Tyre recycling, an environmental and economic solution

Procellantas in Colombia will recycle all components in used tires by way of thermal microwave treatment, thus avoiding toxic smoke from the burning of such tires or the overflowing of these into sanitary fillings in cities – both of which represent an alarmingly growing environmental problem throughout the region. 

 

About five years ago, Diego Alberto Castaño put a slice of cheddar into the microwave oven in his house and thoughtfully observed how it first melted, and then flowed. In a few minutes he would be eating a plate of nachos with cheese, but in five years he would be developing a similar technology to recycle used tyres using microwaves. 

This innovative project, sponsored by GVEP International and implemented by the Colombian enterprise Procellantas led by Castaño, is the first of its kind in Latin America. It could hold the solution to the acute environmental problem generated by the thousands of used tyres in the region. “Tyre recycling via microwaves is now viable, in both economic and technological terms,” assures Castaño.

In Colombia alone there are 4.5 million tyres a year that usually end up in landfills. There, they are burnt – generating more than 150 toxic compounds that may be carcinogenic and that pollute groundwater below landfills.

Central and local governments in most Latin America countries have not found an effective solution to this problem of disused tyres, which also represent an overhead cost to the waste collection companies. 

The project waste to energy project proposal presented by Procellantas, was one of the winners of the IDEAS Energy Innovation Contest in 2009. This contest was launched by GVEP International, the Inter-American Development Bank (IDB), the German Development Cooperation (GIZ) and the South Korean government.

Procellantas’ project received financial support and monitoring from GVEP, and seeks to not only disintegrate the tyres in an environmentally friendly way, but also to take advantage of the waste generated in this process - called pyrolysis - which can be turned into five potentially profitable sub-products. 

Now, Procellantas has successfully completed its first phase. This has involved setting up a prototype plant, which has the ability to process one tyre at a time. This model validates the assumptions made during the design stage in the theoretical framework. The efficiency of the applied technology is being thoroughly checked, and corrections are being made to the designs for the next phases of project development: optimising the process variables to be used in the commercial operation, in order to reduce operative costs.

As for many of these awarded innovative projects in Latin America, the beginning has not been easy. The main problem has been, according to Castaño, “the lack of technological resources, technicians and materials available in Latin America.” In order to build the initial plant design, Procellantas had to import stainless steel 304. Then, they had to find both a nationally and internationally certified welder, who could carry out the welding. Finally, a vacuum pump, unavailable in Colombia, had to be imported from the U.S., this took three months. 

Fortunately, the pilot plant is now operating in Medellín. It consists of a special furnace, the reactor or microwave cavity - built in special stainless steel and perfectly sealed in order to withstand high temperatures - which is where the pieces of cut up tyre are introduced. During the pyrolysis process nitrogen must be injected so that the atmosphere remains inert, to avoid combustion, explosion or saturation of flammable gases, since the temperature rises to 500 degrees C. 

Gases that are produced are suctioned with a vacuum pump and expelled at high temperatures. These gaseous fuels pass through a heat exchanger, where some gases become lighter and others heavier. The heavy gases condense, becoming liquid. These liquids can be used with other applications such as boilers to generate power, steam or other industrial applications.

“With more funding available,” says a hopeful Castaño, “we could proceed with a micro distillation of this fuel and get to make diesel for cars.” Castaño also considers the possibility of generating his own energy to power his plant. For this, “we would have to ask permission from the Ministry of Energy and Mines of Colombia and that costs a lot of money.” Procellantas does not rule out this possibility, and is approaching and making some proposals to potential buyers.

Once the process of pyrolysis is complete, a black or carbonaceous residue is left behind. Castaño explains that “this residue can become activated carbon or carbon black or a mixture of both.”

The black residue or carbon black has more than 500 applications ranging from paint for cars to dyes or stains for leather and textiles. “This is the direction in which we are heading,” says Castaño, “because countries consume very high levels of carbon black.” And activated charcoal is important as it is used for white water and wastewater sanitation processes. Another residue from the pyrolysis process is the remaining steel, sold as scrap.

While conducting all of the preliminary research, Castaño found tyre-recycling projects in Canada and the U.S. that use the same technology, yet the costs are very high and therefore “it is a technology that is not available for us in Latin America.” 

In the U.S., where there are 50 million scrap tyres per year, Castaño found that the smaller microwave ovens disintegrate one thousand scrap tyres per day, where the investment has been around the 30 to 35 million U.S. dollars. 

“We are a very young venture but we are developing a very high quality product,” assures Castaño. Apart from the IDEAS 2009 Contest, Procellantas has won several other national level awards, including the Bavaria Destapa Futuro entrepreneurship contest. They have also been chosen by the province of Antioquia to form the macro energy project nationwide.

“We want the model offered by Procellantas to be a technology that is not only available and can be bought by developing countries, but also that those who use it can benefit from the products obtained from recycling,” said Castaño. 

Procellantas is testing the technology with this first prototype processing an approximately 9-kilo tyre. The idea is to eventually get to 300 tyres per day.