Tailings Disposal - Mining and the Environment: From Ore to Metal - page 727

TABLE 18.3
Comparison of Different Pulp Density and Disposal Methods - Along the continuum of slurry,
thickened, paste, dry tailings and fi nally cemented tailings, the solids contents and costs of production increase

Pulp Density/Disposal method Advantages Disadvantages

Slurry (Conventional) Low capital costs

Low dewatering and operation costs
Easy to pump

Large storage volume required
High environmental risk
Large water handling
High embankment costs
Diffi cult to rehabilitate slimes
Challenging post-mine care

Thickened Less storage volume required

Low dam construction cost
Reduced seepage

Increased dewatering costs
High capital costs
High pumping costs
Large surface area

Paste Less storage volume required

Low dam construction cost
Large beach area maximizes tailings
density and strength
Minimized seepage

Increased dewatering costs
High capital cost
High pumping costs

Dry Minimum storage volume required

Lower seismic risk
Surface compaction possible
Recycling of process chemicals
Minimized seepage
Co-disposal with waste rock
Progressed rehabilitation

High capital cost
High transport costs

Cemented No or small dams required

Erosion resistance
Seismically stable

Very expensive
Diffi cult to transport

of i ne particles or slimes. Due to this segregation of particle sizes, tailings characteris-
tics such as strength, permeability and shrinkage vary laterally across a TSF.

●

Large changes in TSF operating regime typically occur during the production phase.

●

After mining the TSF must remain as safe as during mine operations.

●

Tailings storages are designed to contain or to control actual or potential contamination.

Tailings Pulp Density

Tailings pulp density and strength increase as water content is reduced. This can be managed
at a cost: tailings come as slurry, thickened, pasted, dry and cemented tailings. Table 18.3
summarizes how tailings pulp density inl uences tailings disposal.
Disposal of tailings as an un-thickened slurry (termed wet tailings) is the most common
form of tailings disposal. In this method, tailings slurry is pumped from the process plant
to an impoundment where the tailings undergo sedimentation, consolidation and desicca-
tion. The embankments are designed to retain both water and solids.
There is considerable confusion in the mining industry regarding the dei nition of
thickened and paste tailings. Thickened tailings imply high density slurry while the lat-
ter refers to the paste-like and non-segregating nature of tailings. In these methods the

Disposal of tailings as an
un-thickened slurry (termed wet
tailings) is the most common
form of tailings disposal.