Abstract: A method and apparatus for economically melting matrix materials, said apparatus comprising a drier, a vertical furnace including a unique arrangement of refractory bars and a rotary kiln and the method including passing the solid matrix material first through a dryer which is heated by the waste gas of a vertical furnace, then to the top of the vertical furnace where it is melted by direct flame contact and thereafter cascading the melted material downwardly through said arrangement of refractory bars as the exhaust from a rotary kiln is blown upwardly through the vertical furnace with the melted material finally flowing from the bottom of the furnace into a rotary kiln where it is further heated and mixed prior to discharge.