Repairing a propane furnace

The furnace as described in this page has a burner entry which is exposed to very high temperatures. As a result, the refractory (rated to 1450°C) melts and softens and, moreover the steel burner nozzle melts. I repaired the burner entry by applying Blakite with my fingers (photo courtesy my girlfriend) which do the job better than any cement applying tool. As a tip from this forum the repaired burner entry acts as a burner flare made from refractory.

I fired this furnace to melt another sample of cast iron for 20 minutes which heated the cast iron to 1350°C. The inner part of the furnace was 1500°C. It withstood the heat well without cracking or softening.

Conclusion

Blakite is an excellent material not only to glue refractory bricks but also for plastering refractory bricks which are on the limit of its temperature rating.

Damage in the furnace chamber near the burner entry (below)	Burner head (20mm diameter) was molten which means that it is heated over 1500°C	Look into the burner entry from the outside. Note the damage on the right
Repairing the burner entry by applying Blakite with my fingers	Another picture of the repair with my fingers	Repairing inside the furnace chamber
The repaired furnace chamber as seen from top	The repaired burner entry	A large can of Blakite
The furnace interior after a firing to 1500°C. Burner entry is right. The white felt on top is ceramic fiber for sealing the lid.	Look into the burner entry after the firing	Graphiite crucible for cast iron used mor than ten times