Silicon and oxygen are the earth's two most abundant elements and together they make silica, one of the earth's three most common rock forming minerals.
Silica occurs in three main crystalline forms. The principal occurrence is as the mineral quartz but it also occurs in other rarer mineral forms known as tridymite and cristobalite. It is a very durable mineral resistant to heat and chemical attack and it is these properties that have made it an essential raw material for many industrial and societal applications.
The first industrial uses of crystalline silica were probably related to metallurgical and glass making activities a few thousand years BC. It has continued to support human development throughout history, being a key raw material in the industrial revolution especially in the glass, foundry and ceramics industries and is imperative for the development of the green revolution, notably renewable energy. Silica contributes to today's Information Technology revolution and is a primary component of mobile phones and tablets.
Silica (industrial) sands contain a high proportion of silica (normally, but not exclusively, more than 95% SiO2). It is recognised by government as an essential raw material of national importance and as such there is a requirement to provide an adequate and steady supply, through maintaining stocks of permitted reserves and safeguarding silica sand resources.
The main end uses of silica sand are:
Silica is the major ingredient in virtually all types of glass. The principal glass products include containers (bottles and jars), flat glass (windows, mirrors, vehicle glazing, etc.), lighting glass (light bulbs, etc.), tableware (crystal, drinking glasses etc.), personal mobile devices, decorative glass, fibreglass, optical glass and vacuum flasks.
Silica has a high melting point, 1610oC and is used extensively in the ferrous and non-ferrous foundry industries. The high melting point enables castings to be produced by pouring molten metal into moulds made out of silica sand. This is critical in producing aerospace, military and automotive components.
Silica that has been ground to fine size is an ingredient of most clay bodies and is a major constituent of ceramic glazes. Typical everyday products include tableware, sanitaryware, ornaments and wall and floor tiles.
Closely sized grades of silica sand are the principal filtration medium used by the food and water industry to extract solids from potable and wastewater.
The construction industry is founded on silica and there are a host of specialist industrial applications where technical grades requiring exacting tolerances are necessary for a range of building products including silica and aerated concrete blocks, floor and roof tiles, flooring and rendering compounds, roofing felt and cement and resin injection systems.
Silica sand is used for equestrian surfaces, in artificial turf, golf course root zones, bunkers and top dressings, football, rugby, cricket and other sports pitch construction and surface dressing and as well as children’s play sands.
Silica sand has a variety of safety applications in transport, including reflective surface applications such as white line markings and of increasing importance, rail braking medium, where the sand is used to increase the grip under braking. All new trains require sand braking systems, with the existing rolling stock also being retro-fitted. Silica is also used in the manufacture of chemicals and metals, fillers in numerous products, plastic and otherwise, the manufacture of refractories, biomass energy generation, and as additives in agricultural and horticultural products. It is difficult to imagine modern life without silica!
High grade silica sand is usually found as unconsolidated deposits below thin layers of soil and overburden. After quarrying, the sand routinely undergoes processing before sale. The processing may include washing and cleaning of the grains, sizing to remove coarse and very fine fractions, and physical and chemical processes to remove iron, chromium and other deleterious minerals, such as through magnetic separation. After processing, the sand may be dried and some applications require it to be ground in ball mills to produce very fine material.
A constituent body of MPA, the Silica and Moulding Sands Association (SAMSA) was established in 1941 and has represented the interests of MPA's silica sand producers for 80 years. In 2019, SAMSA commissioned the British Geological Survey to review and update the Government commissioned Mineral Planning Factsheet on Silica Sand. The most downloaded factsheet in the suite, the new factsheet was published in January 2020 and is available from www2.bgs.ac.uk/mineralsuk/planning/mineralPlanningFactsheets.
This factsheet provides an overview of silica sand supply in the UK. It is one of a series on economically important minerals that are extracted in Britain and is primarily intended to inform the land-use planning process. It is not a statement of planning policy or guidance; nor does it imply Government approval of any existing or potential planning application in the UK administration.
Please contact SAMSA for further information.
The Mineral Products Association (MPA) is the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and silica sand industries.