According to Japanese research on the wear of blast furnace main trough linings, the lining near the taphole suffers severe erosion due to direct molten iron冲刷, with an erosion rate typically ranging from (6.0–8.5) × 10⁻⁶ mm/s. This rate is proportional to the 1.9th power of molten iron flow and the 2nd power of slag volume. In the rear section of the trough, where the iron flow velocity decreases, the wear rate slows down to
In recent years, companies such as Nippon Steel, Krosaki Harima, and Shinagawa Refractories have developed three advanced construction methods—N-Cast (pouring method), VE (vibration molding method), and SVP (dry vibration molding method)—to replace traditional ramming techniques. These methods extend lining service life, improve construction efficiency, and reduce refractory consumption. Their key advantage is that they reuse the remaining lining without removal, minimizing material waste.
- N-Cast Method: Uses a vibrator inserted directly into the wet refractory mix (higher moisture content).
- VE Method: Employs a core-mounted vibrator, utilizing the thixotropic properties of low-moisture mixes—material flows under vibration and solidifies afterward.
- SVP Method: Similar to VE but uses no water, allowing immediate use after molding. The main difference lies in the core mold structure and moisture content (VE: 4–6% water; SVP: water-free).
Figure 9-32 illustrates the N-Cast and SVP methods. The construction steps for these techniques are:
- Remove residual iron/slag and clean the trough.
- Set up the mold with added weight or install a vibration molding machine.
- Add refractory material and compact via vibration.
- For castable refractories, curing takes 1–2 hours, followed by 7–8 hours of drying.
- For vibration-molded refractories, only 0.5 hours is needed post-molding, but dust control (via trace liquid oil additives) is required.
Compared to traditional ramming, these methods:
✔ Reduce construction time to 1/10
✔ Cut labor by 80%
✔ Double service life
✔ Lower refractory consumption by 33%
