THE IRON INDUSTRY.

Hawera Star, Volume XLV, 10 February 1926, Page 7

THE IRON INDUSTRY.

ONAKAKA ORE FIELDS.

WORKS FIRMLY ESTABLISHED

THE OUTLOOK ENCOURAGING

At the Dominion Mining Conference, which was held in Dunedin recently, Mr. J. -a. Lcggo, in the absence of Mr. J. A. Heskctt, presented an interestin'l' paper on the “New Zealand Iron Industries.” In apologising for Mr. Haskett’s absence, Mr. Leggo explained that he wds unablo to be present owing to his being the only man able to cope with any unforseen emergency which might arise at the works. ” He was pleased to say that the Onakaka iron works, after having passed through many vicissitudes, was at last on a fairly firm foundation, and had already distributed throughout the Dominion some :1000 tons of very excellent iron which had won glowjng reports from everyone who had used it. He instanced the case of the Northern Shipping Company, which had had a new cylinder case from New Zealand iron. The company luul stated that it had never had a better cylinder. It was gratifying, proceeded Mr. Leggo, to note that the Government and the Minister had given the scheme a particularly fair hearing, and that the company' was now receiving a bonus ot ■JOs per ton which was a considerable help. In time, the company hoped to do without this bonus, and even now, outside it, a small profit was being shown. Employment was being provided by the establishment of this now industry, and instead of the money going out of the country, it was being circulated in the Dominion. Thus, the money which the Government was spending was well spent. Nearly every other country received assistance, and the ironworks in India, which were the great thorn in the company’s side, were obtaining a 33 1-4 per cent, bonus on their product. Yet with all India’s wen Ith, concluded Mr. Leggo, the Onakaka Company was selling a few shillings cheaper than India, and 22s cheaper than Great Britain. An important step has been made in establishing an industry of great importance to the Dominion. Although New Zealand did not absorb more than 11.000 tons of pig-iron per annum, the whole of this trade was supported by imported iron, leaving the consumer at the mercy of shipping strikes and other contingencies, such as the late war, when pig-iron was at a premium. The Onakaka Iron and Steel Company was formed with'the expressed intention of manufacturing pig-iron from the iron ore deposits at Onakaka, which were a portion of the iron ore deposits situated near the foreshores of Golden Bay, in the north-western portion of the South Island, being almost one mile and a half from the sea shore, and running almost parallel to the coast. The deposit exists as a cap of iron ore on a hill extending approximately five miles, and includes the Para Para leases on the northern end and the Onakaka leases on the southern end; also the Tnkurua block, which lay midway between the two leases. The hill gradually rose from sea level at the northern end to about 1500 ft at the extreme southern end of the Onakaka lease, and the hill-top varied in width from about five to 15 chains, the deposits being broken in a number of places on the ridge, where limestone and at times quartz replaced the iron ore.

On the Onakaka lease limestone replaced the iron ore, and on the ParaPara lease quartz predominated where the iron deposit was interrupted. The depth of iron ore has been proved at the Para Para end. to exist 200 ft below the surface, by means of long tunnel drives. At Onakaka slips that were frequent on the slopes of the hill had exposed iron ore bodies 400 ft below the crest, the iron content of the ore exposed at 400 ft being low, and approximately 35 to 40 per cent, iron, the iron being replaced by silica. Where the ore existed there was no over-burden, and the outcrop was broken only by the limestone deposits cropping up between heavy bodies of iron ore. The limestone deposits rail at right angles across the hill, and extend approximately five chains in length, by 10 chains in width, and to a known depth of 900 ft. The amount of iron ore in sight represented many million tons, and what appeared a very safe estimate was 20,000,000 tons of high grade ore, and a considerably greater quantity of lower grade, running between 30 and 40 per 'cent. iron. The limestone used for fluxing was very conveniently situated, being quarried and handled alongside the iron ore face, the quarries being 3100 ft above the blast furnace and plant. The irun ore and limestone were conveyed by a monocable aerial tramway one mile and a half long to the bins, which were situated on a hill at the back of the blast furnace foundations, ami once the line was started there was sufficient weight in the full buckets to maintain the speed, which was further controlled by hand brakes, :if necessary, by the ,boy employed to right the buckets after they had tipped fhe ore or limestone automatically into the crusher in which the ore and limestone were crushed to 2Ain., after which they were conveyed by an 48in. rubber conveyor belt to their respective Uins, which were substantially constructed of reiuforced concrete. Six or seven tons of molten iron were tapped every six hours and allowed to rim ■ 50ft down a main runner, where it was split into two channels and fell into cast-iron moulds arranged on bearers sitting on wheels, which were hauled by a substantial friction winch at the speed desired to suit the flow of metal. When the metal sets in fhree to four minutes’ time, the moulds .were hauled on top of a gantry and capsized. where the pig-iron was delivered into a stack ready for shipping from the wharf, which was built of local timber, and has been erected two years.

Plenty of water was available •at a pressure of 11011) per equate inch, and Pclton wheels were used wherever necessary. Water was brought by a wooden flume three-quarters of a mile along the hillside mid delivered into a ].3in pine line, and thus conveyed a further three-quarters of a mile to the works. A well-equipped laboratory where daily analysis of pig-iron was undertaken facilitated the control _of the furnace, the main analysis being the determination of silicon and sulphur. There was an abundance of limestone and dolomite within the vicinity of the works, and the limestone being used was the deposit adjacent to the ore deposit, ayid although somewhat high in eiliea was handled very cheaply. Dolomite for steel furnace lining, was located near the Mount Burnett coal field, about 10 miles from Onakaka and about one mile from the foreshore of Golden Bay, and was easily accessible. It existed in a massive cliff formation, extending over a considerable area, with the face of the cliff hundreds of feet in height.

The coal measures within the vicinity were faulted and lenticular, and no serious attemjjt had been made to work them of recent years. There was quite a number of seams ranging from three feet to five feet in thickness, with occasional bands of stone, which came in and went out at various points. The coal was excellent cooking coal, and easy of access in some instances, but not'so in other cases.

'Pile future prospects of the industry appeared promising. The present outlet for the pig-iron produced was the Dominion market, and with a modern plant capable of producing from 300 to 400 tons of pig-iron per day,. New Zealand should produce a pig-iron at a cost that would allow it to compete with other exporting countries, particularly to markets on the Pacific coast of America. Freight prices from New Zealand to San Francisco encouraged this belief, being less than coastal freights in New Zealand from Onakaka.