Silica use and applications

Silica Use

Silica usage and safety

Silica is the second most commonly found mineral on earth and comprises almost thirty percent of the Earth's crust by weight. (Silica Dust Exposure) Silcia, or silicon dioxide (SiO2) also known as alpha silica or free silica, is described as a crystal which is "... tiny, very hard, translucent, and colorless" (Silica Dust Exposure).

This substance way discovered in 1824 by the Swedish chemist Jons Jakob Berzelius. (SILICON or SILICA) it has an atomic number of fourteen and has various metallic characteristics. An important fact is that silica is never found in its natural state but as a silicate ion (SiO4), combined with oxygen. (SILICON or SILICA). It is found in silica-rich rocks such as obsidian, granite, diorite, and sandstone. Feldspar and quartz are the most significant silicate minerals. (SILICON or SILICA). Silica is also be found in "... skeletal parts of various protists and animals, such as certain sarcodines diatoms, and sponges, and in the stems and other tissue of higher plants" (Silica).

2. Usage

This mineral is an extremely important component in many industries. As one study states; "The importance of silica cannot be disputed and it is difficult to envisage a world which places major restrictions on its use" (Lavender M. 1999). Silica occurs in manufacturing and industry in a number of different forms and its use is described as 'ubiquitous'."..in the daily life of the whole population" (Lavender M. 1999).

Basically silica is processed into two intermediate products; namely silicon and ferrosilicon. (SILICON or SILICA). In modern industry this mineral has a myriad of different uses. These include the following. It is used in the making of common glass as well as filler for paint and rubber. Silica is also used extensively in the chemical industry and in construction. An important aspect of its usage is its use in construction; as well as in the preparation of other substances that are used in industry, such as silicon carbide; which is in a common abrasive marketed under names such as Carborundum. (Silicon carbide) it also used in specialized optical apparatus. (Silica)

Silica is also extremely important in the manufacture of different types of steel and cast iron, as well as in aluminum alloys. Other uses of this material include its importance in the cosmetics industry as a filler, its use in the building industry as a component of hydraulic cements and as an important element in the pharmaceutical industry. Other uses of silica in different industries include the following:

As a rubber reinforcing agent - especially for high adhesion to textiles.

Ferrosilicon alloys are used to improve the strength and quality of iron and steel products. Many tools are made of steel and ferrosilicon.

As an anti-caking agent in foods.

As a flatting agent in paints.

As a thermal insulator.

As an ablative material in rocket engines, spacecraft.

The use of silica fibres in the plastics industry to produce reinforced plastic.

SILICON or SILICA).

In the aluminum industry silica or silicon is used to improve castability and weldability. (SILICON or SILICA). In the chemical industry, "...silicon metal is the starting point for the production of silianes, silicones, fumed silica, and semiconductor-grade silicon" (SILICON or SILICA). Silanes are used in the manufacture of silicone resins, lubricants, anti-foaming agents, and water-repellent compounds. (SILICON or SILICA)

One of the central aspects that have been noted as a reason for the extensive use of silica in industry is the special qualities that it offers. One such quality is its low thermal coefficient of expansion. "...it withstands sudden changes in temperature and can be used in parts that are subjected to wide ranges of heat and cold. Unlike ordinary glass, it does not absorb infrared and ultraviolet light" (Silicon Dioxide or Silica).

Part of the reason for Silica's extensive usage in the computer industry is due to this quality and its importance in the manufacture of computer components that are subjected to changes in temperature. Furthermore, Silicon is considered a semiconductor; "...which means that it conducts electricity, but not as well as a metal such as copper or silver. "This physical property makes silicon an important commodity in the computer manufacturing business" (SILICON or SILICA) as a result "Ferrosilicon accounts for 53% of the annual silicon consumption in the United States; pure silicon accounts for the remaining 47%" (SILICON or SILICA)

3. Safety, storage ad worker protection

3.1. Health risks

In most respects silica or silicon dioxide is an inert substance which is relatively harmless to humans. If it is ingested it will pass through the human system without any ill effects. However silica is often associated with silicosis, a lung disease especially found in miners. The inhalation of fine silica dust in large enough quantities can lead to this disease. This is often the case in people who work in close proximity to large quantities of silica dist, such as in sandblasting. This process is explained succinctly as follows;

Silicosis is lung damage caused by breathing dust containing fine particles of crystalline silica. If silica particles are inhaled they become embedded in the lungs, the lung tissues react by developing fibrotic nodules and scarring around the trapped particles. The scare tissue makes the lungs hard and stiff. The scaring can greatly reduce the function of the lungs making it difficult and sometimes painful to breathe.

Silica Dust Exposure)

As mentioned above, silica is prevalent and even ubiquitous in contemporary society and therefore poses a real threat to health in some respects, especially in industry. As one study on the subject states;

Every year more than one million American workers are exposed to silica dust at their jobs. Deaths from silicosis currently number about 300 cases per year. Hundreds more are being permanently disabled by this disease. Every one of these cases is an unnecessary tragedy, because silicosis is absolutely preventable

Silica Dust Exposure)

Among the different types of situations and occupations that are prone to health risks from exposure to silica are the following;

Construction: sandblasting, rock drilling, masonry work, jack hammering, tunneling;

Any occupation where workers are handling rock, brick, sand, or drilling, quarrying, or tunneling

Foundry work: grinding, moldings, shakeout, core room;

Glass manufacturing;

Manufacturing of soaps and detergents;

Paper and pulp mills: repair or replacement of linings of rotary kilns;

Food processing operations: preparing crops for market, sorting, grading, and washing.

Silica Dust Exposure)

3.2. Safety measures

It therefore follows that employers are particularly responsible for ensuring the safety of staff that are exposed to silica and silica products. The first and most obvious safety measure is the control of exposure to silica dust. Another measure that is often used is the minimization of silica dust through the application of water in the process or in cleaning. (Silica Dust Exposure) Other measures include the use of exhaust ventilation to remove the silica dust form the area as well as dust control methods such as vacuuming with a high-efficiency particle air (HEPA) filter. (Silica Dust Exposure)

There are also various administrative controls that can be implemented; such as the monitoring of the air in the workplace. Training is another aspect that is recommended and all employers should train their staff in the dangers of exposure to this substance; as well informing staff about the particular operations and processes that produce the silica dust. Personal hygiene is also a factor of the safety process and all workers should be informed about in order to avoid unnecessary exposure to this substance. Lastly, regular medical examination are necessary to ensure that workers and others have not been affected by exposure to silica should be undertaken.