After successfully completing its 18,016th heat of steel production, the No. 2 converter at the steel plant was shut down smoothly, marking the successful completion of its current service life. This figure not only signifies that the No. 2 converter has set a new historical record for service life, but also surpasses the previous record of 4,952 heats.
Maintaining the converter lining is crucial for ensuring its service life. Steel plants, by understanding the erosion patterns of the lining, develop repair cycles and maintenance plans, and rationally optimize the frequency and timing of various maintenance measures such as hot repair, spray repair, and slag splashing. Adhering to the principle of “prevention first, precise maintenance,” a solid foundation has been laid for the long-term stable operation of the converter.
The furnace fire is temporarily extinguished to allow for an even more intense combustion. Furnace 18016 is an end point, but also a new beginning. Currently, converter No. 2 has entered the planned maintenance phase. Maintenance personnel will conduct a comprehensive overhaul of this “meritorious furnace,” accumulating strength for the next stage of the journey.
How to increase the lifespan of a converter
Extending the lifespan of a converter is a systematic project involving multiple aspects such as furnace lining materials, smelting processes, operation control, and equipment maintenance. Below are some common methods for extending the lifespan of a converter:
Optimize furnace lining materials
- Choose high-performance refractory bricks: Use refractory materials with good erosion resistance and thermal shock resistance, such as magnesia-carbon bricks and magnesia-chrome bricks, and rationally match refractory bricks of different materials and thicknesses according to the erosion characteristics of different parts of the furnace lining.
- Improve the masonry process: ensure the quality of refractory brick masonry, guarantee tight and uniform brick joints, and reduce furnace lining damage caused by masonry defects.
Precise control of slag composition
- Adjusting the MgO content: Controlling the MgO content in the final slag to 9%-12% forms a high-melting-point magnesium slag layer, improving the refractoriness and erosion resistance of the splashed slag layer.
- Controlling FeO content: The FeO content in the final slag is generally controlled at 14%-16%. Too high a content will exacerbate the chemical erosion of the furnace lining, while too low a content will affect the bonding strength between the slag splash layer and the furnace lining.
- Stabilize alkalinity: Control the slag alkalinity (CaO/SiO₂) between 2.8 and 3.2 to balance the effects of dephosphorization and desulfurization with the requirements of furnace lining protection.
Enhanced slag splashing furnace protection technology
- Optimize slag splashing parameters: Reasonably control the slag splashing gun position, nitrogen pressure, flow rate and slag splashing time to ensure that the slag splashing layer uniformly covers the furnace lining with a thickness of 30-50mm.
- Improve slag conditioning process: Add slag conditioner in a timely manner during or after tapping to adjust the slag composition and fluidity, and improve the slag splashing effect.
- Strengthen the slag consolidation process after slag splashing: promote the sintering of the slag layer and improve its strength and stability by means of nitrogen blowing for cooling and furnace shaking to replace the furnace gas.
Optimize smelting process
- Controlling tapping temperature: For every 1°C reduction in tapping temperature, the furnace life can be increased by approximately 100 heats. Keeping the tapping temperature below 1620°C reduces the erosion of the furnace lining by high temperatures.
- Shorten the blowing time: Optimize the oxygen supply system and slag-making process to improve smelting efficiency and reduce the exposure time of the furnace lining at high temperatures.
- Reduce the number of back-blowing cycles: improve the endpoint hit rate and avoid increased slag oxidation and furnace lining erosion caused by back-blowing.
Standard operating procedures
- Stable charging system: control the charging amount and avoid overloading; adopt a reasonable material distribution method, such as “large pieces in the center and small pieces around the perimeter”, to reduce the mechanical impact of scrap steel on the furnace lining.
- Properly control the lance position: Adjust the oxygen lance position according to the smelting stage and slag condition to avoid uneven furnace lining erosion or slag splashing caused by the lance position being too high or too low.
- Strengthen production organization: Rationally arrange production rhythm, reduce the interval time of converter, and reduce the impact of thermal stress on furnace lining.
Strengthen equipment maintenance
- Regularly inspect furnace lining thickness: Use laser thickness gauges, infrared imaging and other technologies to monitor furnace lining wear in real time and promptly identify weak points in the furnace lining.
- Timely repair spraying: For locally eroded areas of the furnace lining, use methods such as thermal spraying and flame spraying to repair them and restore the integrity and strength of the furnace lining.
- Maintenance of the tapping spout and trunnion: Regularly inspect and replace the tapping spout to maintain its shape and size; perform heat insulation and cooling treatment on the trunnion area to reduce thermal stress concentration.
By implementing the above comprehensive measures, the lifespan of the converter can be effectively increased, refractory material consumption reduced, and production efficiency and economic benefits improved. Specific operations need to be adjusted and optimized based on the converter’s equipment conditions, raw material characteristics, and production requirements.
