Iron Fact Sheet
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Iron (Fe) is one of the most abundant rock-forming elements, constituting about 5% of the Earth's crust. It is the fourth most abundant element after oxygen, silicon and aluminium, and after aluminium, the most abundant and widely distributed metal. Iron is indispensable to modern civilisation and people have been skilled in its use for more than 3,000 years. However, its use only became widespread in the 14th century, when smelting furnaces (the forerunner of blast furnaces) began to replace forges.
Iron ores are rocks from which metallic iron can be economically extracted. These rocks are usually found in the form of hematite (Fe2O3) or magnetite (Fe3O4). About 98% of world iron ore production is used to make iron in the form of steel. Iron ore provides the foundation for one of Australia’s major export industries.
Most iron ores mined today comprise the iron oxide minerals hematite, Fe2O3 (70% Fe); goethite, Fe2O3s H2O, (63% Fe); limonite, a mixture of hydrated iron oxides (up to 60% Fe); and magnetite, Fe3O4(72% Fe).
Most of the world's important iron ore resources occur in iron-rich sedimentary rocks known as banded iron formations (BIFs) which are almost exclusively of Precambrian age (i.e. greater than 600 million years old). BIFs occur on all continents. In many instances they are mined as iron ores, but most importantly they are the source rocks for most of the large high-grade concentrations of iron ore currently mined throughout the world.
In the Hamersley Province in the Pilbara district of Western Australia there are three main types of deposit: iron oxide enrichments within BIFs; iron oxides deposited along ancient, mainly Tertiary age river channels (palaeochannels); and iron oxide deposits formed from the erosion of existing orebodies (detrital iron ore deposits).
The BIF enrichment deposits comprising hematite and hematite goethite are the most important in regard to resources and production. The iron content of these ores varies widely and until recently most deposits needed to have an average grade of more than 60% Fe for mining to be commercially viable. However, some deposits can now have iron grades between 56-59% Fe and be commercially viable.
The palaeochannel deposits comprised of pisolitic limonite are the next in importance and are prized for their low impurities such as phosphorus. They are not as rich in iron as the BIF enrichment ores. Those mined usually contain 57-59% Fe.
Detrital iron ore deposits, including scree and canga deposits, are found downhill of the BIF enrichment deposits from which they have been eroded. They are usually easily recovered and have a grade of between 40-55% Fe. BIF enrichment deposits also occur elsewhere in Western Australia in the Pilbara (e.g. Yarrie), and the Yilgarn Block (e.g. Koolyanobbing) and in South Australia (e.g. Iron Duke, Middleback Range).
Numerous magnetite deposits of igneous origin or association occur in most States and uneconomic sedimentary sideritic (those containing the mineral siderite, FeCO3) iron ore deposits occur in Queensland and the Northern Territory.
Although iron ore resources occur in all the Australian States and Territories, almost 93% of identified resources (totalling 64 billion tonnes) occur in Western Australia, including almost 80% in the Hamersley Province, one of the world's major iron ore provinces.
In 2009 Australia's economic demonstrated resources (i.e. those that have been sufficiently tested by drilling and that could be economically extracted at current prices with existing technology) totalled 28 billion tonnes and ranked Australia second (with 17%) behind the Ukraine (18%).
As with most iron ore mines throughout the world, all the major Australian iron ore mines are open cut. The ores from the major mines in Western Australia's Pilbara region are hauled from working faces to crushing and screening plants using trucks that can carry over 300 tonnes. The ore is then transported for further treatment and blending to port sites in trains consisting of up to three locomotives and over 250 wagons. Trains of this size are over 2 kilometres long and contain loads in excess of 25,000 tonnes. There are two major Pilbara iron ore producers: BHP Billiton and Rio Tinto Ltd.
BHP Billiton manages the Mount Newman Joint Venture (Mount Whaleback plus three other nearby mines); the Yandi Joint Venture (Yandi/Marillana Creek mine); the Mount Goldsworthy Joint Venture (Yarrie mine); and the Mining Area C Joint Venture (C Deposit mine). It also owns the Jimblebar mine. The Mount Whaleback mine, 5.5 kilometres in length, has a width of up to 2 kilometres and will be mined until it reaches a depth of 0.5 kilometres. Products from these mines are transported by rail to Port Hedland for export and shipment to Australian steelworks. Most products are further crushed, screened and blended at the port.
Hamersley Iron Pty Ltd (100% Rio Tinto) operates the Mount Tom Price, Brockman 4, Paraburdoo, Channar, Eastern Range, Marandoo, Yandicoogina (or HIYandi) and Western Turner Syncline mines. The lump and fines ore products from the mines (lump ore size is 6.3 to 31.5 millimetres; maximum size of fines is 6.3 millimetres) are transported by rail to the port of Dampier for blending and rescreening before export. Rio Tinto (50%) and Hancock Prospecting (50%) operate the Hope Downs mine in the Pilbara.
Robe River Iron Associates (53% Rio Tinto) mines pisolitic limonite ore deposits at Mesa A along the Robe River. The ore is railed to Cape Lambert for crushing and screening and export as fines (limonite fines, including those from HIYandi above have a maximum size of 9.5 millimetres). Robe River also mines Marra Mamba ore at the West Angelas operation and rails the products to Cape Lambert for export.
The Fortescue Metals Group operates the Cloud Break and Christmas Creek mines which rail Marra Mamba ore to Port Hedland for export. Citic Pacific Mining operates the Sino Iron Project at Cape Preston which produces magnetite concentrates and pellets for export. Atlas Iron operate the Pardoo and Wodgina mines near Port Hedland. BC Iron operates the Nullagine mine and Moly Mines operates the Spinifex Ridge mine. Cliff Natural Resources mine iron ore at Koolyanobbing and rails products for export to the port of Esperance in WA. Cliffs also have a mine on Cockatoo Island in north west WA. Mount Gibson Iron Ltd operates the Tallering Peak , Extension Hill and Koolan Island iron ore mines in WA. Murchison Metals Ltd operates the Jack Hills mine which trucks hematite ore 540 km to the Port of Geraldton. Sinosteel Midwest Corporation produce direct shipping ore at the Koolanooka mine for export from Geraldton.
In South Australia, iron ore is extracted from the Middleback Ranges by OneSteel Ltd for export and also for use in iron and steelmaking at Whyalla. In Tasmania, magnetite ore mined at Savage River by Grange Resources is crushed, ground and concentrated, then pumped 85 kilometres as a slurry to Port Latta via a pipeline where pellets are produced for shipment. Territory Resources operates a mine at Frances Creek in the Northern Territory.
In various parts of Australia other iron ore deposits are mined on a small scale (50,000 - 100,000 tonnes a year), mainly for coal washing, mineral separation, cement manufacture, gas and water purification, fluxing and the manufacture of pigments. Such operations include Tallawang in New South Wales and Kara in Tasmania.
In 2009 Australia produced 394 million tonnes of iron ore of which 362 million tonnes was exported valued at $30 billion. Western Australia produced 97% of the total production in 2009. Australia is the world's largest iron ore exporter and, as a producer, ranks second (with 17%) after China (39%).
Concentration includes all the processes that will increase (upgrade) the iron content of an ore by removing impurities. Beneficiation, a slightly broader term, includes these processes as well as those that make an ore more usable by improving its physical properties (e.g. pelletising and sintering). Many of the iron ore mines employ some form of beneficiation to improve the grade and properties of their products. At Mount Tom Price, Paraburdoo and Mount Whaleback major concentrators have been constructed which enable low grade iron ores, including ores which have been contaminated with shale, to be mined and after upgrading, sold as high grade products. The operation of the concentrators has also increased the iron ore resources available at these mines.
Pelletising is a treatment process used for very fine or powdery ores. Pellets are an ideal blast furnace feed because they are hard and of regular size and shape. In Australia, concentrates pumped from Savage River are pelletised at Port Latta for shipment to domestic and overseas markets, and fine Middleback Range ores are pelletised prior to smelting in the Whyalla blast furnace.
Sintering is a process used to agglomerate iron ore fines in preparation for blast-furnace smelting, and is usually carried out at iron and steelmaking centres. It involves the incorporation of crushed limestone, coke and other additives available from iron and steelmaking operations. These additives include wastes extracted from furnace exhaust gases, scale produced during rolling mill operations, and coke fines produced during coke screening.
Pig iron is an intermediate step in the production of steel and is produced by smelting iron ore (commonly in lump, pellet or sinter form) in blast furnaces. Blast furnaces are located at Port Kembla and Whyalla. HIsmelt Corporation Pty Ltd has a Direct Reduced Iron (DRI) plant at Kwinana in WA that is currently on care and maintenance. The removal, by oxidation, of impurities in pig iron such as silicon, phosphorus and sulphur and the reduction in the carbon content, results in the production of steel.
Steel is produced at Port Kembla, Whyalla, Sydney, Mayfield and Laverton North. At Sydney (Rooty Hill), Mayfield and Laverton North, steel is produced entirely from the remelting of scrap iron and steel in electric arc furnaces (EAF). In 2009 Australian iron and steel production including recovery from scrap totalled 5.1 million tonnes which although locally significant is small on a world scale.
Although iron in cast form has many specific uses (e.g. pipes, fittings, engine blocks) its main use is to make steel. Steel is the most useful metal known being used 20 times more than all other metals put together. Steel is strong, durable and extremely versatile. The many different kinds of steel consist almost entirely of iron with the addition of small amounts of carbon (usually less than 1%) and of other metals to form different alloys (e.g. stainless steel). Pure iron is quite soft, but adding a small amount of carbon makes it significantly harder and stronger. Most of the additional elements in steel are added deliberately in the steelmaking process (e.g. chromium, manganese, nickel, molybdenum). By changing the proportions of these additional elements, it is possible to make steels suitable for a great variety of uses.
Steel's desirable properties, and its relatively low cost, make it the main structural metal in engineering and building projects, accounting for about 90% of all metal used each year. About 60% of iron and steel products are used in transportation and construction, 20% in machinery manufacture, and most of the remainder in cans and containers, in the oil and gas industries, and in various appliances and other equipment.