Patent ID: 6921520

Claim:
A process for upgrading phosphatic feedstock prepared from raw phosphate ore, said process comprising the steps: (a) heating said phosphate ore having a F/P 2 O 5 weight ratio of about 0.105 to the temperature range of 2200° F. to 2500° F. in a rotary kiln, a traveling-grate kiln, a shaft kiln or a combination of a traveling-grate kiln and a rotary kiln, to volatilize fluorine and obtain a F/P 2 O 5 weight ratio of about 0.097; (b) combining the heated phosphate ore from step (a) with anhydrous monocalcium phosphate, reducing carbon, and silica to form a mixture; (c) heating the mixture from step (b) at a temperature in the range of 2600° F. to 2730° F. in an electric furnace in the absence of air to form a gaseous mixture comprising carbon monoxide, elemental phosphorus, and hydrogen plus calcium silicate slag and ferrophosphorus; (d) contacting the gaseous mixture comprising carbon monoxide, elemental phosphorus, and hydrogen from step (c) with water to condense elemental phosphorus forming a liquid mixture of water, yellow phosphorus, and phosphorus sludge and a gaseous mixture of carbon monoxide and hydrogen; (e) washing the liquid mixture of water, yellow phosphorus, and phosphorus sludge from step (d) with water thereby coalescing particles of yellow phosphorus and obtaining white phosphorus, phosphorus sludge, and a gaseous mixture of carbon monoxide and hydrogen; (f) burning the gaseous mixture of carbon monoxide and hydrogen from step (e) as a fuel; (g) oxidizing the phosphorus sludge from step (e) with air to obtain P 2 O 5 ; (h) combining the P 2 O 5 from step (g) with water to obtain orthophosphoric acid solution; (I) mixing the orthophosphoric acid solution from step (h) with beneficiated phosphate ore in a cone mixer to obtain a slurry and discharging said slurry on a conveyor belt; (j) reacting said orthophosphoric acid solution with said beneficiated phosphate ore while on the conveyor belt of step (I) thus forming a monolithic mass of monocalcium phosphate monohydrate; (k) heating the monocalcium phosphate monohydrate from step (j) to at least 225° F. to volatilize water of hydration and excess water to obtain anhydrous monocalcium phosphate; and (I) combining the anhydrous monocalcium phosphate from step (k) with the heated phosphate ore, reducing carbon, and silica in step (b) to upgrade feedstock for smelting in an electric furnace.