Silica is a chemical compound known as silicon dioxide and is basically a natural compound that is formed from the combination of silicon and oxygen in a chemical formula of (SiO2) as a tetrahedral structure.
Silica is the most abundant chemical compound in the earth’s crust because it forms part of the silicate group minerals and is the main component of quartz, the most abundant mineral on the continents.
Silica has a lot of applications in daily and industrial life, also depending on its form it can cause certain health problems that we will learn about later.
Hazards and health risks
When talking about risks and health hazards that silica can generate for humans, it is necessary to refer to the following:
- Silica found in water and ingested orally
- Silica dust entering the respiratory tract
When talking about the silica that is naturally found in water, it is known that the non-toxic value is up to 10mg/day, that is to say that completely drinkable water does not carry any risk. There is also no risk in river water.
Hazard may exist in waters near mountains with high rockfall content or near mines that crush rock.
To add, there is a study that says that the natural intake of silica in normal concentrations in water reduces the risk of suffering from senile dementia.
When talking about powdered silica that can enter through the respiratory tract They do carry a long-term risk for people who are constantly exposed to this fine dust.
Silica dust is known to cause long-term bronchitis, lung cancer and even silicosis, and it is also known to increase the risk of rheumatoid arthritis.
The people most exposed to this dust are usually mine workers. Today, the companies that generate this toxic waste must provide their workers with special masks and glasses, that is, provide industrial safety protection equipment.
Types of silica, characteristics and examples
The silica it can be classified or divided into different types taking into account the science to which they respond, for example, in chemistry there are two groups: crystalline silica and amorphous silica.
Crystalline silica
This type of silica is one that manages to form a stable chemical structure between silicon and oxygen in such a way that it has a structure and chemical formula defined as SiO2. Crystalline silica forms the different types of minerals from the silicate group, therefore its natural origin is inorganic, although currently it can also be produced in the laboratory.
Crystalline silica, also forming the most abundant group in the crust, forms a large part of the different types of rocks.
The most common examples of this group are:
- silicate minerals
- quartz
- cristobalite
- the trimidite
Amorphous silica
The amorphous silica, on the contrary, does not present an ordered atomic and chemical structure. In nature it is known as volcanic glass and also forms mineraloids. It is formed by the extremely rapid crystallization of silica and oxygen. The most common examples of this group are:
- the opal
- obsidian
- volcanic glass
- colloids and silica gel
- pumice stone
- moldavite
Mineral silica
The mineral silica it is homologous to crystalline silica, therefore, it is the chemical compound that forms all types of minerals that make up the rocks that are in the earth’s crust. The mineral silica forms the group of silicate minerals that at the same time form igneous, sedimentary and metamorphic rocks.
Silica sand
Silica sand is an industrial material that comes from sand enriched in quartz material, therefore, 95% of its chemical composition is silica. This type of industrial material is used to make glass, in metal smelting, in construction, in water purification and in the oil industry.
Lab Created Silica
It is a laboratory-created silica intended for use as a food supplement or additive, for example, in baking powders, protein powders, and dried spices. It is also used in cosmetics, in the construction industry and in electronics and is known as synthetic silica.
Properties and characteristics of silica
| SiO2 | silicon dioxide |
| SiO2 molecular weight | 60.08g/mol |
| Silicon Dioxide Density | 2.648g/cm3 |
| melting point of silicon dioxide | 1,713°C |
| boiling point of silicon dioxide | 2,950°C |
| Density | 2.533 gr/cm3 |
| crystalline silica | Transparent to semi-transparent |
| amorphous silica | opaque |
| Poisson’s ratio | 0.17 |
| Thermal conductivity | 1.1W/mK – 1.4W/mK |
| Relative dielectric constant | 3.7 – 3.9 |
| energy bandgap | 8.9eV |
Silica is a chemical compound with high melting point and high boiling point, which is why it is also considered an excellent ceramic material that is used in conjunction with clays to create various ceramic materials and refractory materials.
As for its color, it is generally transparent, but it almost never occurs in a pure way and usually presents slight impurities with other minerals and metals that give it various shades such as red, blue, white, black, green, pink. This is reflected in the different types of quartz that appear in nature.
As for its hardness and resistance, silica is a material that is quite resistant to wear and weathering processes that occur in the environment, in addition, it is hard and is considered an abrasive material, capable of being used in industry even as a substitute. of the garnets that are the abrasives par excellence. Finally, it is a material resistant to acids and water.
Silica is also considered a nearly inert material, meaning that it does not react with other chemical compounds, liquids, or gases. This characteristic gives it various industrial and common uses such as water purification.
Where is silica found?
Silica can be found naturally in the rocks of the earth’s crust, in sediments, in the human body, in food, in plants, and in animals. Next, we describe each of these.
Inorganic silica
Silica makes up the most abundant minerals in the earth’s crust, that is, the different types of silicates. These minerals are part of the structure of igneous, sedimentary and metamorphic rocks.
It appears in various types of minerals and is even part of a lot of gemstones.
Organic silica
Although organic silica is theoretically a misnomer, it actually refers to the silica that appears inside the human body, in food, on vegetables or plants, in animals, and even in water.
In the human body its function is not known exactly, however, it is part of various tissues, ligaments, muscles and cartilage.
In vegetables and grains it appears in:
- dark green leafy vegetables
- some grains and cereals, such as oatmeal and brown rice
- vegetables, such as beets and bell peppers
- alfalfa
Uses of silica What is it for?
General uses and applications
- It is used in the construction industry in the production of concrete or concrete.
- In the crystalline form it is used in the oil industry in hydraulic fracturing (fraking).
- It is the main material for making glass
- It is used as an additive and complement in refractory materials such as brick or cement.
- It is also an additive in ceramic products such as tableware.
- It is used as an anti-caking agent in powdered foods such as spices.
- Used as a clarifying agent in juices, beer and wine.
- Also appears in some pharmaceuticals
- It is used in toothpaste to remove dental plaque.
- It is an abrasive material
- It’s part of a bunch of precious stones
- in water purification
To make glass
One of the most important uses of the silica It is in the industrial manufacture of glass. It is an indispensable material for making glass windows, glass bottles storing drinks and food.
It is also used in the manufacture of glasses and special laboratory containers, for example, test tubes or acid containers. Let us remember that this chemical compound is not very reactive and resistant to high temperatures.
Industrial uses and in metal casting
With the silica Molds used in metal casting can be made to give specific shapes to these materials. The chemical compound resists very well to the heat subjected to molten materials. With this technique, engine components, faucets, and some metal parts are created.
As abrasive material
The crystalline silica either made in the laboratory or as a quartz mineral is used as an abrasive material. In this case, the silica crystals are ground and then, by using special pressure tools, they are used to polish and cut wood or metals.
To purify the water
Also, here we use the crystalline silica which has regular and homogeneous grains in industrial water filters and home filters. What is done is to place layers of material with different sizes inside the filters in order to prevent the passage of dirt and ultimately make the water drinkable.
Applications in the construction industry
The silica It is a very important additive in various products used in construction, for example, in special cements, in various types of tiles, in tiles, in mortars, in floors and walls. It is also part of stucco and is an additive to asphalt.
In electronics
The silica crystals They are capable of vibrating at very precise frequencies, this makes it very useful for manufacturing crystal oscillators that are used in electronic devices such as laptops, televisions, GPS. With the help of silica, very precise radio and television signals can be transmitted.
In precious stones and jewelry
Now you know that silica is the main component of many silicate minerals, however, some of these minerals are so beautiful and rare that they are classified within the group of precious stones, for example:
- rose quartz
- citrine quartz
- the amethyst stone
- black tourmaline
- the topaz stone
- the agate stone
- garnets
Uses in paints
Another important application that silica has is as an additive in paints. Here it meets the objective of making the paint more resistant to cracking, dirt, moisture and the appearance of Mold. It also manages to improve the reflective properties and brightness of the paint, especially white.