Thermal treatment of phosphate rock

Patent · Tue Oct 27 04:00:00 EST 1987

OSTI ID:5889698

Mair, A D

An improved process for double-stage calcining organic matter contaminated phosphatic apatite rock of the mineral class generally known as francolites is described. The improved process results in the effecting of an intermediate phosphate rock calcine in a form eminently suitable for the subsequent acidulation thereof to wet-process phosphoric acid. The improved process results in substantially minimizing requirements for application of external energy thereto, and the improved process comprises: (a) initially thermally treating the rock within the temperature range of 340/sup 0/C to 410/sup 0/C for a period of time ranging from 30 to 120 minutes; (b) subsequently thermally treating the resulting initially thermally treated rock within the temperature range of 640/sup 0/C to 710/sup 0/C for a period of time ranging from 5 to 40 minutes. The improved process is characterized by the fact that the double-stage calcining of the organic matter contaminated phosphatic apatite rock is effected in such a manner so as to produce therefrom a resulting calcined phosphate rock product having substantially all the congeneric organic matter eliminated therefrom, having acid-evolved sulfide formation therefrom substantially minimized, and maintaining a substantial porosity thereof to thereby effect a surface area of at least 2 m/sup 2//g.

• Assignee: Tennessee Valley Authority, Muscle Shoals, AL
• Patent Number(s): US 4702896
• OSTI ID: 5889698
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACIDIFICATION
CALCINATION
CHALCOGENIDES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DECOMPOSITION
HEATING
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MINERALS
ORGANIC MATTER
PHOSPHATE MINERALS
PHOSPHORIC ACID
PYROLYSIS
SULFIDES
SULFUR COMPOUNDS
THERMOCHEMICAL PROCESSES
YIELDS