First Melt

The time has finally come to see if my furnace will melt anything. Gingery's book calls for a double layer of charcoal on the bottom to get started and add to it as needed to maintain heat. I will start with that but I am doubtful that I will get enough heat going to melt anything with just a double layer on the bottom. I built my furnace twice as large as the furnace described in Gingery's book so my guess is that it will take quite a bit more than that. Keeping that in mind I have also decided to try melting some aluminum scrap first beacause of the lower temperature requirements to melt aluminum.

Here is the furnace layout all ready to get started.

To get the furnace ready I added a triple layer of charcoal on the bottom of the furnace and let them burn until they had all turned white. Just as you would to get a grill ready to cook on. Once those were going I set the crucible on top of the coals and added some additional charcoal along the sides of the crucible. Then I added several crushed aluminum cans to the crucible, turned on my shop vac, adjusted the flow down low and put the lid on the furnace That is when the waiting game started. After 20 minutes I noticed that the bottom of the crucible was glowing a dull red but after poking around on top of the cans it didn't appear that they were beginning to melt.It also appeared that most of the charcoal on the bottom had been used up so I lifted the crucible out of the furnace and added more charcoal and put the crucible back in place. I put the lid back and placed a small brick made out of leftover refractory mix on top of the vent hole. I didn't completely cover the vent, maybe about 90%. After it appeared that the new coals were going I increased the air flow a little bit in an attempt to bump the temperature up inside the furnace. That seemed to work and I finally noticed the aluminum starting to melt in the crucible, which was surprisingly exciting to see. It may have taken about 30 minutes longer than I had expected but it was working! Once the melting got started it seemed to melt all of the cans that I had placed into the crucible quite quickly so I removed the lid, skimmed off the slag, added more cans and closed the furnace up again. Once again the cans melted quite quickly and I also discovered something new. Aluminum cans leave have a LOT of impurities to remove as they melt. I was unsure of how much slag to expect and what it would look like etc. but once I saw it, it was obvious. So after reloading the crucible three times and skimming the slag I stirred the aluminum up to try to get a feel for it's consistency.

Here is a little tool that I made to skim slag from the melt. I also used it to stir the melt. It worked but I do think that I will buy a carbon rod to use for stirring.

Ultimately I finished up the night getting three melts in. I had stolen on of my wife's muffin pans to make ingots which seemed to work quite well for aluminum and I think the ingots gave me a good head start on removing the impurities of the cans. I hope that the  various other non-can scrap that I have will not create so much slag.

The first batch of ingots! Not a lot but I kept the first load small.