Precipitated silica, a form of synthetic amorphous silicon dioxide, is derived from quartz sand, a crystalline form of silicon dioxide. The physical properties of precipitated silica can be manipulated during the manufacturing process to deliver products with a wide range of performance-enhancing features engineered for many different end-use applications.

As one of the first manufacturers of precipitated silica, PPG has more than 80 years of experience designing and manufacturing precipitated silica for customers in the following industries:

• Tire
• Industrial rubber
• Silicone rubber
• Footwear
• Food
• Feed
• Agricultural and Industrial
• Coatings, paints and inks
• Adhesives and sealants
• Battery separator

Here is a brief look at how precipitated silica is made:

Step 1: Precipitation

Sodium silicate solution (water glass) and mineral acid are reacted in an agitated vessel to produce a slurry of amorphous silica particles. The critical physical properties of precipitated silica, such as particle size and porosity, are controlled during this stage of the process by manipulating, among other things, the composition, concentration, and ratio of reactants in the precipitating solution; the speed of agitation; the reaction time; and the reaction temperature.

Step 2: Washing

The precipitated silica slurry is then concentrated to form a filter cake. The product filter cake is washed to remove the salt byproduct that is produced during precipitation.

Step 3: Drying

The silica filter cake is then dried to the desired final product moisture content.

Step 4: Finishing and packaging

The dried silica is then finished to achieve the desired final product form. This can include: agglomeration or compaction into a low-dust form, or milling and classification to the required particle size distribution. The final product is packaged for shipment in small bags, big bags, or bulk trucks or railcars.