Prominer has the ability to supply the complete industrial deep processing solution to supply the quartz sand and high purity quartz (HPQ) sand. The quartz sand is widely used in glass, ceramic, casting, construction industry and filler for rubber, paper and paint industry. The HPQ sand is strategic mineral using for high-tech industry such as semi-conductor, optical, lighting, quartz glass, crucible and solar energy industry.
In recent years quartz slab industry develops very fast as it is used widely in room decoration especially in kitchen, thus a great demand of white & transparent quartz sand is open for the market. Due to the simple production process, just crushing, optical sorting and sieving, the investment return cycle is short and the benefit well. Prominer is familiar with the complete industrial chain of the quartz slab, from the material sand production technology till the final quartz slab manufacturing plant and thus can provide support on every stage.
To get qualified quartz sand/powder, the first aim is to remove the impurities inside the quartz. Specific expertise in geology, chemical analysis and high purity processing are required in order to convert raw mineral quartz into high purity & high-value final product. Based on the geological setting, lab test and pilot test, Prominer supplies tailor-made technology to remove the fluid and/or mineral inclusions. Depending on the final quality and value, processing into high purity or high value quartz involves advanced technology such as:
Mixed acid treatment
Hot Chlorination Calcination
Free contamination sintering
Most of the quartz sand application field has strict requirements on its size range, so during the crushing and grinding process, suitable crushing & grinding solution is required to liberate quartz crystals from gangue sufficiently without contamination, meanwhile minimizing the under-size particle production.
The purity of quartz sand determines its value and application fields, and most processing is for removing the mineral impurities. So, the way to prevent new contamination during crushing and grinding process is also very important. Ceramic grinding system, stainless steel connecting parts, clean working environment and dedusting system are very helpful to minimize the emergence of new impurities.
Optical sorting is a new and advanced technology to separate the mineral ore based on the difference of the material optical properties. It uses the photoelectric detection technology to automatically separate the particles of different optical characteristics from the granule materials. The optical sorting machine consists mainly feeding system, optical detection system, signal processing system and separation execution system. Compared with traditional manual sorting, it is with much higher efficiency.
Quartz lumps production causes fragmentation of the quartz rock along its crystal and impurities boundaries. Since crystal boundary contains most of the mineral impurities, the liberation of its crystal and impurities boundaries is very important in downstream processing. The calcination plus water quenching process is very effective to reach the aim of removing impurities.
Apart from the common thirteen types of impurities such as K, Na, Li, Mg, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Al, the gas & fluid inclusion is also the main impurity needs to be removed. During the sintering process, the crack will present at gas & fluid content area that also contain some mineral impurities. Sintering plus water quenching process is a kind of selective fragmentation technology to select liberation of gas and fluid inclusion.
In order to prevent the new contamination issues, high purity quartz glass is chosen as the sintering chamber.
Attrition is applied to clean the surface of the quartz particles. Thereby fine particles attached to quartz surfaces, e.g. clay minerals or iron oxide coatings, are liberated, which allows the subsequent physical separation including magnetic separation and flotation process.
Magnetic separation removes heavy minerals from quartz as they are mostly paramagnetic or even ferromagnetic. These minerals are attracted towards increasing magnetic field strength. Most of the gangue minerals are weak magnetic minerals, so the high-intensity magnetic separator is required. Generally, there are two types high-intensity magnetic separator including permanent magnetic type and electromagnetic type.
Froth flotation selectively separates minerals according to the difference of those to be wetted, enhanced or suppressed by conditioning reagents. To prevent the new impurities obtained, the flotation cells with rubber or plastic liner is necessary.
Chemical processing: Chemical treatment is an important addition to physical processing methods in order to achieve maximum purity quartz through the removal of surface impurities. Leaching and hot chlorination are the two chemical treatment processes.
During mixed acid treatment, medium to strong mineral acids are used at elevated temperatures. A combination of several acids can be used (HF, HCl, HNO3) to improve chemical purification results. Mineral impurity like feldspar, mica, which is very difficult to liberate during physical processing, are dissolved in the process of mixed acid washing. Additional impurities, enriched in micro fissures and structural dislocations, can be removed by the enhanced dissolution of quartz.
After boiled in reactor with sufficient time, quartz will be rinsed by deionized water washing away the dissolved impurities.
In the hot chlorination process, quartz is heated to temperatures of 1,000 – 1,200 °C in a chlorine or hydrogen chloride gas atmosphere. This refining process is suitable to specifically reduce the level of alkali metal, alkaline-earth metal, and transition metal impurities which are highly restricted in semiconductor applications.