Claims
- 1. A process for the beneficiation of phosphate ore containing a magnesia-rich carbonate-containing gangue and a silica-containing gangue comprising:
- (a) washing and classifying the phosphate ore to form a first fraction comprising primary fines and removing the primary fines from the phosphate ore;
- (b) subjecting the phosphate ore to controlled attrition during a period of not less than 5 minutes to remove at least a portion of the magnesia-rich carbonate-containing gangue from the phosphate ore particles;
- (c) separating the particles resulting from (b) into a fine and a coarse fraction; and
- (d) subjecting the coarse fraction obtained in (c) to a plurality of froth flotations to remove the remaining magnesia-rich carbonate-containing gangue and the silica-containing gangue and to recover a concentrated phosphate product, said froth flotations including a phosphate flotation, a silica flotation and an anionic carbonate flotation.
- 2. The process of claim 1 wherein step (b) is conducted so that the ratio d.sub.80 /d.sub.20 increases in the course of successive attrition by at least a factor of 1.05, d.sub.80 and d.sub.20 being the smallest mesh size through which 80% and 20%, respectively, of the particles will pass.
- 3. The process of claim 2 wherein step (b) is carried out by stirring in a tank a pulp containing from about 60% to 80% by weight of the ore with an agitator means so that the relative speed of any two ore particles in the pulp is less than 5 m/sec.
- 4. The process of claim 3 wherein the attrition is conducted for such a period that the mean residence time of the pulp in the tank is from 5 to 60 minutes.
- 5. The process of claim 3 wherein the rotational speed of the agitator means is so adjusted that the pulp passes from 1000 to 10,000 times per hour therethrough.
- 6. The process of claim 5 wherein the pulp passes from 2000 to 5000 times per hour through the agitator means.
- 7. The process of claim 3 wherein the rotational speed of the agitator means is so adjusted that the speed of the pulp while passing through the agitator means is from about 0.9 to 2.4 m/sec.
- 8. The process of claim 1, wherein step (d) comprises:
- (1) subjecting the coarse fraction to a first froth flotation step to separate phosphate particles from the gangue material;
- (2) subjecting the phosphate particles obtained in (1) to a second flotation step to remove residual silica; and
- (3) subjecting the phosphate particles obtained in (2) to a third anionic flotation step to remove the carbonate material.
- 9. The process of claim 8 wherein the first froth flotation step comprises conditioning the particles at a solids concentration of about 70% by weight, and a pH ranging from 9.0 to 10.0, for a period of 2 minutes and adding a collector comprising an aqueous emulsion of tall oil, domestic fuel, and soda; and separating the phosphates by froth flotation at a solids concentration ranging from 18 to 22% by weight, a pH of from 8.5 to 9.5, and for a period of from about 30 to 60 seconds.
- 10. The process of claim 8 wherein the second froth flotation step comprises flotation with an emulsion of an amine and kerosene at a pH of 7, a solids concentration ranging from about 18% to 20% by weight, and for a period of 2 minutes.
- 11. The process of claim 8 wherein the third froth flotation step comprises conditioning the particles with an aqueous emulsion of tall oil, domestic fuel, and soda for a period of 4 minutes, and separating the carbonates by flotation at a solids concentration ranging from about 8 to 22% by weight, a pH ranging from 4.5 to 6, and for a period of from 2 to 5 minutes.
- 12. The process of claim 11 wherein the pH is maintained by adding phosphoric acid.
- 13. A process for the beneficiation of phosphate ore containing a gangue containing carbonates and silica comprising:
- (a) subjecting the phosphate ore to a first froth flotation step to separate the phosphate from the gangue;
- (b) subjecting the phosphate concentrate obtained in (a) to a second froth flotation step to remove residual silica-containing gangue material;
- (c) subjecting the phosphate concentrate obtained in (b) to controlled attrition to remove at least a portion of the magnesia-rich carbonate-containing gangue from the phosphate ore particles;
- (d) separating the particles resulting from (c) into a fine and a course fraction; and
- (e) subjecting the coarse fraction obtained in (d) to a third anionic froth flotation step to remove the carbonate containing gangue and to recover a concentrated phosphate product.
- 14. The process of claim 13 wherein step (c) is conducted so that the ratio d.sub.80 /d.sub.20 increases in the course of successive attrition by at least a factor of 1.05, d.sub.80 and d.sub.20 being the smallest mesh size through which 80% and 20%, respectively, of the particles will pass.
- 15. The process of claim 14 wherein the first froth flotation step comprises conditioning the particles at a solids concentration of 70% by weight, and a pH ranging from 9.0 to 10.0, for a period of 2 minutes and adding a collector comprising an aqueous emulsion of tall oil, domestic fuel and soda, and separating the phosphates by froth flotation at a solids concentration ranging from 18 to 22% by weight, a pH of from 8.5 to 9.5, and for a period ranging from 30 to 60 seconds.
- 16. The process of claim 14 wherein the second froth flotation step comprises flotation with an emulsion of an amine and kerosene at a pH of 7, a solids concentration ranging from 18 to 22% by weight, and for a period of 2 minutes.
- 17. The process of claim 14 wherein the attrition of step (c) is carried out by stirring in a tank a pulp containing 60 to 80% by weight of the ore, with an agitator means, so that the relative speed of any two ore particles in the pulp is less than 5 m/sec.
- 18. The process of claim 17 wherein the attrition is conducted over such a period that the mean residence time of the pulp in the tank is from 20 to 60 minutes.
- 19. The process of claim 17 wherein the rotational speed of the agitator means is calculated in such a way that the pulp passes 1,000 to 10,000 times per hour therethrough.
- 20. The process of claim 19 wherein the pulp passes 2,000 to 5,000 times per hour through the agitator means.
- 21. The process of claim 17 wherein the rotational speed of the agitator means is calculated in such a way that the speed of the pulp while passing through the agitator means is 0.9 to 2.4 m/sec.
- 22. The process of claim 13 wherein the third froth flotation step comprises conditioning the particles with an aqueous emulsion of tall oil, domestic fuel, and soda for a period of 4 minutes, and separating the carbonate by flotation at a solids concentration of 18 to 22% by weight, a pH of from about 4.5 to 6, and for a period of 2 to 5 minutes.
- 23. The process of claim 22 wherein the pH is maintained by adding phosphoric acid.
- 24. A process for the beneficiation of phosphate ore containing a magnesia-rich carbonate-containing gangue and a silica-containing gangue comprising:
- (a) washing and classifying the phosphate ore to form a first fraction comprising primary fines and a fourth fraction a portion of which comprises coarse grains and removing the primary fines and the portion of the fourth fraction comprising coarse grains from the phosphate ore;
- (b) subjecting the phosphate ore to controlled attrition during a period of not less than 5 minutes to remove at least a portion of the magnesia-rich carbonate-containing gangue from the phosphate ore particles;
- (c) separating the particles resulting from (b) into a fine and a coarse fraction; and
- (d) subjecting the coarse fraction obtained in (c) to a plurality of froth flotations to remove the remaining magnesia-rich carbonate-containing gangue and the silica-containing gangue and to recover a concentrate phosphate product, said froth flotations including a phosphate flotation, a silica flotation and an anionic carbonate fraction.
- 25. The process of claim 24 wherein the phosphate ore subjected to controlled attrition comprises a second fraction and a third fraction having particle diameters within the range from about 100 to 1,000 microns.
- 26. The process of claim 24 wherein the primary fines have a particle diameter of less than about 100 microns.
- 27. The process of claim 24 wherein the portion of the fourth fraction remaining after the removal of the coarse grains is ground so that d.sub.80 ranges from about 250 to 500 microns and is then subjected to controlled attrition.
- 28. The process of claim 24 wherein the portion of the fourth fraction comprising coarse grains is the portion retained on an about 3 mesh screen.
Parent Case Info
This application is a continuation-in-part of application Ser. No. 204,520, filed Nov. 6, 1980, now abandoned.
US Referenced Citations (28)
Foreign Referenced Citations (4)
Number |
Date |
Country |
914572 |
Jun 1946 |
FRX |
914699 |
Jun 1946 |
FRX |
2320781 |
Mar 1977 |
FRX |
859155 |
Jan 1961 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
204520 |
Nov 1980 |
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