In 1973, in Pittsburgh International Ash Conference, Dr. Bithua discussed the possibility of extracting hollow glass beads from fly ash. Because the hollow glass beads of fly ash have abundant raw materials, low price, and can turn waste into treasure, etc., the hollow glass beads used in early solid buoyancy materials were mostly extracted from the fly ash after coal combustion in thermal power plants. As it is extracted by wind or water separation, it is a kind of micro-state, light, hollow, smooth surface, beads that can float on the water surface, so it is generally called floating beads.
Float beads are mainly composed of SiO₂ and metal oxide, accounting for only 1% to 3% of the total weight of fly ash, particle diameter of 0.2400um, density is 0.4~0.8g/cm³, the hollow part of the gas is ammonia and CO₂ produced by the reaction of iron oxide and dispersed carbon, thermal photo (1000 times amplified) low conductivity, It can be added to solvents, organic chemicals, water, acids or lye without changing its chemical properties.
Compared with artificial microbeads, the price of floating beads is about 50% to 200% lower, but its average density is slightly higher than artificial hollow glass microbeads, wide particle size distribution, poor purity, and must be properly separated and graded before use, especially its high particle density (generally higher than 0.6g/cm³), not suitable for the preparation of buoyancy materials for deep diving. (Excerpt from 《Solid Buoyant Materials》)