First steel produced from local ironsand

Iron and steel from local ironsand (titanomagnetite) was produced for the first time at New Zealand Steel’s mill at Glenbrook, near Waiuku, south of Auckland. Today ironsand (from the nearby Waikato North Head mine) and coal is used to produce about 600,000 tonnes of steel a year.

The ‘black sands’ of the west coast of New Zealand’s North Island were noted by the navigator James Cook in 1769. These ironsand (titanomagnetite) deposits have long been recognised as a rich reserve of metal ore. The ironsand is the product of rocks formed by volcanic activity in the Taranaki area 2.5 million years ago. In some places the ironsand deposits have formed dunes up to 90 m high.

Early European settlers were fascinated by the sands’ magnetic qualities. Early attempts to smelt iron from the ironsand met with little success. In the 1950s, with local and international demand for steel growing, renewed efforts were made to utilise this valuable resource for a home-grown steel industry. In 1959 the government established a New Zealand Steel Investigating Company to determine the technical and economic feasibility of manufacturing steel from local raw materials. New Zealand Steel Ltd was incorporated in 1965 and construction of the Glenbrook mill began in 1966. It was opened in 1968.

Glenbrook pioneered new techniques in the production of iron and steel. It has also undergone a number of changes as a result of passing from public to private ownership. The constant factor has been the mill’s use of rich North Island black sands.

Image: Ironmaking  (NZ Steel)