New Zealand Steel

New Zealand Steel Limited is the owner of the Glenbrook Steel Mill, the 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 domesticity used or exported.[1][2] Over 90% of New Zealand's steel requirements are produced at Glenbrook while the remaining volume is produced by Pacific Steel, a steel recycling facility in Otahuhu, 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.

Glenbrook Steel Mill
Glenbrook Steel Mill from the mill's lookout
Glenbrook Steel Mill location in New Zealand
Built1968
LocationAuckland, New Zealand
Coordinates37.21°S 174.74°E / -37.21; 174.74
The Glenbrook Steel Mill from the air.
The Glenbrook Steel Mill's iron plant.

New Zealand Steel is notable due to its unique[1][2] utilization of ironsand as its ore. Because ironsand is a low grade ore with many contaminants, the mill's primary plants' operations and equipment are unusual.[2]

History

The west coast beaches of the North Island of New Zealand, between Kaipara Harbour and Whanganui, contain ironsand deposits rich in the mineral titanomagnetite.[3] From the late 19th century to the 1950s, there were many unsuccessful attempts to smelt steel from the ironsands. In 1954, the Department of Scientific and Industrial Research began investigating smelting from the ironsands. In 1959, The New Zealand Government established the NZ Steel Investigating Company under the Iron and Steel Industry Act 1959 as a vehicle for the investigations.[4]

New Zealand Steel Limited was incorporated by the New Zealand Government in 1965. In 1967, construction started on a mill at Glenbrook.[5] Commercial operations began in 1968, with imported feed coil being used to produce steel for domestic and Pacific Island markets. The company pioneered 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.

In the Think Big era of New Zealand industrialisation, the mill was upgraded. In 1987, New Zealand Steel was acquired by Equiticorp. However, Equiticorp was bankrupted in the New Zealand sharemarket crash of 1987. In 1989 New Zealand Steel 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, but in 2002 it was renamed New Zealand Steel when BHP Steel was listed on the Australian Securities Exchange as BlueScope.[5]

The ore

The ironsand ore is mined at an opencast mine at Waikato North Head.[1] The ironsand is then mixed to form a slurry and transported to the mill by an 18 kilometre long pipeline.[2] Approximately, 1.2 million tonnes of ironsand ore are delivered to the mill annually.

The processes

Glenbrook's iron plant contains four multiple hearth furnaces (MHFs),[6] four rotary kilns, and two melters. The rotary kilns reduce the ore to metallic iron. This process is unusual as most mills use blast furnaces for this reduction process.

In the steelmaking plant, vanadium recovery and removal is done due to the high vanadium content of the ironsand ore.[2] 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 the mill operates : oxygen is blown on both top and bottom of 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.

References
  1. "Glenbrook Steel Site Operations". New Zealand Steel Limited. 2011. Archived from the original on 6 January 2014. Retrieved 21 February 2012.
  2. John Green and Jeremy Batchelor (2008). The Manufacture Of Steel. The New Zealand Institute of Chemistry.
  3. Templeton, Fleur (12 June 2006). "1. Iron – an abundant resource - Iron and steel". Te Ara Encyclopedia of New Zealand. Retrieved 4 January 2013.
  4. Templeton, Fleur (28 September 2010). "Iron and steel - Attempts to extract iron". Te Ara - the Encyclopedia of New Zealand. Retrieved 30 May 2012.
  5. "New Zealand Steel - History". New Zealand Steel Limited. 2011. Archived from the original on 26 February 2012. Retrieved 20 February 2012.
  6. "The science of steel". New Zealand Steel. Retrieved 18 September 2017.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.