Primary amine-containing polymers useful as scale inhibitors

1. A process for inhibiting scale produced during wet process phosphoric acid production, the process comprising:

adding a scale-inhibiting amount of a reagent comprising a primary amine-containing polymer, or salt thereof, to at least one stage of a wet process phosphoric acid production process,

wherein said primary amine-containing polymer comprises an A mer according to Formula (I):

where

R is H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, halide, or carboxyl;

R 1 is H, C 1 -C 6 alkyl, or C 2 -C 6 alkenyl;

R 2 is H or an A mer according to Formula (I);

R 3 is chosen from a direct bond or a C 1 -C 12 alkyl, C 2 -C 12 alkenyl, or a C 6 -C 12 aryl group; and

n is an integer chosen to provide a weight average molecular weight of the primary amine-containing polymer of at least 300 Daltons, and

wherein the percentage of primary amine in the polymer is from 30 mole % to 100 mole % based on the total percentage of mer units in the polymer.

2. A process according to claim 1 , wherein R and R 1 are H, and R 3 is a direct bond.

3. A process according to claim 1 , wherein the primary amine-containing polymer is a polyvinylamine homopolymer, or a salt thereof.

4. A process according to claim 1 , wherein R and R 1 are H, and R 3 is CH 2 .

5. A process according to claim 1 , wherein the primary amine-containing polymer is a polyallylamine homopolymer, or a salt thereof.

6. A process according to claim 5 , wherein the polyallylamine homopolymer salt is polyallylamine-hydrochloride.

7. A process according to claim 1 , wherein the primary amine-containing polymer further comprises a B mer.

8. A process according to claim 7 , wherein R 3 of said A mer is a direct bond, said B mer unit comprises a compound according to Formula (II):

wherein

R and R 1 are as defined for the A mer according to Formula (I);

R 4 is chosen from H or C 1 -C 4 alkyl;

R 5 is a direct bond or a C 1 -C 12 alkyl; C 2 -C 12 alkenyl, or a C 6 -C 12 aryl group;

R 6 is a C 1 -C 22 alkyl, C 2 -C 22 alkenyl, or C 6 -C 22 aryl group, which group is optionally substituted at one or more substitutable position

n is chosen from 30 mole % to 99 mole % based on the total percentage of mer units in the polymer; and

m is chosen from 1 mole % to 70 mole % based on the total percentage of mer units in the polymer.

9. A process according to claim 8 , wherein the B mer unit according to Formula (II) is

10. A process according to claim 7 , wherein the B mer is derived from a monomer selected from the group consisting of diallylamine, diallyldimethylammonium chloride; acrylamide; N-methylolacrylamide; N-(C 1 to C 22 )alkyl acrylamide, N,N-di-(C 1 to C 22 )alkyl acrylamide, hydroxy alkyl(meth)acrylamide, N-vinylformamide; N-(C 1 to C 22 )alkyl-N-vinylformamide, N-vinylacetamide, N-(C 1 to C 22 )alkyl-N-vinylacetamide, N-vinyl propionamide, N-(C 1 to C 22 )alkyl-N-vinyl propionamide, (meth)acrylic acid; the esters, nitriles, and amides of (meth)acrylic acid; vinyl acetate, vinyl propionate, vinyl alcohol, (C 1 to C 22 )alkyl vinyl ethers, vinylpyrrolidone; polyetheramine; and copolymers thereof.

11. A process according to claim 7 , wherein the B mer is N-vinylformamide, and the primary amine-containing polymer is a poly(vinylamine-co-vinylformamide) copolymer, or a salt thereof.

12. A process according to claim 7 , wherein the B mer is N-vinylacetamide and the primary amine containing polymer is a poly(vinylamine-co-vinylacetamide), or a salt thereof.

13. A process according to claim 7 , wherein the primary amine-containing polymer includes at least two B mer units.

14. A process according to claim 13 , wherein the primary amine-containing polymer is a poly(vinylamine-co-vinylformamide-co-diallyldimethylammonium chloride) terpolymer, or a salt thereof.

15. A process according to claim 13 , wherein said B mer units are N-(C 6 to C 22 )alkyl acrylamide and vinylformamide.

16. A process according to claim 15 , wherein the primary amine-containing polymer is a poly(vinylamine-co-vinylformamide-co-N-t-octylacrylamide) terpolymer, or a salt thereof.

17. A process according to claim 1 , wherein the primary amine-containing polymer is branched.

18. A process according to claim 1 , wherein the weight average molecular weight of the primary amine-containing polymer is from 300 Daltons to 300,000 Daltons.

19. A process according to claim 1 , wherein the percentage of primary amine in the polymer is from 45 mole % to 100 mole % based on the total percentage of mer units in the polymer.

20. A process according to claim 19 , wherein the percentage of primary amine in the polymer is from 55 mole % to 100 mole % based on the total percentage of mer units in the polymer.

21. A process according to claim 7 , wherein the percentage of primary amine in the polymer is from 45 mole % to 99 mole % based on the total percentage of mer units in the polymer.

22. A process according to claim 21 , wherein the ratio of primary amine in the polymer is from 60 mole % to 99 mole %.

23. A process according to claim 1 , wherein the scale produced contains at least one species of scale-forming ion selected from the group consisting of Na 2 SiF 6 ; K 2 SiF 6 ; CaSO 4 +2 H 2 O; CaSO 4 +½ H 2 O; CaSO 4 ; MgSiF 6 +6 H 2 O; Ca 3 (PO 4 ) 2 ; CaHPO 4 ; Si 2 F 6 ; CaSiF 6 +2 H 2 O; CaF 2 ; MgF 2 ; Mg 0.8 Al 1.5 F 6 +X H 2 O, wherein X is an integer ranging from 2 to 10; MgH 2 P 6 O 7 ; Al(PO 3 ) 3 ; NaK 2 AlF 6 ; Ca 3 (AlF 6 ) 2 +4 H 2 O; MgNaAlF 6 +2 H 2 O; and Ca 4 SO 4 AlSiF 13 +10 H 2 O.

24. A process according to claim 1 , wherein the reagent is added to any of the interstitial piping of the phosphoric acid production plant and/or to one or more stages of the phosphoric acid production process selected from the group consisting of the milling stage; the digesting stage; the filtering stage; the evaporation stage; and the clarifying stage.

25. A process according to claim 1 , wherein the scale-inhibiting amount of reagent added to the wet process phosphoric acid production process is from 0.5 g per ton to 5000 g per ton of phosphoric acid.