Introduction
Mining and extraction activities are essential in the exploitation of earth minerals. As custodians of Earth, human beings have the responsibility to ensure that the planet remains viable for future generations. However, efforts to meet accepted environmental goals may create hazards to the existing ecosystems.
For instance, lithium mining aims to reduce dependence on fossil fuel engines, thereby facilitating the achievement of the greenhouse gas emissions levels projected in the Paris Agreement of 2015 (Wei et al.). However, the process of lithium mining results in environmental destruction, which could offset any gains made in other areas. This paper will discuss the process of mining lithium and its associated environmental impacts.
The Growing Demand for Lithium
The first step towards global decarbonization is a shift away from reliance on fossil fuels. Wei et al. note that 30% of all urban greenhouse emissions come from vehicular traffic powered by fossil fuels. In many countries, government policy has aggressively supported the development of electric vehicles (EVs) as a viable alternative to internal combustion engines. As such, EV development programs have been in rapid growth since 2010, with 2017 marking the first year in which more than 1 million EVs were sold globally (Harper et al. 75).
Kelly et al. estimate that more than 1 billion EV units will be produced over the 30 years from 2020 to 2050. Notably, typical battery EVs and plug-in EVs use lithium-ion batteries because of the high lithium content in their cathodes. Kelly et al. point out that more than two-thirds of the lithium currently extracted from deposits worldwide is used in EV batteries. While this is expected to accelerate the widespread adoption of electrically powered automobiles, there is concern about how the environment will respond to the ramped-up lithium extraction programs.
Lithium Sources and Extraction
Lithium naturally occurs in compounds rather than in its elemental form due to its high chemical reactivity. Exploitable lithium reserves are either in underground brine solutions or in a solid granitic rock formation called pegmatite with rich deposits of the mineral spodumene (Kaunda, 239). More than half of the world’s total lithium reserves occur as brine deposits in the lithium triangle that traverses portions of Bolivia, Argentina, and Chile in the desert salt plains of Salar de Uyuni, Salar de Olaroz, and Salar de Atacama, respectively (Zeng et al.).
Chile alone supplies more than a third of the world’s lithium demand. In addition, the US, Australia, and China have significant lithium deposits in brine or solid formations (Giglio, 48). This paper will focus on the environmental impacts of brine extraction in the lithium triangle, where a substantial percentage of the lithium used in electric battery cells is sourced.
Continental brine in the lithium triangle is extracted using evaporative technology. Vera et al. (151) note that underground brine is first pumped into open-air ponds where more than 90% of the water evaporates naturally, leaving a concentrated brine. Notably, half of the brine processing facilities using evaporitic technology for lithium extraction are located in the desert salt plains of the South American lithium triangle, where temperatures are typically very high (Vera et al. 151). The concentrated brine is transferred to an onsite refining plant, where impurities are dissolved out, and lithium chloride is precipitated as lithium carbonate through the controlled addition of externally sourced soda ash.
Copious amounts of fresh water are needed to dissolve impurities for extraction, dissolve sodium carbonate, generate steam, and wash impurities off lithium carbonate crystals. The final product at the onsite facility is usually lithium carbonate, which is transported for further processing. It takes between 18 and 24 months from the time continental brine is pumped out to the time the final product is obtained (Kaunda, 241). Thus, the process is usually continuous and unresponsive in the short term to any changes.
Adverse Environmental Impacts
Notably, one of the major environmental impacts of lithium extraction is the depletion of freshwater resources within ecosystems, particularly in areas already experiencing water stress. Vera et al. (157) note that the refining plants at Atacama and Olaroz consume between 20 and 50 tons of fresh water for every ton of lithium carbonate produced. Kaunda (243) reports that in the Salar de Atacama, groundwater levels have been declining at a rate of 1 meter per year since lithium mining began. In this region, more than 65% of the available freshwater is currently diverted to lithium mining exploits.
Giglio (50) adds that the aggressive groundwater extraction in the lithium triangle has disrupted the water cycle. In particular, underground water flowing in aquifer formations between the Cordillera region of South America and the ocean has been hijacked. Indigenous communities near mining operations have been the first to note the impact of mining on freshwater reserves. In certain areas of the lithium triangle, oases have begun to dry up, vegetation cover is retreating drastically, and water stress is increasing for both livestock and vegetation (Crawford et al. 325). Moreover, Giglio (50) points out that freshwater reserves may be salinized if freshwater discharge via pumping disrupts the natural balance between freshwater and saltwater underground reserves. As such, continued lithium extraction portends doom for the surrounding ecosystem.
The extraction of brine results in the existence of other metallic minerals that are largely considered waste. Kelly et al. note that, typically, 70% of the pumped-out brine is water, with only 0.17% lithium. Thus, during and after the brine concentration, there are considerable undesired minerals that arise. In evaporation ponds, certain minerals, such as boron and magnesium, are extracted, crystallized, and then piled into waste mounds next to the ponds.
Spent brine, in particular, is brine at the tail end of the refining process that is concentrated but devoid of any lithium (Vera et al. 152-156). As is the case in many extraction processes, the fate of spent brines is rarely discussed despite its importance from an environmental standpoint. As such, there is no conclusive and standard management of spent brines and waste mineral mounds, which are of no immediate importance to the mining company.
In some instances, spent brines are reinjected into wells, potentially introducing foreign elements that disrupt the existing ecosystems in the saline aquifer. Moreover, mining companies are unwilling to reinject the brine as it is likely to dilute the brine from production wells (Vera et al. 152). Nevertheless, the waste minerals could be impediments in the future should the Salars be required for other ecological or social uses.
Giglio (49) observes that countries such as Bolivia are affected by numerous internal socio-political problems that render efforts to have a comprehensive mining program impossible. The presence of Chinese and European interests has led to the prioritization of short-term interests, such as the development of mining infrastructure, over a long-term strategy that addresses environmental issues.
While EVs have a smaller carbon footprint than internal combustion engines from the date of production onward, they produce considerable greenhouse gas emissions during production. Melin (2) notes that an EV can have embedded emissions at the time of manufacture equivalent to the emissions made by an average diesel car in a period of up to seven years. Some of the embedded emissions in an EV arise during the pumping of underground brine to the surface. Giglio (50) notes that there is significant emission of carbon dioxide during the pumping of continental brine.
Kelly et al. highlight that producing 1 ton of lithium carbonate from brine results in the emission of 3.8 tons of carbon dioxide. Most carbon dioxide emissions are driven by the use of soda ash in the carbonization of lithium chloride. Thus, lithium extraction is accompanied by significant greenhouse gas emissions, which cannot be ignored, especially in the context of broader global environmental goals.
Moreover, lithium-ion battery packs are likely to become pollutants once their state of health is no longer significant. Harper et al. (76) observe that lithium-ion batteries have a 15-20-year lifespan, after which a decision must be made on whether to reuse or recycle them. Currently, there is sufficient demand for reuse activities to absorb the batteries nearing the end of their first use cycle. However, a significant crisis looms in the future management of lithium-ion batteries. One obvious solution to this problem is recycling batteries at the end of their useful life, which can produce one ton of usable lithium from 28 tons of lithium from used units (Harper 76). However, there is a significant problem in that the disassembly of used battery packs is inherently dangerous, as it can electrocute the technician or emit deadly carcinogenic gases.
Currently, there are no capacities for the effective and safe recycling of lithium-ion batteries. There is skepticism that enough personnel, or artificial intelligence constructs, will be equipped with the necessary skills when the huge number of lithium-ion batteries being produced for EVs today are retired (Harper, 77). It is therefore likely that the batteries will end up in landfills or other haphazard disposal sites, such as junkyards. In perspective, stable ionic lithium will have been extracted from more than 300 meters underground, used in batteries, and then discarded overland or in landfills, where it can contaminate water sources and harm flora and fauna.
Conclusion
In conclusion, lithium extraction has significant adverse environmental impacts. In the lithium triangle, where much of the world’s lithium is sourced, there is a risk of loss of freshwater underground reserves and increased desertification. Moreover, the overground by-product of lithium mining is mineral and elemental waste that should ideally stay underground. Soon, exhausted EV lithium-ion battery packs will become a significant source of solid waste, especially if efforts are not made to scale up recycling capabilities. To avoid such a scenario, a comprehensive redesign of the lithium mining and utilization program must commence forthwith.
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