Steelworks melt iron ore with coke and fluxes in a blast furnace to form molten iron.  Hot air is blasted into the bottom of the furnace from a ring of nozzles called tuyeres, pronounced “tweers”.   

You can make a small one in a paint drum.  

Wind a vacuum cleaner or pool cleaner hose around the inside bottom of the drum and lead it to the outside through a metal pipe.  Plaster the inside of the drum with about 50mm of Keratuff 2, covering the vacuum cleaner hose and the floor.  

Now, take a large diameter drill and drill holes through from the inside of the drum through the vacuum cleaner hose.  Now make a small fire in the drum, and when it is burning well, add some charcoal and connect a vacuum cleaner in blowing mode to the end of your pipe.  This will create an intense fire.  

Add a crucible with some metal into the combustion zone and it will melt quite rapidly.  Make sure you have a long handle or tongs for your crucible and ensure that it stays in the combustion zone.  

Have fun!