Integrating Nano Iron Production into the Acid Mine Drainage Neutralisation Treatment Process

The emission of acid mine drainage (AMD) from mine workings and waste impoundments is of particular concern in South Africa, especially in the Witwatersrand gold fields and the Mpumalanga coal fields. One potentially valuable iron-product that could be recovered from iron-rich AMD, is zero-valent iron in the nanoparticle size range (<100 nm), also known as zero-valent nano iron (ZVNF). Zero-valent nano iron offers a number of advantages over micro- and macro-iron in water treatment applications due to its high reactivity, and is traditionally prepared from ferric chloride using chemical reductants, such as sodium borohydride, or polyphenolic compounds extracted from green plants such as lemon, grape, sorghum, etc. It is, furthermore, postulated that the pre-removal removal and recovery of iron from AMD in the form of nano iron also provides the opportunity to generate a purer, and potentially more valuable, gypsum product during subsequent lime neutralisation.

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