- The document discusses various types of mine waste and methods for their disposal, with a focus on tailings. - Tailings consist of finely ground rock particles in a liquid slurry that is usually stored in engineered structures called tailings storage facilities or tailings dams. - Tailings dams aim to safely contain tailings and their chemical byproducts indefinitely while minimizing contamination of surface and groundwater. - Alternative disposal methods directly release tailings into rivers, lakes or oceans but risk long-term pollution if not properly treated or neutralized first.

1. TAILINGS
@Hassan Harraz 2020
TAILING
Hassan Z. Harraz
hharraz2006@yahoo.com
Spring 2020
Sukari TSF

2. ❑ MINES WASTES: Types of mine waste
❑ WASTE-ROCK DISPOSAL (ROCK DUMPS)
❑ WASTEWATER
❑ TAILINGS & TAILINGS COMPOSITION
➢ Tailings Solids
➢ Tailings waters
i) Sulphidic mine wastes
ii) Acid Mine Waters
❑ TAILINGS DISPOSAL METHODS
➢ Dynamic Simulation of a Tailing Storage Facility (TSF)
➢ Tailings Dam Styles (or Configurations)
➢ Fundamental Constructed Elements of a Tailings Dam
➢ Water Balance of a Tailings Dams
❑ DISPOSAL METHODS:
THICKENED DISCHARGE AND PASTE DISPOSAL
IN-PITWASTE DISPOSAL
SEEPAGE FLOW TO SURFACE WATER AND GROUNDWATER
RIVERINE TAILINGS DISPOSAL
SUBMARINE TAILINGS DISPOSAL
❑ ALTERNATIVE LOCATION TO TAILING
Outline of Topic:

4. ❑ Mine wastes are problematic because they contain hazardous
substances that can be (or are) released into the environment
around the mine – heavy metals, metalloids, radioactive
elements, acids, process chemicals – and therefore require
treatment, secure disposal, and monitoring.
❑ Wastes are not only produced during mining, but also at
mineral processing plants and smelter sites and include
effluents, sludges, leached ore residues, slags, furnace dusts,
filter cakes and smelting residues.
❑ Mine wastes may be in the form of: solid waste, water waste, or
gaseous waste.
❑ Environmental contamination and pollution as a result of
improper mining, smelting and waste disposal practices has
occurred, and still occur, around the world (Lottermoser, 2007).
1) MINES WASTES

6. 1) MINE WASTES:
Open-pit mining
Underground mining
Produces waste rock:
either
➢Barren Host Rock , or
➢ “Ore” that is too low-grade, overburden soils
and sands.
Mineral processing
Hydrometallurgy
▪ Produces processed solid wastes that includes:
tailings and sludges with different physical and
chemical properties.
▪ Tailings can be used as mining back-fill, but are
generally contained on surface.
▪ Also produces mill-water and other processing
waste-water also produced, as well as
atmospheric emissions.

7. ❑ Waste-rock is always produced at an open pit mine and rarely, if ever,
produced at an underground mine.
❑ “Waste-rock” is rock emerging from the mine that will not be processed further.
It is either “ore” that is below the cut-off grade, or is simply the barren
host-rock to the mineral deposit.
❑ Rock dumps contain an wide variety of different rocks and minerals that
is site specific, depending on the nature of the ore deposit and the host-rock.
If sulphide minerals are present in any of the rocks, there is the potential for
Acid Mine Drainage.
➢ Generally rock dumps are not sealed at their base, and the risk of acid
water incursion into the surface drainage system or subsurface aquifers is
very high.
❑ Dumping must be managed because uncontrolled dumping can be dangerous.
✓ Water flowing through a dump must also be controlled to maintain stability
and prevent contaminating surface water or groundwater.
✓ Rock dumps are also highly porous to water flow, and therefore
increases significantly the risk of AMD production.
❑ The operation and management of a waste dump are affected by the mine
plan, i.e., the geometrical relationship between waste and ore in the mine and
the strip ratio.
2) WASTE-ROCK DISPOSAL (ROCK DUMPS)

8. Trucks (the size of houses) dump 200-ton loads of waste rock from an open pit mine in
Nevada. A composite storage approach is used here: top-down dumping is following after
an earlier phase of bottom-up dumping.
http://science.nationalgeographic.com/science/enlarge/dumping-waste-rock.html
Rock dumpsTop-down storage: waste
rock is dumped over an
advancing face.
Bottom-up storage:
waste rock is
dumped in a series
of piles, and later
spread out and
flattened, to be
covered by the next
layer of dumping.

9. Typically a “plume” of contaminated water (either acidic or not) and
precipitated waste products is developed below and around a rock dump.
Schematic cross-section of a sulphide waste dump showing a plume of acid water
seeping into the ground. Also shown is how various subsurface minerals (at this
particular site) help to buffer, or neutralise, the acid. The initial highly acidic pH
value of 1, directly below the dump, is buffered back to a neutral pH value of 7 at
some depth below the dump.
Figure from Lottermoser, 2007, reproduced from Jurjovec et al., 2002.
Potential for lateral
migration of
contaminated or acidic
water within subsurface
aquifers
2) WASTE-ROCK DISPOSAL (ROCK DUMPS)…..(Cont.):
Sulfidic waste

10. ❑ Tailings consist of a Liquid and Solid Component: generally about 20 –
40 weight percent solids (Robertson, 1994).
✓The composition of both is highly site-specific, depending on the
ore and gangue minerals and the nature of the water (fresh or saline)
and processing chemicals used.
i) Tailings waters may be Alkaline (Cyanide used in processing), Acidic
(Sulphuric Acid used in processing) or Saline (Saline Water used in
processing). They are a complex cocktail of residues of the processing
chemicals. The waters are highly chemically reactive.
ii) Tailings solids are:
✓finely ground rock from the mill
✓particles ≤ 0.1 mm in diameter (sand and silt)
3) TAILINGS & TAILINGS COMPOSITION

11. 3.1) Solid Tailings
❑ In mining and mineral processing, materials
are separated according to their particle
size and mineralogy
❑ The wastes produced fall into
➢ Coarse-grained (waste/rejects); &
➢ Fine-grained (tailings)
❑ Tailings:
➢ Rock flour resulting from the crushing
and or grinding of mine ore ;
➢ Finely ground rock from the
concentrator/processing plant.
➢ Particles ≤ 0.1 mm in diameter (sand
and silt).
❑ Conventionally disposed of separately
Co-disposal involves the combining of
these waste streams
Figure from Lottermoser, 2007.
GRAIN SIZES OF SOLIDS

12. 3.2) Waste Water (or Liquid Waste)
❑ Waste water consists of liquid wastes from processing:
➢Flotation Reagents, SX/EW solvents and
➢Acids or Cyanide used in leaching processes:
✓Alkaline (Cyanide used in processing),
✓Acidic (Sulphuric Acid used in processing) or
➢Saline (Saline Water used in processing).
❖They are a complex cocktail of residues of the processing
chemicals. The waters are highly chemically reactive.
❑ Waste water from a mine may contain:
➢ ammonia from explosives
➢ contaminated groundwater
❑ Something has to be done about waste water. The best
strategy is to minimize the production of waste water but this
usually leads to higher costs. It could be contained, as in
behind a dam, but this is difficult and risky. Usually it is
treated and reused or discharged to the environment.

13. ❑Sulphide wastes are the biggest problem on mines because of potential
for generating acid mine waters. Pyrite is the major concern.
❑Sulphide minerals occur abundantly in many types of deposits:
❖ Metallic ore (Cu, Pb, Zn, Au, Ni, U, Fe)
❖ Phosphate ores
❖ Coal seams
❖ Oil shales
❖ Mineral sands
❑Sulphide minerals may be exposed (just about) everywhere in mines:
❖ Tailings dams
❖ Waste rock dumps and coal spoil (overburden) heaps
❖ Heap leach piles
❖ Run-of-mine and low-grade ore stockpiles
❖ Waste repository embankments
❖ Open-pit floors and faces
❖ Underground workings
❖ Haulroads and road cuts
i) Sulphidic Mine Wastes:

14. “Acid mine drainage” (AMD) refers to a particular
process whereby low pH mine water is formed from
the oxidation of sulphide minerals. It provides one
of the most significant hydrological impacts of mining.
AMD is particularly prevalent in both metallic mineral
and coal mines.
Some authors refer to “Acid rock drainage” (ARD), “Acid
sulphate waters” (ASW); and also “Acidic ground
water” (AG) when referring to impacted ground-water
specifically.
ii) Acid Mine Waters:

15. ❑ Tailings are (generally) stored in engineered structures or impoundments,
called “Tailings Storage Facilities” (TSF) or “Tailings Dams” (TD).
➢ It is estimated that there are at least 3,500 tailings dams worldwide
(Davies and Martin, 2000).
❑ Tailings dams (TD) should be constructed to:
➢Contain waste materials indefinitely, and provide long term stability
against erosion and mass movement.
➢Achieve negligible seepage of tailings liquids into ground and surface
waters to prevent contamination of these waters.
➢Prevent failure of dam structures.
❑ The overriding issue with tailings dams is getting the liquid out of
them, safely, both during mining and afterwards.
❑ In an alternative disposal approach (that is often highly criticised), no
impoundment is used at all, and tailings are pumped directly into rivers
(Riverine Tailings Disposal), lakes (Lacustrine Disposal) or into the
ocean and onto the seafloor at some water (Submarine Tailings Disposal
– STD).
4.2) Tailings Disposal Methods ..(Cont.)4) TAILINGS DISPOSAL METHODS

16. 4) TAILINGS DISPOSAL METHODS ….(Cont.)

17. 4.1) Dynamic Simulation of a Tailing Storage Facility (TSF)

18. 4.2) Tailings Dam Styles (or Configurations)

19. Tailings dams hold up to several hundred million cubic meters of water
saturated tailings – they can be very, very large structures.
❑ The fundamental constructed elements of a tailings dam are:
➢ Dam walls (dykes) to contain the tailings. These are normally
constructed using waste rock and material available at the dam site.
The maximum wall height is reported currently to be about 100 m.
➢ Impermeable liners at the base of the dam to prevent leakage of fluids.
Linings may consist of geomembranes (polyethylene or PVC), or clay
layers, or a combination of the two.
➢ Drainage ditches around the periphery of the tailings dam to collect
seepage.
➢ Under-drains to facilitate drainage and consolidation of the tailings in
the dam. (Not all tailings dams have under-drains installed). Without
under-drains, tailings dams can only dry-out by evaporation and
seepage, which generally takes a long time (years after mining has
ceased).
4.3 ) Fundamental Constructed Elements of a Tailings Dam

20. Tailings dam at Chatree
Gold Mine (Thailand) shortly
after commissioning, showing
under-drains installed in a
herring-bone pattern.
Under-drains significantly
improve water drainage from
the tailings dam, thereby
reducing water saturation of
tailings sediments and
improving geotechnical
strength and safety of the
dam.
Figure from Spitz and Trudinger, 2009.
(i) drains beneath the dam walls,
(ii) double liners under the dam, with a leak detection system between layers,
(iii)under-drains at the base of the tailings and a liquid recovery system.
Best practice tailings dam construction will consist of:
4.3 ) Fundamental Constructed Elements of a Tailings Dam….(Cont.)

21. Mature, but active,
tailings dams located
south of
Johannesburg, South
Africa. These dams
are receiving the final
tailings products of
the reprocessing of
numerous old mine-
dumps spread around
Johannesburg. The
mines were closed in
the 1960s.
http://www.panoramio.com/photo/2399572
4.3 ) Fundamental Constructed Elements of a Tailings Dam…(Cont.)

22. 4.3 ) Fundamental Constructed Elements of a Tailings Dam…(Cont.)

23. Downstream construction
Upstream construction

24. 4.3) Fundamental Constructed Elements of a Tailings Dam…(Cont.)

25. 4.4) Water Balance of a Tailings Dams

26. Thickened Tailings
Figure 1: Thickened discharge at Kidd Creek, ON, Canada (left) and at Mt
Keith, Western Australia (right)

27. 5) THICKENED DISCHARGE AND PASTE DISPOSAL
PLAN VIEWAIR-PHOTO
Thickened tailings
are discharged
from central “riser”
and a series of
outer risers to
create a set of
cone shaped
impoundments.
The “risers” are
moved up
incrementally as
the layers of
tailings material
build up.
Figure is greatly
vertically
exaggerated:
the slope of
“beaches” is
only 1 to 3
1 – 3
Figure from Spitz and Trudinger, 2009.

28. See e.g., Williams and Seddon, 1999; Brzezinski, 2001.
Advantages over conventional tailings disposal are that:
(i) The disposal site covers a much smaller surface area,
(ii)tailings are not segregated into coarse and fine components, which
improves the geotechnical properties of the pile,
(iii)water consumption is significantly reduced,
(iv)process chemicals are recovered with the water, rather than left with the
tailings,
(v)contaminated water drainage into the subsurface and surface water
systems is reduced,
(vi)The resulting cone shaped deposit provides an attractive landform (say the
miners!), more amenable to rehabilitation.
Disadvantages of the method include:
(i) The operations are subject to dust generation,
(ii)failure due to liquefaction is not ruled out entirely during the period
required to dry the paste (McMahon et al., 1996).
Thickened discharge disposal – advantages and disadvantages:

29. 29
Example
Thickened tailings
deposited into pit
pond
Waste rock end-dumped
into pit

30. Sukari Gold
Project; Eastern
Desert-Egypt

31. hharraz2006@yahoo.com
TSF
View of Sukari Pit Disposal Tailings
Waste rock
Tailing beach

32. hharraz2006@yahoo.com
Sukari Pits Disposal Tailings
32
Thickened tailings
Waste
TSF
TSF
TSF

33. hharraz2006@yahoo.com
General view of Sukari mine site
Waste
TSF
TSF

34. 6) IN-PITWASTE DISPOSAL

35. Figure 1: Typical in-pit tailings storage

36. SEEPAGE FLOW TO SURFACE WATER AND GROUNDWATER
Seepage to surface water
and groundwater may
lead to surface water and
groundwater
contamination in the
short- medium- and long-
term. The facility needs to
be adequately located and
designed and the relevant
seepage control measures
need to be in place
according to the
characteristics of the
managed tailings in order
to minimize
contamination of surface
and groundwater.
Figure illustrates schematic seepage
flow scenarios for different types of
tailings facilities.

37. ❑ Riverine tailings disposal is currently used in more than a few modern
mining projects, e.g., the copper mines at:
➢ Grasberg-Ertsberg, Indonesia
➢ Porgera, Papua New Guinea
➢ Ok Tedi, Papua New Guinea
➢ Bougainville (closed), Papua New Guinea
❑ Riverine disposal is “preferred” in these areas because earthquakes,
land-slides and very-high rainfall makes the construction of tailings dams
geotechnically “impossible”.
❑ Miners argue that high natural sediment loads in rivers, generated by the
high rainfall, is able to dilute the mine tailings discharges. (Nonsense –
tailings volumes are huge compared to the natural sediment load).
❑ Tailings can be neutralized before disposal into the river systems (but they
are not always).
❑ Historically: riverine tailings disposal from mines was commonly
practiced.
7) RIVERINE TAILINGS DISPOSAL:

38. ❑ The solids and liquids of tailings are transported down rivers for considerable
distances: tens to hundreds to thousands of kilometers.
❑ Sulphide minerals in discharged tailings generally oxidize in oxygenated river
waters, creating the potential for acidification of waters.
❑ Problems include:
➢ Significantly increased sedimentation and turbidity in the river system,
and associated flooding of lowlands.
➢ Contamination of the stream and floodplain sediments with metals, and
associated impact on aquatic ecosystems.
➢ Diebacks of rainforests and mangrove swamps.
7.1) Riverine tailings disposal – impacts:

39. 8) SUBMARINE TAILINGS DISPOSAL
Figure from Spitz and Trudinger, 2009.
Greater
than 50 m
water
depth
De-aeration and mixing with
seawater to increase density
of slurry
Coagulants and flocculants
used to bind particles together
to form a thicker mixture to
prevent wide dissemination of
the tailings-plume underwater
Plume of lighter
tailings material
Final resting place
of tailings on the
sea-floor
The euphotic layer is defined as
the depth reached by only 1% of
photosynthetically active light
(High density
polyethylene)

40. ALTERNATIVE LOCATION TO TAILING

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@Hassan Harraz 2020
TAILINGS