Fluoride removal from wet-process phosphoric acid reactor gases

219 Pages·2009·8.19 MB·English

FLUORIDE REMOVAL FROM WET-PROCESS
PHOSPHORIC ACID REACTOR GASES
By
JOHN MUNRO CRAIG
ADISSERTATIONPRESENTEDTOTHEGRADUATECOUNCILOF
THEUNIVERSITYOF FLORIDA
IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FORTHE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1970
UNIVERSITYOFFLORIDA
111111111
3 1262085524733
ACKNOWLEDGMENTS
The author wishes to express his appreciation to
the many people and firms who made this project possible.
Gratitude is extended to the members of the
writer's supervisory committee, Dr. R. S. Sholt.es,
chairman, Dr. R. 0. McCaldin, Dr. J. E, Singley, and
Dr. D. T. Williams.
Special recognition is due to the many companies
who provided the items necessary for this work. The
following are singled out for mentioning Tampa Electric
:
Company, Tri-Coat, Agrico Chemical Corporation, Airetron
Engineering Corporation, American Air Filter Company,
Inc., Peabody Engineering Corporation, and the Occidental
Chemical Company. Special recognition is due Mr. P.
Flanagan, Occidental Chemical Company, for his effores
in coordinating the author's requirements with the main-
tenance and operating departments at the plant site.
The author is indebted to Mr. H. McGraw for his
efforts in erecting the research equipment and to Mrs. J.
Hunt for typing this manuscript.
The author wishes to express deep appreciation
to the Department of Health, Education, and Welfare,
National Air Pollution Control Administration for financing
his graduate studies and to the Agrico Chemical Company
for partial funding of this research project.
The author wishes to thank the many University
of Florida faculty and staff members, whose names are
too numerous to list, for their kind and patient assis-
tance
.
In conclusion, the author,would like to thank
his wife, Jo, and his children, John, Linda, and Kimi
for their patience and understanding during this period
in their lives.
TABLE OE CONTENTS
Page
ACKNOWLEDGMENTS Li
VLI
LIST OE TABLES
LIST OF FIGURES viii
KEY TO MAIN ABBREVIATIONS xi-1
ABSTRACT xil-1
CHAPTER
I. INTRODUCTION
II. PHOSPHATE INDUSTRY IN FLORIDA 6
Phosphate Fertilizer Manufacturing
Processes
Geology
Mining £
Washing and Flotation Q*
Beneficiation }2
AFceirdtilMiazneurfacMtaunruifnagcturing jl|°
Elemental Phosphorous Manufactur-
ing 18
Air Pollution Associated With the
Phosphate Industry ^1
Fluoride Toxicity 24
Vegetation Damage *j>
Cattle Damage ^
Human Health Damage ^
Governmental Controls J4
III. WET-PROCESS PHOSPHORIC ACID 37
History 37
Prior to 1900 37
-11990300 ttoo 11993608 ^f1>
iv
Page
Fundamental Principles of the Dihycirate
Process 43
Raw Materials 45
Process Chemistry 49
Process Technology 52
Fluoride Evolution 57
IV. ABSORPTION THEORIES AND EMPIRICAL
RELATIONSHIPS 60
Absorption Theories 60
General Principles 61
Two-Film Theory 66
Penetration Theory 68
Surface Renewal Theory 68
Film Penetration Theory 69
Absorption with Chemical Reaction 69
Fluoride Absorption 72
General Design Concepts 72
Absorption in the Cyclonic Spray
Chamber 79
Absorption in the Venturi 81
Absorption in the Baffle Plate
Impingement Column 82
Correlation of Scrubber Efficien-
cies 83
V. THE EXPERIMENT 86
,
Experiment Design 87
Operating Variables 87
Preliminary Investigations, 89
Response 90
Replication of Experiments ...... 90
Equipment Description 90
Wet-Process Phosphoric Acid Plant 93
Liquid Handling System 95
Gas Handling System 100
Cyclonic Spray Chamber Scrubber 103
.
Venturi - Cyclonic Scrubber 105
Impingement Baffle Plate Column 105
Variable Throat Venturi . 108
Instrumentation 109
Experimental and Analytical Procedures 110
Preparation for the Study 110
Page
Typical Experimental Run Ill
Fluoride Sampling and Analysis .. 114
VI. RESULTS OF THE EXPERIMENT 134
Cyclonic Spray Chamber 152
Venturi - Cyclonic Scrubber 156
Baffle Plate Impingement Column 153
Variable Throat Venturi . 160
VII. CONCLUSIONS AND RECOMMENDATIONS 163
APPENDIX I 170
APPENDIX II 1^7
LIST OF REFERENCES 191
BIOGRAPHICAL SKETCH 200
LIST OF TABLES
Table Page
FLUORIDE EVOLUTION ACCORDING TO SPECHT
1
AND CALACETO 23
2 FLUORIDE EMISSIONS ACCORDING TO HUFFSTUTLER .... 24
3 TYPICAL COMPOSITION OF COMMERCIAL GRADES OF
FLORIDA PHOSPHATE ROCK 46
4 TYPICAL COMPOSITION OF OCCIDENTAL PHOSPHATE
ROCK 46
5 FLUORIDE BALANCE IN SWIFT & CO. WET-PROCESS
PHOSPHORIC ACID PLANT 56
6 LIQUID HANDLING SYSTEM ORIFICES 99
7 GAS HANDLING SYSTEM ORIFICES 102
8 OCCIDENTAL LABORATORY ANALYSIS 125
9 STATISTICAL ANALYSIS OF CALIBRATION CURVE DATA .126
10 SPRAY CHAMBER EXPERIMENTAL DATA SCRUBBING
LIQUID - WELL WATER ..171
11 SPRAY CHAMBER EXPERIMENTAL DATA SCRUBBING
LIQUID - GYPSUM POND WATER 173
12 VENTURI EXPERIMENTAL DATA SCRUBBING LIQUID -
WELL WATER 175
13 VENTURI EXPERIMENTAL DATA SCRUBBING LIQUID -
GYPSUM POND WATER 177
14 BAFFLE PLATE IMPINGEMENT COLUMN SCRUBBING
LIQUID - WELL WATER 179
15 BAFFLE PLATE IMPINGEMENT COLUMN SCRUBBING
LIQUID - GYPSUM POND WATER 181
16 VARIABLE THROAT VENTURI EXPERIMENTAL DATA
SCRUBBING LIQUID - WELL WATER 183
17 VARIABLE THROAT VENTURI EXPERIMENTAL DATA
SCRUBBING LIQUID - GYPSUM POND WATER 135
vii
2
LIST OF FIGURE'S
Figure Page
TYPICAL PHOSPHATE ROCK PROCESSING
1
FACILITY 10
2 WASHER AND FLOTATION PLANT FLOW DIAGRAM 11
3 TYPICAL PHOSPHATE ROCK BENEFICATION FLOW
DIAGRAM 13
4 TYPICAL ACID-FERTILIZER MANUFACTURING COMPLEX
FLOW DIAGRAM 15
5 TYPICAL CONTACT SULFURIC ACID PROCESS FLOW
DIAGRAM 16
6 TYPICAL WET-PROCESS PHOSPHORIC ACID FLOW
DIAGRAM 17
7 TYPICAL TRIPLE-SUPERPHOSPHATE FACILITY FLOW
DIAGRAM 19
8 TYPICAL DIAMMQNIUM PHOSPHATE FACILITY FLOW
DIAGRAM 20
9 TYPICAL ELEMENTAL PHOSPHORUS FACILITY FLOW
DIAGRAM 22
10 RELATION OF CONCENTRATION AND DURATION OF
EXPOSURE TO EFFECTS OF ATMOSPHERIC FLUORIDE
ON TOMATO PLANTS 28
11 PRECIPITATION AND STABILITY OF CALCIUM SULFATES
IN PHOSPHORIC ACID 51
1 EQUILIBRIUM DIAGRAM 62
13 DIFFUSION OF A THROUGH STAGNANT B 64
14 INTERFAC1AL CHARACTERISTICS IN PHYSICAL
ABSORPTION 70
15 INTERFACIAL CHARACTERISTICS IN ABSORPTION
WITH CHEMICAL REACTION 71
Vlll
Figure Page
16 VAPOR PRESSURE OF HYDROFLUORIC ACID OVER
DILUTE AQUEOUS SOLUTIONS 77
17 VAPOR PRESSURE OF SILICON TETRAFLUORIDE OVER
AQUEOUS SOLUTIONS OF FLUOSILICIC ACID 77
18 EQUIPMENT TRAILER FROM ROOF OF ACID PLANT
REACTOR TANK 91
19 SIDE VIEW OF EQUIPMENT TRAILER 92
20 FLOW DIAGRAM OCCIDENTAL WET-PROCESS PHOSPHORIC
ACID PLANT 94
21 OCCIDENTAL WET-PROCESS PHOSPHORIC ACID PLANT
EFFLUENT CONTROL SYSTEM 96
22 SCHEMATIC DIAGRAM OF LIQUID SYSTEM 97
23 LIQUID STORAGE TANK TRAILER 98
24 SCHEMATIC DIAGRAM OF GAS HANDLING SYSTEM 101
25 DIAGRAMMATICVIEW OF CYCLONIC SPRAY CHAMBER ... 104
26 DLAGRAMKATICVIEW OF VENTURI 106
27 DIAGRAMKATICVIEW OF IMPINGEMENT BAFFLE PLATE
COLUMN 107
28 FRACTION OF FREE FLUORIDE AS A FUNCTION OF
SOLUTION pH, WHERE HYDROGEN ION IS THE ONLY
COMPLEXING SPECIES 118
29 EFFECT OF pH ON ELECTRODE RESPONSE (SODIUM
FLUORIDE STANDARD) 118
30 CALIBRATION CURVE USING 2 PERCENT SODIUM
ACETATE SOLUTION 121
31 FLUORIDE SAMPLING TRAIN 127
32 EFFECT OF LIQUID/GAS RATIO ON FLUORIDE REMOVAL
EFFICIENCY IN SPRAY CHAMBER 135
33 EFFECT OF TOTAL CONTACTING POWER ON NUMBER OF
TRANSFER UNITS IN SPRAY CHAMBER 136
34 EFFECT OF LIQUID/GAS RATIO ON NUMBER OF
TRANSFER UNITS FOR SPRAY CHAMBER USING WELL
WATER 137
IX