Research On Removing Tiny Fluid Inclusions For Preparation Of High Purity Quartz Sand

High-purity quartz sand is the main raw material of quartz glass, quartz crucible and other high-end products. High-purity quartz has also been applied in large scale integrated circuit, optical fiber, solar cells, laser, aerospace, military.With the depletion of natural crystal and the expansion of photovoltaic, silicon microelectronics industry, the greater high purity quartz are required, so the substitution of natural crystal from ordinary quartz materials, the treatment to the raw quartz materials, the appropriate purification process for producing high purity quartz are also required.Ordinary quartz generally contain fluid inclusions, water is the most common fluid present. The bubbles and remaining hydroxyl in quartz glass correlate with the characteristics of inclusions in raw minerals. The bubbles in quartz glass were caused mainly by fluid inclusions which cannot burst at high temperature and the remaining hydroxyl in quartz glass were formed by fluid inclusions molecular water dissolved in melting silica, while the remove of fluid inclusions in quartz is one of the difficulties.Inner Mongolia Mayazishan quartz ore were selected as the object of this research in this paper, and we focus our attention on removing fluid inclusions from quartz especially tiny fluid inclusions (1-6μm). Depend on the characteristics of the fluid inclusions, the mechanism to remove fluid inclusions has been discussed, and the appropriate heat treatment process was figured out, and also the leaching process has been researched.Through the high temperature heat treatment experiment, multiplicating shock heating at1500℃was the optimal treatment process, after the high temperature treatment, a lot of microcracks were well-distributed come into being on the surface and inside of quartz, which serve as the pathway for the component to escape from fluid inclusions.The quartz sand that shock heated was selected as the raw material for leaching experiment, the species of acid, temperature for leaching, time for leaching has been researched, and optimized parameter for acid leaching are mixed acid with HF、HCl、 HNO3at80℃for10hours, the concentration of all the impurity after acid leaching were less than50ppm.