KR20210080057A - Heat treatment method of spodumene - Google Patents

Abstract

According to one embodiment of the present invention, a spodumene heat treatment method comprises a step of heat-treating α-spodumene at a temperature condition of 1000°C or less. When α-spodumene is heat-treated at the temperature condition of 1000° C or less for 20 minutes, 50 wt% or more of 100 wt% of α-spodumene is phase-transformed to β-spodumene.

Description

Spodumene heat treatment method

The present invention relates to a method for heat treatment of spodumene. More specifically, it relates to a spodumene heat treatment method capable of controlling the phase transition temperature and rate of spodumene.

Lithium is mainly extracted from brines or ores containing lithium.

Lithium-containing minerals include Spodumene (LiAlSi ₂ O ₆ ), Petalite (LiAlSi ₄ O ₁₀ ), Lepidolite (K(Li,Al,Rb) ₂ (Al,Si) ₄ O ₁₀ (F,OH) ₂ ) and the like. Among them, lithium ore containing spodumene as a main component is relatively widely distributed in nature and has a high lithium content and is used as a raw material for lithium.

Oxygenation is widely used to recover lithium from spodumene. This is followed by heat treatment of lithium ore at 1,000 ^o C or higher, mixing with sulfuric acid and ^{roasting at 200 to 250 o} C, and then water leaching to prepare an aqueous lithium sulfate solution. During water leaching, impurities other than lithium leached from the ore are purified, followed by various processes. It is a method for producing lithium carbonate or lithium hydroxide through

Spodumene has homogeneous abnormalities such as α-phase and β-phase, and it mainly exists as α-phase in nature.

In the sulfuric acid roasting process, where lithium ore is mixed with sulfuric acid and roasted, hydrogen in sulfuric acid and lithium in the ore are ion-exchanged to form lithium sulfate. The α-phase has a structure in which it is difficult to ion exchange hydrogen and lithium in sulfuric acid during sulfuric acid roasting. have. ^{Therefore, heat treatment of 1,000 o} C or higher before roasting sulfuric acid is used to convert the α-phase into a β-phase that is easy to ion-exchange with hydrogen in sulfuric acid.

A technology capable of lowering the transition temperature from α-phase to β-phase and improving the transition rate in the heat treatment process that consumes a lot of energy is required.

The present invention provides a method for heat treatment of spodumene. More specifically, it provides a spodumene heat treatment method capable of controlling the phase transition temperature and rate of spodumene.

The spodumene heat treatment method according to an embodiment of the present invention is a spodumene heat treatment method comprising; heat-treating α-spodumene at a temperature condition of 1000° C. or less, wherein the α-spodumene is subjected to a temperature condition of 1000° C. or less When heat-treating for 20 minutes in α-spodumene, 50% by weight or more of 100% by weight of α-spodumene is a phase change to β-spodumene.

The step of heat-treating α-spodumene at a temperature of 1000° C. or less is, α-spodumene is heat treated in a gas atmosphere consisting only _{of O 2} , CO ₂ , N ₂ , Ar, C0, H ₂ , CH _{4 , or a combination thereof.} may be doing

The step of heat-treating α-spodumene at a temperature of 1000° C. or less may include heat-treating α-spodumene in a gas atmosphere containing less than 1.0% by weight of _{O 2 .} More specifically, in the gas atmosphere, O ₂ may be 0.1 wt% or less.

The step of heat-treating α-spodumene at a temperature of 1000° C. or less may include heat-treating α-spodumene in a CO ₂ gas atmosphere.

In the step of heat-treating α-spodumene at a temperature of 1000° C. or less, the heat treatment temperature may be 850 to 950° C.

The β-spodumene phase-transformed by the heat treatment of α-spodumene at a temperature of 1000° C. or less may be used for lithium extraction.

According to the spodumene heat treatment method according to an embodiment of the present invention, lithium can be efficiently separated from spodumene.

According to the spodumene heat treatment method according to an embodiment of the present invention, in order to easily leach lithium contained in lithium ore, α-phase lithium ore (Spoduemen) produced in nature is heat-treated to β-phase (or virgilite). It should be converted, and during heat treatment, the temperature can be lowered and the conversion rate can be increased.

According to the spodumene heat treatment method according to an embodiment of the present invention, the phase transition rate can be improved and the phase transition temperature can be lowered when converting from α-phase to β-phase (or virgilite) by heat treatment of spodumene in lithium ore. have.

1 is a graph showing the phase transition rate according to the heat treatment time in Comparative Example 1 and Example 1 of the present invention.
2 is a graph showing the oxygen concentration and the phase transition rate with time in Example 2 of the present invention.

In this specification, terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In this specification, the terminology used is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.

In the present specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It means to include one or more selected from the group consisting of.

In this specification, when a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be accompanied in between. In contrast, when a part refers to being "directly above" another part, the other part is not interposed therebetween.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.

In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

In an embodiment of the present invention, the meaning of further including the additional element means that the remaining iron (Fe) is included by replacing the additional amount of the additional element.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The spodumene heat treatment method according to an embodiment of the present invention comprises the steps of heat-treating α-spodumene at a temperature of 1000° C. or less; but, when α-spodumene is heat-treated at a temperature of 1000° C. or less for 20 minutes , 50% by weight or more of 100% by weight of α-spodumene is phase-transformed to β-spodumene.

Each step is described below.

First, α-spodumene is heat-treated at a temperature of 1000° C. or less.

In this step, when α-spodumene is heat-treated at a temperature of 1000° C. or less for 20 minutes, 50% by weight or more of 100% by weight of α-spodumene is phase-transformed to β-spodumene.

The gas atmosphere in this step may be a gas atmosphere consisting only _{of O 2} , CO ₂ , N ₂ , Ar, C0, H ₂ , CH _{4 , or a combination thereof.} More specifically, the heat treatment gas atmosphere in this step may not be an air atmosphere. _{More specifically, by injecting a gas of O 2} , CO ₂ , N ₂ , Ar, C0, H ₂ , CH ₄ , or a combination thereof at a constant rate into a tube furnace in a vacuum state for heat treatment of α-spodumene, a gas atmosphere may be making

More specifically, _{the concentration of O 2} may be 5.0 wt% or less. More specifically, it may be less than 1.0 wt%. More specifically, O ₂ may be a gas atmosphere containing 0.1 wt% or less. If the oxygen concentration is too high, the spodumene transition rate is low or the transition temperature is high. In the absence of oxygen, the spodumene transition rate is fast and the transition temperature can be lowered.

More specifically, it may be a mixed atmosphere _{of O 2} and N _{2 .}

On the other hand, it may be a _{CO 2 gas atmosphere.}

The injection rate may be 0.3L/min to 1.5L/min.

When the heat treatment atmosphere is performed in the gas atmosphere instead of the air atmosphere, the temperature at which the α-spodumene phase changes to the β-spodumene can be lowered, and the phase transition rate can be improved.

In addition, in this step, when the heat treatment time is 50 minutes, the phase transition rate may be 80% or more.

In addition, the heat treatment temperature in this step may be 850 to 1000 ℃. More specifically, it may be 850 to 950 °C. That is, it may be lower than the phase transition temperature in the air atmosphere.

Next, α-spodumene is phase-transformed to β-spodumene in the heat treatment atmosphere. More specifically, when heat treatment is performed at a temperature of 1000° C. or less for 20 minutes, 50% by weight or more of 100% by weight of α-spodumene is phase-transformed to β-spodumene. In addition, when heat-treated for 50 minutes, the phase transition rate may be 80% by weight or more.

The phase-changed β-spodumene in this step may be used for lithium extraction. In order to easily leach lithium contained in lithium ore, α-phase spodumene produced in nature must be heat-treated to convert it to β-phase spodumene. β-spodumene, which has been phase-changed by the method of an embodiment of the present invention, is It can be used for lithium extraction.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example

Example 1 and Comparative Example 1

Lithium ore was prepared for the experiment. The chemical composition of the prepared lithium ore is shown in Table 1. The Li content was 2.53 wt%. The main mineral phase is spodumene (α-phase), and KAl ₂ ( _{AlSi 3} O ₁₀ )(OH) ₂ , Na(AlSi ₃ O ₈ ) and the like are observed as impurities. The component composition unit in Table 1 is weight %.

Li Al Si Ca Mg Na Mn 2.53 12.96 28.85 0.99 0.17 0.41 0.21

About 5 g of lithium ore of the above composition was weighed and placed in an alumina crucible ^{, charged into a tube furnace heated to 900 o} C, taken out after a predetermined time, and cooled in air, followed by analysis of the mineral phase composition.

The tube furnace (diameter 5cm, length 100cm) was ^{maintained at 900 o} C before loading the sample, and then tested in an air atmosphere according to the experimental conditions. What was tested in an air atmosphere is referred to as Comparative Example 1.

In addition, Example 1 was tested under the same conditions as Comparative Example 1, except that the experiment was conducted in a _{CO 2 atmosphere.} At this time, the CO ₂ atmosphere was _{sufficiently purged with CO 2} (g), and then the sample was charged, and the experiment was performed while injecting 0.7 L of _{CO 2 (g) per minute.}

The phase transition rate from α-phase to β-phase (or virgilite) was obtained in the same way as [1-(content of α-phase after heat treatment/content of α-phase in the raw material)]x100, and the content of α-phase was determined after quantification of mineral phase. Lithium minerals (α-, β-phase, Virgilite) were calculated as 100.

Figure 1 shows the phase transition rate from α-phase to β-phase (or Virgilite) with time in a _{CO 2} atmosphere (Example 1) and an Air atmosphere (Comparative Example 1) during heat treatment at ^{900 o C. Air atmosphere (} Comparative Example 1) exhibited a phase transition rate of 58% at 30 minutes of heat treatment time _{, 83% in a CO 2} atmosphere (Example 1), and a phase transition rate of 76% in an air atmosphere (Comparative Example 1) at 1 hour, whereas In the CO ₂ atmosphere (Example 1), the entire phase transition was made from α-phase to β-phase (or Virgilite).

Therefore, during the heat treatment of lithium ore, the CO ₂ atmosphere (Example 1) can improve the phase transition rate from α-phase to β-phase (or Virgilite) than the Air atmosphere (Comparative Example 1), and lower the phase transition temperature .

Example 2

The phase transition rate according to the concentration _{of O 2} in the atmosphere during ^{900 o} C heat treatment was investigated using the same tube furnace and experimental method using lithium ore having the composition of Table 1 above. _{O 2} concentration was adjusted by mixing nitrogen and oxygen, and the injection rate was 0.7L per minute.

Figure 2 shows the phase transition rate with time from α-phase to β-phase (or Virgilite) according to the concentration of _{O 2} during heat treatment. At _{45 minutes, when the O 2} concentration is 0.01% or less, α-phase to β-phase (or Virgilite) ), and as the O ₂ concentration increased, the phase transition rate decreased, resulting in a phase transition rate of 61% in 60 minutes at a _{21% O 2 concentration.}

These results show that _{by controlling the O 2} concentration, the phase transition rate from α-phase to β-phase (or Virgilite) can be improved and the phase transition temperature can be lowered during heat treatment of lithium ore.

The present invention is not limited to the embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains may develop other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (7)

Heat-treating α-spodumene at a temperature of 1000° C. or less;
Spodumene heat treatment method comprising
When the α-spodumene is heat-treated at a temperature of 1000° C. or less for 20 minutes, 50% by weight or more of 100% by weight of the α-spodumene is a spodumene heat treatment method.
According to claim 1,
The step of heat-treating the α-spodumene at a temperature of 1000° C. or less,
The α- _{spodumene heat treatment method O 2} , CO ₂ , N ₂ , Ar, C0, H ₂ , CH ₄ , or heat treatment in a gas atmosphere consisting only of a combination thereof.
According to claim 1,
The step of heat-treating the α-spodumene at a temperature of 1000° C. or less,
The α-spodumene heat treatment method for heat treatment in a gas atmosphere containing less than 1.0% by weight of _{O 2 spodumene.}
4. The method of claim 3,
The gas atmosphere is O ₂ spodumene heat treatment method of 0.1 wt% or less.
According to claim 1,
The step of heat-treating the α-spodumene at a temperature of 1000° C. or less,
The α- spodumene heat treatment method by heat-treating the α-spodumene, CO _{2 gas atmosphere.}
According to claim 1,
In the step of heat-treating the α-spodumene at a temperature of 1000 ° C. or less,
The heat treatment temperature is spodumene heat treatment method of 850 to 950 ℃.
According to claim 1,
α-Spodumene heat treatment at a temperature of 1000 ° C. or less; β-spodumene phase-transformed by the heat treatment method is used for lithium extraction.

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