Recycled Rubber: Why should we recycle and what is the process?
At Greatmats, many of our rubber flooring products are made directly from the rubber reclaimed from automobile tires. Rubber recovery can be a difficult process but there are many reasons that we feel rubber should be reclaimed or recovered for use in rubber floors as well as a number of other products. Since the vast majority of rubber exists in the form of tires for vehicles, the recycling process tends to focus on those. First, a quick list of reasons why recycling rubber is a good idea:
- It is far less expensive than natural or synthetic rubber. Often, it costs less than half as much to recycle rubber than to produce virgin rubber.
- Some properties of recovered rubber are actually better for some applications than virgin rubber. This is one reason you will often find rubber rolls and rubber floor tiles made of reclaimed rubber.
- Making reclaimed or recycled rubber uses less energy than is required to make virgin rubber.
- It is an excellent way to get rid of used rubber products which can be difficult. Rubber rolls from these products can be used in a number of different applications.
- Many useful products, including rubber flooring and various rolls of rubber are manufactured by using materials from rubber tires and other recycled rubber products.
- Tires provide substantial amounts of power in incineration. Some cement factories in Australia, for example, use used tires as a fuel source.
Yet, even with all the advantages that come with recycling rubber, a vast number of used tires are being wasted around the world. In some countries, an enormous amount of used rubber is buried in landfills when it could easily be reclamated for use in products such as rubber rolls or rubber floor tiles. Perhaps surprisingly, many of the more responsible countries in terms of rubber recycling are developing nations. In Pakistan, for example, tires are collected and cut into pieces. The beads are removed and the rubber is burned to expose the steel. The treads and sidewall are pulled apart with the treads then cut into strips. These strips are used to cover the wheels of donkey carts and the sidewalls are used for items such as shoe soles and slippers.
Damaged tires are repaired in more cases than not. Tubes can be patched and tires can be given new life. One process that is frequently used in developing countries is called re-grooving or retreading. This process is used more frequently in places where regulations are less stringent and the standards are not as high. (Speed limits are also set lower so the dangers of using re-grooved tires is decreased.) The use of retread tires saves energy. Where a new tire needs 23L of crude oil for raw materials and 9L for process energy, re-grooving tires only requires 7L and 2L respectively. While passenger vehicles can usually only be retreaded once, truck and bus tires can often be retreaded up to six times. The process is fairly simple. The remaining tread of a tire is removed and turned into tire crumb. A new tread is then vulcanized (see our content page on Vulcanization) onto the remaining shell of the tire.
Of course, using old tires whole is another cost effective and environmentally friendly option for recycling. Tires can be used as tree guards, for erosion control, used in artificial reefs, fences, or as garden decorations. In some countries, wells are lined with old tires. Docks are lined with tires to act as “bumpers” or shock absorbers.
Another way rubber tires are recycled is by reducing them to their granular form and reprocessing the rubber from there. This is a costly process and requires a manufacturer willing to purchase the granules. Crumb rubber from retreading can be used in this way because it is a high quality rubber. Rubber manufactured by this process is often used in lower grade products like floor mats for cars, shoe soles, or as asphalt in road construction.
Still another way to salvage rubber is done in the chemical and thermal process. This type of recycling requires higher tech, more sophisticated equipment. With this process, the waste rubber is treated with chemicals and then processed mechanically. This can be done in a number of different ways:
- Acid reclamation – uses hot sulfuric acid to destroy the fabric of the tire
It also uses a heat treatment to make the scrap rubber more “plastic”. This allows its use as a filler with batches of crude rubber. This process also results in that strong “rubber smell” associated with some products. It is critical when choosing a rubber product (such as rubber flooring for a room you’ll be spending time in) that you consider the odor before buying it.
- Alkali recovery - Reclaimed rubber, treated by heating with alkali for 12 to 30 hours, can be used as a mix with crude rubber to lower the price of the finished article. The amounts of reclaimed rubber that are used depend on the quality of the article to be manufactured.
- Pyrolysis - This involves heating the tire waste in a vacuum with no oxygen which causes decomposition into gases and constituent parts. It is a technology which is still relatively new to the tire-reprocessing field.
The least desirable destination for tires is landfill. The landfill disposal of tires, if properly managed, is not necessarily an environmental problem. However, concerns about conserving resources and energy have brought about an increasing opposition to landfilling. Also, public sanitation and municipal waste management is often ineffective in developing countries and scrap tires are often found littering the streets which can have negative consequences for the environment.