Between 1920 and 1942, small-scale iron production was achieved in New Zealand, using deposits of limonite (a hydrated ferric oxide mineral) near Onekaka in the Nelson province. However, the size of this ore reserve was badly overestimated and in the late 1940s attention returned to the smelting of ironsands.
By this time, considerable expertise was available on the electric smelting of titaniferous ores. Laboratory work by the Norwegian company, Christiania Spigerverke, had shown that careful control of slag composition would achieve trouble- free smelting, and the DSIR used these results in conducting continuous smelting trials for the Department of Industries and Commerce at Onekaka in 1949.
F. C. Collin from the Norwegian firm, Elektrokemisk, supervised the trials. Power was provided by Nelsons Cobb Station to a simple 600- kilowatt furnace some two metres in diameter. Sintered ironsand was used with Waikato char as reductant and limestone and quartzite as fluxes, the quantities of which were defined by the Norwegian studies. No difficulties from slag thickening or viscosity were experienced but power consumption was higher than anticipated. These tests were an important advance towards the establishment of a New Zealand steel industry but confirmed Harbords conviction that electric smelting by itself could not provide an economic means of processing ironsand.
The New Zealand Steel Investigating Company
Fletchers Taharoa Venture
In 1955, William R.B. Martin, a research fellow at Victoria University, published a report on the potential of a New Zealand ironsands industry. He then worked with Fletcher Holdings Ltd, who in 1956 engaged the American company, Henry J. Kaiser, to carry out a feasibility study for a large electric-smelting steel plant near an extensive iron sand deposit at Taharoa, south of Kawhia Harbour on the North Islands west coast. However, owing to the remoteness of the site and the cost of constructing a harbour at nearby Albatross Point, the project lapsed.
Research continued at the DSIR. In 1954 Tom Marshall, who had participated in the Onekaka trial, visited the Christiania Spigerverke scrap-steel melting plant. His observations along with advice from F.C. Collin convinced him that New Zealand could make steel from scrap using an electric furnace and expand later into iron sand smelting. After consulting the Department of Industries and Commerce and the Reserve Bank, he approached Stewart R Lloyds and Fletcher Holdings who, in 1958, prepared a proposal for what was to become Pacific Steel. A Department of Industries and Commerce committee initially suggested that New Zealand did not produce enough scrap to support such a venture, but Fletchers called in a British expert, Dr T. P. Colclough, who provided evidence to the contrary. Pacific Steel was allowed to proceed.
Steelmaking A Strategic Industry
But the permanent head of the department, Dr William B. Sutch, regarded steel making as a strategic industry too important to be left entirely in the hands of a private company. He therefore instituted a second study, which led to the 1959 Iron and Steel Industry Act and the establishment of the New Zealand Steel Investigating Company. Minister of Industries and Commerce Phil Hollaway appointed Woolf Fisher as chairman of directors of the investigating company in 1960. Fisher made extensive use of experienced DSIR staff, including Ian D. Dick (technical director), Tom Marshall (metallurgist), Don S. Nicholson (mining engineer) and David Kear (geologist). He also employed the DSIR geophysics division (for drilling), as well as the services of other government departments and commercial organisations both in New Zealand and overseas.
The companys first priority was to survey the extent of New Zealands iron sand resources, since Ian Dick insisted that fifty years supply of raw materials should be proved. Investigations were conducted by DSIR scientists Don Nicholson and H. E. Fyfe, no doubt in ignorance of that carried out on behalf of Earnest Cull. They indicated extensive deposits (probably from Mt Egmont volcanic ash) between Wangaehu and Kaipara South Head. However the largest of these, at Lake Taharoa, was not easily accessible, while those at Muriwai and Wanganui were located at prime beach sites or under high-quality farmland. Other deposits, such as at Patea, were merely thin, wind-blown layers. The remaining sites of commercial interest were assessed in more detail in 1961.
Drilling at Raglan showed that deposit to be superficial, but drilling at Waikato North Head revealed an extensive deposit of high-grade material beneath a skin of low- grade wind-blown sand. This, together with the availability nearby of Waikato coal and the proximity of the Auckland market, promised economic advantages to offset the disadvantage of the small New Zealand economy.
A Site at Glenbrook
The selected industrial site, at Glenbrook on the Manukau Harbour, was within a sixty-kilometre radius of all three resources and near a surveyed canal route intended to provide a future connection to the Waitemata Harbour at Onehunga.
The problem remained of finding a technology to deal with a raw material that had foiled previous steel makers. Moreover, the selected process needed to take account of the highly volatile, low-ash, low-sulfur, sub- bituminous Waikato coal from Huntly.