Geochemical Aspects at the Tintillo-Corta Atalaya Acid Mine Drainage site, Iberian Pyrite Belt, Southwest Spain

  • Emma Mathewson

    Student thesis: Doctoral Thesis


    Acid mine drainage (AMD) is a major environmental problem in many active and former
    mining regions worldwide. Prediction of the nature of effluents released from mine sites
    and their environmental impacts is a challenging and dynamic problem as AMD is
    affected, both by the textural and compositional features of sulphide ores and their
    weathered spoils and by water-rock interactions in receiving waters.
    This thesis examines AMD processes in the headwater region of the Tintillo River (a high
    level tributary of the Odiel River) that receives effluents draining the spoil heaps of the
    Corta Atalaya (CA) mine, Iberian Pyrite Belt (IPB), South-West Spain. The district and CA
    itself represent some of the largest massive sulphide mines in the world. The aim of the
    work presented here is to assess AMD generation and impacts around the CA mine
    focusing on, (a) AMD generation processes in the mine and its spoil heaps and (b) the
    impacts of site AMD on river water chemistry and river morphology.
    Tintillo River waters are extreme examples of AMD-affected Mg-SO4 type waters
    characterised by high S, Mg, Fe and Al concentrations and low pH (~2.56). Intense
    sulphide oxidation at all scales has resulted in the release of high concentrations of Fe
    and SO4 and accessory metals (e.g. Cu, Zn, Cd, As and Co) into the fluvial network with
    concomitant dissolution of gangue minerals and hydrolysis reactions leading to the
    mobilisation of Mg, Al, Si, K and Na. Future differential rates and products of weathering
    between the meta-rhyolites that dominate CA spoil could profoundly affect the partitioning
    of major and trace elements (e.g. metals co-precipitated, adsorbed and or otherwise
    retained by current secondary mineral accumulations), impacting the subsequent parts of
    the system.
    Two major geomorphological expressions (terrace formations and evaporite
    accumulations) are the result of hydrogeochemical processes following outwash of acidic
    effluents at the study site. Secondary minerals at the site significantly influence the
    geochemical fractionation of hazardous elements. Dissolution of soluble salts
    (characteristically Mg- varieties of magnesiocopiapite, epsomite, and hexahydrite) and
    neo-formed jarosites from spoil and riverine hinterlands results in an annual cycle of rapid
    metal and acidity transference from CA spoil and Tintillo headwaters to the downstream
    environment. The high affinity of jarosites for heavy metals and the capacity of watersoluble
    evaporites to coprecipitate, adsorb and/or scavenge a suite of toxic metals
    (including Co, Cu, Mn, Zn, Ni and Cd) result in geomorphological and secondary mineral
    interfaces that are major and dynamic conduits for metal transport within and through the
    system, particularly during flood events.
    Date of Award2017
    Original languageEnglish
    Awarding Institution
    • University of Brighton
    SupervisorAndrew Cundy (Supervisor)

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