Service of refractories in reducing and iron-containing media

Abstract

One of the means of increasing blast furnace productivity and reducing the consumption of scarce coke is injection of reducing gases heated to high temperatures into the furnace.With injection of a reducing gas heated to 1200~ in a quantity of 950 m3/ton of iron into a 930 m 3 blast furnace at Tula Ferrous Metallurgy Production Union the coke consumption dropped by 95 kg/ton of iron [i].The use per ton of iron of 12-27 m 3 of natural gas heated to 700~ made it possible to increase blast furnace productivity by 1.7-2.9% and reduce specific coke consumption.Higher results are obtained with converter gas heated to II00-1200~ [2, 3].According to the data of [4] with injection into the blast furnace of 600 m 3 of reducing gas and 150 kg of heavy oil the coke consumption may be reduced to 250 kg/ton of iron and furnace productivity increased by 25%.In the experimental gas heaters of Tula Ferrous Metallurgy Scientific and Production Union the blast furnace gas, which has been cleansed by washing of carbon dioxide, is heated and then supplied to the blast furnace.After cleaning the gas contains 1.2-1.5% CO s , 57-80.6% CO, 3.2-8.7% H2, and 13-42% N 2. The moisture content of the cleansed gas is 15-40 g/m 3 (under normal conditions) and the content of dust from the blast furnace i-i0 mg/m 3. The chemical analysis of the dust is 12.1% SiO2, 42.5% Fe203tot, 5.8% FeO, 0.4% AI=O3, 0.1% MnO, 9.8% Femet, 0.11% P2Os, 11.0% CaO, 0.5% MgO, 0.3% S, and 11.0% C. The gas temperature at the entry to the gas heater is 20-40~ and at the exit I080-1250~The temperature of the dome is 1200-14000C.The checkerwork and the dome of the gas heaters are made of types MKV-72 (GOST 20901-75) and MLV-62 (GOST 13836-68) refractories produced by Semiluki Refractory Plant.After service for two years specimens for investigation were taken from the gas heaters. Under the action of the reducing gases and the iron-containing dust supplied together with the gas from the blast furnace significant shrinkage of the refractories, impregnation of them