Method
There is provided a method of producing a mixed metal compound comprising at least Mg 2+ and at least Fe + having an aluminium 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 method of producing a mixed metal compound comprising
at least Mg 2+ and at least Fe 3+
having an aluminium content of less than 10000 ppm,
having an average crystal size of less than 20 nm (200 Å)
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 11, 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
(ii) 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.
2. A method 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 (II)
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.
3. A method according to claim 2 wherein x/Σyn is from 1.05 to 1.15.
4. A method according to claim 2 wherein x/Σyn is 1.
5. A method according to claim 1 wherein the molar ratio of Mg 2+ to Fe 3+ is 2.5:1 to 1.5:1.
6. A method according to claim 1 wherein the compound has an average crystal size of from 10 to 20 nm (100 to 200 Å).
7. A method according to claim 1 wherein the compound has an aluminium content of less than 100 ppm.
8. A method according to claim 1 wherein the mixed metal compound comprises sulphate as an interlayer anion and the interlayer sulphate content of the compound is from 1.8 to 5 wt %.
9. A method according to claim 1 wherein the Na 2 CO 3 is provided at an excess of 2.0 to 4.0 moles than required to complete the reaction.
10. A method according to claim 1 wherein step (a) comprises:
(A) combining a Mg 2+ salt and a Fe 3+ salt with Na 2 CO 3 and NaOH to produce a slurry, wherein the slurry is maintained to a temperature between 15 and 30° C., and:
(i) wherein the pH of the slurry is maintained at from 9.5 to less than 9.8, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 5.0 moles than is required to complete the reaction; or
(ii) wherein the pH of the slurry is maintained at from 9.5 to less than 10, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 4.0 moles than is required to complete the reaction; or
(iii) wherein the pH of the slurry is maintained at from 9.5 to no greater than 10.1, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 2.7 moles than is required to complete the reaction; or
(iv) wherein the pH of the slurry is maintained at from 9.5 to 10.5, and wherein the Na 2 CO 3 is provided at an excess of from greater than 1.0 to no greater than 2.0 moles than is required to complete the reaction; or
(v) wherein the pH of the slurry is maintained at from greater than 9.5 to no greater than 11, and wherein the Na 2 CO 3 is provided at an excess of from 0.0 to no greater than 1.0 moles than is required to complete the reaction;
or step (a) comprises:
(B) combining a Mg 2+ salt and a Fe 3+ salt with Na 2 CO 3 and NaOH to produce a slurry, wherein the slurry is maintained to a temperature from 30 to 60° C., and:
(i) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 11, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 2 moles than is required to complete the reaction; or
(ii) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 10.5, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 2.7 moles than is required to complete the reaction; or
(iii) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 10, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 4 moles than is required to complete the reaction.
11. A method according to claim 1 wherein in step (b) the slurry is subjected to mixing under conditions providing a power per unit volume of 0.03 to 1.6 kW/m 3 while maintaining a slurry temperature of less than 65° C.
12. A method according to claim 1 wherein in step (b) the slurry conditions are controlled such that a d50 particle size distribution of at least 40 μm is provided.
13. A method according to claim 1 wherein in step (c) the mixed metal compound is separated from the slurry, to obtain a crude product having a dry solid content of at least 15 wt %.
14. A method according to claim 1 wherein in step (d) the crude product is dried 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.
15. A method according to claim 1 wherein in step (d) the crude product is dried by 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.
16. A method according to claim 1 wherein the crude product is washed prior to step (d).
17. A method according to claim 1 wherein the dried crude product is milled to a d50 average particle size of less than 200 μm.
18. A method according to claim 1 wherein the milled dried crude product has a water content of 1 to 10 wt % based on the total weight of the dried crude product.
19. A method according to claim 1 for the production of a mixed metal compound having a total heavy metal content of less than 15 ppm, a lead content less than 10 ppm, a chromium level less than 35 ppm and a sodium content (expressed as Na 2 O) of less than 1 wt %.
20. A method of producing a mixed metal compound comprising
at least Mg 2+ and at least Fe 3+
having an aluminium content of less than 10000 ppm,
having an average crystal size of less than 20 nm (200 Å);
the method comprising the step 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 slurry is maintained to a temperature between 15 and 30° C., and:
(i) wherein the pH of the slurry is maintained at from 9.5 to less than 9.8, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 5.0 moles than is required to complete the reaction; or
(ii) wherein the pH of the slurry is maintained at from 9.5 to less than 10, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 4.0 moles than is required to complete the reaction; or
(iii) wherein the pH of the slurry is maintained at from 9.5 to no greater than 10.1, and wherein the Na 2 CO 3 is provided at an excess of greater than 1.0 to no greater than 2.7 moles than is required to complete the reaction; or
(iv) wherein the pH of the slurry is maintained at from 9.5 to 10.5, and wherein the Na 2 CO 3 is provided at an excess of from greater than 1.0 to no greater than 2.0 moles than is required to complete the reaction; or
(v) wherein the pH of the slurry is maintained at from greater than 9.5 to no greater than 11, and wherein the Na 2 CO 3 is provided at an excess of from 0.0 to no greater than 1.0 moles than is required to complete the reaction;
or the method comprising the step of:
(b) combining a Mg 2+ salt and a Fe 3+ salt with Na 2 CO 3 and NaOH to produce a slurry, wherein the slurry is maintained to a temperature from 30 to 60° C., and:
(i) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 11, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 2 moles than is required to complete the reaction; or
(ii) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 10.5, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 2.7 moles than is required to complete the reaction; or
(iii) wherein the pH of the slurry is maintained at from greater than 9.5 to less than 10, and wherein the Na 2 CO 3 is provided at an excess of greater than 0 to less than 4 moles than is required to complete the reaction.
21. A mixed metal compound obtained or obtainable by the method of claim 1 .
22. A mixed metal compound according to claim 21 for use as a medicament.
23. A mixed metal compound according to claim 21 for binding phosphate.
24. A mixed metal compound according to claim 21 for use in the treatment of hyperphosphataemia.
25. A pharmaceutical composition comprising a mixed metal compound as defined in claim 21 and one or more pharmaceutically acceptable adjuvants, excipients, diluents or carriers.