Why Color Sort and Why Recycle?
Color is obtained by using specific additives, including naturally occurring iron oxides for green, cobalt oxides for blue, and sulfur oxides for amber. So that the chemicals used for coloring do not mix, each color is produced in a dedicated furnace. The implication is that recycled cullet content should be color sorted to be usable for each type of furnace. Single-color cullet is recycled to substitute for part of the raw materials going into the furnace, thus providing several advantages:
- Reduction in the consumption and transportation costs of raw materials (and associated carbon dioxide greenhouse gas and other toxic or harmful emissions).
- Extension of the life of plant equipment, such as furnaces by burning them at reduced temperatures.
- Energy savings in reduced fuel consumption and associated carbon dioxide and other emissions.
- Direct reduction in the landfill of the quantity of glass recycled and corresponding reduction in the cost of transportation to landfills and emission consequences.
According to the Glass Packaging Institute, energy costs drop about 15-25% when recycled glass is used in the glass-making process. Recycling one glass bottle saves enough energy to power a 60-watt bulb for four hours, a computer for 30 minutes or a television for 20 minutes. Every 10% increase in recycled glass equals a 10% decrease in sulfur dioxide; for every six tons of cullet used, carbon dioxide emissions are reduced by one ton, electricity and natural gas use is reduced by 2.5%, and the furnace temperature is reduced by 6º C; and for every ton of glass recycled, over one ton of natural resources is saved.