Environmental Aspects of Phosphate and Potash Mining United ...

The Environmental Approach of the Phosphate Rock and Potash Mining Industry
Solid Waste Disposal and Water Management System with Performance Feedback
34
The Tapira mining and beneficiation complex is located
in the state of Minas Gerais, Brazil and owned and operated
by Fertilizantes Fosfatados S.A. (Fosfertil).
Phosphate rock is extracted from an igneous deposit
using an open-cut truck and shovel mining method.
Annual production is around 11 million tonnes of ore
per year. The phosphate ore is concentrated in the beneficiation
plant before transport through a slurry
pipeline to the Uberaba fertilizer processing complex.
The waste disposal and water management system
consists of five dams in total, three of which are used for
waste storage and the other two are used to clarify and
treat water before release.
The beneficiation wastes (clay fines, sand and magnetite
tailings) are disposed of into two valley-style
tailings dams, while a small dam is located adjacent to
the plant to capture any spills. Clay fines are transported
from the beneficiation plant to one of the tailings
dam through an 8-kilometre-long open canal flowing
under gravity, while the sand and magnetite are disposed
of to the other tailings dam.
Effluent releases from the magnetite and sand tailings
dam and the plant spillage dam are passed to a clarification
dam.
The fresh water dam receives the water releases from
the clarification dam and the clay fines tailing dam as
well as the natural inflow of the Ribeiro Inferno a local
stream. This dam completes the treatment/clarification
process before excess water is released to the Rio
Araguari, a major regional river.The water quality meets
Brazilian water quality standards while the release rate
is adjusted to correspond to the normal inflow of the
Ribeiro Inferno into the dam.
The company has chosen to locate the fresh water
intake for the beneficiation plant at the release point of
the fresh water dam. Performance of the beneficiation
plant is sensitive to water quality with any deterioration
imposing a cost on the company in terms of reduced
product recovery.
The water management system lends itself to improved
performance through the built-in positive feedback
loop. This is consistent with the company's management
system that fosters performance improvement by
invoking behavioral change. The Fosfertil management
system is discussed further in Section 3.9
“ Environmental Management”.
Dam wall, clay fines tailings - Fosfertil, Brazil
Magnetite tailings dam - Fosfertil, Brazil
in responding to such failures (5). Examples of monitoring
and containment systems are presented in
Section 3.3 “Extraction” on ‘Solution Mining Pump
and Pipeline Monitoring and Control System’ and 3.4
“Handling” on ‘Watershed Protection’.
Other Potential Impacts
Wildlife may be adversely affected by exposure to contaminants
in waste. This is especially the case with
(5) Further information is available from other UNEP publications
on talings management and emergency preparedness
and response. These are listed in Appendix A.
aquatic species that are sensitive to elevated contaminant
levels. In some situations, water birds may be
susceptible to entrapment on brine ponds due to salting
of their feathers. A variety of techniques have been
used to discourage them landing on brine ponds,
including horns, gas, noise cannons and airboats.
Windblown dust or the erosion of fines from waste
disposal stacks and dams can be controlled to some
extent by stabilization techniques similar to that discussed
in Section 3.3 “Extraction”. These include:
covering with topsoil followed by revegetation,
mulching with organic material, spraying bonding
agents on the surface, or maintaining elevated water
levels in dams.