The bauxite-rare-rare earth minerals are formed by the clay in the calcareous laterite conversion and rare and rare earth minerals being absorbed and agglomerated during leaching and desilication in weathering period;and minerals conversion and sedimentation and rare and rare earth oxides being covered by the converted minerals in water soaking and desilication in sedimentation period.

According to the damage features of the fracture types and their developing patterns,and changing of mineral phase transformation under microscopic scale,it is concluded that the superposition between fracturing and explosive spalling plays a key role in the multi-layer damages of the lining concrete.

The influence of F~- on the phase transformation of alumina from metastable phase toα- alumina and microstructure ofα-alumina has been studied by TG/DSC,XRD,SEM measurements in this paper.

The phase transformation of carbon alpha-Al(OH)_3 powder in the calcine process between 200 ℃～1 500 ℃ was analyzed using D/Max-3BX beam diffraction meter.

It was discovered that MgO could restrain the phase transformation of metastable alumina to stable α-Al2O3 and change the crystallization habit of α-Al2O3.

The features of the phase transition for α-Al(OH) 3 powder silts in the calcination process from 200 ℃ to 1 500 ℃ have been studied by D/max-3BX-ray diffractometer,and the physical and chemical properties involved with spectfic surface area,angle of repose,apparent density,effective density,refractive index,whiteness and ignition loss and so on for calcinated product have been studied too.

The features of the phase transition for α-Al(OH) 3 powder silts in the calcination process from 200℃ to 1500℃ have been studied by D/max-3BX-ray diffractometer,and the physical and chemical properties involved with spectfic surface area,angle of repose,apparent density,effective density,refractive index,whiteness and ignition loss and so on for calcinated product have been studied too.