Mineralogy and glass content of Fe‐rich fayalite slag size fractions and their effect on alkali activation and leaching of heavy metals

Alkali-activated materials (AAMs) are an environmentally friendly option for Portland cement mortars and concretes. Many industrial residues such as blast furnace slag and coal fly ash have been extensively studied and applied as AAM precursors but much less focus has been on the use of fayalite slags. Water-cooled fayalite slag comes in granular form, which is then milled into fine powder (d50 ~10 microns) prior to its alkali activation. In addition, the un-milled granular fayalite slag can be used as an aggregate to replace sand in mortar. The alkaline solution utilized for the study was a mix of 10 M sodium hydroxide solution and commercial potassium silicate solution. A liquid to solid ratio of 0.15 was held constant for all the mixes. The particle size distributions of the binder and the aggregates were optimized, and the microstructure and chemical composition of the interfacial transition zone (ITZ) was studied using scanning electron microscope coupled with energy dispersive X-ray spectroscopy. ITZ is a region that exists between the aggregate and the binder and this can influence the mechanical and transport properties of the construction materials. The results showed that the mechanical properties of mortar having fayalite slag as aggregate and binder was significantly higher than one with standard sand as aggregate. No distinct ITZ was found in the samples with fayalite slag as aggregate. The outer rim of the fayalite slag aggregate participated in the hardening reaction and this significantly contributed to the bonding and microstructural properties of the mortar samples. In contrast, an ITZ was observed in mortar samples with standard sand aggregates, which contributed to its lower strength.

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Partitioning of heavy metals in different particle-size fractions of soils from former mining and smelting locations in Austria

EURASIAN JOURNAL OF SOIL SCIENCE (EJSS) ◽

10.18393/ejss.837139 ◽

2021 ◽

Vol 10 (2) ◽

pp. 123-131

Author(s):

Anto JELECEVİC ◽

Manfred SAGER ◽

Daniel VOLLPRECHT ◽

Markus PUSCHENREİTER ◽

Peter LİEBHARD

Keyword(s):

Heavy Metals ◽

Particle Size ◽

Size Fractions ◽

Particle Size Fractions ◽

Mining And Smelting

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Stabilization of Ash and Slag from Combustion of Medical Waste in the Geopolymers Matrix

E3S Web of Conferences ◽

10.1051/e3sconf/20184400110 ◽

2018 ◽

Vol 44 ◽

pp. 00110 ◽

Cited By ~ 4

Author(s):

Dariusz Mierzwiński ◽

Michał Łach ◽

Janusz Mikuła ◽

Marcin Goły

Keyword(s):

Heavy Metals ◽

Compressive Strength ◽

Fly Ash ◽

Coal Combustion ◽

Water Glass ◽

Medical Waste ◽

Waste Materials ◽

Alkali Activation ◽

Related Research ◽

Geopolymer Matrix

This paper regards the possibility of using geopolymer matrix to immobilize heavy metals present in ash and slag from combustion of medical waste. In the related research one used the fly ash from coal combustion in one Polish CHP plant and the waste from two Polish incineration plants. It was studied if the above-named waste materials are useful in the process of alkali-activation. Therefore, two sets of geopolymer mixtures were prepared containing 60 and 50% of ash and slag from the combustion of medical waste. The remaining content was fly ash from coal combustion. The alkali-activation was conducted by means of 14M solution of NaOH and sodium water glass. The samples, whose dimensions were in accordance with the EN 206-1 norm, were subjected to 75°C for 24 h. According to the results, the geopolymer matrix is able to immobilize heavy metals and retain compressive strength resembling that of C8/10 type concrete.

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The Leachability of Heavy Metals from Alkali-Activated Fly Ash and Blast Furnace Slag Matrices

Materials Science Forum ◽

10.4028/www.scientific.net/msf.851.141 ◽

2016 ◽

Vol 851 ◽

pp. 141-146

Author(s):

Jan Koplík ◽

Miroslava Smolková ◽

Jakub Tkacz

Keyword(s):

Mechanical Properties ◽

Heavy Metals ◽

Blast Furnace ◽

Fly Ash ◽

Blast Furnace Slag ◽

Inductively Coupled Plasma ◽

Emission Spectrometry ◽

Alkali Activation ◽

Furnace Slag ◽

Alkali Activated

The ability of alkali-activated materials (AAMs) to fix and immobilize heavy metals was investigated. Two raw materials were used to prepare alkali-activated matrices – high-temperature fly ash and blast furnace slag (BFS). NaOH served as an alkaline activator. Two heavy metals (Mn, Ni) were added in different amounts to find out the influence of dosage of heavy metal on the mechanical properties of the matrices and the leachability. Leachability was measured as concentration of heavy metals in leachates (ČSN EN 12457-4) by inductively coupled plasma/optical emission spectrometry (ICP/OES). Structure of prepared matrices was characterized by scanning electron microscopy (SEM). Increasing of addition of heavy metals led to decrease of mechanical properties of matrices. The leaching tests showed, that both matrices can immobilize Mn and Ni in dosages of 0.1 – 2,5%. Higher dosages caused deterioration of the matrices and increased the leachability. After alkali activation both heavy metals were transformed into the form of insoluble salts.

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Assessment of sediment toxicity by metal speciation in different particle-size fractions of river sediment

Water Science & Technology ◽

10.2166/wst.2003.0694 ◽

2003 ◽

Vol 47 (7-8) ◽

pp. 233-241 ◽

Cited By ~ 25

Author(s):

J.G. Lin ◽

S.Y. Chen ◽

C.R. Su

Keyword(s):

Heavy Metals ◽

Particle Size ◽

Aquatic Ecosystem ◽

Metal Speciation ◽

Sediment Toxicity ◽

Clay Fraction ◽

Potential Toxicity ◽

Size Fractions ◽

Particle Size Fractions ◽

Mn Oxide

Mobility and toxicity of metals associated with sediments are generally affected by metal speciation and granular compositions. Due to the various speciation patterns of heavy metals in sediments, it is not reliable to assess the potential toxicity of heavy metals on the aquatic environment with the total concentrations of heavy metals in sediments. The purposes of this study were to investigate the distribution of metal speciation in different particle-size fractions of sediments collected from two rivers (the Ke-Ya River and Ell-Ren River) in Taiwan, and to assess their potential toxicity to the aquatic ecosystem. Metals in the exchangeable, carbonate-bound and Fe/Mn oxide-bound forms obtained by sequential extraction were considered to be mobile and related with anthropogenic pollution. The degree of metal pollution and potential toxicity of sediments were higher in the lower reaches of both rivers. The metal speciation in sediments had a bimodal distribution over particle-size fractions. Heavy metals were subject to accumulation in the silt/clay fraction (<25μmm) and coarse sand (420-2,000μmm). By normalizing the sum of the exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals, it suggested that the potential toxicity to the aquatic ecosystem was caused by the fine sediments as well as coarse sediments.

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