Abstract Colemanite ore is treated to prepare pure calcined colemanite which is substantially free of the ore gangue. The ore is first dried to remove all uncombined water, then calcined with a stream of hot gas at a temperature sufficient to fracture the colemanite crystals into small particles which are selectively picked up from the ore by the gas stream and carried in the gas stream in which the final calcination of the colemanite takes place. The calcined colemanite particles are then separated from the gas stream. The method can be carried out with two rotary kilns mounted in tandem and tilted for gravity feed. A burner and blower are mounted at the discharge end of the lower kiln or calciner, and a feed chute with a gas lock connects the feed end of the calciner to the discharge end of the upper kiln. An exhaust stack leads from the ore inlet end of the calciner to a cyclone separator, the gas exiting from the separator into a conduit connected to the ore discharge end of the upper drier, and the balance of the ore discharges from the discharge end of the calciner. A feed chute and exhaust stack are connected to the feed end of the upper drier.
An apparatus for treating colemanite ore, including colemanite crystals and aggregate material, including: a drying zone having inlet and outlet ends; means for supplying ore to the inlet end of said drying zone through an air lock device adapted to permit the introduction of the ore but preventing any substantial discharge of air from the drying zone through said air lock device; a calcining zone having inlet and outlet ends; means for transferring ore from the outlet end of said drying zone into the inlet end of said calcining zone through a second air lock device adapted to permit the introduction of the ore into the calcining zone but preventing any substantial discharge of air from the calcining zone through said second air lock device; means at the outlet end of said calcining zone for blowing air through said calcining zone at a temperature and velocity sufficient for calcination of colemanite crystals in said zone and the removal of calcined colemanite therefrom; conveyor means between the inlet end of said calcining zone and the outlet end of said drying zone for passing said air current therebetween and cooling said air current to a temperature suitable for drying ore in said drying zone, said conveyor means including separating means for separating calcined colemanite from the air current after said air current leaves said calcining zone and before it enters said drying zone; and means for discharging said air current from the inlet end of said drying zone.
Claim 2
Dependent Claim
16 words
An apparatus as defined in claim 2 wherein said drying and calcining zones comprise rotary kilns.
Claim 3
Dependent Claim
16 words
An apparatus according to claim 3 wherein said separating means includes at least one cyclone separator.