Environmental Aspects of Phosphate and Potash Mining

MinedevelopmentEnvironmental Aspects of Phosphate and Potash MiningWater quality can be affected by the release of slurrybrines and contaminants into process water. Surfacewaters may be contaminated by: The erosion of fines from disturbed ground suchas open-cut workings, overburden dumps andspoil piles and waste disposal facilities;The release or leakage of brines;The weathering of overburden contaminants,which may then be leached.Large volumes of water are typically required by miningand beneficiation activities. This waterconsumption may lead to a fall in the level of the watertable, affecting the surrounding ecosystem and potentiallyresulting in competition with other users.The land surface and sub-surface is disturbed by activitiessuch as: The extraction of ore; The deposition of overburden; The disposal of beneficiation wastes; The subsidence of the surface.These activities could result in wide range of potentialimpacts on the land, geological structure, topsoil,aquifers and surface drainage systems. Additionally,the removal of vegetation may affect the hydrologicalcycle, wildlife habitat and biodiversity of the area. Insome instances, sites of archaeological, cultural orother significance may be affected.Social goods and intangible values such as communitylifestyles, land values and the quality of theecosystem in the vicinity of the mine site could beaffected by factors such as: Modification of the landscape; Noise and vibration from activities such as blastingand the operation of equipment; Changes in wildlife habitat.The major potentially adverse environmental effectscould occur during the different activities of the mininglife cycle in Figure 3.1.1. Generally the activities ofmost significance are construction, extraction, beneficiationand waste disposal. Associated activities mayhave an impact but these tend to be relatively lessimportant. Rehabilitation and closure can have someimpact, but these activities are carried out with theobjective of repairing any adverse effects that mayhave occurred during mining, to leave a safe and stablesite. Rehabilitation is more effective whenconducted progressively throughout the life of theoperation. Adopting a holistic approach to planningand environmental management, that encompassesthe entire life cycle, helps to prevent or mitigate environmenteffects from the outset, while fosteringstewardship of the ore resource and the land underwhich it lies.The present chapter has been organized according tothe major activities associated with the mining lifecycle.Within each activity, the major environmentalissues are raised, followed by a general discussion ofthe environmental practices employed by industry.The discussion is illustrated by examples of good andinnovative environmental practices identified duringthe project site visits. These demonstrate specificindustry responses.3.2 Mine Development: Exploration,Planning, Approval and ConstructionMine development consists of a sequence of activities: Prospecting and exploration work to locate anddelineate the ore resource; Economic, environmental and technical feasibilityassessment of the orebody; Planning and design of the mine layout, site infrastructureand the mining sequence; Obtaining relevant government permits andapprovals; Construction and commissioning of the operation.Most environmental impacts during this stage of themining life cycle are typically associated with explorationand construction. Effective planning,commencing at this stage and continuing throughoutthe life of the mine, has a great influence on minimizingthe impact of the operation.Figure 3.2.1Potential environmental effects : mine developmentExploration,assessment,planning andconstructionLand surface disturbanceAir emissionsWater contaminationNoise and vibrationPlanning is important to avoid or reduce adverse environmentalimpacts over the life of the mine and afterclosure. Planning is most effective when the entire lifeof mine is encompassed. Defining the final objectivesof mine closure from the outset allows an optimumbalance between operational, rehabilitation and closuregoals to be selected, thus minimizing the cost ofthese activities.