# US 10,865,110 B2 · Compositions and processes for removing heavy metals from phosphoric acid solutions

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- Number: US 10,865,110 B2
- Document ID: US10865110B2
- Status: Granted
- Kind: B2
- Application number: 16/152,918
- Filed: 2018-10-05
- Published: 2019-04-11
- Granted: 2020-12-15
- Earliest claimed: 2017-10-08
- Assignees: Cytec Industries Inc.
- Applicants: Cytec Industries Inc.
- Inventors: Lei Zhang; Xueping Qiu; Rajesh Raitani
- Web page: https://patentgrep.com/patent/US10865110B2

## CPC

- C01B 25/238: Cationic impurities {, e.g. arsenic compounds}
- C01P 2006/80: Compositional purity
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Processes for removing/recovering heavy metal ions in solutions containing phosphoric acid by adding reagents having at least one organothiophosphorus compound and at least one surfactant to the solution during the wet-process phosphoric acid production process to form heavy metal complexes, and separating the heavy metal complexes from the solution are provided herein.

## Claims

### Claim 1

A process for removing heavy metal ions from a phosphoric acid solution containing said heavy metal ions, said process comprising
adding an effective amount of a reagent comprising an organothiophosphorus compound and a surfactant to the phosphoric acid solution to form heavy metal complexes, and
separating the heavy metal complexes from the phosphoric acid solution.

### Claim 2 (depends on 1)

A process according to claim 1, wherein said heavy metal ions are selected from the group consisting of cadmium, copper, arsenic, mercury, lead, and mixtures thereof.

### Claim 3 (depends on 1)

A process according to claim 1, wherein said heavy metal ion is cadmium.

### Claim 4 (depends on 1)

A process according to claim 1, wherein said organothiophosphorus compound is selected from the group consisting of organodithiophosphinic acid, organodithiophosphonic acid, organodithiophosphoric acid, organomonothiophosphinic acid, organomonothiophosphonic acid, organomonothiophosphoric acid, and their salts in the form of sodium, ammonium, or potassium, and mixtures thereof.

### Claim 5 (depends on 4)

A process according to claim 4, wherein said organothiophosphorus compound comprises mixtures of organodithiophosphinic acid, organodithiophosphoric acid, and their salts in the form of sodium, ammonium, or potassium.

### Claim 6 (depends on 4)

A process according to claim 4, wherein said organodithiophosphinic compound is sodium diisobutyl dithiophosphinate.

### Claim 7 (depends on 4)

A process according to claim 4, wherein said organodithiophosphoric compound is sodium diisobutyl dithiophosphate.

### Claim 8 (depends on 1)

A process according to claim 1, wherein said surfactant is selected from the group consisting of sulfosuccinates, arylsulfonates, alkyarylsulfonates, diphenyl sulfonates, olefin sulfonates, sulfonates of ethoxylated alcohols, petroleum sulfonates, sulfosuccinamates, alkoxylated surfactants, ester/amide surfactants, EO/PO block copolymers, and mixtures thereof.

### Claim 9 (depends on 8)

A process according to claim 8, wherein said surfactant is a sulfosuccinate.

### Claim 10 (depends on 9)

A process according to claim 9, wherein said sulfosuccinate compound is sodium dioctylsulfosuccinate.

### Claim 11 (depends on 8)

A process according to claim 8, wherein the surfactant is polyethyleneglycol ester.

### Claim 12 (depends on 11)

A process according to claim 11, wherein the polyethyleneglycol ester surfactant is chosen from polyethyleneglycol sorbitan monooleate or polyethyleneglycol sorbitol hexaoleate.

### Claim 13 (depends on 1)

A process according to claim 1, wherein the process is performed at a temperature from 0° C. to 120° C.

### Claim 14 (depends on 1)

A process according to claim 1, wherein the phosphoric acid solution has a concentration from 20% to 64% P2O5, and the process is performed at a temperature from 20° C. to 80° C.

### Claim 15 (depends on 1)

A process according to claim 1 further comprising adding an effective amount of a reducing agent to the phosphoric acid solution.

### Claim 16 (depends on 15)

A process according to claim 15, wherein said reducing agent is added prior to or together with the addition of the reagent.

### Claim 17 (depends on 15)

A process according to claim 15, wherein said reducing agent is selected from the group consisting of sodium hypophosphite, hydrazine, iron (II) sulfate, iron powder, and mixtures thereof.

### Claim 18 (depends on 17)

A process according to claim 17, wherein said reducing agent is sodium hypophosphite.

### Claim 19 (depends on 1)

A process according to claim 1 further comprising adding an effective amount of an adsorbent to the phosphoric acid solution.

### Claim 20 (depends on 19)

A process according to claim 19, wherein said adsorbent is selected from the group consisting of calcium sulfate, fluorosilicate, activated carbon, and mixtures thereof.

### Claim 21 (depends on 20)

A process according to claim 20, wherein said adsorbent is calcium sulfate particles.

### Claim 22 (depends on 1)

A process according to claim 1, wherein the process further comprises the step of filtering the phosphoric acid solution prior to adding the reagent.