In order to improve the physical properties of raw zinc oxide such as direct zinc oxide and indirect zinc oxide obtained through zinc vapor refining, and the impact of its related chemical components, heavy calcined zinc oxide is obtained after high-temperature processing and calcination.

Calcined zinc oxide has a high specific gravity and good fluidity, and the glazes produced with it have low shrinkage, making it less likely for the glaze surface to develop pinholes and cracks. In addition to its specific gravity, the product quality standards of calcined zinc oxide are the same as those of graded zinc oxide.

The zinc oxide after high-temperature calcination appears light yellow, with a melting point of 1975°C.

Calcined zinc oxide is an important raw material for ceramic chemical flux, especially used in building ceramic wall and floor tile glazes, as well as low-temperature porcelain glazes and ceramic colorants. It is also widely used in artistic ceramic glazes. The role and use of ZnO in glazes: ZnO has a strong fluxing effect in glazes, which can reduce the expansion coefficient of the glaze, improve the thermal stability of the product, and increase the gloss and whiteness of the glaze, enhancing the elasticity of the glaze. While expanding the melting range, it can also enhance the brilliance of the glaze color. However, it should be used cautiously in black glazes containing chromium. In summary, ZnO is mainly used in the following aspects:

1. As a flux: When used as a flux in low-temperature frit glazes, the general dosage is between 5% and 10%, with a typical amount of about 5% in low-temperature raw material glazes.

2. As a clouding agent: Adding zinc oxide to glazes with a high content can improve the cloudiness of the glaze surface. This is because ZnO can form zinc spinel crystals. In zinc-containing clouding glazes, it can enhance the whiteness and cloudiness of the glaze surface. SiO2 can improve the gloss of the glaze surface.

3. As a crystallizing agent: In artistic glaze crystallization glazes, ZnO is an indispensable crystallizing agent, forming large crystal patterns during rapid cooling of the molten glaze, which are very beautiful. In crystallization glazes, the dosage of ZnO can reach 20% to 30%.

4. Used to make cobalt sky blue glaze: ZnO is a very important flux in cobalt sky blue glaze, as it can help cobalt oxide form a beautiful sky blue color in the glaze.

5. As a ceramic pigment: Due to its strong fluxing effect, ZnO can serve as a fluxing agent, mineralizer, and color carrier for ceramic pigments. It is used as a main raw material in the brown ceramic pigment series.

6. As a glass additive: Zinc oxide with added aluminum, gallium, and nitrogen can achieve a transparency of 90%, and can be used as a glass coating that allows visible light to pass through while reflecting infrared rays. The coating can be applied to the inside or outside of window glass to achieve insulation or heat insulation effects.