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Arsenic and nitrogen compound discharges<br />
in mining and solutions to their removal<br />
Green Mining Annual Seminar<br />
24.10.2012<br />
Helsinki<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 1
CONTENT<br />
• GTK MINTEC<br />
• 2 GREEN MINING PROJECTS:<br />
1. <strong>ARSENAL</strong> – Arsenic Control in<br />
Mining Processes and Extractive<br />
Industry<br />
2. MINIMAN – Solutions for<br />
Control of Nitrogen Discharges at<br />
Mines and Quarries<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 2
GTK MINERAL PROCESSING, OUTOKUMPU<br />
• One of the leading mineral processing research<br />
facilities in Europe<br />
• Entire research chain from mineralogical studies<br />
to process design<br />
• Focus of the R&D activities are:<br />
process development for new orebodies and<br />
troubleshooting/process development on the<br />
existing beneficiation plants as well as<br />
solutions for material recycling and soil<br />
remediation<br />
• Turnover 4,9 M€ (2011)<br />
– Over 60 % from confidential contract<br />
research for clients<br />
– Clients from abroad (50 %)<br />
• Total staff 43 people + Labtium Oy 6 people<br />
3
<strong>ARSENAL</strong> – Arsenic Control in Mining Processes<br />
and Extractive Industry<br />
• Timetable and budget: 1.1.2011-31.12.2012 and 1.4 M€<br />
• Research partners: GTK, VTT ja TTY<br />
• Industrial partners:<br />
Company Deposit Ore/concentrates<br />
Outotec Oyj<br />
Kemira Oyj<br />
technology and service providers<br />
Ekokem-Palvelu Oy<br />
Agnico Eagle Oy Suurikuusikko (Au) Arsenopyrite, pyrite<br />
Endomines Oy Pampalo (Au) Pyrite<br />
Nordic Mines AB Laivakangas (Au) Arsenopyrite, löllingite<br />
Pyhäsalmi Mine Oy Pyhäsalmi (Zn-Cu-S) Pyrite concentrate<br />
YARA Suomi Oy<br />
Mondo Minerals B.V.<br />
Branch Finland<br />
Siilinjärvi<br />
Sotkamo<br />
Gersdorffite and nickel<br />
concentrate<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 4
WHAT IS ARSENIC<br />
• Arsenic (As) is a metalloid, which occurs<br />
naturally in the bedrock<br />
• Arsenic and many of its compounds are<br />
toxic and environmentally hazardous<br />
• Arsenic can exist in four oxidation states:<br />
As(-III), As(0), As(III), and As(V).<br />
– As 3+ is more toxic than As 5+<br />
• Solubility of arsenic depending on pH and<br />
oxidation/reduction conditions<br />
©Zumdahl, Chemistry, 1993<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 5
ARSENIC IN MINING AREAS<br />
• Arsenic occurs naturally in rocks<br />
and soil as well as in water and air<br />
– Only 1-2 % of the Finnish<br />
bedrock contains over 10 mg/kg<br />
arsenic<br />
• Arsenic is commonly associated<br />
with ores containing metals such<br />
as gold, copper and lead<br />
• The most common arsenic<br />
minerals are arsenopyrite (FeAsS)<br />
and löllingite (FeAs 2 )<br />
• Other arsenic minerals are<br />
cobaltite (CoAsS), gersdorffite<br />
(NiAsS) and nickoline (NiAs)<br />
Sotkamo<br />
Pampalo<br />
Raisa Neitola, GTK Mintec<br />
The impacts of industry, especially<br />
mining, can results in the transfer of<br />
arsenic to air, water and soil<br />
©Loukola-Ruskeeniemi, Arseeni Suomen luonnossa<br />
ympäristövaikutukset ja riskit, 2004<br />
24.10.2012 6
<strong>ARSENAL</strong> – Arsenic Control<br />
in Mining Processes and Extractive Industry<br />
NEEDS<br />
Arsenic is commonly concentrated in sulfide-bearing mineral deposits, especially those associated<br />
with gold mineralization, and it has a strong affinity for pyrite, one of the more ubiquitous<br />
minerals in the Earth’s crust. It is easily solubilized in water phase and highly depend on prevailing<br />
conditions. Therefore the control and management of arsenic in all mining operations is a<br />
necessity.<br />
APPROACH<br />
• New mineral processing and water treatment solutions for arsenic removal<br />
• Novel bio-based treatment processes for arsenic containing wastes and streams<br />
• Monitoring and environmental risk assessment tools<br />
BENEFITS<br />
• Better knowledge and new management tools on arsenic in the mining environment<br />
• Eco-efficient solutions for mining industry to control and remove arsenic<br />
• Minimization of health and environmental risks related to arsenic<br />
COMPETITION<br />
• Arsenic is a world-wide challenge – globally over 10 Million people potentially exposed to<br />
arsenic through drinking water alone<br />
• Arsenic behavior is highly depend on prevailing conditions and processes and therefore<br />
requires tailor-made approaches - Special solutions and a global approach are a challenge and<br />
a possibility.<br />
24.10.2012 7
WASTE WATERS<br />
MINING ACTIVITIES<br />
Open pit<br />
Underground<br />
TAILINGS IN MINING AREA<br />
Overburden<br />
Drainage waters<br />
ORE<br />
Waste rock<br />
•Mapping of technologies for<br />
arsenic monitoring and<br />
identification<br />
•Development of technologies for<br />
arsenic removal from mine waters<br />
•Improvment of water recirculation<br />
Process waters<br />
Flotation<br />
EXTRACTION<br />
MINERAL PROCESSING<br />
Crushing, Grinding and<br />
Classification<br />
Physical separation<br />
methods<br />
Gravity and magnetic<br />
separation<br />
•Characterization of arsenic<br />
containing ores and waste rocks<br />
•Study of the environmental<br />
effect of arsenic bearing dust<br />
and its dispersion to water and<br />
sediment.<br />
Hydrometallurgy<br />
Tank leaching<br />
Heap leaching<br />
Environmental impacts of<br />
arsenic containing tailings is<br />
minimized<br />
Tailings<br />
Leaching residue<br />
•Development of novel mineral processing<br />
methods and improvment of traditional mineral<br />
processing methods to control/remove arsenic<br />
in beneficiation process<br />
Raisa Neitola, GTK Mintec<br />
PRODUCT<br />
Concentrate<br />
Concentrate in which the<br />
arsenic concentration is<br />
minimized<br />
•Characterization of tailings,<br />
leaching residues and other wastes<br />
•Investigation of stability and<br />
solubility of arsenic in tailings<br />
•Transportation modelling of arsenic<br />
•Environmental risk assessment<br />
24.10.2012 8
ARSENIC REMOVAL TECHNOLOGIES<br />
Method Content Objectives<br />
MINERAL<br />
PROSESSING:<br />
FLOTATION<br />
SORPTION<br />
TECHNIQUES<br />
FOR WATER<br />
TREATMENT<br />
BIOPROSESSING:<br />
BIOLEACHING<br />
Laboratory scale study to find optimal<br />
flotation conditions for arsenic<br />
containing gold ores<br />
Lab-scale tests to find and apply costeffective<br />
sorption materials for Asremoval<br />
from mine waters<br />
Laboratory batch tests for side<br />
streams and waste materials<br />
Continuous leaching tanks for nickel<br />
concentrate in pilot-scale<br />
To produce high quality gold<br />
concentrate with very low<br />
arsenic grade and recovery<br />
To develop techniques for<br />
removal of trace level Asconcentrations<br />
as a polishing<br />
step before discharge to the<br />
environment<br />
To reduce the amount of<br />
released arsenic and minimize<br />
environmental impacts of<br />
arsenic containing streams<br />
and waste materials<br />
BIOPROCESSING:<br />
BIO-OXIDATION<br />
Fluidized-bed reactor for waste waters To stabilize arsenic binding it<br />
into the iron precipitate<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 9
MINIMAN – Solutions for Control of Nitrogen<br />
Discharges at Mines and Quarries<br />
• Timetable: 1.1.2012-31.12.2013<br />
• Total budget: ~ 900 000 euro<br />
• Research partners: GTK, VTT ja TTY<br />
• Industrial partners:<br />
– Mining industry: Outokumpu Chrome Oy, Agnico Eagle Finland Oy, Yara Suomi Oy,<br />
FQM Kevitsa Mining Oy, Nordic Mines AB, Nordkalk Oy Ab<br />
– Stone industry: Infra ry, Kiviteollisuusliitto ry<br />
– Technology providers: Outotec (Finland) Oyj, Kemira Oyj, Ekokem-Palvelu Oy<br />
– SMEs: BK-automation Ky<br />
• International collaboration:<br />
– CSIRO<br />
– Univerisity of Luleå<br />
• Other Collaboration:<br />
– Pohjois-Suomen AVI (Regional State Administrative Agency of Nothern Finland)<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 10
MINIMAN – Solutions for Control of Nitrogen<br />
Discharges at Mines and Quarries<br />
NEEDS<br />
• Better understanding of the behaviour of<br />
nitrogen compounds<br />
• Minimizing of nitrogen transport<br />
• Removal of N-compounds from mine waters<br />
APPROACH<br />
• Analysis of sources, behaviour and management<br />
opportunities of nitrogen compounds<br />
• Biological reactor process and electrochemical<br />
/adsorption process for nitrogen removal<br />
BENEFITS<br />
• Knowledge, tools and technological solutions<br />
for nitrogen control at mines<br />
• Users: Technology companies, mines, consults,<br />
authorities, other stakeholders<br />
COMPETITION<br />
• Non-nitrogen explosives/explosion techniques (not in near future)<br />
• Use of membrane solutions for water treatment<br />
Challenges<br />
• Behaviour and release of nitrogen<br />
compounds from waste rock and<br />
tailings<br />
• Water: Relatively low (NO 3- ,<br />
NH 4+ ) concentrations, high<br />
volumes, high ionic<br />
concentrations, Nordic conditions
NITROGEN SOURCES IN MINING AREA<br />
• The major nitrogen sources at<br />
mine sites<br />
– Ammonium nitrate based<br />
explosives<br />
– Cyanide used in gold extraction<br />
• The minor sources of nitrogen in<br />
mine waters and wastes include:<br />
– Use of HNO 3<br />
• pH regulating agents<br />
• in acid washing of activated<br />
carbon used in gold recovery<br />
– Use of ammonia as lixiviant in<br />
copper and nickel<br />
hydrometallurgy<br />
Explosion<br />
fumes to air<br />
Final product<br />
•Gases: N 2 , NOx<br />
Mined ore<br />
and waste<br />
rock<br />
Spillage to<br />
surface and<br />
groundwater<br />
•Ions : NO 3- , NH 4<br />
+<br />
•Remnants of<br />
explosives to the<br />
extraction facility →<br />
tailings<br />
•Remnants of<br />
explosives to the waste<br />
rock area → potential<br />
leaching<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 12
REMOVAL TECHNOLOGIES OF NITROGEN<br />
AND THEIR SUITABILITY<br />
Biological<br />
• Currently used<br />
• Effective, inexpensive<br />
• Temperature dependent<br />
Wetlands<br />
• Currently used<br />
• Natural and safe<br />
• Large area needed<br />
• Temperature dependent<br />
Electrochemical<br />
• Not dependent on<br />
temperature, pH,<br />
organic carbon, toxins<br />
• Easy to run periodically<br />
• Capture products<br />
• No chemical addition,<br />
no sludge<br />
• E consumption<br />
• Problems with Mg 2+ ,<br />
Ca 2+ , SO 4<br />
2-<br />
Adsorption<br />
• Simple<br />
• Relatively economic<br />
• Low temperature<br />
dependence<br />
• Selective and efficient<br />
removal<br />
• Suits large volumes of<br />
clean water<br />
• Capture products<br />
Evaporation & Aeration<br />
• High E consumption<br />
Membrane technologies<br />
• High E consumption<br />
• Pre-treatment<br />
Zero-valent metals<br />
• Only reduction<br />
• pH requirements
Thank You for Your Attention!<br />
Raisa Neitola, GTK Mintec<br />
24.10.2012 14
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