Sustainable Development Goals
PROJECT INFORMATION AT A GLANCE:
Project Status:
Controlled research reviewed; commercialization under evaluation.
Organizations Involved:
Confidential mineral-engineering research partner; Klean Industries
Services / Equipment:
rCB Carbon Upgrading, Design & Engineering, Feasibility Studies
Recovered carbon black is judged on numbers, and the number everyone watches most is the one that misleads them. Our engineers help write the ASTM standards that govern how recovered carbon black is tested and classified, and those standards are explicit that no single laboratory figure, least of all ash content, makes a good material. Performance in the finished compound does.
The minerals in recovered carbon black are not waste to strip out. Silica gives a tire its grip and zinc drives its cure, and both survive into the recovered black, where they keep reinforcing the rubber. Pull them out completely and you remove the very performance a compounder is paying for. Ash is a specification to balance, not a score to zero.
And the score can fall for a reason that makes the product worse. During pyrolysis, carbon released from the decomposing rubber re-deposits onto the recovered black, diluting the measured ash while coating the surface the rubber must bond to. The ash figure drops, and tensile strength and dispersion drop with it. Ordinary composition tests cannot tell the two carbons apart.
The Challenge
A lower ash reading is treated as a better product, and that assumption costs money. Commercial furnace carbon black carries little inorganic material, so reducing ash to close the gap looks sound. It breaks down in recovery: the minerals a tire carries do not simply disappear, and in many compounds they help the material reinforce. Removing them all makes the laboratory report look cleaner while the rubber performs worse.
There is a second trap hiding in the same number. The pyrolysis that recovers the carbon can also deposit fresh carbon onto its surface, adding solid mass that dilutes the measured ash without removing any mineral at all. The ash falls, the yield rises, and reinforcement declines, because the newly deposited carbon does not behave like the carbon black built into the tire.
The commercially relevant question is not how to drive ash down. It is which mineral profile each application needs, where selective reduction pays for itself, and when the separated mineral stream is worth recovering on its own. Zinc oxide is a vulcanization ingredient the rubber industry buys back, and silica is a reinforcing filler used in passenger and winter tires. Neither is automatically a saleable product, and neither should be chased at the expense of the carbon's own performance.
The Solution
Engineer the mineral profile to a specification, not a headline. The work starts from the compound: which rubber, which filler loading, which performance requirement. Ash content only matters in that context. A grade destined for one application may tolerate, or even want, minerals that a more demanding compound must reject.
Reduction is then made selective. Where an application needs a lower mineral load, we design the process to remove the right fraction while protecting the surface and particle characteristics that carry reinforcement. Where the mineral content is doing useful work, we leave it in place. There is no single treatment applied to every tonne, because every compound is different.
Treat the mineral stream as its own business. We assess whether a zinc-rich or silica-rich fraction can be concentrated, processed and qualified for a specific customer, rather than mistaking elements present in the ash for a finished zinc oxide or silica product. A secondary stream earns value only when a separation process and a qualified outlet work together, the same principle we apply recovering metals and minerals from waste-to-energy ash.
Controlled research reviewed for this development shows the mineral composition of a recovered carbon stream can be materially changed, and that surface and reinforcement can shift at the same time. That is a reason for care, not a licence to over-promise: the laboratory result has not been deployed as a commercial Klean plant, and process chemistry, counterparties and pilot arrangements remain confidential.
The Outcome
The mineral profile is a dial, not a defect. Adjusting it selectively opens the higher-value compounds a producer cannot currently serve, without surrendering the reinforcement the existing grades already deliver.
The mineral dimension introduces a potential second revenue stream. Zinc-derived products matter to the very industry that supplies the feedstock, and silica-derived products serve reinforcing and specialty formulations including passenger and winter tires. Their economic recovery, the purity that can be reached and their acceptance against customer specifications remain subjects for pilot testing, not claims of production today.
Roughly US$1,000 to US$1,500 per tonne describes the established rCB commercial reference in this programme, and our separate advanced-carbon studies have examined application-specific values for graphite and other engineered products through different conversion routes. A lower ash figure is not, by itself, a step up that ladder. The step up is a material that performs in its application and a co-product that earns a buyer.
Three priority lessons selected from the wider experience behind this project. Each highlights a decision that can materially influence technical performance or commercial viability. Through a defined engagement, we apply our broader technology and delivery experience to your project's requirements, risks and opportunities.
1. Ash is a specification, not a score to minimize. The minerals in recovered carbon black reinforce the rubber compound, so removing them all strips out the performance a compounder is paying for. Finishing must be set by the application, not by a universal purity target.
2. A falling ash number can hide a weakening product. Carbon re-deposited during pyrolysis dilutes the measured ash while degrading reinforcement, and conventional tests cannot tell the two carbons apart. Quality is proven in the finished compound, not the laboratory readout.
3. The mineral stream deserves its own assessment. Zinc- and silica-bearing material has real value in the right form, but an elemental assay is not a product specification. Recovery, purity and a qualified buyer decide whether a second revenue stream is real.
WHAT DO THESE LESSONS MEAN FOR YOUR PROJECT?
A producer already running recovered carbon black, or a developer building a new plant, should settle the mineral profile before locking in equipment, specifications and offtake. A process that blindly drives ash down quietly downgrades the material the plant was built to sell. We can structure a paid feedstock and market assessment, define the targeted pilot work and establish the preliminary economic and equipment basis.
Discuss Your Carbon Mineral Profile with Klean >> GO.
For equipment developments, our paid Detailed Equipment Quotation (DEQ) defines the preliminary technology and investment basis, followed where warranted by a Detailed Feasibility Study (DFS) and Front-End Engineering Design (FEED). Confidential specifications and proprietary process information are considered under an appropriate NDA and engagement.
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ABOUT THE INFORMATION PRESENTED
This case summarizes our review of controlled mineral-profile research and the product-development opportunity it opens for recovered carbon black. Process chemistry, sample provenance, confidential partner details and pilot arrangements remain restricted. The zinc- and silica-derived materials described are candidate co-products under evaluation, not products already recovered or sold at commercial scale.
This project addresses the United Nations Sustainable Development Goals (SDGs) by considering the goals and associated targets illustrated by the WBCSD's Tire Industry Project (TIP). TIP provides a framework for action that outlines impactful pathways for the tire sector to contribute to achieving the Sustainable Development Goals (SDGs). To learn more about how our approach, solutions, and technologies contribute to advancing the SDGs, please review the report “Sustainability Driven: Accelerating Impact with the Tire Sector SDG Roadmap”.
