Quartz resources are an important non-metallic mineral resources, which can be used as raw materials for processing glass sand, industrial silicon, etc., and are important raw materials for metallurgy, chemical industry, glass, ceramics, casting, rubber and other industries, as well as the cornerstone of the development of electronic information industry, photovoltaic, new energy industry and organic silicon new material industry.
There are many kinds of genesis of quartz deposits in nature, and the industrial types of quartz deposits that are commonly available for development and utilization include natural crystal, quartz sandstone, quartzite, vein quartz, powder quartz, natural quartz sand and granite quartz.
1. Natural crystal.
Natural crystal is a transparent large quartz crystal mineral, the main component of which is silica. Crystals are mostly formed by natural growth in caves, rock cracks or joints, and faults, and their growth conditions are harsh, and four conditions must be met at the same time: sufficient growth space, can provide hydrothermal fluids rich in silica, a certain temperature and pressure, and enough growth time. China's natural crystal resources are widely distributed, among which the East China Sea area of Jiangsu is the most abundant.
Natural crystal deposits have small reserves, poor mining conditions, scarce resources, and are expensive, which is difficult to meet the needs of large-scale industrial production. However, due to the rich color, crystal clear, beautiful and pure natural crystal, it is currently mainly used to carve various handicrafts.
According to the characteristics and uses of crystal, it can be divided into piezoelectric crystal, optical crystal, smelting crystal and craft crystal.
Piezoelectric crystal: widely used in automatic **, supersonic aircraft, missiles, nuclear**, high-power electron microscopes, timers, electronic computers, artificial satellites and other scientific and technological navigation, remote control telemetry, electronic telecommunications equipment;
Optical crystal: mainly used in the manufacture of quartz refractometer, infrared analysis window, spectrometer and spectrometer, etc
Smelting crystal: mainly used to make all kinds of quartz glass and produce artificial crystal;
Craft crystals: used in the manufacture of spectacle lenses and various handicrafts.
2. Quartz sandstone.
Quartz sandstone is a sandy sedimentary rock consolidated by sedimentary action, and its quartz and siliceous clastic content is generally 95%, and the secondary minerals are mostly feldspar, mica and clay minerals, and the cementation is generally siliceous. At present, quartz sandstone in China is distributed in all provinces, among which Daguan, Yanjin, Yiliang and Muchuan in Sichuan are rich in resources.
Quartz sandstone deposits are generally large in scale, with stable geological occurrence and good mining conditions. At the same time, the hardness of ore is generally relatively low, the natural particle size is moderate, and it is easy to crush and classify and large-scale industrial production. However, due to the complex composition of quartz sandstone cement, it is usually used in the production of daily glass sand, glass fiber, silicon metal, refractory materials, silica, silicone and other fields.
3. Quartzite.
Quartzite is usually a metamorphic rock formed by regional metamorphism or thermal contact metamorphism of quartz sandstone or other siliceous rocks, and the associated minerals often contain trace amounts of tourmaline, hematite and zircon in addition to feldspar, mica and clay minerals. Compared to quartz sandstone, quartzite is more dense and hard in its ore. China's quartzite resources are very abundant, and the amount of development and utilization is large, mainly distributed in Fengyang, Anhui and other regions.
Quartzite deposits have the advantages of large scale, stable geological occurrence and good mining conditions, and its ore is generally dense and uniform, with good blockiness, which is more suitable for large-scale industrial production of products with SiO2 content of about 99% in traditional application fields such as daily glass sand, float glass sand, glass fiber, silicon metal, refractory materials, quartz plates, etc.
4. Vein quartz.
It is mainly formed under the action of magmatic hydrothermal fluid, usually in a dense massive structure, and its mineral composition is single, almost all of which are quartz, and the SiO2 content is generally more than 99%. Vein quartz deposits are generally not large in scale, steep in occurrence, thickness is generally a few meters to tens of meters, and the length is generally more than ten meters to several hundred meters, and a mining area can be composed of one vein or multiple veins.
The scale of vein quartz deposit resource reserves is generally relatively small, and the mining difficulty is relatively large, but due to its low impurity content and stable resource quality, it is mostly used to prepare SiO299% 999% silica powder, low-iron quartz sand, optical glass, semiconductors and other high-quality quartz products.
5. Pink quartz.
It is usually a sedimentary weathering deposit formed by the weathering and decomposition of siliceous parent rock under special geological structural conditions (warm and humid paleoclimate, gentle terrain paleogeography, hydraulic action, etc.), and the quartz content is usually 95% 98%, and some can be as high as 99%.
There are many such deposits in southern China, such as Guizhou Guiding, Jiangxi Lianhua, Yudong Yunfeng Mountain, etc. Compared with quartzite and quartz sandstone, the scale of this type of deposit is relatively small, and its main advantages are high natural whiteness, natural loose and porous, easy ultra-fine crushing and processing, and can be used as ceramic raw materials, silica powder fillers, etc.
6. Natural quartz sand.
Natural quartz sand is a kind of sandy quartz mineral raw material with quartz as the main mineral component formed by the long-term weathering of granite, quartzite, quartz sandstone and vein quartz and other parent rocks through nature, and its associated minerals include feldspar, cuttings, mica, clay minerals and heavy minerals such as zircon, tourmaline, ilmenite and hornblende, mainly marine sedimentary placer deposits and fluvial-lacustrine sedimentary placer deposits.
The scale of this kind of deposit is generally large, and its main advantage is that it usually has a natural moderate particle size and angular shape factor, and it is simple to mine, which is an ideal raw material for processing and casting quartz sand products, but the disadvantage of this type of deposit is that there are more impurities.
7. Granite stucco.
Refers to the quartz in large-grained granite or granitic pegmatite (white granite) formed by the consolidation of rocks due to magmatic action. The quartz grade in this type of deposit is mostly about 25%, and the mineral impurities mainly come from the fluid inclusion-grade lattice impurity elements in the quartz particles.
The discovery of this particular type of quartz deposit is legendary: at the beginning of the 20th century, the main mineral resources in the region were pegmatite feldspar and mica minerals, which could be directly processed by hand because of their coarse grains. At first, the quartz in granite was not well utilized, as a tailing material for feldspar flotation and kaolin**, producing thousands of tons of crystalline quartz sand per month. Some of the quartz sand is processed and sold to nearby ceramic factories for use as raw materials for ordinary ceramics, while most of it is discarded like garnet, biotite and other impurity minerals found in feldspar and kaolinite.
In the 70s of the 20th century, due to the depletion of natural crystal, the raw material of quartz glass, the search for natural quartz that can replace crystal has become an urgent goal for many countries at that time. In this context, a high-purity quartz sand was produced by an improved flotation technique that replaces natural crystals from quartz in the pegmatite granite of the Spruce Pine area.
The 2nd Anhui International Quartz Industry Conference & Exhibition 2024 was held in Hefei from May 8 to 10.