I. Core Production Processes of Ceramsite
The production process of ceramsite varies depending on raw materials, but the core steps can be summarized into five stages:
1. Raw Material Processing
Based on the type of raw material (e.g., clay, fly ash, sludge, shale), processes such as crushing, screening, or mixing are required. For example, clay is crushed to 100–200 mm and homogenized, while sludge is mixed with fly ash and clay in specific ratios and naturally dewatered in aging piles for 15–20 days to enhance performance.
2. Pelletizing and Shaping
Equipment like roller granulators or pelletizing discs is used to extrude raw materials into 5–10 mm granules. Fly ash ceramsite requires slurry pelletizing, whereas sludge ceramsite relies on high-pressure extrusion from roller granulators.
3. Preheating and Sintering
Granules are treated at high temperatures (typically 1000–1170°C) in rotary kilns or sintering machines. The expansion method (for clay or shale) forms a porous structure via internal gas expansion, while the *sintering method* enhances strength through solid-phase bonding. For instance, sludge ceramsite sintered at 1000°C for 12 minutes achieves a cylinder compressive strength of 5.8 MPa and a water absorption rate of only 7.64%.
4. Cooling and Screening
High-temperature ceramsite is rapidly cooled using vertical coolers or grate coolers. The cooled air is recycled as secondary air, achieving up to 70% energy-saving efficiency. The final product is graded by particle size (e.g., 5 mm, 15 mm, 25 mm) and packaged.
5. Environmental Dust Collection
Kiln exhaust gas is purified through multi-tube coolers and bag filters, ensuring dust emissions meet national standards for clean production.
II. Technological Innovation: Efficiency and Energy Savings
Modern ceramsite production lines significantly improve energy efficiency through equipment optimization:
- Sleeve Drying Technology: Utilizes waste heat from rotary kilns to pre-dry raw materials, reducing fuel consumption by 10%.
- Intelligent Control: Computerized batching systems precisely regulate water and raw material ratios, balancing porosity and strength.
- Waste Recycling: Substitutes traditional clay with river sediment, municipal sludge, etc., reducing natural resource consumption and solid waste pollution. For example, river sediment ceramsite achieves a bulk density as low as 528 kg/m³ and a compressive strength of 35.38 MPa.
III. Environmental Value: Circular Economy from Raw Materials to Applications
1. Green Raw Materials
Utilization of industrial waste (fly ash, coal gangue, sludge) reduces millions of tons of solid waste annually. Adding 10% steel slag enhances ceramsite strength and lowers water absorption.
2. Low-Carbon Processes
Biomass fuels (e.g., rice husks) replace coal, reducing sulfur oxide emissions. Rice bran additives generate CO₂ and water vapor during sintering, ensuring eco-friendly control.
3. Expanded Applications
Ceramsite concrete reduces self-weight by 12.4%, making it ideal for prefabricated buildings. As a biofilter material, it achieves over 93% lead ion adsorption efficiency, aiding wastewater treatment.
IV. Future Outlook: Intelligence and Standardization
With growing market demand, ceramsite production is advancing in two directions:
1. Process Standardization: Establishing national standards for ceramsite filter media, defining strength and porosity metrics to drive high-quality industry development.
2. Equipment Intelligence: Implementing AI algorithms to optimize sintering temperature control and IoT-enabled remote monitoring for enhanced production stability.
