Iron is one of the most available elements in the earth’s crust at about 4.6% by mass. Australia has a rich mining history and some of the top mines and companies in the world. Commonly occurring iron minerals and deposits of iron ores of are hematite, magnetite and goethite, which contribute approximately 99% of the whole iron constituting minerals. Significant iron ore mines are located in Western Australia and Australia’s iron ore production in million metric tons value over the past decade has shown a positive growth trend with the sharpest rise in the 2010 to 2015 period. The sharpest rise in iron ore production was a result of the boom in iron ore exploration in Australia which peaked in 2012 and by far China has been the leading export destination for Australian iron ore. On the flipside, the net value of iron in Australia over the past decade has shown a consistent decrease ever since the apex was reached in 2015. The aim of the article is to extensively highlight iron ore in Australia whilst deliberating on what it is, the different type available, where it is mined in Australia and the importance of dust control at the source of iron ore mining activities in relation to Global Road Technology products for dust control for iron ore mining in Australia.
How is iron ore formed?
The formation of iron ore is attributed to geological processes of crystallization from silicate solution. Denser ferrous materials precipitated to the base of the ocean which resulted in the formation of a final rock mass restricted to certain areas that iron rich than others. Deposition of iron-bearing minerals and gangue minerals especially silica could possibly leach out by water solution when surface water descended, and underground water ascended through rock strata. Another possibility could be concentration of iron bearing minerals by precipitation from water reservoirs, lakes, seas, rivers as result of chemical and bacterial activity. Goethite mineral is enriched along with hematite ore during the process of beneficiation, which results in an increased percentage of loss on ignition in the concentrate. Oxidation of lower grade oxides, such as magnetite to hematite takes place in the upper zone of ore bodies. These minerals are deposited on the sea floor in great abundance forming the banded iron formations and the rocks are banded because the iron minerals are deposited in alternating bands with silica and in some cases shale. Typically, banded iron formation consists of repeated, thin layers of silver to black iron oxides, either magnetite (Fe3O4) or hematite (Fe2O3), alternating with bands of shale and cherts which are often red in color.
Global and national deposits
Banded iron formations account for more than 60% of global iron reserves and can be found in Australia, Brazil, Canada, India, Russia, South Africa, Ukraine and the USA. Goethite ore is one of the most common and the third most abundant source of iron, it is an oxyhydroxide (α–FeOOH) and is formed in the orthorhombic crystallographic system under oxidizing conditions as a weathering product of iron bearing minerals. The ores may contain aluminium oxide, manganese oxide, calcium oxide and silicon oxide as impurities within their matrix and do have varying chemical compositions. Australia has large reserves of pisolitic limonite ores, and the ore contains about 10% by weight combined water. Iron ore in Australia is mainly found in rocks that are more than 600 million years old. The mineralogy of iron ores in Australia is predominantly martite which is hematite that has replaced primary magnetite. Other classifications of iron ores includes hematite which is colored black to steel or silver-gray, brown to reddish brown, or red. While forms of hematite vary, they all have a rust-red streak and their further classification based on chemical purity, hardness and density are as follows, hard ores, lateritic ores, flakey ores and soft ores. Finally, the mineral magnetite is an oxide of iron which is ferromagnetic and attracted to a magnet. Magnetite ore consists of both ferrous and ferric iron and differ from most iron oxides in that it contains both divalent and trivalent iron. It is black or brownish-black with a metallic luster.
Iron ore in production in Australia
BHP initiated iron ore mining in South Australia in 1903, initially for flux at the Port Pirie lead smelters but later steel production at Newcastle in 1915 and primarily as a way to provide for its future beyond Broken Hill. The two largest iron ore producers in the world are Rio Tinto and BHP Billiton with operations primarily in Australia. Australia has the largest reserves in terms of iron ore content and boasts as the major iron ore exporter for more than 40 years. The iron ore export industry in Australia is dated back to the lifting of the export embargo in the 1960s which followed the discovery and development of large iron ore resources in the Pilbara region of Western Australia which accounts for about 95% of Australia’s iron ore production. The major producers of iron ore in the Pilbara region are BHP Billiton, Rio Tinto and Fortescue Metals Group with smaller contributions from Atlas Iron, Hancock Prospecting at its Hope Downs mine and BC Iron. Other producers include Mount Gibson Iron and Gindalbie Metals Ltd in the Midwest region north of Perth for sinter fines and magnetite concentrate and Cliffs Natural Resources in the Yilgarn region east of Perth for sinter fines. Arrium Mining on the Eyre Peninsula in South Australia (Whyalla) produces magnetite pellets whereas Grange Resources in Tasmania exports magnetite pellets with minor contributions from Ernerst Henry Mining and Mt Moss Mining in Queensland.
Are environmental regulations, health and safety concerns or potential profit loss a concern right now?
All the iron ore mines in Australia are open cut and the ore is usually extracted by conventional drilling and blasting methods. These methods generate a lot of fugitive dust which is both inhalable and respirable metalliferous dust. Although Australia produces direct shipping ores, their transport from pit to port generates a significant amount of dust from processes such as stockpiling, veneering, haul road transportation, conveyor belt transfers amongst many other processes. Stages such as crushing and screening produce lump and sinter fines products which are stockpiled and blended on-site or at the port prior to export. The new more complex ore types often require additional processing to achieve the required grade which requires various nonmagnetic physical separation methods such as scrubbers, jigs, spirals, hydrocyclones, cyclones and heavy medium drums.
How can GRT assist iron ore operations?
Through their different dust control products Global Road Technology offers GRT Haul-Loc for iron ore mine haul roads, GRT Ore-Loc for live and dead iron ore stockpiles, GRT Activate and GRT Ore-Loc for hydrophobic iron ore materials during transportation from metalliferous mines to ports for export, and GRT EnviroBinder for post iron ore mining rehabilitation of metalliferous mines.
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REFERENCES
- Bhagat, R.P. 2019. Agglomeration of Iron Ores. Taylor & Francis Group. 1-441.
- Lu, L. 2015. Iron Ore – Mineralogy, Processing and Environmental Sustainability. Woodhead Publishing Series in Metals and Surface Engineering. 66. 1-640.
- Mudd, G.M. 2007. An analysis of historic production trends in Australian base metal mining. Ore Geology Reviews. 32. 227-261.
