The main ingredients in glass are silica, aluminum, and feldspar, calcium carbonate and small amounts of e.g. magnesium and potassium oxides. Resources involved are sand, metals, energy, and colorants.
Recycling happens much like manufacturing.
It is remelted and fed to a furnace which melts, then refines the materials. Heat is applied by prheated combustion air, radiation from furnace walls, and to a lesser extent from diurect heat. Molten glass flows to the refiner. Heat is recovered. Glass is then molded.