本溪湖に於ける低燐銑(純銑鐵)の製造に就て

Abstract

The Miao-erh-kou iron mine is situated at about 20 miles north east of Pen-hsi-hu on the Anfeng line (between Antung and Mukden) of the South Manchuria Railway. The ore deposit is of magnetite in bedded intercalated in schistose plane of granitic gneiss and mica-schist of Pre-Cambrian age. The present annual output of the rich ore (65% Fe) reaches to about 240, 000tons.The ore concentrating plant is in the vicinity of the Nanfen station, about 5 miles apart from the mine, and there magnetic concentration of the rich ore or dephosphorization is operated by the Gröndall process. The annual capacity of the plant can be reached to 110, 000tons after its recent extension.The concentrated ore is transported to Pen-hsi-hu by railway and there briquetted by the, press machine and desulphurized and oxidized into hematite composition passing through the Sutcliffes tunnel kiln which is heated by coke oven or producer gases. There are two kilns, each capacity being about 40, 000tons per year. The briquettes are porous, reducible, and very pure as shown in following analysis:Fe 69% SiO2 1% P 0·007% S 0·009% Porosity 25%The coal field at Pen-hsi-hu consists of carboniferous coal measures with 8 seams of semi-anthracite. It has strong caking power, and is suitable to use for making coke. Above all, coal in the Poza seam which is the uppermost one is very low in phosphorus and sulphur, so we can make low phosphorus coke from it through the Kuroda's byproduct coke ovens after careful washing. The standard analysis of low phosphorus coke is as follows:-F.C. 83% Ash. 14% P 0·01% S 0·45%Besides these two chief raw materials, we purchase some manganese ores which are low in phosphorus. Limestone as flux, forms the base of the Pen-hsi-hu coal mine, and quarzite-pebbles are also found at the riverside near the works. In every one charge, a small quantity of quarzite is mixed for two purposes, one is for supplementing necessary Si in pig iron produced from briquettes which contain insufficient SiO2, and the other is for the safety of desulphurization in pig iron keeping the moderate slag quantity with limestone in quite basic compositions.At the Pen-hsi-hu Iron Works, there are two blast furnaces, with daily capacity of 200tons each, and various foundry, basic, and low phosphorus pigs ammounting to 150, 000tons per year are produced, of which about 50, 000tons being low phosphorus this year (1934). To make low phosphorus, the above mentioned raw materials are used in proper mixture in charge, and we succeeded in it by carefully controlling the furnace running with a small quantity (30-35% per ton pig) of moderate basic slag, and using quite high temperature blast. We are able to produce very pure iron which is low in P, S, Cu, and Si as same as Swedish charcoal pig, and also low in P and S, but high in Si and Mn such as hematite pig according to demands. The analysis of the Ist class which is main product, is as follow:-P 0·025% below S 0·015% below Cu 0·015% below Mn 0·50% above Si 1·0% aboveAll the low phosphorus products are exported to Japan and mainly used in acid open heartbs.The demand in Japan has increased rapidly since two or three years ago, especially in this year its demand has reached to about 50, 000tons. The importation of low phosphorus pigs to Japan hither to made from Sweden and England is almost excluded at present.In near future, we shall be able to produce 75, 000tons a year by further enlarging the briquetting plant.