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International Atomic Energy Agency
IX.4.9.IX.4.9.Mining WasteMining Waste
Disposal options for different waste types, safety principles and technologies for assuring long-term
safety, safety assessment methods
International Atomic Energy Agency04/19/23NSRW/WSS 2
Waste streams generated during the different phases of Waste streams generated during the different phases of mining projectsmining projects
• Exploration wastes
• Mining wastes
• Milling wastes
• In situ leach (ISL) wastes
• Miscellaneous wastes
• Decommissioning wastes
International Atomic Energy Agency04/19/23NSRW/WSS 3
Tailings properties: Tailings properties: Radiological componentsRadiological components
• The major portion of the radionuclides present in the ore remains in the tailings after uranium has been extracted
• Significant radionuclides are the decay series for uranium and thorium
• 226 Radium is often considered as the most important radiotoxic decay product in the decay series
• 226 Radium produces 222 radon-a radioactive inert gas, whose decay products can cause lung cancer
International Atomic Energy Agency04/19/23NSRW/WSS 4
Radioactive decay series for uranium and thoriumRadioactive decay series for uranium and thorium
International Atomic Energy Agency04/19/23NSRW/WSS 5
Waste streams- Waste streams- Exploration WastesExploration Wastes
• Material excavated from trenches etc
• Drilling sludge, cuttings and dust
• Core samples
• Disturbed ground, overburden materials
• Drilling fluids, mechanical scrap, grout and cement residues, general refuse
Drill rig P.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 6
Waste Streams: Waste Streams: Mining WastesMining Wastes• Solid wastes
• Waste rock and low grade ore from open pits and underground mines (including sub-economic material)
• Industrial waste
• Liquid wastes• Contaminated mine dewatering
water
• Contaminated surface water (process residues, oily wastes etc)
• Airborne emissions• Radon emissions from waste rock
and ore piles, open-pits and underground mines
• Dust emissions from mining and hauling activities
Tailings dam and waste stockpilesP.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 7
Waste Streams: Waste Streams: Milling wastesMilling wastes• Solid wastes
• Tailings
• Sludge, filter cakes and scales
• Process residues e.g. sulphur, scats
• Liquid wastes• Barren and Decant solutions
• Seepage from tailings management areas
• Leachate and runoff from waste rock, low grade ore and ore piles
• Plant washings
• Airborne emissions• Dust from screening and crushing
operations
• Toxic fumes from the mill, acid plant, calciner etc
• Yellow cake particles No.1 pit & tailings repository, Ranger Uranium Mine, Australia P.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 8
Waste Streams: In situ leaching (ISL) wastes
• Extraction plant liquid waste solutions (bleed solution, wasted barren solution, filter backwash)
• Small amount of solids in the form of sludge and salts
• Ion exchange residues
• Used filter media
• Chemical residues
• Industrial waste
Beverley ISL wellfield,
Heathgate Resources Pty Ltd
International Atomic Energy Agency04/19/23NSRW/WSS 9
Waste streams: Waste streams: Miscellaneous wastesMiscellaneous wastes
• Domestic solid and liquid wastes
• Contaminated scrap material and equipment
• Hazardous substances (oils, chemicals and others)
• Laboratory wastes (solid, gaseous and liquid)
International Atomic Energy Agency04/19/23NSRW/WSS 10
Waste streams: Waste streams: Decommissioning wastesDecommissioning wastes
• Decommissioning procedures generate wastes
• Scale from pipes and process vessels
• Residual liquids from mill components
• Decontamination residues, both solid and liquid
• Building materials, possibly contaminated
• Contaminated scrap metal from plant and machinery
• Process residues
• Unprocessed ore and low grade rock materials
Nabarlek Mill, Australia
P.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 11
Radiological and non-radiological properties of wastesRadiological and non-radiological properties of wastes
• Properties of tailings• The major component of wastes in terms of volume and probably
radioactivity
• Need to be managed for a long time
• Other liquid and solid wastes• May be no less important than tailings as contaminant source
• May have potential to move into wider environment relatively easily
International Atomic Energy Agency04/19/23NSRW/WSS 12
Properties of TailingsProperties of Tailings
• Main properties to be considered when considering tailings management options include:
• Uranium ore grade
• Radiological components
• Acid generation potential
• Non-radiological contaminants
• Waste concentrates
Sub aerial tailings deposition in mined out pit
P.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 13
Properties of Tailings: Uranium Ore GradeProperties of Tailings: Uranium Ore Grade
• Uranium content of ore ranges from less than 0.1% to over 40%
• High grade ore is usually diluted with low grade or waste rock prior to milling to produce a constant U content for efficient process input and control
• Feed grades to the mill usually range from 0.1% to several per cent
• Tailings produced from high grade ore contain proportionally higher concentration of radionuclides per unit of product
• Low grade ore produces proportionally more tailings per unit of product
International Atomic Energy Agency04/19/23NSRW/WSS 14
Tailings properties: Ore Grade versus tailings volumeTailings properties: Ore Grade versus tailings volume
Mine
Ore Grade
(%)
Uranium Production
(t)
Volume of Tailings
(t)
Uranium / Tailings
Ratio
Beaverlodge 0.21 21,236 10,100,000 475
Key Lake 1.95 71,611 4,400,000 61
McArthur River
12.75 160,200 4,400,000 27
International Atomic Energy Agency04/19/23NSRW/WSS 15
Tailings properties: Tailings properties: Acid Mine DrainageAcid Mine Drainage• Caused by the oxidation and
hydrolysis of sulfide materialssuch as pyrite and pyrrhotite in the presence of moisture and oxygen
• Common problem around the world in many mines in both tailings and waste rock
• Oxidation process forms sulfuric acid, which results in:
• Elevated concentrations of toxic heavy metals and radionuclides in discharges and seepage from the tailings
• Reduction in pH of adjacent water systems
• Unacceptable environmental impacts
Acid drainage seeping from waste rock stockpile
Rum Jungle Uranium Mine, Australia. P.Waggitt
International Atomic Energy Agency04/19/23NSRW/WSS 16
Tailings properties: Tailings properties: Non-radiological ContaminantsNon-radiological Contaminants
• Large number of non-radiological contaminants, mostly metals
• Contaminants in tailings depend on the ore and milling process used
• Non-radiological contaminants most commonly found in the tailings
• are listed in the next slide
• May be potential sources of contamination
• Useful as tracers in monitoring
International Atomic Energy Agency04/19/23NSRW/WSS 17
Tailings properties: Tailings properties: Non-radiological Contaminants Non-radiological Contaminants (continued)(continued)
• Metallic componentsArsenic Barium Boron Cadmium Calcium Chromium
Copper Iron Lead Magnesium Manganese Mercury
Nickel Selenium Silver Vanadium Zinc
Molybdenum
• Non-MetalsAmmonium Carbonates Chlorides Cyanide
Isodecanol
Kersosene Nitrates Phosphoric acid Pyrite Pyrrhotite
Sulphates Tertiary amines Tributyl phosphate
International Atomic Energy Agency04/19/23NSRW/WSS 18
Tailings properties: Tailings properties: Waste Precipitates and ConcentratesWaste Precipitates and Concentrates
• Solid wastes formed as the result of mill effluents and other contaminated waters treatment
• Examples:
• Sludge from the neutralization of acidic solutions
• Sludge from the treatment process of mill effluent with barium chloride
• Brine streams from water treatment e.g. reverse osmosis or ion exchange
• Usually stored within the tailings management areas
• May cause problems due to their poor consolidation properties and contaminant content
International Atomic Energy Agency04/19/23NSRW/WSS 19
Contaminant Release from Uranium Mill tailingsContaminant Release from Uranium Mill tailings
• Most important release mechanisms
• Air emissions: radon and dust
• Seepage from tailings management areas
• Structural failure of containment structures
• Spills during the transport of tailings
• Erosion of covers
• Unauthorized disturbance or removal of tailings
Unauthorized digging in tailingsD.Reisenweaver
International Atomic Energy Agency04/19/23NSRW/WSS 20
General Exposure Pathways to HumansGeneral Exposure Pathways to Humans• Atmospheric pathways
• Inhalation of radon and its daughters
• Inhalation of radioactive particulates
• External irradiation (gamma)
• Atmospheric and terrestrial pathways
• Ingestion of contaminated foodstuffs
• External irradiation
• Aquatic pathways• Ingestion of contaminated water
• Ingestion of foods produced using irrigation, fish and other aquatic biota
• External irradiation
Sheep grazing on tailings areaD.Reisenweaver
International Atomic Energy Agency04/19/23NSRW/WSS 21
Environmental transfer and Dose Model (chart) Environmental transfer and Dose Model (chart)
International Atomic Energy Agency04/19/23NSRW/WSS 22
Non-Radiological ContaminantsNon-Radiological Contaminants
• Often the impacts of non-radiological contaminants is as important or even more important than radiological impacts (however radiological impacts may be more important to the public)
• Non- radiological parameters may also be necessary to understand the environmental processes driving the dispersion of radioactive contaminations (e.g. ph, ground water head, etc.)
• Non-radioactive parameters may also be used as:
• analogues for radioactive contaminants (e.g. natural lead for lead-210 where there is a direct relationship)
• tracers for contamination studies and models
International Atomic Energy Agency04/19/23NSRW/WSS 23
Long Term ImpactLong Term Impact
• The radiation in uranium waste rock and tailings is extremely long lived
• Impacts cannot only be considered in the short term but must include the potential effects on future generations
• Often larger impacts occur after the closure of a facility
Wall made using tailings in the mortarD.Reisenweaver
International Atomic Energy Agency04/19/23NSRW/WSS 24
Institutional ControlInstitutional Control
• Radiation Protection and Safety can only be assured if there is a system in place and it is working and it is consistent
• The system has to be organized and implemented by an independent “power” to ensure it is effective
• Because the potential problems are so long lived, safety has to be organised by a body that will also be long lived
• Governments are probably the only organisations likely to be around long enough
• We call the process behind these systems Institutional Control
• Includes:
• Laws to provide a legal basis for control and penalties for breaches
• Funding to implement the process, provision of inspectors and safety guides, manuals etc
• Setting approved levels of training for operators and regulators alike
• Providing for continuous improvement in the system and interaction with other authorities, both national and local, as well as international
International Atomic Energy Agency04/19/23NSRW/WSS 25
SummarySummary
• Mining and milling generates a range of different wastes which have the potential to impact the public and the environment in a number of ways
• There is a range of pathways by which the operation may cause exposure and these may change over the life of the facility
• Tailings and sometimes waste rock generally have the most potential for providing significant impacts
• Non-radiological contaminants are important in their own right, but also may give information about the dispersal of the radioactive components
• Economic and social factors are an important consideration for both the operator and the regulator
• Long term impacts often are potentially more important than impacts arising during operations
• The creation of Institutional Control provides a mechanism for assurance of protection and safety in the long term