Sodium Pyroantimonate: A High-Performance Alternative to Antimony Trioxide

What’s Sodium Pyroantimonate

Sodium pyroantimonate was primarily used in the glass industry and for cast iron enameling. In recent years, with advancements in science and technology, sodium pyroantimonate has partially replaced antimony trioxide in certain flame retardants and electronic products.

Sodium pyroantimonate is a white powder available in granular and isometric crystalline forms. It exhibits high thermal stability and does not decompose at temperatures up to 1000°C. It is employed as a high-grade clarifying and decolorizing agent in glass production, as a flame retardant in plastics and textiles, as an opacifier in enamels and ceramics, and as an opaque coating in casting paints. Sodium pyroantimonate appears as a white or off-white crystalline powder, which is readily soluble in hot water, sparingly soluble in cold water, and insoluble in ethanol.

Applications

• Used as an opaque filler, opacifier in enamels, and acid-resistant paint for tinplate and steel sheets.
• Employed as a clarifying and decolorizing agent in high-grade glass such as cathode-ray tubes and optical glass. It offers resistance to solarization and excellent lampworking performance.
• Serves as a flame retardant in textiles, plastics, and rubber industries.
• Used in engineering plastics for its low tinting strength, reducing pigment consumption; applied in enamel, acid-resistant ceramics, and high-grade ceramics.
• Utilized in chemical analysis for the identification of sodium ions.

Characteristics

The replacement of antimony trioxide with sodium pyroantimonate in some applications is driven by the following factors:

• The use of sodium antimonate is economically advantageous, typically saving about 20% in raw material costs.
• When used as a clarifying agent in special glass industries such as electron tubes, sodium antimonate enhances the transparency of the glass.
• When antimony trioxide is used as a glass clarifying agent, trivalent antimony must be converted to pentavalent antimony. In sodium antimonate, antimony is already in the pentavalent state, which is highly beneficial for production.
• The use of antimony trioxide as a glass clarifying agent requires the addition of sodium nitrate, whereas sodium antimonate does not require additional sodium nitrate.
• Sodium antimonate has a much lower tinting strength than antimony trioxide, along with lower arsenic and lead content, making it superior for use as a low-tinting flame retardant in plastics.

The antimony content in sodium antimonate is significantly lower than that in antimony trioxide. However, the quantity required and the effectiveness in applications such as flame retardants and cast iron enameling are comparable, indicating that the use of sodium antimonate reduces antimony consumption.