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Arsenic and Nitrogen handling in Mining Areas and Processes

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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 Seminar EUROMINING 2013, Tampere Raisa Neitola, GTK Mintec

ARSENAL – Arsenic Control in Mining Processes and Extractive Industry MINIMAN – Solutions for Control of Nitrogen Discharges at Mines and Quarries Raisa Neitola, GTK Mintec

The increased extraction of mineral resources and mining activities will place added pressure on the environmental issues and a proper water management in mining areas The 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 areas ARSENAL 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

4 ARSENAL – Arsenic Control in Mining Processes and Extractive Industry
Timetable: Budget: k€ NEEDS Arsenic is a world-wide challenge Arsenic is commonly associated with ores containing metals such as gold It is easily solubilized in water phase Control of arsenic in all mining operations is a necessity APPROACH New mineral processing and water treatment solutions for arsenic removal Novel bio-based treatment processes for arsenic containing wastes and streams Monitoring and environmental risk assessment tools BENEFITS Better knowledge and new management tools on arsenic in the mining area Eco-efficient solutions for mining industry to control and remove arsenic Minimization of health and environmental risks related to arsenic USERS & COMPETITION Technology companies, mines, consults, authorities, other stakeholders (Outotec Oyj, Kemira Oyj, Ekokem-Palvelu Oy, Agnico Eagle Oy, Endomines Oy, Nordic Mines AB, Pyhäsalmi Mine Oy, YARA Suomi Oy, Mondo Minerals B.V. Branch Finland) Arsenic behavior is highly depend on prevailing conditions and processes Special, tailor-made and global approaches are a challenge and a possibility ©Loukola-Ruskeeniemi, Arseeni Suomen luonnossa ympäristövaikutukset ja riskit, 2004

5 WP1 Management of Arsenic in Beneficiation Process by Mineral Processing Methods
OBJECTIVES To get preliminary understanding of the mineralogical and environmental characteristic of arsenic-containing tailings and their behiaviour in ponds To develop beneficiation process to produce high quality gold concentrate with very low arsenic grade and environmentally friendly tailings EXPERIMENTAL WORK Mineralogical and chemical characterization of arsenic containing ores, concentrates and tailings by MLA and XRF Environmental characteristic of As-containing tailings Batch leaching tests, pH-dependency and static tests Laboratory scale flotation tests for arsenic containing gold ores OUTCOMES Flotation flowsheet to produce rougher high quality gold concentrate scavencer As-containing marginal concentrate, which is later treated by bio- and cyanide leaching methods Sulphide free and low arsenic containing tailings for disposal Insight for tailings characteristics at disposal Raisa Neitola, GTK Mintec

6 WP2 Sorption-based As-removal Technologies
OBJECTIVES To develop techniques for removal of trace level As-concentrations as a polishing step before discharge to the environment To find and apply cost-effective sorption materials for As-removal from mine waters EXPERIMENTAL WORK Batch 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 application OUTCOMES Results suggest sorption to be a viable option for trace level As-removal from mine waters Promising As-removal capacities found for pre-treated cast iron chips Challenges 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
OBJECTIVES To develop biobased methods to process eco-efficiently industrial side stream To reduce the amount of released arsenic and minimize environmental impacts of arsenic containing streams and waste materials To stabilize arsenic from waste waters binding it into the iron precipitate EXPERIMENTAL WORK Mineralogical and chemical characterization of concentrates and bioleaching residues by MLA and XRF Bioleaching of nickel concentrate, which is flotation by-products of talc production Laboratory batch tests and continuous leaching tanks Fluidized-bed reactor for waste waters OUTCOMES Knowledge and data for supporting the desing of new industrial plant for utilization of arsenic bearing side stream Treatment of arsenic-containing wastewaters through sorption on biogenic iron precipitates was proved to be efficient Stability of arsenic in the iron precipitate was pH-dependent Raisa Neitola, GTK Mintec

8 WP4 Environmental research
Siilinjärvi OBJECTIVES To 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 sites To model the behaviour of natural and anthropogenic As EXPERIMENTAL WORK Desk study of As geochemistry in mine environments Water, soil and bedrock sampling & geochemical analysis Modelling study (PHREEQC) Assessment of ecological risks OUTCOMES Despite of the geology of mine site, mining activity has increased the proportion of available and potentially mobile As in soil Mining activities have increased the ecological risks by changing As into more soluble and mobile form elevating As concentrations in the surrounding environment As mobility in soil depends on adsorption by iron oxyhydroxides Desorption of arsenic is potential risk to environment (e.g. wetlands) Kittilä Raisa Neitola, GTK Mintec

9 MINIMAN – Solutions for Control of Nitrogen Discharges at Mines and Quarries
Explosion fumes to air Gases: N2, NOx Spillage to surface and groundwater Ions : NO3-, NH4+ Mined ore and waste rock Remnants of explosives to the extraction facility → tailings Remnants of explosives to the waste rock area → potential leaching Final product Timetable: Budget: 920 k€ NEEDS Better understanding of the behaviour of nitrogen compounds Minimizing of nitrogen transport Removal of N-compounds from mine waters APPROACH Analysis of sources, behaviour and management opportunities of nitrogen compounds Biological reactor process and electrochemical /adsorption process for nitrogen removal BENEFITS Knowledge, tools and technological solutions for nitrogen control at mines USERS & COMPETITION Technology 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 sites Ammonium nitrate based explosives Cyanide used in gold extraction Challenges Behaviour and release of nitrogen compounds from waste rock and tailings Water: Relatively low (NO3-, NH4+) concentrations, high volumes, high ionic concentrations, Nordic conditions

10 WP1 Removal of Nitrogen compounds by Biological techniques
OBJECTIVES To evaluate the feasibility of biological methods to remove nitrate and ammonium from metal-rich mine wastewaters at low-pH EXPERIMENTAL WORK PCR/DGGE analysis for monitoring the evolution of microbial community Batch tests for the assessment of metal toxicity and pH effect on microbial activity Fluidized-bed and membrane bioreactors for denitrification and nitrication experiments OUTCOMES SO FAR Denitrification of acidic water is feasible whereas nitrification is more pH sensitive Both nitrification and denitrification tolerate metal concentrations that are typical  in AMD

11 WP2 Nitrogen sorption experiments
OBJECTIVES To find and apply cost-effective sorption materials for nitrogen compounds from mine waters To compare different sorption materials and their ability to remove low concentrations of ammonia and nitrate from mine waters EXPERIMENTAL WORK Desk study of the potential sorption methods and materials based on existing knowledge Batch and column tests using natural minerals based materials (e.g. zeolite, vermiculite) and other sorbent materials (e.g. carbon) with real/synthetic water Regeneration tests of sorbent materials OUTCOMES SO FAR Zeolite sorption is potentially a functioning method of ammonia removal from mine waste water Case dependant feasibility study and pilot scale testing are needed to confirm economics and feasibility Natural zeolites are hydrated aluminiosilicates with a three-dimensional structure and high adsorption capacity.

12 WP3 Electrochemical nitrogen capture
OBJECTIVES To develop novel electrochemical technique for nitrate and ammonia capture suitable also for Nordic conditions EXPERIMENTAL WORK Laboratory scale research using a continuous flow cassette reactor Synthetic wastewater used in a self constructed reactor Cooperation with University of Queensland Advanced Water Management Centre OUTCOMES SO FAR Electrochemically enhanced stripping is potentially a feasible technology for variety of inorganic streams for nitrogen capture in the future – including mine wastewaters More research is needed for material selection and development and process optimization and reactor configuration High ion concentration of mine waste water can cause fouling problems

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 streams To gather essential data on the behaviour of nitrogenous compounds present in the environments of mines and quarries EXPERIMENTAL WORK Monitoring the surface waters around the quarries Aging tests at the quarries 1000 m3 IBC-container + waste rock OUTCOMES SO FAR Data forms a basis for a holistic view on need and options for nitrogen management in mining and quarrying that takes into account the scale of the operations Mining activity seems to have relatively low nitrogen emissions, ”nitrogen smudging” should not prevent the utilization of waste rock material The ”first flush” of nitrogen from waste rocks comes fast and is relatively short (collected immediately after the excavation of a diabase block)

14 CONCLUSIONS The 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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