Environmental Aspects of Phosphate and Potash Mining

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The Environmental Approach of the Phosphate Rock and Potash Mining IndustrySolid Waste Disposal and Water Management System with Performance Feedback34The Tapira mining and beneficiation complex is locatedin the state of Minas Gerais, Brazil and owned and operatedby Fertilizantes Fosfatados S.A. (Fosfertil).Phosphate rock is extracted from an igneous depositusing an open-cut truck and shovel mining method.Annual production is around 11 million tonnes of oreper year. The phosphate ore is concentrated in the beneficiationplant before transport through a slurrypipeline to the Uberaba fertilizer processing complex.The waste disposal and water management systemconsists of five dams in total, three of which are used forwaste storage and the other two are used to clarify andtreat water before release.The beneficiation wastes (clay fines, sand and magnetitetailings) are disposed of into two valley-styletailings dams, while a small dam is located adjacent tothe plant to capture any spills. Clay fines are transportedfrom the beneficiation plant to one of the tailingsdam through an 8-kilometre-long open canal flowingunder gravity, while the sand and magnetite are disposedof to the other tailings dam.Effluent releases from the magnetite and sand tailingsdam and the plant spillage dam are passed to a clarificationdam.The fresh water dam receives the water releases fromthe clarification dam and the clay fines tailing dam aswell as the natural inflow of the Ribeiro Inferno a localstream. This dam completes the treatment/clarificationprocess before excess water is released to the RioAraguari, a major regional river.The water quality meetsBrazilian water quality standards while the release rateis adjusted to correspond to the normal inflow of theRibeiro Inferno into the dam.The company has chosen to locate the fresh waterintake for the beneficiation plant at the release point ofthe fresh water dam. Performance of the beneficiationplant is sensitive to water quality with any deteriorationimposing a cost on the company in terms of reducedproduct recovery.The water management system lends itself to improvedperformance through the built-in positive feedbackloop. This is consistent with the company's managementsystem that fosters performance improvement byinvoking behavioral change. The Fosfertil managementsystem is discussed further in Section 3.9“ Environmental Management”.Dam wall, clay fines tailings - Fosfertil, BrazilMagnetite tailings dam - Fosfertil, Brazilin responding to such failures (5). Examples of monitoringand containment systems are presented inSection 3.3 “Extraction” on ‘Solution Mining Pumpand Pipeline Monitoring and Control System’ and 3.4“Handling” on ‘Watershed Protection’.Other Potential ImpactsWildlife may be adversely affected by exposure to contaminantsin waste. This is especially the case with(5) Further information is available from other UNEP publicationson talings management and emergency preparednessand response. These are listed in Appendix A.aquatic species that are sensitive to elevated contaminantlevels. In some situations, water birds may besusceptible to entrapment on brine ponds due to saltingof their feathers. A variety of techniques have beenused to discourage them landing on brine ponds,including horns, gas, noise cannons and airboats.Windblown dust or the erosion of fines from wastedisposal stacks and dams can be controlled to someextent by stabilization techniques similar to that discussedin Section 3.3 “Extraction”. These include:covering with topsoil followed by revegetation,mulching with organic material, spraying bondingagents on the surface, or maintaining elevated waterlevels in dams.
Environmental Aspects of Phosphate and Potash MiningTailings Dam Audit ProgramThe Catalão phosphate rock mining and beneficiationcomplex in the state of Goiás, Brazil is owned and operatedby Copebras S.A., part of the Anglo AmericanCorporation of South Africa group.The operation deposits phosphate and magnetite tailingsstreams in a conventional valley style tailings dam.The dam wall has been constructed from compactedclay and coarse phosphate tailings.The dam is inspected about once a year, as part of anongoing monitoring and audit program.The inspectionencompasses the general condition of the dam andassociated infrastructure, including the dam wall,decant facilities, slurry delivery and deposition andmonitoring piezometers. Information is documented ina comprehensive report with numerous photographsto illustrate the current state of the facility.The annual inspection and review complements thedaily monitoring and supervision of the facility by providinga check on performance and identifying andproposing remedial actions for longer term issues. Thisis supported by numerical evaluations using monitoringdata to confirm the continued structural integrityof the dam wall.Water release quality is evaluated twice a year (dry andwet seasons) as part of the regular surface and groundwater monitoring program for the entire complex. Thisprogram includes an analysis of the pond water, seepagefrom the tailings dam and any effects onsurrounding groundwater.The annual monitoring and audit program facilitatesinformed management of the tailings disposal facilityand reduces the risk of failure.Tailings dam, wall in distance - Copebras S.A., BrazilTailings dam seepage water release - Copebras S.A., BrazilWind-blown Tailings Dust ControlIn South Africa, Foskor Ltd. has controlled windblowndust by ploughing furrows in the surface of dry tailings,perpendicular to the prevailing wind direction. The furrowscreate eddies that trap dust particles mobilized bythe wind reducing air pollution.Furrows in dry tailings - Foskor Ltd, South Africa
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Page 4 and 5: AcknowledgementsA number of people
Page 6 and 7: PrefaceThis report on the environme
Page 8 and 9: Introduction2During recent decades,
Page 10 and 11: Introduction4Figure1.2The mineral f
Page 12 and 13: Overview of Phosphate Rock and Pota
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Page 28 and 29: HandlingThe Environmental Approach
Page 30 and 31: BeneficiationThe Environmental Appr
Page 42 and 43: ClosureThe Environmental Approach o
Page 44 and 45: RehabilitationThe Environmental App
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Page 62 and 63: AppendicesAppendix D. Glossary of F
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