Presentation on theme: "Arsenic and Nitrogen handling in Mining Areas and Processes"— Presentation transcript:
1 Arsenic and Nitrogen handling in Mining Areas and Processes Green Mining SeminarEUROMINING 2013, TampereRaisa Neitola, GTK Mintec
2 Content GREEN MINING PROJECTS: ARSENAL – Arsenic Control in Mining Processes and Extractive IndustryMINIMAN – Solutions for Control of Nitrogen Discharges at Mines and QuarriesRaisa Neitola, GTK Mintec
3 WHY WE NEED GREEN MINING PROJECTS? The increased extraction of mineral resources and mining activities will place added pressure on the environmental issues and a proper water management in mining areasThe presence of arsenic and nitrogen compounds in mining areas and beneficiation processes creates the need to develop eco-efficient solutions to control different types of discharges in mining areasARSENAL and MINIMAN concentrate on developing technologies for management of arsenic and nitrogen discharges at the whole chain operations from quarrying and mining to end product and waste management.Raisa Neitola, GTK Mintec
5 WP1 Management of Arsenic in Beneficiation Process by Mineral Processing Methods OBJECTIVESTo get preliminary understanding of the mineralogical and environmental characteristic of arsenic-containing tailings and their behiaviour in pondsTo develop beneficiation process to produce high quality gold concentrate with very low arsenic grade and environmentally friendly tailingsEXPERIMENTAL WORKMineralogical and chemical characterization of arsenic containing ores, concentrates and tailings by MLA and XRFEnvironmental characteristic of As-containing tailingsBatch leaching tests, pH-dependency and static testsLaboratory scale flotation tests for arsenic containing gold oresOUTCOMESFlotation flowsheet to producerougher high quality gold concentratescavencer As-containing marginal concentrate, which is later treated by bio- and cyanide leaching methodsSulphide free and low arsenic containing tailings for disposalInsight for tailings characteristics at disposalRaisa Neitola, GTK Mintec
6 WP2 Sorption-based As-removal Technologies OBJECTIVESTo develop techniques for removal of trace level As-concentrations as a polishing step before discharge to the environmentTo find and apply cost-effective sorption materials for As-removal from mine watersEXPERIMENTAL WORKBatch tests with selected industrial by-products to assessment of sorption capacity and kinetics (commercial sorption material as reference)Column experiments with real mine water to simulate the end-use applicationOUTCOMESResults suggest sorption to be a viable option for trace level As-removal from mine watersPromising As-removal capacities found for pre-treated cast iron chipsChallenges remain in technical performance of the material (e.g clogging)Raisa Neitola, GTK Mintec
7 WP3 Management of As-containing Side Streams and Waste Materials by Bioprocessing OBJECTIVESTo develop biobased methods to process eco-efficiently industrial side streamTo reduce the amount of released arsenic and minimize environmental impacts of arsenic containing streams and waste materialsTo stabilize arsenic from waste waters binding it into the iron precipitateEXPERIMENTAL WORKMineralogical and chemical characterization of concentrates and bioleaching residues by MLA and XRFBioleaching of nickel concentrate, which is flotation by-products of talc productionLaboratory batch tests and continuous leaching tanksFluidized-bed reactor for waste watersOUTCOMESKnowledge and data for supporting the desing ofnew industrial plant for utilization of arsenic bearing side streamTreatment of arsenic-containing wastewaters through sorptionon biogenic iron precipitates was proved to be efficientStability of arsenic in the iron precipitate was pH-dependentRaisa Neitola, GTK Mintec
8 WP4 Environmental research SiilinjärviOBJECTIVESTo study and compare natural and anthropogenic As at two geologically different mine sites (Kittilä Suurikuusikko gold mine, Yara Siilinjärvi industrial area)To assess and compare ecological risks at study sitesTo model the behaviour of natural and anthropogenic AsEXPERIMENTAL WORKDesk study of As geochemistry in mine environmentsWater, soil and bedrock sampling & geochemical analysisModelling study (PHREEQC)Assessment of ecological risksOUTCOMESDespite of the geology of mine site, mining activity has increased the proportion of available and potentially mobile As in soilMining activities have increased the ecological risks bychanging As into more soluble and mobile formelevating As concentrations in the surrounding environmentAs mobility in soil depends on adsorption by iron oxyhydroxidesDesorption of arsenic is potential risk to environment (e.g. wetlands)KittiläRaisa Neitola, GTK Mintec
9 MINIMAN – Solutions for Control of Nitrogen Discharges at Mines and Quarries Explosion fumes to airGases: N2, NOxSpillage to surface and groundwaterIons : NO3-, NH4+Mined ore and waste rockRemnants of explosives to the extraction facility → tailingsRemnants of explosives to the waste rock area → potential leachingFinal productTimetable: Budget: 920 k€NEEDSBetter understanding of the behaviour of nitrogen compoundsMinimizing of nitrogen transportRemoval of N-compounds from mine watersAPPROACHAnalysis of sources, behaviour and management opportunities of nitrogen compoundsBiological reactor process and electrochemical /adsorption process for nitrogen removalBENEFITSKnowledge, tools and technological solutions for nitrogen control at minesUSERS & COMPETITIONTechnology companies, mines, consults, authorities, other stakeholders(Outotec Oyj, Kemira Oyj, Ekokem-Palvelu Oy, Outokumpu Chrome Oy, Agnico Eagle Finland Oy, Yara Suomi Oy, FQM Kevitsa Mining Oy, Nordic Mines AB, Nordkalk Oy Ab, Infra ry, Kiviteollisuusliitto ry,BK-automation Ky)Non-nitrogen explosives/explosion techniques (not in near future)Major nitrogen sources at mine sitesAmmonium nitrate based explosivesCyanide used in gold extractionChallengesBehaviour and release of nitrogen compounds from waste rock and tailingsWater: Relatively low (NO3-, NH4+) concentrations, high volumes, high ionic concentrations, Nordic conditions
10 WP1 Removal of Nitrogen compounds by Biological techniques OBJECTIVESTo evaluate the feasibility of biological methods to remove nitrate and ammonium from metal-rich mine wastewaters at low-pHEXPERIMENTAL WORKPCR/DGGE analysis for monitoring the evolution of microbial communityBatch tests for the assessment of metal toxicity and pH effect on microbial activityFluidized-bed and membrane bioreactors for denitrification and nitrication experimentsOUTCOMES SO FARDenitrification of acidic water is feasible whereas nitrification is more pH sensitiveBoth nitrification and denitrification tolerate metal concentrations that are typical in AMD
11 WP2 Nitrogen sorption experiments OBJECTIVESTo find and apply cost-effective sorption materials for nitrogen compounds from mine watersTo compare different sorption materials and their ability to remove low concentrations of ammonia and nitrate from mine watersEXPERIMENTAL WORKDesk study of the potential sorption methods and materials based on existing knowledgeBatch and column tests using natural minerals based materials (e.g. zeolite, vermiculite) and other sorbent materials (e.g. carbon) with real/synthetic waterRegeneration tests of sorbent materialsOUTCOMES SO FARZeolite sorption is potentially a functioning method of ammonia removal from mine waste waterCase dependant feasibility study and pilot scale testing are needed to confirm economics and feasibilityNatural zeolites arehydrated aluminiosilicates with a three-dimensional structure and highadsorption capacity.
12 WP3 Electrochemical nitrogen capture OBJECTIVESTo develop novel electrochemical technique for nitrate and ammonia capture suitable also for Nordic conditionsEXPERIMENTAL WORKLaboratory scale research using a continuous flow cassette reactorSynthetic wastewater used in a self constructed reactorCooperation with University of Queensland Advanced Water Management CentreOUTCOMES SO FARElectrochemically enhanced stripping is potentially a feasible technology for variety of inorganic streams for nitrogen capture in the future – including mine wastewatersMore research is needed for material selection and development and process optimization and reactor configurationHigh ion concentration of mine waste water can cause fouling problems
13 WP4 Aging tests OUTCOMES SO FAR OBJECTIVES To evaluate the nitrogen discharge from the mine sites‘Nitrogen smudging’ (contamination by explosive originated nitrogen compounds) of otherwise mineralogically and chemically inert waste rocks of good technical quality hinders the utilization of these product streamsTo gather essential data on the behaviour of nitrogenous compounds present in the environments of mines and quarriesEXPERIMENTAL WORKMonitoring the surface waters around the quarriesAging tests at the quarries1000 m3 IBC-container + waste rockOUTCOMES SO FARData forms a basis for a holistic view on need andoptions for nitrogen management in mining and quarrying that takes into account the scale of the operationsMining activity seems to have relatively low nitrogen emissions, ”nitrogen smudging” should not prevent the utilization of waste rock materialThe ”first flush” of nitrogen from waste rocks comes fast and is relatively short(collected immediately after the excavation of a diabase block)
14 CONCLUSIONSThe results of ARSENAL project suggest that by novel mineral processing methods and proper water treatment methods the amount of As-compounds in tailings and effluents can be reduced to levels that satisfy the regulations concerning mining waste management.So far, MINIMAN project generated new know-how on the behaviour of N compounds in mining areas and better understanding of the nitrogen discharge issue as well as developed advanced technologies for the removal of nitrogen compounds from mine waters.Raisa Neitola, GTK Mintec
15 Thank You for Your Attention! Raisa Neitola, GTK Mintec
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