Arsenic and Nitrogen handling in Mining Areas and Processes Green Mining Seminar 12.9.2013...

Arsenic and Nitrogen handling in Mining Areas and Processes

Green Mining Seminar 12.9.2013

EUROMINING 2013, Tampere

12.9.2013 1Raisa Neitola, GTK Mintec

Content

GREEN MINING PROJECTS:

1. ARSENAL – Arsenic Control in Mining Processes and Extractive Industry

2. MINIMAN – Solutions for Control of Nitrogen Discharges at Mines and Quarries


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 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.


ARSENAL – Arsenic Control in Mining Processes and Extractive Industry

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 necessityAPPROACH• 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 toolsBENEFITS• 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

Timetable: 1.1.2011 -31.8.2013 Budget: 1 400 k€

©Loukola-Ruskeeniemi, Arseeni Suomen luonnossa ympäristövaikutukset ja riskit, 2004

12.9.2013

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


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)


0,022,3

7,9

14

46

0

10

20

30

40

50

Waste rock Granulatedsteel slag

Ash pellet Granulatedferric oxo-hydroxide(CFH 12)

Cast iron chipsMax

imu

m A

s-rem

ova

l cap

acit

y, m

g/g

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


WP4 Environmental research• 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)


Siilinjärvi

Kittilä

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 minesUSERS & 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

MINIMAN – Solutions for Control of Nitrogen Discharges at Mines and QuarriesTimetable: 1.1.2012 -31.12.2013 Budget: 920 k€

Explosion

fumes to air

• Gases: N2, NOxSpillage

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 produ

ct

12.9.2013

WP1 Removal of Nitrogen compounds by Biological techniques

12.9.2013

• 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

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

12.9.2013

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

12.9.2013

WP4 Aging tests

• 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 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

12.9.2013

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.



Thank You for Your Attention!

Arsenic and Nitrogen handling in Mining Areas and Processes Green Mining Seminar 12.9.2013...

Documents

Transcript of Arsenic and Nitrogen handling in Mining Areas and Processes Green Mining Seminar 12.9.2013...