Potassium magnesium fertilizer
A process for producing potassium magnesium sulfate, comprising reacting sulfuric acid with potassium chloride and magnesium chloride at a temperature in a range comprised between about 100 and about 160° C., thereby producing potassium magnesium sulfate and hydrochloric acid, the sulfuric acid being reacted with potassium chloride and magnesium chloride simultaneously or sequentially.
1. A process for producing potassium magnesium sulfate, comprising reacting sulfuric acid with potassium chloride and magnesium chloride at a temperature in a range between about 100 and about 160° C., thereby producing potassium magnesium sulfate and hydrochloric acid.
2. The process of claim 1 , wherein the sulfuric acid is simultaneously reacted with the potassium chloride and the magnesium chloride.
3. The process of claim 1 , wherein the sulfuric acid is reacted with the potassium chloride and the magnesium chloride sequentially.
4. The process of claim 3 , wherein the sulfuric acid is reacted with the potassium chloride, thereby producing potassium hydrogen sulfate; and then the magnesium chloride is added, thereby yielding potassium magnesium sulfate.
5. The process of claim 1 , wherein the potassium chloride is in the form of potash.
6. The process of claim 1 , wherein at least part of the magnesium chloride is produced by acid leaching of a serpentine ore or a laterite ore with hydrochloric acid.
7. The process of claim 1 , wherein at least part of the magnesium chloride is in the form of a 30% magnesium chloride in water.
8. The process of claim 1 , wherein at least part of the magnesium is provided by reacting sulfuric acid with magnesium oxide.
9. The process of claim 8 , wherein the reaction of sulfuric acid with magnesium oxide is subsequent to the reaction of sulfuric acid with potassium chloride.
10. The process of claim 8 , further comprising adjusting a K/Mg ratio of the potassium magnesium sulfate by adding magnesium oxide to the potassium chloride and magnesium chloride.
11. The process of claim 2 , wherein said at least part of the potassium chloride and at least part of the magnesium chloride are in the form of carnallite.
12. The process of claim 11 , wherein the carnallite is in solution in water.
13. The process of claim 1 , wherein the potassium magnesium sulfate has a K/Mg ratio of 2:2.
14. The process of claim 1 , wherein the potassium magnesium sulfate has a K/Mg ratio of 2:1.
15. The process of claim 1 , wherein the potassium magnesium sulfate comprises less than about 1% of chlorine impurity.
16. The process of claim 1 , wherein the potassium magnesium sulfate comprises less than about 0.5% of chlorine impurity.
17. The process of claim 1 , wherein the sulfuric acid is an acid at 92 to 98% H 2 SO 4 .
18. The process of claim 17 , wherein the sulfuric acid is an acid at 92 to 94% H 2 SO 4 .
19. The process of claim 1 , comprising preheating the sulfuric acid to a temperature in the range between 100° C. and 160° C.
20. The process of claim 1 , wherein the sulfuric acid is reacted with the potassium chloride and the magnesium chloride at a temperature between about 100° C. and about 160° C.
21. The process of claim 1 , wherein the sulfuric acid is reacted with the potassium chloride and the magnesium chloride at a temperature between about 140° C. and about 160° C.
22. The process of claim 20 , wherein the sulfuric acid is reacted with the potassium chloride and the magnesium chloride during three hours.
23. The process of claim 1 , further comprising adsorbing the hydrochloric acid in water.
24. The process of claim 23 , wherein said adsorbing yields a 30 to 35% hydrochloric acid solution.
25. The process of claim 1 , further comprising recovering excess magnesium chloride in the form of a solution or a hexahydrate.
26. The process of claim 1 , further comprising using the hydrochloric acid to leach a serpentine ore, thereby producing a reaction mixture comprising silica and a mixture of chlorides of magnesium, iron, nickel and chromium.
27. The process of claim 26 , wherein the leaching is at a temperature between about 90° C. and about 110° C.
28. The process of claim 27 , wherein the serpentinic ore comprises between about 35 and about 41% weight of magnesium oxide.
29. The process of claim 28 , further comprising filtering the reaction mixture, thereby producing a liquid portion and a solid portion.
30. The process of claim 29 , further comprising recovering the magnesium chloride from the liquid portion.
31. The process of claim 30 , wherein the magnesium chloride is recovered from the liquid portion as a 20 to 30% magnesium chloride solution in water.
32. The process of claim 31 , wherein said magnesium chloride recovered from the liquid portion is a magnesium chloride produced by acid leaching of a serpentine ore with hydrochloric acid.
33. The process of claim 30 , further comprising:
i. recovering the silica from the solid portion; and
ii. dissolving the recovered silica in caustic at a temperature of about 230° C. under pressure, thereby producing sodium orthosilicate and waterglass.
34. The process of claim 1 , further comprising using the hydrochloric acid to leach magnesium oxide from a laterite ore.