in silica sand instead of feldspar and this can be done by observing silica sand under binocular microscoap
Two main products of Quartz (Comparison):
High Purity Quartz (HPQ)
- There is no change in quartz chemistry. SiO2 remains as SiO2.
- Natural quartz produces HPQ via intensive physical, chemical and thermal processing.
- Impurities removed during processing and the purity level exceeds to >99.998% SiO2.
- The world demand of High Purity Quartz is around 60,000 tons / year.
- High Purity Quartz (HPQ) cannot be produced from silica sand. Producing HPQ from silica sand would not be economically viable due to the abundance of impurities in silica sand and the cost involved in processing.UNIMIN is the world leader in high purity quartz production.
- UNIMIN’s IOTA quartz HPQ standard) carries less than 20 ppm impurities.
Silicon Metal (Metallurgical Grade Si)
Natural quartz mixed with a source of C is heated at high temperatures (>2,800 degrees) and the reaction removes O and produces Si.
Quartz should meet the specification of silicon feed material. It cannot be processed as quartz should be in chunks of 3-15 cm. Processing requires grinding that will make quartz unsuitable for silicon manufacture.
Silicon metal cannot be produced from Silica sand due to the particle size requirement (3-15 cm.) which can be achieved only from quartz crushing.Uses of High Purity Quartz (HPQ) and Silicon Metal (Metallurgical Grade Silicon – MG-Si)
Uses of High Purity Quartz
- Optic Fibres-Crucibles (for making mono-silicon from polysilicon).
- Optical glass, lenses for telescope, microscope etc.
- Quartz glass for laboratory ware.-
High temperature lamp tubing.
- Epoxy moulded compound (EMC) fillers.
- Engineered quartz stone.Uses of Silicon Metal (MG-Si)
- 10% in polysilicon (solar-grade) production.
- 40% in aluminum alloys.
- 50% in silicones manufacture.
- The use of silicon in polysilicon and silicones manufacturing is via chemicals - trichloro silane and dichlorodimethyl silane respectively.