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20-535: New Zealand Steel Limited is the owner of the Glenbrook Steel Mill , a steel mill located 40 kilometres south of Auckland , in Glenbrook, New Zealand . The mill was constructed in 1968 and began producing steel products in 1969. Currently, the mill produces 650,000 tonnes of steel a year, which is either used domestically or exported. Over 90% of New Zealand's steel requirements are produced at Glenbrook, while

40-501: A blast furnace where the iron compounds in the ore give up excess oxygen and become liquid iron. At intervals of a few hours, the accumulated liquid iron is tapped from the blast furnace and either cast into pig iron or directed to other vessels for further steel making operations. Historically the Bessemer process was a major advancement in the production of economical steel, but it has now been entirely replaced by other processes such as

60-709: A rolling mill . Originally the minimill was adapted to production of bar products only, such as concrete reinforcing bar , flats, angles, channels, pipe, and light rails. Since the late 1980s, successful introduction of the direct strip casting process has made minimill production of strip feasible. Often a minimill will be constructed in an area with no other steel production, to take advantage of local markets, resources, or lower-cost labour. Minimill plants may specialize, for example, in making coils of rod for wire-drawing use, or pipe, or in special sections for transportation and agriculture. Capacities of minimills vary: some plants may make as much as 3,000,000 tons per year,

80-613: A continuous production campaign of several years duration. Even during periods of low steel demand, it may not be feasible to let the blast furnace grow cold, though some adjustment of the production rate is possible. Integrated mills are large facilities that are typically only economical to build in 2,000,000-ton per year annual capacity and up. Final products made by an integrated plant are usually large structural sections, heavy plate, strip, wire rod, railway rails , and occasionally long products such as bars and pipe . A major environmental hazard associated with integrated steel mills

100-571: A loss during the 1970s, until 1981 when a more optimised, commercially viable method for extracting iron was implemented, leading to an expansion of the Glenbrook facilities. In the Think Big era of New Zealand industrialisation , the mill was upgraded. In 1987, New Zealand Steel was acquired by Equiticorp. Equiticorp was bankrupted in the New Zealand sharemarket crash of 1987 . In 1989 New Zealand Steel

120-436: A slurry and transported to the mill by an 18 kilometre long pipeline . Approximately, 1.2 million tonnes of ironsand ore are delivered to the mill annually. The area is estimated to contain over a billion tonnes. Glenbrook's iron plant contains four multiple hearth furnaces , four rotary kilns , and two melters. The kilns directly reduce the ore to metallic iron. This process is unusual as most mills use blast furnaces for

140-457: A typical size is in the range 200,000 to 400,000 tons per year, and some old or specialty plants may make as little as 50,000 tons per year of finished product. Nucor Corporation , for example, annually produces around 9,100,000 tons of sheet steel from its four sheet mills, 6,700,000 tons of bar steel from its 10 bar mills and 2,100,000 tons of plate steel from its two plate mills. Since the electric arc furnace can be easily started and stopped on

160-462: Is a low grade ore with many contaminants, the mill's primary plants' operations and equipment are unusual. The west coast beaches of the North Island of New Zealand between Kaipara Harbour and Whanganui contain ironsand deposits rich in the mineral titanomagnetite . From the late 19th century to the 1950s, there were many unsuccessful attempts to smelt steel from the ironsands. A prize offered by

180-416: Is sometimes used with scrap, to help maintain desired chemistry of the steel, though usually DRI is too expensive to use as the primary raw steelmaking material. A typical mini-mill will have an electric arc furnace for scrap melting, a ladle furnace or vacuum furnace for precision control of chemistry, a strip or billet continuous caster for converting molten steel to solid form, a reheat furnace and

200-640: Is the pollution produced in the manufacture of coke , which is an essential intermediate product in the reduction of iron ore in a blast furnace. Integrated mills may also adopt some of the processes used in mini-mills, such as arc furnaces and direct casting, to reduce production costs. A minimill is traditionally a secondary steel producer; however, Nucor (one of the world's largest steel producers) and Commercial Metals Company (CMC) use minimills exclusively. Usually it obtains most of its iron from scrap steel, recycled from used automobiles and equipment or byproducts of manufacturing. Direct reduced iron (DRI)

220-549: The Taranaki Provincial Government was never claimed, mostly due to problems encountered by people attempting to process the iron sand, such as a viscous slag of titanium carbides and nitrides that forms and blocks equipment when heat is applied to the sand. In 1954, the Department of Scientific and Industrial Research began investigating smelting from the ironsands. In 1959, The New Zealand Government established

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240-434: The basic oxygen furnace . Molten steel is cast into large blocks called blooms . During the casting process various methods are used, such as addition of aluminum , so that impurities in the steel float to the surface where they can be cut off the finished bloom. Because of the energy cost and structural stress associated with heating and cooling a blast furnace, typically these primary steel making vessels will operate on

260-781: The NZ Steel Investigating Company under the Iron and Steel Industry Act 1959 as a vehicle for the investigations. New Zealand Steel Limited was incorporated by the New Zealand Government in 1965. In 1967, construction started on a mill at Glenbrook. Glenbrook was chosen as the site due to the area's proximity to the Waikato North Head ironsand mine and Huntly Power Station . Commercial operations began in 1968, with imported feed coil being used to produce steel for domestic and Pacific Island markets. The company pioneered

280-408: The New Zealand Government would provide funding of up to $ 140 million for an initiative to halve the consumption of coal at the Glenbrook plant and reduce carbon emissions. The project involves installation of an electric arc furnace to replace coal as the heat source for recycling scrap metal. The ironsand ore is mined at an opencast mine at Waikato North Head . The ironsand is then mixed to form

300-463: The converter (Klöckner Oxygen Blown Maxhütte process, or KOBM converter), whereas oxygen is only blasted at the top of the converter in most steelmaking plants. Steel mill Since the invention of the Bessemer process , steel mills have replaced ironworks , based on puddling or fining methods. New ways to produce steel appeared later: from scrap melted in an electric arc furnace and, more recently, from direct reduced iron processes. In

320-399: The direct reduction process for reducing iron oxide (ironsand) into metallic iron. This culminated in the commissioning in 1970 of iron and steelmaking facilities to produce billets for domestic and export markets. Expansion continued with the commissioning of a pipe plant in 1972 and a prepainting line in 1982. Total output at this time averaged 300,000 tonnes a year. The steel company ran at

340-648: The late 19th and early 20th centuries the world's largest steel mill was the Barrow Hematite Steel Company steelworks located in Barrow-in-Furness , United Kingdom . Today, the world's largest steel mill is in Gwangyang , South Korea . An integrated steel mill has all the functions for primary steel production: The principal raw materials for an integrated mill are iron ore, limestone, and coal (or coke). These materials are charged in batches into

360-429: The reduction process. In the steelmaking plant, vanadium recovery and removal is done due to the high vanadium content of the ironsand ore. The sand also contains aluminium , manganese and titanium . Oxidation of the molten metal and contaminants is achieved by a basic oxygen steelmaking facility. The process used in the converter is the second unusual piece of equipment: oxygen is blown on both top and bottom of

380-529: The remaining volume is produced by Pacific Steel, a steel recycling facility in Ōtāhuhu , Auckland. The mill is served by the Mission Bush Branch railway line , which was formerly a branch line to Waiuku . Coal and lime trains arrive daily. Steel products are also transported daily. The mill employs 1,150 full-time staff and 200 semi-permanent contractors. New Zealand Steel is notable due to its unique utilization of ironsand as its ore . Because ironsand

400-584: Was acquired by Helenus Corporation, which consisted of Fisher & Paykel , Steel & Tube, ANZ Bank and BHP . In 1992, BHP took up a controlling interest with an 81% shareholding by acquiring the shares of Fisher & Paykel and Steel & Tube. The company was initially renamed BHP New Zealand Steel Limited, then in 2002 was renamed New Zealand Steel when BHP Steel was listed on the Australian Securities Exchange as BlueScope . On 21 May 2023, Prime Minister Chris Hipkins announced that

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