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Transactions 



To make pig of this low value economically cheap production is essential ; 

 hence large furnaces, hot blast, labour-saving appliances, and an output 

 of at least 1,000 tons a week are required. The cheapest flux for the silica 

 in the ore is limestone, of which (assuming slags running 40 per cent, silica, 

 16 per cent, alumina, and 39 per cent, lime for the white iron, and 35 per 

 cent, silica, 14 per cent, alumina, and 46 per cent, lime for the grey) 12 cwt. 

 would be required per ton of v/hite iron and 15 cwt. per ton of grey iron. 

 Such limestone must be over 95 par cent, calcium carbonate, and should 

 not contain over 1 per cent, of magnesia. The presence of such pure 

 limestone in accessible position and sufficient in quantity for an output 

 of 40,000 tons per year is problematical, but geologists generally are 

 reassuring on this point ; frequently, however, speaking with an im- 

 perfect appreciation of the metallurgical requirements, as in Bulletin No. 3. 



The only suitable fuel available at present in large quantities is the 

 hard dense Westport coke, which would probably run from 0-7 per cent, 

 to 1-2 per cent, sulphur. One ton would be required for making white 

 iron, and 25 cwt. for grey, per ton of iron. Also per ton of iron 4-6 tons 

 of highly preheated air would be required. The capital cost can now 

 be assessed. Two furnaces (one stand-by) would be required, 80 ft. high, 

 20 ft. in diameter, and 20,000 cubic feet capacity. This would give 

 1,000 tons of pig iron per week from 2,200 tons of ore, 1,000-1,250 tons 

 of coke, 400-600 tons of limestone, and 5,000 tons of air, and would cost 

 £50,000 in England and about £90,000 in New Zealand. Estimating the 

 cost of mining the ore at 4s. 6d., of calcining it at Is. 3d., of limestone at 

 7s. 6d.. and of coke at £1 15s. (all per ton), we would have — 



Table I. — Parapara Pig. 



The exportation of pig is clearly out of the question, and sole dependence 

 must be placed on the New Zealand market, which would at present absorb 

 about 4,000 tons per annum of grey foundry pig of Parapara quality, leaving 

 46,000 tons of white pig for steel-making. This pig is too impure to produce 

 higher-quality steels for the foreign market, and there is little demand for 

 huch in New Zealand ; hence the only outlook is for cheap steel for the 

 bar and rod trade. This can only be made from Parapara pig by the basic 

 open-hearth process, where we are at once confronted with the sulphur 

 difficulty, both in the pig and in the coal for use in the gas-producers. 

 The coal now mined in the Liverpool seam of the State mine runs under 

 1 per cent, sulphur, but is probably too caking in its nature for easy and 

 cheap treatment in a gas-producer ; however, it could certainly be used 

 for this purpose, but would cost over £1 a ton. 



