The kinds and properties of anhydrite profile

                            The kinds and properties of anhydrite profile

Anhydrite Ⅱ also called | 3 type of anhydrite, or insoluble anhydrite (Insolustrongleanhydrite). It is, half water gypsum dihydrate gypsum and anhydrite Ⅲ after high temperature dehydration stable end product at room temperature. In the nature of the existence of stable natural anhydrite also is such. In addition, in 1971, Bensted waiting under 400 ~ 600 ℃ heating CaS (^ Ⅲ, found from the infrared absorption spectrum is different from the middle phase, called low temperature type of CaS (^ Ⅱ 7, the refractive index of 1. 54 ~ 1. 56, unlike previous anhydrite Ⅱ (high temperature type) as they are called the refractive index of 1. 54 ~ 1. 61, other cases of this phase is unclear.

Anhydrite I also called a anhydrite, is a high temperature above 1180 ℃ can exist under the condition of phase, gesso mill is lower than the temperature, anhydrite and I into anhydrite Ⅱ. So there is no hard plaster work at room temperature, and no practical significance.

In addition, according to a 1975 Eipeltauer and others reported that gypsum dihydrate gypsum powder production line in 840 ~ 860 ℃ under 40 ℃ after firing quenching can adsorption of water molecules, according to the tg-dta analysis may generate amorphous hydrates, and found that with known CaS (), ~ H: 0 is inconsistent with the system of compound X-ray diffraction peak. But the insufficient data of two papers, according to the insufficient, there is still room for many to explore.

To sum up, under the condition of atmospheric pressure can exist independently in only four, namely, half water gypsum dihydrate gypsum and anhydrite m and anhydrite Ⅱ. The fifth phase - anhydrite, can only be about 1180. C above can exist. The crystalline structure of the five phase has its own characteristics, using X-ray phase analysis to distinguish them. Variant (Modification) recognized seven, namely in half water gypsum and anhydrite Ⅲ phase with type a and type | 3 two variants or two forms (Form).

That is to say, "variation" has a special meaning of the gypsum, it contains a form with two concepts, the difference between them, some depends on the crystal structure characteristics, others depends on the submicroscopic structure characteristics, such as grain size of the form, arrangement related to the specific surface area and the energy state, etc.

Depends on the crystal structure characteristics, some depends on the characteristics of microstructure, such as the grain morphology, arrangement related to the specific surface area and the energy state, etc.