Perlite is used as an additive to casting sand in foundry industry. Insulation property of perlite cause to decrease the speed of molten materials solidification and foundry problems.
Permeability of perlite removes lightweight gases from environment, increases the ability to cool and heat the foundry sands by adding perlite, thus reduces the defect and weakness of the expansion operation, then causes saving in time and cost of cleaning foundry parts. Also while casting expanded perlite is used for heat retention at melting level.
For removing slag of molten materials and heat retention of casted parts
Perlite with high permeability is used as additivtive material to sand and in foundry causes to remove gases and quick heat transfer, due to this reason is produced most clean molds without captive bubbles.
By adding perlite to foundry molds or sand reduces the ejection or swelling defect, the wasted and appendixes are almost eliminated and will be no need for trimming and polishing.
Expanded perlite is consuming at high amount in metallurgy. It is known produced hot cast iron requires temperature of 800 C°. By covering and insulating hot cast iron with expanded perlite powder, along with preventing from wasting materials reduces contraction and top parts of mold does not produce cavities, papinics and taping.
Raw perlite if applied as a single layer on molten materials, prevents oxidation of molten material, reducing the temperature drop and collecting slag.