Use of fly ash and phosphogypsum for the synthesis of belite-sulfoaluminate clinker

Abstract

Fly ash and phosphogypsum were used as Naturally Occurring Radioactive Materials (NORM) by-products for the synthesis of belite-sulfoaluminate clinkers. The influence of raw mixture composition and firing temperature was investigated. Clinkers and cements were examined by X-ray powder diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. The compressive strength of the cements was determined after 28 days. Clinker phases identified included ye’elimite, ß-phase of belite, ternesite and gehlenite, while the main hydration product of the cement pastes was ettringite. The results showed that belite-sulfoaluminate cements can be fabricated with a compressive strength of 45.9 N/mm2 by firing the raw mixture (70 wt.% marl, 10 wt.% bauxite and 20 wt.% phosphogypsum) at a temperature of 1320°C/1h.

Technical and radiological characterisation of fly ash and bottom ash from thermal power plant

“…Significant amounts of ashes are already used in range of applications, but still there is need to address the potential reuse of ashes. Recent literature reports the application of FA in construction: as raw material in Portland cement clinker [4] and belite-sulfoaluminate clinkers [5], as pozzolanic addition in cement [6], concrete [6,7], light weight aggregate [6], bricks [8], glass-ceramics [9] etc. Also, other uses are being developed, like adsorbents [6,10], zeolites [11], macro and micro nutrients in agriculture [10].…”

Conversion of coal fly ash glass into glass-ceramics by controlled thermal treatment

“…The high tendency for crystallization of the parent glass was confirmed by the Hruby coefficient (KH = 2.3). Glass ceramics with a density in the range of 1.6-1.8 g/cm 3 and a porosity from 40 to 30 % were fabricated in the temperature interval 800-1050 ºC/30, 60, and 120 min, while the bending strength and Emodulus varied from 8 to 30 MPa and from 6 to 15 GPa, respectively. The maximal values of density (2.2 g/cm 3 ), bending strength (78 MPa), and Emodulus (32 GPa) and minimal porosity (12.8 %) were achieved for glass-ceramics sintered at 1100 ºC/60 min.…”

“…In the process of the combustion of coal, large quantities of fly ash are produced [1]. According to the European statistics for 2016 [2], about 64 % of the total production in the EU belongs to fly ash, of which only 40 % are used, most often in the cement industry as supplements in cement [3] or concrete production [4]. Coal is a dominant resource for the production of electricity in the Republic of North Macedonia, where more than 80 % of the electrical power requirements are generated from REK Bitola, the largest lignite power plant located in nearby Bitola [5].…”

Resistance to frost action and microbiological corrosion of novel ceramic composites

“…The ashes mostly contain particles with dimensions of (50 -100) µm, therefore no extra milling is needed. The application of fly ashes, as industrial wastes from coal combustion process in thermal power plants, in cement industry, in road base construction and agriculture is well known [2,3]. The potential use of this secondary raw material in building and construction industry minimizes the ecological footprint of this sector.…”