Danish manufacturer of tyre recycling equipment, ELDAN Recycling A/S, has developed a new sensor-based system to detect foreign objects in tyre shreds and reduce the risk of breakdowns and yearly down time.Read more
What is rubber recycling?
Rubber recycling refers to processing irreparably damaged or worn-down (natural or synthetic) rubber products for new use to prevent rubber waste from ending up in a landfill.
The process of reclaiming and repurposing rubber requires less energy compared to producing new rubber (puts less pressure on natural rubber, conserves space in landfills, and reduces environmental pollution).
Table of content:
- Is rubber recyclable?
- Rubber recycling industry introduction
- Rubber recycling challenges
- Rubber recycling process
- Rubber recycling innovations
- Rubber recycling news
Is rubber recyclable?
Yes, all rubber is recyclable but not all rubber is recycled. This is either because individuals or companies do not bring rubber to collection stations, or because not all authorities accept rubber. This could lead to rubber ending up in landfills. Maintaining the characteristics of the rubber can pose a challenge when recycling.
Rubber recycling industry
Most rubber for the rubber recycling industry comes from waste tires. The rubber recycling industry turns waste rubber products into usable material, that can be applied to make new rubber products. Waste rubber can also be turned into fuel.
Waste rubber is a hard product to recycle due to:
- The durability of the material,
- The large volume of waste rubber,
- The hazards that are involved with handling and storage of waste rubber.
Until recently, the technology to deal with waste rubber did not exist. Rubber stockpiles were the standard, despite the (economic, health, and flammability) risks and hazards.
Fortunately, decades of coordinated effort have resulted in effective and efficient rubber recycling programs.
Also, newer technologies such as pyrolysis and devulcanization have made recycling of waste rubber easier.
Recycling rubber presents challenges
Rubber is used in a variety of products, from tires on vehicles to disposable surgical gloves. Increasingly both manufacturers and legislators are realizing that rubber recycling is crucial for environmental sustainability. Rubber recycling can also improve the cost of manufacture.
The large volume of rubber waste produced globally makes it difficult to manage as accumulated waste rubber, especially in the form of waste tires, can pose a significant fire risk. Recycling rubber not only prevents this problem but can produce new materials with desirable properties that virgin rubbers don’t have.
However, recycling rubber presents challenges. The main challenge is to maintain the characteristics of rubber during the devulcanization process, which involves high heat and toxic chemicals.
Rubber recycling process
There is a complete industry dedicated to the rubber recycling process.
In the typical rubber recycling process, rubber is collected, shredded, sorted, and finally devulcanized to transform waste rubber into raw material.
Collection of rubber waste
Rubber waste is collected from deposits by individual households and from landfills whereafter it’s sent to recycling centers. In most cases, this rubber waste is in the form of a waste tire (ELT), the major rubber product.
Size reduction of rubber waste
To reduce rubber products into smaller particles a shredder/granulator is often the machine of choice. Reducing the size of rubber into smaller particles allows for easier processing during the sorting and devulcanization processes.
Click here for manufacturers of shredders for this application.
Rough crumb rubber is more manageable than whole waste tires but is not very useful. The rough crumb rubber still contains fragments of reinforcing fabric and wire.
Depending on the end market, additional processing may be necessary to remove those impurities and create a finer crumb size, or mesh.
Sorting of rubber waste
Sorting of rubber waste often occurs during the size reduction process. During this sorting process, steel fibers are removed from the rubber waste stream by means of a magnet.
Textile fibers are separated from the waste stream by using (shaking) screens, (wind) sifters, (low vacuum) suction equipment.
Devulcanization of rubber waste
Devulcanization of rubber waste is a process that reverses the “vulcanization” of rubber, recycling it so that it can be vulcanized again. This process converts waste rubber into a new “virgin” raw material.
Definition Devulcanization: A process that causes the selective breakup of the sulfur-sulfur (S-S) and carbon-sulfur (C-S) chemical bonds without breaking the backbone network and without degrading the material.
The devulcanized rubber can be mixed with virgin rubber or with other kinds of matrices to give new compounds without generating a significant decrease in mechanical and physical properties.
Many devulcanization process types are presented: chemical, microwave, ultrasound, thermomechanical, etc.
Other waste rubber processes:
Beyond this, there are other options for the processing of the waste rubber. They include:
This concerns the freezing of the waste rubber to process its recycling. While this process is less common, it’s still as effective as devulcanization. In this process, the rubber gets frozen with the use of liquid nitrogen.
After the rubber is frozen, it gets processed in mills where it is grounded to create granules. These granules then become suitable to create new rubber products.
Pyrolysis of rubber waste
Pyrolysis of rubber waste offers an economically and environmentally beneficial method for transforming waste rubber into useful products, heat, and electrical energy.
Pyrolysis is a recycling method that involves heating (thermal decomposition) whole or shredded waste rubber in an oxygen-free reactor to break the polymers down into molecules.
These molecules vaporize into gases that travel from the reactor to a condensing system where the gas transforms into liquid oil.
Non-liquified gases return to the combustion system as fuel. The liquid oil collected by pyrolyzing rubber waste is often required for processes in the metal, alloy, or chemical industry.
Innovations in rubber recycling
Innovations in rubber recycling have increased the quality of materials produced through rubber recycling processes. These rubber recycling innovations have also reduced the need for chemicals used in the rubber recycling process.
Innovations continue to be of significant importance as the need for new sustainable, circular end-use markets.
Recent innovations include the innovative use recycled rubber into rubber pavement that repairs itself when it rains.
Another recent innovation by EcoTech converts shredded rubber from used tyres into an ultra-fine rubber powder that is filtered to remove impurities and then re-formed into rubber sheets.
Rubber recycling news
Rubber recycling news and rubber processing news provides in-depth coverage of actionable examples of how rubber recycling professionals process irreparably or worn-down rubber products into reusable rubber materials.
Rubber recycling news and information topics include updates on product and equipment manufacturing, legislative news, original research, and material innovations.
Rubber recycling industry news gives recycling professionals a competitive advantage in the complex and ever-changing rubber recycling market.
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