In the recycling and processing of waste tyres, the pyrolytic carbon black grinding and granulation process plays a crucial role. With the increasing emphasis on environmental protection and resource recycling, pyrolytic carbon black is not only widely applied in the rubber industry. It also holds significant economic and environmental value. This article will provide a detailed analysis of the pyrolytic carbon black grinding and granulation process. You will understand how this process improves product quality and stability while enabling efficient, continuous production.
1. High-Temperature Pyrolysis
Process Principle
Waste tyres undergo pyrolysis at high temperatures ranging from 280°C to 350°C in a low-oxygen environment. In tyre pyrolysis plant, the main components of the waste tyres, such as natural rubber, synthetic rubber, carbon black, and vulcanizing agents, produce the following key products:
- Carbon Black: A black solid material formed from the carbon black and other inorganic substances (such as fillers, vulcanizing agents, etc.) in the tyres through the pyrolysis reaction.
- Pyrolysis Oil: Produced from the organic components in the tyre, such as rubber molecules and plastic components, it mainly consists of petroleum-based compounds, which can be used as fuel or further refined.
- Syngas: Composed of hydrogen, carbon monoxide, and small amounts of carbon dioxide and methane, which can be used for energy recovery.
Core Process
- Minimize the contact time between carbon black and oil gases. It can reduce the residual oil content in carbon black and improve its toluene transparency.
- Precisely control the pyrolysis reaction temperature. It can reduce the TPH (total petroleum hydrocarbons) content in carbon black.
- Control the oxygen concentration during pyrolysis. It can prevent the formation of incomplete pyrolysis products, such as residual oil and impurities in the carbon black.
2. Coarse Grinding
Process Principle
The pyrolytic carbon black particles are relatively large after pyrolysis. Typically, a vertical grinding mill is used to grind the carbon black powder to 300-800 mesh for subsequent processing. The coarse grinding process includes the following steps:
- Crushing: Large carbon black particles are rapidly broken down into smaller particles through physical impact and compression.
- Grinding: The grinding roller and grinding plate work together through a pressing action to further refine the carbon black to the required particle size.
- Classifying: Centrifugal force or air classification devices are used to separate the carbon black particles that do not meet the required particle size.
- Dust Removal: A pulse dust collection system is employed to handle dust, ensuring a clean and safe production environment.
Core Process
- Precise control of particle size during the grinding process. It ensures that the powder meets the requirements for the subsequent granulation process.
- Ensure uniform particle distribution. Uneven particle sizes can lead to instability during the granulation process.
3. Wet Granulation
Process Principle
The coarse-ground carbon black powder needs to undergo a wet granulation process to form standardized particles. The process is as follows:
- Feeding: First, the coarse-ground carbon black powder is fed into the granulator by a feeding screw.
- Binder Addition: After entering the granulator, an appropriate amount of liquid binder is added to help bind the powder.
- Forced Agglomeration: The rotating action of the granulating teeth forces the powder to agglomerate, forming spherical particles.
- Particle Formation: Finally, carbon black particles with a stable diameter ranging from 1 to 2 mm are formed.
Process Comparison
Compared to dry granulation, wet granulation has the following significant advantages:
- Particle Shape: Wet granulation results in more uniform particle shapes, with a more concentrated particle size distribution.
- Particle Strength: Wet granulation produces carbon black particles with higher strength compared to those formed by natural agglomeration devices.
- Balling Rate & Fineness: Wet granulation achieves a higher balling rate and a fineness rate as low as 3%.
4. Continuous Drying
Process Principle
Dry the carbon black particles produced by wet granulation to remove excess moisture. The continuous drying process consists of the following steps:
- Feeding: The Z-shaped elevator transports the carbon black particles to the drying furnace.
- Drying: The carbon black particles continuously rotate in the drum. Under the action of hot air, heat causes the moisture on the surface of the particles to evaporate until the moisture content drops to ≤1%.
- Discharge: The heating system in the hot air furnace ensures that the drying time, from feeding to discharge, takes approximately 40 minutes, with continuous discharge capability.
Core Process
- Ensure heat each particle evenly. It effectively removes moisture while avoiding over-drying or baking.
- A well-designed hot air circulation system helps reduce energy consumption and improves drying efficiency.
5. Screening and Packaging
Process Principle
We can break down the screening and packaging process for the dried carbon black particles into the following steps:
- Cooling: The dried carbon black particles naturally cool down to room temperature.
- Feeding: The Z-shaped elevator transports the cooled carbon black particles to the screening system.
- Screening: Sent the qualified particles (1-2mm) to the finished product bin after screening the particles. Particles that do not meet the size requirements return to the grinding system for further processing.
- Dust Removal: A pulse dust collector above the bin collects dust, which is then transported to the carbon black powder bin.
- Packaging: Pack the qualified carbon black particles into bags for easy storage and transportation.
Core Process
- Ensure particle size compliance: Ensure the particles meet the required product size, guaranteeing consistency of the final product.
- Reduce the generation of non-compliant particles: Return waste particles to the grinding system for reprocessing, minimizing production losses.
Contact Us
Future applications of pyrolytic carbon black are becoming increasingly promising. Beston Group offers a complete set of pyrolytic carbon black grinding and granulation process solutions. We help customers improve production efficiency while meeting environmental standards. So, if you have any needs, feel free to contact us for more information on solutions and technical support.
