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Deposit Synonyms
Ml 2927; Ml 4040; Ml 4041; Ml 4042; Ml 4044; Ml 4045; Ml 4046; Ml 5317; Pm 291; Rl 133; Rogues Gully
Mineral District
Deposit Summary
brown, fine grained, dense dolomite rock of the Cambrian Kulpara Dolomite. Operations commenced in 1939. Production from 1950-2013 >27Mt of which >150,000t was for the construction industry. Potential for large remaining resources.
Deposit Description
ARDROSSAN, large dolomite mining operation owned by Liberty Onesteel to supply flux in their steelmaking process. The quarry developed on a deposit of yellow-brown, fine grained, dense, crystalline, dolomite rock, being a dolomite phase of the basal sequence of the Cambrian Kulpara Limestone. The formation of dolomite may be largely structurally controlled forming in a shallow, S-plunging syncline, with the dolomite distribution bound to the east by the Ardrossan Fault (also the eastern limit of the pit). Within these stuctures the thickness of dolomite exceeds 300m, with the deepest part penetrated to 177m. The dolomite grades lateraly to the west into limestone (also the W limit of the pit). Sandstone, quartzite and grits underlie the dolomite. Within the area of quarrying the dolomite is close to the theoretical value of pure dolomite (21.86%MgO), with minor silica and alumina. The dolomite is widespread north of the quarried area, cropping out at intervals towards Kulpara, and with known thick sequences of the high-grade dolomite phase. Typical assay SiO2 0.5%, FeO 1%, A2O3 0.42%, MnO 0.26%, CaO 30.85%, MgO 20.55%, LOI 36.3%. The dolomite is yellow and buff coloured in the upper part becoming grey and less dolomitic with depth. The formation is intensely cracked in places, with earthy zones adjacent to faults common in the quarry. Conformable siliceous lenses are scattered throughout the sequence, which is characterised by fauna of archaeocyathids and brachiopods. Manganese oxide dendrites are common on joint planes.
Mining started in 1939. BHP purchased the mine in 1950 and made its first shipment in early 1953. Lump ore was mainly used locally as a flux in basic oxygen steelmaking at steelworks at Whyalla, Port Kembla and Newcastle. It was also used as a refractory material at the Whyalla Steelworks. There was significant tonnage exported to Japan.
Production by BHP commenced in 1950 at ~50,000 tpa, ramping up to 150,000 tpa. Production from 1950-2013 is estimated at >27 million tonne, dominantly for an industrial end use, minor production for use in the construction industry. Dolomite used for road seal aggregate was found to be suitable for surfacing in terms of hardness, particle shape and soundness. The relatively clean dolomite would have the potential to polish under traffic (low PSV) however for the relatively low rainfall environment and low traffic volume roads local to the area, performance could be considered as adequate.
Current operator is Arrium Mining, with recent production rate 10,000-100,000 tonne/annum, with a current capacity for annual production rates of 600,000 tonne. Quarry form is as a multibench quarrying operation developed over an area of more than 100 hectares. Resource estimate for 2013 pit area is 71Mtonne at 20.8%MgO, 30.2%CaO, 0.83%SiO2, 0.25%Al2O3, 46.4%LOI (losson ignition), 0.082%S, and 0.11%P. Additional resources likely for northern extensions to pit. Minor sand resource assessed south of the main pit in 1967.
Discovery Year
~ 1918
Commodities
Dolomite
Ore Minerals
Dolomite
Gangue Minerals
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