An environmentally sound process is described for the remediation of waste materials that allows the separation, recovery and decontamination of metals. The method includes chemically reducing essentially all of a reducible toxic and potentially hazardous metal-containing component of a waste composition. The waste is directed into a molten metal bath, including a first reducing agent which, under the operating conditions of the molten metal bath, chemically reduces a metal of the metal-containing component to form a dissolved intermediate. A second reducing agent is directed into the molten metal bath. The second reducing agent, under the operations of the molten metal bath, chemically reduces the metal of the dissolved intermediate. The rate at which the second reducing agent is directed into the molten metal bath, relative to the rate at which the component of the waste is directed into the molten metal bath, is sufficient to cause essentially all metal-containing intermediate formed to dissolve in the molten metal bath, thereby indirectly chemically reducing the component of the waste. This indirect reduction technology can remediate a variety of materials, including ash metal-contaminated municipal waste, vitreous slag-like materials and spent metal catalysts, while allowing the recovery of remediable metals.