Glass is considered one of the most ecological materials on Earth. Few people know that, despite its fragility, glass is eternal: it can be recycled indefinitely without losing its properties! That is why, among other things, it is so important to pay attention to its proper segregation. In addition, glass containers can be cleverly used in many ways. Why else is glass eco-friendly?
The origin of glass
Glass is everywhere. It is an important element in every industry. In cities and beyond, in homes, schools, offices – glass appears at every turn. It has been known to people almost since the beginning of civilization, because the ingredients needed for its creation are – and always have been – easy to obtain.
To create glass, quartz sand – the most common sedimentary rock in the world – and high temperatures are needed. Depending on the desired properties, various chemical compounds are added, including metal oxides that affect its color. The process itself is not very complicated – yet glass packaging or dishes, unlike plastic ones, are still widely perceived as luxurious. Meanwhile, glass recycling allows it to be processed or – if undamaged – used indefinitely. That is why, among other things, a deposit is paid for some glass packaging in Poland, and for most in many different countries in the European Union. This is intended to encourage consumers to take care of bottles and return them for reuse.
Eternal glass
Glass recycling in Poland in 2018 was only 57%. In comparison, in Lithuania it was 74%, in Germany 85%, and in Belgium as much as 96%. This is all due to legal regulations, which in other countries introduce financial incentives for segregating glass packaging.
It is worth knowing that in Poland, in addition to bottles, jars and cosmetic packaging can also be thrown into the green glass container. They do not need to be washed – this is done at the waste disposal plant anyway. All these items can also be damaged.
If it goes into the bin and is not returned for a deposit, ecological glass is processed into so-called cullet. This, in turn, is melted down into a mass from which new dishes, packaging and bottles are made. After reuse, they can be broken again, melted down, and so on, without extracting new raw materials from nature!
Not all glass is eco-friendly. Ceramic dishes, light bulbs, spectacle lenses, heat-resistant dishes, or mirrors, among others, are not suitable for recycling. This is due to the addition of chemical compounds other than those used in its basic version, e.g., refining or changing its properties, and a different melting temperature of cullet made from these types of materials.
Glass recycling - process
To reuse eco-glass, it must first be sorted in a waste sorting plant. In the first step, people look for errors and mistakes in home recycling; in the second, the process is automated. The next stage is removing labels, glue, and dirt. Clean glass is mechanically separated by color, then broken and crushed into cullet. From this, metal impurities are often removed with magnets. Then, machines check the color and composition of the cullet several more times, separating valuable glass from that unsuitable for recycling.
Finally, the separated material goes to glassworks, which in their process allow the use of "foreign" cullet. There, the glass batch, along with the recycled cullet, is melted in a glass furnace at a temperature of approximately 1450°C, resulting in a homogeneous glass mass. After cooling to a temperature of approximately 1100-1200°C, desired products are formed from it, which are then subjected to the annealing process – i.e., cooling them under controlled conditions to room temperature – giving the glass appropriate strength.
It is worth checking – knowing now how glass recycling works – what is produced thanks to these processes. The second (or subsequent!) life of this material is not just about reusing it for packaging. Glass cullet can also be a raw material for the production of specialized glass – which then cannot be reprocessed – and can become an element of cleaning pastes, ceramic masses, grits, or insulating materials.
Recycling at Krosno Glass
And what does glass recycling look like in glassworks producing high-quality household products, such as Krosno Glass? First, it should be mentioned that here only "own" cullet is used, which is treated with the same care as raw materials in the technological process.
This is extremely important due to ensuring a stable chemical composition of the glass (unchanging forming parameters) and high requirements for the colorlessness of the glass. It is also essential that the circulation of glass waste is limited to one furnace, with great care for the cleanliness of the processing process. This allows for very good control of the production process and the elimination of various metallic impurities, such as iron entering with the cullet, which significantly impair the colorlessness of the glass.
Glass recycling at Krosno Glass takes place at several stages of product manufacturing. Successively during forming, trimming of the rim, annealing, cutting of caps, sorting, grinding of rims and bottoms, washing and drying, sealing of rims, decoration, and final quality control. A significant portion of the cullet comes from cut-off caps, which are a technological excess characteristic of glass product forming, but also from defective products.
During the transport of cullet, metallic impurities are removed from it using magnets placed along the conveyors. The thus purified waste goes to crushers, and then is stored in big-bags and boxes, separately for each furnace. This ensures the constancy of the chemical composition of the cullet, which allows for its controlled use in the production process.
Inspiring vessels
You don't need a glassworks to give glass a second life. Both glass vessels unsuitable for recycling, such as vases or bowls, and the simplest glass packaging can be used in many different ways in the household. They can become an originally arranged element of seasonal decoration, serve as candlesticks, broken pieces can go into pots on the terrace as a filtering layer, be painted, suspended, glued with other elements. Just use a little imagination or look for guides available online to get inspired and reuse something that seems no longer needed.
When buying products in glass, such as candles, it is worth paying attention to their design. When they lose their original purpose, simply remove the remnants of the product and wash them thoroughly to use them, for example, as a mini plant pot, office or bathroom organizer, or a tealight holder. Such solutions are ultimately beneficial not only from an ecological point of view, but also for the household budget!