The drive for new lithium extraction technologies
Lithium derivatives are sourced from either minerals or brines, with recycling not widely practiced yet. Minerals can be commercially treated to produce lithium hydroxide monohydrate or lithium carbonate. For brines, lithium chloride is initially produced as a solution which can then be processed by carbonation into lithium carbonate or dried to produce lithium chloride. It is not commercially viable to produce lithium hydroxide monohydrate directly from brines using conventional technologies.
The limitations of conventional technologies have led to the development of various emerging technologies that target improved extraction of lithium from brine and hard-rock resources. Due to the growth in demand and subsequent increase in the price of lithium compounds, technology developers are seeking to extract lithium from unconventional mineral and brine deposits, which historically would have been uneconomical.
The drive for new technologies in the brine and mineral-based sectors differs slightly. In the brine sector, the aim is not only to exploit uneconomic deposits but also to improve the environmental footprint of the mining (e.g., reduced land usage, reduced water usage, and reduced reagent consumption) or improve the efficiency of the process by improving lithium recovery or decreasing production time. In comparison, the only driver identified by NexantECA for mineral extraction technologies has been the exploitation of unconventional and historically uneconomical resources.
NexantECA - New lithium extraction technologies
There are several drivers behind the development of alternative lithium production processes to conventional brine. These include:
Eliminating or reducing the footprint of evaporation ponds. For example, a 20,000 ton per annum (tpa) LCE plant using solar beneficiation to concentrate salar brine requires approximately 500 to 1,000 hectares of ponds.
Decreasing production time. Evaporation rates have a direct impact on production for conventional processes. Brine beneficiation takes between 12 to 18 months from initial brine to final concentrate. Small increases in annual precipitation can cause months-long disruptions in the production of solar evaporated brines, as was experienced in the Atacama region in 2015.
Increasing lithium recoveries from 40 to 50 percent to over 80 percent. Emerging technologies report significantly higher recoveries of lithium over conventional brine beneficiation. Most lithium losses in conventional processes are due to co-crystallization of lithium salts with other compounds in the pond system.
Lower usage of fresh water. Consumption of fresh water can be a deciding factor when applying for a mining concession in regions with scarce water resources, such as Andean salars. Furthermore, there are concerns that the abstraction of large volumes of brine may have a wider impact on the hydrological systems within these regions. Many emerging technologies re-inject lithium-depleted brine, in theory, eliminating the potential hydrological impact of abstraction.
Lower reagent consumption and increased product purity (reduction of magnesium, calcium, and boron impurities). Utilizing direct lithium extraction (DLE) processes can reduce the concentration of impurity ions and, therefore, the quantity of reagents required for purification.
Exploitation of brines containing relatively low concentrations of lithium. This is especially relevant for geothermal brines, where the high temperature of the brine can be exploited in the lithium extraction process. Either to enhance the DLE step or to provide energy (geothermal) for downstream concentration of the lithium-enriched brine and precipitation of lithium carbonate.
Exploitation of brines with high impurity content. Conventional techniques for lithium extraction have been left wanting in lithium deposits with high concentrations of magnesium, such as the Salar de Uyuni in Bolivia or Zhabuye lake in China. While technically possible, the high reagent consumption required makes them uncompetitive. In comparison, the routes being developed, especially in China, consume much lower amounts of reagent and, therefore, can be applied effectively to these types of deposits.
NexantECA- Drivers behind the development of alternative lithium production
The novelty within the mineral extraction processes is predominantly focused on the front-end roasting and/or leaching of the mineral concentrate. Due to the lower amounts of lithium present in the unconventional deposits being targeted, leaching results in greater amounts of impurities in the leachate, resulting in more complex and costly downstream purification steps. The technological principles used in these technologies are not novel by nature, but their application to unconventional resources is new. The unconventional resources being targeted include:
Low grade lithium bearing clays. Bacanora is developing production at a deposit in Sonora, Mexico. The mineralization occurs primarily as polylithionite and hectorite.
Lithium aluminum silicates found as micas. Lepidolite is the most common of the micas and has a variable composition of lithium and gangue materials. Lepidico is developing the Karibib deposit in Namibia. Micas are typically characterized by their high content in other elements such as fluorine, rubidium, and cesium.
Low grade spodumene. As found at Medaro’s Superb Lake lithium and CYR South lithium properties.
Newly discovered minerals such as Jadarite. Jadarite is a lithium sodium borosilicate. The high contents of lithium (3.4 percent) and boron (14.7 percent) make it amenable to exploitation. Rio Tinto’s Jadar project aimed to produce battery-grade lithium carbonate in addition to borates.
Historically, extraction of lithium from brines has been limited in China with commercial operations mainly focused on hard rock lepidolite and spodumene deposits. The majority of China’s lithium reserves are found in salt-lake brines, typically with very high magnesium-to-lithium ratio, in remote locations and harsh natural conditions. To date, efficient separation of magnesium and lithium-ions in brines with high ratio of magnesium to lithium has been a challenge. Extraction technologies developed in China are mainly targeted to address this limitation to exploit the largest resource of lithium in the country. There is little to no development in the hard-rock sector within China as most resources under development are based on spodumene with lepidolite resources acting as a marginal supply to the Chinese market – given the availability of competitively priced lithium carbonate from Australia and South America.
NexantECA - unconventional lithium resources
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NexantECA has completed a study titled ‘Emerging Lithium Extraction Technologies’ that provides an overview of technological, economic and commercial aspects of emerging lithium extraction technologies as well as providing a strategic review of each technology in comparison to its peers. As part of this study, NexantECA analyzed 16 emerging brine technologies, seven emerging mineral extraction technologies, and 10 emerging technologies developed in China (one for minerals and the rest for brines).
The Authors...
Daniel Saxton, Market Analytics Manager
Ivan Zovich, Senior Analyst