Process of obtaining a concentrate of β-spodumene

Abstract

This invention relates to a process for obtaining β-spodumene concentrate (1c) comprising a set of steps for decrepitation (2100) of an α-spodumene concentrate (1a), including the steps of feeding microwave equipment (103) with an α-spodumene concentrate (1a); applying microwaves by means of the equipment to the spodumene concentrate (1a); and cooling the decrepitated spodumene concentrate (1b). The invention further preferably relates to a set of grinding steps (2200) that includes the steps of transferring the decrepitated concentrate (1b) to a mill (201); grinding the decrepitated concentrate (1b); and passing the decrepitated concentrate (1b) through a sieve (202).

Description

Descriptive Report of the Invention Patent for “PROCESS FOR CONCENTRATING SPODUMENIUM, PROCESS FOR OBTAINING A p-SPODUMENIUM CONCENTRATE, AND PROCESS FOR OBTAINING LITHIUM DERIVATIVES”.

[0001] The present invention provides a process for obtaining a-spodumene concentrate whose steps include microwave-assisted ore comminution.

[0002] The present invention also relates to a process for obtaining a p-spodumene concentrate, or a process for processing an a-spodumene concentrate to obtain a p-spodumene concentrate, the steps of which allow efficient decrepitation and grinding of the a-spodumene concentrate, increasing the selectivity of the p-spodumene and, consequently, greater efficiency in obtaining the p-spodumene concentrate.

[0003] The present invention also provides processes for obtaining lithium derivatives whose steps include microwave-assisted leaching. Description of the State of the Art

[0004] Lithium has established itself as a strategic metal of extreme importance in global industry, especially in the technological era we live in. Its growing demand has been driven primarily by its essential role in the manufacture of lithium-ion batteries, widely used in portable electronic devices, electric vehicles, and renewable energy storage systems. Furthermore, lithium plays a significant role in medical applications, metallurgy, glass, ceramics, and other industries, making it a strategic resource for various sectors.

[0005] The search for an economically sustainable lithium beneficiation route has become a priority for the community scientific and industrial sectors, given that known reserves of this resource are limited and concentrated in specific regions of the globe. Therefore, it is crucial to develop and improve efficient extraction and processing methods that can ensure a continuous supply of this essential metal, while also considering the principles of economic and environmental sustainability.

[0006] Understanding the geology and mineralogy of lithium deposits, as well as the most appropriate beneficiation processes, is essential to maximizing product yield and quality. Furthermore, developing technologies that enable the recovery of valuable byproducts from beneficiation waste, as well as reducing energy and water consumption during the production stages, are essential factors in the quest for a more sustainable lithium production chain.

[0007] The state of the art relating to the production of lithium intermediates made from lithium minerals, mainly pegmatite, involves, in summary, the following steps: (i) crushing, grinding and classification of the spodumene ore; (ii) dense media separation of the spodumene; and (iii) flotation to obtain a chemical-grade spodumene concentrate.

[0008] These first three steps (i), (ii), and (iii) are aimed at producing a spodumene concentrate. This concentrate obtained comprises mainly a-spodumene and other elements such as quartz, albite, biotite, among others, and is also called a-spodumene concentrate.

[0009] Spodumene exhibits a peculiar characteristic called anisotropic expansion, meaning it expands unevenly in different directions when heated. This differential expansion can generate internal stresses in the mineral, leading to its breakage or fracture—a process called decrepitation.

[0010] Furthermore, when spodumene is heated, it can transform into other minerals through a process called mineralogical alteration. For example, a-spodumene can transform into p-spodumene through a process called spodumenization. This new mineral has a larger volume than the original spodumene, which can also lead to internal stresses and, consequently, decrepitation. Therefore, steps to obtain o-spodumene are advantageous for greater mineral processing efficiency, and the development of process improvements to improve spodumene selectivity during the conversion of a-spodumene to p-spodumene is desirable.

[0011] Obtaining an O-spodumene concentrate depends on the decrepitation process mentioned above. In the case of spodumene, decrepitation occurs primarily as a result of thermal expansion and mineralogical alteration.

[0012] The following steps are used to obtain lithium carbonate from a-spodumene concentrate: (iv) conversion of a-spodumene to p-spodumene; (v) reaction with sulfuric acid; (vi) successive stages of solution purification; and (vii-a) production of battery-grade lithium hydroxide; or (vii-b) production of lithium carbonate.

[0013] These steps comprise the process for obtaining lithium carbonate from spodumene, enabling the mineral to be used as an essential raw material for the manufacture of lithium-ion batteries. However, potential for increasing process efficiency has been identified, both in terms of spodumene selectivity and in terms of reducing the generation of fine particles of lesser-interest elements during the spodumene concentrate production steps.

[0014] p-spodumene concentrate is a commodity It is sold in various concentrations relative to lithium content, with values ​​between 5 and 6% w / w Li2O being common in the international market. These lithium oxide concentrations imply a p-spodumene concentration in the ore of approximately 60% to 75%. That is, considering the case of 5.5% Li2O (quite typical in the market), commercial p-spodumene concentrate will contain approximately 70% spodumene, which implies the transportation of 30% of waste, increasing CO2 emissions per kg of lithium produced and lengthening the emissions chain. This means that the electrification of transportation, which is based on lithium-ion batteries, makes the transportation chain dirtier.

[0015] Furthermore, decrepitation can facilitate mineral leaching and increase the surface area available for chemical extraction, improving process efficiency. This decrepitation step is performed in a high-temperature rotary calciner (above 1000°C) or similar means, using equipment such as a hot gas generator (GGQ) fueled by oil, natural gas, or other fuels as the heat source for the transformation. This also necessitates finding alternative, more efficient means of heating or transferring energy during the decrepitation step to reduce the emission of gases harmful to the environment and increase process efficiency by performing decrepitation at lower temperatures. Objectives of the Invention

[0016] A first objective of the present invention is to provide a process for obtaining p-spodumene concentrate that is capable of allowing greater selectivity of the spodumene from the treated ore.

[0017] A second objective of the present invention is to provide a process for obtaining p-spodumene concentrate that is capable of reducing the amount of fine particles of lower-grade elements. interest generated during the production of the concentrate.

[0018] A third objective of the present invention is to provide a process for obtaining p-spodumene concentrate that eliminates the need to use oil or natural gas, among other fuels that are harmful to the environment, and that is capable of processing spodumene at lower temperatures without the use of an indirect rotary calciner or hot gas generator.

[0019] A fourth object of the present invention is to provide a spodumene concentration process that includes a microwave-assisted comminution step.

[0020] A fifth objective of the present invention is a process for obtaining lithium derivatives that includes a microwave-assisted leaching step. Brief Description of the Invention

[0021] The present invention relates to a process for obtaining p-spodumene concentrate comprising a set of steps for decrepitating an a-spodumene concentrate, including the steps of feeding a microwave equipment with an a-spodumene concentrate; incident, through the microwave equipment and on the spodumene concentrate, microwaves with energy between 50 and 1000 kW.h per ton of spodumene concentrate, preferably between 100 and 500 kW.h per ton of spodumene concentrate, more preferably between 250 and 350 kW.h per ton of spodumene concentrate, to obtain a decrepitated spodumene concentrate; and cooling the decrepitated spodumene concentrate.

[0022] In one embodiment, the process comprises the step of verifying whether 90% m / m of the decrepitated spodumene concentrate has a particle size between 1 m and 300 pm, preferably between 100 pm and 200 pm, more preferably between 125 pm and 175 pm and, if not, perform a set of grinding steps, the set of grinding steps including the steps of transferring the decrepitated concentrate to a mill; grinding the decrepitated concentrate for at least 15 minutes, preferably for at least 1 hour, more preferably for at least 2 hours; passing the decrepitated concentrate through a sieve with a mesh size between 1.41 mm and 6.35 mm, preferably with a mesh size equal to 3.36 mm, to obtain a coarse portion of decrepitated spodumene concentrate containing above 80% concentration of elements other than p-spodumene, preferably above 90%, more preferably above 93%, and to obtain a fine portion of p-spodumene concentrate.

[0023] In one embodiment, the process comprises a set of size classification steps that includes a size classification step through a first preheated air classifier; a size classification step through a second air classifier; and a size classification step through a bag filter.

[0024] In one embodiment, the cooling step is carried out in a rotary cooler and the extracted heat is reused to preheat the first aeroclassifier.

[0025] In one embodiment, the decrepitated spodumene passes through a third aeroclassifier before proceeding to the set of grinding stages.

[0026] In one embodiment, the mill is an autogenous or semi-autogenous mill.

[0027] In one embodiment, the decrepitated beta spodumene is ground and passed through a set of sieves to obtain the fine beta spodumene concentrate.

[0028] The present invention also contemplates a process for concentrating spodumene that comprises a comminution step microwave-assisted.

[0029] In one embodiment, the microwave-assisted comminution step occurs between 5 and 60 minutes, at a microwave power of 0.5kW to 100kW.

[0030] The present invention also contemplates a process for obtaining lithium derivatives from a spodumene concentrate that comprises a microwave-assisted basic leaching step.

[0031] In one embodiment, the microwave-assisted basic leaching step is performed for between 10 and 20 minutes. Brief Description of the Drawings

[0032] The present invention will now be described in more detail based on an example of execution represented in the drawings. The figures show:

[0033] Figure 1 - is a photo of an exemplary sample of spodumene concentrate;

[0034] Figure 2 - is an X-ray diffractogram of the exemplary sample of spodumene concentrate;

[0035] Figure 3 - is a schematic representation of the set of decrepitation steps of the process of the present invention in a preferred embodiment;

[0036] Figure 4 - is a photo of the exemplary sample of decrepitated spodumene concentrate;

[0037] Figure 5 - is an illustration of the set of grinding steps of the process of the present invention in a preferred embodiment;

[0038] Figure 6 - is a photo of an exemplary sample of the p-spodumene concentrate obtained after grinding;

[0039] Figure 7 - is an X-ray diffractogram of the exemplary sample of the p-spodumene concentrate obtained after grinding;

[0040] Figure 8 - is a graph of the amount of accumulated retentate (%) of different samples as a function of the mesh of a sieve after autogenous grinding;

[0041] Figure 9 - is a graph of the amount of accumulated retentate (%) of different samples as a function of the mesh size of a sieve after semi-autogenous grinding;

[0042] Figure 10 - is a photo of a sample of low-grade a-spodumene concentrate;

[0043] Figure 11 - is an X-ray diffractogram of the low-grade a-spodumene concentrate sample;

[0044] Figure 12 - is a photo of a sample of p-spodumene concentrate obtained from low-grade a-spodumene concentrate;

[0045] Figure 13 - is an X-ray diffractogram of the sample of p-spodumene concentrate obtained from the low-grade a-spodumene concentrate;

[0046] Figure 14 - is a schematic representation of processes for obtaining a spodumene concentrate and obtaining lithium derivatives from a state-of-the-art spodumene concentrate;

[0047] Figure 15 - is a schematic representation of the process of obtaining a spodumene concentrate of the present invention in a preferred embodiment;

[0048] Figure 16 - is a schematic representation of the process of obtaining lithium derivatives of the present invention in a preferred embodiment; and

[0049] Figure 17 - is a schematic representation of the process of obtaining lithium derivatives of the present invention in a second preferred embodiment; Detailed Description of Figures

[0050] First, it should be noted that the term “preferential” here used to characterize a particularly efficient embodiment of the invention among the many possible ones. The term “preferred” should not be understood as limiting the possible embodiments of the present invention, that is, it should not be understood as “imperative” or “mandatory” for carrying out the present invention.

[0051] Figure 1 shows a photograph of an exemplary sample of a-spodumene concentrate 1a, showing a typical fragment size distribution, and Figure 2 presents an X-ray diffractogram of the sample. X-ray diffractometry analysis of Figure 2 reveals that the composition of the exemplary sample of a-spodumene concentrate 1a identified here is 63.9% a-spodumene, in addition to other elements that include quartz (19.9%), albite (10.1%), biotite (3.3%), microline (2.1%), and muscovite (0.7%). The process of the present invention seeks to transform the largest possible amount of a-spodumene contained in the a-spodumene concentrate 1a into p-spodumene, in an efficient manner, to obtain a p-spodumene concentrate, while keeping out of the p-spodumene concentrate the other elements of lesser interest contained in the a-spodumene concentrate 1a.It will be understood that the sample presented here is merely an example of a type of a-spodumene concentrate, and that other concentrates with other proportions of elements may be equally benefited through the process proposed here, as will be demonstrated later.

[0052] Figure 3 illustrates the microwave-assisted decrepitation step set 2100 of the present invention in a preferred embodiment. Preferably, the α-spodumene concentrate 1a initially passes through a size classification step set 110 that includes a size classification step in a first aeroclassifier 102 with preheating, this preheating consuming 5 to 50% of all the energy used in the process. decrepitation 2100, more preferably from 10 to 25% and most preferably between 15 and 20%. Preferably, the preheating energy in the first aeroclassifier 102 is obtained from the sensible heat of the decrepitated spodumene concentrate 1 b derived from the cooler 104, which heat is directed to the first aeroclassifier 102 and reused, as will be further detailed below. The set of size classification steps 110 also comprises a second aeroclassifier 111 that receives the material retained by the first aeroclassifier 102 and the material retained by a third aeroclassifier 105 arranged after the cooler 104, to be reprocessed and sent again to the first aeroclassifier 102, and a bag filter 112 that receives the material retained by the second aeroclassifier 111, to be reprocessed and sent to microwave equipment 103 as will be detailed below.As will be understood, the purpose of the size classification steps is to increase the capture of decrepitated spodumene, which becomes fine and light after the decrepitation and milling steps. Size classification aims to ensure, ideally, the maximum possible quantity of product.

[0053] The α-spodumene concentrate 1a, preferably preheated, is fed into microwave equipment 103, where it will receive microwaves with energy ranging from 50 to 1000 kW.h per ton of concentrate, preferably between 100 and 500 kW.h per ton of concentrate, more preferably between 250 and 350 kW.h per ton of concentrate, with a microwave frequency between 300 MHz and 300 GHz, preferably between 915 MHz and 2450 MHz. The energy is preferably supplied by a suitable, low-carbon electricity source. This energy will be used in the decrepitation process, with an efficiency of between 80 and 100% conversion of α-spodumene to β-spodumene. preferably between 85 and 99%, more preferably above 95%. Preferably, the microwave incidence time should be sufficient to perform a conversion of a-spodumene to p-spodumene between 80 and 100%, preferably between 85 and 99%, and most preferably above 95%.

[0054] The material then proceeds to the cooling step, which should preferably take place in indirect cooling equipment, such as an indirect rotary cooler 104, in order to avoid lithium loss in the fines and reuse the sensible heat of the decrepitated spodumene 1 b to preheat the a-spodumene concentrate 1 a. Cooling is preferably carried out until the material reaches the standard working temperature of the equipment of the subsequent unit operation or the lowest standard temperature among the subsequent equipment (e.g., air classifier and / or grinder). At the end of the set of decrepitation steps 2100, part of the cooled decrepitated spodumene 1 b may pass through a third air classifier 105 to capture any spodumene dust that may escape through the gas capture and treatment systems, before proceeding to the set of grinding steps 2200.

[0055] As a result of the set of decrepitation steps 2100, the decrepitated spodumene concentrate 1 b is obtained, seen in a typical photo in Figure 4, where the size distribution of the fragments is seen before passing through the set of grinding steps 2200. At this step, an evaluation of the particle size can be made and, if it is found to have low particle size, for example, between 1 m and 300 pm, more preferably between 100 pm and 200 pm, more preferably between 125 pm and 175 pm, with a p-spodumene content (1c) preferably above 85%, they do not need to go through the set of grinding steps 2200, and this decrepitated spodumene concentrate 1 b can be considered a p- spodumene 1c. The greater selectivity of the microwave-assisted decrepitation process 2100 allows for great efficiency in the subsequent grinding process 2200.

[0056] Figure 5 illustrates the set of grinding steps 2200, which is performed if the particle size of the decrepitated spodumene concentrate 1 b is not yet suitable to be considered a p-spodumene concentrate. The cooled decrepitated spodumene concentrate 1 b is transferred to an autogenous or semi-autogenous mill 201 and processed until a grinding is achieved with, preferably, a concentration above 90% of p-spodumene in a particle size between 3.36 mm and 1 pm, preferably between 0.5 mm and 5 pm, more preferably between 150 pm and 10 pm. It should be noted that the use of microwaves for decrepitation allows for greater selectivity of spodumene during the process, which allows for the efficient use of autogenous or semi-autogenous grinding, in contrast to the state of the art whose decrepitation by known means has low selectivity and makes the use of autogenous or semi-autogenous grinding inefficient.

[0057] The autogenous or semi-autogenous grinding process 201 reduces the particle size of decrepitated spodumene 1b, generating a fine portion that is the p-spodumene concentrate 1c, and a coarse portion 3 that contains mostly elements of lesser interest. The separation of the p-spodumene concentrate 1c is preferably done on sieves 202 or an air classifier, so that the coarse portion 3 contains more than 80% concentration of elements other than p-spodumene, that is, elements of lesser interest to the spodumene rock, such as quartz, albite, muscovite, mica, among others, more preferably above 90%, and most preferably above 93%.

[0058] The p-spodumene concentrate 1c, seen in Figure 6, should have a lithium oxide content between 6 and 8% m / m, preferably between 7 and 7.9% m / m, more preferably between 7.7% and 7.8%, of lithium oxide concentration in the concentrate, in the fine fraction between 70 and 100% m / m, preferably between 90 and 99%, more preferably between 95 and 98%, in addition to a very low content of low added value by-products in the concentrate. Such composition favors transportation and reveals the energy optimization of the conversion of a-spodumene to p-spodumene proposed by the present invention, as well as the reduction of damage to the environment, given that the heating / decrepitation operation of the prior art uses an indirect rotary kiln (gas-fired) to perform the same conversion.

[0059] Figure 7 illustrates the X-ray diffractometry analysis of the p-spodumene concentrate 1c produced by the present invention and a reference. It is noteworthy that the peak with a concentration of 0.6% is related to a-spodumene and peaks "II" and "III" are related to the anisotropic expansion promoted by the heating or microwave energy transfer step of the present invention, that is, p-spodumene.

[0060] Figures 8 and 9 illustrate the amount of decrepitated concentrate 1b retained and the amount of p-spodumene concentrate 1c retained before the grinding process and after the grinding process for 15 minutes, 1 hour and 2 hours, as a function of the mesh size of sieve 202. Figure 8 illustrates the result for the autogenous grinding process and Figure 9 illustrates the semi-autogenous grinding process.

[0061] Tables 1 and 2 below show the distributions of spodumene and lithium oxide present after two hours of autogenous and semi-autogenous milling. Table 1 - Distribution of autogenous grinding: Distribution of autogenous grinding Table 2 - Distribution of semi-autogenous grinding:

[0062] With the present process of obtaining p-spodumene concentrate 1c, there is a conversion of a-spodumene to p-spodumene above 99% with a final concentration of p-spodumene above 98%, that is, the present invention allows the generation of a fine and decrepitated concentrate with greater efficiency, less energy use and the possibility of using alternative energy sources, totally different from that produced in the state of the art.

[0063] In addition, the p-spodumene concentrate of the present invention is capable of processing materials with low spodumene content. efficiently. Figure 10 shows a typical photograph of low-grade α-spodumene concentrate, showing the fragment size distribution. α-spodumene makes up only 29.9% of this material, as can be seen in the X-ray diffractogram in Figure 11. This type of low-grade α-spodumene concentrate is usually considered a low-value-added byproduct by the lithium industry, given that the low α-spodumene content makes it impossible to recover β-spodumene using conventional prior-art processes, and it is generally discarded. However, the process of the present invention is capable of efficiently recovering β-spodumene from low-grade α-spodumene concentrates such as the one mentioned above, enabling the processing of this type of material.

[0064] After beneficiation of this α-spodumene-poor concentrate by the process of the present invention, the p-spodumene concentrate seen in Figure 12 in a typical photo is obtained, whose composition is seen in the X-ray diffractometry analysis revealed in Figure 13. In this case, there is a 90% efficiency in the conversion of α-spodumene to p-spodumene and an increase in spodumene content from 29.9% to 89.4%. Therefore, the process of the present invention is capable of transforming the low-grade α-spodumene concentrate, previously considered a low-value-added byproduct by the state of the art, into a material with high spodumene contents in an efficient, commercially viable, and environmentally friendly manner. Furthermore, the decrepitation process of a-spodumene occurs at lower temperatures (between 700°C and 800°C) compared to the processes usually applied in the state of the art, where temperatures above 1000°C are seen.

[0065] In accordance with the process for obtaining a p-spodumene concentrate proposed above, the present invention also proposes a process for concentrating a-spodumene and a lithium ore recovery process, as follows.

[0066] For a better understanding of the invention, Figure 14 illustrates a spodumene concentration process 1000' combined with a process for obtaining lithium derivatives 2000' from a spodumene concentrate, as currently known in the state of the art.

[0067] The prior art spodumene concentration process 1000' begins with the receipt of raw ore M0' and the mechanical processing step 1001', which may involve, for example, crushing, grinding, and classifying the processed ore. Subsequently, the mechanically processed ore MT undergoes a dense media separation step 1002', combined or not with magnetic separation, which may involve, for example, the use of dense media to separate the spodumene from other minerals and impurities. It is clarified that spodumene has a density of 3.2 g / cm 3 while quartz, feldspar and muscovite have densities in the range of 2.6 g / cm 3 (densities measured, for example, according to the ASTMD854 standard). Thus, using a dense liquid, such as bromoform, in a laboratory, and / or a mixture of magnetite and water, industrially, the spodumene is sunk while the other gangue minerals are floated.

[0068] The spodumene separated E0' in the previous step then passes to a flotation step 1003' for further concentration, seeking a chemical grade concentrate with a lithium superoxide (LiO2) content between 6% and 7% mass / mass (m / m), thus obtaining an a-spodumene concentrate CEa'.

[0069] After obtaining the spodumene concentrate CE', said concentrate CE' passes to the process of obtaining lithium derivatives 2000', according to the following steps.

[0070] The a-spodumene concentrate CEa' is aimed at a first stage of conversion of spodumene 2100', where the concentrate is heated to approximately 1050°C to convert its crystalline structure to p-spodumene, obtaining a p-spodumene concentrate CEp1'. The objective of this stage, according to the state of the art, is to make the product more reactive with the sulfuric acid used in the next stage.

[0071] The p-spodumene concentrate CEp1' is then directed to the reaction step with sulfuric acid 2300' to produce lithium sulfate and aluminum silicates, obtaining a p-spodumene concentrate CEp2' containing these components.

[0072] This p-spodumene concentrate CEp2' then goes through a washing step 2400' to dissolve the lithium sulfate and separate it from the aluminum silicate and other components considered as impurities in this prior art process, obtaining a p-spodumene concentrate CEp3' without these components.

[0073] The p-spodumene concentrate CEp3' then goes through successive purification stages 2500' of the solution to remove other elements considered as impurities in the state of the art process, such as iron and aluminum, obtaining a p-spodumene concentrate CEp4' without these elements.

[0074] From here the p-spodumene concentrate CEp4' can proceed to an electromembrane electrolysis step 2600A' to obtain lithium hydroxide (LiOH), or to a precipitation step 2500B' with the addition of sodium carbonate to obtain lithium carbonate (LÍ2CO3).

[0075] Figure 15 illustrates a representation of the spodumene concentration process 1000 of the present invention in a preferred embodiment. Unlike the prior art, the raw ore M0 is directed to a microwave-assisted comminution step 1001, rather than mechanical comminution or processing. conventional.

[0076] It was observed that the use of microwaves during comminution results in the release of spodumene, generating a coarser lithium-rich material. This provides significant industrial benefits to the concentration process, as the lithium separation and concentration processes (to be performed later) are more efficient for materials with larger grain sizes.

[0077] More specifically, the use of microwaves in the comminution process exploits the variable interaction of the minerals contained in the pegmatite with the microwaves, which results in an increase in selectivity during the comminution process and consequently in the efficiency of spodumene recovery.

[0078] Pegmatites, igneous rocks with an abundance of quartz, feldspar, and mica crystals, in particular, contain minerals that respond differently to microwave exposure. This variation in response is related to the electrical conductivity, permittivity, and magnetic susceptibility of each mineral. When exposed to microwaves, these minerals heat unevenly and vibrate at different rates, leading to the formation of internal stresses that can result in fractures at the interface between the minerals.

[0079] Surprisingly, it was observed that, due to the difference in loss tangents, this selective fracturing facilitated by microwaves increases selectivity in comminution, as it favors the breakage of the ore at the boundaries between different minerals, rather than the more random and less selective breakage observed in conventional comminution methods. This results in greater release of spodumene, facilitating its isolation and, therefore, improving its recovery.

[0080] Furthermore, the microwave-assisted comminution step 1001 as proposed herein reduces the generation of ultrafine particles, commonly produced in conventional processes due to the high mechanical energy involved. In microwave-assisted comminution, part of the energy used for comminution comes from the microwaves themselves, reducing the need for impact and, consequently, the production of fines. This improves process efficiency, minimizing ore waste and reducing environmental impact.

[0081] Preferably, the microwave-assisted comminution step 1001 occurs between 5 and 60 minutes, at a microwave power of 0.5kW to 100kW, using susceptor materials among fuels (such as biomass and charcoal), silicon carbide, among others. After the microwave-assisted comminution step 1001, the processed ore M1 m preferably undergoes a dense medium separation step 1002 to obtain separated spodumene E0m and subsequently, if necessary, a flotation step 1003, seeking a chemical grade concentrate with a lithium superoxide (LiO2) content between 6% and 7% w / w, thus obtaining an α-spodumene concentrate CEam.

[0082] Figure 16 shows the process for obtaining lithium derivatives 2000 of the present invention in a first embodiment where the spodumene conversion step 2100' seen in the prior art is replaced by a microwave-assisted decryption step 2100 and a milling step 2200 to obtain a p-spodumene concentrate CEApI m. The steps or sets of steps of microwave-assisted decryption 2100 and milling 2200 may be, for example, those proposed by the present invention. The microwave-assisted decryption step 2100 may be used to replace the heat source used by the prior art and transform the α-spodumene into a reactive form of β-spodumene. The fact that the microwave can use renewable energy sources brings economic and environmental advantages to the process. Furthermore, in addition to microwave power supply, some susceptor material can be used in conjunction, which absorbs electromagnetic waves more efficiently, and which can facilitate this phase transformation.

[0083] The p-spodumene concentrate CEApI m is directed to the reaction step with sulfuric acid 2300 to produce lithium sulfate and aluminum silicates, obtaining a p-spodumene concentrate CEAp2m containing these components.

[0084] This p-spodumene concentrate CEAp2m then goes through a washing step 2400 to dissolve the lithium sulfate and separate it from the aluminum silicate and other components considered as impurities in this prior art process, obtaining a p-spodumene concentrate CEAp3m without these components.

[0085] The p-spodumene concentrate CEAp3m then goes through successive stages of purification 2500 of the solution to remove other elements considered as impurities in the state of the art process, such as iron and aluminum, obtaining a p-spodumene concentrate CEAp4m without these elements.

[0086] From here the p-spodumene concentrate CEAp4m can proceed to an electromembrane electrolysis step 2600A to obtain lithium hydroxide (LiOH), or to a precipitation step 2600B with the addition of sodium carbonate to obtain lithium carbonate (LÍ2CO3).

[0087] Figure 17 reveals a process for obtaining lithium derivatives 3000 of the present invention in a second embodiment, where the steps of conversion of spodumene 2100' and reaction with sulfuric acid 2300' seen in the prior art are replaced by a single microwave-assisted basic leaching step 3100 to obtain a soluble form of lithium FSL1, such as, for example, lithium hydroxide.

[0088] More specifically, through the use of microwaves to By assisting the leaching step, the decryption step to make the lithium soluble will not be necessary, so this embodiment eliminates at least two unit operations and allows for more efficient and less costly beneficiation. Furthermore, the microwave can be powered by renewable energy sources, and the lack of fuel in decryption will reduce greenhouse gas (GHG) emissions from the prior art process.

[0089] Tests using acid leaching for this process embodiment did not yield satisfactory results. A combination of a basic leaching step using preferably sodium hydroxide (NaOH) followed by a leaching step with 3200 mol / L water to obtain a solubilized form of lithium FLS2 yielded significant lithium recovery results.

[0090] It was observed that increasing the amount of NaOH used also increased lithium recovery, while the optimal microwave exposure time of the spodumene concentrate ranged from 10 to 20 minutes, with longer or shorter exposure times tending to decrease recovery efficiency. It was also observed that the absence of microwave exposure resulted in insignificant recovery, demonstrating that the use of microwave-assisted basic leaching had an unexpectedly positive effect on recovery.

[0091] Other steps in this lithium carbonate production process 3000 can be performed in a manner similar to the prior art. For clarity, the other steps in this process 3000 are described below.

[0092] The solubilized form of lithium FLS2 obtained after the water leaching step 3200 is directed to the washing step 3300 for dissolving the lithium hydroxide and separating it from the aluminum silicate and other components considered as impurities in this process. state of the art, obtaining a liquid concentrate of lithium hydroxide CHL1 without these components.

[0093] The concentrate in the form of lithium hydroxide CHL1 then goes through successive stages of purification 3400 of the solution to remove other elements considered as impurities in the prior art process, such as iron and aluminum, obtaining a lithium hydroxide concentrate CHL2 without these elements.

[0094] From here the lithium hydroxide concentrate CHL2 can proceed to an electromembrane electrolysis step 3500A to obtain purified lithium hydroxide (LiOH), or to a precipitation step 3500B with the addition of sodium carbonate to obtain lithium carbonate (LÍ2CO3).

[0095] It will be understood that the spodumene concentration process 1000 proposed herein may optionally be combined with the first 2000 or second 3000 embodiments of the lithium derivatives recovery process proposed herein, their combination not being mandatory, but resulting in greater efficiency to the processes as a whole.

[0096] Having described a preferred embodiment, it should be understood that the scope of the present invention encompasses other possible variations, being limited only by the content of the appended claims, including possible equivalents.

Claims

CLAIMS 1. Process for obtaining p-spodumene concentrate (1c) characterized by the fact that it comprises a set of steps for decrepitation (2100) of an a-spodumene concentrate (1a), including the steps of: - Feed a microwave equipment (103) with an a-spodumene concentrate (1a); - Apply, through the microwave equipment and on the spodumene concentrate (1 a), microwaves with energy between 50 and 1000 kW.h per ton of spodumene concentrate (1a), preferably between 100 and 500 kW.h per ton of spodumene concentrate (1a), more preferably between 250 and 350 kW.h per ton of spodumene concentrate (1a), to obtain a decrepitated spodumene concentrate (1 b); and - Cool the decrepitated spodumene concentrate (1 b).

2. Process for obtaining p-spodumene concentrate (1c), according to claim 1, characterized by the fact that it comprises the step of verifying whether 90% m / m of the decrepitated spodumene concentrate (1b) has a particle size between 1 m and 300 pm, preferably between 100 pm and 200 pm, more preferably between 125 pm and 175 pm and, if negative, carrying out a set of grinding steps (2200), the set of grinding steps (2200) including the steps of: - Transfer the decrepitated concentrate (1 b) to a mill (201); - Grind the decrepitated concentrate (1 b) for at least 15 minutes, preferably for at least 1 hour, more preferably for at least 2 hours; - Pass the decrepitated concentrate (1 b) through a sieve (202) with mesh between 1.41 mm and 6.35 mm, preferably with mesh equal to 3.36 mm, to obtain a thick portion of decrepitated spodumene concentrate (1 b) containing above 80% concentration of elements other than p-spodumene, preferably above 90%, more preferably above 93%, and to obtain a fine portion of p-spodumene concentrate (1c).

3. Process for obtaining p-spodumene concentrate (1c), according to claim 1, characterized by the fact that it comprises a set of size classification steps (110) that includes: - a size classification step using a first preheated air classifier (102); - a size classification step by means of a second aeroclassifier (11 1); and - a size classification step through a bag filter (112).

4. Process for obtaining p-spodumene concentrate (1c), according to claim 3, characterized by the fact that the cooling step is carried out in a rotary cooler (104) and the extracted heat is reused for preheating the first aeroclassifier (102).

5. Process for obtaining p-spodumene concentrate (1c), according to any one of claims 2 to 4, characterized by the fact that the decrepitated spodumene (1 b) passes through a third aeroclassifier (105) before proceeding to the set of grinding stages (2200).

6. Process for obtaining p-spodumene concentrate (1c), according to claim 2, characterized by the fact that the mill (201) is an autogenous or semi-autogenous mill.

7. Process (1000) for concentrating spodumene characterized by the fact that it comprises a microwave-assisted comminution step (1001).

8. Process (1000) for concentrating spodumene, according to claim 7, characterized by the fact that the microwave-assisted comminution step (1001) occurs between 5 and 60 minutes, at a microwave power of 0.5kW to 100kW.

9. Process (3000) for obtaining lithium derivatives from a spodumene concentrate characterized by the fact that it comprises a microwave-assisted basic leaching step (3100).

10. Process (3000) for obtaining lithium derivatives, according to claim 9, characterized by the fact that the microwave-assisted basic leaching step (3100) is carried out for between 10 and 20 minutes.

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