Silica sand, also known as silicon dioxide or quartz sand, is a naturally occurring granular material made up of finely divided quartz crystals. It is one of the most abundant minerals on earth and has a wide range of uses due to its unique physical and chemical properties.
Silica sand is mainly formed as a result of the slow erosion and weathering of rocks with high silicon dioxide (SiO2) content, like quartz and feldspar. These boulders are gradually reduced in size by wind and water, and the quartz and other minerals they contain are separated and dumped in places like riverbeds, beaches, and deserts.
Other sedimentary layers may bury the silica sand grains as they amass, exerting pressure that can make the sand compact and cement it together. This process of lithification can lead to the formation of sandstone, a type of sedimentary rock composed mainly of mineral grains the size of sand, rock, or biological material.
Weakly cemented sandstones and loosely consolidated sand deposits found below thin layers of soil can be crushed to create silica sand. It is further processed into various sizes for commercial and industrial uses. The processing of the product typically involves washing, scrubbing, sizing, and magnetic separation to remove impurities, which makes it consistent and free of contaminants.
The uniform size and shape and chemical resistance properties of silica sand make it one of the most widely used materials in various end-use sectors, including:
- Construction
One of the major end-users of silica sand is the construction sector. The sand is used as a primary component in the production of concrete and mortar, as well as in the manufacturing of glass and ceramics. It is also mixed with cement, water, and other additives to create a strong and durable building material that is used in the construction of roads, bridges, buildings, and other structures.
Furthermore, silica sand is used in autoclaved aerated concrete as a replacement for pulverised fuel ash (PFA). As the production of coal-fired electricity and consequently pulverised fuel ash is declining, the silica sand market is likely to grow in the forecast period.
- Water Treatment
Silica sand is applied as a filtration medium in water treatment applications due to its excellent chemical and thermal stability, combined with its ability to effectively remove impurities from water. The sand is also used to remove particles, organic matter, and other contaminants from the water, ensuring the optimal safety and quality of potable water.
- Oil and Gas
In addition to its use in the construction and water treatment sectors, silica sand is used in the oil and gas sector. It is a primary component in hydraulic fracturing, a process used to extract oil and gas from underground reserves. Moreover, the sand is mixed with water and chemicals and pumped into the ground under high pressure, creating fractures in the rock formations and enabling controlled release of oil and gas. The product is also utilised as a proppant to increase the production of oilfield reservoirs, where strict control over grain size, shape, and contaminants is required.
- Sandblasting
The abrasive nature of silica sand makes it an ideal material for use in sandblasting. Sandblasting is a process that involves propelling sand particles at high velocity to remove paint, rust, and other contaminants from metal surfaces. Silica sand is a popular choice for sandblasting due to its hardness and low cost.
- Sports
Silica sand finds usage in the sports and leisure sector, and it is a primary component in the construction of golf courses and artificial turf playing fields. The sand helps to ensure that the grass stays in place while providing a soft and cushioned surface for athletes to play on.
- Leisure
In addition to its industrial uses, silica sand is also used for recreational purposes. It is a popular material for use in sandboxes, beach volleyball courts, and other outdoor recreational areas. The sand’s fine, granular texture and natural appearance make it an ideal choice for these applications.
- Glassmaking
Due to its clarity and high level of chemical purity, silica sand has been used for all forms of glass in the glassmaking sector. Soda-lime-silica glasses make up the majority of the commercial glassware used in daily life, including bottles and jars (containers) and flat glass (windows, mirrors, and vehicle glazing). These products have a silica content of between 70 and 74 per cent, with silica sand serving as their primary source.
- Foundry
The foundry sector also utilises silica sand as the major core and mould-making material for ferrous as well as non-ferrous castings. Its clay-free property, high level of silica, and availability of uniform size distribution make it an excellent material for use in foundry materials.
Other Applications of Silica Sand
Silica flour is used as a filler in plastics and paints. In the manufacturing of glass fibre and rubber sealants, where colour consistency is essential, silica sand is utilised as a crucial raw material. Tile adhesives and grouts use the product as a filler; silica sand, moreover, acts as an inert particle during the burning of fuels in fluidised bed boiler sands to generate biomass energy.
In addition to this, silica sand helps in boosting the grip during braking, which is surging its demand to enhance the safety of rail braking systems.
Conclusion
Silica sand is a highly versatile and essential raw material that has a plethora of applications in various sectors, ranging from construction and glass manufacturing to foundry and fracking. Such factors also make it a building block of modern society. In the coming years, not only factors like rapid urbanisation, population growth, and rising manufacturing activities are expected to boost the demand for silica sand but also the increasing decarbonisation attempts are likely to surge the use of the product in smart screen and solar panel technologies.
However, concerns regarding the environmental impact and issues like soil erosion and biodiversity loss of mining silica sand have been raised. Hence, it is increasingly becoming essential for companies to formulate innovative methods to responsibly source silica sand.
