Darren,
As Andy says, you will end up with a real junky metal. Even the local scrap processor, who recycles ali, mainly for the automotive industry, has to be very careful what goes into the mix. Most of their labour force is into separating the different types of ali, and even then, they mix pure raw additives to it to get it something like.
I have worked with the raw material of a general mix as you are suggesting, and I will tell you now, it is not nice. Imagine trying to machine solidified evostik, it sticks to your cutter and sort of tears from the surface rather than cuts. I had a friend who used to work in a foundry casting steel mill rolls, and I asked him to melt some ali bits down and cast it into bars for me. I have tried all sorts of silly things in my time, that one turned out to be one of the silliest.
But to get back to your other thing about smelting. Melting the stuff.
When I do a steam rally in September, there is usually a chap next to me who casts and makes his own full scale engines, not large ones, say up to 18" tall. Resurrecting old industrial engines from the past, say for use in small farm dairies etc., of which there are no more examples, working mainly from original drawings and photos.
He does all his casting the old way, before furnaces etc. During the winter he does his melt on the open fire in the house, and in the summer he digs a pit in his garden for doing the same thing. He mentioned that once he has got things up to heat, things were no different to a normal furnace, he would just keep adding his ali scrap, and taking out what he needed for the pour. He told me his most prized possession was a large stainless steel vessel that he uses for his smelting. I think it must be something like the deep pans they use in a canteen servery.
He was also saying that he uses the old techniques for casting, no specialised oiled sand etc, he uses very finely riddled dry earth. It seems to work, as his engines look very nice and always attract a good following.
John