Rotary hearth furnace with lightened construction

A rotary hearth furnace for treatment of minerals, including a toroidal chamber wherein a bottom wall comprises a hearth which rotates relative to the chamber, said hearth including a refractory material layer supported on a frame which includes tracks cooperating with wheels, placed on the ground, for the sliding or driving of said hearth, said frame including several girts arranged radially as to said hearth and angularly equidistant from each other, and at least two circular sliding girders positioned next to outer and inner peripheral edges of said hearth, said sliding girders in contact with the hearth wheels through the tracks, the sliding girder positioned next to the outer peripheral edge of the hearth having an inertia moment greater than that of the sliding girder provided next to the inner peripheral edge, each sliding girder being tubular with a rectangular cross section and all girders comprising the same material, the walls of the sliding girders positioned next to the outer peripheral edge of the hearth having a thickness substantially double the thickness of the sliding girders provided next to the inner peripheral edge, said sliding guides having a mechanical strength substantially proportional to the length of their circumference, and said wheels being angularly equidistant from each other with the same angular pitch as that of said radial girts.