giantdude33 Posted July 3, 2023 Share Posted July 3, 2023 I need to remove the refractory from a cast forge pan in order to free up and remove the firebox. I don't want to use Muriatic acid to "eat" the concrete if I can avoid it. I have tried a chisel to break it but it is strong stuff and I am concerned about breaking the cast pan. Any knowledge/wisdom/advise from everyone with more experience and smarter than myself would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
JHCC Posted July 3, 2023 Share Posted July 3, 2023 One word: patience. It may very well be that the only thing that will work is a hammer and chisel. Go slowly, wear PPE, and don't try to do too much too fast. If you find yourself getting impatient, take a break: it's almost always that frustrated hard blow that does the damage you're trying to avoid. Quote Link to comment Share on other sites More sharing options...
Les L Posted July 3, 2023 Share Posted July 3, 2023 drilling several holes in the refractory, with a masonry bit, may help to break it loose Quote Link to comment Share on other sites More sharing options...
Scott NC Posted July 3, 2023 Share Posted July 3, 2023 I was going to suggest carefully scoring it with a grinder disc and breaking it out in chunks, but have never tried something like that. Safety First! Quote Link to comment Share on other sites More sharing options...
NoGoodWithUsernames Posted July 3, 2023 Share Posted July 3, 2023 I think if you can find a masonry disc for an angle grinder and score it like Scott recommended might work well. Maybe combined with the masonry drill bit you could remove just the refractory around the fire pot and not have to re-cast the entire thing when you're finished. Quote Link to comment Share on other sites More sharing options...
JHCC Posted July 3, 2023 Share Posted July 3, 2023 A masonry disk in an angle grinder is a very good idea. PPE is a MUST!! Question: are you sure that this is refractory cement, or is it regular concrete? Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 3, 2023 Share Posted July 3, 2023 Phosphoric acid will dissolve it whatever it is without damaging the cast iron. Just be Very VERY careful, too much can react energetically on contact with portland cement concrete! Test with one or two drops and observe the reaction. Don't make me tell you to wear PPE suitable to handling a STRONG acid! Scoring it is an excellent idea but it may be too well bonded to the pan to come out in chunks. However, chiseling towards holes is an easier way to break out stubborn masonry. Drill a hole, say 1/2" dia. Place mason's chisel about 1/2" from the edge and angle it intersect with the bottom edge of the hole and smack it. You should be able to do the same thing after cutting deep notches with a masonry disk and break it towards the cuts. Saving the cast iron pan is important so take a look at the underside periodically, especially if you knock out a large chunk. Hmmm Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
giantdude33 Posted July 4, 2023 Author Share Posted July 4, 2023 Thanks for all of the great suggestions. After I posted I was able to break out a small chunk. Then, with the patience everyone suggested, I was able to chip out larger chunks separating them from the cast pan. It took a couple of hours but it is completed without any casualty ( to the forge of course). Thanks again for everyone's assistance!! Quote Link to comment Share on other sites More sharing options...
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