AKRON—Recovered carbon black has the potential to become a major material supplying the tire manufacturing industry, according to William Cole, director of product management at Natchez, Miss.-based Delta-Energy Group L.L.C.
But there are barriers and hurdles potential rCB suppliers face in providing commercial amounts of the material, Cole told his audience at the International Tire Exhibition & Conference in Akron Sept. 11-13.
With every major tire and auto company moving quickly toward corporate sustainability, the demand for recycled and recovered products is burgeoning, according to Cole.
"You have a lot of stakeholders who want action toward sustainability," Cole said. Both consumers and tire makers' auto industry customers want a more sustainable tire industry, he said.
"Customers want to reduce their carbon footprints, and environmentalists are keeping tabs on sustainability efforts," he said.
The ultimate goal is to make new tires out of recycled tires, according to Cole. But a tire's very durability makes it difficult to recycle, he said.
Fine rubber powders are one of the solutions, but their application is limited, according to Cole.
"There is no chemistry in fine rubber crumb," he said. "The smaller the particle, the better the performance. But still the rubber is in the same state it was when it came out of the mold."
Devulcanization means the rubber is surface-treated to sever sulfur crosslinks and make the rubber more malleable, according to Cole. There also is depolymerization through decomposition, which means recovering the constituent parts of scrap rubber through decomposition, he said.
"With depolymerization, there is no compatibility issue any more with polymers," he said. "But is it really a pipe dream?"
When depolymerization—at first called pyrolysis—began, the original goal was to create liquid fuel, according to Cole.
"The big issue was the production of char, a non-reinforcing byproduct," he said. "Char was 35 percent of the yield from pyrolysis, and when you have no home for 35 percent of the product, you know what happens economically.
"Some pyrolysis companies tried to sell their char as carbon black," Cole said. "This created a bad legacy—a legacy the current rCB industry has to overcome."
On the other hand, rCB is highly useful as a reinforcing material, according to Cole. Its usefulness has been proved in many technical demonstrations, and several rubber companies are already using it in commercial applications, he said.
The current problem with rCB is that demand outstrips supply. "Companies tell rCB makers, 'When you get full up and running, we'll start buying,' " he said. But while the demand is there, so are many barriers and hurdles to would-be rCB manufacturers.
"It is a difficult technology to master, and there are very high research and development costs," Cole said. "You must develop a chemical business culture that includes process control, product quality assurance and environmental compliance, among other things."
Besides high R&D costs, rCB production entails high capital costs to achieve a commercially sustainable production volume, according to Cole.
"This is a high risk if the technology isn't adequately demonstrated," he said.
Customer qualification time can last anywhere from six months to five years, but Cole said it is usually three years or more. That period is growing shorter as rCB gains industry acceptance.
Founded in 2001, Delta-Energy dismantled its existing rCB plant in Berthold, N.D., in 2015 and moved the equipment to the old International Paper facility in Natchez, according to the company website.
In 2017, Stamford, Conn.-based Castleton Commodities International L.L.C. acquired a majority interest in Delta-Energy, with Bridgestone Americas, a major investor in Delta-Energy, as an active minority investor.
At the time, Delta-Energy said the Natchez plant would process 100 tons of scrap tires annually to produce 11,000 tons of rCB. The Natchez plant will become fully operational by the first quarter of 2019, according to Cole.
Meanwhile, in 2017 ASTM created Committee D36 to devise industry standards for rCB. There are two subcommittees, Cole said: D36.10, responsible for writing standards and test protocols for rCB, and D36.20, charged with writing standards and test methods for the co-products of rubber decomposition.
Until the standards are fully developed, there are plenty of questions tire and rubber product manufacturers can ask rCB producers about the quality of their products, according to Cole.