The role and principle of water glass in mineral processing

Water glass is an inorganic colloid and is the most commonly used inhibitor in flotation operations. Water glass has a good inhibitory effect on quartz, silicate minerals and aluminosilicate minerals (such as mica, feldspar, garnet, etc.), and is used in large quantities as a gangue inhibitor.

Water glass is a sintered block of water glass formed by heating and melting quartz sand and sodium carbonate. The sintered block dissolves in water to form a paste-like colloid. It has a complex composition and contains sodium metasilicate Na 2 SiO 3. sodium orthosilicate Na 2 SiO 4. sodium disilicate Na 2 SiO 5 and SiO 2 colloid particles. It is usually expressed as Na 2 SiO 3.

The materials used to make water glass are quartz and sodium carbonate. Due to the different proportions of the materials used, the properties of the water glass formed are somewhat different. Generally, the ratio of Na 2 O to SiO 2 is used to express the composition of water glass. The ratio of mNa 2 O·nSiO 2 n/m is called the modulus of water glass. The water glass used for flotation has a modulus of n/m = 2.0~3.0. and the commonly used water glass quality standard modulus is 2.2. Water glass with a small modulus has strong alkalinity, while water glass with a large modulus is difficult to dissolve and has a strong inhibitory effect.

The inhibitory effect of water glass is mainly due to HSiO 3 - and H 2 SiO 3. Silicate molecules H 2 SiO 3 and silicate ions HSiO 3 - have strong hydration properties and are a kind of highly hydrophilic colloid and ion. HSiO 3 - and H 2 SiO 3 have the same acid radicals as silicate minerals and are easily adsorbed on the surface of quartz and silicate minerals to form a hydrophilic film, which increases the hydrophilicity of the mineral surface and inhibits it.