Furnace for defluorinating phosphate rock

Claim 1

IN A FURNACE FOR THE PRODUCTION OF MOLTEN DEFLUORINATED PHOSPHATE ROCK HAVING A HEARTH SECTION SURMOUNTED BY A SHAFT SECTION, MEANS FOR CHARGING PHOSPHATE ROCK LOCATED AT THE TOP OF THE SHAFT SECTION, AT LEAST ONE FLUID FUEL BURNER IN THE HEARTH SECTION AND A TAPHOLE AT THE BOTTOM OF THE HEARTH SECTION, THAT IMPROVEMENT WHICH COMPRISES A SUBSTANTIALLY ROUND VERTICAL-WALLED HEARTH SECTION CONSTRUCTED OF A SINGLE LAYER OF GRAPHITE BLOCKS; A VERTICAL-WALLED SHAFT SECTION SURMOUNTING SAID HEARTH SECTION AND HAVING AN INTERNAL DIAMETER SUBSTANTIALLY THE SAME AS THAT OF THE HEARTH SECTION; SUPPORTING MEMBERS INDEPENDENT OF THE HEARTH SECTION, DISPOSED TO BEAR SUBSTANTIALLY THE ENTIRE WEIGTH OF THE SHAFT SECTION; MEANS FOR EXERTING UNIFORM PRESSURE UPON A SMALL PART OF EACH GRAPHITE BLOCK OF THE HEARTH SECTION TOWARDS THE VERTICAL AXIS OF THE FURNACE DISPOSED AROUND SAID HEARTH SECTION; AND MEANS FOR FLOWING A FILM OF COOLING LIQUID OF SUBSTANTIAL THICKNESS OVER SUBSTANTIALLY THE ENTIRE EXTERNAL SURFACE OF THE HEARTH SECTION IN DIRECT CONTACT WITH THE GRAPHITE BLOCKS.