Assessment of the effectiveness of technological measures to extend the campaign of blast furnace No. 5 of PJSC Severstal (2006 – 2024) based on an examination of its working space during a first-category overhaul

The paper presents the findings from the study of the working space of blast furnace No. 5 of PJSC Severstal during its first-category overhaul in 2024 lasting 17.46 years, which significantly exceeded the standard service life. The effectiveness of technological measures taken to extend the furnace’s campaign from 2006 to 2024, aimed at protecting the refractory lining in critical areas such as the hearth, lower shaft, and the upper bosh, was evaluated. The residual thickness of the refractory lining in the shaft, hearth, and metal receiver is analyzed, and maps showing the actual thickness of the lining across different sections are generated. The measured maximum wear of the shaft refractory lining is 344 mm (37.4 % of the original value); the measured maximum wear of carbon blocks in the area of cesspool openings – 313 mm (23.4 % of the original block size). In the upper part of the hearth, the minimum residual thickness of refractories with an Al 2 O 3 content of 43 % is 220 mm or 31.9 % of the initial value. The paper also discusses safe remote measurement methods, including 3D laser scanning of the furnace shaft during the removal of residual charge materials. It highlights the advantages of ground-based laser scanners in capturing dense, high-quality 3D geometric data. Additionally, the paper describes the experience of remotely measuring the residual thickness of carbon blocks around the raking openings. Comparisons are made between the actual residual thickness of the refractory lining in the hearth, bottom carbon blocks, and high-alumina refractories of the tuyere zone, and the results obtained using ultrasonic echo-sounding technology (AU-E) during the furnace’s operation. The paper also includes a description of the stress wave propagation technology, which utilizes data analysis in the time and frequency domains to determine lining thickness and detect anomalies. The results of the current and previous blast furnace campaigns are compared in terms of pig iron production, the number of cooling system failures, and refractory wear across the entire working space of the furnace. The total production of pig iron in the 2006 – 2024 campaign, related to the furnace area, amounted to 420.0 thousand tons/m 2 and exceeded the figure for the previous campaign by 1.90 times.