EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

Intensive operation of blast furnace allows an increase in production of hot metal and profitability of Iron & Steel Works. However, blast furnace structural integrity could be sacrificed if no measures are taken to protect refractory lining and to build stable accretion. NTMK-EVRAZ is a unique and advanced blast furnace operation with titania load of about 45-50 kg TiO2/thm. Successful operation of NTMK’s blast furnaces is guaranteed by deviation of blast furnace process from thermo-dynamical equilibrium to suppress formation of titania carbides and nitrides. As a result ultra low silicon and titanium hot metal is produced. The paradox is that despite of high titania load there is no any better protection to the hearth refractories as compared to conventional blast furnace and addition of titania or shungite does bring any benefits. NTMK and Hatch developed a systematic approach to monitor conditions of BF hearth lining using Acousto Ultrasonic-Echo (AU-E) non-destructive testing developed by Hatch. Continuous and periodic inspection of blast furnaces revealed problematic areas with accelerated refractory deterioration and minimal thickness, formation of elephant foot, extent and speed of refractory wear, cracks and other anomalies. Improvement in coke quality, staves washing, control of ore load distribution, periodical slow run of the furnace etc. were recommended and implemented to prolong furnace life and predict the end of campaign while maintaining the intensity of furnace operation.