www.smart-ground.eu This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 641988

SMART data collection and inteGRation platform to enhance availability and accessibility of data and infOrmation in the EU territory on SecoNDary Raw Materials

Characterization of secondary raw materials from mine waste: a case study from the Campello Monti Ni-Cu-Co±PGE mining site (Western Alps, Italy)

Piergiorgio ROSSETTI Giovanna Antonella DINO Giulio BIGLIA Emanuele COSTA

University of Torino, Dept. of Earth Sciences

Sardinia Symposium 2017 2 – 6 October 2017

S. Margherita di Pula, Cagliari, Italy

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Supply of Raw Materials – particularly, Critical Raw Materials - is fundamental

to maintain and develop EU economy. Considering their increasing scarcity and raising prices, recycling and recovery from urban, industrial and extractive waste disposal sites is important.

When considering mining of waste from disposal sites, actions that should be

forecasted to assess the sustainability of the mining opportunity include: o the estimation of the amount of types of waste materials o the characterisation and localization of the different wastes in landfill o their potential recovery and treatability for their utilization.

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Extractive waste

http://www.groundtruthtrekking.org/Graphics/Mining-terms.html

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of course… economic viability depends on a number of factors but a thorough characterization is fundamental

Top Star dump (RSA), 2008 – Ca. 2.7 tonnes of gold were recovered from the dump which has now been removed http://www.timeslive.co.za/

Why extractive waste? - already known commodities still present

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- resources which were not exploited in the past (e.g., feldspar from quarry dumps)

Ecomin plant (VB, Italy)

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- undiscovered/unexpected resources (REE, PGE, Li…)

Element concentration map of P, ΣREE, ΣHREE, and select REEs (Ce, Gd, and Tm) obtained by LA–ICP-MS from the Love Hollow phosphorite, Arkansas. Note the uniform REEs distributed in the francolite grains.

Emsbo et al., 2015

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Case study: Campello Monti mining area, NW Italy

A thorough characterization study is therefore fundamental

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Geological setting

Mineralizations: Fe-Ni-Cu(-Co) sulphides within the “Mafic Complex” of the Ivrea Verbano Zone, in deep-seated layered intrusions intruded in a metasedimentary sequence strongly localized PGE (platinum-group elements) enrichments

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100 m

upper Strona Valley, 1300 – 1600 m asl

Location

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mine adits

dressing plant Armando & Sabbadin, 1976

Historical data

Orebodies lens-shaped sulphide-rich bodies within pyroxenites

Mining activity 1865 – 1945 Exploited for Ni (1-2% to 0.5%) 5-6% Ni concentrate (flotation)

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1: Preliminary (reconnaissance) survey

Preliminary (reconnaissance) survey

to verify location and typologies of extractive waste facilities

with the help of a handheld X-ray fluorescent analyzer

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Recognition of 2 types of waste materials: - waste rock - operating residues

Selection of 8 waste deposits: 6 waste rock 2 operating residues

1: Preliminary (reconnaissance) survey

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1: Preliminary (reconnaissance) survey

1

1

8

operating residues

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1: Preliminary (reconnaissance) survey

3 waste rock

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2: Sampling

sampling protocol manual sampling (hand shovel) following a grid method. Each sample (8-10 kg) was collected in an area of 1.5 m2 after cleaning from organic residues For each sample point: operator date UTM WGS84 coordinates type of material photos notes etc.

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Samples processing protocol

3: Laboratory: 1. Samples processing

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• ICP-MS multielements analysis (general geochemical screening)

• ICP-OES for samples with a content of some metals (Ni and/or Cu)

exceeding the upper limit for the previous analytical package (5,000

and 10,000 ppm, respectively)

• Fire Assay - ICP-MS analysis of Au, Pt and Pd of samples strongly

enriched in Ni and Cu

• NiS Fire Assay – INAA analysis of Pt, Pd, Os, Ir, Ru, Rh, Au and

Re of selected samples among those strongly enriched in Ni and Cu

Preliminary analyses on samples of the three size classes (>20 mm, 20-2 mm, <2 mm). As

differences were not significant, geochemical analyses were performed on the whole sample.

3: Laboratory: 2. Geochemistry

whole-rock geochemistry

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1: very strong Fe, Ni, Cu, Co, ±PGE enrichments

3, 4, 8: strong Fe, Ni, Cu, Co (±PGE) enrichments

2, 6: moderate Fe, Ni, Cu, Co enrichments

2, 6: relatively low Fe, Ni, Cu, Co values

“waste” material is significantly enriched in Fe, Ni, Co and locally PGE

Metals enrichments are not uniform: 4 composition groups are identified

3.2 - Geochemistry: results

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I

II

III IV

ppm

Ni >10,000 Cu >5,000 Co >600

Ni 2,000÷10,000 Cu 600÷1,500 Co 100÷300

Ni 700÷1,600 Cu 200÷600 Co 100÷200

Ni 100÷700 Cu 50÷200 Co 50÷100

3.2 - Geochemistry: results

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3.2 - Geochemistry: results - PGE

PGE: highly variable (Pd+Pd: 5.8 to 821 ppb) Strong enrichments in operating residues from area 1 (PGEtot up to 1213 ppb) Strongly localized enrichments in waste rock samples (PGEtot up to 170 ppb)

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Mineralogical characterization

Petrographic characterization

metals (Ni, Co…) can be contained in ore minerals, like sulphides … or in silicates, like olivine

ore minerals can be coarse-grained … or occur in very fine-grained, complex intergrowths

200 µm

10 µm

3: Laboratory: 3. Mineralogy & petrography

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electron microscopy Ni and Co in pentlandite (Fe,Ni)9S8: 33 wt% Ni, 1.4% Co Cu in chalcopyrite CuFeS2: 34.5 wt% Cu

3.3 - Mineralogy & petrography: results

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po

pn

po

pn cpy

Fe as pyrrhotite Fe1-xS (not an ore mineral)

pentlandite (Fe,Ni)9S8

chalcopyrite CuFeS2

pentlandite and chalcopyrite mostly occur as granular, relatively coarse-grained ore minerals: suitable for mineral dressing

3.3 - Mineralogy & petrography: results

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Operating residues of area 1:

1 mm

0.4 mm

same material milled and metals-enriched, strongly oxidized

Operating residues of area 8: coarse-grained sorted ore material

3.3 - Mineralogy & petrography: results

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Conclusions - waste materials from the Campello Monti mining area often show strong Ni,

Cu and Co enrichments

these metals not only occur well above the typical rock content, but also within minerals (metal sulphides) which are suitable for metals recovery

- the metals distribution in the waste from the former mining area is not homogeneous, but strong differences occur among different waste deposits

each deposit shows a relatively homogeneous “geochemical signature”, depending on its significance within the mine site

Ni, Cu and Co represent potential SRM in the mineral waste from the mining area

Conclusions - 1

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- Such variability likely represents a factor typical of mine-related waste

As a consequence, detailed information on the primary ore deposit and on the former mining/ dressing activities is important for any evaluation study

- the multidisciplinary methodology tested in the Campello Monti area can be adopted also in other former mining sites

A thorough characterization of each waste deposit is a prerequisite for any resource evaluation. An in-depth characterization is one of the key factors to assess the resource potential, other factors including the site location, waste tonnage, as well as environmental and social aspects of landfill mining

Conclusions - 2

Project Coordinator Marco de la Feld

ENCO s.r.l. m.delafeld@enco-consulting.it

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