Synthesis and characterization of geopolymers derived from coal gangue, fly ash and red mud

Koshy, Nevin; Dondrob, Kunga; Hu, Liming; Wen, Quan; Meegoda, Jay N.

doi:10.1016/j.conbuildmat.2019.02.076

Cited by 153 publications

(41 citation statements)

References 38 publications

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“…(2018) , Moukannaa et al. (2018) 881–870 870 Si–OH bending mode or tetrahedral bending Al Koshy et al. (2018) 800–770 796 Si–O–Si symmetric stretching Moukannaa et al.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of coal fly ash and palm oil fuel ash modified artisanal and small-scale gold mine (ASGM) tailings based geopolymer using sugar mill lime sludge as Ca-based activator

Opiso

Tabelin

Maestre

et al. 2021

Heliyon

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The continuous accumulation of artisanal and small-scale gold mining (ASGM) tailings in the Philippines without adequate storage and disposal facility could lead to human health and environmental disasters in the long run. In this study, ASGM tailings was simultaneously stabilized and repurposed as construction material via geopolymerization using coal fly ash, palm oil fuel ash and a powder-based alkali activator. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) identified iron sulfides in the tailings containing arsenic (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn), which could be released via weathering. The average unconfined compressive strengths (UCS) of tailings-based geopolymers at 14 days curing were 7.58 MPa and 7.7 MPa with fly ash and palm oil fuel ash, respectively. The tailings-based geopolymers with palm oil fuel ash had higher UCS most likely due to CASH reaction product formation that improved strength formation. The toxicity characteristic leaching procedure (TCLP) results showed very low leachabilities of As, Pb and Fe in the geopolymer materials suggesting ASGM tailings was effectively encapsulated within the geopolymer matrix. Overall, the geopolymerization of ASGM tailings is a viable and promising solution to simultaneously stabilize mining and industrial wastes and repurpose them into construction materials.

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“…(2018) , Moukannaa et al. (2018) 881–870 870 Si–OH bending mode or tetrahedral bending Al Koshy et al. (2018) 800–770 796 Si–O–Si symmetric stretching Moukannaa et al.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of coal fly ash and palm oil fuel ash modified artisanal and small-scale gold mine (ASGM) tailings based geopolymer using sugar mill lime sludge as Ca-based activator

Opiso

Tabelin

Maestre

et al. 2021

Heliyon

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“…The Si/Al and Na/Al ratios were determined based on the Si, Al, and Na contents in the fly ash, red mud, and sodium metasilicate. Based on the preliminary results of FA4, FA6, and FA8 [10], the FA:RM ratio of 8:2 was found to yield the highest strength. Hence, the influence of other parameters, viz., L/S, Si/Al, and Na/Al ratios, on the unconfined compressive strength (UCS) were studied based on this FA:RM ratio of 8:2, as shown in Table 2.…”

Section: Methodsmentioning

confidence: 99%

Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

Koshy

Dondrob

et al. 2019

Crystals

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Aluminosilicate gels form geopolymers and nanocrystalline zeolites which have comparable strength properties, making them a potential replacement for ordinary Portland cement. The study explores the use of two untreated industrial wastes, Class-F fly ash and red mud, for synthesizing geopolymeric material at ambient synthesis conditions. The high alkalinity present in the red mud was exploited for the dissolution of silica in the fly ash and red mud. The mechanical, mineralogical, microstructural, and pore characteristics were analyzed and the contributions of curing period, Si/Al, Na/Al, and liquid-to-solid (L/S) ratios on the compressive strength of the end products were also investigated. The alkalinity of the system due to the red mud was adequate for the dissolution of raw fly ash and the subsequent formation of aluminosilicate gels. The strength of the end product was directly proportional to the initial Si/Al ratio and the specimens with highest fly ash content exhibited highest compressive strength values after 28 days of curing. Furthermore, fly ash contributed to the formation and distribution of interstitial and capillary pores in the aluminosilicate matrix. The lowest L/S ratio of the initial mix resulted in the end product with the highest unconfined compressive strength.

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“…Approximately 0.6–2.5 tons of red mud are produced for every ton of alumina [2,3]. Approximately 150 million tons of red mud are produced annually worldwide, and the annual generation of red mud has grown since 2015 [4,5]. Currently, deep-sea dumping, landfilling, and impoundment are the most common methods for red mud management [6].…”

Section: Introductionmentioning

confidence: 99%

pH-Dependent Leaching Characteristics of Major and Toxic Elements from Red Mud

Cui

Chen

Zhang

et al. 2019

IJERPH

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This study analyzes the leaching behavior of elements from red mud (bauxite residue) at pH values ranging from 2 to 13. The leaching characteristics of metals and contaminated anions in five red mud samples produced by Bayer and combined processes were analyzed using the batch leaching technique following the US Environmental Protection Agency (USEPA) Method 1313. In addition, the geochemical model of MINTEQ 3.1 was used to identify the leaching mechanisms of metals. The results showed that Ca, Mg, and Ba follow the cationic leaching pattern. Al, As, and Cr show an amphoteric leaching pattern. The leaching of Cl− is unaffected by the pH. The maximum leaching concentration of the proprietary elements occurs under extremely acidic conditions (pH = 2), except for As. The leaching concentration of F− reaches 1.4–27.0 mg/L in natural pH conditions (i.e., no acid or base addition). At the same pH level, the leaching concentrations of Pb, As, Cr, and Cu are generally higher from red mud produced by the combined process than that those of red mud from the Bayer process. The leaching concentration of these elements is not strongly related to the total elemental concentration in the red mud. Geochemical modeling analysis indicates that the leaching of metal elements, including Al, Ca, Fe, Cr, Cu, Pb, Mg, Ba, and Mn, in red mud are controlled by solubility. The leaching of these elements depended on the dissolution/precipitation of their (hydr)oxides, carbonate, or sulfate solids.

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Synthesis and characterization of geopolymers derived from coal gangue, fly ash and red mud

Cited by 153 publications

References 38 publications

Synthesis and characterization of coal fly ash and palm oil fuel ash modified artisanal and small-scale gold mine (ASGM) tailings based geopolymer using sugar mill lime sludge as Ca-based activator

Synthesis and characterization of coal fly ash and palm oil fuel ash modified artisanal and small-scale gold mine (ASGM) tailings based geopolymer using sugar mill lime sludge as Ca-based activator

Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

pH-Dependent Leaching Characteristics of Major and Toxic Elements from Red Mud

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