Table 1

Chemical composition of phosphogypsum %"

Table 2

Pretreatment scheme of phosphogypsum"

Fig.1

XRD pattern of phosphogypsum"

Fig.2

SEM images of phosphogypsum"

Fig.3

TG-DSC curve of phosphogypsum"

Fig.4

Appearance of phosphogypsum calcined at different temperature"

Fig.5

Effect of calcination pretreatment on pH of phosphogypsum treated as raw materials"

Fig.6

Comparative effect of calcination pretreatment on total phosphorus and water-soluble phosphorus in phosphogypsum"

Fig.7

Comparative effect of calcination pretreatment on total fluorine and water-soluble fluorine in phosphogypsum"

Fig.8

Effect of calcination pretreatment on organic matter and sulfur trioxide content in phosphogypsum"

Table 3

Proportion of three-phase components of phosphogypsum at different calcination temperature"

Fig.9

Histogram of three-phase components of phosphogypsum at different calcination temperature"

Table 4

Effect of calcination temperature on water consumption and setting time of phosphogypsum standard consistency"

Table 5

Effect of calcination temperature on mechanical properties of phosphogypsum"

Table 6

Effect of microwave calcination temperature on physical properties of phosphogypsum"

Fig.10

Effect of microwave calcination temperature on water consumption and setting time of phosphogypsum standard consistency"

Fig.11

Effect of microwave calcination temperature on mechanical properties of phosphogypsum"

Table 7

Effect of washing times on physical properties of phosphogypsum"

Table 8

Effect of washing times on mechanical properties of phosphogypsum"

Fig.12

Effect of washing times on impurity content and setting time"

Fig.13

Effect of washing times on mechanical properties of phosphogypsum"

Table 9

Effect of ball milling time on physical properties of phosphogypsum"

Fig.14

Effect of ball milling time on water consumption and setting time of phosphogypsum standard consistency"

Fig.15

Effect of ball milling time on mechanical properties of phosphogypsum"