Abstract: Fly ash is agglomerated into pellets in order to render it environmentally harmless and suitable for dumping. The fly ash is mixed with water in an unclassified condition and formed into green pellets which are heated in a two-stage heating process. In the first heating stage carbon in the pellets is rapidly gasified while iron present is not reduced below Fe.sub.3 O.sub.4. In the second heating stage, the pellets are rapidly sintered. The whole heating process is less than 60 minutes and to permit this rapid heating, the pellets must be of sufficient porosity to withstand the rapid gasification of the carbon and the rapid sintering without breaking up.