Process Economics Program Report No. 8C

WET PROCESS PHOSPHORIC ACID

(August, 1982)

Abstract

Three processes to produce wet process phosphoric acid are

evaluated. The dihydrate process, once the undisputed leader, is now,

as a result of rising energy and raw material prices, no more economic

than hemihydrate and hemihydrate-dihydrate processes. The optimum

choice is likely to depend on the specific location, energy costs, type

of rock, and end product application.

The upgrading of wet process phosphoric acid to commercial grade

phosphoric acid by solvent extraction appears economical relative to

producing the latter grade in new facilities for furnace acid.

Rowever, because of the depressed state of the electric furnace

phosphorus industry, new commercial grade phosphoric acid capacity will

probably not be required before the mid 1980s.

Uranium extraction from wet process phosphoric acid, which was

potentially a profitable adjunct to wet process phosphoric acid plant

OperatiOnS in 1978 at a U308 price of $45/lb, is now economically

borderline at a U308 price of $24-$28/1b. Adaptation of the extraction

process to recover more than one metal, or its integration with wet

process acid upgrading operations, may help to improve overall

profitability.

PEP'80 CEH

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Report No. 8C

WET PROCESS PHOSPHORIC ACID

SUPPLEMENT C

by GEORGE E. HADDELAND

August 1982

A private report by the

PROCESS ECONOMICS PROGRAM

Menlo Park, California 94025

For detailed marketing data and information, the reader is

referred to one of the SRI programs specializing in marketing

research. The CHEMICAL ECONOMICS HANDBOOK Program covers

most major chemicals and chemical products produced in the

United States and the WORLD PETROCHEMICALS Program covers

major hydrocarbons and their derivatives on a worldwide basis.

In addition, the SRI DIRECTORY OF CHEMICAL PRODUCERS services

provide detailed lists of chemical producers by company, prod-

uct, and plant for the United States and Western Europe.

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CONTENTS

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

......... 3

......... 4

......... 4

......... 5

Production, Prices, and Raw Materials ... Phosphoric Acid Processes ......... Technology ................ Economics ................

Purification of Wet Process Phosphoric Acid to Industrial Grade ............ Technology ................ Economics ................

Uranium Recovery from Wet Process Phosphoric Technology ................ Economics ................

......... 7

......... 7 0

Acid ............... 1; ......... 10 ......... 11

3 INDUSTRY STATUS ....................... 15

Phosphoric Acid Production .................. 15 Phosphoric Acid Price .................... 19 Raw Material Prices ..................... 19 Sulfur ........................... 19 Phosphate Rock ....................... 27

Declining Quality of Florida Rock .............. 29

4 PROCESS CHEMISTRY AND ENERGY ................. 31

Phosphate Rock Dissolution .................. 31 Liquid Membrane Process for Uranium Extraction ........ 33 Energy Conservation in Wet Process Phosphoric Acid Manufacture ....................... 34

5 WET PROCESS PHOSPHORIC ACID ................. 37

Recent Developments ..................... 39 Dihydrate Processes .................... 39 Hemihydrate/Dihydrate Processes .............. 42 Hemihydrate Processes ................... 50

Dihydrate Process ...................... 60 Process Description .................... 60 Process Discussion ..................... 64 Cost Estimates ....................... 64

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CONTENTS

5 WET PROCESS PHOSPHORIC ACID (continued)

Hemihydrate/Dihydrate Process ................ Process Description ................... Process Discussion .................... 77

Cost Estimates ...................... 78 Hemihydrate Process ..................... 86 Process Description .................... 86 Process Discussion .................... 90 Cost Estimates ...................... 90

Discussion of Wet Process Phosphoric Acid Costs ....... 98 Conclusion ......................... 100

6 PHOSPHORIC ACID PURIFICATION ................ 103

Purification Technology ................... 104 Solvent Extraction Methods ................ 104 Chemical and Physical Methods ............... 119

Process Description ..................... 128 Process Discussion ..................... 133 Cost Estimates ....................... 133 Capital Costs ....................... 133 Production Costs ..................... 134 Discussion of Costs .................... 135

7 RECOVERY OF URANIUM FROM WET PROCESS PHOSPHORIC ACID .... 145

Technology ......................... 146 Patents....'.................. ; .... 152 Process Description ..................... 160 Process Discussion ..................... 165 Cost Estimates ....................... 166 Capital Costs ...................... 166 Production Costs ..................... 166 Discussion of Costs .................... 167

8 RECOVERY OF OTHER METALS FROM PHOSPHATE ROCK ........ 175

Vanadium .......................... 177 Rare Earths ......................... 178 Conclusions ....... ; ................. 178

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CONTENTS

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APPENDIX A DESIGN AND COST BASIS . . . . . . . . . . . . . . 179

APPENDIX B PHYSICAL AND THERMAL DATA . . . . . . . . . . . . 183

APPENDIX C ANALYSIS AND SPECIFICATIONS ........... 187

APPENDIX D CORROSION, WASTE DISPOSAL, AND POLLUTION CONTROL ..................... 189

CITED REFERENCES ........................ 195

PATENT REFERENCES ........................ 207

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ILLUSTRATIONS

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3.1 World Production of Phosphoric Acid . . . . . . . . . . . . 16

3.2 Phosphoric Acid Price History . . . . . . . . . . . . . . . 26

4.1 Effect of Reaction Conditions on Crystal Form of Calcium Sulfate . . . . . . . . . . . . . . 32

5.1 Occidental Chemical's Hemihydrate Process . . . . . . . . . 53

5.2 Wet Process Phosphoric Acid by the Dihydrate System Flow Sheet . . . . . . . . . . . . . . . . . . . . . . . . 211

5.3 Wet Process Acid by the Dihydrate System Estimated Capital Investment as a Function of Plant Design Capacity . . . . . . . . . . . . . . . . . . . 68

5. 4 Wet Process Phosphoric Acid by the Dihydrate System Value of Product P2O5 as a Function of Plant Design Capacity, Stream Factor, and Phosphate Rock and Sulfuric Acid Costs . . . . . . . . . . . . . . . . . . 72

5.5 Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Flow Sheet . . . . . . . . . . . . . . . . . . . . . . . . 213

5.6 Wet Process Phosphoric Acid by the Hemihydrate/ Dihydrate System Estimated Capital Investment as a Function of Plant Design Capacity and Value of Product P205 at Various Capacities and Stream Factors . . . . . . . . . 85

5.7 Wet Process Phosphoric Acid by the Hemihydrate System Flow Sheet . . . . . . . . . . . . . . . . . . . . . . . . 217

5.8 Wet Process Phosphoric Acid by the Hemihydrate System Estimated Capital Investment as a Function of Plant Design Capacity and the P2O5 Product Value at Various Capacities and Stream Factors . . . . . . . . . 97

5.9 Value of Uet Process Phosphoric Acid by Dihydrate, Hemihydrate, and Hemihydrate/Dihydrate Systems Value of Product P205 as a Function of Steam Value . . . . 101

6.1 Flow Diagram and Performance Data for Solvent Extraction of Phosphoric Acid . . . . . . . . . . . 106

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ILLUSTRATIONS

6.2 Purification of Wet Process Phosphoric Acid By Solvent Extraction Flow Sheet......................... 219

7.1 Processes to Recover Uranium from Wet Process Phosphoric Acid Flow Sheet......................... 221

7.2 Recovery of Uranium from Wet Process Phosphoric Acid Flow Sheet......................... 223

7.3 Recovery of Uranium from Wet Process Phosphoric Acid Product Value and Net Production Cost as a Function of Plant Size . . . . . . . . . . . . . . . . 174

B.l Phosphorus Pentoxide Recoveries at 25-35OC as a Function of the Solvent/Acid Volume Ratio and the Number of Extraction Stages . . . . . . . . . . . . . . 184

B.2 Uranium Extraction Coefficients for DEPA/TOPO Agents in n-Dodecane as a Function of Temperature . . . . . . . . . 185

B.3 Uranium Extraction Coefficients at 25'C for DEPA/TOPO Agents in n-Dodecane as a Function of TOP0 Concentration . . . . . . . . . . . . . . . . . . . . . . . 186

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TABLES

2.1 Capital and Production Costs for Making Wet Process Phosphoric Acid . . . . . . . . . . . . . . . . . 6

2.2 Capital and Production Costs for Purification of Wet Process Phosphoric Acid . . . . . . . . . 9

2.3 Capital and Production Costs for Recovery of Uranium from Wet Process Phosphoric Acid . . . . 13

3.1 Wet Process Phosphoric Acid Producers in the United States . . . . . . . . . . . . . . . . . . . . 17

3.2 Major Wet Process Phosphoric Acid Producers Outside the United States . . . . . . . . . . . . . . . . . . 20

3.3 Recent Sulfur Price History . . . . . . . . . . . . . . . . . 27

3.4 Distribution by Grade of Marketable Phosphate Rock from Florida and North Carolina . . . . . . . . . . . . . . . 29

5.1 Wet Process Phosphoric Acid by the Dihydrate Process Patent Summary . . . . . . . . . . . . . . . . . . . . . . . 43

5.2 Wet Process Phosphoric Acid by a Combination Hemihydrate/Dihydrate Process . . . . . . . . . . . . . . . . 51

5.3 Wet Process Phosphoric Acid by the Hemihydrate Process Patent Summary . . . . . . . . . . . . . . . . . . . . . . . 56

5.4 Wet Process Phosphoric Acid by the Dihydrate System Major Equipment . . . . . . . . . . . . . . . . . . . . . . . 61

5.5 Wet Process Phosphoric Acid by the Dihydrate System Utilities Summary . . . . . . . . . . . . . . . . . . . . . . 62

5.6 Wet Process Phosphoric Acid by the Dihydrate Process Stream Flows . . . . . . . . , . . . . . . . . . . . . . . . 63

5.7 Wet Process Phosphoric Acid by the Dihydrate System Total Capital Investment . . . . . . . . . . . . . . . . . . 66

5.8 Wet Process Phosphoric Acid by the Dihydrate System Capital Investment by Section . . . . . . . . . . . . . . . . 67

5.9 Wet Process Phosphoric Acid by the Dihydrate System Production Costs . . . . . . . . . . . . . . . . . . . . . . 69

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TABLES

5.10

5.11

5.12

5.13

5.14

5.15

5.16

5.17

5.18

5.19

5.20

5.21

Wet Process Phosphoric Acid by the Dihydrate System Direct Operating Costs by Section (Thousand $/Yr.) . . . . . 71

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Major Equipment . . . . . . . . . . . . . . . . . . . . . . 74

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Utilities Summary . . . . . . . . . . . . . . . . . . . . . 75

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Stream Flows . . . . . . . . . . . . . . . . . . . . . . . . 76

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Total Capital Investment . . . . . . . . . . . . . . . . . . 80

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Capital Investment by Section . . . . . . . . . . . . . . . 81

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Production Costs . . . . . . . . . . . . . . . . . . . . . . 82

Wet Process Phosphoric Acid by the Hemihydrate/Dihydrate System Direct Operating Costs by Section (Thousand $/Yr) . . . . . 84

Wet Process Phosphoric Acid by the Hemihydrate System MajorEquipment . . . . . . . . . . . . . . . . . . . . . . 88

Wet Process Phosphoric Acid by the Hemihydrate System Utilities Summary . . . . . . . . . . . . . . . . . . . . . 88

Wet Process Phosphoric Acid by the Hemihydrate System Stream Flows . . . . . . . . . . . . . . . . . . . . . . . . 89

Wet Process Phosphoric Acid by the Hemihydrate System Total Capital Investment . . . . . . . . . . . . . . . . . . 92

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5.23

5.24

6.1

6.2

6.3

6.4

6.5

6.6

6.7

6.8

6.9

Wet Process Phosphoric Acid by the Hemihydrate System Capital Investment by Section . . . . . . . . . . . . . . . 93

Wet Process Phosphoric Acid by the Bemihydrate System Production Costs . . . . . . . . . . . . . . . . . . . . . 94

Wet Process Phosphoric Acid by the Hemihydrate System Direct Operating Costs by Section (Thousand $/Yr) . . . . . 96

Production of Furnace Acid and Phosphorus in the United States . . . . . . . . . . . . . . . . . . . 104

Purification of Wet Process Phosphoric Acid by Solvent Extraction Patent Summary . . . . . . . . . . . . . . . . . . . . . . 108

Purification of Wet Process Phosphoric Acid by Chemical Methods Patent Summary . . . . . . . . . . . . . . . . . . . . . . 120

Removal of Metal Impurities from Wet Process Phosphoric Acid Patent Summary . . . . . . . . . . . . . . . . . . . . . . 125

Removal of Organic Impurities from Wet Process Phosphoric Acid Patent Summary . . . . . . . . . . . . . . . . . . . . . . 127

Purification of Wet Process Phosphoric Acid by Solvent Extraction Major Equipment . . . . . . . . . . . . . . . . . . . . . . 129

Purification of Wet Process Phosphoric Acid by Solvent Extraction Utilities Summary . . . . . . . . . . . . . . . . . . . . . 130

Purification of Wet Process Phosphoric Acid by Solvent Extraction Stream Flows , . . . . . . . . . . . . . . . . . . . . . . 131

Purification of Wet Process Phosphoric Acid by Solvent Extraction Total Capital Investment . . . . . . . . . . . . . . . . . 137

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TABLES

6.10 Purification of Wet Process Phosphoric Acid by Solvent Extraction Capital Investment by Section . . . . . . . . . . . . . . . 138

6.11 Purification of Wet Process Phosphoric Acid by Solvent Extraction Production Costs . . . . . . . . . . . . . . . . . . . . . 139

6.12 Purification of Wet Process Phosphoric Acid by Solvent Extraction Direct Operating Costs by Section (Thousand $/Yr) . . . . . 141

6.13 Capital and Operating Cost Estimates for Electric Furnace Phosphorus . . . . . . . . . . . . . . 142

6.14 Capital and Operating Cost Estimates for Furnace Phosphoric Acid . . . . . . . . . . . . . . . . 143

7.1 Uranium Content of Various Phosphate Rocks and of the Phosphoric Acid Produced Therefrom . . . . . . . 145

7.2 Plants for the Recovery of Uranium from Wet Process Phosphoric Acid . . . . . . . . . . . . . . . . 147

7.3 Characteristics of Uranium Solvents , . . . . . . . . . . . 148

7.4 Recovery of Uranium from Wet Process Phosphoric Acid Patent Summary . . . . . . . . . . . . . . . . . . . . . . 153

7.5 Recovery of Uranium from Wet Process Phosphoric Acid Major Equipment . . . . . . . . . . . . . . . . . . . . . . . 162

7.6 Recovery of Uranium from Wet Process Phosphoric Acid Utilities Summary . . . . . . . . . . . . . . . . . . . . . 163

7.7 Recovery of Uranium from Wet Process Phosphoric Acid Stream Flows . . . . . . . . . . . . . . . . . . . . . . . 164

7.8 Recovery of Uranium from Wet Process Phosphoric Acid Total Capital Investment . . . . . . . . . . . . . . . . . 169

7.9 Recovery of Uranium from Wet Process Phosphoric Acid Capital Investment by Section . . . . . . . . . . . . . . . 170

7.10 Recovery of Uranium from Wet Process Phosphoric Acid Production Costs . . . . . . . . . . . . . . . . . . . . . 171

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7.11 Recovery of Uranium from Wet Process Phosphoric Acid Direct Operating Costs by Section (Thousand $/Yr) . . . . . 173

8.1 Concentration of Trace Minerals and Their Value in Comercial Phosphate Rocks in the United States . . . . 176

c.1 Wet Process Phosphoric Acid Compositions . . . . . . . . . 187

c.2 Technical and Food Grade Acid Specifications and Analysis . . . . . . . . . . . . . . . . 188

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