Research On Removal Of Fluid Inclusions From Quartz Sand Through Acid Leaching-Aided Microwave Field

The demand of high-purified quartz glasses is increasing with the rapid growth of high-tech industries. However, the natural crystals are nearly exhausted and the area distribution is extremely uneven. Thus, it is imperative to explore the method to prepare high-purity quartz glass by ordinary quartz crystal instead of natural crystals. Generally, ordinary quartz ores contain fluid inclusions that are difficult to remove by current technology. Since these impurities in constructive result in the flaws of the quartz glasses such as bubbles, it is of vital importance and difficult to remove the fluid inclusions from ordinary quartz to prepare the high-purified quartz glasses materials.In this paper, the effect of temperature on the removal of fluid inclusions from quartz sand in microwave field is studied based on the selection of high-quality quartz sand that suitable for microwave process according to the characteristics that microwave can be used as "body heat" and selective heating. The mean contents are as follows.(1)To begin with, the quartz ore mine from four different regions were analysed, the results showed that, the quartz ore from Madagascar contains the least and impurity ions, moreove, the liquid filling degree of fluid inclusions are relatively high. Therefore, Madagascar quartz mine is the most suitable raw material in this paper. By the experiment on microwave heating quartz sand, we found that when quartz sand was heated to 600 ℃and 900℃in the microwave field, the sample fluid inclusions content decreased sharply. Infrared spectroscopy results showed that, the quartz sand treated microwave field, its water molecules content decreased significantly compared to raw materials. Polarized light microscopy and SEM analyse revealed that after the process that the microwave field was heated to 900 ℃for 120 minutes, quartz sand particle surface produced more micro cracks and they are wider, which is more conducive to the escape of fluid inclusions burst.(2)By using theories such as the microwave physics and chemistry theory and fluid inclusions thermodynamics theory, we can establish a fluid inclusions(A pure water system) in the microwave field heat burst model, a deeper knowledge and understanding of the microwave "Open" gas-liquid inclusions thermodynamic properties, and explain the root causes of a small amount of fluid inclusions difficult for small burst in the microwave field.(3)Adopting the method of pickling after microwaving process to dispose quartz sands, it is better for us to explore the influence of acid type, acid pickling temperature and time on fluid inclusions and main unpurified ions’ content. Moreover, we found the best pickling process according to this method: mixed acid ratios 20%HCl, 20%H2C2O4, 15%HF and 45%H2O, pickling time for 6 hours and pickling temperatureof 80℃.