Some refractory mix’s will not stick to metal but furnace cement sticks nicely to metal and my guess is that the refractory will bond some to the furnace cement. So I first apply furnace cement to the bottom of the tank then sand it a bit to roughen the surface some. Before that I use heat to help remove some of the surface oil on the bottom of the tank plus sand paper and a solvent like Colmen cook stove fuel. Most of my tanks had some kind of oil in them. I also drill four holes in the tank and install four bolts that stand up inside the tank. This gives something for the refractory to hold on to. The last step is to cast the refractory.
Inside.
That’s the only photos that I have.
Next I’ll dig up what refractory I used.