Blow mold

Nozzle and/or tuyère (see hot blast nozzle) at cupolas and blast furnaces for feeding cold and hot air into the furnace shaft.

These nozzles are cooled by water and extend into the furnace with a slight inclination of 3 to 10 degrees. They are made of special wrought copper and the integrated cooling system is made for high pressures which can occur in case of disturbances. The nozzles are installed in cooling rings of melting plants in a way that they can be easily exchanged in case of damage (Fig. 1). For ensuring a consistent wind distribution, the number of hot blast nozzles in adapted to the furnace diameter.

The furnace diameter is designed according to the required throughput and/or the required blast rate. The following reference values apply:

 5 – 10 t/h4 nozzles
10 – 15 t/h5 nozzles
15 – 30 t/h6 nozzles
30 t/h8 nozzles

The nozzle cross-section has to be adapted to the required wind speed relating to the furnace diameter. This ensures a penetration to the middle of the furnace and prevents a wall effect. At the same time, the burning zone is pulled inward, away from the furnace wall.


  • Fig. 1: Quick-change copper nozzle including cooling ring and easily soluble nozzle fitting (according to F. Neumann)
  • Fig. 2:  Blast furnace blow mold (Source: voestalpine AG, Linz, Austria)