The effects resulting from modern mining often result in severe environmental harm despite efforts by mining companies to reduce the negative impact. Modern mining includes mining for metals and minerals needed by various industries to make the world more sustainable. Lithium mining, for example, suffers from serious public relations issues due to the negative effects resulting from mining, particularly in the drought-prone areas where much of today’s lithium extraction occurs.
The need to develop more sustainable lithium mining techniques stems from the metal’s vital role in the manufacturing of rechargeable batteries, particularly those used for electric vehicles (EVs). Given its relevance in making the world more sustainable, lithium mining companies have looked at ways to reduce the harm extraction does to the environment. While new technologies have yet to replace lithium in EV batteries, new sustainable lithium mining techniques are making the process more environmentally safe.
Sustainable Lithium Mining Techniques & Technologies
The explosion of EV manufacturing in recent years has resulted in an increased demand for Lithium, the lightest metal on the periodic table. With this increase in EVs and stationary energy storage for storing renewable energy from wind and solar, the market for lithium batteries looks set to increase by as much as tenfold by 2030. However, it’s not just the EV and lithium battery markets that are driving this demand for sustainable lithium mining. Over seventy products contain lithium as a primary component including certain types of glass, heat-resistant ceramics, medications, mobile devices, and more.
Yet the energy and resulting carbon emissions required, along with the amount of fresh water and land necessary for lithium extraction and processing, make it less sustainable. Lithium mining is necessary to decarbonize the world economy, while its production via conventional means often produces significant, albeit localized, environmental harm. There are three commercially viable lithium mining techniques currently being used to extract the metal, with various forms of direct lithium extraction looking particularly promising.
Three main lithium mining techniques used today and how they affect the environment:
- Hard rock mining:
- Results in carbon dioxide emissions of 15 tons for every ton of lithium extracted.
- Requires 170 m³ of water per ton of lithium extracted.
- Requires an area of 464 m² per ton of lithium extracted.
- Underground brine reservoirs:
- Results in carbon dioxide emissions of 5 tons for every ton of lithium extracted.
- Requires 469 m³ of water per ton of lithium extracted.
- Requires an area of 3124 m² per ton of lithium extracted.
- Geothermal brine sources:
- Results in no added carbon dioxide emissions.
- Requires 3 m³ of water per ton of lithium extracted.
- Requires an area of 1 m² per ton of lithium extracted.
As global demand has been estimated to increase nearly fivefold by 2050 from 2018 levels, direct extraction from geothermal sources is currently the most sustainable lithium mining method, though it’s limited as to where it can be utilized. While lithium extracted from geothermal brine sources comes from a proprietary process, the fact that it can be done without using evaporation ponds, fossil fuels or traditional hard rock mining techniques shows sustainable lithium mining is a real possibility. However, as there are just a few places on the planet where sustainable lithium mining from geothermal brines could occur, it’s important to look at other ways to directly extract lithium from other sources with greater efficiency.
Direct Lithium Extraction
The intensive use of water and time-consuming process make conventional lithium extraction methods unsustainable. Lithium mining using these established techniques usually results in the removal of only about half of the available lithium in any case, while also involving intensive chemical treatment. Alternatives to these methods are known collectively as direct lithium extraction, of which extracting from geothermal brines is just one method.
Direct lithium extraction technologies deal with both the environmental impact and technical limitations involved in traditional approaches to lithium extraction. Sustainability in the processes must include avoiding the use of open-air ponds for evaporation as these ponds take up a great deal of space and require lengthy periods of time so that a sufficient amount of water in the brine can naturally evaporate. Several proposed techniques are being developed to directly extract lithium in a sustainable manner.
Some direct lithium extraction techniques being researched include:
- Ion exchange resins: Known also as specific sorbents or ion sieves, this method involves resins that can easily absorb positively charged lithium ions from brines, even in low concentrations. It also normally uses freshwater or mixtures containing acids to produce sufficiently pure lithium solutions.
- Solvent extraction: Combining the bring with organic solutions or solvents such as ferric sulfide or tri-n-butyl phosphate. The brine that comes into contact with these substances transfers high proportions of positive lithium ions into the liquid which is then mixed during a liquid phase to remove these ions. Typically, referred to as liquid-liquid extraction, this method often requires altering the pH of the solution to move the lithium ions between phases of the process.
- Electro-membrane processes: Selective to either negative or positive lithium ions, these types of processes use membranes pushed by electrical fields to recover lithium.
- Nanofiltration: Similar to electro-membrane processes, nanofiltration uses mechanical forces, rather than electrical forces, to filter solutions through membranes to recover lithium.
- Electrochemical ion pumping: Also called electrochemically switchable ion exchange or electrochemical ion insertion, this technique is similar to the use of ion exchange resins because it uses specific materials to attract positive lithium ions. Often used in conjunction with ion-selective membranes, electrochemical ion pumping requires no chemicals, instead utilizing electrode materials within solutions containing fresh water to produce a diluted lithium chloride solution.
- Selective precipitation: Used in brines where the chemicals that are able to form multiple bonds have been largely removed, this method allows a high proportion of lithium ions to be removed by supplementing it with various phosphates.
Many of these processes act similarly to how conventional evaporation ponds work, though they utilize membranes or electricity to attract lithium ions. Similarly, other types of thermal-assisted processes that concentrate brine may use evaporators or distillation devices. These technologies, when sufficiently developed, will decrease the need for current unsustainable lithium mining methods. Being quicker and requiring an operational footprint that’s much smaller than conventional techniques, these methods will continue to evolve, providing the United States and other countries with a much more economical and sustainable lithium supply to meet future needs.
Sustainable Lithium Mining in the United States
The US Department of Energy (DOE) saw the urgency in ramping up production of lithium-based batteries, as much of the country’s lithium supply came from Australia, China, or South America. In mid-2021, the DOE announced policy changes that would scale up domestic lithium production. These actions looked to take advantage of US lithium reserves, which make up about 10 percent of those globally. Many of these measures involve partnerships between public entities like the DOE and other government organizations and private US companies.
These DOE efforts seek to:
- Assess the US battery supply chain in order to invest federal funds strategically to position the country to lead the global market for lithium-based batteries.
- Guarantee partners in the private sector using US taxpayer funds to support manufacturing processes and policies that encourage domestic job creation.
- Improve US manufacturing through cooperative agreements, grants funded by the federal government, and research and development agreements.
- Launch infrastructure projects at federal sites by providing any necessary technical assistance, including grants for energy storage.
- Procure sufficient energy storage from stationary batteries to completely support clean energy production by 2035.
- Provide financing from DOE loan programs for the country’s EV battery supply chain through loans to private manufacturers to establish, expand, and reequip facilities throughout the United States.
- Support for the current administration’s goals regarding decarbonization.
These actions are being implemented by the DOE and will include multiple organizations and departments within the federal government, including the Commerce, Defense, and State Departments.
Filter Systems for Sustainable Lithium Mining
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