TARANAKI IRONSAND

Taranaki Daily News, 8 October 1921, Page 7

TARANAKI IRONSAND

ELECTRIC FURNACE SMELTING. PREMIER SEES TESTS. FUTURE POSSIBILITIES. (Wellington Posts Correspondent.) London, August 24. Mr. Massey’s visit to I Arlington lust week-end was primarily concerned with Taranaki ironsand. For some considerable time Messrs. Thomas Summerson and Song have taken an interest in this product of New Zealand, and they claim now that, given sufficiently cheap electricity, the conversion of the sands into pig-iron and steel would be a com tnercially payable proposition. A few weeks ago some 20 tons of Taranaki sand and 20 tons of Parapara ore were sent from New Zealand, and the High Commissioner had arranged for an expert to report on experiments which are being carried out this week. At the invitation of Mr. Robert Summerson,' the present head of the firm, Mr. Massey, while in Darlington, witnessed the first of these official tests and saw a quantity of the Taranaki ironsand converted into pig-iron. Already, however, the firm had had several trials, and were able to exhibit a number of steel castings made from the sand during the week previously. One of the greatest living authorities on steel, the eminent metallurgist, Mr. F. W. Harbord, is reporting on the tests in due course, and at present, therefore, it is not possible to make a definite statement of the results. Sufficient, however, was seen by the Prime Minister to convince him of the great commercial possibilities which exist in these raw materials. Mr. Massey also asked Mr. Evan Parry to go to Darlington and to give his opinion on the hy-dro-electric part of the scheme. Even for the mere layman, however, there was much to learn. Ocular demonstration convinced one the iron and steel produced were good. One saw the completed castings, and one saw the metal poured off a molten mass from the furnace, but there were other vital points with which one became familiar. OVERCOMING THE CHIEF DIFFICULTY.

There is nothing new about the process adopted by the firm for smelting the material. But instead of doing it in an ordinary blast furnace it is done in an electric furnace. Experiments in New Zealand hitherto have failed in one respect at least. The titanic acid in the iron sands had failed to liquify in a. blast furnace. It had not been possible, , therefore, to pour it off with the sing, and the consequence has been that the furnace has been choked, necessitating cooling off after three or four lots of metal have been poured off, and practically renewing part of the lining of [ the furnace. Iji the electric furnace there is sufficient heat to liquify the titanic acid, which pours off with the slag in the ordinary way. That seems to be the whole secret. For the result it is a matter of whether it is possible to obtain a cheap supply of electricity, for it is maintained that it would be necessary. to obtain the current at one-tenth of a penny per unit, or from £2 10s to £3 a horse-power per year, in order to make it a payable proposition. ELECTRIC SUPPLY. Mr. Summerson obtains his power from the Darlington Corporation, but a special transforming machine has been installed to transform the supply voltage down to the working voltage. Th? power supplied at Darlington is at 6000 volts pressure and 3-phase current about 40 amperes per phase. Single phase current for the furnace is obtained by means of this special machine designed by Professor Mi’cs-Walker, which is called a “phase balance.” By means of this the supply voltage is transformed down to 140 to 150 volts with a current of 2500 amperes. By a suitable arrangement of the coils the single phase current as used in the furnace is obtained without upsetting the balance of the phases in the 3-phase supply. This, of course, is necessary, in order to maintain a high power factor throughout the system. THE FURNACE. The furnace itself is cylindrical and about seven feet in diameter outside—what is known as the Luyder type. The interior is lined with magnesite bricks and firebricks, and the hearth is made of burned dolomite, mixed with pitch and tar and rammed, to the desired shape. The current is carried into the furnace by means of a 4-inch diameter graphite electrode. The ironsand is mixed with ordinary coke dust, along with limestone, and charged through one of the Side doors into the furnace. According to the firm’s analysis of the resultant metal, it is a grey iron suitable for foundry use, containing .20 per cent, titanium, 3.3 per cent, graphite, .2 per cent, combined carbon, 2.5 per cent, silicon, .5 per cent, manganese, .22 per cent, phosphorus, and sulphur nil. The yield of metal is over 50 per cent, .of the ironsand charged, the coke used 7cwt per ton of iron, and the lime 2cwt per ton of iron. DRAWBACKS OF BLAST FURNACES. Electric furnaces, therefore, are the solution of treatment of the ironsands. In the first place, because they get rid of the titanic acid, but there are apparently other economic reasons. It is calculated that there must be an output and an absorption of 200 tons of iron or steel per day before a blast furnace can be made to pay. Huge blast furnaces capable of such an output with all their accessories are not things to be installed for a few thousand ‘ pounds. They vary according to size from £lOO,-< 000 to £300,000, and a group such as one sees in the great smelting works of England would cost a million sterling to instal. It is too great a proposition for a young country, even though probably the Parapara ores could be treated in blast furnaces. All the economic factors in the steel smelting industry have to be so nicely balanced that there can be no waste in cooling furnaces and such things. Thus the market must, be large and consistent. THE ECONOMIC FACTOR. With the electric furnace it is possibb to compromise. A furnace capable of holding a few tons of metal is a matter of ten, twenty, or thirty thousand pounds, with its accessories. There is no waste of fuel. Ore may be converted when desired; and t?he process is riot dependent for the success on a very large output. Thus the industry might be begun in New Zealand by supplying the

local foundries with pig-iron, later with such quantities of steel as the machinery of the Dominion can treat. From this point one can imagine the growing possibilities, ending in flip expensive machnery for rolling and treating ®teel and, finally, an export trade. That, ’however, is a dream of the future. In the meantime, is it possible to produce pig-iron for the use of the foundries of New Zealand?