An Aspen Model for the Treatment of Acid Mine Water

R.E. Damons and F.W. Petersen*

Department of Chemical Engineering, Cape Technikon, PO Box 652
Cape Town, 8000, South Africa

Received 6 February 2002; accepted 25 May 2002


Although numerous methods exist to treat acid mine water they all have inherent disadvantages. A means of treating acid mine drainage is by forming a precipitate known as ettringite. Ettringite is a low solubility calcium hydrosulphoaluminate that is stable between pH values of 11.4 and 12.4. Ettringite is made up of calcium, sulphate, aluminium and a large amount of water. Decomposition of ettringite takes place by dropping the pH to about 7. A 5 stage process is proposed to treat acid mine drainage of which the formation of ettringite forms the cornerstone of this process. The process incorporates the formation of more than one precipitate as well as the recycling of aluminium hydroxide when ettringite is decomposed. The results obtained in this paper are as a result of modeling this process. The modeling of this process was performed on a computer simulation package known as Aspen

Keywords: acid mine drainage; ettringite; model

* Corresponding author
   E-mail : fwp@ctech.ac.za