One method of treating incinerated waste comprises: size separating at least some of the incinerated waste into a first undersize fraction comprising particles smaller than the first separation size and into a first oversize fraction comprising particles larger than the first separation size; size reducing at least some of the first oversize fraction; size separating at least some of the size-reduced first oversize fraction into a second undersize fraction comprising particles smaller than the second separation size and into a second oversize fraction comprising particles larger than the second separation size; combining at least some of the first undersize fraction and at least some of the second undersize fraction into a fine fraction; and extracting metal from at least some of the fine fraction. Another method of treating incinerated waste comprises extracting metal by froth flotation from at least some of the incinerated waste. Systems are also disclosed.

A method for removing elements, including heavy metals, from fly ash and from fly ash resulting from removal of SO.sub.x/NO.sub.x from flue gas using Na.sub.2CO.sub.3/NaHCO.sub.3/trona, is described. An aqueous suspension of the fly ash and/or a solution of the leachate from the fly ash is treated with dissolved ferrous compounds, such as FeSO.sub.4.7H.sub.2O and/or FeCl.sub.2.4H.sub.2O, at a chosen initial acidic pH, and the precipitation of the ferrous ions as the solution basifies sequesters the trace elements.

There is provided a method for separating an input feedstock using thermal plasma to obtain a processed feedstock and/or remove one or more hazardous compounds. There is also provided system for same comprising a plasma vortex reactor and a separator. There is also provided a method for forming a product from an input or processed feedstock using thermal plasma. There is also provided a system for same comprising a blender and a plasma rotary furnace.