IRON REPORT ON THE ELECTRIC SMELTING AND REFINING OF), AND THE PRODUCTION OF BASIC SLAG.

Appendix to the Journals of the House of Representatives, 1916 Session I, C-14

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1916 NEW ZEALAND.

IRON REPORT ON THE ELECTRIC SMELTING AND REFINING OF), AND THE PRODUCTION OF BASIC SLAG.

Laid on the Table of the House of Representatives by Leave.

Report by E. Parry, B.Sc, M.1.8.E., etc., Chief Electrical Engineer. Electric Smelting and Refining of Iron. Public Works Department, Wellington, N.Z., 3rd August, 1916. Memorandum for Under-Secretary. In reply to your inquiry dated 2nd August, regarding cost of electric smelting and refining of iron, I have all the information necessary to give a detailed report on this subject, but in order to answer the question satisfactorily it will be necessary to localize the works and form an estimate of the market. Without going into detail, however, I may state that the cost of electric smelting of ironores in Sweden is less than the cost of the blast-furnace process, but the Swedes have a particularly pure ore to deal with, and moreover charcoal is used instead of coke for reducing purposes, whilst the filrnaces are much smaller in size than the blast furnaces in England and America. The consequence, therefore, is that where water-power is cheap, and where a special grade of iron is produced from pure ores with the use of charcoal, electric smelting is cheaper than the blastfurnace smelting. This is particularly the case if steelmaking and refining of the iron is carried on >y*nultaneously with the smelting operations, so that the waste gases resulting from the smelting of the ore can be utilized for converting into steel and for refining. On the contrary, where lower grades of ore only are obtainable (and this applies to the vast bulk of ore in the world), and where coal is cheap, and where the demand is such that pig iron can be produced on a large scale at the rate of 700 to 2,000 tons per week per furnace, electricity has not a hope of competing with the blast furnace under these conditions —that is to say, where pig iron has to be produced of ordinary everyday quality from average quality of ore, a blast furnace is unrivalled. Next, as regards the use of electricity for remelting and refining of iron, electricity is coming into general use at a very rapid rate for this purpose. It will not, however, supersede the Bessemer process or the open-hearth process for ordinary classes of steel in bulk, but is being used, and will in the future be used, to a large extent as an ancillary to these processes for refining purposes and for preparing the higher quality of steel. It is also being used at a rapidly increasing rate for foundry purposes, and is specially adapted for this class of work, as it will deal with a greater variety of material than the ordinary converter in use in foundries and engineering-works is capable of doing. Another use to which electric furnaces are being put very largely is for reheating and annealing purposes, and it has a special field all its own in the production of special alloys of iron which cannot be produced in any other way, or if produced cannot be done so economically. As regards New Zealand, the two principal sources of iron are the Parapara iron and the Taranaki ironsands. The Parapara iron-ore is of medium quality as regards the iron-contents, and can probably be more economically produced and smelted by the blast-furnace process as long as coke is available in New Zealand. As regards the Taranaki ironsands, I believe that there exists here a source of considerable industry which will be developed in course of time for making a special quality of pig iron in which titanium will play an important part, and also for the purpose of making alloys of iron and titanium for special purposes, and, given a demand for specialquality pig iron and ferro-titanium alloys, these could be more economically produced from the ironsands by means of an electric furnace than by the blast-furnace process. The reason of this is that the fine grains are not suitable for use in a blast furnace, because they tend to choke the furnace, and also are liable to be carried away by the blast. Consequently some form of

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briquetting has to be adopted, which adds to the expense, and moreover does not enable the blast furnace to work at its best advantage, so that both the size and the nature of the ore in this case are not suited for blast-furnace reduction, whilst, on the other hand, its quality is such as to command a higher price, which will justify the electric process. I confidently anticipate important developments in the utilization of the Taranaki ironsands as soon as electricity from water-power is available, but I do not think much will be done in the absence of these facilities. We have an example in several different directions of the result of providing electricity in Christchurch and neighbourhood, and, to mention only one result, I anticipate that before very long electric steel furnaces for foundry purposes will be in use in Christchurch. Manufacturers are satisfied as regards the price, and are simply awaiting an investigation which I have undertaken into the adaptability of the electric furnace for dealing with the various types of material available for foundry purposes. As soon as we are definitely assured which, type is best suited for New Zealand conditions, two or three electric furnaces will be procured forthwith. This is only one instance of the result of providing facilities in the way of electric power, and the extension of these facilities throughout New Zealand would practically revolutionize production. As regards the production of basic slag, this is a by-product of the basic process when creating highly phosphatic ores, which are to be avoided in steel-manufacture if possible—that is to say, no one cares to treat an ore high in phosphorus if he can obtain purer ores; but if, as is the case in Germany, a producer has no other ore available and wishes to develop his local sources at an additional cost to the country generally, such ores can be reduced, provided that the phosphorus is in excess and the pig iron converted to steel by the basic-lined converter or the basic open-hearth process as distinct from the acid Bessemer process or the acid open-hearth process. It should be understood that ores containing a medium proportion of phosphorus are not marketable at the present day: either the phosphorus has to be so very small in amount — i.e., less than o'os per cent. —or must be fairly high—in the neighbourhood of about 3 per cent. —when it lends itself to the basic process. B. Pabry, Chief Electrical Engineer.

Approximate Cost of Paper. —Preparation, not given; printing (750 copies), £1 2s. 6d.

Authority : Marcus F. Marks, Government Printer, Wellington. 1916

Price 3d.]