Selective removal of arsenic from acid mine drainage containing ferrous ion using sulfide precipitation method

Chiharu Tokoro, K. Sunada, D. Dai, G. Dodbiba, T. Fujita, A. Onishi, S. Nagasawa, H. Asano, K. Hashimoto

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Selective removal of dilute arsenic ions (As(III) or As(V)) from acid mine drainage (AMD) containing ferrous irons was investigated using a sulfide precipitation method. 10 mg/dm3 of As(III) could be removed as As2S3 at pH ≥ 2.0 in a NaSH solution, which S/As ratio was higher than6.5 after 0.5 hr of reaction time. H2S gas generation correlated with the residual As(III) concentration in AMD. Below pH 2.5, ferrousions were not found in the sludge and thus selective removal of As(III) was achieved. On the other hand, at pH 2.5, a NaSH solution of S/As ≥ 40 and a reaction time of 24 hr were required to remove 10 mg/dm3 of As(V). However, at pH3, 10 mg/dm3 of As(V) could be removed after 0.5 hr of reaction time by using a NaSH solution of S/As ≥ 6. Nevertheless, around 1/3 of ferrousions were oxidized and removed as ferrihydrate together with As(V). EXAFS analysis showed that As(V) was adsorbed on ferrihydrate when S/As ratio was 7, but precipitated as As2S3 at pH3, when S/As ratio was 20. These results showed that reduction of As(V) to As(III) was very slow and needed enormous amount of sulfurising agent and relatively long reaction time. The average primary diameter of the particles in the sludge was under 900 nm, which was increased with increasing dosage of NaSH. Particles exhibited a negative zeta potential of small value, which indicates that they could coagulate to each other. Therefore, sedimentation rate of the particles from sulfide precipitation method was better than the one from conventional hydroxide co-precipitation method using calcite or lime. Sedimentation of As(V) sulfide particles at pH3 occurred at a very fast speed because a small amount of ferrihydrite co-precipitated with As(V) sulfide, which acted as a coagulant.

    Original languageEnglish
    Title of host publicationXXV International Mineral Processing Congress 2010, IMPC 2010
    Pages3965-3973
    Number of pages9
    Volume5
    Publication statusPublished - 2010
    Event25th International Mineral Processing Congress 2010, IMPC 2010 - Brisbane, QLD
    Duration: 2010 Sep 62010 Sep 10

    Other

    Other25th International Mineral Processing Congress 2010, IMPC 2010
    CityBrisbane, QLD
    Period10/9/610/9/10

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    Keywords

    • Arsenic
    • Sedimentation rate
    • Sulfide precipitation
    • Wastewater treatment

    ASJC Scopus subject areas

    • Earth-Surface Processes
    • Geology
    • Electrical and Electronic Engineering
    • Mechanical Engineering

    Cite this

    Tokoro, C., Sunada, K., Dai, D., Dodbiba, G., Fujita, T., Onishi, A., Nagasawa, S., Asano, H., & Hashimoto, K. (2010). Selective removal of arsenic from acid mine drainage containing ferrous ion using sulfide precipitation method. In XXV International Mineral Processing Congress 2010, IMPC 2010 (Vol. 5, pp. 3965-3973)