THE RECOVERY OF MAGNETIC MICROSPHERES AND CENOSPHERES OF THE STABILIZED COMPOSITION FROM COAL POWER PLANT FLY ASH

摘要

Low level of coal mineral components utilization that is caused by a variability of grain-size distribution, chemical and phase composition of fly and bottom ash is the important problem of power engineering. The development of the recovery processes of fixed composition products from coal power plant fly ash enables to expand essentially the areas of ash component application. Different types of microspheres are formed from mineral coal components in the process of melting and thermochemical transformation during coal combustion and are concentrated in fly ash. Magnetic products of coal power plant fly ash are glass crystalline microspheres on the basis of solid solutions of magnetite Fe_3O_4 and Mg(Mn)-ferrite which have a high magnetic susceptibility, bulk and true density. Another type of microspheres are cenospheres, or hollow aluminosilicate microspheres, which have a low bulk density, high heat-resistant and mechanical durability. High thermal stability of the microspheres, constant phase structure and low cost give an opportunity to use them as catalysts (and support of catalysts) of deep oxidation of hydrocarbons and other types of the wastes. The recovery of magnetic and hollow microspheres as stabilized products allows to improve the technological properties of ashes in order to produce building and heat-insulating materials, to expand areas of possible application and to increase coal power plant fly ash utilization. The aim of present paper is to develop the methods of recovering magnetic microspheres and cenospheres of stabilized (fixed) composition and to study their properties and the areas of application.