Process for making nano-sized and micro-sized precipitate particles

1. A process of making nano-sized or micro-sized precipitate particles, the process comprising the steps of:

mixing, in a reaction zone at a high gravity level, a metal salt solution with a precipitant solution to form a precipitate, said precipitate being at least one of a metal chalcogenide, metal hydroxide and metal oxide; and

applying a shear force to said mixing solutions in said reaction zone during said mixing step, wherein said shear force and the conditions within said reaction zone form said micro-sized or nano-sized precipitate particles in said reaction zone, wherein said shear force precipitates particles having a narrow particle size distribution.

2. A process according to claim 1 , further comprising the step of:

ageing the nano-sized metal precipitate particles.

3. A process according to claim 2 , wherein said ageing step is undertaken under conditions to form substantially crystalline nano-sized or micro-sized particles.

4. A process according to claim 1 , comprising the step of selecting said metal salt solution from the group consisting of metal acetate salt, metal halide salt, metal nitrate salt, metal sulphate salt, metal phosphate salt, hydrates and mixtures thereof.

5. A process according to claim 4 , comprising the step of selecting said metal of said metal salt from the group consisting of alkali metals, alkaline earth metals, transition metals and metals from the main groups of the Periodic Table of Elements.

6. A process according to claim 1 , comprising the step of selecting a base as the precipitant solution.

7. A process according to claim 6 , wherein the base is an oxygen-containing base.

8. A process according to claim 7 , comprising the step of selecting said oxygen-containing base from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal hydrogen carbonates, ammonia solution, organic base and mixtures thereof.

9. A process according to claim 1 , comprising the step of selecting a metal chalcogenide salt solution as precipitant solution.

10. A process according to claim 9 , wherein the anion of said metal chalcogenide salt is selected from the group consisting of sulphides, HS − , Se 2− , SeO 3 2− , Te 2− , TeO 3 2 , their hydrates and mixtures thereof.

11. A process according to claim 1 , wherein the step of applying said shear force comprises the step of agitating said mixing solutions in said reaction zone.

12. A process according to claim 1 , wherein said shear force creates flow conditions within said reaction zone having a Reynolds Number of about 2000 to about 200000.

13. A process according to claim 1 , comprising the step of providing a surfactant in said mixing solution, said surfactant selected from the group consisting of anionic surfactants, cationic surfactants, non-ionic surfactants, polymeric surfactants and mixtures there of.

14. A process according to claim 13 , comprising the step of selecting the concentration of said surfactant from about 0.05% to about 10% by weight of mixture.

15. A process according to claim 1 , comprising the step of adding a particle dispersant to said mixing solution.

16. A process according to claim 1 , comprising the step of forming said nano-sized or micro-sized precipitate particles with a general formula MaXb, wherein

M is a transition metal selected from the group consisting of group IB, group IIB, group IVA and group VIIB of the Periodic Table of Elements; and

X is oxygen or a chalcogen;

a is an integer of 1, 2 or 3;

b is an integer of 1, 2, 3, 4 or 5; and

wherein combinations of a and b are such that the overall charge of the compound MaXb is zero.

17. A process according to claim 1 , comprising the step of:

injecting a gas into said reaction zone during said applying step.

18. A process according to claim 1 , wherein said high gravity level is selected from the group consisting of about 100 to about 15000 m·s-2, about 500 to about 2000 m·s-2, about 1000 to about 5000 m·s-2, and about 800 to about 5000 m·s-2.

19. A system for making nano-sized or micro-sized precipitate particles, the system comprising:

a reactor having a mixture of a metal salt solution and a precipitant solution which react to form a precipitate, said precipitate being at least one of a metal chalcogenide, metal hydroxide and metal oxide; and

an agitator comprising a packed bed for agitating said mixture in said reactor to apply a shear force at a high gravity level to said mixing solutions under conditions to form nano-sized or micro-sized precipitate particles having a narrow particle size distribution.

20. A reactor for making nano-sized precipitate particles, the reactor comprising:

a reaction zone containing a mixture of a metal salt solution and a precipitant solution which react to form a precipitate, said precipitate being at least one of a metal chalcogenide, metal hydroxide and metal oxide; and

an agitator comprising a packed bed for agitating said mixture in said reaction zone to apply a shear force at a high gravity level to said mixing solutions under conditions to form nano-sized precipitate particles having a narrow particle size distribution.