51 / 2023-03-30 17:43:24

STUDY OF ASH AND SLAG WASTES FOR THEIR USE AS BUILDING MATERIALS

ash and slag ovals, thermal power plant, ecology, secondary resources, building materials.

Relevance of study. Wastes from coal combustion in the Ekibastuz coal basin amount to many millions of tons annually. Huge amounts of waste accumulate near metropolitan areas, alienating expensive suburban land with a non-linear growth trend and significantly reducing market value of nearby land and buildings, and require huge maintenance costs. Relevance of this article is solution of environmental problems of the Almaty region, as well as possibility of obtaining gas silicate with a minimum content of cement in concrete, as the most expensive component. This article discusses use of ash and slag waste as building materials in the Republic of Kazakhstan.

Research purpose is to study physical and chemical properties of ash and slag waste from combustion of Ekibastuz coals and to determine possibility of obtaining demanded building materials from them to reduce formation of ash dumps and environmental load.

            Methodology. To study phase composition and structure of ash and slag waste, methods of X-ray phase and differential thermal and chemical analyzes were used on the latest installations of leading countries.

            To determine phase composition of cements and ash, modernized DRON-3M diffractometer on CuKα radiation with software was used. X-ray patterns were obtained in the range of 2θ (angles) from 10 to 70º.

    To determine chemical composition of ash and slag waste, ash samples were taken from electrostatic precipitators and ash and slag dumps in accordance with methodology of RD 34.09.603-88 «Guidelines for organizing control of composition and properties of ash and slag sold to consumers by thermal power plants». Сhemical composition was carried out using energy-dispersive X-ray fluorescence spectrometer EDX-8000, and granulometric composition was carried out using Analizette 22 MicroTec Fritsch GmbH instrument (Germany). Fly ash micrograph was taken with a Superprobe-733 scanning electron microscope with software.

            Results. Chemical and granulometric composition of ash and slag was determined. Performed X-ray phase and differential thermal analysis. Analysis of chemical composition of the Ekibastuz ash gives idea of composition of mineral substances of coal. Main constituents are oxides of silicon and aluminum, there is also a large amount of iron oxide. Knowledge of chemical composition of ash is necessary to decide whether it can be used to produce building materials. Thus, all conducted studies have shown possibility of using ash and slag waste in the production of building materials to reduce anthropogenic load on environment.

Novelty lies in the technology development that allows to increase degree of complexity and environmental safety of technogenic waste development - this is development of industrial and innovative power of state, respect for natural resources and environment. Obtaining ash-gas concrete with the lowest possible density and the highest strength of products, i.e. at the highest value of coefficient of constructive quality that meets requirements of standard for density, strength and frost resistance of products.

Practical value  lies in the fact that production of building materials quickly pays off, does not require expensive installations, tools and equipment, and will also allow solving environmental problem by reducing volume of ash dumps, unload occupied lands for household needs, from ash and slag mixtures.