Environmental Aspects of Phosphate and Potash Mining United ...

Beneficiation
The Environmental Approach of the Phosphate Rock and Potash Mining Industry
24
Water Contamination
Water contamination may occur through spillage of
ore slurries or brines from pipelines and the mobilization
of fines by rain run-off from roads or stockpiles.
The effects of slurry pipeline spillages are reduced
through the use of monitoring and containment techniques.
Automated monitoring systems allow
management to be notified in a timely manner in the
event of a failure. Earth walls and double-lined pipes
contain and reduce the extent of the spill until remedial
action can be taken.Soil and groundwater
contamination may also result from the spillage of
brines.
Fines generated from heavy vehicle traffic on unsealed
roadways and from stockpile areas may contaminate
run-off water. The fines can be contained by the use of
techniques like silt traps and sediment retention dams.
Methods are discussed further in Section 3.3,
“Excavation”.
Noise
Heavy vehicles and equipment use can generate significant
noise, sometimes around the clock, affecting the
well-being of neighboring communities. The impact is
reduced by the careful location of roads, use of noise
barriers or buffer zones, sequencing of mining operations
and restricting the operating hours of the
equipment.
Slurry pipelines address this concern, as they produce
little noise.
3.5 Beneficiation and Concentration
Beneficiation and concentration may adversely affect
the environment by:
The generation of wastes such as sand, magnetite
and salt tailings, clay fines and brines;
The consumption and contamination of large volumes
of fresh water during processing with fines,
chemical reagents, and brines;
The emission of dust from processing operations
such as crushing and drying;
The emission of exhaust particulates and gases
during the generation of electrical power and the
drying of product.
Other potential impacts include noise and vibration
produced by equipment such as rock breakers, crushers
and grinding mills.
Figure 3.5.1
Potential environmental effects : beneficiation
Size reduction
(crushing, grinding,
screens, cyclones)
Separation,
concentration and
contaminant removal
Drying, compaction,
granulation, etc...
Waste Generation
Waste generation
Water consumption
Water contamination
Air emissions
Noise and vibration
Resource maximization
Product transported
to further processing,
distribution and use
The large volumes of waste generated during beneficiation
of phosphate rock and potash may potentially
cause adverse environmental effects. The volume and
type of wastes will depend on the ore characteristics
(ore grade, constituent minerals, and contaminants),
in addition to the specific beneficiation process
employed.
A variety of wastes is generated from the beneficiation
of phosphate rock, and may include:
Oversize low-grade rock from screening;
Coarse tailings composed of sand;
Fine tailings composed of clays and similar size
materials;
Process water contaminated with fines and process
reagents.
In some instances, magnetite tailings have also be generated.
The beneficiation of potash produces wastes such as:
Tailings consisting largely of impure salt (NaCl)
with smaller amounts of other minerals such as
anhydrite;
Slimes consisting of insoluble fines such as clay
and dolomite;
Brines containing salt or magnesium chloride.
In most countries, wastes are disposed of to specially
engineered impoundments such as dams and ponds
or released in a controlled manner to the environment.
Disposal methods are discussed in detail in
Section 3.7 “Waste Management and Disposal”.