The main raw materials of photovoltaic glass are: silica sand, soda ash, dolomite, limestone, aluminum hydroxide, mirabilite, sodium nitrate, sodium pyroantimonate, and some recycled broken glass.Due to the special requirements for light transmittance of photovoltaic glass, it is generally required that the iron content of each raw material is low, and the raw material is low iron, in order to obtain high light transmittance.
1. Silica sand, the main component of silica, general factory selection principle
11 High SiO2 content and stability.
1.2 Low Fe2O3 and Al2O3 content and stable.
1.3 There are no refractory particles, such as chromite and other pollutants.
1.4 Appropriate particle size, no large particles and too much fine powder.
1.5 Stable moisture content.
Specific index requirements
A. Chemical composition:
| Content | SiO2 | Al2O3 | Fe2O3 | LOI | Moisture |
| % | ≥99.3±(0.4) | ≤0.3±(0.1) | ≤0.008 | ≤0.15 | ≤5.0 |
If there is a homogenizing storage facility, the water control and control can be appropriately relaxed to meet the requirements of feeding into the homogenizing storage.
B.Particle distribution
| mm | 1.0 | 0.71 | 0.50 | 0.125 | -0.125 |
| % | Nil | ≤Nil | ≤5.0 | ≥90.0 | ≤10.0 |
In terms of particle size distribution, some literatures show that the fine powder standard can be appropriately relaxed to 15%, but the type of kiln should be considered. If it is an all-oxygen kiln, it can be appropriately relaxed, while if it is an air kiln, it should not be relaxed, so as to avoid the defects of fine powder clogging the lattice and flying away causing white defects.The melting point of silica sand is > 1800℃. If there are larger particles, the situation of no melt may occur (depending on the traction amount and the melting rate of the kiln).
At present, the main sources of silica sand are: Fengyang area, Anhui Province, Wenchang, Hainan Province, Hepu, Beihai, Zhanjiang, and Heyuan area.Abroad, there are currently Indonesian, Malaysian, Vietnamese and Australian sand.In fengyang and heyuan vein quartz ore quality as the last times for kaolin elutriation made sand gravel crushing again (e.g., hepu, zhanjiang sand), again is the sea sand (mainly contain titanium dioxide not remove or reduce, the kiln has certain erosion, and titanium dioxide residues in glass can lead to uv light transmittance glass down).
2. Soda soda, glass factories generally choose heavy soda soda, the main component of sodium carbonate, play a role in fusing, its granularity and silica sand into a relationship, general factory requirements of soda soda quality standards and selection principles are as follows:
2.1 High Na2CO3 content
2.2 Low content of NaCl and Fe2O3
2.3 Appropriate particle size and free from contaminants and caking.
Specific index requirements
A. Ingredient requirements:
| Content | Na2CO3 | NaCl | Loss | Fe2O3 |
| % | ≥99.0 | ≤0.50 | ≤0.50 | 0.0030 |
5. Aluminum hydroxide, mainly provide alumina components, the strength of the glass to enhance the role, but the high alumina content may lead to melting clarification of poor situation, need to be cautious increase, the general industry requirements of photovoltaic glass alumina content in 0.95-1.05% or so, can obtain good cutting performance and strength requirements.Because aluminum hydroxide is easier to melt than alumina, and can produce water molecules to discharge, enhance clarification, so most of the factory is the choice of aluminum hydroxide as the raw material to introduce alumina composition.However, recent studies have shown that ultrafine alumina powder can still be used on photovoltaic glass without affecting the quality of the glass. The raw material is made use of the characteristics of small particle size and larger than the surface energy.Selection principle of aluminum hydroxide plant:
5.1 Aluminum oxide content should be high, aluminum hydroxide should be high
5.2 Low Fe2O3 content requirement
5.3 No pollution and no caking.
Post time: Apr-26-2021