Microspheres are formed during the mineral transformation stage in coal combustion. Their content in fly ashes from the combustion of different types of coals varies over a rather wide range from 0.01 to 4.8 wt.%. The microspheres have three main elements, silicon, aluminum and iron, the oxides of which account for about 89.0 wt.% of the material. Mineralogical analysis using XRD shows that microspheres mainly contain mullite and quartz as the main crystalline phases. The size of microspheres varies between 5 and 500 μm and the most common dimension is 20÷300 μm. Microspheres are characterized by a low bulk density (0.2÷0.8 g/cm3) and can be easily separated by gravitational methods in the form of a concentrate in aqueous media or collected from the water surface of lagoons intended for storing of fly ash and slag. The unique properties of microspheres suggest the wide range of their use. They are currently used as lightweight filler which improves the thermal insulation properties of mortars and concretes based on mineral binders.
Authors
Additional information
- Category
- Publikacja w czasopiśmie
- Type
- artykuły w czasopismach recenzowanych i innych wydawnictwach ciągłych
- Language
- angielski
- Publication year
- 2016
