CN110484754B

CN110484754B - Method for removing sulfate radical in rare earth precipitate and product obtained by method

Info

Publication number: CN110484754B
Application number: CN201910922034.9A
Authority: CN
Inventors: 付国燕; 王玮玮; 姚心; 吕东
Original assignee: China ENFI Engineering Corp
Current assignee: China ENFI Engineering Corp
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2021-08-10
Anticipated expiration: 2039-09-27
Also published as: CN110484754A

Abstract

Disclosed is a method for removing sulfate radicals from rare earth precipitates, comprising: a solution forming step, namely preparing the pretreated rare earth precipitate into a solution containing sulfate ions and rare earth ions; a precipitation step, adding oxalate as a precipitator into the solution for precipitation reaction to obtain a precipitate; and a purification step of dissolving the precipitate with hydrochloric acid and then performing secondary precipitation with hydroxide as a precipitant. The method of the invention effectively improves the purity of the rare earth oxide; the process flow of purifying the rare earth precipitate is simplified; the energy consumption is reduced; the generation of waste residue and solid waste is avoided.

Description

Method for removing sulfate radical in rare earth precipitate and product obtained by method

Technical Field

The invention relates to the field of hydrometallurgy, in particular to a method for removing sulfate radicals in rare earth precipitates and a product obtained by the method.

Background

The precipitation is an essential separation and purification method in the production of the metallurgical industry, and practically almost all hydrometallurgy processes have precipitation procedures, so that the method has the characteristics of simple operation, low cost, low investment and the like. Precipitation is a method of separating a solute in a solution after supersaturation of the solute and precipitation in a solid form by appropriate measures. It has two main ways: (1) removing impurities from the solution, separating the impurities from the solution, the primary metal remaining in the solution; (2) pure compounds of the principal metals precipitate out of solution, leaving impurities in solution. With the continuous improvement of the requirement on the product quality, the requirement on the impurity content in the precipitate is also continuously improved, sulfuric acid is commonly used for leaching and extraction reaction in the process of extracting rare earth elements, a large amount of sulfate ions are introduced into a reaction system, and after the precipitation process, sulfate radicals, corresponding rare earth elements and a precipitator form double salts, so that the purity of the rare earth precipitate is seriously influenced.

The rare earth precipitate prepared at present contains a large amount of sulfate ions, so that the purity of rare earth substances is seriously reduced, and the quality of the rare earth substances is influenced. In order to remove sulfate radicals in rare earth materials, barium chloride is adopted by various rare earth plants to remove sulfate radicals in the rare earth materials, which causes certain problems. Firstly, the toxic and harmful substance barium chloride is introduced into the sediment, and secondly, a large amount of secondary waste residue barium sulfate is generated. Meanwhile, the roasting temperature needs to be increased in order to improve the purity of the rare earth precipitate, so that the energy consumption for preparing the rare earth substance is increased, and the effective utilization and development of the rare earth substance are seriously restricted.

Disclosure of Invention

In order to overcome the defects, the invention provides a method for removing sulfate radicals in rare earth precipitates and a product prepared by the method.

The invention provides a method for removing sulfate radicals in rare earth precipitates, which comprises the following steps: a solution forming step, namely preparing the pretreated rare earth precipitate into a solution containing sulfate ions and rare earth ions; a precipitation step, adding oxalate as a precipitator into the solution for precipitation reaction to obtain a precipitate; and a purification step of dissolving the precipitate with hydrochloric acid and then performing secondary precipitation with hydroxide as a precipitant.

According to an embodiment of the present invention, in the step of forming the solution, the sulfate ion concentration in the solution is 0.50 to 1.5mol/l, and preferably 0.75 to 1.5 mol/l.

According to another embodiment of the present invention, in the precipitation step, before adding the precipitant, further comprising: heating the solution to 70-100 ℃, preferably 75-95 ℃; and adding a dispersant to the solution.

According to another embodiment of the present invention, in the precipitation step, the rare earth ions are precipitated in a molar ratio of rare earth ions to oxalate of 1: 1-1: 5, adding a precipitator into the solution, and simultaneously adding a pH value regulator to maintain the pH value of the reaction system between 1.0 and 3.0, preferably between 1.5 and 3; stirring is kept, and the stirring speed is 100-300 r/min, preferably 100-200 r/min; and (3) continuously stirring after the precipitant is added, wherein the stirring speed is 50-200 r/min, preferably 100-150 r/min, and the stirring time is 15-90 min, preferably 30-90 min.

According to another embodiment of the present invention, the method further comprises a first aging step after the precipitation step, wherein the aging temperature is 70 to 100 ℃, preferably 75 to 95 ℃; the aging time is 30-200 min, preferably 60-180 min.

According to another embodiment of the present invention, in the purification step, the rare earth ions are mixed in a molar ratio of 1: 1.5-1: 4, adding hydrochloric acid for dissolution, preferably 1: 2-1: 3; the heating temperature is 20-70 ℃, and preferably 30-50 ℃; the stirring speed is 100-300 r/min, preferably 100-200 r/min; the stirring time is 15-90 min, preferably 30-90 min.

According to another embodiment of the present invention, in the purification step, the rare earth ions are mixed in a molar ratio of 1: 2-1: 4 adding hydroxide.

According to another embodiment of the present invention, after the purification step, a second aging step is further included, wherein the aging temperature is 70 to 100 ℃, preferably 75 to 95 ℃; the aging time is 30-200 min, preferably 60-180 min.

According to another embodiment of the invention, the roasting temperature is 700-1100 ℃, preferably 800-1000 ℃; the roasting time is 100-400 min, preferably 120-300 min.

The invention also provides a rare earth oxide product prepared by the purification method.

The method of the invention uses oxalate as a rare earth precipitator to precipitate the rare earth-containing solution, and the rare earth-containing precipitate is obtained after filtration treatment; adding a certain amount of hydrochloric acid into the rare earth precipitate to dissolve the rare earth precipitate to form rare earth chloride, performing secondary precipitation reaction by using a hydroxide precipitator, filtering to obtain rare earth precipitate, and roasting to obtain pure rare earth oxide. The method of the invention effectively improves the purity of the rare earth oxide; the process flow of purifying the rare earth precipitate is simplified; the energy consumption is reduced; the generation of waste residue and solid waste is avoided.

Drawings

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

FIG. 1 is a schematic flow diagram of the process of the present invention.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

As shown in FIG. 1, the method for removing sulfate radicals from rare earth precipitates of the present invention comprises: s1, a solution forming step, namely preparing the pretreated rare earth precipitate into a solution containing sulfate ions and rare earth ions; s2 precipitation step, adding oxalate as a precipitator into the solution for precipitation reaction to obtain a precipitate; and S3 purification step, dissolving the precipitate with hydrochloric acid, and then carrying out secondary precipitation by using hydroxide as a precipitator.

The "pretreated rare earth precipitate" described in this patent refers to a solid substance comprising sulfate and rare earth elements.

In step S1, the sulfate ion concentration in the solution is 0.50-1.5 mol/l, preferably 0.75-1.5 mol/l.

In step S2, the solution may be heated to raise the reaction temperature before adding the precipitant in order to accelerate the reaction. The temperature of the solution is preferably maintained at 70 to 100 ℃, more preferably 75 to 95 ℃. In order to increase the dispersibility of the precipitate, an ammonium salt dispersant can be added, and the pH value of the system is kept between 1.0 and 3.0. And then, mixing rare earth ions and oxalate in a molar ratio of 1: 1-1: 5 oxalate precipitating agent is added to the solution. Meanwhile, the alkaline pH value regulator is continuously added to maintain the pH value of the reaction system between 1.0 and 3.0, preferably between 1.5 and 3. And stirring is kept, and the stirring speed is 100-300 r/min, preferably 100-200 r/min. And (3) continuously stirring after the precipitant is added, wherein the stirring speed is 50-200 r/min, preferably 100-150 r/min, and the stirring time is 15-90 min, preferably 30-90 min.

The method also comprises a first aging step after the step of S2, wherein the aging temperature is 70-100 ℃, and preferably 75-95 ℃; the aging time is 30-200 min, preferably 60-180 min.

Then filtering the solution obtained after aging to obtain a precipitate. The precipitate may be repeatedly washed several times using water and ethanol, respectively, to remove impurities. Subsequently, in step S3, the precipitate after filtration is treated with a hydrochloric acid solution. The molar ratio of the rare earth ions to the hydrochloric acid is 1: 1.5-1: 4, preferably 1: 2-1: 3, adding hydrochloric acid to dissolve. In order to accelerate the reaction, the system may be heated to a temperature of 20 to 70 ℃, preferably 30 to 50 ℃. Meanwhile, the system can be stirred at a stirring speed of 100-300 r/min, preferably 100-200 r/min. The stirring time is 15-90 min, preferably 30-90 min.

After the hydrochloric acid and the precipitate have reacted, hydroxide, such as sodium hydroxide, potassium hydroxide, ammonia water, etc., is added to the system to perform secondary precipitation. And the molar ratio of the rare earth ions to the hydroxide is 1: 2-1: 4 ratio of hydroxide.

After the secondary precipitation, a second aging step is also included, wherein the aging temperature is 70-100 ℃, and preferably 75-95 ℃. The aging time is 30-200 min, preferably 60-180 min.

Then filtering the solution obtained after aging to obtain a precipitate. The precipitate may be repeatedly washed several times using water and ethanol, respectively, to remove impurities. And drying the precipitate at the temperature of 70-120 ℃ to obtain a pure rare earth precipitate powder material.

And roasting the rare earth precipitate powder material, for example, roasting in a muffle furnace at 700-1100 ℃, preferably for 100-400 min, and then cooling the sample to normal temperature along with the furnace to obtain a relatively pure rare earth oxide powder material.

Example 1

And preparing the pretreated rare earth precipitate into a rare earth-containing solution with the sulfate radical content of 0.75 mol/l. Adding a certain amount of ammonium sulfate dispersant at the temperature of 80 ℃, and stirring at the speed of 100r/min according to the molar ratio of the rare earth ions to the precipitator of 1: 2, continuously adding oxalate precipitator into the reactor, and continuously using ammonium salt to adjust the pH value of the system during the period so as to maintain the pH value of the reaction system at about 1.5. After the precipitant is added, the final pH value of the system is ensured to be about 1.5, then the system is continuously stirred for 30min at the stirring speed of 100r/min, and after the reaction is finished, the system is aged and reacted for 60min at the temperature of 80 ℃. The obtained precipitate system was subjected to suction filtration during which 3 and 5 washes with water and ethanol, respectively, were carried out. Dissolving a rare earth precipitate sample by using a certain amount of hydrochloric acid, placing the rare earth precipitate in a precipitation reactor, and adding 100ml of purified water to dilute the mother liquor containing the rare earth chloride. Under the conditions of 80 ℃, normal pressure and 100r/min of stirring, adding a certain amount of ammonia water precipitator into the precipitation reactor, so that the ratio of the original rare earth ion concentration to the hydroxide concentration is 1: 2. after the hydroxide precipitant is added, the mixture is continuously stirred for 30min at the stirring speed of 100r/min, and is aged and reacted for 60min at the temperature of 80 ℃. And carrying out suction filtration treatment on the obtained solution system containing the rare earth precipitate sample, respectively washing 3 and 5 times by using water and ethanol in the process, placing the obtained sample in a drying box, and drying for 300min at the temperature of 100 ℃. And placing the dried sample in a corundum crucible, roasting the sample in a muffle furnace at 800 ℃ for 300min, and then cooling the sample to normal temperature along with the furnace, wherein the sulfur content is about 1.93%.

Example 2

The pretreated rare earth precipitate is prepared into a rare earth-containing solution with the sulfate radical content of 1.5 mol/l. Adding a certain amount of ammonium sulfate dispersant at the temperature of 95 ℃, and stirring at the speed of 200r/min according to the molar ratio of the rare earth ions to the precipitant of 1: 2, continuously adding oxalate precipitator into the reactor, and continuously using ammonium salt to adjust the pH value of the system during the period so as to maintain the pH value of the reaction system at about 3. After the precipitant is added, the final pH value of the system is ensured to be about 3, then the system is continuously stirred for 90min at the stirring speed of 100r/min, and after the reaction is finished, the system is aged and reacted for 180min at the temperature of 95 ℃. The obtained precipitate system was subjected to suction filtration during which 3 and 5 washes with water and ethanol, respectively, were carried out. Dissolving a rare earth precipitate sample by using a certain amount of hydrochloric acid, placing the rare earth precipitate in a precipitation reactor, and adding 100ml of purified water to dilute the mother liquor containing the rare earth chloride. Under the conditions of 90 ℃, normal pressure and 200r/min of stirring, adding a certain amount of ammonia water precipitator into the precipitation reactor, so that the ratio of the original rare earth ion concentration to the hydroxide concentration is 1: 4. after the hydroxide precipitant is added, the mixture is continuously stirred for 90min at the stirring speed of 100r/min and is aged and reacted for 180min at the temperature of 95 ℃. And carrying out suction filtration treatment on the obtained solution system containing the rare earth precipitate sample, respectively washing 3 and 5 times by using water and ethanol, placing the obtained sample in a drying box, and drying for 300min at the temperature of 110 ℃. And placing the dried sample in a corundum crucible, roasting the sample in a muffle furnace at 900 ℃ for 200min, and then cooling the sample to normal temperature along with the furnace, wherein the sulfur content is about 0.56%.

Example 3

And preparing the pretreated rare earth precipitate into a rare earth-containing solution with the sulfate radical content of 1.0 mol/l. Adding a certain amount of ammonium sulfate dispersant at 75 ℃, and stirring at 200r/min according to the molar ratio of the rare earth ions to the precipitant of 1: 2, continuously adding oxalate precipitator into the reactor, and continuously using ammonium salt to adjust the pH value of the system during the period so as to maintain the pH value of the reaction system at about 2. After the precipitant is added, the final pH value of the system is ensured to be about 2, then the system is continuously stirred for 90min at the stirring speed of 100r/min, and after the reaction is finished, the system is aged and reacted for 90min at the temperature of 75 ℃. The obtained precipitate system was subjected to suction filtration during which 3 and 5 washes with water and ethanol, respectively, were carried out. Dissolving a rare earth precipitate sample by using a certain amount of hydrochloric acid, placing the rare earth precipitate in a precipitation reactor, and adding 100ml of purified water to dilute the mother liquor containing the rare earth chloride. Under the conditions of 90 ℃, normal pressure and 200r/min of stirring, adding a certain amount of dilute sodium hydroxide precipitator solution into a precipitation reactor to ensure that the ratio of the original rare earth ion concentration to the hydroxide concentration is 1: 3. after the precipitant is added, the mixture is continuously stirred for 90min at the stirring speed of 100r/min and is aged and reacted for 90min at the temperature of 75 ℃. And carrying out suction filtration treatment on the obtained solution system containing the rare earth precipitate sample, respectively washing 3 and 5 times by using water and ethanol, placing the obtained sample in a drying box, and drying for 420min at the temperature of 100 ℃. And placing the dried sample in a corundum crucible, roasting the sample in a muffle furnace at 1000 ℃ for 120min, and then cooling the sample to the normal temperature along with the furnace, wherein the sulfur content is about 0.97%.

Comparative example 1

Taking a rare earth solution with the sulfate radical content of 0.75mol/l, adding a certain amount of ammonium sulfate dispersant at the temperature of 80 ℃, and stirring at the speed of 100r/min according to the molar ratio of rare earth ions to a precipitator of 1: 2, continuously adding oxalate precipitator into the reactor, and continuously using ammonium salt to adjust the pH value of the system during the period so as to maintain the pH value of the reaction system at about 1.5. After the precipitant is added, the final pH value of the system is ensured to be about 2, then the system is continuously stirred for 30min at the stirring speed of 100r/min, and after the reaction is finished, the aging reaction is carried out for 60min under the temperature condition of 80 ℃. The obtained precipitate system was subjected to suction filtration during which 3 and 5 washes with water and ethanol, respectively, were carried out. The obtained sample is placed in a drying oven and dried for 420min at 80 ℃. And placing the dried sample in a corundum crucible, roasting the sample in a muffle furnace at 800 ℃ for 300min, and then cooling the sample to normal temperature along with the furnace, wherein the sulfur content is about 5.33%.

Comparing the results of examples 1-3 with comparative example 1, it can be seen that the method of the present invention can significantly reduce the sulfate content in the pretreated rare earth precipitate, and improve the purity of the rare earth oxide product.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method of removing sulfate radicals from rare earth precipitates comprising:

a solution forming step, namely preparing the pretreated rare earth precipitate into a solution containing sulfate ions and rare earth ions, wherein the concentration of the sulfate ions in the solution is 0.50-1.5 mol/l;

a precipitation step, adding oxalate as a precipitator into the solution for precipitation reaction to obtain a precipitate; the molar ratio of rare earth ions to oxalate is 1: 1-1: 5, adding a precipitator into the solution, and simultaneously adding a pH value regulator to maintain the pH value of the reaction system between 1.0 and 3.0; stirring is kept, and the stirring speed is 100-300 r/min; after the precipitator is added, continuously stirring at the speed of 50-200 r/min for 15-90 min; in the precipitation step, before adding the precipitant, the method further comprises:

heating the solution to 70-100 ℃; and

adding a dispersant to the solution;

a first aging step, wherein aging is carried out after the precipitation step, and the aging temperature is 70-100 ℃; the aging time is 30-200 min;

and a purification step, dissolving the precipitate with hydrochloric acid, and then performing secondary precipitation by using hydroxide as a precipitating agent, wherein the molar ratio of the rare earth ions to the hydrochloric acid is 1: 1.5-1: 4, adding hydrochloric acid for dissolving; the heating temperature is 20-70 ℃; the stirring speed is 100-300 r/min; stirring for 15-90 min; and the molar ratio of the rare earth ions to the hydroxide is 1: 2-1: 4 adding hydroxide; and

a second aging step, wherein aging is carried out after the purification step, and the aging temperature is 70-100 ℃; the aging time is 30-200 min.

2. The method of claim 1, wherein in the step of forming the solution, the sulfate ion concentration in the solution is 0.75 to 1.5 mol/l.

3. The method of claim 1, wherein in the precipitating step, prior to adding the precipitating agent, further comprising:

heating the solution to 75-95 ℃.

4. The method according to claim 1, characterized in that, in the precipitation step, the molar ratio of rare earth ions to oxalate is 1: 1-1: 5, adding a precipitator into the solution, and simultaneously adding a pH value regulator to maintain the pH value of the reaction system between 1.5 and 3.0; stirring is kept, and the stirring speed is 100-200 r/min; and (3) continuously stirring after the precipitant is added, wherein the stirring speed is 100-150 r/min, and the stirring time is 30-90 min.

5. The method according to claim 1, further comprising a first aging step after the precipitation step, wherein the aging temperature is 75-95 ℃; the aging time is 60-180 min.

6. The method according to claim 1, wherein, in the purification step, the rare earth ions and the hydrochloric acid are mixed in a molar ratio of 1: 2-1: 3, adding hydrochloric acid for dissolving; the heating temperature is 30-50 ℃; the stirring speed is 100-200 r/min; the stirring time is 30-90 min.

7. The method according to claim 1, further comprising a second aging step after the purification step, wherein the aging temperature is 75-95 ℃; the aging time is 60-180 min.

8. The method according to claim 1, further comprising a roasting step of roasting the rare earth precipitate after the secondary precipitation, wherein the roasting temperature is 700-1100 ℃; the roasting time is 100-400 min.

9. The method according to claim 8, further comprising a roasting step of roasting the rare earth precipitate after the secondary precipitation, wherein the roasting temperature is 800-1000 ℃; the roasting time is 120-300 min.

10. A rare earth hydroxide product obtainable by the process of any one of claims 1 to 7.

11. A rare earth oxide product produced by the method of claim 8 or 9.