Fe OXYHYDROXIDES AS A REMEDIATION AGENT FOR CONTAMINATED MINE WATERS

2019 ◽  
Author(s):  
Ondrej Brachtyr
Keyword(s):  
Mine Waters ◽  
Fe Oxyhydroxides

scholarly journals Mobilisation and Bioavailability of Arsenic Around Mesothermal Gold Deposits in a Semiarid Environment, Otago, New Zealand

2002 ◽  
Vol 2 ◽  
pp. 308-319 ◽  
Author(s):  
D. Craw ◽  
L. Pacheco
Keyword(s):  
New Zealand ◽  
Vadose Zone ◽  
Surface Waters ◽  
Gold Deposits ◽  
Processing Plant ◽  
Geological Time ◽  
Iron Oxyhydroxides ◽  
Mine Waters ◽  
Evaporative Concentration ◽  
Fe Oxyhydroxides

Arsenopyrite (FeAsS) is the principal arsenic (As) mineral in mineralised mesothermal veins (typically 5,000 mg/kg As) in southeastern New Zealand. Groundwater in contact with arsenopyrite-bearing rocks has elevated As concentrations (up to 0.1 mg/l). The arsenopyrite decomposes slowly on oxidation in soils and historic mine workings in a cool semiarid climate. Dissolved As is predominantly As(III) in association with arsenopyrite, but this is rapidly oxidised over days to weeks to As(V) in the vadose zone. Oxidation is facilitated by particulate Fe and/or Mn oxyhydroxides, and by bacteria in surface waters. Evaporative concentration of dissolved As(V) in the vadose zone causes precipitation of scorodite (Fe(III)As(V)O4.2H2O). Adsorption of As(V) to Fe oxyhydroxides in soils and groundwater pathways lowers dissolved As concentrations. Soils over mineralised veins typically have <200 mg/kg As, as most As is removed in solution on geological time scales. Most plants on the mineralised rocks and soils do not take up As, although some inedible species can fix up to 18 mg/kg As. Hence, bioavailability of As(V) is low in this environment, despite the substantial As flux.Similar As mobility is seen in an active gold mine processing plant and tailings. Arsenopyrite dissolves more rapidly on agitation, and mine waters can have dissolved As >200 mg/l, predominantly as As(V). This dissolved As decreases in tailings waters to near 2 mg/l, mainly as As(III) when in contact with arsenopyrite. Weak oxidation of evaporatively dried tailings causes cementation with scorodite and iron oxyhydroxides, and scorodite precipitation exerts some control on dissolved As(V) concentrations. High dissolved As in mine waters is lowered by adsorption to iron oxyhydroxides, and waters discharged from the mine site have negligible dissolved As.

scholarly journals Effect of pedogenic iron-oxyhydroxide removal on the metal sorption by soil clay minerals

2021 ◽  
Vol 21 (4) ◽  
pp. 1785-1799
Author(s):  
Péter Sipos ◽  
Viktória Kovács Kis ◽  
Réka Balázs ◽  
Adrienn Tóth ◽  
Tibor Németh
Keyword(s):  
Clay Minerals ◽  
Close Association ◽  
Direct Analysis ◽  
Alkaline Soil ◽  
Mineral Surfaces ◽  
Iron Oxyhydroxide ◽  
Metal Sorption ◽  
Before And After ◽  
Fe Oxyhydroxides ◽  
Cu And Zn

Abstract Purpose The close association of Fe-oxyhydroxides and clay minerals might influence the sorption properties of these components. We aimed to study the effect of removing the pedogenic Fe-oxyhydroxides on the sorption of Cd, Cu, Pb, and Zn by the clay mineral particles in soils with contrasting pH. Methods Competitive batch sorption experiments before and after Fe-oxyhydroxide extraction in soils were carried out together with the direct analysis of the metal sorption on individual particles of ferrihydrite, smectite, and illite/smectite by TEM. Results Ferrihydrite was a more effective metal sorbent than clay minerals, although its removal resulted in decreased sorption only for Cd, Cu, and Zn. Ferrhydrite coating blocked metals’ access for certain sorption sites on clay surfaces, which were only accessible for Pb as the most efficient competitor after removing the coating. This observation was the most remarkable for the smectite particles in the alkaline soil. Mineral surfaces sorbed higher Cu than Pb concentrations and higher Zn than Cd concentrations despite the former metals’ lower bulk sorption. Thus, organic surfaces and precipitation contributed to Pb and Cd’s retention to a greater extent than for Cu and Zn. The structural Fe of smectite also promoted the metal sorption in both soils. Conclusion Removal of iron-oxyhydroxide coatings from the soil affects metal sorption selectively. Direct study of metal sorption on individual soil particles enables us to gain a more in-depth insight into soil minerals’ role in this process.

Impact of the Discharge of Salinised Coal Mine Waters on the Structure of the Macroinvertebrate Communities in an Urban River (Central Europe)

2019 ◽  
Vol 231 (1) ◽  
Author(s):  
Dariusz Halabowski ◽  
Iga Lewin ◽  
Paweł Buczyński ◽  
Mariola Krodkiewska ◽  
Wojciech Płaska ◽  
...  
Keyword(s):  
Central Europe ◽  
Coal Mine ◽  
Urban River ◽  
Macroinvertebrate Communities ◽  
Mine Waters
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