CHEMICALS

Process technologies for tomorrow.

PROCESS SYTEMS FOR RECOVERED CARBON BLACK

The Hosokawa Group has developed a process for the sustainable recovery of Carbon Black from used car tyres. By performing a number of steps after pyrolysis, the process results in dust-free granular material that can be dosed accurately. It is ready for immediate use in the manufacture of new car tyres or other rubber-based products.

Many recycling companies that handle car tyres are keen to find a way to recover Carbon Black from the rubber. This 'black gold' must undergo several processing steps after pyrolysis before it can be used as recovered Carbon Black (rCB). "We've developed an efficient and sustainable process for that," says Marc Jacobs, Team Manager Chemicals, Minerals & Metals (CMM) at Hosokawa Micron in Doetinchem, the Netherlands. "Our new processing line makes it easy for recycling companies to recover top-quality Carbon Black from car tyres. Manufacturers of car tyres and other rubber-based products can then immediately use the resulting granules in their production processes."

Integral process

Hosokawa Group developed the new, integral process by combining knowledge, experience and equipment from a number of its subsidiaries around the world. "In particular, this project involved Hosokawa Alpine, Hosokawa Micron and Hosokawa Solids Solutions," continues Jacobs. "We also worked in close collaboration with a number of partners to ensure that our customers – the recycling companies – can depend on an efficient processing line in which all the machinery and systems are optimally aligned. Moreover, this 'one-stop shop' approach means that each customer has a single point of contact."

Recovered Carbon Black finishing process

rCB finishing

"Thanks to our expertise, we're able to produce rCB with precisely the properties that car tyre manufacturers are looking for. They require dust-free and free-flowing granular material that is easy to dose," he adds. In the preparatory process, the used tyres are shredded and ground, and the steel content is reduced as much as possible. The material then undergoes pyrolysis. The oil and gas produced in this process is reused elsewhere, and the remaining material forms the basis for Hosokawa Group's rCB finishing process. However, the particle structure of the rCB pellets must be altered in order for them to be used successfully.

Grinding

The pyrolized material is transformed into top-quality rCB granules in three consecutive steps: fine grinding, agglomeration and drying. The first step – fine grinding – is one of Hosokawa Alpine's specializations. The fine grinding step can be performed by two different grinding technologies: either with the Fluidized Bed Opposed Jet Mill TDG or the Mechanical Classifier Mill ACM.

TDG Jet Mills offer end product fineness in the range of d99 = 5-15 microns and coarser if required, even at high throughput rates. The TDG process also ensures the easy removal of impurities like metal wires during the grinding process. The ACM is limited regarding ultra-fine end product qualities. We recommend the ACM for coarser types at d97 = 20-40 microns. But the decision for a certain milling technology also depends on the product abrasiveness. For rCB types with a high ash content, the TDG solution has clear advantages in terms of OPEX.

Fluidized Bed Opposed Jet Mill TDG for recovered Carbon BlackMechanical Classifier Mill ACM for recovered Carbon Black

Handling

It is not unusual for grinding lines to have a capacity of 1 ton/hour or more. Bearing in mind that the bulk density of the ground product is approximately 80-120 grams per litre, the process can soon involve volumes of more than 10 m³/hour. At this stage, the Carbon Black is a dusty material with poor flow properties and a tendency to settle. "As a result, special expertise is required for handling and interim storage," explains Jacobs. "That expertise comes from our sister company Hosokawa Solids Solutions, which supplies the systems for trouble-free transfer of the semi-finished material between the various process steps."

Agglomeration

Next, the ground Carbon Black is agglomerated and then dried: two disciplines in which Hosokawa Micron excels. The agglomeration step can be performed using the Flexomix vertical high-speed mixer. The rCB is dosed into the Flexomix together with precisely the right amount of a binder (usually water). The moistened granules emerge at the bottom of the machine. The flexible wall of the mixing chamber is continuously massaged on the outside to prevent the product from sticking to the inside.

Flexomix vertical high-speed mixer for recovered Carbon Black

"Alternatively, it's possible to agglomerate the product using a Pin Mixer. This is a horizontal high shear mixer from one of our partners, the American company Mars Mineral. The pins on the central rotor shaft create a helix that transports the product at the same time. With the right amount of binder, the Pin Mixer is able to produce strong, dense, spherical particles which can be transported pneumatically without cracking. Both the Flexomix and the Pin Mixer operate as continuous processes."

Mars Mineral Pin Mixer for recovered Carbon Black

Drying

The resulting granular material is dried in a Hosokawa Micron static fluid-bed dryer (with or without a vibrating or shaking system) that has been specially designed for drying rCB granules. It is positioned directly under the mixer. Hot drying air is blown upwards through the holes of the perforated plate, evenly distributing the granules. Thanks to the slight incline, the product gradually moves into the cooling zone. After being sieved as a final check, the rCB is stored or packaged.

"Our interdisciplinary approach has resulted in an integral processing line to produce a free-flowing, dust-free granular material with the right properties in terms of particle structure," concludes Jacobs. "This solves a problem for recycling companies and means that the rCB granules are immediately ready for use by tyre manufacturers in the production of new tyres."

Carbon Black as a circular raw material

Car tyre manufacturers are keen to improve the sustainability of their production processes, including by stimulating the circular use of raw materials. By using recovered Carbon Black (rCB), tyre manufacturers can reduce their need for virgin material, which is produced by the partial combustion of hydrocarbons into soot. The production of rCB is significantly better for the environment since it does not involve the combustion of fossil fuels.

Hosokawa process technologies support the shift to more sustainable production methods, in addition to helping companies tap into opportunities for producing high-quality recovered Carbon Black as part of their own contribution towards their sustainability goals.

TESTING & PROCESS DEVELOPMENT

Test Centre in Doetinchem, the Netherlands Test Centre in Doetinchem, the Netherlands

Our test and process development centre in the Netherlands offers unique possibilities for testing your product to determine the most efficient process, system or plant prior to final design. We can provide laboratory-level as well as production-sized trials.

Whether you wish to test a single machine or a complete powder processing system, the same skilled and experienced staff are here to help ensure that your requirements are met, and that you are entirely satisfied with the results. Our principle is to deliver high performance yet affordable solutions that meet our customers' demands and long term challenges.

We also have rental equipment available for batch drying.

HOW CAN WE HELP YOU?

To learn more about our powder processing equipment and systems for recovered carbon black, contact us:

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