Process for the recovery of phosphate from phosphate rock
AssigneeAgrium Inc.
InventorsLeslie L. Carstens, Nick P. Wynnyk
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Abstract
There is disclosed a wet process for the recovery of phosphate from phosphate rock which comprises leaching finely divided particles of phosphate rock with a protic acid at a temperature and for a time that favours dissolution, into a leachate, of the phosphate in relation to an impurity, and, isolating the leachate. An appropriate combination of particle size, leach time and leach temperature can achieve high phosphate recovery while reducing the amount of impurities.
Claims62
A process for selective solubilization of phosphate in relation to an impurity other than calcium in phosphate rock comprising:
- (a) leaching finely divided particles of phosphate rock with a protic acid at a temperature and for a time that favours solubilization, into a leachate, of phosphate in relation to the impurity;
- and,
- (b) isolating the leachate from the impurity that is not solubilized;
- wherein:
- the finely divided particles of phosphate rock predominantly have a diameter of less than 200 microns;
- the temperature is between about −15° C. and about 150° C.;
- the time is between about 1 second to about 24 hours;
- and
- the time has a relationship to the temperature of substantially inverse correspondence.
A process for selective solubilization of phosphate in relation to an impurity other than calcium in phosphate rock comprising:
- (a) leaching finely divided particles of phosphate rock having a diameter of less than about 40 microns with sulphuric acid at a temperature from about 40° C. to about 70° C. for about 1 minute to about 5 minutes to favour solubilization, into a leachate, of phosphate in relation to the impurity;
- and,
- (b) isolating the leachate from the impurity that is not solubilized.
A process for separating phosphate from an impurity other than calcium in phosphate rock comprising leaching finely divided particles of phosphate rock with a protic acid at a temperature and for a time that favours retention of the impurity in a solid residue in relation to retention of the phosphate in the solid residue;
- wherein:
- the finely divided particles of phosphate rock predominantly have a diameter of less than 200 microns;
- the temperature is between about −15° C. and about 150° C.;
- the time is between about 1 second to about 24 hours;
- and
- the time has a relationship to the temperature of substantially inverse correspondence.
A process for separating phosphate from an impurity other than calcium in phosphate rock comprising leaching finely divided particles of phosphate rock having a diameter of less than about 40 microns with a protic acid at a temperature from about 40° C. to about 70° C. for about 1 minute to about 5 minutes to favour retention of the impurity in a solid residue in relation to retention of the phosphate in the solid residue.
A process for selective recovery of phosphate in relation to an impurity in phosphate rock comprising:
- (a) separating phosphate rock into a first fraction and a second fraction wherein the first fraction consists essentially of particles of phosphate rock, predominantly having a particle size of less than 200 microns and the second fraction consists essentially of particles of phosphate rock predominantly having a particle size of greater than 200 microns;
- (b) leaching the particles of the first fraction with a protic acid at a temperature and for a time that favours solubilization into a first leachate of phosphate in relation to the impurity and that favours retention of the impurity in a first solid residue in relation to retention of phosphate in the first solid residue, wherein the temperature is between about −15° C. and about 150° C., the time is between about 1 second to about 24 hours, and the time has a relationship to the temperature of substantially inverse correspondence;
- (c) digesting the particles of the second fraction with a protic acid to form a second leachate containing phosphate and a second solid residue;
- (d) separating the first leachate from the first solid residue and separating the second leachate from the second solid residue;
- and
- (e) combining the first and second leachate.
Dependencies are inferred from the claim text.