Perlite is a rock that can be found in places of volcanic eruptions. It is formed where the red-hot lava comes into contact with the earth at the edges of its stream. Due to the fact that the hot stream here cools faster, obsidian is formed - volcanic glass. In the future, if obsidian is exposed to water, it is hydrated and the substance is perlite - obsidian hydroxide.
The chemical composition of perlite (silicon dioxide, water, other elements) allows you to get a kind of "popcorn" at a temperature of 1200 degrees, when water substances expand, and the volume of perlite increases up to 20 times. It turns out the so-called perlite sand, which has unique physical properties. It is fireproof, chemically inert, lightweight, resistant to mold, rodents and microorganisms. Perlite is a material that is relevant for construction, medical, oil refining and gas industries, and metallurgy. It is successfully used at temperatures from minus 260 to plus 1000 degrees.
Perlite sand is mainly used for filling cavities during insulation works, during finishing operations to improve sound insulation (3 cm perlite replaces 15 cm bricks and provides noise absorption of 51 dB), to facilitate construction solutions in specific gravity or to improve the quality of metallurgical alloys.
After heat treatment,
expanded perlite retains its properties for an unlimited amount of time. In appearance, perlite is a white substance in granules from 0.1 to 1.0 cm, having a bulk density of 50-150 kilograms per cubic meter. Maybe that’s why the name perlite comes from the word “pearl” - “pearl” (Fr.).
How good is perlite? Perlite is a completely environmentally friendly product. It consists of additives in the form of potassium, sodium, aluminum, iron, calcium, sodium, which make it possible to successfully use this product in agriculture, especially in regions with badlands and an arid climate. Agroperlite is used for loosening soils, as an addition to various substrates, as well as a substance that holds up to 600% of water from its own weight, which reduces the number of irrigations. Perlite for plants is used in such a direction of agriculture as hydroponics.
When we eat some, for example, Dutch vegetables or berries (strawberries), we don’t realize that they were not grown in the ground, but in containers where the nutrient solution was served. And partly these containers were filled with perlite.
Various filters and sorbents are made from perlite, as well as sorbents that are highly absorbent and are therefore used to remove stains of oily liquids from water surfaces, treat sewage, improve the quality of drinking water and even localize radionuclides in the soil. In addition, materials made from it allow vacuum-free isolation of cryogenic blocks, including in metallurgy, for the separation of air into nitrogen and oxygen.