What is industrial silica sand?
Industrial silica sand is quartz sand, mostly silicon dioxide (SiO₂), that has been washed, classified and sometimes dried to meet a precise specification. It differs from ordinary construction sand in its purity, controlled grain size and low clay and iron content. The same mineral serves very different industries; the specification decides the use.
Which properties define a silica sand grade?
Specifications by application
| Application | What matters most | Typical requirement |
|---|---|---|
| Flat and container glass | SiO₂, Fe₂O₃, grain size, consistency | Very high SiO₂, very low and stable iron, narrow size range |
| Foundry moulds and cores | AFS number, grain shape, clay, refractoriness | Washed, dried, rounded to sub-angular grains, low fines |
| Dry-mix mortars, tile adhesive, grout | Grain size bands, dryness, cleanliness | Dried, graded fractions, low clay |
| Water filtration | Effective size, uniformity coefficient, hardness | Washed, sized, low fines and organics |
| Ceramics and sanitaryware | SiO₂, low iron and titanium | Fine, high-purity silica |
| Sports and leisure turf | Rounded grains, drainage, colour | Washed, consistent grading |
| Silicate and chemical production | SiO₂ and impurity profile | High purity |
Why is iron content so important for glass?
Iron oxide gives glass a green or blue-green tint. Even small changes in iron from batch to batch change the colour of the final product and force the glass plant to adjust its recipe. Glassmakers therefore value consistent iron content as much as a low average.
What is the AFS grain fineness number?
It is a foundry measure of average grain size, calculated from a sieve analysis. A higher AFS number means finer sand. Finer sand gives smoother casting surfaces; coarser sand gives better permeability so gases can escape. Foundries choose a number for each casting type.
How is silica sand processed?
Raw sand is typically screened, washed and scrubbed to remove clay, classified into size fractions and, when required, dried and cooled. Higher grades may go through magnetic separation or other treatment to lower iron. Each step is matched to the target specification.
Is silica sand dangerous?
Coarse silica sand itself is not the main hazard. The risk comes from fine respirable crystalline silica dust, created when sand is crushed, blasted or handled dry. Long-term inhalation can cause lung disease. Use dust control, ventilation and suitable respiratory protection, and follow the SDS and local exposure limits.