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August 1, 2009

The Glass Recycle Process

Processing: Producing glass cullet

After the sorting stage, the next stage in the glass recycle process involves crushing and grinding the waste glass into tiny pieces. This finely crushed glass pieces are referred to as cullet.

Processing: Removing contaminants

The next stage in the glass recycle process involves the removal of contaminants from the glass cullet.
The glass cullet is passed through a magnetic field, where metal contaminants like metal bottle caps are removed from the glass. Other contaminants like paper and plastic are picked up manually or through an automated process.
Ceramic contaminants are removed from the glass cullet via a process known as fine sizing. The finely ground glass cullet is passed through various screens, leaving behind ceramic residues.
If, however, ceramic contaminants do pass through the various screens together with the glass cullet, the quality of the recycled glass will be affected. Ceramic contaminants in glass can lead to structural defects.

Processing: Making recycled glass

The cullet is then melted.
This glass cullet can then be used in manufacturing recycled glass products like new glass containers, bottles .

Processing: Decolorizing and dyeing

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.

Processing: Making recycled glass products

In the last stage of the glass recycling process, the recycled glass, colored or clear, is then molded into the various products and sold in the markets.

Other facts about recycling glass

An interesting point about the glass recycling process is that glass can be recycled as many times as required, without any deterioration in quality.
What makes glass recycling even more important is that glass never decomposes. If disposed of in the landfills and incinerators, they will contribute substantially to pollution. Hence, it is particularly to send your unwanted glass ware for recycling.

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