Basic characteristics of perlite
Perlite is a naturally occurring volcanic glass containing 70-75 % silicon dioxide SiO2 and 2-5 % water Н20.The water content is a crucial factor for the specific properties of this mineral. The crude perlite rock is expanded by exposure to rapid heating. This expansion process creates lightweight granules which due to their extraordinary properties offer a variety of application possibilities.
- low density
- air porosity
- ultimate water storage capability
- grain stability
- non-combustible (fire-protectionclass A1)
- heat insulating, sound-proof
- resistant to moisture
- rot resistant, safe against vermin
- eco-friendly because of its easy recycling and disposal
Application areas of perlite
The product is used in a large number of applications. These include:
Building material industry
A classical application for perlite is its use as masonry fill in the hollow cores of masonry cavity walls and roofs. The loose granules are used for thermal and acoustic insulation as well as for height compensation. Furthermore, perlite is applicable to use as lightweight aggregate in plaster, plaster base, mortar, screeds. A number of heat insulation products (insulating boards, building panels) are made of perlite.
Agriculture and horticulture
Mixed with soil, perlite has a positive effect on the ground – as it protects against excessive compaction significantly improving the aeration, perlite also prevents waterlogging. Perlite encourages an uniform distribution of the root structure around the plant material. It protects the roots from freezing and overheating. Without being mixed with soil perlite has successfully proven itself to be an outstanding propagation substrates for plants as well.
Perlite filter aid for chemical, pharmaceutical and food industries
Perlite is the most commonly used filter aid that meets all requirements. Compared to other filter aids it is characterised by product’s harmlessness in terms of health and ecology: it has a neutral pH value between 6,5 and 7,5, is chemically inert, highly stable and almost insoluble. Moreover, no tastes, odors and colors are imparted. Perlite filter aid is being utillized in a wide variety of applications like chemical, pharmaceutical and food-related industries. For instance, it is widely used in the clarification of apple juice concentrate as soon as in the brewing of beer and production of vegetable oils and different soft drinks. Perlite has also proven its usability for wastewater treatment, filtering of chemicals and pharmaceutical products.
Cryogenic Applications for Insulation
Because of its unique properties, perlite is applied for insulating of cryogenic and low temperature storage tanks, where super-cold gases may be stored or transported in a liquid state. So perlite is used in the shipping industry for the construction of Liquefied Natural Gas (LNG) tankers as a material for tank insulation as well as in refrigeration as filling for coolers in the air separation plants.
Perlite in metallurgy
Perlite is used in casting of iron and steel for insulation of level of metal melt in casting ladles and moulds. The expanded perlite with a grain size of up to 5 mm shall be thrown in paper or polypropylene bags onto the level of metal melt. When touched a fused metal the bag explodes and burnes down, whereas expanded perlite get widespread over all the level of metal melt. A formed insulating film prevents fast cooling of the molten metal. Admixtures and slag get transformed into a profitable part, whereby the quality of the base metal improves.
