KR20030055506A - A method for manufacturing of cerium hydroxide removal of fluoride from the bastnasite - Google Patents

Abstract

PURPOSE: A method for preparing cerium hydroxide from bastnasite is provided, in which cerium compound is separated through roasting and sulfuric acid leaching of the bastnasite and remove fluorine contained in the cerium compound by using metal salts. CONSTITUTION: In a method for preparing high purity cerium hydroxide from bastnasite, the method comprises the steps of drying and crushing bastnasite; roasting bastnasite, followed by leaching out cerium from the roasted bastnasite with sulfuric acid; separating and recovering cerium by adding sodium sulfate to the sulfuric acid leachate; precipitating cerium sodium sulfate and removing fluorine by adding sodium sulfate and aluminum sulfate to the separated and recovered solution containing cerium fluoride negative ions; and adding a sodium hydroxide aqueous solution to cerium sodium sulfate, wherein quadrivalent cerium ions as well as trivalent rare earth elements are selectively reacted with sodium sulfate in the step of separating and recovering cerium by adding sodium sulfate to the sulfuric acid leachate, TREO (total rare earth oxides) concentration of the leachate is 50 to 100 g/L, addition amount of sodium sulfate is 1.5 to 2.5 equivalents, and reaction temperature is 30 to 60 deg.C, and wherein purity of cerium hydroxide is 99% or more in the step of adding a sodium hydroxide aqueous solution to cerium sodium sulfate.

Description

A method for manufacturing of cerium hydroxide removal of fluoride from the bastnasite}

The present invention relates to a method for producing cerium hydroxide from which fluorine is removed from fluoride rare earth concentrates. In particular, a cerium compound is separated from bastnasite by roasting and sulfuric acid leaching, and fluorine is contained in the cerium compound. The present invention relates to a method for producing cerium hydroxide in which fluorine is removed from a fluorocarbonate rare earth concentrate to be removed using a metal salt.

In general, cerium hydroxide is separated and recovered from the cerium-containing solution in the mixed rare earth-containing solution through the roasting and sulfuric acid leaching process of rare carbonate rare earth concentrate bustnasite, cerium hydroxide which is a raw material of cerium compound from the cerium-containing solution is prepared do.

The cerium hydroxide is required to be highly purified of cerium in order to be used as a raw material for advanced functional materials. In order to manufacture the cerium hydroxide as described above, cerium hydroxide must be highly separated and recovered from the mixed rare earth element.

However, the cerium as described above contains a large amount of fluorine inside when separated and recovered from the cerium-containing solution, and thus, the cerium fluoride is present in the cerium fluoride in the cerium hydroxide in the production process and in the subsequent process such as the cerium compound production. There is a disadvantage in that the purity and performance of the.

The acidity control method and the ion-sieve method were provided as a method of preparing cerium to compensate the above disadvantages.

The acidity control method is to separate cerium from other trivalent rare earth elements by oxidizing cerium from the leaching solution through the decomposition and leaching of rare earth concentrates for the separation of rare earth elements having the characteristic of being oxidized or reduced from trivalent to tetravalent.

However, the acidity control method is a facility that is simple and easy to operate, it is widely used when recovering cerium or impurities are precipitated due to the oxidizing agent used in the oxidation of cerium, contaminating the precipitate, strictly controlling the acidity of the solution There is a downside to it.

In addition, the recovery rate of cerium increases with increasing amount of oxidizing agent, but the purity of cerium decreases due to the co-precipitation of other rare earths. Therefore, in order to obtain high recovery and high quality by acidity control method, two or more stages of oxidative precipitation are obtained. Required.

On the other hand, "the ion-sieve method is used from the sulfuric acid leaching solution, which complements the disadvantages of the acidity control method, and the ion-sieve method uses the characteristics of tetravalent cerium ions.

That is, the sulfuric acid leaching solution contains a large amount of fluorine, which combines with tetravalent cerium to form a cerium fluoride anion, and other rare earth elements exist as trivalent cations.

Therefore, the cation exchange resin is used to adsorb rare earth cations in the leaching solution to the cation exchange resin to separate the cerium fluoride anion from other rare earth elements.

However, the ion-sieve method as described above has the advantages of a higher resolution of cerium and a simpler process compared to the acidity control method. However, since the ion-sieve method is performed in a cation exchange water tower, the cation exchange resin after the adsorption / desorption process of the rare earth ions and the adsorption / desorption process It is a disadvantage that a large amount of waste acid and waste water are generated by accompanying ancillary processes such as acid treatment and water treatment.

An object of the present invention for solving the above problems, by using the acidity control method and ion-sieve at the same time effectively solve the problems revealed in the separation and recovery method of cerium, simplifying the process and shortening the process time of high purity The present invention provides a method for preparing cerium hydroxide from which fluorine is removed from a fluorocarbonate rare earth concentrate for preparing cerium.

1 is a process chart for the production of cerium hydroxide according to the present invention.

FIG. 2 is a graph showing an XRD pattern of CeNa (SO ₄ ) ₂ according to the amount of Na ₂ SO 4 added according to the present invention. FIG.

Figure 3 is a graph showing the particle distribution of CeNa (SO ₄ ) ₂ prepared by the present invention.

4 is a graph showing an XRD pattern of CeO ₂ prepared from CeNa (SO ₄ ) ₂ of the present invention.

5 is a graph showing an XRD pattern of CeO ₂ prepared from fluorine-free CeNa (SO ₄ ) _{2 according} to the present invention.

In order to achieve the above object, the present invention comprises the steps of drying, crushing the fluorite rare earth light;

Oxidizing and roasting the crushed fluorate rare earth light to leach sulfuric acid;

Separating sodium by adding sodium sulfate to the sulfuric acid leaching solution;

Removing sodium cerium sulfate and fluorine by adding sodium sulfate and aluminum sulfate to the cerium solution; and

Provided is a method for preparing cerium hydroxide from which fluorine is removed from a rare carbonate carbonate having a structure comprising the step of adding an aqueous sodium hydroxide solution to sodium cerium sulfate.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, drying and crushing are performed in order to remove moisture of the fluorite rare earth light.

The dried and crushed fluorite rare earth light is subjected to roasting at an appropriate temperature and time, and then the roasted oxide is leached into sulfuric acid at an appropriate concentration.

Subsequently, after distillation of sulfuric acid, distilled water is added to dilute with sodium distilled water to maintain the rare earth ion concentration in the filtered leaching solution at an appropriate concentration.

Subsequently, the cerium is subjected to solid-liquid separation by remaining in solution in the form of a cerium fluoride anion to recover the cerium from the rare earth elements.

Subsequently, since cerium present in the separated and recovered cerium fluoride anion-containing solution is tetravalent, tetravalent cerium is first reduced to trivalent to recover cerium from the cerium fluoride anion.

In the present invention, the reducing agent used hydrogen peroxide in which the product did not affect the contamination after the reaction.

The trivalent reduced cerium combines with anions or optionally added ions in the solution to form an intermediate compound for cerium hydroxide conversion, and when only a reducing agent is added, the trivalent reduced cerium and fluorine combine to form cerium fluoride. Precipitates while forming

However, the cerium fluoride thus formed has a disadvantage in that the conversion rate of the cerium hydroxide is not only reduced, but also difficult to remove by-products such as NaF.

Therefore, the present invention effectively removes fluorine, which may be a problem in manufacturing cerium hydroxide, which is a starting material of a high purity cerium compound, by adding sodium sulfate and aluminum sulfate.

The manufacturing method of cerium hydroxide by the above manufacturing process is demonstrated concretely by an Example.

Example 1

Separation Recovery Method of Cerium Using Sodium Sulfate

TREO (total rare earth oxide) concentration of sulfuric acid leaching solution, the amount of sodium sulfate added and reaction temperature were selected as variables, and the nutritional effects of cerium separation on trivalent rare earth elements precipitated in combination with sodium sulfate.

Separation and recovery of cerium using sodium sulfate is a method of separating and recovering cerium by selectively reacting trivalent rare earth elements other than tetravalent cerium with sodium sulfate.

The above method utilizes the properties of tetravalent cerium ions. The rare earth elements in the leaching solution undergoing the oxidation and sulfuric acid leaching are combined as a cerium fluoride anion as shown in Scheme 1, and the other trivalent rare earth elements are present as cations.

^{Ce 4+ + Re 3+ + 6F -} ---- → [CeF 6] 2- + Re 3+

[CeF ₆ ] ^2- + Re ³⁺ + 2Na ₂ SO ₄ ---- → [CeF ₆ ] ^2- + ReNa (SO ₄ ) ₂ ↓ + 3Na ⁺

Therefore, when sodium sulfate is added to the leaching solution as shown in Scheme 2, trivalent rare earth cations are combined with sodium sulfate to form sodium sulfate rare earth, and the cerium fluoride anion is separated from other rare earth elements.

Such a method has the advantage that the process is simple and the recovery rate and quality of the recovered cerium are high.

In the present invention, sodium sulfate rare earth precipitation of trivalent rare earth ions was carried out while varying the TREO concentration of the leaching solution. Table 1 shows the percentage of cerium elements in the total rare earth elements contained in the solution from which trivalent rare earth ions were removed by ICP analysis according to the TREO concentration change of the leaching solution.

Percentage of Cerium Content and Cerium Recovery Rate of Total Rare Earth in Solution after Elimination of Trivalent Rare Earth Elements by Changes of TREO Concentration in Leachate Solution TREO (g / ℓ) 55 70 105 Ce / TRE (%) 99.7 99.8 96.1 Cerium recovery rate (%) 82.5 82.2 79.3

According to Table 1, after the removal of trivalent rare earth ions with the increase of the concentration of the total rare earth oxides in the leaching solution by adding a certain amount of sodium sulfate, the content of cerium in the total rare earths in the solution showed a significant change up to about 70 g / l TREO concentration. However, the TREO concentration is about 105 g / ℓ can be seen that the content is falling, and the lower the TREO concentration of the leaching solution, the higher the recovery of cerium, so that the TREO concentration is about 70 g / ℓ can be seen that appropriate.

Percentage of Cerium Content and Cerium Recovery Rate of Total Rare Earth in Solution after Removal of Trivalent Rare Earth Elements by Changes in Sodium Sulfate Addition Na ₂ SO ₄ Equivalent 1.0 1.5 2.0 2.5 3.0 Ce Recovery (%) 86.3 82.2 82.2 70.6 73.1 Ce grade 93.2 98.6 99.8 99.7 99.8

Table 2 shows the results of trivalent rare earth removal by changing the amount of sodium sulfate added to the leaching solution at a constant TREO concentration.The recovery of cerium present in the solution after trivalent rare earth removal decreases as the amount of sodium sulfate is increased. Therefore, it is understood that the amount of sodium sulfate added is appropriate in consideration of the recovery rate and the grade.

In addition, as a result of double salt precipitation by changing the reaction temperature, sodium sulfate rare earth precipitates easily occur as the reaction temperature increases, while the purity of cerium increases, whereas the recovery rate of cerium decreases, so the reaction temperature is about 50 ° C. It can be seen that.

Percentage of cerium content and total cerium recovery of total rare earths in solution after removal of trivalent rare earth elements according to reaction temperature Reaction temperature (℃) 25 35 50 60 Ce Recovery (%) 92.7 84.9 82.2 81.8 Ce grade 91.2 97.3 99.8 99.7

Cerium complex anion-containing solution in which trivalent rare earth elements were separated and removed by sodium sulfate double-precipitation, and the composition is shown in Table 4. The content of cerium in rare earth elements was 99.8%, indicating that high purity separation was achieved.

Composition of solution after removal of trivalent rare earth ions Element Ce La Pr Nd Content 2.92% 81 ppm <1 ppm 10 ppm

In addition, a method of preparing cerium hydroxide from the cerium sulphate anion-containing solution will be described in detail with reference to Examples.

Example 2

Removal of Fluoride in Cerium Hydroxide Preparation from Cerium Fluoride Anion-Containing Solution

The cerium fluoride anion containing cerium fluoride anion is separated from cerium fluoride and fluorine, and then an intermediate product is formed to solid-separate it. Cerium hydroxide is prepared by successively adding the intermediate to an aqueous sodium hydroxide solution.

Generally, trivalent rare earth ions react with fluorine to form white fluoride rare earths. Therefore, by adding hydrogen peroxide, a reducing agent, to a solution containing cerium fluoride anion, cerium fluoride is formed as shown in the following formula, and the cerium fluoride has an average particle size of about 2 μm, which has a low conversion rate when preparing cerium hydroxide as a raw material, and also produces cerium hydroxide. After washing with water, it is difficult to remove reaction byproducts such as NaF.

Cerium hydroxide from cerium fluoride is prepared by Schemes 3 and 4.

^{_{[CeF 6] 2- + 1 /}} 2H 2 O 2 → CeF 3 ↓ + HF + 2F -

CeF ₃ + ₃ NaOH → Ce (OH) ₃ ↓ + 3NaF

In addition, sodium peroxide is added to the cerium fluoride anion solution, and then hydrogen peroxide is formed, and sodium cerium sulfate is formed. When cerium hydroxide is prepared as a raw material, the size of the particles increases, so that the reaction by-products are easily removed when washing with water. The conversion also takes place quickly.

Cerium hydroxide is calculated | required from Reaction Formula 5, 6 from sodium cerium sulfate.

^{_{[CeF 6] 2- + 1 /}} 2H 2 O 2 + 2Na 2 SO 4 → CeNa (SO 4) 2 ↓ + 1 / 2O 2 ↑ + 3NaF + HF + 2F -

CeNa (SO ₄ ) ₂ + ₃ NaOH → Ce (OH) ₃ ↓ + 2Na ₂ SO ₄

XRD diffraction analysis results of sodium cerium sulfate formed after hydrogen peroxide addition while changing the amount of sodium sulfate added to the cerium fluoride anion-containing solution prepared by the above reaction scheme are shown in FIG. It can be seen that formed.

However, as shown in FIG. 3, the particles present in the particle size distribution of the sodium cerium sulfate near 1 μm are cerium fluoride, and thus, some cerium fluoride may be produced during the production of sodium cerium sulfate.

The cerium hydroxide is prepared by adding sodium cerium sulfate to an aqueous sodium hydroxide solution, and as shown in FIG. 4, after preparing cerium hydroxide from sodium cerium sulfate, calcining at 900 ° C., converting to cerium oxide, and performing XRD diffraction analysis. For example, 34-394 is the reference peak of cerium oxide and 8-45 is the reference peak of cerium fluoride.

Therefore, when aluminum sulfate is added to the solution for the removal of fluorine, hydrogen peroxide solution is added, a reaction as in Scheme 7 occurs.

[CeF ₆ ] ^2- + 1 / 2H ₂ O ₂ + 2Na ₂ SO ₄ + 1 / 2Al _{2 (} SO ₄ ) ₃ → CeNa (SO ₄ ) ₂ ↓ + 1 / 2O ₂ + H ⁺ + 3 / 2Na ₂ SO ₄ + [AlF ₆ ] ^-3

According to Reaction Formula 7, the fluorine present in the solution was able to inhibit the precipitation to cerium fluoride by forming aluminum fluoride anion in combination with the aluminum ion.

In addition, the experimental results according to the change in the amount of aluminum sulfate added to remove the fluorine component is shown in Table 5. To completely remove the fluorine component, about 2.5 equivalents of aluminum sulfate are required, and the reaction temperature is about 50 ° C. or more. It was found that a reaction of 2 hours was required.

Analysis of fluorine in sodium cerium sulfate using PIGE Sample name Manufacture conditions F (%) CeF ₃ Cerium fluoride production by H ₂ O ₂ addition 27.0 CNS Na ₂ SO ₄ and H ₂ O ₂ addition (temperature 35 ° C) 5.4 CNS Na ₂ SO ₄ and H ₂ O ₂ addition (temperature 45 ° C) 5.8 CNS (Al) Na ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and H ₂ O ₂ added (temperature 45 ° C) 0.054 CNS (Al) Na ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and H ₂ O ₂ added (temperature 50 ° C) 0.032 CNS (Al) Na ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and H ₂ O ₂ added (temperature 60 ° C) 0.025

Cerium hydroxide prepared from the fluorine-free sodium cerium sulfate compound as described above is a result of XRD diffraction analysis of cerium oxide obtained by calcining at 900 ° C as shown in FIG. It was found that no fluorine was present in the cerium hydroxide.

As described above, the present invention provides a high-purity cerium hydroxide used as a raw material for cerium compounds suitable for various purposes by separating cerium in a mixed rare earth solution using sodium sulfate and removing fluorine from the separated and recovered cerium fluoride solution. It is easy to manufacture.

In addition, it solves environmental problems such as air pollution due to the release of fluorine and sulfurous acid gas during sulphation decomposition, and solves problems such as low recovery rate and low quality when separating and recovering cerium from rare earth elements.

In addition, fluorine is simultaneously removed from the separated and recovered cerium solution.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as provided by the following claims. I would like to clarify that those who have knowledge of this can easily know.

Claims (5)

In the method for producing high purity cerium hydroxide from fluorocarbonate rare earth concentrate, Drying and crushing the carbonate rare earth light; Oxidizing and roasting the crushed fluorate rare earth ore to leach sulfuric acid; Separating and recovering cerium by adding sodium sulfate to the sulfuric acid leaching solution; Adding sodium sulfate and aluminum sulfate to a separation and recovery solution containing cerium fluoride anion to remove precipitates of sodium cerium sulfate and fluorine; and A method of producing cerium hydroxide from which fluorine is removed from a fluoride rare earth concentrate comprising the step of adding an aqueous sodium hydroxide solution to sodium cerium sulfate. The method of claim 1, wherein the separating and recovering cerium by adding sodium sulfate selectively reacts trivalent rare earth elements other than tetravalent cerium with sodium sulfate, and the TREO concentration of the leaching solution is 50 to 100 g / L , A method for producing cerium hydroxide from which fluorine is removed from a fluoride rare earth concentrate, wherein the amount of sodium sulfate added is 1.5 to 2.5 equivalents and the reaction temperature is 30 to 60 ° C. The method of claim 1, wherein the adding of sodium hydroxide aqueous solution to the sodium cerium sulfate has a purity of 99% or more of cerium hydroxide. The method of claim 1, wherein the amount of sodium sulfate added in the preparation of sodium cerium sulfate using sodium sulfate is 2 equivalents. The method of claim 1, wherein the amount of aluminum sulfate added to the cerium fluoride anion-containing solution is 1.5 to 3.0 equivalents, the reaction temperature is 30 to 60 DEG C, and the reaction time is 1 to 3 hours. A method of producing cerium hydroxide from which fluorine is removed from a fluorocarbonate rare earth concentrate.