minerals Article Potential of Tailing Deposits in Chile for the Sequestration of Carbon Dioxide Produced by Power Plants Using Ex-Situ Mineral Carbonation Oscar Marín 1,2,* , José O. Valderrama 1, Andrzej Kraslawski 2,3 and Luis A. Cisternas 1,* 1 Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta, 1240000 Antofagasta, Chile; [email protected] 2 School of Engineering Science, Lappeenranta-Lahti University of Technology (LUT University), FI-53851 Lappeenranta, Finland; andrzej.kraslawski@lut.fi 3 Faculty of Process and Environmental Engineering, Lodz University of Technology, ul. Wolczanska 213, 90-924 Lodz, Poland * Correspondence: oscar.marin.cortes@lut.fi (O.M.); [email protected] (L.A.C.) Abstract: In this study, the potential of copper tailing deposits in Chile for the sequestration of carbon dioxide (CO2) via ex-situ mineral carbonation integrating the recovery of valuable metals was assessed. An inventory of tailing deposits and CO2 sources existing in Chile was constructed to determine the most suitable site for the installation of a future mineral carbonation plant and to evaluate the technical, economic, and environmental feasibility of CO2 capture, separation, and transport from the source to the mineral carbonation plant. The data of the inventory of tailings deposits in Chile were obtained from the National Service of Geology and Mining. For the thermo- electric plants installed in Chile, data of energy production were obtained from the Energy National Citation: Marín, O.; Valderrama, J.O.; Commission. Through the use of the technique for order preference by similarity to ideal solution Kraslawski, A.; Cisternas, L.A. Potential of Tailing Deposits in Chile (TOPSIS) method and sensitivity analysis, the optimum location in the region of Antofagasta to for the Sequestration of Carbon install a mineral carbonation plant was identified. In addition, the results show that in the region Dioxide Produced by Power Plants of Antofagasta five tailing deposits have the potential to sequester between 66 to 99 Mt of CO2. Using Ex-Situ Mineral Carbonation. Meanwhile, thermoelectric plants in 2018 produced about 9.4 Mt of CO2 that is available to be Minerals 2021, 11, 320. https:// sequestered, with a maximum generation potential of 21.9 Mt of CO2eq per year. The methodology doi.org/10.3390/min11030320 and the study presented can be considered as a preliminary study to identify tailings that require further analysis. Academic Editors: Mamadou Fall and Tuncel M. Yegulalp Keywords: mine tailing deposits; CO2 sequestration; mineral carbonation; mining waste Received: 14 January 2021 Accepted: 17 March 2021 Published: 19 March 2021 1. Introduction Publisher’s Note: MDPI stays neutral The release of large amounts of greenhouse gases (GHGs) as a result of intensive with regard to jurisdictional claims in human activities has contributed to global warming [1]. This warming occurs due to the published maps and institutional affil- presence of GHGs, which absorb the energy that would otherwise have escaped out into iations. space, producing an increase in global temperature. Among the most important GHGs are CO2, CH4,N2O, SF6, hydrofluorocarbon (HFC), and perfluorocarbon (PFC), which were defined by the United Nations in the Kyoto Protocol. Of these gases, CO2 has been reported to be the main substance of anthropogenic origin that increases the greenhouse effect [2]. For this reason, several technologies have been developed as measures to mitigate CO Copyright: © 2021 by the authors. 2 Licensee MDPI, Basel, Switzerland. emissions, either reducing anthropogenic CO2 emissions or capturing and sequestering This article is an open access article atmospheric CO2 [3]. distributed under the terms and Within the technologies used for mitigation are the renewables energies, which are not conditions of the Creative Commons completely free of emissions. Shrestha et al. [4] reported the average GHG emission rates Attribution (CC BY) license (https:// estimated from several published studies on renewable energy processes. The emissions creativecommons.org/licenses/by/ determined for the renewable energy sources in g CO2eq/kWh are: 86 for biomass, 71 for 4.0/). solar (solar photovoltaic), 67 for geothermal, 31 for wind, and 25 for hydroelectric. For Minerals 2021, 11, 320. https://doi.org/10.3390/min11030320 https://www.mdpi.com/journal/minerals Minerals 2021, 11, x FOR PEER REVIEW 2 of 21 Minerals 2021, 11, 320 2 of 21 for solar (solar photovoltaic), 67 for geothermal, 31 for wind, and 25 for hydroelectric. For non-renewablenon-renewable energies energies (coal, (coal, oil, natural oil, natural gas, gas,and andnuclear), nuclear), average average emissions emissions are 1023, are 1023, 780,780, 606, 606,and and14 g 14 CO g CO2eq/kWh,2eq/kWh, respectively. respectively. Despite Despite the increase the increase in the in use the useof renewable of renewable energiesenergies and andthe intensive the intensive search search for better for better ener energygy efficiency, efficiency, fossil fossil fuels fuels are still are stillpreferred preferred for energyfor energy generation generation due dueto their to their particular particular characteristics characteristics such such as high as high energy energy density, density, easyeasy use useand andstorage, storage, abundant abundant supply, supply, and, and, most most attractive, attractive, their their relatively relatively low lowcost cost[5]. [5]. However,However, the combustion the combustion of fossil of fossil fuels fuels releases releases large large amounts amounts of CO of2 CO to 2theto atmosphere, the atmosphere, accountingaccounting for up for to up 65% to 65% of the of thetotal total gases gases expelled[6]. expelled [This6]. This situation situation will willcontinue continue to to increaseincrease globally, globally, so supporting so supporting technologies technologies for renewable for renewable energies energies have have to be to employed, be employed, suchsuch as CO as2 CO capture,2 capture, either either for long for long term term storage storage or for or reuse for reuse [7]. Within [7]. Within the technologies the technologies of carbonof carbon capture, capture, use, use,and andstorage storage (CCUS), (CCUS), mineral mineral carbonation carbonation (MC) (MC) is one is oneof the of themost most promisingpromising long long term term storage storage processes, processes, since since gaseous gaseous CO2 CO is fixed2 is fixed as a assolid, a solid, minimizing minimizing the riskthe riskof subsequent of subsequent leaks leaks into into the atmosphere the atmosphere [8,9]. [8 ,9]. MC MCoccurs occurs when when CO2 CO reacts2 reacts with with oxides, oxides, hydroxides, hydroxides, or silicates or silicates of calcium of calcium (Ca,), (Ca,), magnesiummagnesium (Mg), (Mg), and andiron iron(Fe) (Fe)to produce to produce geologically geologically stable stable carbonate carbonate species species and andsilica. silica. The Thefollowing following chemical chemical reaction reaction summarizes summarizes a family a family of reactions: of reactions: (Ca,(Ca, Mg, Mg, Fe)SiO Fe)SiO3(s)3(s)+ + COCO2(g)2(g) (Ca,(Ca, Mg,Mg, Fe)COFe)CO3(s)3(s) ++ SiO SiO2(s)2(s) + +heat heat Usually,Usually, MC MCis an isexothermic an exothermic and spontane and spontaneousous reaction reaction in which in conversion which conversion to car- to bonate is thermodynamically favored [10]. For example, for both Mg2SiO4(s) and CaSiO3(s) carbonate is thermodynamically favored [10]. For example, for both Mg2SiO4(s) and the reactions release 90 kJ/mol [5]. This process was proposed for the first time by Seifritz CaSiO3(s) the reactions release 90 kJ/mol [5]. This process was proposed for the first time Minerals 2021, 11, x FOR PEER REVIEW 3 of 21 [11] byto Seifritzimprove [ 11the] tonatural improve silicate the naturalweathering silicate process, weathering which process,has occurred which throughout has occurred the geologicalthroughout time the geologicalscale. time scale. The Thestability stability of the of theproducts products of the of the above above mineral mineral carbonation carbonation reaction reaction is is explained explained by by thethegive carbon carbon it a profit atom to beingbeing promote atat itsits the lowest lowest deployment energy energy level oflevel this in in the technology, the carbonate, carbonate, being which which able provides providesto achieve a storage a this storagelifethrough life of more of the more thanrecovery than 100 100 of thousand thousandvaluable years metals years [12 [12]. from]. This This mine technologytechnology tailings. Recently, is also attractive attractive Araya etbecause because al. [22,23] of of thetheinvestigated abundance abundance the in in techno-economicnature nature of of this this type feasibility of silicate,silicate, of withwithcritical thethe raw capacitycapacity materials toto sequester sequester recovery all allfrom the the COcop- 2 CO2emittedper emitted mine by bytailings the the processes processes in northern of of fossil fossilChile. fuel fuel They combustion co obmbustiontained [13 positive ].[13]. Mineral Mineral net carbonation present carbonation values is nothing isfor noth- the more pro- ing morethanduction athan process of arare process of earth natural of oxides natural wear and thatwear vanadium occurs that occurs on geologicalpentoxide on geological scales,(V2O 5scales,). and However, therefore and therefore to the analyze process the the is processextremelypotential is extremely of slow. a tailings,