It _will_ anneal _all_ aluminum alloys, affect many steels, and melt many zinc alloys. You have to be careful what you put in.
You also have to sandblast afterwards to remove the ash. That puts back some of the labor content you didn't need for the burning, and greatly increases the volume and weight of the toxic waste stream you must pay to get rid of.
It probably makes sense in California.
Mike Halloran
Pembroke Pines, FL, USA