... mm , Hollow glass micropheres is a hollow ball collected from coal powder,its coloure is light grey,thin wall, ... hollow, high strength and durable, resistant to temperature etc.It has been uesed in all fields1)Chemicals Compositions :ItemsSiO2Al2O3Fe2O3SO3CaOMgOK2ONa2OContent(%)50-5525 ... %1.33Oil Absorptiong(oil)/g0.68-0.69Volume Weight kg/m3250---450Granular diameter mm0.1Humidity 1.6 max3)Granulation: ...