A research team from the Massachusetts Institute of Technology (MIT) in the United States recently announced a new process that is expected to significantly reduce the energy consumption and cost of extracting lithium from hard rock. It is believed that it may change the economic ledger of electric vehicle batteries. Relevant research, published in the journal Science, focuses on how to reduce energy consumption and waste emissions when processing lithium-containing hard rock ores.
At present, a key reason why lithium-ion batteries dominate the battery market is that its supply chain is large-scale and its system is mature, forming a highly efficient global lithium supply network, making it difficult for alternative technologies to compete on cost. However, this advantage is highly dependent on the stable supply of cheap lithium resources, and current lower-cost lithium resources mainly come from salt lake brine deposits concentrated in South America. Although lithium is not scarce in terms of abundance in the earth's crust, high-quality ore sources that are easy to mine and low-cost are not abundant.
Against this background, people continue to focus on a lithium-containing mineral called spodumene, which is the world's most abundant hard rock lithium resource. However, traditional spodumene processing technology is expensive: the ore needs to be heated to about 1,000 degrees Celsius and then leached with sulfuric acid to extract lithium. Although this process is mature and reliable, it is accompanied by huge energy consumption and produces a large amount of sulfur-containing waste.
The new approach proposed by MIT and its collaborators takes a very different path. Instead of starting with high-temperature roasting, the process uses an ammonium fluoride solution heated to about 70 degrees Celsius to break down the mineral structure. In this process, the ore is separated into three material streams: lithium, silicon and aluminum: lithium is dissolved in the solution in the form of lithium fluoride, silicon forms a soluble compound, and aluminum is converted into a solid intermediate product for easy processing.
In subsequent steps, the treatment of aluminum is the most energy-intensive link in the process, requiring staged heating, first to about 300 degrees Celsius, and then to about 700 degrees Celsius, to ultimately produce alumina with a purity of more than 98%. In comparison, the treatment of silicon is relatively simple: by adding ammonia, the silicon compounds in the solution are converted into silica precipitates, which are easy to separate. The research team noted that these silicas could be used as concrete additives, potentially helping to partially offset processing costs.
Lithium always remains in solution as lithium fluoride. In this form, it can be directly used as a precursor for the electrolyte material lithium hexafluorophosphate, or it can be further converted into lithium nitrate and then prepared into lithium oxide to enter the traditional battery material production process. This provides multiple path options for connecting the new process with the existing lithium battery industry chain.
A major feature of the new process is the "closed-loop" management of its own reaction system. During the multi-step reaction process, substances such as ammonia and hydrogen fluoride will be generated; instead of treating them as waste, the research team designed a recycling link to resynthesize the two into ammonium fluoride to participate in front-end processing again. This closed-loop design helps reduce reagent losses and waste emissions, but it also means strict safety management of highly corrosive and toxic hydrogen fluoride is required.
From an economic point of view, calculations given by the research team show that the cost of traditional spodumene processing is slightly less than US$9,000 per ton of lithium, while the new process is expected to reduce the cost to more than US$5,000 per ton, which is roughly close to the cost level of lithium extraction from high-quality brine resources. If aluminum and silicon by-products can successfully enter the market and be monetized, there is room for further reduction in overall costs.
However, the researchers also emphasized that there are still multiple uncertainties between laboratory measurements and actual factory operations. Actual costs will depend on factors such as ore grade, market price fluctuations, and the capital investment required to build or modify production facilities for the new process. Despite this, this work is still regarded as a new idea on the issue of lithium supply. It not only focuses on the geographical sources of lithium resources, but also attempts to optimize energy utilization and resource recovery models starting from the extraction process itself.