KR20140064426A - Enrichment of rare earth oxide with smelting reduction process - Google Patents

Abstract

Disclosed is a method for concentrating rare earth oxides through smelting reduction. The method for concentrating rare earth oxides through smelting reduction includes the steps of: preparing rare earth ores; treating the rare earth ores through the smelting reduction; separating smelting reduction-treated pig iron; and separating slag where rare earth elements are concentrated through the separation of the pig iron. Desirably, the rare earth ores contain a large quantity of iron (Fe). Further, the smelting reduction is conducted according to an equation of reaction: iron oxide + carbon → iron (Fe) + CO and an equation of reaction: iron oxide + CO → iron (Fe) + CO². The smelting reduction is desirably conducted in a reducing atmosphere. Furthermore, upon the smelting reduction, cokes or flux may be further added as a carbonaceous reducer. Desirably, the cokes are added by 1.5 times with respect to a theoretical value needed for iron reduction in the ores, and the flux is added to a quantity of 30% or less with respect to the ores.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a rare earth enrichment method using a melt-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for concentrating rare earths, and more particularly, to a method for concentrating rare earths by using a melt reduction method.

It is well known that rare earths are not only very small compared to other metal minerals with different reserves, they are hard to obtain because they are very difficult to separate from ore, and most of them are very expensive.

On the other hand, demand for rare earths is increasing day by day due to demand explosion in various electronic devices.

Therefore, there is a demand for a method of extracting rare earth element from the ore inexpensively.

As a method for obtaining the rare earths, a rare earth containing rare earth is pulverized, and the pulverized ores are subjected to a light selection process such as selective screening, and then a total rare earth oxide (T-REO) , And the desired rare earths are recovered by separating each element by a method such as solvent extraction through a wet leaching process.

According to the conventional method for obtaining rare earths, it is necessary to grind the rare earth-containing mineral particles to a fine level capable of collectively separating the powder to obtain a powder. The obtained powder is then subjected to acid treatment, alkali extraction It is widely known that the dissolution conditions are difficult due to the rare earth-bearing ore.

Also, in consideration of the economical efficiency of the leaching process, the yield of the tourmaline was low due to the fact that the concentrate of rare earths in the concentrate should be concentrated to a certain percentage (for example, 20%) through the tourmaline process, .

Furthermore, in the case of some rare earth minerals, it sometimes takes too much time and / or energy for pulverization, or it is difficult to form a concentrate during the beneficiation process after pulverization.

A prior art related to the present invention is Korean Registered Patent No. 10-0141539 (registered on Mar. 23, 1998).

Accordingly, the present invention provides a process for recovering valuable metals such as rare earths from ores that have been subjected to a minimum amount of beneficiation, which is difficult to conduct beneficial enrichment or can easily be upgraded by simple operation, Thereby preventing a rare earth loss occurring in the process and obtaining a high recovery rate.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above problems, a rare earth concentration method using the melt reduction method of the present invention comprises: preparing a rare earth ore; A step of melting and reducing the rare earth ore using the melt reduction method; Separating the pig iron subjected to the melt reduction treatment; And separating the pig iron so as to separate the slag from which the rare earths are concentrated.

Here, it is preferable that the rare earth oresource is a rare earth ores having a large amount of iron (Fe) component.

Further, the above-mentioned melt reduction method proceeds according to the following Reaction Schemes 1 and 2.

[Reaction Scheme 1]

Iron oxide + carbon → iron (Fe) + CO.

[Reaction Scheme 2]

Iron oxide + CO - Iron (Fe) + CO ₂ .

In addition, the slag in which the rare earths are concentrated may be easily pulverized.

Further, the melting and reducing treatment may be performed in a reducing atmosphere.

Further, in the rare earth concentration method using the melting-reduction method of the present invention, it is preferable to further add a coke as a carbonaceous reducing agent.

Here, if necessary, a flux may be further added as a slag formation promoter.

It is preferable that the melting and reducing treatment is performed at a temperature of 1250 to 1600 占 폚.

The melting and reducing treatment may be performed in an induction furnace, or alternatively, in an arc.

In the rare earth concentration method using the melting and reducing method of the present invention, it is preferable that the coke is added 1.5 times as much as the theoretical value required for iron reduction in the ore.

It is particularly preferable that the solvent is added in an amount of 30% or less of the raw light.

The details of other embodiments are included in the detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention and the manner of achieving them will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings.

It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The present invention is not intended to be exhaustive or to limit the invention to the precise form disclosed, and it is to be understood that the invention is limited only by the terms of the appended claims.

It is to be understood that the same reference numerals refer to the same components throughout the specification and that the size, position, coupling relationship, etc. of each component constituting the invention may be exaggerated for clarity of description.

According to the rare earth concentrating method using the melting and reducing method of the present invention as described above, it is possible to prevent the loss of rare earths generated during the concentrating of the rare earth as well as not to carry out the beneficiation process, and the recovery rate of the rare earth is also high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing a rough procedure of a rare earth concentration method using a melt-reduction method according to a preferred embodiment of the present invention. FIG.
2 is a cross-sectional view schematically showing a melting furnace used in a rare earth concentration method using a melt-reduction method according to a preferred embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the concept of reaching the present invention will be described in comparison with the prior art.

The inventor of the present invention has found that when a content of a rare earth metal such as iron is high in rare earth light (ore), a carbonaceous reducing agent is added to the rare earth light so that iron is preliminarily melted and reduced so that a valuable metal such as iron, And the components which are difficult to be reduced with carbon such as rare earths are concentrated in the slag produced during the melting and reduction, it is thought that rare earths can be easily recovered through the subsequent leaching process .

At this time, since the metal (iron) has been previously reduced and recovered and the crystal water and the like in the ore have been removed, the weight of the slag is reduced, and therefore, the valuable metal which can not be reduced with carbon, such as rare earths, is relatively concentrated.

In addition, the slag is easier to grind than general ores, and since the valuable metals such as rare earths contained in the slag are converted into oxides, the slag can be easily recovered even if a weakly acidic (weakly alkaline) solution is used do.

The inventor of the present invention has completed the present invention with the above-described basic concept in mind.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing a rough procedure of a rare earth concentration method using a melt-reduction method according to a preferred embodiment of the present invention. FIG.

Referring to FIG. 1, a rare earth enrichment method using a melt-reduction method according to the present invention includes a step of preparing a raw light (ST100), a step of melting and reducing the raw light (ST120) (ST140), separating the concentrated slag from the melted and reduced raw material (ST160), and leaching the concentrated slag (ST180).

Prepare the ore

In order to realize the rare earth enrichment method according to the present invention, in the step of preparing the ore light (ST100), as a light source containing a large amount of iron (Fe) component and relatively rich in rare earth component, I prepared the Hongcheon magnetite which can be obtained.

The results of analysis of the components of Hongcheon magnetite are shown in Table 1 below.

As can be seen from Table 1, it was confirmed that about 2.95% of T-REO was contained in Hongcheon magnetite.

In addition, it can be seen that 38.2% of Fe ₂ O ₃ is contained as iron in the magnetite of Hongcheon.

For reference, some of the ingredients considered to be irrelevant to the characteristic constitution of the present invention are excluded from the description of Table 1 above. Therefore, it should be noted that the sum of the above components does not satisfy 100.

Melt-reduction treatment

The step of performing the melting reduction treatment (ST120) is a step of subjecting the above-prepared Honghuan magnetite to a melting reduction treatment in an induction furnace or an arc furnace.

When the amount of the raw light is small, it is preferable to use an induction furnace which is easy to handle.

At this time, the coke of Hongcheon magnetite ore was mixed with coke of 1.5 times the theoretical value required for iron reduction, and the mixture was heated to a temperature of 1500 ° C or higher and melted. .

Further, in order to make slag generation active while lowering the melting point of slag, it is more preferable to add an appropriate amount of SiO ₂ , CaO, Al ₂ O ₃ , MgO or the like as flux by referring to the ternary phase diagram desirable.

The solvent is added in order to improve the physical properties of the slag when the ore is dissolved, so that the reduction reaction can be smoothly performed. When the concentrated rare earths are subjected to the leaching treatment, the solvent effectively leaches the rare earths.

Pig iron (Fe) separation

The step of separating the pig iron (ST140) is a step of recovering only the pig iron from the cooled ores.

According to this step, the content of the iron (Fe) component, which occupies a considerable amount in the ore, is significantly lowered, and the concentration of the slag is relatively increased.

Separation of concentrated slag

The step of separating the concentrated slag (ST160) is a step of recovering the concentrated slag from the cooled ores.

Leaching treatment

The step of leaching the concentrated slag (ST180) is a step of leaching the concentrated slag using acid or alkali.

According to the present invention, in the case of a slag in which rare earths are concentrated, rare earths can be easily obtained even by using a slightly acidic or slightly alkaline solution.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention.

It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Prepare the ore

As described above, the rare earth light used in the present invention was prepared from the Hongcheon magnetite which can be easily obtained in the Hongcheon region of our country.

1 kg of the ore used in the examples of the present invention was prepared.

Melt-reduction treatment

The raw ore prepared as described above, silica (SiO ₂ ) as a slag formation promoting agent, and a reducing agent were melt-reduced in the melting furnace shown in Fig.

At this time, the slag promoter and the reducing agent were used in sufficient amounts to generate slag and reduce iron in the ore considering the chemical reaction during the melting and reduction.

Specifically, 20.4 g of silica as slag promoter and 140 g of coke as a reducing agent were charged to 1 kg of ore.

At this time, the temperature of the induction furnace was maintained at about 1500 ° C, and the reaction was maintained for about 3 hours and cooled.

Here, the structure of the melting furnace used in this embodiment will be described with reference to Fig.

The melting furnace shown in the figure is an induction furnace and includes a crucible 200 in the form of a 형상 shape. The crucible 200 is provided with a crucible 200 in the crucible 200, A flux is added.

An induction coil 220 is installed outside the crucible 200 and the operation of the induction coil 220 is controlled by a control unit 260. The construction of the induction furnace is considered to be obvious to those skilled in the art, and a further explanation thereof will be omitted. Likewise, the description of the structure of the arc is omitted.

The temperature of the crucible 200 is controlled by the thermometer 240 installed in the crucible 200 and the controller 260.

At this time, the melting temperature of the crucible 200 was set at 1250 to 1600 ° C, the temperature was raised to 15 minutes, and the melting temperature was maintained at about 30 minutes.

If the melting temperature of the crucible 200 is less than 1,250 DEG C, melting of the orginal light becomes insufficient. If the melting temperature of the crucible 200 exceeds 1,600 DEG C, corrosion of the crucible 200 itself may occur So that the melting of the ore is negatively affected.

Further, when the arc was used, 30 kg of ore, 3.3 kg of zircon, and 4.2 kg of coke were injected and subjected to melt reduction. As a result, the phase separation was not complete, but the metal phase was 5.98 kg and the slag was 20.5 kg .

The amount of T-REO in the concentrated slag obtained according to an embodiment of the present invention will be described later with reference to Table 2.

The mechanism of the chemical reaction occurring in the above-mentioned melt-reduction reaction is as follows.

First, a metal oxide (Fe ₂ O ₃ in the raw material in the present embodiment) is reduced to a metal (Fe in this embodiment) and CO gas by a coke added as a reducing agent or the like.

[Reaction Scheme 1]

Metal oxide + carbon → metal (Fe) + CO.

In addition, a reduction reaction of the metal oxide and carbon monoxide (CO) occurs at about the same time or simultaneously with the following.

[Reaction Scheme 2]

Metal oxide + CO → metal (Fe) + CO ₂ .

It should be noted that the melting and reducing process of the present invention is a process in which carbon or carbon monoxide (CO) reacts with oxygen of a metal oxide at a high temperature to produce CO or CO ₂ .

That is, when O ₂ in the outside air flows in the melting and reducing process, these O ₂ react with the reducing agent (and CO) first, and the melting and reducing process of the orginal light is not smooth. Therefore, Is particularly preferable.

In this example, both the induction furnace and the arc furnace were tested. The results are shown in Table 2 below with and without the flux.

On the other hand, although the use of the flux used in the present invention has been described above, it should be noted that it is most advantageous to not add a solvent when the rare earths are concentrated.

However, it is not necessary to add a solvent if the composition of the ore has no problem in slag formation. However, most of the ore containing rare earths should be added with a certain amount of solvent in the melting and reduction.

The solvent used in this embodiment is typically SiO ₂ , and other CaO, MgO, or the like may be used.

In this case, the amount of the solvent to be added may vary depending on the composition of the raw ore, so that it is impossible to uniformly determine the amount of the solvent, but use of a solvent of 30% or more of the raw ore is meaningless in achieving the object of concentration of rare earths, The upper limit of addition of the solvent is preferably 30% of the raw light.

In the examples of the present invention, 2% of solvent was added.

Pig iron (Fe) separation

As described above, the pig iron (Fe) was firstly separated while cooling the raw light melted in the crucible 200.

When the pig iron is first removed, the relative enrichment of the rare earths is achieved.

The pig iron is separated from the metal oxide while being reduced by the carbonaceous reducing agent at the time of the melt reduction reaction.

At this time, the component that is not reduced by the carbonaceous reducing agent, that is, the rare earth component, remains mostly concentrated in the slag.

Separation of concentrated slag

As described above, when pig iron is firstly separated from the crucible 200, the slag in which rare earths are concentrated remains.

At this time, since the metal (iron) has been previously reduced and recovered and the crystal water and the like in the ore have been removed, the weight of the slag has been reduced, and thus the valuable metal which can not be reduced with carbon, such as rare earth, is present in a relatively concentrated state .

This slag is easier to crush than ordinary ores and the valuable metals such as rare earths contained in the slag are converted into oxides. Therefore, the use of strongly acidic (strong alkaline) solutions for the conventional ore Rare earths can be easily recovered through a leaching treatment process using a relatively weakly acidic (weakly alkaline) solution.

analysis

In Table 2, the slag obtained by the rare earth concentration method using the melting and reducing method of the present invention was analyzed to show each component as compared with WONKANG (Hongcheon magnetite).

From Table 2, it can be seen that the T-REO of the orginal light was 2.95%, but in the case of the induction furnace with a flux added (2% SiO ₂ added as solvent) for 3 hours, ₂ ) and 140 g of coke were charged. When the reaction was maintained at 1500 ° C. for 3 hours, 288.2 g of pig iron was recovered and the slag was 416 g.

The T-REO content of the slag at this time is 8.36%, which indicates that the rare earths have been concentrated at a level of about 3 times that of T-REO at 2.95% in the ore.

As described above, 30 kg of ore, 3.3 kg of zeolite (SiO ₂ ) and 4.2 kg of coke were charged in the case of arc furnace (addition of 2% SiO ₂ as a solvent) for 2 hours at 1500 ° C. When kept, the pig iron was 5.98 kg and the slag was 20.5 kg.

The T-REO in the slag at this time represents 5.84%, which indicates that the rare earths are concentrated at a level of about twice that of T-REO at 2.95% in the ore.

At this time, as described above, in order to concentrate the rare earth, which is the object of the present invention, it is preferable to minimize the addition amount of the solvent as the slag formation promoting agent.

On the other hand, from Table 2, it can be seen that in the case of the induction furnace, the enrichment ratio of the rare earth is high, because the reduction rate of the iron (Fe) is high.

That is, in the case of rare earths, the entire amount of the rare earths is not reduced in the melting and reducing process, but enters the slag. In this process, the pig iron is reduced and recovered. As a result, when the content of slag is reduced, the rare earths are concentrated.

Therefore, it is preferable to minimize the addition amount of the solvent since the amount of the slag calculated when the addition amount of the solvent increases increases the concentration effect of the rare earth.

In the case of the induction furnace, the reaction proceeds in a state in which the raw material and the reducing agent are mixed in the high-density graphite crucible and the lid is covered and closed. Thus, the reducing atmosphere in the crucible is maintained, for example, the inflow of oxygen is blocked and the CO partial pressure is increased.

As a result, it can be seen that the reduction rate of iron (Fe) increases, the weight of the slag decreases, and the concentration of rare earths increases.

However, when the arc furnace is small, there is a problem that it is difficult to maintain the reducing atmosphere in the crucible during the melting and reducing process as described above because the ore layer is structurally difficult to seal the crucible upper part and the unmelted ore layer is thin.

Therefore, the reduction ratio of the pig iron (Fe) is relatively decreased, and the iron content in the slag is increased, so that the concentration ratio of rare earth is relatively lowered.

Therefore, in the preferred embodiment of the rare earth concentration method using the melting-reduction method of the present invention, it is preferable to use an induction furnace which is easy to maintain a reducing atmosphere.

However, an arc furnace may be used as long as it is a melting furnace capable of continuously maintaining a reducing atmosphere even if it is not an induction furnace.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible.

Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

200: melting furnace
220: induction coil
240: Thermometer
260:
ST100: Preparation stage of ore light
ST120: Melt reduction step
ST140: Pig separation step
ST160: Concentrated slag separation step
ST180: leaching step

Claims (12)

Preparing a rare earth ore;
A step of melting and reducing the rare earth ore using the melt reduction method;
Separating the pig iron subjected to the melt reduction treatment; And
And separating the slag from the rare earth-enriched slag by separating the pig iron.
The method according to claim 1,
The rare-
A rare earth enrichment method using a melt-reduction method, characterized in that the rare earth element ore is a rare earth element ore containing a large amount of iron (Fe).
3. The method of claim 2,
The melt-
A process for concentrating rare earths according to claim 1, characterized in that the reaction proceeds according to the following Reaction Schemes (1) and (2).

[Reaction Scheme 1]
Iron oxide + carbon → iron (Fe) + CO.

[Reaction Scheme 2]
Iron oxide + CO - Iron (Fe) + CO ₂ .
The method of claim 3,
The slag, in which the rare earths are concentrated,
A method for concentrating rare earths using a melt reduction method, characterized in that pulverization is easy.
The method of claim 3,
The above-
Wherein the rare earth metal is carried out in a reducing atmosphere.
The method of claim 3,
Characterized in that a coke as a carbonaceous reducing agent is further added.
The method according to claim 6,
A method for concentrating rare earths by a melt-reduction method, wherein a flux is further added as a slag formation promoter.
The method of claim 3,
The above-
Wherein said step (c) is carried out at a temperature of 1250 to 1600 ° C.
The method according to claim 1,
The above-
Wherein the rare earth element is carried out in an induction furnace.
The method according to claim 1,
The above-
Lt; RTI ID = 0.0 > a < / RTI > arc.
The method according to claim 6,
The coke,
And 1.5 times the theoretical value required for iron reduction in the ore.
8. The method of claim 7,
The solvent,
The method of concentrating rare earths according to claim 1, wherein the rare earth element is added in an amount of 30% or less based on the raw light.

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