Aluminium
White dross from primary aluminum production and from secondary recycling processes still contains useful amounts of aluminum that can be extracted industrially. The process produces aluminum billets, together with a very complex waste. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, hydrogen, acetylene, and ammonia), which ignites on contact with air. Even with these difficulties, the waste is used as a filler in asphalt and concrete.