The principal commercial deposits of phosphate rock exist in Florida, North Carolina, and Idaho, and to a lesser degree in Montana and Utah. Production of phosphate rock in Tennessee ended in 1991. Phosphate rock is mined, beneficiated, and either solubilized to produce wet-process phosphoric acid or smelted to produce elemental phosphoric acid or smelted to produce elemental phosphorous. Phosphoric acid is reacted with phosphate rock to produce the fertilizer triple superphosphate or with anhydrous ammonia to produce the ammonium phosphate fertilizers. Elemental phosphorus is the base for furnace-grade phosphoric acid, phosphorus pentasulfide, phosphorus pentoxide, and phosphorus trichloride. Approximately 90% of phosphate rock production is used for fertilizers and animal feed supplements and the balance for industrial chemicals.
U.S. phosphate rock production increased from 18 million metric tons in 1960 to 35 million metric tons in 1970 and peaked at 54 million metric tons in 1980. Consumption in 1990 was 44 million metric tons. Increasing tonnage of phosphate rock is used to produce higher value phosphatic fertilizers for the export market. Phosphate rock exports peaked in 1980 at 14 million metric tons and has declined to 6 million metric tons in 1990. Phosphate rock imports have historically been a minor factor in supply; however, in addition to small quantities of low-fluorine materials, phosphate rock imports in recent years increased to the .5-million-metric-ton level.
Phosphate rock prices in the 1960's were in the $5 to $6 per metric ton range, f.o.b. mine, and increased to the $20 to $25 per metric ton range, f.o.b. mine, in the 1980's.
The demand for phosphate rock as a nutrient for food production will vary throughout the world. The overall demand is forecast to increase in the 1%-to-2%-per-year range; however, in the agriculturally mature countries, the increase in demand will be closer to 1% per year.
The supply of phosphate rock is forecast to decline in the United States as existing mines in Florida are mined out and unfavorable economics discourage new mine development. World supply will be maintained from quality deposits in North Africa.
- Table 1 (TXT) -- U.S. phosphate rock historical data