<!-- Used power station infobox for location information -->
thumb|right|Glenbrook Steel Mill from the air
thumb|Glenbrook Steel Mill's iron plant
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 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 From the late 19th century to the 1950s, there were many unsuccessful attempts to smelt steel from the ironsands. A prize offered by 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 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.
The ore
The ironsand ore is mined at an opencast mine at Waikato North Head.
The processes
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 the reduction process.
In the steelmaking plant, vanadium recovery and removal is done due to the high vanadium content of the ironsand ore. 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 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.