To produce recycled glass of the desired glass, the recycled glass has to undergo glass decolorizing in the glass recycle process, followed by dyeing.
The first step in the decolorizing process includes oxidizing the melted glass cullet.
For green glass, the oxidation process turns the deep dark green color to yellow-green color. A chemical known as manganese oxide is then mixed with the glass cullet to it grey. The grey base is usually used as the primary color to which various other coloring dyes or agents are added to develop glass of various colors.
For brown or amber-colored glass, zinc oxide is added instead to oxidize the brown glass cullet to blue or green cullet, depending on the quantity of zinc oxide added and the richness of the brown or amber-colored glass being recycled.
If the clear recycled glass is required, erbium oxide and manganese oxide are added to the glass cullet to help clear all the colors from the glass cullet.
Some of the most commonly used coloring agents for dyeing of recycled glass include borax, potassium permanganate, zinc oxide, erbium oxide, cobalt carbonate, neodymium oxide, and titanium dioxide.
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