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Glass Begets Glass - Recycling Glass

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by - 11/25/2015 3500 Views

Domestic Glass Waste Management

Recycling Glass is the process of transforming waste glass into usable products. Glass waste should be segregated only by chemical composition, and then, depending on the end use and local processing capabilities, might also have to be separated into different colors. Many recyclers collect different colors of glass separately since glass retains its color after recycling. The most common types used for consumer containers are colorless glass, green glass, and brown/amber glass. The process of recycling glass is very convenient because the composition of glass can be recycled without much of the fibers burnt or lost once a product is used.

Glass makes up a large component of household and industrial waste due to its weight and density. The glass component in municipal waste is usually made up of bottles, broken glassware, light bulbs and other items. Adding to this waste is the fact that many manual methods of creating glass objects have a defect rate of around forty percent. Glass recycling uses less energy than manufacturing glass from sand, lime and soda. Every metric ton (1,000 kg) of waste glass recycled into new items saves 315 kilograms (694 lb) of carbon dioxide from being released into the atmosphere during the creation of new glass. Glass that is crushed and ready to be remelted is referred to as CULLET.

Cullet, which is also termed as domestic glass scrap waste is easy to recycle. The UK currently recycles around 50% of container glass (like bottles and jars) and while this figure has doubled over the last five years it still lags behind other countries. For example, both Switzerland and Finland recycle more than 90% of their glass.

Glass can be collected in bottle banks or as part of your collection. However, there is still more we can all do, such as remembering to recycle our clear jars (pasta sauce jars and jam jars) which are often forgotten. The hotel business sector still has a lot of work to do to recycle glass – bars, restaurants and pubs currently throw away over 200,000 tonnes of glass every year into landfill.

The Recycling Process:

Firstly, glass scrap is collected and taken to be reprocessed, then crushed and thoroughly cleaned so that contaminants are completely removed (mechanised colour sorting is usually undertaken at this stage if required). It is then mixed with the raw materials to colour and/or enhance properties as necessary, melted in a furnace, moulded or blown into new bottles or jars.  

Recycling & Environment:

Let’s see what positive or negative impact is there on the environment. The production and use of glass has a number of positive impacts; new glass is made from four main ingredients: sand, soda ash, limestone and other additives for colour or special treatments. Although there is no shortage of these raw materials as yet, they all have to be quarried, which can damage the landscape, affect the environment and use more energy.

It is very important to note that, Glass is 100% recyclable and can be endlessly reprocessed with no loss of quality.  Therefore by simply recycling our glass we can conserve non-renewable fossil fuels &reduce the emission of harmful gasses into the atmosphere.

When Cullet is put into a furnace in the glass manufacturing process, it substantially reduces the energy requirement and decreases CO2 emissions. Each tonne of cullet added to the furnace saves 1.2 tonnes of raw materials – decreasing emissions still further.

Recycled glass can be used to make a wide range of everyday products and some that are completely unexpected, including: new bottles and jars, glass wool insulation for homes, which also helps with energy efficiency.

The manufacturing of new glass takes a lot of energy to make, first in transporting the materials to the furnace and then to heat them to a high temperature. An efficient furnace burns 4 gigajoules (GJ) (unit of energy measuring heat) to melt every tonne of glass – that's the energy equivalent of burning 250kg of wood.

The Challenges:

Cullet use, however, is not free from disadvantages such as the following:

  • Metallic impurities, such as bottle caps or foil from wine bottles, can cause significant refractory damage and shorten furnace life;
  • Presence of ceramic will lead to quality problems and will result in rejects;
  • At high cullet levels, composition and therefore the physical characteristics will be hard to control, potentially causing quality problems;
  • Organic content in cullet may lead to color and refining difficulties;
  • Presence of aluminum in cullet may significantly reduce mechanical strength of end products;
  • Impurities may give rise to undesired air emissions.

 

The main problem with glass recycling is the quality of the glass collected. It can be contaminated, and therefore difficult to use in glass containers again. Due to the relatively low value of the material and the required processing costs, much glass ends up in aggregate where there is no environmental benefit. To try to counter this, a split target has been put in place to limit the amount of glass that doesn't go through a remelting process.

The different types of glass

We use many different types of glass, but at home we mostly use 'soda-lime-silica' glass for containers like bottles and jars. It is important not to mix up the different types of glass as they are re-processed differently.

Borosilicate glass – used for heat-resistant cooking equipment like Pyrex

Lead glass – for sparkling decorative glassware

Glass fibre – is used for insulation and fibre optic cable.

These different types of glass are not widely recycled so do not add these into your collection container or bottle banks at the recycling centre.

Colour and quality:

During the glass manufacturing process, extra raw materials can be added to give the glass a particular colour or special qualities. The extra raw materials that can be added are:

Iron for a brown or green colour

Cobalt for blue

Alumina for durability

Boron, to improve resistance to heat or cold.

Category : Glass

Tags : Glass Scrap, Glass Cullet, Glass Scrap Recycling, Glass Scrap Current Trend, Glass Scrap Waste


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About Georgy Abraham

As the bright morning of 28th May dawned in the year 1972, in the fulfillment of time according to the plan & will of Almighty Godbrought me forth into this world and I was brought up & educated in Orissa. My parents provided me with the best of education in an English medium school with high standa .... more info

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