The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction

This study developed an industry-applicable, thermal decomposition methodology for quantification of carbonate mineral acid neutralisation capacity (ANC<sub>therm-carb</sub>) for waste rock, tailings, and other mined materials. Standard titration-based methods for ANC can be compromised...

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Main Authors: Andrea R. Gerson, Paul Weber, Roger St. C. Smart, George Levay, Mike Hutton-Ashkenny, Rosalind Green
Format: Article
Language:English
Published: MDPI AG 2021-10-01
Series:Minerals
Subjects:
Online Access:https://www.mdpi.com/2075-163X/11/11/1181
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author Andrea R. Gerson
Paul Weber
Roger St. C. Smart
George Levay
Mike Hutton-Ashkenny
Rosalind Green
author_facet Andrea R. Gerson
Paul Weber
Roger St. C. Smart
George Levay
Mike Hutton-Ashkenny
Rosalind Green
author_sort Andrea R. Gerson
collection DOAJ
description This study developed an industry-applicable, thermal decomposition methodology for quantification of carbonate mineral acid neutralisation capacity (ANC<sub>therm-carb</sub>) for waste rock, tailings, and other mined materials. Standard titration-based methods for ANC can be compromised due to contributions from silicate minerals, ion exchange, Fe-rich carbonates, and other transition metal carbonates. C emission (CO<sub>2</sub> and CO) was measured using IR in a N<sub>2</sub> atmosphere. C<sub>neut</sub> (wt%) was calculated using the C emission at 800 or 1000 °C minus the C emission at 400, 450 or 500 °C and the weight of sample prior to decomposition (Equation (2) of this manuscript). This value was then input into Equation (3) of this manuscript to calculate ANC<sub>therm-carb</sub>. Good correlation of ANC<sub>therm-carb</sub> for single-mineral carbonates with ANC<sub>calc</sub>, calculated from bulk assay concentrations for Mg, K, Na, Ca, and Mn, was achieved. Thereafter, 18 waste rock samples were examined, resulting in the correlation of ANC<sub>therm-carb</sub> versus non-standard ANC<sub>titrate-carb</sub> (titration methodology adapted to focus on carbonate neutralisation only) with R<sup>2</sup> = 0.96. This correlation is valid for samples containing both non-neutralising carbonates (siderite) and sources of neutralisation arising from non-carbonates (Mg-clay) within this waste rock system. Typically, mining operations use total C measurements for assessment of carbonate neutralisation potential in the block and mining model. This method provides an effective means to cheaply analyse for carbonate neutralisation potential with assignment of potentially acid-forming and non-acid-forming blocks to waste rock cells, etc.
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spelling doaj.art-2188342e165549f7ba917143fddbc4aa2023-11-23T00:31:30ZengMDPI AGMinerals2075-163X2021-10-011111118110.3390/min11111181The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage PredictionAndrea R. Gerson0Paul Weber1Roger St. C. Smart2George Levay3Mike Hutton-Ashkenny4Rosalind Green5Blue Minerals Consultancy, Wattle Grove 7109, AustraliaMine Waste Management, Christchurch 8440, New ZealandBlue Minerals Consultancy, Wattle Grove 7109, AustraliaLevay & Co. Environmental Services, Edinburgh 5106, AustraliaRio Tinto Research & Technical Development Centre, Melbourne 3083, AustraliaRio Tinto, Copper & Diamonds, Brisbane 4000, AustraliaThis study developed an industry-applicable, thermal decomposition methodology for quantification of carbonate mineral acid neutralisation capacity (ANC<sub>therm-carb</sub>) for waste rock, tailings, and other mined materials. Standard titration-based methods for ANC can be compromised due to contributions from silicate minerals, ion exchange, Fe-rich carbonates, and other transition metal carbonates. C emission (CO<sub>2</sub> and CO) was measured using IR in a N<sub>2</sub> atmosphere. C<sub>neut</sub> (wt%) was calculated using the C emission at 800 or 1000 °C minus the C emission at 400, 450 or 500 °C and the weight of sample prior to decomposition (Equation (2) of this manuscript). This value was then input into Equation (3) of this manuscript to calculate ANC<sub>therm-carb</sub>. Good correlation of ANC<sub>therm-carb</sub> for single-mineral carbonates with ANC<sub>calc</sub>, calculated from bulk assay concentrations for Mg, K, Na, Ca, and Mn, was achieved. Thereafter, 18 waste rock samples were examined, resulting in the correlation of ANC<sub>therm-carb</sub> versus non-standard ANC<sub>titrate-carb</sub> (titration methodology adapted to focus on carbonate neutralisation only) with R<sup>2</sup> = 0.96. This correlation is valid for samples containing both non-neutralising carbonates (siderite) and sources of neutralisation arising from non-carbonates (Mg-clay) within this waste rock system. Typically, mining operations use total C measurements for assessment of carbonate neutralisation potential in the block and mining model. This method provides an effective means to cheaply analyse for carbonate neutralisation potential with assignment of potentially acid-forming and non-acid-forming blocks to waste rock cells, etc.https://www.mdpi.com/2075-163X/11/11/1181acid mine drainagemine waste rock characterisationacid neutralisation capacitymineral carbonatesthermal decomposition
spellingShingle Andrea R. Gerson
Paul Weber
Roger St. C. Smart
George Levay
Mike Hutton-Ashkenny
Rosalind Green
The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
Minerals
acid mine drainage
mine waste rock characterisation
acid neutralisation capacity
mineral carbonates
thermal decomposition
title The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
title_full The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
title_fullStr The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
title_full_unstemmed The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
title_short The Application of Thermal Decomposition for Determination of Carbonate Acid-Neutralising Capacity for Improved Acid Mine Drainage Prediction
title_sort application of thermal decomposition for determination of carbonate acid neutralising capacity for improved acid mine drainage prediction
topic acid mine drainage
mine waste rock characterisation
acid neutralisation capacity
mineral carbonates
thermal decomposition
url https://www.mdpi.com/2075-163X/11/11/1181
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