Tesla patent application = Lithium extraction process from clay minerals



On July 8, Tesla filed for a patent for processes for extracting lithium from a clay mineral and its composite elements. Lithium has been at the forefront of many technological changes since the 1990s with the commercialization of lithium-ion batteries – this is the reason for the revolution in electric vehicles (EVs) and personal technological devices.

Lithium is essential to the clean energy transition for batteries that provide energy and store energy. It is the gateway that releases renewable energy in a constant and reliable manner. Demand for lithium has skyrocketed in recent years as automakers have turned to electric vehicles much more, especially since many countries including UK, Sweden, Netherlands, France, Norway and Canada have announced a phase-out of cars with combustion engines.

According to the World Bank, 5 times more lithium than what is currently mined will be needed to meet global climate goals by 2050.

The new Tesla patent application includes providing a clay mineral comprising lithium, mixing a cation source with the clay mineral, performing high energy grinding of the clay mineral, and performing leaching. liquid to obtain a lithium-rich leach solution.

The ever-present need for lithium

An EV can have 5,000 battery cells and may require 10 kg of lithium. One ton of lithium can help meet the demand for 90 electric cars. About 60,000 tonnes of lithium carbonate equivalent are needed to produce one million electric cars. Tesla CEO Elon Musk noted that 30 million electric cars are due to be produced by 2027, which would require 1.8 million tonnes of lithium carbonate equivalent.

Consider the battery in a Tesla Model S. Thousands of cylindrical cells – much like nested dolls – with components from around the world turn lithium and electrons into enough energy to propel the car hundreds of miles. , again and again, without tailpipe emissions.

Typically, a main pack contains multiple modules, each consisting of many smaller cells. Inside each cell, atoms of lithium move through an electrolyte between a graphite anode and a cathode sheet made of a metal oxide.

Obtaining lithium by conventional means has its own environmental impact, due to carbon emissions and degradation of water and land. Demand for lithium with a smaller environmental footprint appears to be gaining ground.

The details of the Tesla patent application

The patent, titled “Selective Extraction of Lithium from Clay Minerals,” argues that extracting lithium from ore using sodium chloride is a more environmentally friendly way to obtain the metal by compared to currently used techniques such as acid leaching. According to Tesla, this also allows for higher recoveries.

Clay minerals are made up of microscopic framework layers composed of Li, Na, K, Al, Si, Mg, Ca, Fe, O and / or OH, and interlayer spaces through which cations like Li, Na, K and Mg can be carried in water or other electrolytes. The position of the lithium atom in this mineral structure makes all the difference for its extraction – whether the lithium is in the framework layer or floating in the interlayer.

Lithium, in small amounts, is prevalent in clay minerals. It is often present in clays in the form of impurities, inclusions, in reticular cavities, absorbed on the surface, or by isomorphic substitution, the latter being the most common.

The introduction to the Tesla patent application provides an introduction to lithium, explaining that it is a strategic metal for the lithium-ion battery (LIB) and electric vehicle (EV) industry. The importance of economically extracting lithium from various lithium sources has been identified as necessary to reduce the cost of batteries and electric cars.

The paper states that while the main sources of lithium commonly used for mining are lithium brines – due to the low cost associated with extracting Li from these sources – the ever-increasing demand for LIB makes exploration of other sources of lithium is necessary. Tesla’s new patent application examines another method of extracting Li: extracting Li from clay minerals.

Here is what the proposed Tesla process would consist of to extract lithium from a clay mineral:

  • providing a clay mineral comprising lithium;
  • perform a high energy mill of the clay mineral;
  • mixing a source of cations with the clay mineral together with, before or after performing the high energy mill to form a mixture, wherein the source of cations comprises a cation and an anion; and,
  • contacting the ground clay material and the cation source mixture with a solvent to extract lithium from the ground clay material and form a lithium rich leach solution.

In this process, lithium is obtained by acid leaching, where clay minerals are mixed with an aqueous solution of common mineral acids, such as H2SO4 or HCl, and then heated under atmospheric pressure to leach the lithium from the clay minerals. Tesla claims that this acid leach method not only leaches lithium, but also leaches high concentrations of impurities, including Na, K, Fe, Al, Ca, and Mg.

Lithium is typically extracted from minerals found in igneous rocks made up of large rocks (spodumene) or in water with a high concentration of lithium carbonate. In the Tesla patent application, the clay material was described as comprising one or more additional minerals selected from the group consisting of spodumene, lepidolite, zinnwaldite, smectite, hectorite, muscovite and combinations . The clay mineral includes one or more additional elements selected from the group consisting of sodium, potassium, iron, aluminum, calcium, magnesium, silicon, chromium and combinations.

The Tesla patent application notes that a high loss of lithium due to the subsequent removal of impurity elements, in particular the removal of Al, can significantly reduce the overall efficiency of lithium extraction.

Final thoughts

Many different approaches are underway to increase the amount of lithium available for the tech industry.

Vulcan Energy Resources announced that its main site has significant reserves, with lithium concentrations of 181 milligrams per liter. It is currently carrying out a full feasibility study, with the aim of moving to full commercial production of lithium in 2023-24. “We have a resource large enough to meet a very large amount of demand in European markets here for many years to come,” Vulcan CEO Francis Wedin said at a conference. industry last October.

Standard Lithium’s approach has focused on using a modern technological approach to mine lithium not only faster, but also to produce a higher purity product and reduce the associated environmental footprint. Using Steve Jobs’ approach of working backwards towards technology development, the project drives the process. This principle was fundamental for their team in the development of their proprietary LiSTR DLE process (LiSTR stands for “lithium stirred tank reactor”).

Tesla’s patent application comes at a time of hesitation to deplete battery-ready lithium by 2025. And as electric cars begin to take to the roads, lithium resources are crucial for the transition to a zero emission world.

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