New Zealand Steel
| Industry | Steel manufacturing |
|---|---|
| Founded | 1965 |
| Headquarters | Glenbrook , New Zealand |
Area served | New Zealand and export markets |
| Products | Steel (650,000 tonnes annually) |
Number of employees | 1,350 |
New Zealand Steel Limited operates the Glenbrook Steel Mill, situated approximately 40 kilometres south of Auckland in Glenbrook, New Zealand. Established in 1968 and commencing operations in 1969, this facility manufactures 650,000 tonnes of steel annually, serving both domestic markets and exports. It fulfills more than 90% of New Zealand’s steel requirements, with the balance produced by Pacific Steel, a recycling plant located in Ōtāhuhu, Auckland.
The mill maintains a connection to the national rail system through the Mission Bush Branch railway line, enabling daily shipments of coal, lime, and finished steel products. Glenbrook employs around 1,150 permanent staff alongside 200 semi-permanent contractors.
A distinctive feature of New Zealand Steel is its reliance on ironsand as the main ore source. Given ironsand’s low grade and presence of impurities, the mill utilizes specialized processes and equipment that are unique within the steelmaking industry.
History
The ironsand deposits along the west coast beaches of New Zealand’s North Island, stretching from Kaipara Harbour to Whanganui, are rich in titanomagnetite. Between the late 1800s and the 1950s, numerous attempts to smelt steel from these sands were unsuccessful, largely due to technical challenges such as viscous slag that clogged machinery. In 1954, the Department of Scientific and Industrial Research initiated studies into ironsand smelting, which led to the creation of the NZ Steel Investigating Company in 1959 under the Iron and Steel Industry Act.
New Zealand Steel Limited was formed by the government in 1965 and began building its Glenbrook mill in 1967. The site was chosen for its closeness to the Waikato North Head ironsand mine and Huntly Power Station. Commercial production started in 1968 using imported feed coil to supply steel to domestic and Pacific Island customers. The company developed a direct reduction method that transformed iron oxide from ironsand into metallic iron, culminating in 1970 with facilities capable of producing billets for both local consumption and export. Subsequent expansions included a pipe manufacturing plant in 1972 and a prepainting line added in 1982, achieving an annual production capacity near 300,000 tonnes.
After several years of operating at a loss throughout the 1970s, New Zealand Steel introduced a more efficient iron extraction technique in 1981 that allowed for Glenbrook’s expansion. During New Zealand’s Think Big industrial development period, the mill underwent significant upgrades. In 1987, Equiticorp acquired New Zealand Steel but collapsed following the 1987 stock market crash. Ownership then transferred in 1989 to Helenus Corporation—a consortium including Fisher & Paykel, Steel & Tube, ANZ Bank, and BHP. By 1992, BHP had secured an 81% majority stake after purchasing shares from Fisher & Paykel and Steel & Tube. The company was renamed BHP New Zealand Steel Limited before reverting to New Zealand Steel in 2002 when BHP Steel rebranded as BlueScope on the Australian Securities Exchange.
On 21 May 2023, Prime Minister Chris Hipkins announced government support of up to $140 million aimed at cutting Glenbrook’s coal usage by half and lowering carbon emissions through installation of an electric arc furnace dedicated to scrap metal recycling.
The ore
The ironsand is extracted from an opencast mine located at Waikato North Head. Once mined, it is combined with water to form a slurry and then conveyed through an 18-kilometre pipeline to the processing mill. Each year, about 1.2 million tonnes of this ironsand ore are transported, with the total reserves believed to surpass one billion tonnes.
The processes
At Glenbrook's ironworks, the production setup includes four multiple hearth furnaces, four rotary kilns, and a pair of melters. The rotary kilns perform direct reduction of the ore into metallic iron, a method that differs significantly from the blast furnace technique typically employed in other steel plants.
Given the ore's elevated vanadium levels, extracting and removing vanadium is a crucial part of the steel manufacturing cycle. The ironsand also contains elements such as aluminium, manganese, and titanium. The oxidation of molten metal and elimination of impurities take place in a basic oxygen steelmaking unit utilizing the Klöckner Oxygen Blown Maxhütte (KOBM) method, which is distinctive for injecting oxygen both from the top and bottom of the converter—contrasting with conventional facilities that introduce oxygen solely from above.