Tailings Disposal - Mining and the Environment: From Ore to Metal - page 729

Types of Layouts

Topographic conditions usually dictate the coni guration of above grade tailings storages.
As with waste rock storages, optimal storage capacity can be obtained by taking advantage
of natural depressions in the landscape. The main types of storage are ( Figure 18.8 ):
●

Topographic conditions usually
dictate the confi guration of
above grade tailings storages.

Turkey Nest or Ring Dyke storages, involving an embankment or dyke around the
complete perimeter of the facility as shown in Figure 18.9 . This layout provides the least
storage volume per unit of area, but represents the only option on l at sites. Commonly
in these situations, a series of adjacent cells are developed during the life of the project;

●

Horse Shoe storage, involving a 'U'-shaped embankment, constructed on gently slop-
ing land or at the base of a valley slope; and

●

Valley storage, in which a dam is constructed across a valley ( Figure 18.10 ). In moun-
tainous areas, such sites may represent the only available storage options. Where pos-
sible, the storage is located near the head of the valley, to minimize inl ow from the
upstream catchment area. In other situations, it may be necessary to divert water
around the storage.

Embankment Design

Most tailings retention structures are Earth or Earth and rock embankments. These range
from low, homogeneous dykes similar to many farm dams, to more elaborate zoned
embankments incorporating sealing layers, i lter zones and drainage layers. To minimize
construction costs, mine waste and even tailings themselves are used in the embankments.
To minimize capital costs, the embankments are usually raised in stages, with each stage
typically providing additional storage capacity for one to three years of tailings produc-
tion. Three approaches have been used for staged construction of tailings embankments:
(1) downstream construction, in which each increase in embankment height, involves
downstream extension of the embankment; (2) upstream construction, in which successive
layers are placed over deposited tailings; and (3) centreline construction, in which successive

To minimize capital costs, the
embankments are usually raised
in stages.

FIGURE 18.9
Tailings Impoundment at Chatree Gold
Mine (Thailand) soon after Commissioning

Under-drains have been installed in a
'herring-bone' pattern, to facilitate drainage
and consolidation of tailings.