Colin Jones and John Lamont-Black explain electrokinetic dewatering of tailings and sludge. This paper was first published in GE’s September 2006 issue.
Extremely large volumes of mine waste are produced annually and some mine tailings lagoons are among the largest geotechnical structures in the world.
Many mining operations produce extremely fine tailings that dewater very slowly under self-weight consolidation. This results in a number of problems, including potential instability if the containment system is inadequate, loss of valuable storage space because the insitu densities are very low and difficulties with rehabilitation and closure because of the compressibility and low shear strength of the tailings, even many years after deposition.
The usual method of transport of mine tailings, sometimes over considerable distances, is by pumping.
There are significant economic and technical benefits gained from dewatering tailings before disposal. These include reduced capital expenditure and operational costs of transportation by substituting conveyors for pumps; more economic use of storage space; greater stability of the tailings; and major environmental benefits associated with water recovery. However these advantages are often elusive because the materials can be very difficult to dewater.