Abstract: A furnace includes: a furnace body; a housing rotary body including a plurality of side walls, a plurality of housing chambers partitioned by the side walls and disposed circumferentially in multiple stages, each including multiple housing chambers, and a space disposed in the central portion of the housing rotary body to provide a donut shape in plan view; a rotary driving device for rotating the housing rotary body; a heating device for heating the air inside the furnace body; a first and a second partition wall which together partition the inside of the furnace body into the first and the second zone; a first flow passage communicating a blowout port of the fan with outer circumference sides of the housing chambers in the first zone; and a second flow passage communicating outer circumference sides of the housing chambers in the second zone with a suction port of the fan.

Abstract: A vortex chamber includes an outer circumference wall, a container, an annular shoal portion provided between the container and the outer circumference wall so as to encircle the outer circumference of the container, and a dam portion protruding upward from the upper surface of the outer circumference of the container so as to partition the container from the shoal portion. An undried nonferrous metal block is fed into the shoal portion, the block having such a size that is not completely submerged into the molten metal in the shoal portion. The fed nonferrous metal block is gradually melted to have a reduced volume of small pieces and particles of nonferrous metal, which are re-circulated in the shoal portion, flown over the dam portion, and dropped into the container, thereby forming a vortex in the container in which remaining small pieces and particles submerged into the molten metal are melted.

Abstract: A combustion apparatus comprises a pair or more than two pairs of burner groups. Each burner group comprises one regenerator per a plurality of burners. In each pair of burner groups, a first burner group and a second burner group are fired alternately and waste heat produced when the first burner group is fired is stored in a regenerator of the second burner group. The stored waste heat is utilized to preheat the combustion air of the second burner group when the second burner group is fired. Similarly, waste heat produced when the second burner group is fired is stored in a regenerator of the first burner group, and the stored waste heat is utilized to preheat the combustion air of the first burner group when the first burner group is fired.