Passive remediation of acid mine drainage using cryptocrystalline magnesite: A batch experimental and geochemical modelling approach

Authors

  • Vhahangwele Masindi 1. Environmental Remediation and Water Pollution Chemistry Research Group, Department of Ecology and Resources Management, School of Environmental Science, University of Venda, P/bag X5050, Thohoyandou, 0950, South Africa; 2. CSIR (Council of Scientific and Industrial Research), Built Environment, Building Science and Technology (BST), P.O Box 395, Pretoria, 0001, South Africa
  • Mugera Wilson Gitari Environmental Remediation and Water Pollution Chemistry Research Group, Department of Ecology and Resources Management, School of Environmental Science, University of Venda, P/bag X5050, Thohoyandou, 0950, South Africa
  • Hlanganani Tutu Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, P/Bag X4, WITS, 2050, Johannesburg, South Africa
  • Marinda De Beer DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O Box 395, Pretoria, 0001, South Africa

DOI:

https://doi.org/10.4314/wsa.v41i5.10

Keywords:

acid mine drainage, cryptocrystalline magnesite, toxic metals, geochemical modelling, water treatment

Abstract

Acid mine drainage is generated when mining activities expose sulphidic rock to water and oxygen leading to generation of sulphuric acid effluents rich in Fe, Al, SO4 and Mn with minor concentrations of Zn, Cu, Mg, Ca, Pb depending on the geology of the rock hosting the minerals. These effluents must be collected and treated before release into surface water bodies. Mining companies are in constant search for cheaper, effective and efficient mine water treatment technologies. This study assessed the potential of applying magnesite as an initial remediation step in an integrated acid mine drainage (AMD) management system. Neutralization and metal attenuation was evaluated using batch laboratory experiments and simulations using geochemical modelling. Contact of AMD with cryptocrystalline magnesite for 60 min at 1 g: 100 mℓ S/L ratio led to an increase in pH, and a significant increase in metals attenuation. Sulphate concentration was reduced to ≈1 910 mg/ℓ. PH redox equilibrium (in C language) (PHREEQC) geochemical modelling results showed that metals precipitated out of solution to form complex mineral phases of oxy-hydroxysulphates, hydroxides, gypsum and dolomite. The results of this study showed that magnesite has potential to neutralize AMD, leading to the reduction of sulphate and precipitation of metals.

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Published

2015-10-29

Issue

Vol. 41 No. 5 October (2015): Water SA

Section

Research paper

License

Copyright (c) 2022 Vhahangwele Masindi, Mugera Wilson Gitari, Hlanganani Tutu, Marinda De Beer

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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How to Cite

Vhahangwele Masindi (2015) “Passive remediation of acid mine drainage using cryptocrystalline magnesite: A batch experimental and geochemical modelling approach”, Water SA, 41(5 October). doi:10.4314/wsa.v41i5.10.