Mixed metal compound
There is provided a method of producing a mixed metal compound comprising at least Mg 2+ and at least Fe 3+ having an aluminum content of less than 10000 ppm, having an average crystal size of less than 20 nm (200 A) comprising the steps of: (a) combining a Mg 2+ salt and a Fe 3+ salt with Na 2 CO 3 and NaOH to produce a slurry, wherein the pH of the slurry is maintained at from 9 5 to 1 1, and wherein the Na 2 CO 3 is provided at an excess of 0 to 4.0 moles than is required to complete the reaction (b) subjecting the slurry to mixing under conditions providing a power per unit volume of 0 03 to 1.6 kW/m 3 (c) separating the mixed metal compound from the slurry, to obtain a crude product having a dry solid content of at least 10 wt % (d) drying the crude product either by (i) heating the crude product to a temperature of no greater than 150° C. and sufficient to provide a water evaporation rate of 0.05 to 1 5 kg water per hour per kg of dry product, or (H) exposing the crude product to rapid drying at a water evaporation rate of 500 to 50000 kg water per hour per kg of dry product.
1. A mixed metal compound comprising at least Mg 2+ and at least Fe 3+ ,
wherein
the molar ratio of Mg 2+ to Fe 3+ is 2.5:1 to 1.5:1,
the mixed metal compound has an aluminium content of less than 10000 ppm,
the average crystal size of the mixed metal compound is from 10 to 20 nm (100 to 200 Å),
and the d50 average particle size of the mixed metal compound is less than 300 μm.
2. A mixed metal compound according to claim 1 wherein the d50 average particle size of the mixed metal compound is less than 200 μm.
3. A mixed metal compound comprising at least Mg 2+ and at least Fe 3+ ,
wherein
the molar ratio of Mg 2+ to Fe 3+ is 2.5:1 to 1.5:1,
the mixed metal compound has an aluminium content of less than 10000 ppm,
the average crystal size of the mixed metal compound is from 10 to 20 nm (100 to 200 Å),
and the water pore volume of the mixed metal compound is from 0.25 to 0.7 cm 3 /g of mixed metal compound.
4. A mixed metal compound according to claim 3 wherein water pore volume of the mixed metal compound is from 0.3 to 0.65 cm 3 /g of mixed metal compound.
5. A mixed metal compound according to claim 3 wherein the nitrogen pore volume of the mixed metal compound is from 0.28 to 0.56 cm 3 /g.
6. A mixed metal compound comprising at least Mg 2+ and at least Fe 3+ ,
wherein
the molar ratio of Mg 2+ to Fe 3+ is 2.5:1 to 1.5:1,
the mixed metal compound has an aluminium content of less than 10000 ppm, and
(a)(i) the average crystal size of the mixed metal compound is from 10 to 20 nm (100 to 200 Å)
and (a)(ii) the interlayer sulphate content of the compound is from 2 to 5 wt %; or
(b)(i) the average crystal size of the mixed metal compound is less than 20 nm (200 Å) and (b)(ii) the interlayer sulphate content of the compound is from 2.1 to 5 wt %.
7. A mixed metal compound according to claim 6 wherein the average crystal size of the mixed metal compound is from 12 to 20 nm (120 to 200 Å).
8. A mixed metal compound comprising at least Mg 2+ and at least Fe 3+ ,
wherein
the molar ratio of Mg 2+ to Fe 3+ is 2.5:1 to 1.5:1,
the mixed metal compound has an aluminium content of less than 10000 ppm, and
(a)(i) the average crystal size of the mixed metal compound is less than 20 nm (200 Å) and (a)(ii) the surface area is from 80 to 145 m 2 per gram of compound
or
(b)(i) the average crystal size of the mixed metal compound is from 10 to 20 nm (100 to 200 Å)
and (b)(ii) the surface area is from 40 to 80 m 2 per gram of compound.
9. A mixed metal compound according to claim 8 wherein the compound has a d50 average particle size of from 10 to 350 μm.
10. A mixed metal compound according to claim 8 wherein the compound has a d50 average particle size of from 10 to 100 μm.
11. A mixed metal compound according to claim 8 wherein the compound releases magnesium in an amount less than 0.15 mmol magnesium/g compound, when the compound is mixed with 40 mM phosphate buffer solution (pH 4) at 37.5° C. and shook for 30 minutes.
12. A mixed metal compound according to claim 8 wherein the water pore volume of the mixed metal compound is from 0.25 to 0.7 cm 3 /g of mixed metal compound.
13. A compound according to claim 1 wherein the compound is of the formula
M II 1-x M III x (OH) 2 A n− y .m H 2 O
wherein M III is one or more bivalent metals and is at least Mg 2+ ;
M III is one or more trivalent metals and is at least Fe 3+ ;
A n− is one or more n-valent anions and is at least CO 3 2− ;
x/Σyn is from 1 to 1.2
0<x≦0.4,
0<y≦1 and
0<m≦10.
14. A compound according to claim 13 wherein x/Σyn is from 1.05 to 1.15.
15. A compound according to claim 13 wherein x/Σyn is 1.
16. A compound according to claim 1 wherein the compound has an aluminium content of less than 30 ppm.
17. A compound according to claim 1 wherein the interlayer sulphate content of the compound is from 2 to 5 wt %.
18. A compound according to claim 1 wherein the compound has a d50 average particle size of less than 100 μm.
19. A compound according to claim 1 wherein the compound has a d50 average particle size of 5 to 50 μm.
20. A compound according to claim 1 wherein the compound has a d50 average particle size of approximately 5 μm.
21. A compound according to claim 1 wherein the water pore volume of the mixed metal compound is from 0.25 to 0.7 cm 3 /g of mixed metal compound.
22. A compound according to claim 1 wherein the compound has a dry solid content of at least 20 wt %.
23. A compound according to claim 3 wherein the compound is of the formula
M II 1-x M III x (OH) 2 A n− y .m H 2 O
wherein M II is one or more bivalent metals and is at least Mg 2+ ;
M III is one or more trivalent metals and is at least Fe 3+ ;
A n− is one or more n-valent anions and is at least CO 3 2− ;
x/Σyn is from 1 to 1.2
0<x≦0.4,
0<y≦1 and
0<m≦10.
24. A compound according to claim 6 wherein the compound is of the formula
M II 1-x M III x (OH) 2 A n− y .m H 2 O
wherein M II is one or more bivalent metals and is at least Mg 2+ ;
M III is one or more trivalent metals and is at least Fe 3+ ;
A n− is one or more n-valent anions and is at least CO 3 2− ;
x/Σyn is from 1 to 1.2
0<x≦0.4,
0<y≦1 and
0<m≦10.
25. A compound according to claim 8 wherein the compound is of the formula
M II 1-x M III x (OH) 2 A n− y .m H 2 O
wherein M II is one or more bivalent metals and is at least Mg 2+ ;
M III is one or more trivalent metals and is at least Fe 3+ ;
A n− is one or more n-valent anions and is at least CO 3 2− ;
x/Σyn is from 1 to 1.2
0<x≦0.4,
0<y≦1 and
0<m≦10.
26. A compound according to claim 3 wherein the compound has a dry solid content of at least 20 wt %.
27. A compound according to claim 6 wherein the compound has a dry solid content of at least 20 wt %.
28. A compound according to claim 8 wherein the compound has a dry solid content of at least 20 wt %.
29. A compound according to claim 6 wherein the water pore volume of the mixed metal compound is from 0.25 to 0.7 cm 3 /g of mixed metal compound.
30. A pharmaceutical composition comprising a mixed metal compound as defined in claim 1 and optionally one or more pharmaceutically acceptable adjuvants, excipients, diluents or carriers.
31. A pharmaceutical composition according to claim 30 in the form of a tablet, capsule or granule.
32. A pharmaceutical composition comprising a mixed metal compound as defined in claim 3 and optionally one or more pharmaceutically acceptable adjuvants, excipients, diluents or carriers.
33. A pharmaceutical composition according to claim 32 in the form of a tablet, capsule or granule.
34. A pharmaceutical composition comprising a mixed metal compound as defined in claim 6 and optionally one or more pharmaceutically acceptable adjuvants, excipients, diluents or carriers.
35. A pharmaceutical composition according to claim 34 in the form of a tablet, capsule or granule.
36. A pharmaceutical composition comprising a mixed metal compound as defined in claim 8 and optionally one or more pharmaceutically acceptable adjuvants, excipients, diluents or carriers.
37. A pharmaceutical composition according to claim 36 in the form of a tablet, capsule or granule.