Geology and mineralization conditions of high-purity quartz raw materials
1. Geological genesis type: Quartz ores of different genesis types have obvious differences in their mineralogical characteristics. For example, quartz ores of granite pegmatite, high-temperature metamorphic rock-type quartz, metamorphic quartz-type quartz, etc. may have better performance in terms of purity and inclusion content, and are more likely to be suitable for processing into high-purity quartz. However, some quartz ores with complex formation conditions and multiple periods of geological action may have a large amount of impurity content and inclusions, and are not suitable for processing high-purity quartz.
2. Mineralization temperature and pressure: The temperature and pressure at the time of quartz deposit formation have an important influence on the quality of quartz. Generally speaking, quartz formed under high temperature and high pressure may have impurities in its grains that are more likely to migrate to the edge of the grain boundary or into fine inclusions, and the content of fluid inclusions in the formed quartz may be less, which has the potential to be processed into high-purity quartz.
Source and embedding characteristics of high-purity quartz raw materials
1. Mineral type
The resource type of high-purity quartz raw materials is not limited to natural mineral rocks composed of a single quartz. Its sources include crystals with strict geological production conditions, vein quartz, quartzite, quartz sandstone, etc., and can even be obtained from rocks rich in quartz minerals such as granite pegmatite. There are differences in the properties of quartz raw materials of different genesis types, and the application fields are also different, but high-purity quartz raw materials only account for a small part of them, mainly used to produce high value-added products.
Physical and chemical properties
High temperature resistance, corrosion resistance, low thermal expansion, high insulation and light transmittance: high-purity quartz has these excellent physical and chemical properties, so the physical and chemical properties of the original ore also need to be tested and analyzed.
The resource utilization characteristics of high-purity quartz raw materials are based on the physical and chemical properties of quartz itself. The raw materials need to be processed by mineral processing technology to separate the gangue minerals in the quartz sand, enrich the pure quartz particles, and if necessary, destroy and remove the inclusions and isomorphous impurity elements inside the quartz, and finally purify them to the industrial requirements of the target application field.
The purification potential of high-purity quartz raw materials is affected by the chemical composition, mineral composition, embedded particle size and consolidation degree of the ore. The higher the chemical purity of the purified product, the higher the value. The downstream quartz products have the characteristics of high high-tech content and cutting-edge application fields. The processing process of high-purity quartz raw materials has the characteristics of great influence of the original ore properties, high product purity, strong application purpose and easy to be polluted.
Mineralogical characteristics of high-purity quartz raw materials
1. Impurity element content
There are many types of impurity elements in quartz raw materials, high content, and diversified occurrence states. The thermal conditions for the formation of quartz ores in different regions are different, and the occurrence states of impurities in the raw materials are different. It is necessary to analyze the chemical composition of the ore to ensure that its main component is SiO2 and the content of impurity elements is low.
To select the correct high-purity quartz raw materials and formulate the best quartz purification plan, it is necessary to clarify the occurrence state of impurity elements in quartz. Many quartz ores are not single quartz minerals, but also accompanied by other minerals. For example, minerals such as mica and feldspar often coexist with quartz. Co-existing independent gangue minerals (such as mica, feldspar, hematite, tourmaline, chlorite and clay minerals) are the main carrier minerals of impurity elements in quartz, and they are very easy to become mineral inclusions in quartz during geological mineralization, which is one of the important factors restricting the quality of the final quartz product.
2. Mineral composition and intercalation characteristics
Vein mineral types and content: Vein minerals refer to other minerals associated with quartz ore. The fewer the types of vein minerals and the lower the content, the more conducive to the purification of quartz. For example, quartz in rocks such as granite and pegmatite is an ideal source of quartz raw materials because it has relatively few impurity minerals and is easy to separate and purify; while intermediate-acid igneous rocks such as granite and diorite, although containing a large amount of quartz, other rock-forming minerals such as feldspar, amphibole, and mica are often intercalated with quartz, and are not good quartz source rocks.
Intercalation particle size and dissociation degree: The intercalation characteristics of quartz and vein minerals directly affect the dissociation degree of quartz monomers, and thus affect the effect of mineral processing and purification.
3. Fluid inclusions
Fluid inclusions: Fluid inclusions are the most common and abundant inclusion type in quartz. According to the state of the contained substances, they can be divided into pure gas, pure liquid, gas-liquid mixed inclusions, and three-phase inclusions. Fluid inclusions contain impurities such as sodium (Na), potassium (K), and calcium (Ca), which are one of the main sources of impurities in high-purity quartz products and have a serious adverse effect on the melting behavior of high-purity quartz. Therefore, it is key to select quartz with very little or no fluid inclusions as high-purity quartz raw materials.
Mineral inclusions: Co-existing independent gangue minerals (such as mica, feldspar, hematite, tourmaline, chlorite and clay minerals, etc.) are easy to become mineral inclusions in quartz, which is one of the important factors restricting the quality of the final quartz product.
4. Lattice impurities
During the formation of quartz crystals, some elements will replace silicon elements into quartz crystals to form lattice impurities. Although the content of these impurities is very low, it is difficult to separate them from quartz, which is one of the most critical factors restricting the quality of high-purity quartz. For example, aluminum elements are more common in the form of aluminum ions (Al³⁺) replacing silicon atoms. Since it will cause charge imbalance inside the quartz lattice, when there are a lot of aluminum impurities in quartz, the content of impurity elements such as lithium (Li), potassium (K), and sodium (Na) may also increase. Therefore, the quality of quartz raw materials can be judged by analyzing the aluminum content in quartz.
Crystal structure impurities in quartz are divided into lattice impurities and non-lattice impurities. Lattice impurities mainly replace silicon atoms in silicon-oxygen tetrahedrons in an isomorphic manner with other atoms. The main impurity elements are Al3+, Ti4+, Ge4+, etc.