| Recently, due to the fast development of electronics and photovoltaic industry, the demand for high-purity quartz has been increasing day by day. As quality crystal resources are depleting, there is great significance and application value to explore a method that using quartz rock to produce high-puriy quartz.The quartz, which is from southwest China, was roasted in vacuum and nitrogen atmosphere to study the migration and diffution of metallic elements in quartz.The mineralogy research of refined quartz was done by using analysis methods such as XRD?ICP?Optical microscope and electron microprobe to identify the occurance state amd contents of the matellic elements in quartz. The quartz was pured by using different atmosphere as protect environment to induce the matellic elements diffuse from inside to the surface. Analysis and discussion were done by using test and analysis technology such as ICP?XRD?SEM and XPS, and the results are as follows:1. The mineralogy research shows that the quartz, in which SiO2 contens is 99.968%, is very pure. And the main impurities are Na?K?Fe?Al?and Ca, which make up 87.14% of the total inpurities. Impurity elements are mainly concentrated in the micron-sized mineral inclusions and fluid inclusions, which are consists of aluminum silicate minerals such as mica, feldspar, diopside and metallic minerals which contain Fe and Ti. Futhermore, there is also a number of iron in the surface of quartz.2. The results of roasting experiments showed that the seperation effect of Na?K and Fe in quartz was desirable by roasting in different atmosphere, however, the seperation effect of Al and Ca in quartz was not ideal in the same roasting condition.? The contents of Na in the quartz decreased from 50.91?g g-1 to 15.14?g g-1, and the removal rate of Na was 72.22% when the quart was roasted at 1500? in vacuum condition for 3 hours.? The contents of K in the quartz decreased from 23.43?g g-1 to 5.73?g g-1, and the removal rate of K was 75.54% when the quart was roasted at 1500? in nitrogen atmosphere for 3 hours.? The contents of Fe in the quartz decreased from 17.78?g g-1 to 2.45?g g-1, and the removal rate of Fe was 86.22% when the quart was roasted at 1500? in nitrogen.? The contents of total metallic elements diminished from 179.65?g g-1 to 108.68?g g-1 when the quart was roasted at 1500? in nitrogen atmosphere for 4 hours. And the removal rate was 39.50% because the diffusion of different metallic elements demonstrated a great difference in the same condition due to diversity in physic and chemical properties.3. Phase transition was significantly affected by roasting atmosphere when the roasting temperature was 1500?. The theoretical phase transition temperature of quartz into cristobalite was about 1447?, and this phase transition was bound to create a change of lattice parameters of quartz. XRD patterns indicated conversion ratio of cristobalite in nitrogen atmosphere was apparently higher than that in vacuum. Lattice parameter results showed that when roasting temperature was between 600? and 900?, the affect of temperature and atmosphere was not obvious. However, a remarkably modify was detected at 1500?, which demonstrated that thermal energy was enough to motivated crystalline transition from quartz into cristobalite and directional realignment of atoms in quartz crystal lattice.Gases environment played a significant role for migration of Al and its coordinating atom K?Na?Li., et al.4.XPS spectrum proved that metallic element impurities K?Na?Al?Ca., et al scattered on the surface of quartz remarkably decreased when the quartz was roasted in nitrogen atmosphere at 1500 for 4 h, which indicated ? that the quartz had been purified due to the impurities' migrating onto the surface and diffusing into the atmosphere. |
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