Passive Neutralization of Acid Mine Drainage Using Locally Produced Limestone

Neutralisation of acid-mine drainage (AMD) using limestone is cost effective, and good results can be obtained. However, this process has its limitations; it cannot be used for highly acidic water which consists of Fe(III). When Fe(III) reacts with CaCO₃, it results in armoring. Armoring slows the reaction, and additional alkalinity can no longer be generated. Limestone is easily accessible, so this problem can be easily dealt with. Experiments were carried out to evaluate the effect of PVC pipe length on ferric and ferrous ions. It was found that the shorter the pipe length the more these dissolved metals precipitate. The effect of the pipe length on the hydrogen ions was also studied, and it was found that these two have an inverse relationship. Experimental data were further compared with the model prediction data to see if they behave in a similar fashion. The model was able to predict the behaviour of 1.5m and 2 m pipes in ferric and ferrous ion precipitation.

• Reneiloe Seodigeng
• Malwandla Hanabe
• Haleden Chiririwa
• Hilary Rutto
• Tumisang Seodigeng

• Acid mine drainage
• neutralization
• limestone
• modeling.

[1] Hammarstrom, J. M., Sibrell, L. P., and Belkin, H. V., 2003. Characterisation of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA.
[2] Louis, R.B., Aubertin, M., Poirier, C., and Bussiere, B., 2002. On the use of limestone drains in the passive treatment of acid-mine drainage. Montreal, Canada.
[3] Engelbrecht, A.D., 2007. Investigation into the gasification characteristics of South African power station coals, CSIR, Pretoria, South Africa.
[4] Schmid, K. L., Sharpe, W. E., 2002. Passive treatment methods for acid water Pennsylvania. PennState college of Agricultural Science Agricultural Research and Cooperative Extension.
[5] Ziemkiewics, P., Skousen, J., and Lovett, R., 1997. Acid-mine drainage treatment with armored limestones in open limestones channels. J. Environ. Qual. 26: 1017-1024.
[6] Rutto, S., Maree, J.P., Zvinowanda, C.W., Louw, W.J., and Koslesnikov, A.V., 2011. Thermal studies on gypsum in a pilot-scale, rotary kiln. Proc. Water in the South African institute of mining and metallurgy, 01-06 March 2015.