Cenosphere

A cenosphere is a 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. Cenospheres are unique free flowing powders composed of hard shelled, hollow, minute spheres. A small proportion of the pulverised fuel ash (pfa) produced from the combustion of coal in power stations is formed as cenospheres. Cenospheres are made up of silica, iron and alumina. Cenospheres have a size range from 1 to 500 microns with an average compressive strength of 3000+ psi. Colors range from white to dark gray. They are also referred to as microspheres, hollow spheres, hollow ceramic microspheres, microballoons, or glass beads.