Patent Application
20240174527
The use of lithium in its multiple chemical formulations has gained traction in the technological world in general over the last years. Among those formulations is lithium hydroxide, which is mainly used in the production of lubricating greases capable of operating under extreme temperature and load conditions. Approximately 70% of the lubricating greases produced in the world contain lithium. Lithium hydroxide is also used in batteries and dyes.
According to the 2017 publication of the Chilean Copper Commission “INTERNATIONAL LITHIUM MARKET AND ITS POTENTIAL IN CHILE”, lithium is a metal whose properties are currently highly valued, including its high levels of electrical conductivity, low viscosity, in addition to its being very light and having a low thermal expansion coefficient. As a result of these qualities, lithium has multiple applications in the industrial sector and specifically in the field of batteries, given the current technological trend.
Electromobility, driven by environmental campaigns and regulations to reduce the use of fossil fuels, coupled with the technological development of electronic devices and energy storage systems, are all factors that are putting upward pressure on future lithium demand. The substantial projected growth for electric cars, using rechargeable batteries as a source of energy, has driven the projected demand for lithium, due to the higher charge density of lithium-ion batteries, in addition to the substantial price reductions experienced by these batteries.
When taken from brine sources, lithium is usually extracted by pumping the brine to the surface for concentration in evaporation ponds, by means of a series of solar ponds (conventional method), ultimately producing a concentrated lithium chloride (LiCl) solution. This lithium-rich solution is then processed to produce lithium carbonate and then lithium hydroxide.
In terms of products, the main lithium compounds that are marketed and produced are lithium carbonate (Li2CO3), lithium hydroxide monohydrate (LiOH·H2O), and lithium chloride (LiCl), with carbonate accounting for the largest output.
One of the advantages of lithium operations in salt flats is that the cost of pumping the brine, concentrating it in evaporation ponds, and then processing the solution in a plant to obtain lithium carbonate or hydroxide, is lower than mining it from ore. The latter type of mining involves processes similar to rock mining involving drilling, blasting, ore concentration and transportation.
Currently, Lithium hydroxide (LiOH) is produced from Lithium Carbonate or Lithium Sulfate, and there are no commercial manufacturing alternatives from lithium chloride (LiCl).
In general, in terms of the prior art, the systems or plants described above are those used for the production of lithium carbonate, which is subsequently used to obtain LiOH. Therefore, it is not possible to find a process that produces LiOH from LiCl without producing Lithium Carbonate. Thus, for example, Patent Publication U.S. Ser. No. 10/648,090 describes an integrated system for generating a lithium salt from a liquid resource, which consists of the following:
Additionally, publication RU2016103702 describes a Plant for obtaining high-purity lithium hydroxide monohydrate from natural brines containing lithium, comprising a device for obtaining primary lithium concentrate, connected by piping and fittings with the natural source of brine, a mother brine receiver, a vessel for collecting primary lithium concentrate, and a fresh water source; an electrolysis unit containing a membrane electrolyzer with a power supply; catholyte and anolyte tanks; catholyte and anolyte circulation pumps; gas separators for cathodic hydrogen and anodic chlorine; an evaporation unit to evaporate the lithium hydroxide solution and separate LiOH·H2O crystals, including an evaporator, a crystallizer, a condenser for condensate vapor, a centrifuge to separate LiOH·H2O crystals from the mother brine sources, a pump to supply catholyte for evaporation; an evaporator to concentrate a lithium chloride solution purified from impurities, a vessel to collect a stripped lithium chloride solution with a pump to transport it, an absorber to utilize chlorine from the anode by absorption with an aqueous solution containing urea, with a tank, a circulation pump and a ventilation unit, an absorber to harness excess anodic chlorine with a ventilation unit, a tank for collecting condensate, a source of heating steam, a source of cooling water, characterized in that the installation for implementing the method contains, in addition, a reverse osmosis concentrator-desalter, a reactor with a stirrer, for the purification of reagents from a reverse osmosis concentrate, a filter press for sediment separation and a vessel for the collection of purified reverse osmosis concentrate; an electrodialysis concentrator for concentrating the reverse osmosis concentrate purified from impurities, two ion exchange columns for deep purification of the electrodialysis concentrate, a vessel with hydrochloric acid solution, a vessel with lithium hydroxide solution, an evaporator for deep evaporation of the electrodialysis concentrate, a refrigerated vessel with a stirrer for crystallization of precipitated NaCl salts from K and a filter for their separation, a mixer to prepare an anolyte filling solution for electrochemical conversion of chloride to lithium hydroxide; countercurrent screw washer for LiOH·H2O crystals; a vacuum dryer and a filling machine for lithium hydroxide monohydrate and an absorber for the absorption of sodium chloride.
Unlike the previously described systems of the prior art, the system of this invention does not carry out concentration processes such as electrodialysis, nor reverse osmosis, nor electrochemical processes, such as electrolysis for conversion of LiCl into LiOH. Therefore, it is possible to have a system that operates under completely different principles for the formation of LiOH and its conversion from LiCl, based on the concept of fractional crystallization.
In particular, the difference with the Russian patent is the conversion technology developed to transform LiCl into LiOH·H2O. In the present invention, conversion occurs by the chemical reaction of LiCl with NaOH, and separation from NaCl occurs by fractional crystallization. In document RU2016103702, they use an electrochemical method as conversion technology, where the process is carried out by applying energy to an electrochemical system using a membrane separating cations and anions.
The figures are merely illustrative and any extension of system components and auxillary equipment will be understood to be included within the scope of protection.
Each sub-system may include a purge for the benefit of the quality of the final product.
The system for the production of lithium hydroxide (LiOH) directly from lithium chloride (LiCl), without the need for intermediate production of lithium carbonate or the like, consists of two sub-systems, a high purity LiOH·H2O production sub-system and a NaCl production sub-system.
The system comprises a LiCl brine tank (1) and a tank of mother liquor from the NaCl sub-system (2), which are connected to the high purity LiOH production sub-system, which comprises a conversion equipment (3) from LiCl to crude LiOH·H2O. The conversion equipment (3) is a crystallizer equipment that generates a crude LiOH·H2O stream. The conversion equipment (3) is connected to a solid-liquid separation equipment (4) from which two streams are generated: a liquid solution (ML1) composed of mother liquor 1, which is fed from the solid-liquid separation equipment (4) to a tank (9) of mother liquor 1 at the inlet of the NaCl production sub-system; and a second stream composed of crude LiOH·H2O crystals which is fed from the same solid-liquid separation equipment (4) to a dilution tank (5). Equipment (4) can be, for example, a centrifuge equipment. This dilution tank (5) is connected to at least one crystallizing equipment (6) where high purity LiOH, H2O is produced. Similarly, tank (A) provides the necessary water for dissolving crude LiOH·H2O within tank (5). The LiOH·H2O crystallizing equipment is connected to a second solid-liquid separation equipment (7) which has two outputs from which two products are generated: one output with a solid stream of high purity LiOH·H2O crystals which is sent to a crystal drying unit (8); and another output with a liquid stream of pure LiOH liquor which can be recycled directly to crystallizer (6).
The NaCl production sub-system is made up of said receiving tank (9) of mother liquor 1 and a NaOH tank (16), and both tanks in turn are connected to a causticizing unit (10), which is connected to an evaporation or water withdrawal system from the fed solution, and NaCl crystallizing unit (17). From the latter two outputs are generated; one is NaCl liquor that is connected to the NaCl liquor tank (13), being this NaCl liquor the mother liquor 2 (ML2) that is fed to the ML2 tank; and the other output is a NaCl pulp that is connected to a third solid-liquid separation equipment (11) from where the separation of NaCl crystals that are stored in the NaCl crystals unit (12) takes place. The NaCl or ML2 (13) liquor tank is connected to the initial NaCl liquor tank (2), and, thus, both sub-systems—the high purity LiOH·H2O production system and the NaCl production system—are connected via the mother liquor 1 and mother liquor 2 circuits, creating a circular system that enables the production of high-purity LiOH·H2O directly from LiCl brines, without NaCl co-precipitation.
In the invention's preferred method of execution, the high purity LiOH·H2O production sub-system comprises at least two crystallization equipment for crude LiOH·H2O (21 and 22). The LiOH crystallization tanks can be arranged in series (as illustrated in
In another preferred method of the invention, the NaCl production sub-system comprises multiple evaporator systems and a crystallizer equipment, as illustrated in
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CL2021/050016 | 3/20/2021 | WO |
