Environmental Aspects of Phosphate and Potash Mining United ...

Environmental Aspects of Phosphate and Potash Mining
ways, during loading and unloading operations, at
conveyor transfer points and during the stacking of
stockpiles and reclamation operations. Exhaust gases
and particulates are largely produced by the operation
of transport.
A variety of dust control techniques are used, as discussed
in Section 3.1.
Equipment emissions are reduced by the use of
exhaust filters, regular equipment maintenance programs
and replacing old engines with new, more
efficient and cleaner models.
Watershed Protection
Regulations in Florida to protect watersheds from disturbance
have restricted the development of
floodplains, streams and rivers. Accordingly, phosphate
rock mining operations must establish buffer
zones and work around these features. However, on
occasions crossings may have to be constructed
across them to facilitate access to mining areas.
Development of a new mining area at the IMC
Phosphate Four Corners operation in central Florida
required the construction of a river crossing. This was
designed to allow vehicle and equipment access and
the passage of several large diameter slurry pipelines
between the mining area and the beneficiation plant.
The design has a number of features to mitigate
potential environmental impacts.
Culverts have been placed under the earthen vehicle
crossing, allowing normal river flow to be maintained.
Silt traps contain minor erosion sediments from the
crossing.
During heavy rain, the water level rises and passes
over the crossing. Surfacing the vehicle roadway with
coarse aggregate and the planting of grass on adjacent
roadside areas has reduced the potential for
erosion.
The large-diameter ore slurry pipelines have been
placed alongside the crossing roadway and elevated
to allow water to pass underneath. In the event of failure,
the pipes are double lined at the crossing,
discharging to a containment pond at one end, while
an automated monitoring system alerts management.
Watershed protection is an integral part of the crossing
design. The construction of a stable, non-eroding
river crossing and the installation of a monitoring and
containment system in the event of a slurry pipeline
failure prevent contamination of downstream areas.
Transport of Ore and Concentrate by Slurry
Pipeline
The transport of ore and concentrates as a slurry (a
mixture of water and ore particles in suspension) has
benefits such as less road transport congestion,
reduced vehicle exhaust emissions and the elimination
of sources of dust emission. Slurry pipelines are
used at a number of operations worldwide.
In Florida, the phosphate mining operations of companies
such as Cargill Fertilizer Inc. and IMC
Phosphate use high-pressure water jets to convert the
ore excavated by the draglines into a slurry which can
be pumped to the beneficiation plants through large
diameter pipelines.
In Brazil, Fertilizantes Fosfatados S.A. (Fosfertil) uses a
125 kilometre long pipeline to transport phosphate
rock concentrate slurry from the beneficiation plant at
the Tapira mining complex to the fertilizer processing
complex at Uberaba.
Uberaba Fertilizer processing complex - Fosfertil, Brazil
Phosphate rock concentrate slurry tanks and pumping -
Fosfertil, Brazil
Slurry pipelines require significant quantities of water.
This may present issues in areas of limited resources.
Recycling or re-use of the water for other processes
may be possible.