Table 1.

Chemical compositions of two kaolin samples (wt%).

Oxides	Wenchang Kaolin	Maoming Kaolin
SiO2	46.950	46.960
Al2O3	35.960	36.410
K2O	1.570	0.664
Fe2O3	1.070	0.784
TiO2	0.327	0.407
Na2O	0.236	0.134
Cl	0.219	0.016
CaO	0.089	0.053
CeO2	0.045	0.014
P2O5	0.044	0.318
La2O3	0.038	0.022
SO3	0.036	0.176
MgO	0.033	0.034
Nd2O3	0.021	0.004
ZrO2	0.015	0.006
ThO2	0.014	0.001
Rb2O	0.013	0.004
Ga2O3	0.009	0.008
Y2O3	0.008	0.002
Pr6O11	0.004	0.003
Nb2O5	0.004	0.001
ZnO	0.004	0.003
MnO	0.004	0.003
PbO	0.003	0.003
IrO2	0.002	0.002
GeO2	0.002	0.001
V2O5	0.001	0.007
NiO	0.001	0.002
Sc2O3	0.001	0.004
MoO3	-	0.011
Cr2O3	-	0.003
a LOI	13.28	13.95

^a LOI: loss on ignition at 980 °C.