A cenospheres are lightweight, inert, hollow sphere made largely of silica and alumina and filled with air or inert gas, typically produced as a byproduct of coal combustion at thermal power plants. The color of cenospheres varies from gray to almost white and their density is about 0.4–0.8 g/cm3 (0.014–0.029 lb/cu in), which gives them a great buoyancy
Benefits of Cenospheres
- Strength: Bonding, internal structure; asphalt, concretes, paints, ceramics.
- Sphericity: Ball bearing effect for molding, trowel work, lubricity.
- Reduced Weight: Light-weighting; filler loading, reduced shrinkage, lower viscosity.
- Sound Attenuation: Noise and RF absorption and reflection.
- Refractory: Foundries and high temperature coatings and flame-retardants.
- Thermal reflectivity.
Cenospheres can be used for various utilities such as:
- Ceramics→ Tiles, firebricks, coatings, refractory, insulating materials, and high temperature cement.
- Construction → Acoustic enhancement, acrylic, adhesives, coatings, backer board, wall panels, cements, cultured marble, etc.
- Coatings→ highways, driveways, underground pipes, and heat-shielding requirements.
- Automotive→ Soundproofing, under-coatings, brake pads, sealants, body fillers and putties, composites, steering wheels.
- Recreation→ flotation, bowling balls, surf boards, golf equipment, marine compounds, kayaks.
- Oil field→ Cementing, drilling muds (decrease slurry density without increased water content).
- Plastics→ Polyethylene, polypropylene, nylon, PVC, compounding, film, urethane, potting compounds.
- Aerospace→ Ceramic insulation, tortuous path matrix, propeller blades.
- Cenospheres Production Process- The process of burning coal in thermal power plants produces fly ash containing ceramic particles made largely of alumina and silica. They are produced at temperatures of 1,500 to 1,750 °C (2,730 to 3,180 °F) through complicated chemical and physical transformation. Their chemical composition and structure varies considerably depending on the composition of coal that generated them.
- The ceramic particles in fly ash have three types of structures. The first type of particles are solid and are called precipitator. The second type of particles are hollow and is called cenospheres. The third type of particles are called plerospheres, which are hollow particles of large diameter filled with smaller size precipitator and cenospheres.
Thus Cenospheres are hard and rigid, light, waterproof, in noxious, and insulative. This makes them highly useful in a variety of products, notably fillers.