【 Building materials network 】 Ultrawhite glass It is a kind of ultra transparent low iron Glass , also known as low iron glass and high transparent glass, with glass family“ crystal Prince ". It has the advantages of low self explosion rate, color consistency, high visible light transmittance, good permeability and low ultraviolet transmittance. It is a new type of high-grade glass with high quality and multi-function. Mainly used in solar energy Battery , solar thermoelectric reflector, high-end building decoration electronic products, high-end car glass and other industries.

As the basic product of the solar energy industry, ultra white glass is required to have a direct sunlight transmittance of more than% (equivalent to 3mm standard thickness), while ordinary glass Float glass The light transmittance is generally 86%. To achieve this goal, the content of coloring oxidant Fe2O3 must be controlled to 150 pp M below. It can be said that the production process of ultra white glass is the process of controlling Fe2O3 content.

Reasonable selection of raw materials

Because the iron oxide not only makes the glass colored and affects the light transmittance of the glass, but also because the iron oxide has a strong absorption effect on the thermal radiation, most of the radiant heat is absorbed by the surface liquid glass, so that the upper and lower layers of the liquid glass produce obvious temperature gradients, leading to the difficulty of convection of the liquid glass in the furnace, which increases the difficulty of melting and clarification. In order to effectively reduce the iron content of glass, we should first start from raw materials, and effectively select raw materials with low Fe2O3 content is the prerequisite for the production of ultra white glass.

Raw materials for ultra white glass include dolomite 、 limestone 、 feldspar , silica sand. For example, magnesium oxide can effectively control the hardening rate and crystallization performance of the liquid glass, mainly the high temperature physical properties of the glass, and improve the melting performance of the glass as a melting aid. Dolomite is the main raw material for introducing magnesium oxide. Limestone is another important mineral raw material. At present, the content of limestone Fe2O3 supplied for ultra white glass is below 50ppm.

Among the many raw materials, SiO2 is the main body to form the glass skeleton. The introduced SiO2 siliceous raw material is the main raw material with large amount in glass production, and it is also the first thing to solve and control in the production of ultra white glass.

There are two main sources. One is high-quality quartzite Its own grade meets the requirements of low iron glass production. In the process of processing, the mixing of iron should be minimized. The traditional stone roller can be used, which is only available in a few areas such as Fengyang, Anhui. The other is for ordinary plate glass The high-quality silica sand is used for flotation and other mineral processing to meet the requirements. The cost of this sand is relatively high, more than twice that of the natural high-quality quartzite mentioned above. At present, these two methods can control the content of Fe2O3 below 100ppm. In this way, the iron introduced by silica sand can be controlled below 73 ppm.

Development opportunities brought by industrial policy orientation

Building energy conservation is a comprehensive system engineering, and scientific and reasonable use of processed glass with energy-saving, safety and environmental protection characteristics is one of the most important links in this system engineering.

In recent years, relevant favorable policies have been introduced. For example, the Guiding Opinions on Promoting Steady Growth, Adjusting Structure and Increasing Benefit of Building Materials Industry (GBF [2016] No. 34) clearly pointed out that the integration of silica sand for glass Quartz sand and sand Tailings, waste rocks and other resources used for aggregates to improve the comprehensive utilization level; The development plan of building materials industry (2016-2020) clearly points out that we should vigorously develop ultra white glass and quartz glass Products, refractory materials, building and sanitary ceramics and other industries; GXBG [2016] No. 344 Document "Development Plan of Industrial Technological Innovation Capacity (2016-2020)" clearly points out that it is necessary to focus on the development of flat glass, building sanitary ceramics, refractory materials and other building materials industries. The introduction of favorable policies undoubtedly created a good policy environment for the development of glass industry and quartz sand industry, and provided opportunities for their development.