Glass Mine, the Invisible Treasure -- Recycling of Glass Wastes

The data shows that the glass wastes account for 4 to 8 percent of the total amount of municipal wastes. More than 5 million tons of glass is recycled per year in America and there is 10.4 million glass produced in China per year.

A large amount of glass wastes brings more inconvenience to our production and life, and produces a lot of load on the environment. Therefore, how should we carry out glass wastes recycling? And what are the applications of glass wastes after recycling?

The accumulation of glass wastes pollutes the environment

This article will introduce some methods and techniques of glass recycling at home and abroad, hoping you can get help.

Recycled as raw material of glass

Glass wastes can be reused as the raw material of glass after the collection, separation and treatment, which is the main approach to recycling glass wastes.

The waste glass can be put into use of the production of glasswork that has low requirements of chemical components, colors and impurities, such as colored glass bottle and can, glass insulator, hollow glass block, grooved glass, patterned glass and colored glass ball.

Glass wastes can be crushed and reused

The added volume of glass wastes in these products are commonly more than 30wt%, and the added volume of glass wastes in green glass bottles and cans are more than 80wt%.

Recycling process: glass wastes collection → washing → crushing → metal separation → ceramic and stone separation → reuse

The output size of crushing: 20mm to 40mm

Recycled as raw material of coating

A company producing fiberboard of wood in じょうそうし(Jososhi), Japan uses the glass wastes to be crushed into fine powders and mixed it into the painting in a certain proportion, which can replace the silica and other materials in the coating.

Waste glass can be reused in the coating after processing

The recycled waste glass bottles are crushed and ground into the fine glass with almost the same shape as the natural sand grains. Then the fine glass particles are mixed with the same volume of painting to improve the texture and enrich the patterns of painting.

This painting can be made into water-soluble automotive coatings. With this mixed waste glass coating on the exterior of the object, diffuse reflection can occur after irradiation. It can prevent automotive from traffic accidents and decorate the exterior of cars.

Recycling process: glass wastes collection → washing → crushing → grinding → reuse

The output size of crushing: 0.25mm

Recycled as raw material of glass-ceramics

Glass-ceramics have a hard texture, high mechanical strength, and good chemical and thermal stabilities. However, the production cost of traditional raw materials commonly used for glass-ceramics is relatively high. The waste glass and coal ash are successfully adopted to replace the traditional raw material of glass-ceramics at home and abroad.

Waste glass is reused to make glass-ceramics

This glass-ceramics is made by combining melting and sintering technology: coal ash is mixed with waste glass, melted at 1400℃ to form amorphous glass, quenched by coal water, ground by mill (ball mill or Raymond mill), and sintered under the temperature of 810-850℃.

Finally, it can be made into glass-ceramics with good mechanical properties, which is suitable for the construction field.

Recycling process: glass wastes collection → separation → washing → crushing → grinding → sieving → melting → molding

The output size of grinding: 16 mesh to 150 mesh (0.1mm-1.25mm)

Recycled as raw material of glasphalt

Glasphalt is a mixture of 30% pitch and 70% waste glass fragments. It can be applied for road construction with glass, sand aggregate and ceramics. It brings the following benefits when using glasphalt as the road-building material:

• improving the skid resistance of road surface

• improving the wear resistance of road

• improving the reflective performance of road surface and enhancing the night visuals

Glass wastes are recycled to build road

Recycling process: glass wastes collection → crushing → sieving

Output size of crushing: 0.6mm-16mm

Recycled as raw material of brick

The waste glass is used as the raw material, and an appropriate amount of plastic clay is mixed. After granulation, molding, sintering and other processes, it can be made into building bricks at a temperature of 950 to 1050 ° C for 180 to 210 minutes. This brick has the features of acid-resistant, alkali resistant, hard to fade and anti-aging, etc.

Waste glass is recycled to make bricks

Recycling process: glass wastes collection → separation → crushing → stirring → melting → pressing → molding

The output size of crushing: 0-5mm, 5-10mm, 10-20mm

Recycled as raw material of mosaic glass

Mosaic glass is resistant to heating, cold, acid, alkali and corrosion, and also has the features of non-deforming, non-fade, and easy to clean, etc. Meanwhile, the mosaic glass is easy to apply and adhered to cement strongly, which is suitable for decoration home and buildings.

Mosaic glass made of waste glass

Mosaic glass is usually made by sintering and melting. Among which the melting method is taking waste glass as the main material (the added amount accounts for 25wt% to 60wt% of the total materials), mixing a certain amount of quartz sand, feldspar, limestone, sodium carbonate, opacifier, and colorant, and sending to the melting pit (the temperature is in the range of 1400 to 1450℃).

The melting glass liquor is sending into the calender to press into the glass blocks in the required shape and size, then transporting to the annealing furnace.

Recycling process: glass wastes collection → separation → crushing → stirring with other materials → melting → pressing

Output size of crushing: 40 mesh to 60 mesh (0.3mm-0.45mm)

Recycled as raw material of artificial marble

Artificial marble is made by using waste glass, fly ash, sand and stone as aggregate, and cement as a binder and adopting the forming method of slip casting. It not only has a smooth surface and bright color, but also has good physical and mechanical properties and good decorative effects.

Waste glass is reused to make marble

Artificial marble made of waste glass has the features of wide sources of raw materials, simple structure and techniques, and low investment costs.

Recycling process: glass wastes collection → separation → crushing → stirring with other materials → melting → pressing

The output size of grinding: 80 mesh to 100 mesh (0.15mm-0.2mm)

Recycled as raw material of ceramic glaze

In the producing process of ceramic glaze, using waste glass to replace expensive frit and other chemical materials can reduce the temperature of glaze, save the costs and improve the quality of products.

Colored ceramic glaze made of colored glass wastes

Taking colored glass wastes as the glaze material can also reduce or even don't need to add colorant to save more costs.

Recycling process: glass wastes collection → separation → crushing → grinding → sieving

The output size of grinding: 80 mesh (0.2mm)

Recycled as raw material of foam glass

Foam glass, also known as porous glass, refers to a glass material filled with numerous openings or closed pores. These pores account for 80％ to 95％ of the whole volume of the glass, and the diameter of the pore is about 0.5 to 5mm.

Foam glass made of glass has many advantages

Compared to other inorganic adiabatic and soundproof materials, foam glass has the advantages of heat insulation, sound insulation, dampproof, corrosion resistance, cold-proof, etc.

Recycling process: glass wastes collection → separation → crushing → grinding → sieving → mixing → burning(500-730℃) → foaming → cooling

Output size of crushing: 200 mesh to 300 mesh(0.05mm-0.074mm)

Conclusion

Recycling one ton of waste glass containers can save raw materials: 600 kg of sand, 200 kg of soda ash, 180 kg of limestone and 85 kg of feldspar.

Reusing recycled glass to regenerate glass can save coal and electricity energy by 10% to 30%, reduce air pollution by 20%, and reduce waste gas producing from mining by 80%.

Recycling a glass bottle can make a 100-watt bulb light for 4 hours, run a computer for 30 minutes, and watch 20 minutes of television.

Glass recycling brings more benefits to our life

In summary, the utilization prospects of waste glass are very broad. The recycling of waste glass has been a common issue for the world's environmental protection industry and industrial enterprises. It has certain economic and social benefits which is a difficult task that requires each of us to take action.