PyroGenesis Canada Inc. announced that it has filed for patent protection for its energy efficient, salt-free recovery of metal from zinc and aluminum dross. Dross is a residue from metallurgical processes that is generated when hot molten metal contacts air. Current practices often require zinc and aluminum smelters to ship their dross residue to a third party for expensive treatment and metal recovery. PyroGenesis' technology, DROSRITE Plus, treats hot dross right at the smelter, resulting in improved metal recovery and a significant reduction in greenhouse gas generation.