Kinetic mechanism of desilicated fly ash lime consumption

T. Falayi; F.N. Okonta; F. Ntuli

doi:10.5755/j01.ms.24.2.14284

Kinetic mechanism of desilicated fly ash lime consumption

T. Falayi, F.N. Okonta, F. Ntuli

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

This paper presents study of the kinetic mechanism of lime consumption using desilicated fly ash (DFA). Desilicated fly ash (DFA) a residue from leaching of silica from fly ash was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40 ºC, 80 ºC and 100 ºC for 4 days. 80 ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.6 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol and a reaction grade of 3 meaning that the reaction was controlled by diffusion of reactants through a dense layer of reaction products. The main hydration products were calcium silicate hydrate and tricalcium aluminate. Toxicity leaching tests showed a 79 % reduction in the leachability of trace and heavy metals. Therefore, DFA can successfully be stabilised using lime. © 2018, Kauno Technologijos Universitetas. All rights reserved.

Original language	English
Pages (from-to)	192-196
Number of pages	5
Journal	Medziagotyra
Volume	24
Issue number	2
DOIs	https://doi.org/10.5755/j01.ms.24.2.14284
Publication status	Published - 2018

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title = "Kinetic mechanism of desilicated fly ash lime consumption",

abstract = "This paper presents study of the kinetic mechanism of lime consumption using desilicated fly ash (DFA). Desilicated fly ash (DFA) a residue from leaching of silica from fly ash was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40 ºC, 80 ºC and 100 ºC for 4 days. 80 ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.6 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol and a reaction grade of 3 meaning that the reaction was controlled by diffusion of reactants through a dense layer of reaction products. The main hydration products were calcium silicate hydrate and tricalcium aluminate. Toxicity leaching tests showed a 79 % reduction in the leachability of trace and heavy metals. Therefore, DFA can successfully be stabilised using lime. {\textcopyright} 2018, Kauno Technologijos Universitetas. All rights reserved.",

author = "T. Falayi and F.N. Okonta and F. Ntuli",

note = "Export Date: 19 June 2018",

year = "2018",

doi = "10.5755/j01.ms.24.2.14284",

language = "English",

volume = "24",

pages = "192--196",

journal = "Medziagotyra",

issn = "1392-1320",

publisher = "Kauno Technologijos Universitetas",

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TY - JOUR

T1 - Kinetic mechanism of desilicated fly ash lime consumption

AU - Falayi, T.

AU - Okonta, F.N.

AU - Ntuli, F.

N1 - Export Date: 19 June 2018

PY - 2018

Y1 - 2018

N2 - This paper presents study of the kinetic mechanism of lime consumption using desilicated fly ash (DFA). Desilicated fly ash (DFA) a residue from leaching of silica from fly ash was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40 ºC, 80 ºC and 100 ºC for 4 days. 80 ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.6 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol and a reaction grade of 3 meaning that the reaction was controlled by diffusion of reactants through a dense layer of reaction products. The main hydration products were calcium silicate hydrate and tricalcium aluminate. Toxicity leaching tests showed a 79 % reduction in the leachability of trace and heavy metals. Therefore, DFA can successfully be stabilised using lime. © 2018, Kauno Technologijos Universitetas. All rights reserved.

AB - This paper presents study of the kinetic mechanism of lime consumption using desilicated fly ash (DFA). Desilicated fly ash (DFA) a residue from leaching of silica from fly ash was stabilised using lime at elevated temperatures. DFA and lime were mixed in different ratios at optimum moisture content and maximum dry density and then cured at 40 ºC, 80 ºC and 100 ºC for 4 days. 80 ºC was found to be the optimum curing temperature. The DFA: lime ratio of 70:30 was found to have an average UCS of 8.6 MPa. Lime consumption was found to follow modified Jander kinetics with activation energy of 16 kJ/mol and a reaction grade of 3 meaning that the reaction was controlled by diffusion of reactants through a dense layer of reaction products. The main hydration products were calcium silicate hydrate and tricalcium aluminate. Toxicity leaching tests showed a 79 % reduction in the leachability of trace and heavy metals. Therefore, DFA can successfully be stabilised using lime. © 2018, Kauno Technologijos Universitetas. All rights reserved.

U2 - 10.5755/j01.ms.24.2.14284

DO - 10.5755/j01.ms.24.2.14284

M3 - Article

SN - 1392-1320

VL - 24

SP - 192

EP - 196

JO - Medziagotyra

JF - Medziagotyra

IS - 2

ER -

Kinetic mechanism of desilicated fly ash lime consumption

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