1964 Volume 50 Issue 13 Pages 2157-2166
In August, 1962, powder-coal injection tests were executed at the experimental blast furnace (about 05m3 inner volume 0.5m hearth diameter about 2m effective height) of the Institute of Industrial Science, Tokyo University. The furnace, ordinarily, was operated with 100% self-fluxing sinter (3-10mm size, CaO/SiO2=1.2) and consumed about 1.8t coke per day of 10-20mm size containing 88'1% fixed carbon and 10'9% ash. About 470kg coal per day of -1mm size, which contained 45% carbon, 39.5% volatile matter and 11.9% ash was injected through the 4 tuyeres by cold compressed air (about 0.45Nm3/min). For heat compensation, blast temperature was raised from 575°C (at normal operation period) to 670°C and oxygen was enriched so as to make its concentration in the blast about keeping total oxygen volume blown into the furnace per unit time the same as that at normal operation period.
Coke rate decreased from 1.478t/t (at normal operation) to 1.091t/t (by 26%), and pig output increased by 15%. Gasification ratio of coal was calculated to be only about 75%; nevertheless, apparent replacement ratio of unit coal was 1.13 unit of coke. This result is explained mainly by the remarkable decrease of solution loss caused by the reducing action of H2 contained in the coal: this enabled an increase of burden ratio, and therefore, that of pig output, which diminished relative heat losses due to top gas and radiation of furnace.
Coke equivalent of this heat economy, as well as that of carbon contained in the coal, was calculated, the sum of which was found to have nearly the same value as the obtained replacement ratio.