Tell us about getting refractory glass and crystal glass. Write the equations of the processes occurring during this process.

If you take potash, lead oxide and sand as raw materials for making glass, you get crystal glass. The substances are mixed and heated strongly:
К2СО3 + SiC2 -> K2SiO3 + CO2
the addition of lead oxide increases the refractive index of the glass and the dispersion of light in it. The addition of barium oxide generally only increases the refractive index.
The composition of crystal glass is expressed by the formula K3O * PbO * 6SiOi
Refractory glass — glass of conventional composition, in which alkaline components in the feedstock are replaced with boron oxide (B2O3). It differs from ordinary glass by increased thermal stability and increased resistance to mechanical damage.