Systems and methods for reducing formation of scale in phosphoric acid production

Patent metadata

Field	Value
Publication number	US-10759662-B2
Application number	US-201815918079-A
Country	US
Kind code	B2
Filing date	Mar 12, 2018
Priority date	Mar 12, 2018
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A method for reducing formation of scale in phosphoric acid production is provided herein. Phosphate-containing ore is combined with an acid to form an acidic slurry and the acidic slurry is processed to form an acidic stream. The method includes providing a scale inhibitor including an inorganic phosphate. The method further includes combining the scale inhibitor and at least one of the phosphate-containing ore, the acidic slurry, and the acidic stream, to reduce the formation of scale. A system for phosphoric acid production exhibiting a reduced formation of scale is also provided herein. The system includes a substrate having a surface in contact with at least one of the phosphate-containing ore, the acidic slurry formed from the phosphate-containing ore and the acid, and the acidic stream formed from the acidic slurry. The system including the scale inhibitor exhibits a reduced formation of scale on the surface.

First claim

What is claimed is:

1. A method for reducing formation of scale in phosphoric acid production, wherein a phosphate-containing ore is combined with an acid to form an acidic slurry and the acidic slurry is processed to form an acidic stream, the method comprising:
providing a scale inhibitor comprising;
an inorganic phosphate according to formula (I),
(XPO 3 ) m   (I)

wherein X is Na, K, H, or combinations thereof, and m is an integer having a value of at least 6,
an inorganic phosphate according to formula (II),
Y n+2 P n O 3n+1   (II)

wherein Y is Na, K, H, or combinations thereof, and n is an integer having a value of at least 6, or
a combination thereof;

combining the scale inhibitor and at least one of the phosphate-containing ore, the acidic slurry, and the acidic stream, to reduce the formation of scale.

2. The method of claim 1 , wherein the inorganic phosphate of formula (I) comprises sodium hexametaphosphate and wherein m of formula (I) is an integer having a value of 6.

3. The method of claim 1 , wherein the inorganic phosphate of formula (II) comprises sodium poly(phosphate) and wherein n of formula (II) is an integer having a value of 21.

4. The method of claim 1 , wherein the scale inhibitor further comprises:
an additional inorganic phosphate according to formula (III),
(ZPO 3 ) o   (III)

wherein Z is Na, K, H, or combinations thereof, and o is an integer having a value of no greater than 4;
an additional inorganic phosphate according to formula (IV),
Z p+2 P p O 3p+1   (IV)

wherein Z is Na, K, H, or combinations thereof, and p is an integer having a value of no greater than 4;
an organic phosphonate; or
combinations thereof.

5. The method of claim 4 , wherein the additional inorganic phosphate comprises tetrasodium pyrophosphate.

6. The method of claim 4 , wherein the organic phosphonate comprises 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethane 1,1-diphosphonic acid, bis(phosphonomethyl)aminotris(methylenephosphonic acid), bis(hexamethylene triamine penta (methylene phosphonic acid)), hexamethylenediaminetetra (methylene phosphonic acid), diethylene triamine pentamethylene phosphonic acid, or combinations thereof.

7. The method of claim 6 , wherein the organic phosphonate comprises bis(hexamethylene triamine penta (methylene phosphonic acid)), hexamethylenediaminetetra (methylene phosphonic acid), diethylene triamine pentamethylene phosphonic acid, 1-hydroxyethane 1,1-diphosphonic acid, or combinations thereof.

8. The method of claim 1 , wherein at least one of the acidic slurry and the acidic stream have an acid concentration in an amount of greater than about 10%.

9. The method of claim 1 , wherein at least one of the acidic slurry and the acidic stream have a temperature of at least about 20° C.

10. The method of claim 1 , wherein the phosphate-containing ore is combined with the acid in a digester to form the acidic slurry.

11. The method of claim 10 , wherein the step of combining the scale inhibitor is further defined as combining the scale inhibitor and the acidic slurry in the digester.

12. The method of claim 10 , wherein the step of combining the scale inhibitor is further defined as combining the scale inhibitor and the acidic slurry after the digester.

13. The method of claim 1 , wherein the acidic slurry is processed utilizing a filter to form the acidic stream and the acidic stream is further processed utilizing an evaporator.

14. The method of claim 13 , wherein the step of combining the scale inhibitor is further defined as combining the scale inhibitor and the acidic stream after the filter.

15. The method of claim 14 , wherein the step of combining the scale inhibitor is further defined as combining the scale inhibitor and the acidic slurry after the filter and before the evaporator.

16. The method of claim 1 , wherein the acid comprises sulfuric acid.

17. The method of claim 1 , wherein the scale comprises calcium sulfate.

18. A method for reducing formation of scale in phosphoric acid production, wherein a phosphate-containing ore is combined with an acid to form an acidic slurry and the acidic slurry is processed to form an acidic stream, the method comprising:
providing a scale inhibitor comprising;
sodium poly(phosphate) according to formula (II),
Na n+2 P n O 3n+1   (II)

wherein n is an integer having a value of 21, and
at least one of;
an additional organic phosphonate comprising bis(hexamethylene triamine penta (methylene phosphonic acid)), hexamethylenediaminetetra (methylene phosphonic acid), diethylene triamine pentamethylene phosphonic acid, 1-hydroxyethane 1,1-diphosphonic acid, or combinations thereof, and
an inorganic phosphate comprising tetrasodium pyrophosphate; and

combining the scale inhibitor and at least one of the phosphate-containing ore, the acidic slurry, and the acidic stream, to reduce the formation of scale.

Assignees

• Solenis Tech Lp

Inventors

• Bakeev Kirill N
• Dimaio Andrew M
• Shepherd Anthony M

Classifications

• C01B25/222 Primary

  with sulfuric acid, a mixture of acids mainly consisting of sulfuric acid or a mixture of compounds forming it in situ, e.g. a mixture of sulfur dioxide, water and oxygen · CPC title

• C01B25/2204

  Arrangements of vessels used in reacting phosphate-containing material in wet process · CPC title