Phosphate recovery by acid retardation

Patent metadata

Field	Value
Publication number	US-10843941-B2
Application number	US-201515124564-A
Country	US
Kind code	B2
Filing date	Mar 6, 2015
Priority date	Mar 10, 2014
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A method of recovering phosphoric acid from process water includes directing a process water stream having a pH and a first concentration of phosphoric acid and at least one salt into a vessel, contacting the process water stream with a sorption agent in the vessel, the sorption agent adsorbing phosphoric acid from the process water, withdrawing a first effluent including a first concentration of the at least one salt and a second concentration of phosphoric acid from the vessel, and contacting the sorption agent including the phosphoric acid with water, at least a portion of the phosphoric acid desorbing from the ion exchange media into the water to form a second effluent having a third concentration of phosphoric acid.

First claim

What is claimed is:

1. A method, comprising:
directing a process water stream having a pH and a first concentration of phosphoric acid and at least one salt into a vessel;
controlling the pH of the process water stream by the addition of an acid and/or a base to a pH of about 2 to about 3 ;
contacting the pH-controlled process water stream with a sorption agent comprising a strong base anion exchange resin in the vessel, the sorption agent adsorbing phosphoric acid from the pH-controlled process water stream;
withdrawing a first effluent including a first concentration of the at least one salt and a second concentration of phosphoric acid from the vessel; and
desorbing at least a portion of the phosphoric acid from the sorption agent by contacting the sorption agent with water for a period of time effective to form a second effluent having a third concentration of phosphoric acid and a phosphoric acid purity of greater than about 80%.

2. The method of claim 1 , wherein the third concentration of phosphoric acid is higher than the second concentration of phosphoric acid.

3. The method of claim 1 , wherein the at least one salt comprises one of a sulfate and a hexafluorosilicate.

4. The method of claim 1 , further comprising concentrating the phosphoric acid in the second effluent by reverse osmosis.

5. The method of claim 1 , further comprising concentrating the phosphoric acid in the second effluent by evaporation.

6. The method of claim 1 , further comprising recycling at least a portion of the first effluent into the vessel.

7. The method of claim 6 , further comprising combining the at least a portion of the first effluent with the pH-controlled process water stream.

8. A method, comprising:
directing a process water stream having a pH and a first concentration of phosphoric acid and at least one salt into a vessel;
controlling the pH of the process water stream by the addition of an acid and/or a base to a pH of about 1 to about 1 . 5 ;
contacting the pH-controlled process water stream with a sorption agent comprising a strong base anion exchange resin in the vessel, the sorption agent adsorbing phosphoric acid from the pH-controlled process water stream;
withdrawing a first effluent including a first concentration of the at least one salt and a second concentration of phosphoric acid from the vessel; and
desorbing at least a portion of the phosphoric acid from the sorption agent by contacting the sorption agent with water for a period of time effective to form a second effluent having a third concentration of phosphoric acid.

9. The method of claim 8 , wherein the third concentration of phosphoric acid is higher than the second concentration of phosphoric acid.

10. The method of claim 8 , wherein the at least one salt comprises one of a sulfate and a hexafluorosilicate.

11. The method of claim 9 , further comprising concentrating the phosphoric acid in the second effluent.

12. The method of claim 8 , further comprising combining the at least a portion of the first effluent with the pH-controlled process water stream.

13. The method of claim 8 , wherein the second effluent has a recovered phosphoric acid concentration of up to about 2% by weight.

Assignees

• Evoqua Water Tech Llc

Inventors

• Mallmann Thomas Kenneth
• Higgs Justin W
• Workman Kenneth Ray

Classifications

• C02F2209/005

  Processes using a programmable logic controller [PLC] · CPC title

• C01B25/18

  Phosphoric acid · CPC title

• C01B25/234

  Purification; Stabilisation; Concentration (purification concomitant with preparation C01B25/22; preparation involving solvent-solvent extraction C01B25/46) · CPC title

• C02F2209/06

  pH · CPC title

• C02F2101/105

  Phosphorus compounds · CPC title