Method for preparing expanded vermiculite by utilizing ultrasonic pretreatment way

Abstract

The invention discloses a method for preparing expanded vermiculite by utilizing an ultrasonic pretreatment way, comprising the following steps of: (1) taking industrial vermiculite, screening and grading, removing impurities and selecting vermiculite raw materials with the flake size of 0.3-5mm; (2) injecting hydrogen peroxide with the concentration of 5-30 percent into a vessel, immersing the vermiculite raw materials into the hydrogen peroxide and soaking for 1-14h; (3) placing the soaked vermiculite raw materials into an ultrasonic device and ultrasonically pretreating the vermiculite raw materials for 10-60min to promote hydrogen peroxide molecules dispersed in the vermiculite raw materials into spaces among crystal layers; and (4) taking the ultrasonically pretreated vermiculite raw materials out, standing for 1-2h, then placing the vermiculite raw materials into a microwave device and carrying out microwave expansion for 0.5-4min to prepare the expanded vermiculite. The method is beneficial to shortening the production cycle and enabling the vermiculite to be fully expanded; and the obtained product has the advantages of low density, low heat conductivity coefficient, flexibility and difficulty in crushing and pulverizing, effectively promotes the quality of the expanded vermiculite, enlarges the application range of the expanded vermiculite and is beneficial to popularization and application.

Description

technical field [0001] The invention relates to a method for preparing expanded vermiculite, in particular to a method for preparing expanded vermiculite by ultrasonic pretreatment. Background technique [0002] At present, the methods for preparing expanded vermiculite at home and abroad mainly include thermal expansion method, the heating temperature is 800~900°C, and the expansion time is about 1 minute. As the vermiculite expands, it gradually becomes brittle and cracks. The produced expanded vermiculite produces a lot of expanded vermiculite powder due to its high brittleness and easy pulverization, which greatly affects the quality of expanded vermiculite as a lightweight heat insulation material. It has seriously affected the application of expanded vermiculite in the fields of heat preservation, sound insulation and fire prevention. [0003] In recent years, with the increasing demand for high-performance expanded vermiculite, expanded vermiculite with low density a...

AI Technical Summary

Problems solved by technology

[0012] To sum up the above research results, it can be seen that the use of heating expansion method, microwave chemical method, hydrogen peroxide immersion and other methods has made great progress in the change of the volume expansion rate of expanded vermiculite, the peeling of vermiculite layers and the solution to the problem of embrittlement of expanded vermiculite. progress; but there are still the following defects, such as the vermiculite soaked in hydrogen peroxide, in which the hydrogen peroxide can only diffuse through the concentration gradient and enter the vermiculite layer, and the entry speed is relatively slow, and the hydrogen peroxide will not only gradually increase with time. Decomposes and releases oxygen, which affects the dispersion of vermiculite by hydrogen peroxide and the peeling effect of sheets; and the production cycle is long

Another example is the use of heating expansion method, which can easily lead to the embrittlement of expanded vermiculite, which limits its application range.