Assessment of the Possible Reuse of Extractive Waste Coming from Abandoned Mine Sites: Case Study in Gorno, Italy

Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of extracting raw material. The current study, therefore, focuses on testing the validation of a shared methodology to recover extractive waste from abandoned mines, and applies this methodology to a case study in Gorno, northwest Italy. The methods focused on: (1) analyzing the impact of tailings and fine fraction of waste rock (<2 mm) on plants (Cress - Lepidium Sativum) to assess usability of both as soil additive, and (2) recovering raw materials from tailings and coarse fraction (>2 mm) of waste rock, by means of dressing methods like wet shaking table and froth flotation. The results indicated that the fine fraction of waste rock and tailings did not have detrimental effects on seed germination; however, there was marked decrease in plant growth. As for the recovery of raw materials, the coarse waste rock samples, crushed to <0.5 mm, produced a recovery of Cd, Ga, and Zn—as much as 66%, 56%, and 64%, respectively—using the wet shaking table. The same samples when crushed to 0.063–0.16 mm and used for froth flotation produced a recovery of Cd, Ga, and Zn of up to 61%, 72%, and 47%, respectively. The flotation experiment on tailings showed a recovery of Cd, Ga and Zn at pH 7 of 33%, 6% and 29% respectively. The present investigation highlights the methodologies used for extracting raw materials from extractive waste.

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Reuse of extractive waste from an abandoned mine site: case study of Campello Monti, Italy

10.5194/egusphere-egu2020-16506 ◽

2020 ◽

Author(s):

Neha Mehta ◽

Giovanna Antonella Dino ◽

Iride Passarella ◽

Franco Ajmone Marsan ◽

Domenico De Luca

Keyword(s):

Plant Growth ◽

Raw Materials ◽

Fine Fraction ◽

Coarse Fraction ◽

Waste Rock ◽

Abandoned Mines ◽

Shaking Table ◽

Growing Media ◽

Mafic Complex ◽

Wide Range

The progress and prosperity have been based on finite mineral resources and fossil fuels. Sustainable development goals of the United Nations and the implementation of the Paris Agreement, resulted in the vast utilization of a wide range of minerals for green technologies such as low-carbon applications. The global demand for raw materials has increased during the last decades (Kinnunen and Kaksonen, 2019).In addition to clear economic and societal benefits, mining has also created environmental challenges via significant amounts of mining and quarrying waste termed as extractive waste. However, these wastes can be transformed into valuable secondary metal sources combining metals recovery and environmental management.&#160; &#160;The current study, focuses on reuse and recovery targeted on extractive waste from abandoned mines in Campello Monti. It is a small settlement of Valstrona village in the northern sector of Piemonte, (NW Italy). Geologically, the site is present in the ultramafic layers of mafic complex of Ivrea Verbano Zone and consists of anorthosites, gabbros, gabbro-norite, lherzolites, peridotites, pyroxenites, titanolivin. The area was exploited for nickel production from Fe-Ni-Cu-Co magmatic sulphide deposits from 1865 until 1940s. Currently, the area has waste rock and operating residues dumps.As, the extractive waste from Campello Monti has not been moved from 1940s and recovery trials have also not been performed. Our study dealt with: (1) reusing fine fraction (<2 mm) of waste rock as soil additive, and (2) recovering raw materials from coarse fraction (>2 mm) of waste rock and operating residues, by means of dressing methods like wet shaking table and magnetic fraction.The seed germination and plant growth experiments performed using Blok et al. (2008) showed no major detrimental impact on Lepidium sativum plants. Although the plant growth decreased to 31% after adding 45% of waste rock to sand and blonde peat mixture. However, by adding fertilizers this can be mitigated to certain extent.The coarse fraction of waste rock crushed to <0.5 mm showed recovery of Co, Cu and Ni as 53%, 42% and 66% using shaking table. Whilst, for the same size and dressing method operating residues depicted recovery of Co, Cu and Ni in the range of 55-76%. Whilst, the recovery of these elements varied from 35-41% for operating residues and waste rocks using magnetic separation. The micro-XRF mineral mapping of the concentrates obtained from both dressing methods demonstrated presence of pyroxene, pyrrhotite, olivine, magnetite, pentlandite and chalcopyrite.The present investigation highlights the methodologies used for obtaining raw materials from extractive waste. Thus moving from the linear economy patterns of mineral extraction to circular closed loops.References <ol><li>Blok, C., Perssone, G., and Wever, G. (2008). A practical and low cost microbiotest to assess the phytotoxic potential of growing media and soil. ISHS Acta Horticulturae 779: International Symposium on Growing Media. 10.17660/ActaHortic.2008.779.46.</li> <li>Kinnunen, P.H.-M., and Kaksonen, A.H. (2019). Towards circular economy in mining: Opportunities and bottlenecks for tailings valorization. J. Clean. Prod. 228, 153&#8211;160.</li> </ol>

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Abandoned mine sites as a source of contamination by heavy metals: A case study in a semi-arid zone

Journal of Geochemical Exploration ◽

10.1016/j.gexplo.2007.04.011 ◽

2008 ◽

Vol 96 (2-3) ◽

pp. 183-193 ◽

Cited By ~ 300

Author(s):

M.C. Navarro ◽

C. Pérez-Sirvent ◽

M.J. Martínez-Sánchez ◽

J. Vidal ◽

P.J. Tovar ◽

...

Keyword(s):

Heavy Metals ◽

Arid Zone ◽

Abandoned Mine ◽

Abandoned Mine Sites ◽

Mine Sites ◽

Semi Arid

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WATER POLLUTION BY ABANDONED MINE SITES; ACID MINE DRAINAGE; MINED LAND RECLAMATION

Mineral Resources Engineering ◽

10.1142/s0950609801000439 ◽

2001 ◽

Vol 10 (01) ◽

pp. 85-114 ◽

Cited By ~ 1

Author(s):

R. LEE ASTON

Keyword(s):

Water Pollution ◽

Acid Mine Drainage ◽

Mine Drainage ◽

Land Reclamation ◽

Abandoned Mine ◽

Acid Mine ◽

Abandoned Mine Sites ◽

Mine Sites

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Impact of Sodium Hexametaphosphate on the Flotation of Ultrafine Magnesite from Dolomite-Rich Desliming Tailings

Minerals ◽

10.3390/min11050499 ◽

2021 ◽

Vol 11 (5) ◽

pp. 499

Author(s):

Duong Huu Hoang ◽

Doreen Ebert ◽

Robert Möckel ◽

Martin Rudolph

Keyword(s):

Ultrafine Particles ◽

Raw Materials ◽

Low Cost ◽

Froth Flotation ◽

Open Circuit ◽

Ore Deposits ◽

Sodium Hexametaphosphate ◽

Low Grade ◽

Low Contrast ◽

The Impact

The depletion of ore deposits, the increasing demand for raw materials, the need to process low-grade, complex and finely disseminated ores, and the reprocessing of tailings are challenges especially for froth flotation separation technologies. Even though they are capable of handling relatively fine grain sizes, the flotation separation of very fine and ultrafine particles faces many problems still. Further, the flotation of low-contrast semi-soluble salt-type minerals with very similar surface properties, many complex interactions between minerals, reagents and dissolved species often result in poor selectivity. This study investigates the flotation beneficiation of ultrafine magnesite rich in dolomite from desliming, currently reported to the tailings. The paper especially focuses on the impact of the depressant sodium hexametaphosphate (SHMP) on the following: (i) the froth properties using dynamic froth analysis (DFA), (ii) the separation between magnesite and dolomite/calcite, and (iii) its effect on the entrainment. As a depressant/dispersant, SHMP has a beneficial impact on the flotation separation between magnesite and dolomite. However, there is a trade-off between grade and recovery, and as well as the dewatering process which needs to be considered. When the SHMP increases from 200 g/t to 700 g/t, the magnesite grade increases from 67% to 77%, while recovery decreases massively, from 80% to 40%. The open circuit with four cleaning stages obtained a concentrate assaying 77.5% magnesite at a recovery of 45.5%. The dolomite content in the concentrate is about 20%, where 80% of dolomite was removed and importantly 98% of the quartz was removed, with only 0.3% of the quartz in the final concentrate. Furthermore, the application of 1-hydroxyethylene-1,1-diphosphonic acid (HEDP) as a more environmentally friendly and low-cost alternative to SHMP is presented and discussed. Using only 350 g/t of HEDP can achieve a similar grade (76.3%), like 700 g/t of SHMP (76.9%), while obtaining a 17% higher magnesite recovery as compared to 700 g/t of SHMP. Interestingly, the proportion of hydrophilic quartz minerals ending up in the concentrate is lower for HEDP, with only 1.9% quartz at a recovery of 21.5% compared to the 2.7% of quartz at a recovery of 24.9% when using SHMP. The paper contributes in general to understanding the complexity of the depressant responses in froth flotation.

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