's Uskside Winding Engine, which was housed in a shed immediately to the north of the headframe, has been removed from the site and installed at the "Outback@Isa Explorers Park" tourist facility in the town. The original corrugated iron winding shed which had been replaced by more recent ribbed steel sheets on the former frame and concrete surface, has also been removed from the site.[1]

The mine power station is located at the eastern base of the Urquhart Shaft hill (20.7280°S 139.4830°E / -20.7280; 139.4830 (Mount Isa Mine Power Station)). The power station forms a two-level complex comprising two sections, a boiler and furnace house on the eastern side and a turbine-generator powerhouse on the western side. The external appearance of both sections has remained comparatively unchanged since construction although substantial extension and adaptation of internal structure and plant have taken place with the development of the mine. The power station was initially coal-fired. The boiler house now contains natural gas and oil-fired furnaces, and waste-heat boilers which powered compressors to produce compressed air for the entire mine operation The power house which is a long steel framed corrugated iron clad building aligned north south has been substantially renewed and re- equipped since the 1950s. The original central third of the powerhouse remains structurally intact. This section originally housed Nos.1 and 2 turbo-generators. No.3 turbo generator (made in England by The General Electric Co Ltd., Witton, Birmingham) was installed in line north of No.2 in 1936 to replace No.1 generator after it blew up. No.2 generator has since been removed leaving No.3 as the only surviving early generator plant. No.3 plant comprising a General Electric alternator and turbine generator is coupled to a water-tube condenser unit (manufactured by Hick Hargreaves & Co Ltd., Bolton, England) situated beneath. The northern and southern sections of the powerhouse contain compressors installed in the 1950s. Mine power is now drawn from Mica Creek power station.[1]

Experimental Dam wall, showing raised area of wall, from W, 2003

The dam is constructed as a curved stone overshot weir, with later form-cast concrete additions above, at the entrance to a narrow gully of Kennedy Creek at the southern end of the Mount Isa Mine tailings and seepage ponds (20.7402°S 139.4720°E / -20.7402; 139.4720 (Mount Isa Mine Experimental Dam)). The wall shows the height of original construction and of two subsequent extensions in height and width. The original section is of rendered stone, initially rising an estimated 5 metres (16 ft) above the original valley floor, assuming a current build-up of about 3 metres (9.8 ft) of silt. The 1 metre (3 ft 3 in) deep overflow was subsequently in-filled with roughly rendered stonework. The wall was later raised a further 2 metres (6 ft 7 in) with a form-cast concrete section constructed atop the original structure. The weir now stands 5 metres (16 ft) above the existing upstream silt level and is 23 metres (75 ft) in width.[1]

This Wikipedia article was originally based on "The Queensland heritage register" published by the State of Queensland under CC-BY 3.0 AU licence (accessed on 7 July 2014, archived on 8 October 2014). The geo-coordinates were originally computed from the "Queensland heritage register boundaries" published by the State of Queensland under CC-BY 3.0 AU licence (accessed on 5 September 2014, archived on 15 October 2014).