Geochemical modelling, iron precipitates

[Andy Barnes]

Does anyone know what are appropriate Saturation Indices to use to control the precipitation of the iron minerals goethite, and H, K and Na jarosite in PhreeqC.

At the moment I am only using ferrihydrite as the controlling mineral phase for iron in calculations. This is fine under circum-neutral to mildly acidic pH conditions but does not account for precipitation under more acidic - high sulfate conditions. In addition, using a SI of 0 for goethite or jarosite minerals produces a very low dissolved iron concentration (that does not match up with field observations).

I assume that the thermodynamic controls in the Minteq.V4 database is correct, and that there are certain kinetic controls that need to be taken into consideration with the aforementioned minerals. I assume that a poorly crystalline precursor (e.g. schwertmannite) may be controlling equilibrium concentrations under more acidic pH conditions but I have not traced down suitable thermodynamic data for this as yet.

Has anyone experienced a similar situation?

[Andy Barnes]

A quick internet search identified this, presumably unpublished paper (see URL below) by Ron Schmiermund. This gives the thermodynamic data for Schwertmannite which I am going to input into the minteq.v4 database. Over the next couple of weeks I will attempt to run some models using ferrihydrite and schwertmannite as equilibrium phases with Saturation indexes of zero and see if this gives a better comparison to observed conditions under acidic conditions.



This may give a better alternative than using jarosite and goethite phases combined with very high defined saturation indexes

[Chris Wolkersdorfer]

Regenspurg, S. (2002): Characterisation of Schwertmannite – Geochemical Interactions with Arsenate and Chromate and Significance in Sediments of Lignite Opencast Lakes. – 125 p., 42 fig., 24 tab., 9 app.; Bayreuth (Unveröff. Diss. Univ. Bayreuth).

p. 90, Tab III-2

and if you are interested in mine water related literature about Schertmannite:

Acero P, Torrentó C, Ayora C (2005) Effect of schwertmannite ageing on Acid Rock Drainage geochemistry. In: Loredo J, Pendás F. Mine Water 2005 – Mine Closure. University of Oviedo, Oviedo, 67-73.

Balkenhol R, Ludwig B, Ufer K, Jochum J, Friedrich G (2001) Pyrite oxidation in sediment samples from the German open-cut brown coal mine Zwenkau: mineral formation and dissolution of silicates. J Plant Nutr Soil Sci-Z Pflanzenernahr Bodenkd, 164(3):283-288.

Blodau C (2004) Evidence for a hydrologically controlled iron cycle in acidic and iron rich sediments. Aquatic Sciences, 66:47-59.

Caraballo MA, Rötting T, Nieto JM, Ayora C (2007) Mineralogical Characterization of a reactive Tank in a passive AMD Treatment System at Monte Romero (Iberian Pyrite Belt, SW Spain). In: Cidu R, Frau F. Water in Mining Environments. Mako Edizioni, Cagliari, 153-157.

Dinelli E, Tateo F (2002) Different types of fine-grained sediments associated with acid mine drainage in the Libiola Fe-Cu mine area (Ligurian Apennines, Italy). Appl Geochem, 17(8):1081-1092.

Dinelli E, Lucchini F, Fabbri M, Cortecci G (2001) Metal distribution and environmental problems related to sulfide oxidation in the Libiola copper mine area (Ligurian Apennines, Italy). Journal of Geochemical Exploration, 74(1-3):141-152.

Dold B (2003) Dissolution Kinetics of Schwertmannite and Ferrihydrite in Oxidized mine Samples and their Detection by Differential X-ray Diffraction (DXRD). Appl Geochem, 18(10):1531-1540.

Dold B, Fontbote L (2002) A mineralogical and geochemical study of element mobility in sulfide mine tailings of Fe oxide Cu–Au deposits from the Punta del Cobre belt, northern Chile. Chem Geol, 189:135-163.

Egal M, Casiot C, Morin G, Bruneel O, Elbaz-Poulichet F (2008) Kinetic Controls on Iron and Arsenic Precipitation in Acid Mine Drainage (Carnoulès, France). Proceedings, 10th International Mine Water Association Congress:267-270.

Gagliano WB, Brill MR, Bigham JM, Jones FS, Traina SJ (2004) Chemistry and mineralogy of ochreous sediments in a constructed mine drainage wetland. Geochim Cosmochim Acta, 68(9):2119-2128.

Hammarstrom JM, Sibrell PL, Belkin HE (2003) Characterization of Limestone Reacted with Acid-mine Drainage in a Pulsed Limestone bed Treatment System at the Friendship hill National Historical Site, Pennsylvania, Usa. Appl Geochem, 18(11):1705-1721.

Linklater CM, Sinclair DJ, Brown PL (2005) Coupled Chemistry and Transport Modelling of Sulphidic Waste rock Dumps at the Aitik mine Site, Sweden. Appl Geochem, 20(2):275-293.

Regenspurg S (2002) Characterisation of Schwertmannite – Geochemical Interactions with Arsenate and Chromate and Significance in Sediments of Lignite Opencast Lakes. Unveröff. Diss. Univ. Bayreuth, Bayreuth, 125.

Regenspurg S, Brand A, Pfeiffer S (2004) Formation and stability of schwertmannite in acidic mining lakes. Geochim Cosmochim Acta, 68(6):1185–1197.

Sánchez España J, López Pamo E, Santofimia Pastor E, Reyes Andrés J, Martín Rubí JA (2005) A geochemical and mineralogical study on the impact of acid mine drainage on the water quality of the Odiel River (Huelva, SW Spain). In: Loredo J, Pendás F. Mine Water 2005 – Mine Closure. University of Oviedo, Oviedo, 81-87.

Schwertmann U (1999) Giftfänger im Bergbauabraum – Neues Mineral: Schwertmannit. TUM-Mitteilungen der Technischen Universität München für Studierende, Mitarbeiter, Freunde, 4:29.

Schwertmann U, Bigham JM, Murad E (1995) The first occurrence of schwertmannite in a natural stream environment. Eur J Mineral, 7(3):547-552.

Schwertmann U, Fojt B (1996) Schwertmannit – ein neues Mineral und seine Geschichte. Mineralien-Magazin, Lapis, 21(5):33-34.

Singh B, Wilson MJ, McHardy WJ, Fraser AR, Merrington G (1999) Mineralogy and chemistry of ochre sediments from an acid mine drainage near a disused mine in Cornwall, UK. Clay Minerals, 34:301-317.

Twidwell LG, Gammons CH, Young CA, Berg RB (2006) Summary of Deepwater Sediment/Pore Water Characterization for the Metal-laden Berkeley Pit Lake in Butte, Montana. Mine Water and the Environment, 25(2):86-92.

Webster JG, Swedlund PJ, Webster KS (1998) Trace metal adsorption onto acid mine drainage iron oxide. In: Arehart GB, Hulston JR. Water-Rock Interaction, vol. 9. Balkema, Rotterdam u.a., 951-954.

Williams DJ, Bigham JM, Cravotta CA, Traina SJ, Anderson JE, Lyon JG (2002) Assessing Mine Drainage pH from the Color and Spectral Reflectance of Chemical Precipitates. Appl Geochem, 17(10):1273-1286.

[Andy Barnes]

An exhaustive list!