Rubber is a general term that defines rubber polymers from gum. It may be of natural or synthetic origin, which is obtained from isoprene. The latter is a more pure, homogeneous form and the cost of obtaining it is lower than that of natural rubber.
The main use of synthetic rubber is to replace natural rubber which is obtained from resin latex produced by the rubber tree, Hevea Brasiliense.
The first production of synthetic rubber, profitable from an economic point of view, was SBR rubber, produced in 1929 by Walter Bock’s emulsion polymerization method from 1,3-Butadiene and styrene. In 1930 Erich Konrad and Eduard Tschunkur managed to produce NBR rubber in Germany, while in the USA Dupont produced CR rubber, which is today called neoprene.
Between 65% and 70% of the total rubber production is used as raw material for the production of machinery casings. Natural rubber is used as a polymer or as a mixture with synthetic rubber. The disadvantage of natural rubber is its liability to break down if it comes in contact with sunlight, UV light, or glue. Another important reliance is its use as a binder in the paper industry, the carpet manufacturing industry, or in medicine for latex gloves. It can also be used as seal elastic profiles; for those elements that are subject to the outside action EPDM (ethylene-propylene monomer) is used.
In 1942, the production of silicon rubber was successful in the USA, which was followed in 1948 by the fluorine rubber, so that the production of synthetic rubber was improved in the coming years.
More than a billion tires end up being worn out every year. As an incursion in history, the recycling of tires has always been an important process, a priority for humans’ well-being, but also for maintaining the economy. Half a kilo of rubber equals the value of a half kilo of silver. Tires are a category of waste that we encounter all over the environment and are also some of the most reusable waste, made of very durable rubber.
The continued development of the use of rubber products in all areas and thus of the rubber processing industry requires the recycling of elastomers, from out-of-use vulcanized products, such as tires, air chambers, and technical articles.
The main directions to value waste products and rubber waste, grouped in descending order of technical efficiency process are:
- The reuse of waste rubber products in the same quality as the initial product, by repairing and retreading it;
- The reuse in other rubber products;
- The recycling as a material to be returned to elastomer compositions as a powder or vulcanized rubber powder;
- The use as a source of various raw materials such as black carbon or oils obtained by pyrolysis;
- The use as fuel for obtaining heat, cement, or steel;
- The reuse as modifying agents for various materials, used in particular in the field of road construction.
Among rubber products, tires are by far the largest, which explains the focus on reintroducing used tires into the economic cycle while avoiding pollution. As worldwide tire production totals over 800 million annually, the potential for recycling millions of old tires is clearly very important.
The process of vulcanization makes it possible to produce high-quality tires which are very strong and resistant to wear and, in technical terms, through cross-links of hydrocarbons chains that form the rubber, lead to the creation of a three-dimensional elastic network.
The resulting sulfides cannot be removed, and the attempts to modify their structure by vulcanization have proven to be difficult, costly, and energy-intensive. Research and development have continued and so many techniques have emerged which promise to increase the share of recyclable material that can be used in the production of new tires. A tire consists of:
- synthetic rubber
- natural rubber
- sulfur and sulfur compounds
- oils: aromatic, naphthenic, paraffinic
- fibers: polyester, nylon
- dyes: zinc oxide, titanium dioxide
- fatty acids
- inert materials
- carbon black.
The elasticity of the tire’s casing, which is very important in terms of its efficient use on the vehicle, presents difficulties for the mechanical process to be used in separating steel and textile fabrics from rubber.
Worn tires, after having reached their service life, depending on the wear condition, can be most effectively recovered by repair and retreading processes. Since all worn tires are not retreadable and the number of possible retreads is very limited by size (1 to 3 retreads), in the end, all tires produced fall within the category of retreaded tires.
For worn textile-insert tires, there is the possibility of recovery by transforming them into regenerated rubber and re-using it in elastomer compositions. The problem of using metallic heart tires, which are non-repairable and non-recoverable, cannot be solved at present, nor can there be a single, generally accepted solution for expansion, with technical and economic advantages worldwide.
However, various recovery processes have been adopted in the world, including grinding (ambient, cryogenic or wet) transforming in powder, pyrolysis, heat transformation, use in the metallurgical industry.
Why are used tires recycled?
Here are the reasons why you should recycle used tires and the benefits of this process:
- You contribute to the reduction of waste;
- You contribute to the production of chemicals with energy potential, that are found in used tires;
- The processing of used tires contributes to the emergence of new and necessary products, for example, the artificial grass;
- New jobs are generated through the recycling of waste, thus developing a healthy economy;
- The recycling of used tires prevents air pollution – carbon is one of the components of the rubber and by combustion (as it often happens with used tires) contributes to increased space pollution;
- Combined with carbon emissions, worn tires can cause fires that are difficult to control;
- Used tires take up a lot of space when we choose to store them;
- Tires are not biodegradable, so they will not easily disappear from the Globe, contributing to waste in natural areas like forests and oceans.
How are car tires recycled?
For the recycling of used tires, it is important to know that they are not subject to the waste collection phase because they are far too bulky. Disposal of this waste is also banned by legislation, so economic operators try to reuse or recycle it. However, the units that sell tires are legally obliged to accept used tires: the manufacturer, car services, and vulcanizations.
It is important that we do not burn tires because we can cause fires that cannot be extinguished, but also do not throw them into forests or lakes, so you won’t contribute to the general deposition of the mass of natural waste.
We can talk about two large categories of rubber recycling:
- material — when the granulation phase stops at a larger size so that the resulting product can be used for lawns, constructions, or roads;
- thermal — when the product becomes powder and has other uses and its energy content is also recovered.
What is the process of tire recycling?
The legislation prohibits the disposal of tires at dumps, and economic operators are trying to recycle them through an apparently complicated process, but with multiple benefits for the environment and the air that we breathe. Here is the car tire recycling process:
- separation by air pressure
A mechanical procedure then takes place whereby the components with a high purity are separated, and this procedure is also divided into several phases:
- cutting the beads – at this stage of tire recycling the metal ring is removed from the bead;
- shredding – worn tires are finely chopped and crumbled until small pieces of material are obtained;
- granulation — the main stage, through which the fine granules obtained are used for the production of rubber mats, paving, tiles, street furniture, synthetic lawn;
- blade grinding – the final phase in which the rubber is turned into rubber dust.
What are the tire recycling systems and standards?
The recycling of used tires consists of three types of systems that manage the flow of used tires:
- Extended producer responsibility scheme – manufacturers are obliged to manage the tires that are no longer used;
- Taxing scheme – The State assumes its part of responsibility concerning used tires through a tax included in the tire’s cost;
- The free market system – is based on voluntary cooperation between companies.
What you should do before collecting worn tires?
Worn tires can be fully recycled, and their collecting is influenced by no external factor: tire sellers will take any type of used tire, regardless of whether it was bought from them or not. According to the legislation of 2004, once the tire becomes waste, it is no longer dependent on the brand, but on its quantity. The first step toward a healthy environment and economy is to prolong the life of tires, by properly caring for them and complying with the required standards.
How is recycled rubber used?
A noble and sought-after material, once re-processed, the rubber is used in a number of valuable uses, including:
- construction industry – tiles, acoustic barriers, impermeable membranes;
- landscape – navigating bridge, porous pipelines;
- industrial seals and fillings;
- civil engineering;
- sports construction – athletics runways, tennis courts;
- carpet base;
- waste disposal;
- fuel in cement kilns;
- transport – vehicle parts, rubberized asphalt.
How are tires affecting the environment? What does the rubber recycling process involve?
Although tires are extremely useful to people, inadequate disposal has a number of negative environmental impacts. These are:
Hazardous pollution – used tires contain heavy metals and hazardous substances, which once infiltrated into soil or water cause mutations or animal and plant diseases.
Landfill congestion – used tires occupy a considerable space in landfills or other waste disposal facilities. The authorities require the storage, recycling, and disposal of used tires to be done by authorized firms with controlled environments.
Fire hazard – improperly destroyed tires increase the risk of fire. Used tires are also a fuel that keeps fire, which makes it harder to control and/or stop fires.
The challenge of a threat to the environment and public health – worn-out tires pose a risk of being a shelter for pests, which increase the risk of disease.
Prevention of harmful diseases
Old tires thrown in backyards, empty fields, and river beds are not just an unpleasant view but serve as a favorable environment for rodents, insects, or parasites that can transmit diseases.
Like most unused structures, such as abandoned vehicles, worn tires represent the optimum environment for rodents. They carry many diseases that can be transmitted to people.
Rodents’ urine, for example, can cause leptospirosis or Weil disease. This condition may lead to:
- meningitis (life-threatening),
- renal failure;
- affecting liver functions.
Salmonellosis is another disease that may be transmitted to humans by rodents, especially when a person comes into contact with excrements or feces of rats or mice. Other diseases that can be transmitted from rodents to humans are rat-bite fever and Rickettsia.
Why choose to recycle old tires?
It comes as an innovative solution anchored in simplicity and clarity. It is a simple recycling process, in the hope that this will motivate as many people as possible to do so.
The benefits of the rubber recycling process, creating new products, preventing the spread of disease, creating jobs, etc., are essential in ensuring the sustainability of the planet. Understanding the importance of rubber recycling is the main reason why massive efforts are being made to mitigate and prevent the negative effects of improper disposal.
If you carry out activities involving the generation or possession of tire waste or rubber waste, there are companies that offer you a wide range of environmental services, from take-over to recovery/disposal.