Glass recycling
As glass recycling is collecting and material recycling of used glass , referred to mostly as food packaging, the waste glass is melted. The refilling of glasses, on the other hand, is a more direct method of reuse.
Glass manufacturing
Glass is mainly made from quartz sand ( silicon dioxide ). Quartz sand makes up 12% of the earth's crust . Other components of glass are lime , ash , dolomite and soda . Glass is used in a variety of different products: packaging, tableware, windows, building glass, mirrors, optical devices, devices for chemical-technical applications and many others.
Glass recycling is considered the archetype of modern circular economy . The production of glass from old cullet saves raw materials and, above all, energy - melting the raw material mixture takes less time and lower temperatures.
Thanks to glass recycling and the use of modern technologies, the energy consumption in glass production has fallen by 77% since 1970. There is evidence that glass was recycled as early as ancient Rome. Off the coast of southern Turkey, researchers discovered a ship that was around 1000 years old with waste glass as cargo.
In Austria, for example, waste glass (used glass packaging) has been systematically collected from private households as well as commercial and industrial companies since the mid-1970s. Over 80% of the glass packaging that comes onto the market in Austria is collected and recycled.
FEVE provides an overview of the recycling rates in other countries.
Recycling of waste glass
The collection of waste glass is generally done by throwing it into public glass containers, separating according to color. In Germany, a distinction is made between white, green and brown glass. Special colors such as blue or red glass are recorded with the green glass. In Austria, a distinction is only made between uncolored glass packaging (white glass) and colored glass packaging (stained glass). The color separation is important for the recycling process, because a green champagne bottle, for example, leads to unwanted color casts in the melting process for colorless glass. Conversely, the addition of colorless (white) glass to a melt for colored glass leads to glass defects and undesirable color changes in the finished product. Stained glass is used for products that require light protection (e.g. milk, medicines, and beer). In the meantime, it is also possible to separate shards of mixed colors with the help of electro-optical sorting machines; However, the sorting result is also improved here by a previous separate recording of the different colored types of glass.
In Austria, more than 200,000 t of used glass packaging is collected annually, that's around 700 million pieces. Around 2 million tons of recycled glass are collected in Germany every year. The recycling rate is 87% and 94% in Switzerland.
The collected glass packaging is raw material for the production of new glass packaging. Their share can be 60 to 90% of the raw material mix in the glass factory (around 90% for green glass, around 60% for white glass). In Austria, glass is recycled in the glass works of Vetropack Austria GmbH in Pöchlarn / Lower Austria and Kremsmünster / Upper Austria as well as Stölzle Oberglas GmbH in Köflach / STMK.
The used glass packaging is melted down and formed into new ones (bottle-to-bottle recycling without loss of quality). Before it is melted, the glass waste is freed of the wrong types of glass, pieces of glass of the wrong color and foreign substances by hand and machine. In the recycling process, between 3 and 7 percent of the used glass cannot be reprocessed due to its size, structure or impurities. This material is processed into expanded glass granulate , for example . This lightweight filler is used in products in the dry mortar and construction chemicals industries, in acoustic panels, in solid wall construction materials and in the renovation of old buildings.
Process of recycling old glass for the production of new glass packaging
- Separation of iron parts with a magnetic separator
- Detection of larger foreign matter by hand
- Size reduction to 15 mm in the crusher
- Sieving on a perforated sieve channel, foreign matter that is lighter than glass is sucked off.
- Removal of opaque materials (e.g. ceramics) using optical processes
- Re-sorting by hand
- Detection of residual ferrous substances using a magnetic separator
- final check
- Melting down - re-pouring
Recycled white glass
Recycled green glass
Recycled amber glass
Recycled stained glass
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Glass recycling problems due to contamination
Glass products that do not belong in waste glass collection containers (so-called missed throws, for example laboratory glass, glass from oven doors, microwave ovens or heat-resistant glass that is often used in the lids of cookware) can sometimes neither be recognized by the human eye nor by optical devices. They get into the melt and can damage the machine and cause production stoppages. Glass types with additives, such as lead glass (glass containing lead oxide, so-called "lead crystal"), and normal drinking glasses are undesirable in the waste glass collection, as they change the glass composition in the long term, as they usually contain chemical additives to improve the optical properties, which are common for packaging glass are undesirable. Pieces of mirror glass are also very problematic .
Problems continue to cause problems with ceramics, stones and porcelain, which - broken into thousands of small pieces - cause glass defects and make the new glass packaging unusable.
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Benefits of glass recycling
For 1 m³ of primary raw material 7 m³ of rock have to be extracted. The use of used glass packaging reduces the need for primary raw materials and protects the natural area. Used glass packaging requires lower temperatures to melt and therefore less energy than the mixture of primary raw materials (quartz sand, lime, dolomite and soda). This also results in a reduction in CO 2 emissions.
- Glass recycling is ecologically more advantageous than new production, since the melting point of pure quartz is 1700 ° C and melting (refining) from fresh raw materials is therefore very energy-intensive.
- The melting down of single-type waste glass makes sense in any case, since 100% of the waste material goes into the product. Melting glass from raw materials would require up to 25% more energy.
Recycling code -70 (GL) for colorless glass
Recycling code 71 (GL) for green glass
Recycling code 72 (GL) for brown glass
Reuse or melt down?
The energy balance of returnable bottles is usually a lot better than that of melting (recycling). Which option is more sensible in terms of energy and ecology depends on many factors:
- Length of the transport route (whereby waste glass is initially cheaper to transport)
- Processing costs (such as sorting / cleaning / rinsing versus melting and reshaping)
- Refilling is only possible with standardized forms.
- (Costs for) energy sources such as natural gas, water and electricity
National
- Germany: Green Dot
- Austria: Austria Glas Recycling
- Switzerland: VetroSwiss
various
The Dutch entrepreneur and beer brewer Alfred Heineken developed the "WOBO" ( "world bottle", German "World-bottle"), a beer bottle with approximately rectangular cross section, for use with mortar filled should serve as a building material. The idea came to him when he in 1960 , the Caribbean island Curaçao visited and the beach littered with empty beer bottles found since resending would have come to the breweries for islanders too expensive. Heineken wanted to recycle the beer bottles and at the same time create an inexpensive building material for the island's impoverished lower classes. The idea did not get beyond the concept stage and the production of some sample bottles.
Movie
- How broken pieces become bottles. Documentary, Germany, 2017, 28:30 min., Script and direction: Stefan Radüg and Jennifer Kopka, production: Kamera Zwei, NDR , series: Wie geht das? , First broadcast: May 24, 2017 on NDR, table of contents by NDR, online video by NDR.
Web links
Individual evidence
- ↑ Deutsche Umwelthilfe , information sheet 9730-050
- ↑ European Glass Recycling: 2009 , European Container Glass Industry Association
- ↑ Hans Jebsen-Marwedel: Glass manufacturing defects. 4th edition. Pp. 214, 232 f.
- ↑ Sustainability report with 2007 environmental statement from Austria Glas Recycling GmbH
- ↑ Why recycle glass? Initiative of the glass recyclers in the glass packaging action forum in the Bundesverband Glasindustrie eV, accessed on January 6, 2012 .
- ↑ https://web.archive.org/web/20150226061930/http://www.glasaktuell.de/zahlen-fotos/recycling-zahlen/
- ↑ Stephan Dietrich: The recycling lie. In: Infosperber.ch . October 28, 2019, accessed November 18, 2019 .
- ↑ BMVBS ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Product information from the Bavarian Chamber of Architects on behalf of the Federal Ministry for Transport, Building and Urban Development
- ^ Website of the city of Gallen on glass recycling online (accessed on April 14, 2013).
- ↑ 2006 environmental statement from Austria Glas Recycling GmbH (pdf; 1.7 MB) ( Memento from March 31, 2010 in the Internet Archive )
- ↑ Stephan Dietrich: Altglas: Glass recycling has a bad ecological balance. In: observer.ch . July 12, 2019, accessed August 3, 2019 .
- ↑ Paul Petr Unia: The Heineken WOBO (World Bottle). In: archinect.com , September 26, 2007, (English)
