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Sodium Silicate – Molecular formula nSiO₂:Na₂O – is a versatile product that can be used to adhere, buffer pH, agglomerate, immobilize, coat and disperse.

Sodium silicate is made in two primary ways.

FURNACE PROCESS Silicon dioxide (silica sand) is fused with sodium carbonate (soda ash) in a furnace. This process allows for ratios of silica (SiO₂) to Na₂O from 2.0 to 3.4.  Glass briquettes (also lumps) are produced that can be sold as is or dissolved in water to produce sodium silicate solutions. 

HYDROTHERMAL PROCESS Silica sand is dissolved in sodium hydroxide solution. This process creates lower ratio silicates (<2.4) and requires less heat.

The ratio of SiO₂ to Na₂O impacts many properties of silicate such as solubility, drying rates and physical properties such as viscosity and density. Silicate products are selected based on the end application.

Most often liquid silicates are utilized due to easier handling in the end application. PQ provides silicate in various forms including solid glass, hydrous powders and ready-for-use liquids. Our liquid sodium silicate is the core building block for PQ’s derivate products that include silicas and zeolites.

Silica

Silica – Molecular formula SiO₂ – is a synthetic and amorphous form of silicon dioxide. Synthetic silica can be used as a matting agent, free flow agent, carrier, anti-caking aid, defoamer, rheology modifier, polishing agent and as an abrasive. Depending on the manufacturing method, there are different forms of synthetic silica; fumed, colloidal, precipitated and silica gel.

Each form has its own advantages ranging from pore size, surface area, moisture absorption and cost. PQ produces precipitated silica and silica gel. Liquid sodium silicate is neutralized with an acid to produce silica. In its final form, silica looks like a fine white powder.

Silica Gel

Silica Gel have a tightly controlled pore size distribution, high surface areas and pore volumes ranging from low to ultra-high.

PQ produces both hydrogel (higher moisture content) and xerogel (low moisture content). Sodium silicate is reacted with acid, normally sulfuric acid, then it is washed, dried, milled to desired particle size and packaged for delivery. PQ’s ability to tightly control particle size distribution differentiates us from competitors and provides a high-quality, consistent product.

Precipitated silica

Precipitated silicas have more open structures than silica gels. Many combinations of surface areas, oil absorptions and bulk density can be achieved in manufacturing.

This typically neutral (pH of 7.0) product is produced by reacting liquid sodium silicate and acid in a tank to produce a slurry. Solid amorphous silica is recovered from the liquid by filtration and the filter cake is then washed to remove salts and dried to the final moisture content. We also have the capability to mill the silica for specific applications.

Zeolites – molecular formula Na (AlO₂) (SiO₂)x.yH₂O – are crystalline aluminosilicate that have the ability to selectively absorb molecules and manage ion exchange. First, alumina is reacted with alkali to make sodium aluminate then zeolite is crystallized from a reaction of the sodium aluminate with sodium silicate.

This reaction creates a three-dimensional cage-like structured mineral which is capable of cation exchange or molecular adsorption. Zeolites come in multiple forms based on composition and structure. PQ specializes in 4A and P type zeolites.

Metasilicate – molecular formula Na₂SiO₃ – is a highly alkaline form of sodium silicate.

Metasilicates are uniquely qualified for cleaning. The higher alkalinity is achieved by using additional caustic soda during preparation. We produce both anhydrous (dry powder) and pentahydrate (5 parts water) forms. Metasilicate is available as a bead, granule and powder.

Specialty Silicates – Potassium nSiO₂:K₂O and lithium nSiO₂:Li₂O are specialty products that can be used as a beneficial substance for plants in agriculture and, as a binder in agglomeration, protective coatings, and treatments for concrete.

Potassium silicate is produced through a furnace process where silicon dioxide (silica sand) is fused with potassium carbonate (potash) in a furnace.  This process allows for ratios of silica (SiO₂) to alkali (a base that dissolves in water) from 1.6 to 2.5. Glass lumps or flakes are produced that can be sold as is or dissolved in water to produce potassium silicate solutions.

Lithium silicate is produced by using lithium hydroxide (LiOH) instead of caustic soda (NaOH) in reaction with silicon dioxide (SiO₂).

The specialty silicates are similar products to sodium silicate but tend to be more specialized in use.