Perlite Perlite Perlite is a volcanic eruption of acidic lava. The glassy rock that has been rapidly cooled has been named for its pearl-fracture structure. Perlite mines include perlite, obsidian and rosin. The difference between the three is that perlite has a circular arc crack formed by condensation, called perlite structure, water content of 2 to 6%; rosin rock has a unique rosin luster, water content of 6 to 10%; black shale has glass Gloss and shell-like fracture, water content is generally less than 2%.
Perlite • Instructions for use
Main industrial indicators of mineral deposits
The industrial value of the expanded perlite raw materials is mainly determined by their expansion ratio and product bulk density after high temperature roasting.
1. Expansion factor k0>5~15 times
2. The weight is ≤80kg/m3~200 kg/m3
Quality requirements:
1. The glass is pure, the transparency is good, and the light color is mostly high quality.
2. No or slight devitrification, serious is inferior quality.
3. Contains no or little crystal matter, and contains a lot of inferior quality.
4. Chemical composition: SiO2 70%±, H20 4~6%, Fe2O3<1% for high quality, >1% for medium and low quality.
Perlite • Production process
The oxidation and melting temperatures of perlite are: initial shrinkage temperature of 1025 ° C, softening temperature of 1175 ° C, melting temperature of more than 1500 ° C, softening temperature range of 150 ° C, and melting temperature range of 325 ° C. Perlite begins to shrink at a temperature of 120 ° C lower than that of feldspar, a softening temperature of 75 ° C, and a softening range of 95 ° C. Due to these characteristics, perlite can greatly reduce the firing temperature and improve the quality of sintering in the firing of ceramic products. Through further research, the perlite also has a characteristic that the mullite crystals form earlier in the ceramic body containing perlite, which is beneficial to the unfolding of the sintering process. In this way, the perlite-containing green body has the same process characteristics as the feldspar-quartz-clay (kaolin mineral) ternary body blank formulation, and can also reduce the firing temperature (from the original 1280 ° C to 1180 ° C -1160 ° C), and has good thermal stability.