《AGGLOMERATION OF PHOSPHATE FINES FOR FURNACE USE》

Ⅰ．Introduction1

Ⅱ．Agglomeration by Nodulizing4

Nodulizing Plant Operations4

Nodulizing Tests and Results11

Development of Method for Removal of Kiln Rings14

Refractory Life17

Ⅲ．Agglomeration by Sintering18

Chronological Summary of TVA＇s Work on Sintering18

Small-Scale Investigations of the Sintering Process20

Equipment and Materials20

Teat Procedure22

Sintering of Unmilled Sand with Sinter Fines and Coke25

Rake Sand25

Bowl Sand26

Bird Sand26

Mixture of Bird and Bowl Sands26

Mixture of Washed Sand and Clayey Binders26

Sintering of Milled Sands,Sinter Fines,and Coke27

Phosphate Sands27

Sand-Matrix Mixtures28

Effects of Bed Depth and Draft29

Development of Pelletizing Equipment30

Effect of Moisture Content of the Feed Mixture31

Use of Sinter Fines and Dry Sand to Control Moisture32

Effects of Type,Proportion,and Particle Size of Fuel33

Application of Results35

Production of Sinter in Large-Scale Plant38

Description of Equipment38

Operation of Equipment42

Production of Sinter from Rake Sand46

Production of Sinter from Bird Sand47

Present Status of Sintering Process49

Ⅳ．Agglomeration by Extrusion50

Ⅴ．Agglomeration by Tumbling54

Equipment and Materials54

Factors Affecting the Formation of Pellets by Tumbling57

Effects of Type of Phosphate and Plasticizing Treatment57

Effect of Moisture Content of Feed61

Effects of Feed Rate to Tumbler and Speed of Tumbler61

Conversion of Tumbled Pellets into Furnace Charge62

Partial Drying of Pellets64

Pelletizing and Partial Drying in Tumbler65

Pelletizing and Partial Drying in Rotary Kiln65

Pelletizing in Tumbler and Partial Drying in Rotary Kiln67

Pelletizing in Tumbler and Partial Drying in Mesh-Belt Drier70

Calcination of Pellets70

Calcination of Tumbled Pellets in Rotary Kiln72

Calcination of Tumbled Pellets in a Shaft Kiln76

Equipment and Procedure76

Pilot-Plant Results80

Evaluation of Shaft-Kiln Calcination83

Ⅵ．Agglomeration by Briquetting84

Pilot-Plant Tests Using a Roll-Type Press84

Equipment,Procedure,and Materials84

Variables Affecting Briquet Production91

Effect of Moisture Content92

Effect of Phosphate Composition92

Effect of Pretreatment94

Effect of Applied Pressure96

Effect of Addition Agents98

Plant Tests Using Raw Briquets99

Use of Briquets in the Calcium Metaphosphate Furnaces99

Use of Briquets in the Fused Tricalcium Phosphate Furnace99

Production of Calcined Briquets101

Calcination in a Rotary Kiln101

Calcination in a Shaft Kiln102

Evaluation of Briquetting Process103

Ⅶ．Choice of Agglomeration Process105

Comparative Studies in TVA Furnaces105

Electric Reduction Furnace105

Fused Tricalcium Phosphate Furnace107

Calcium Metaphosphate Furnace108

Comparative Costs of Agglomerated Products108

Nodulizing Plant109

Sintering Plant109

Calcined Pellet Plant(Rotary Kiln)111

Calcined Pellet Plant(Shaft Kiln)111

Raw Briquet Plant112

Calcined Briquet Plant(Rotary Kiln)113

Plant Investment Costs and Production Capacities114

Process Requirements114

Physical Properties of the Agglomerates115

Comparative Ease or Difficulty of Production116

Storage of Agglomerates118

Choice of Processes119

Ⅷ．References121

APPENDIXES122

A．Product Comparison Procedures122

B．Description of Mixers Used for Preliminary Treatment of Raw Sand124

TABLES12

Ⅰ．Nodule Production Data12

Ⅱ．Composition and Screen Analysis of Nodules12

Ⅲ．Effect of Particle Size of Sand on Nodulizing Results13

Ⅳ．Boring Bar Operating Data17

Ⅴ．Chemical Composition of Phosphatic Materials Used in Small-Scale Sintering Tests22

Ⅵ．Rate of Furnaceable Sinter Production from Unmilled Raw Phosphates25

Ⅶ．Effect of Various Charge-Preparation Treatments on Production Rate of Furnaceable Sinter from Phosphate Sands28

Ⅷ．Effect of Milling on Rate of Furnaceable Sinter Production29

Ⅸ．Effect of Moisture Content of Feed Mixture on Rate of Furnace-able Sinter Production31

Ⅹ．Effect of Amount and Particle Size of Sinter Fines Recycled on Sinter Production Rate32

Ⅺ．Effect of Type of Dry Phosphate Used for Moisture Control on Production Rate33

Ⅻ．Effect of Proportion of Coal and Coke on Rate of Furnaceable Sinter Production33

ⅩⅢ．Sintering of Rake Sand in Plant Machine46

ⅩⅣ．Sintering of Bird Sand in Plant Machine47

ⅩⅤ．Average Chemical and Screen Analyses of Bird Sand Sinter49

ⅩⅥ．Chemical and Screen Analyses of Phosphatic Materials Used in Studies of Agglomeration by Tumbling56

ⅩⅦ．Effects of Type of Sand,Matrix Content,and Plasticizing Treat-ment on Production of Pellets by Tumbling59

ⅩⅧ．Effect of Wet-Pan Treatment on Particle Size of Phosphate Sand61

ⅩⅨ．Effect of Matrix Content on Characteristics of Pellets Produced and Partially Dried in Rotary Kiln66

ⅩⅩ．Results of Partial Drying of Pellets in Pilot-Plant Rotary Kiln67

ⅩⅪ．Effect of Feed Mixture,Plasticizing Treatment,and Method of Tumbling on Production of Partially Dried Pellets in Rotary Kiln69

ⅩⅫ．Effect of Size of Calcined Pellets on Their Strength71

ⅩⅩⅢ．Summary of Test Data on Pilot-Plant Pelletization and Rotary Kiln Calcination73

ⅩⅩⅣ．Size of Plus 6-Mesh Calcined Pellets Produced from Various Phosphatic Materials76

ⅩⅩⅤ．Operating Characteristics of Shaft Kiln at Various Production Rates80

ⅩⅩⅥ．Summary of Shaft Kiln Calcination of Pellets of Various Com-positions82

ⅩⅩⅦ．Chemical and Screen Analyses of Phosphatic Materials Used in Briquetting Studies91

ⅩⅩⅧ．Effects of Wet-Pan Treatment and Type of Matrix Used as Binder on Strength of Briquets Produced from Sand-Matrix Mixtures93

ⅩⅩⅨ．Effects of Addition of Tailing and Wet-Pan Treatment on Strength of Briquets Produced from Phosphate Sand94

ⅩⅩⅩ．Effect of Wet-Pan Treatment on Strength of Briquets Produced from Mixed Sand94

ⅩⅩⅪ．Comparison of Size Stability of Briquets Produced from Mixtures Processed in Edge Runner and Wet Pan95

ⅩⅩⅫ．Effect of Length of Edge Runner Treatment and Briquetting Pressure on Strength of Briquets97

ⅩⅩⅩⅢ．Data on Calcination of Briquets in a Rotary Kiln102

ⅩⅩⅩⅣ．Agglomeration Process Requirements115

ⅩⅩⅩⅤ．Physical Tests of Various Agglomerates116

ⅩⅩⅩⅥ．Production Considerations of Agglomeration Processes117

ⅩⅩⅩⅦ．Effect of Immersion in Water for 1 Hour on the Strength of Fired Agglomerates119

FIGURES5

1．Flow Diagram of Phosphate Nodulizing Process5

2．Layout of Nodulizing Plant6

3．Plant Nodulizing Kilns7

4．CO-Coal Burner10

5．Detail of Boring Bar for Removal of Kiln Rings16

6．Experimental Sintering Unit21

7．Typical Sintering Test Data24

8．Effects of Bed Depth and Draft on Rate of Furnaceable Sinter Production29

9．Effect of Fuel Particle Size on Rate of Sinter Production from Bird Sand35

10．Flow Diagram of Phosphate Sintering Process36

11．Layout of Sintering Plant37

12．General Arrangement of Feed End of Sintering Machine38

13．Equipment for Preparation of Sinter Feed39

14．Sintering Machine;View from Feed End41

15．Slotted-Type Sinter-Machine Grate46

16．Bird Sand Sinter;(a)View Showing Porous Structure,(b)View Showing Structure on Bottom of Sinter Bed48

17．Flow Diagram for Agglomeration by Tumbling54

18．Effect of Wet-Pan Treatment Time on Pellet Formation58

19．Effect of Proportion of Matrix in Feed on Pellet Formation59

20．Effect of Type of Wet Pan Used on Pellet Formation60

21．Effect of Moisture Content of Feed on Pellet Formation62

22．Effect of Feed Rate to Tumbler on Pellet Formation63

23．Effect of Moisture Content of Partially Dried Pellets on Resistance to Shattering and Abrasion64

24．Effect of Calcination Temperature and Tim on Strength of Pellets71

25．Calcined Pellets Discharging from Pilot-Plant Rotary Kiln77

26．Detail of Shaft Kiln Construction78

27．Flow of Materials and Gases Through Shaft Kiln Pilot Plant79

28．Methods of Feed Distribution for Shaft Kiln80

29．Experimental Briquetting Equipment85

30．Experimental Briquetting Machine87

31．Modified Wet Pan88

32．Modified Patterson Mixer89

33．Effect of Pressure and of Matrix on Strength of Briquets Made from Bird Sand—Matrix Mixtures97

34．Flow Diagram of Nodulizing Process110

35．Flow Diagram of Sintering Process110

36．Flow Diagram of Tumbling Process(Calcination in Rotary Kiln)111

37．Flow Diagram of Tumbling Process(Calcination in Shaft Kiln)112

38．Flow Diagram of Briquetting Process(Raw Product)113

39．Flow Diagram of Briquetting Process(Calcination in Rotary Kiln)114