The microspheres are a waste material arising in the process of combustion of hard coal. The product is made of spheres with a diameter of 10-800 microns, filled with gas, mostly CO2 and NO2. Sheaths of the spheres are 0.2-3 microns thick, what makes the microspheres have a great volume at a relatively low gravity. Material contains mainly:
silicon oxide (SiO2), aluminum oxide (Al2O3), magnesium oxide (MgO), iron trioxide (Fe2O3), potassium oxide (K2O), calcium oxide (CaO) and vestigial admixtures of other metals.
Chemical Composition
SiO2 57,9 ± 5,0%
AL2O3 35,8 ± 2,0%
Fe2O3 1,5 ± 0,3%
CaO 1,1 ± 0,2%
MgO 1,6 ± 0,2%
SO2/SO3 0,6 ± 0,3%
K2O + Na2O 1,2 ± 0,4%
TiO2 0,8 ± 0,3%
Cl 0,2 ± 0,1%
