By means of XRD

SEM and EDS

the phase transformation of calcium aluminate produced by calcination of secondary aluminum ash and calcium oxide at different proportions and different temperatures was investigated. The results indicate that at 1 200 ℃

the main phase is C

12

A

7

with a small amount of CA

2

formed. At 1 400 ℃

the main phase is C

12

A

7

with the absence of CA

2

and a small amount of CA formed. At 1 600 ℃

the main phase is CA. A

12

C

7

generated at 1 200 ℃ and 1 400 ℃ is cubic crystal system and belongs to stable C

12

A

7

. With the increase of temperature

the cell volume of C

12

A

7

in the clinker is increased. When the mass ratio of calcium oxide to secondary alumina ash are 0.9

1.0

1.1 and 1.2

and the mass ratio of secondary alumina ash to calcium oxide is between 0.9 and 1.2 at 1 350 ℃

the main phase is C

12

A

7

with a small amount of CA generated. The generated C

12

A

7

is stable

belonging to the cubic crystal system. With the increase of the mass ratio of calcium oxide to secondary aluminum ash

the content of C

12

A

7

is increased and the cell volume of C

12

A

7

in the clinker is increased firstly and then decreased. When the mass ratio of secondary aluminum ash to calcium oxide is 0.9

CA content reaches the maximum value. The Ca content in the mass ratio range of 1.0～1.2 is less than that of 0.9

which is little in this stage and hardly found by XRD.