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Lithium and Cobalt Mining
A Segue into Mining
The primary ingredients in Li-ion batteries are lithium and cobalt. Both are considered critical materials, which the United States deems necessary for energy and/or defense but at risk of supply disruptions.
Lithium: Mining Brines
Half of the world's known reserves of lithium are found in an uplifted salt flat bordering Chile and Bolivia. In 2012, two of Chile's mines dominated world production. A lithium-bearing mineral, spodumene (LiAlSi2O6), can be mined from intrusive igneous rocks (introduced in this module's Unit 1 and reinforced in Unit 5), but lithium minerals (lithium carbonates and lithium chlorides) that crystallize from brines (very salty water) are cheaper and easier to extract. For example, a brine exists beneath the solid salt surface at the Salar de Uyuni in Bolivia and below the solid salt surface of the Salar de Atacama in Chile. This brine just needs to be pumped to the surface, dried, and then the minerals must be separated.
Sedimentary processes form the brines. These processes were introduced in Unit 1 of this module and will be reinforced in Unit 4.
- Lithium ions are derived from chemical weathering of volcanic rocks (or possibly from degassing of underground magma chambers). These ions (along with others) are carried by streams to seas (salt lakes). Not all brines will contain high levels of lithium simply because volcanic rocks are not found in all places.
- High evaporation rates will concentrate ions in the water, so brines containing more lithium will tend to be found in places with higher evaporation rates (deserts). For example, the annual rainfall in the Atacama Desert is only 15 mm (about 0.6 inch).
Mining concerns (for lithium brine). Whether or not mining will happen depends on a variety of factors, including:
- Overall concentration of lithium. If concentrations are higher than the cutoff grade, then mining can ensue. (The cut-off grade is the minimum concentration of ore that must exist in order for mining to be profitable.)
- Overall amount of mineable brine. Mining requires a significant upstart cost (for, in the case of lithium brine, evaporation ponds, lithium carbonate processing plants, potash processing plants, road development, energy and water infrastructure, etc.), so there must be enough total lithium to make up these costs.
- Composition of the brine. Magnesium is harder to separate from lithium, so high concentrations of magnesium ions increase mining costs. However, high concentrations of other sellable ions (such as potassium) could increase company revenue. For example, Sal de Vida (Chile) has a Mg : Li of 2.2, Salar de Atacama has a Mg : Li ratio of 4, and Salar de Uyani has a Mg : Li ratio of about 15. Based on the brine composition, mining should be most profitable in Sal de Vida.
- Other. Land availability, permits, access to roads, water, labor, etc. will determine if mining can happen. Large-scale mining is a relatively new activity in Salar de Atacama, primarily because of a lack of infrastructure and its remote location.
Environmental and other concerns of lithium brine mining. Brine mining is more environmentally benign than metal mining (described below) but nonetheless has environmental concerns, including:
- Footprint: land cannot be used for other things (pasture, salt harvesting by indigenous people)
- Lithium compounds are alkaline; breathing the dust can cause respiratory disorders.
- Brines are often transported elsewhere for processing. Many brines mined in the Chilean deserts are processed at sites on the coast and then exported to the United States for further refinement.
Table of Lithium Amounts Country Average concentration (% Li) Amount of resource (Million tons Li) Uyani Bolivia 0.0532 10.2 Atacama Chile 0.14 6.3 Kings Mountain Belt* North Carolina, USA 0.68 5.9
Discussion point: *The King's Mountain Belt is an igneous deposit of lithium. And, while the deposit has a relatively high concentration of lithium, mining operations in North Carolina were suspended in 1991 (although processing still happens in the region). Therefore, igneous deposits must have different cutoff grades than brine deposits. In addition, an igneous deposit in China (Jiajika) is mined although its lithium concentration is 0.59 (Gruber et al., 2011), thus implying that cutoff grades for igneous deposits in different places (like these in the United States and China) have different cut-off grades. Students can discuss why the cutoff grades vary.
Photos from the references below can be used to view examples of lithium brine mining.
Cobalt: An Example of More Conventional Metal Mining in Idaho
Note: Most cobalt mining happens in Africa. There is an example of how to use the Unit 2 concept map dealing with cobalt and the wars in Congo. The mining example below deals with historic and proposed mines in the United States.
The Blackbird Mine in Idaho
The Blackbird Mining District in Idaho houses the largest deposit of cobalt in the United States. Mining at the Blackbird Mine peaked in the 1960s; it closed in 1982 and became a Superfund Site. The main pollution problem was acid mine drainage. "Acid rock drainage from the waste rock piles, the underground workings, the tailings impoundment, and tailings deposited along area creeks have resulted in the release of elevated levels of hazardous substances to the environment (groundwater, surface water, soils), including but not limited to copper, cobalt, and arsenic. These releases have contributed to the elevated levels of dissolved copper and cobalt in Panther Creek and its tributaries. Contaminated soil, sediments, water rock, and tailings were also released from the Blackbird Mine site during high water flows from thunderstorms and snowmelt and deposited in soil along the banks of downstream creeks. Investigations showed that irrigation also spread contaminated material along Panther Creek in the over-bank soil as well as pastures. The fisheries and aquatic resources downstream of the Blackbird Mine have been impacted by arsenic, copper, and cobalt releases." (Office of Environmental Cleanup, 2003)
Questions for discussion (see graphs and figures to the right): Peak mining activities at Blackbird Mine happened in the 1960s. What happened to the amount of salmon breeding in Panther Creek during this time? What clues suggest that mining impacts the pH of water? What happens to the concentrations of metals dissolved in water when the pH changes?
New Cobalt Mining in the Panther Creek Area
Cobalt mining will resume in the area once the Idaho Cobalt Project finishes constructing its new underground mine (see the website linked below for photos of the mine construction). There will be a nearby mill and the concentrate will be shipped to a cobalt production facility located in state. The rocks are broken underground and brought to the surface. In the mill, rocks containing the metal ore are broken into fine particles, and then a process called flotation separates desired minerals (in this case, copper, gold, and cobalt) from other minerals.
Waste rock, the rock that does not contain ore but that is smashed and brought to the surface during mining, will be used to fill the underground tunnels after mining. In the meantime, the waste rock will be piled on site.
Metal mining typically produces a lot of waste. The proposed Idaho mine, for example, will produce 32 dry tons of concentrate (the cobalt, gold, and copper mixture that will be sent to the production facility) and 768 dry tons of tailings (the pulverized rock particles that are the byproduct of flotation). Some of the tailings will also be used to backfill the mining tunnels. The others will be stored in lined tailings ponds (water cannot escape through the liners but is instead drained by a included system). Once full, the tailings will be capped, and covered with soil and vegetation.
The water from the tailings and from the processing facility will be stored in a lined, on-site pond until they are cleaned in an on-site water treatment plant. The water can then be reused in the processing facility or released into Big Deer Creek.
Once mining operations cease, the land will be reclaimed. The water storage pond will be drained, graded (to look like the natural surroundings), and covered with soil and vegetation. The mill buildings will be demolished and removed. The waste rock piles will be removed and the rock used to fill the tunnels. Any unnecessary roads will be removed. Ideally this process of reclamation will return the land to its pre-mining state.
Mining concerns. The success of mining depends on a variety of factors, including:
- The concentration of ore. These metal ores will also have cut-off grades below which the mine will not be economically viable.
- Total amount of metal. The Idaho Cobalt Project estimates that there is enough metal to allow for 10--12 years of mining an estimated 3.3 million pounds of cobalt, 3 million pounds of copper, and 4000-5000 ounces of gold per year.
- Environmental safeguards. Mining sulfide metals, such as those at this Idaho site, can lead to acid mine drainage and the pollution of groundwater and surface water. The mine must be designed to minimize the risk of water pollution. The mine must monitor surrounding water to make sure that mining is not impairing water quality.
- Cobalt production (done elsewhere in the state) must be done in a way that minimizes air pollution, and uses energy and water responsibly.
- Other: access to energy, water, labor, etc.
Environmental and social concerns of the new cobalt mine include:
- Footprint. The mine activities will disturb about 135 acres of land, which can impact ecosystems, the wilderness, recreational activities such as hunting and fishing, and possibly industries such as timber.
- Noise and air pollution from heavy equipment and mining operations.
- Acid mine drainage from waste rock and tailings. When single-celled organisms metabolize sulfur in the sulfur-bearing minerals, they alter the pH of the water to make it very acidic (low pH). The acidic water more readily dissolves heavy metals (such as arsenic, chromium, and lead). Aquatic ecosystems are affected both by the low pH and the high levels of heavy metals. The problem is even worse because the surrounding rocks contain no carbonate minerals (carbonate minerals, such as the calcite and dolomite found in limestone, neutralize acid).
- Panther Creek drainage has historically supported runs of chinook salmon and steelhead trout. Three fish species, chinook salmon (Onchorynchus tshaqytscha), Snake River steelhead (Onchorynchus mykiss), and Columbia Basin bull trout (Salvelinus confluentus) living in these streams are listed as threatened by the Endangered Species Act.
References and Resources
Reuter's Photoblog on Lithium (April 4, 2013).
Gruber, Paul W., Medina, Pablo A., Keoleian, Gregory A., Kesler, Stephen E., Everson, Mark P., and Wallington, Timothy J. 2011. "Global Lithium Availability: A Constraint for Electric Vehicles?" Journal of Industrial Ecology 15, no. 5: 760--75.
Mebane, C. A. 1994. "Preliminary Natural Resource Survey---Blackbird Mine, Lemhi County, Idaho. U.S." National Oceanic and Atmospheric Administration, Hazardous Materials Assessment and Response Division, Seattle, WA. 130 pp. https://www.researchgate.net/publication/259288558_Preliminary_Natural_Resource_Survey_-_Blackbird_Mine_Lemhi_County_Idaho?channel=doi&linkId=549b04860cf2b80371371824&showFulltext=true
Office of Environmental Cleanup, EPA Region 10. 2003. "Blackbird Mine Superfund Site Record of Decision." Available online at http://www.bostonchemicaldata.com/EPAROD/BlackbirdmineRODID.pdf
Bergquist, Berit A., Hennessy, Daniel P., Salazar, Sandra M., Perkowski, Ben, Starkes, Jim, Sturim, Richard E., and Yakymi, Susan M. .1995. Blackbird Mine. In Coastal Hazardous Waste Site Reviews, edited by Beckvar, Nancy, Garman, Gayle and Harris, Lori. NOAA, ORCA and HAZMAT.
Idaho Fish and Game Department. "Chinook Redd Counts for Spawning Ground Report." This searchable database can be used to find updated Chinook redd counts in Panther Creek..