Anhydrite Study

Anhydrite resource is one of our country's advantage of nonmetallic minerals, and the distribution is very wide, but it has not been exploited much all the time. The main reason is that the use of anhydrite in the field of building materials is more limited, mainly in its poor activity, difficult to dissolve in water, slow hydration rate, poor setting ability and even almost non-set, and basically does not have early strength, at present it is mainly used as cement coagulant, mineralizing agent. But in recent years, with the research and progress of deep processing technology of natural anhydrite, its application field is constantly expanding and changing. Compared with traditional building materials, anhydrite products have the characteristics of light weight, sound insulation, energy saving, environmental protection, ecological balance and other aspects have a unique advantage. Therefore, the application of natural anhydrite is gradually expanding, and its added value is also reflected in chemical industry, light industry, agriculture, precision casting, medical treatment, plastics and other fields. Yang Xinya et al. conducted heat treatment activation of anhydrite and found that anhydrite calcined at different temperatures had different solubility, among which the solubility of anhydrite reached the maximum after calcination. X-ray diffraction analysis shows that anhydrite will produce different degree of structural distortion after calcination at different temperatures, and the lattice structure changes of the left and right calcined anhydrite are the most obvious. Comprehensive analysis proves that the lattice structure of anhydrite can be distorted by calcination to improve its dissolution activity. It has also been reported that continuous grinding of different pulverizing equipment has significant influence on the particle size and distribution morphology of anhydrite, which leads to great differences in hydration activity and physical properties of anhydrite. The test results show that smaller than particle content, spherical particles and relatively narrow particle distribution have positive effects on the hydration hardening speed and strength of anhydrite. The main reason is that the material prepared by ball mill is approximately spherical and the particle surface is more coarse sugar than that of other materials, and there are a large number of microcracks. All these changes enhance the surface activity of anhydrite. Deng et al. enhanced the activity of natural anhydrite by using a mixture of valate cement, hemihydrate gypsum and potassium sulfate as an activator. The results showed that potassium sulfate content significantly improved the strength, cinnamate cement and on the strength and softening coefficient have a certain effect, among which a certain content range can improve the setting time of anhydrite and enhance the strength of anhydrite, but its content is not exceeded, too much content has adverse effects on the water resistance of anhydrite. At present, among the two activation methods, the more mature one is the physical activation method, which is mainly through grinding to improve the fineness of anhydrite, or by taking appropriate calcination temperature forging anhydrite; Chemical activation is relatively complex, mainly because its excitation mechanism is not perfect. The temperature of anhydrite and the excitation of different salts are well summarized, which has positive reference significance for the study of hydration activity of anhydrite