FI126509B - A process for preparing beta-spodumen from a raw material containing alpha-spodumen - Google Patents

Description

A process for the preparation of a beta-spodumene from a raw material containing alpha-spodumene

Field of the Invention

The present invention relates to a process for the production of beta-spodumene from an alpha-spodumene-containing raw material, in particular material containing alpha-spodumene granules, according to the preamble of claim 1. In such a process, the material containing the alpha-spodumene granules is heated at a temperature of at least 800 ° C to convert the alpha-spodumene to the beta-spodumene.

Background

Lithium salts such as lithium carbonate and lithium ferrophosphate are increasingly used in the manufacture of batteries. Lithium is obtained from natural saline solutions containing lithium and various minerals such as spodumene, petalite and lepidolite. Lithium is recovered and utilized in various applications in the form of its salt. There is little use for metallic lithium.

Spodumene, i.e. lithium aluminum silicate, LiAlSiiO6 (LiiOAkOsASiCL), is of particular interest because of its relatively high content in ore concentrate and lithium is readily separable by extraction with, for example, sodium carbonate by pressure extraction or by use of concentrated mineral acid. For example, after purification with an ion exchanger, a very pure product, especially pure lithium carbonate, is recovered.

Spodumene occurs naturally in nature as alpha-spodumene, which must be converted to beta-spodumene before lithium separation to improve solubility. The crystal shape change is achieved by heat treatment. Thus, the lithium carbonate manufacturing process generally involves the step of heating the spodumene concentrate to a temperature of at least 800 ° C, typically 800 to 1100 ° C. The thus obtained beta-spodumene concentrate is suspended in water to form a slurry, after which the desired lithium compound, such as lithium carbonate, can be produced, for example, by pressure extraction using sodium carbonate.

The patent literature describes methods for carrying out a heat treatment for crystalline conversion. CA Application Publication No. 1297265 discloses a solution in which 1-10 mm granules are processed in a circulating mass reactor. The amount of recycle gas required in the process is quite high and oxygen must be added at many points separately. As a result, the energy consumption of the process and the fuel used to produce heat, respectively, are high, which increases the environmental impact of e.g. through issues. US2013 / 0042438, for its part, discloses a process for the production of beta-spodumene from alpha-spodumene by heat treatment using a concentrate or ore having a particle size of 20-1000 µm as a solution above. Such small granules are treated in a fluid bed bed at 800-1000 ° C. Oxidizing gases are used for fluidization.

The known solution requires that a feed having a narrow grain size distribution be fed to the reactor in order to be able to uniformly fluidize the solid. The solution is not applicable to cases where the concentrate contains, for example, coarse grain size material together with a fine fraction starting material obtained by precipitation or flotation or flotation.

A further problem with heat treatment is that spodumene-related impurities such as sidewalk, quartz and feldspar can easily be agglomerated during extended heat treatment, which makes lithium extraction difficult. On the other hand, too short a heat treatment may leave a significant part of the spodumene in the form of an alpha-spodumene, thus reducing the average yield of the preparation.

Summary of the Invention

It is an object of the present invention to eliminate at least some of the drawbacks associated with the prior art and to provide a novel solution for the preparation of a beta-spodumene from an alpha-spodumene-containing feedstock by heat treatment.

The invention is based on the idea that the alpha-spodumene is fed into a heating zone, where the heat required for crystal conversion is introduced by indirect heating.

At least part of the heat is then preferably introduced by means of spacers, i.e., heat transfer bodies, which are capable of exerting a spodumene material and a grinding action.

In the heating zone, the concentrate temperature is maintained below the agglomeration temperature of the spodumene material. This temperature setting is influenced not only by the spodumene material contained in the starting material, e.g., by the spodumene granules it contains, but also by the side stone and the excipients such as quartz and feldspar.

An apparatus comprising a rotary drum furnace in which the feedstock containing the alpha-spodumene material can be heated at a temperature above 800 ° C to convert the alpha-spodumene to the beta-spodumene can be used to carry out the invention. The drum furnace has a jacket-enclosed furnace space which is connected to and opens a spacer feed tube for feeding hot spacers into the furnace heated alpha-spodumene material. The opposite end of the spacer feed tube is connected to a heating furnace where the temperature of the spacer can be raised before being fed to the drum oven. The drum furnace is further provided with a discharge tube for removing heated spodumene material from the drum furnace. Preferably, the material obtained from the exhaust pipe is divertable to a screen where the spacers used for heat transfer are separable. More specifically, the method according to the invention is essentially characterized by what is stated in the characterizing part of claim 1.

The solution of the invention achieves considerable advantages. When heat is indirectly introduced, alpha-spodumene can be converted to beta, e.g., at 950-1080 ° C with a short residence time. By keeping the temperature in the area in question, conversion can be achieved without agglomeration, in particular without agglomeration of the limestone and the excipients. By using heat-transferring and transferring solid bodies which are hard enough to exert a mechanical action on the starting material, such as a grinding action, heat transfer can reduce the adhesion of the putty spodumene to the metal surfaces of the furnace. Thus, the heat transfer bodies significantly reduce, or even substantially prevent, the adherence of the spodumene to the inner walls of the drum oven used for heating. By using pieces having an average size larger than the spodumene, the heat-generating pieces can be separated after heating by screening, possibly removing the rock, quartz, and other lime material from the spodumene.

The present solution can handle flotation concentrate, heavy medium concentrate and mixtures thereof, as well as crushed ore alone, whereby the grain size distribution of concentrate or ore may vary over a wide range which is not possible with the known solutions mentioned above.

For the above reasons, the process is efficient and energy efficient; the converted spodumene from the heating zone is well removed and, since the limestone and the excipients are not agglomerated, their separation from the heating zone removal can be accomplished, for example, by cost-effective screening, as noted above.

In the following, a detailed description of the method and apparatus will be taken with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 shows a simplified process diagram of one exemplary embodiment.

applications

As will be apparent from the foregoing, the present technology is generally associated with the production of lithium carbonate. The starting material is a lithium-containing mineral, spodumene. For the preparation of lithium compounds, spodumene is quite advantageous because it has a relatively high lithium content and is easily extracted from lithium. In particular, the technology relates to the step of heat treating such a process wherein the spodumene concentrate-containing material is heated to effect spodumene phase transformation.

The lithium carbonate production process begins with mechanical pre-treatment. The mined ore is pre-crushed in the mining area and the side stones are removed from the aggregate, for example by magnetic separation or optical sorting. The crush is then comminuted, usually by grinding or crushing. Grinding may be accomplished by a mill such as rod or ball mills or a combination thereof and crushing by a cone or roller crusher. Of course, other devices and equipment for grinding and crushing hard material can also be used.

The spodumene is preferably separated from the ground ore by flotation.

Yawning can be done by conventional flotation in the aqueous phase, but it is also possible to do the separation and enrichment of this stage by heavy medium enrichment. Commonly available concentrate has a grain size (average grain size) in the range of 0.1 to 20 mm, in particular about 0.6 to 6 mm.

The terms "material containing alpha-spodumene granules", "(alpha) -spodumene material" and "alpha-spodumene starting material" as used in the present context include alpha-spodumene concentrate, for example, in addition to the concentrate obtained as described above, also - precursor and ore.

Thus, in one embodiment, the starting material for the process is an alpha-spodumene concentrate.

In another embodiment, the starting material is precursor concentrate. Pre-concentrate is a fraction obtained from ore by pre-enrichment, for example by separation of heavy medium. A significant proportion, for example about 30-50% of the feed mass obtained from the pre-crushing and possibly grinding of the ore can typically be removed as waste. The precursor concentrate can be heat-treated as such, followed by recovery of the resulting beta-spodumene from the resulting material, e.g., by screening enrichment.

In a third embodiment, the starting material is ore. The pre-crushed and optionally comminuted ore may be heat-treated as such, followed by recovery of the resulting beta-spodumene from, for example, screening enrichment. "Screening concentrate" means separating and recovering the desired granules through one or more sieves.

After mechanical pre-treatment, the alpha-spodumene material is then preferably de-humidified at 150-400 ° C. An oven (preheating oven) can be used to remove moisture. The furnace may be heated, for example, with biogas, flue gas, LPG, or converter concentrate cooling gas, or with a combination of the above heat-releasing gases. However, it is also possible to heat the dehumidifying furnace with conventional, e.g. solid or liquid fuels.

The spodumene material is heat treated to convert the crystal structure from an insoluble α form to a soluble β form. Typically, material containing alpha-spodumene granules is heated in a heating zone at a temperature above 800 ° C to effect phase transformation of the alpha-spodumene. The alpha-spodumene of the material used contains at least some iron in its crystal lattice as an impurity. The main species of the quartz mineral are quartz (S1O2) and alkaline earth alkaloids, i.e. albite (NaAlSTOx) and potassium feldspar (KAlSfOx). The starting material may also contain limestone particles from the outside of the ore (= limestone).

In the heating zone, the temperature of the spodumene material and the spodumene granules contained therein are maintained below the agglomeration temperature of the (these) concentrate. Thus, the alpha-spodumene is preferably subjected to phase transformation at a temperature of 950-1080 ° C, preferably 950-1050 ° C.

In one embodiment, the heating zone comprises a first zone raising the temperature of the alpha-spodumene granules to at least 800 ° C but below the temperature required for the phase transformation of the alpha-spodumene and a second zone raising the temperature to the temperature required for the phase transformation of the alpha-spodumene.

In the first embodiment, the heater employs a plurality of heater devices that are tracked at multiple locations. For example, at least two series-tracked ovens, such as a drum oven, may be used, the alpha-spodumene fraction being first fed to the first zone forming the first zone, raising the granule temperature of the alpha-spodumene fraction to at least 800 , raising the temperature to at least 950 ° C.

The second furnace, in turn, may be divided into two heating zones, whereby the temperature of the alpha-spodumene fraction is gradually increased to at least 950 ° C.

The above-mentioned ovens are preferably drum ovens suitable for continuous operation. These drum ovens typically have a shell oven space.

Typically, the drum furnace used in the present technology, for example as a preheating, conversion and cooling zone, comprises a rotatable cylinder or drum, which may be from 1 to 30 meters in length and an internal diameter (i.e., diameter of the furnace) of about 0.1 to 5 meters. can be fed to the drum feed end and the treated material can be discharged from the opposite end of the drum, i.e. its outlet end.

Preferably, the drum is positioned at an angle such that, viewed from the drum feed end, the center axis of the drum forms an acute angle with respect to the horizontal, for example the angle may be about 0.1-20 degrees, e.g. 5-15, relative to the horizontal. The residence time in the furnace can be about 1-180 minutes and the rotation speed of the drum around the central axis is about 1-50 rpm.

The length of the drum, the angular position of the center shaft, and the length and speed of rotation of the drum are selected according to the material being processed and its amount.

In one embodiment, thermal energy is introduced into the conversion zone by means of heat accumulating and releasing means. Preferably, the spacers are made of a hard material such as metal, ceramic material or rock material. The spacers may have a regular geometric shape. They may be cylindrical, cubic or spherical. The spacers may also be three-dimensional bodies whose appearance is irregular and undefined. They are generally larger in size than the average grain size of the process input so that they can be mechanically separated, e.g., by screening for conversion zone removal. Typically, at least 90%, in particular at least 95%, preferably at least 99%, of the spacers are 6 mm or larger in size, most preferably at least 90%, especially at least 95%, preferably at least 99%, of 20 mm or larger.

The heating step is further examined below with reference to the drawing.

After the heating zone, further enrichment of the beta-spodumen by screening may be performed. In a preferred embodiment, the exit of the heating zone is screened to separate sidestone and limestone, such as quartz and feldspar, from the beta spodumene.

The resulting β-spodumene can be recovered in a manner known per se.

In one embodiment, lithium is dissolved by a continuous sodium carbonate pressure leaching process. The dissolution can be carried out, for example, in an aqueous solution of sodium carbonate (Na 2 CO 3) at a temperature of 180-250 ° C, especially 200-220 ° C and a pressure of 10-30 bar, especially about 20 bar.

In pressure leaching, an ion exchange reaction occurs, in which the sodium ions replace the lithium ions in the lattice of the spodumene to form a synthetic silicate, the analyte (NaAlSiiCVEEO). Lithium, in turn, is transferred to the sodium carbonate solution to form insoluble lithium carbonate (L12CO3).

The pressure leaching products are recovered and cooled to a selected temperature, generally operating at ambient temperature, most preferably operating at about 20-25 ° C. Carbon dioxide is added to the suspension at a pressure of 5 to 20 bar, in particular about 8 to 11 bar, to form a soluble lithium hydrogen carbonate (L1HCO3) in the liquid phase. The solid solution is first filtered off from the resulting solution, and then L1HCO3 is crystallized to give solid lithium carbonate.

The end product is high purity lithium carbonate having a purity of more than 99.9%, preferably at least 99.99%.

Methods for recovering lithium carbonate and purifying lithium bicarbonate are described, for example, in WO 2010/103173 and WO 2013/140039.

Reference will now be made to the accompanying drawing, which illustrates one exemplary hardware solution suitable for performing phase transformation of an alpha-spodumene.

According to the drawing, the apparatus comprises three series-connected heat transfer zones, namely a preheating drum 1, a conversion drum 2 and a cooling drum 3.

In the solution of Figure 1, a combustion boiler 8 is used to generate the heat needed in the process, where organic material such as biofuel is burned. The steam boiler 9, in turn, produces the pressurized steam needed for power generation 10. The oxygen plant 7, in turn, separates oxygen from the air. It should be emphasized that other solutions can be used instead of these installations to generate the required heat.

The drums 1-3 are typically rotatable about their central axis and are preferably mounted in an angular position so that the material to be processed will pass through them under gravity. The drums can have the same dimensions.

The conversion drum can have a length of 2 to 25 m, especially about 3 to 20 m, for example 4 to 15 m. It has a furnace space diameter of, for example, 0.1 to 5 m, such as 0.5 to 3 m.

In one embodiment, the preheating drum is at least somewhat shorter in length than the conversion drum, e.g., 0.1 to 0.9 times the length of the conversion drum. In one embodiment, the preheating drum is larger in diameter than the conversion drum, e.g., 1.1 to 3 times the diameter of the conversion drum.

In one embodiment, the cooling drum is at least somewhat shorter in length than the conversion drum, e.g., 0.1 to 0.9 times the length of the conversion drum. In one embodiment, the cooling drum is larger in diameter than the conversion drum, e.g., 1.1 to 3 times the diameter of the conversion drum.

The preheating drum designated by reference numeral 1 removes moisture from the alpha-spodumene material at about 150-400 ° C. For heating, for example, hot flue gas from the next step, i.e. the conversion drum 2, is used, as shown in the figure.

From the preheating drum, the material is fed to a jacketed 2 'conversion drum 2, which forms a heating zone for performing the phase transformation of the alpha-spodumene. In the drum oven, the material containing the alpha-spodumene granules can be heated to a temperature of 800 ° C, preferably at least 950 ° C.

The drum is divided into two parts, whereby the first part of the drum - in the direction of concentrate travel - is heated by the flue gases, while the latter part, which constitutes the actual conversion zone, is heated by indirect heating. Part of the heat is supplied by electric heating 12, in particular electrical resistors, and some heat is provided by means of charge and release means 13. In this way, heat is introduced into the drum furnace through its casing and further by radiation.

The drum furnace has a furnace space 2 'provided with an alpha-spodumene granule inlet 14, surrounded by a jacket 2' and further having a beta-spodumene outlet 15.

The furnace jacket 2 'has a heating gas inlet 16 and a heat release gas outlet 17 for introducing heat into the mmpu furnace through the jacket,

In the heating zone 2, the concentrate temperature is kept below the agglomeration temperature of the minor constituents contained in the concentrate, such as limestone and harm. Spodumene concentrate typically contains gray quartz and feldspar and similar siliceous materials and minerals that may agglomerate under heating.

The heating zone 2 is fed with an alpha-spodumene fraction having an average grain size of 0.5-6 mm.

As stated above, the invention can handle a feed having a wide grain size distribution. Thus, in one embodiment, a first alpha-spodumene grain having an average grain size of 0.5-6 mm and a second alpha-spodumene grain having an average grain size of 0.02-1 mm are fed into the heating zone, wherein the first and second grain particles are fed to the heating zone simultaneously or sequentially. . The heat-generating spacers 13 are heated in a heating unit 11 of the pieces, which is heated by the flue gases which, in the case illustrated, are obtained from the combustion boiler 8, which for example burns biofuel. The drum furnace has a hot spacer feeder 18 which opens into a jacket-defined furnace space for feeding spacers to the oven-heated alpha-spodumene granules, wherein the spacer feeder is connected to an oven 11 where the spacer temperature can be increased. The spacers release their heat to the material to be heated. Most preferably, the heat-generating spacers 13 are of metal, ceramic, or rock material, preferably the spacers are cylindrical, cubic, spherical, or of indeterminate shape. To provide a mechanical effect on the spodumene, the spacers have a hard surface. The spacers mix with the material to be treated and exert a grinding effect on the spodumene granules as the drum rotates. At the same time, the spacers scrape the putty spodumen from the surface of the drum and prevent the spodumen from depositing on the inside of the drum.

My beta spodumene is recovered as a product of the heating zone (deletion) via outlet 15. This is connected to a screen 4, which allows the spacers used for the introduction of heat to be separated from the outlet.

In one embodiment, the screen 4 separates the spacers and allows other material to pass through. The screen size of the screen 4 can therefore be selected according to the size of both the feed and the spacers.

In one embodiment, a screen size of up to 20.0 mm, and in particular 6.0 mm or greater, is selected to effectively separate the spacers.

The foregoing has the advantage that, when material having an average grain or particle size of 0.5 to 6.0 mm is introduced into the process, all ore crush is made to pass through screen 4, thereby preventing, for example, the passage of ore or limestone or lime which may agglomerate or melt with spacers in the heating furnace 11.

The spacers to be separated from the heating zone effluent are led without heating to the heating 11 to raise their temperature to a preselected temperature, and then recycled in the heating zone for reuse.

Based on the foregoing, in one embodiment, the product (effluent) to be removed from the heating zone is first screened with a screen 4 having a screen size of 6.0 mm or larger to separate the heat-producing spacers.

After optional cooling, pass the passed portion through a second sieve 5.

In one embodiment, a beta-spodumene is prepared comprising granules which pass through a sieve having a sieve size of at least 0.3 mm and at most about 1.2 mm, preferably about 0.5 to 1 mm, e.g. about 0.7 mm.

Preferably, the second screen 5 has a screen size of about 0.3 to 1.0 mm (e.g., about 0.7 mm), whereby the beta-spodumene is recovered as part of the second screen.

The resulting beta-spodumene is cooled 6 before or after the second screen to a temperature of about 100-250 ° C at which time it is recovered. Reference numeral 6 denotes a thermal silo intended to maintain the recovered spodumene at a desired temperature. The cooling drum 3 may be as shown in the drawing, in which, in a first step, the product which has passed through the heating zone 2 and the first screen 4 is cooled first by gas and then by water cooling. The gas is obtained, for example, from an oxygen plant 7, in which the nitrogen in the air is separated from the oxygen, whereby the nitrogen can be used as a gas cooling medium for the cooling drum. Oxygen, in turn, is used to burn biofuel in combustion unit 8. The beta-spodumene product from cooling is screened through another screen 5, as described above. The beta-spodumene thus obtained, typically 100-250 ° C, is subjected to a leaching treatment, in which the lithium contained therein is leached.

As stated above, the heating zone may be two-piece or may consist of two heating zones connected in series.

In one preferred embodiment, the drum furnace 2 shown in Figure 1 is divided in the middle by radiation plates which thermally separate two zones having different temperatures. The heat accumulating and releasing spacers can be fed behind the radiation plates (in the direction of the spodumene).

Industrial Applicability

The present solution is suitable for the production of beta spodumene. Beta-spodumene, in turn, can be used to make lithium compounds suitable, for example, for battery and accumulator applications.

Reference Number List 1. Preheated drum 2. Conversion drum 2 'Sheath 2 ”Oven space 3. Cooling drum 4. Screen 6.0 mm 5. Screen 0.7 mm 6. Thermal silo 7. Oxygen plant 8. Biofuel 9. Steam boiler 10. Electricity generation 11. Heating of spacers 12. Electrical resistors 13. spacers 14. Inlet for alpha-spodumene material 15. Outlet for beta-spodumene 16. Gas inlet 16 17. Gas outlet

reference Publications

CA 1297265 US 2013/0042438 WO 2010/103173 WO 2013/140039

Claims (28)

A process for the production of a beta-spodumene from a material containing alpha-spodumene granules, comprising: - heating the material containing the alpha-spodumene granules in a heating zone at a temperature above 800 ° C to convert the alpha-spodumene to beta-spodumene, characterized in that heating, - at least part of the heat is introduced by means of spacers capable of exerting a grinding action on the spodumene granules, and - in the heating zone, the temperature of the material containing the alpha-spodumene granules is kept below mm. the agglomeration temperature of the material containing gray rock, quartz and feldspar. Method according to Claim 1, characterized in that an alpha-spodumene fraction having an average grain size of 0.5 to 20 mm is fed into the heating zone. Method according to claim 1 or 2, characterized in that a first alpha-spodumene grain having an average grain size of 0.5-20 mm and a second alpha-spodumene grain having an average grain size of 0.02-1 mm are fed into the heating zone, wherein the first and second grain fractions are fed to the heating zone either simultaneously or sequentially. A method according to any one of the preceding claims, characterized in that a beta-spodumen is prepared comprising granules which pass through a sieve having a sieve size of at least 0.3 mm, preferably 0.5-1.2, typically about 0.7 mm. Method according to one of the preceding claims, characterized in that the beta-spodumene is recovered as a product (deletion) to be removed from the heating zone. A method according to any one of the preceding claims, characterized in that the outlet of the heating zone is screened to separate a limestone such as quartz and feldspar from the beta-spodumene. Method according to any one of the preceding claims, characterized in that the heat-producing spacers do not substantially pass through a sieve having a sieve size of 1.0 mm. Method according to one of the preceding claims, characterized in that the heat-producing spacers are made of metal, ceramic material or rock material, preferably the spacers are cylindrical, cubic, spherical or of indeterminate shape. Method according to one of the preceding claims, characterized in that the product to be removed from the heating zone is first screened with a sieve having a mesh size of not more than 20.0 mm, in particular 6.0 mm or larger, and after the optional cooling, a second sieve having a mesh size 0.3-1.0 mm, whereupon the beta-spodumene is recovered as a passage through the latter sieve. Method according to one of the preceding claims, characterized in that the outlet of the heating zone is separated by sieving, for example using a sieve with a mesh size of not more than 20.0 mm, in particular 6.0 mm or larger, to a preselected temperature and then recycled in the heating zone for reuse. The process according to any one of the preceding claims, characterized in that the beta-spodumene is cooled to a temperature of about 100-250 ° C before or after the second screen, at which temperature it is recovered. Process according to Claim 11, characterized in that the beta-spodumene of 100-250 ° C is subjected to a leaching treatment, in which the lithium contained therein is separated by insoluble matter. Method according to one of the preceding claims, characterized in that the heating zone comprises at least one jacketed drum oven in which the material containing the alpha-spodumene granules is heated to a temperature of 800 ° C, preferably at least 950 ° C. Method according to Claim 13, characterized in that heat is introduced into the drum furnace through its casing and possibly further by irradiation. Method according to Claim 13 or 14, characterized in that heat produced by electric resistors is introduced through the casing of the drum furnace. The process according to any one of the preceding claims, characterized in that the heating zone comprises at least one first zone in which the temperature of the alpha-spodumene granules is raised to 600-800 ° C but below the temperature required for phase transformation of the alpha-spodumene and a second zone in the temperature required for the phase transformation of the spodumene. A method according to claim 16, characterized by two or more first zones arranged in series. A method according to claims 16 and 17, characterized in that heat is supplied to the first zone by indirect heating, for example by using hot flue gases as a heat-generating medium. Method according to one of Claims 16 to 18, characterized in that at least two series of drum ovens are used, the alpha-spodumene fraction being first fed to the first drum forming the first zone, wherein the temperature of the granules of the alpha-spodumene material is raised to at least 800 ° C. wherein the effluent of this drum furnace is led to a second furnace forming a second zone, wherein the temperature is raised to at least 950 ° C. Method according to claim 19, characterized in that the second drum furnace is divided into two heating zones, wherein the temperature of the alpha-spodumene fraction is gradually increased to at least 950 ° C. A method according to any one of the preceding claims, characterized in that the alpha-spodumene of the material used contains at least some iron as impurity in its crystal lattice. A method according to any one of the preceding claims, characterized in that in the heating zone the temperature of the alpha-spodumene material and the spodumene granules contained therein is maintained below the agglomeration temperature of the material. Method according to one of the preceding claims, characterized in that in the heating zone the alpha-spodumene is subjected to phase transformation at a temperature of 950-1080 ° C, preferably 950-1050 ° C. A method according to any one of the preceding claims, characterized in that the temperature of the alpha-spodumene fed into the heating zone is about 600-900 ° C. Method according to one of the preceding claims, characterized in that 10 to 95% of the temperature of the alpha-spodumene from 800 ° C to the temperature required for phase transformation is introduced into the heating zone by heated spacers. A method according to any one of the preceding claims, characterized in that the phase transformation is carried out in a rotatable drum furnace, wherein the spacers exert a scraping action on the inner wall of the drum to prevent adherence of the spodumene material and the spodumene granules contained therein. A method according to any one of the preceding claims, characterized in that the material containing the alpha-spodumene granules is preheated at about 150-400 ° C to introduce moisture into the heating zone. A method according to any one of the preceding claims, characterized in that the material containing the alpha-spodumene granules is an alpha-spodumene concentrate, precursor or comminuted ore. claim: