REMEDIATE

Reuse of extractive waste from abandoned mine site to restore land sustainability: A case study in Campello Monti, NW Italy

Neha Mehta, Giovanna Antonella Dino, Iride Passarella, Franco Ajmone Marsan,

Domenico Antonio De Luca

19 Sep 2018, Belfast

Mining

Treatment

Mining site

Ore

Minerals

Waste rock

Operating residues

Methodology Environmental impacts Reuse ConclusionsBackground

Extractive waste

Analysis of approximately 1000 abandoned mines across

globe, revealed that 75% of the closed mines had

resources left.

Extractive waste dumps at abandoned mine sites are

sources of contamination but also source of raw materials.

Management of extractive waste requires reducing

environmental impacts along with possible beneficial use.

Work provides holistic approach including geology, soil

chemistry and circular economy. Census of abandoned extraction

sites in Italy (APAT 2006)

Methodology Environmental impacts Reuse ConclusionsBackground

Management

of waste

Site investigation

Resource efficiencyAssessment of

environmental impacts and

human health

Risk analysis

Dressing activities and

analysis

Mobility studies

Total metal concentration

yes

no EW facility exploitation

with benefits

Remediation (exploitation

not beneficial)

Extractive waste

characterization

Extractive waste facility

Presence of harmful

impacts at site

No intervention activity ( onlymonitoring)

yes / no

Reuse

meth

odolo

gy

Background Methodology Environmental impacts Reuse Conclusions

The present study was conducted at

abandoned mining site in Campello Monti,

Piemonte in north west Italy.

Campello Monti (old dressing plant)

Waste rock dump – Campello Monti

Background Environmental impacts

Site settingReuse ConclusionsMethodology

Geographicallocation

Campello Monti is in Italian region of

Piedmont.

Geological Setting

Mafic formationintruded by mantle

peridotites.

Minerals:Chalcopyrite,

pentlandite, pyrrhotite

Hydrography and Hydrogeology

Strona stream

Groundwatercirculation : in fractured rocks, in waste dumps and in mining tunnels

used for extracting metal.

Exploitation activity

About fifteen small Fe-Ni-Cu-(Co) sulphidedeposits occur, in the

area comprised between the Sesia and

Strona valleys.

Nickel exploitationoccurred from 1865 to

1943.

Background Environmental impacts

Site settingReuse ConclusionsMethodology

Background Environmental impacts

Sample locationReuse ConclusionsMethodology

Water samples were found to be

contaminated by Ni.

Soil samples showed Cr, Cu and Ni

contamination.

Waste rocks (<2 mm) showed

concentrations of Co, Cr, Cu and Ni

exceeding the Italian permissible

limits.

Photo taken during water and waste rock sample

collection

Water

Waste rock

Background Environmental impacts

Total concentrationsReuse ConclusionsMethodology

Superficial layer Campello Monti Campello Monti

human health risk Superficial layer Deep layer

Concentration at

source [mg/kg.

d.m.]

Carcinogenic Risk

(RI)

Hazard Quotient

(HQ)

Risk to

groundwater

(RGW)

Risk to

groundwater

(RGW)

Antimony 1.26 --- 0.04 0.05 0.01Arsenic 1.06 2.73 x 10-6 0.05 0.034 0.07Beryllium 0.05 3.28 x 10-11 3.51 x 10-4 1.6 x 10-4 3.2 x 10-4

Cadmium 0.03 1.74 x 10-11 9.62 x 10-4 9.46 x 10-4 1.9 x 10-3

Cobalt 18.9 --- 0.8 0.08 0.16Chromium (total) 160 --- 3.05 x 10-3 1.7x 10-5 3.4 x 10-5

Nickel 427 2.88 x 10-8 0.3 3.12 6.24Lead 2.6 --- 9.73 x 10-3 0.003 0.006Copper 173 --- 0.06 0.05 0.09Selenium 0.02 --- 5.26 x 10-5 3.77 x 10-3 0.006Thallium 0.01 --- 0.03 1.18 x 10-3 0.002Vanadium 1.25 --- 0.04 NA NAZinc 9.98 --- 4.37 x 10-4 5.1 x 10-4 1.02 x 10-3

Background Environmental impacts

Risk assessmentReuse ConclusionsMethodology

pH dependence batch leaching test were performed

to study release aspect of contaminants in water, to

further analyze impacts of waste.

Experimental conditions :

Liquid : solid = 10:1

pH = 4, 6, 8, 10, 12

Time = 24 hours

The eluates showed concentration of all the PTEs

analyzed within the permissible limits except Ni.

Background Environmental impacts

Leaching studiesReuse ConclusionsMethodology

Fine fraction was analyzed for its use as additive to soil.

Extractive waste was sieved to obtain the fine fraction (< 2

mm, sieve size)

Experiments were conducted on Lepidium sativum seeds.

Seed germination test

Background and

methodologyEnvironmental impacts Reuse as soil additive

(fine fraction < 2mm)Conclusions

Photos taken after 21 days of growth

Extractive waste was mixed with sand and

compost in different percentages and its effect on

final weight of plants was observed.

Background and

methodologyEnvironmental impacts Reuse as soil additive

(fine fraction < 2mm)ConclusionsBackground and

methodologyEnvironmental impacts

Coarse fraction of waste rocks

and operating residues

Jaw crusher

CrushingSieving

Different sieve sizes

Shaking table

Magnetic separation

Recovery

method

Recovery analysis ( by total metal

content and mineralconent)

Background and

methodologyEnvironmental impacts Recovery from

coarse fraction (> 2mm)

Conclusions

Separates particles on the basis of difference in specific gravities (SG) of particles.

Sincere thanks to Prof. Paola Marini and Dr. Rossana Bellopede,

Politecnico di Torino, for their help for concentrator table and magnetic

separation experiments.

Wet shaking table

Schematic diagram

Background and

methodologyEnvironmental impacts Recovery from

coarse fraction (> 2mm)

Wet shaking table

Conclusions

Recovery % =𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑒𝑥.𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑒 𝑤𝑒𝑖𝑔ℎ𝑡

𝐹𝑒𝑒𝑑 𝑥.𝐹𝑒𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡. 100

Recovery of Co, Cu, Ni and Pd was higher for

size fractions (0-0.5 mm) than 0.5-1 mm.

Recovery % for Ni reached upto 76% for

operating residues.

Background and

methodologyEnvironmental impacts Recovery from

coarse fraction (> 2mm)Wet shaking table

Conclusions

Manual magnetic separation to see the recovery of different

fractions.

Dry low intensity magnetic drum for 0.5-1 mm fraction.

High gravity magnetic separator for 0.063-0.25 mm, 0.25-0.5

mm.

Schematic diagram of High

gravity magnetic separator

Background and

methodologyEnvironmental impacts

Recovery from

coarse fraction (> 2mm)

Magnetic separation

Conclusions

Arsenic was found to cause carcinogenic risk. Ni caused risk to groundwater.

Waste from Campello Monti did not prove harmful to plant growth.

Up to 76% recovery for Ni through wet shaking table.

Up to 52% recovery for Co and Ni through magnetic separation.

The present research shows that the followed approach can be used at otherabandoned mine sites in order to decrease environmental impacts whilegenerating economic benefits.

Background Methodology Environmental impacts Reuse Conclusions

Thanks For Listening

REMEDIATE

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 643087

Project coordinated by the QUESTOR Centre at Queen’s University Belfast www.qub.ac.uk/questor