Rare earth ore leaching impurity removal process and split type impurity removal tank

Abstract

The invention relates to the technical field of rare earth impurity removal, and discloses a rare earth ore leaching impurity removal process and a split type impurity removal tank, the rare earth ore leaching impurity removal process comprises the following steps: step 1, dissolving rare earth raw ore: dissolving a rare earth raw ore mixture with hydrochloric acid; and step 2, sulfate radical removal: adding barium salt to remove sulfate radicals, and filtering sand insoluble particles and barium sulfate through a filter press to obtain rare earth feed liquid. The invention provides a split type impurity removal tank process, by adopting the split type impurity removal tank technology, the rare earth recovery efficiency is improved, meanwhile, the rare earth recovery cost is reduced, according to the technology, the high yield with the daily treatment capacity exceeding 10 tons is achieved by using a split type extraction impurity removal tank transformed from a saponification barrel with the volume of 4 m < 3 >, the treatment capacity is remarkably improved, and the energy consumption is reduced. Compared with a traditional impurity removal process, the improvement not only reduces material investment, but also effectively removes iron and aluminum impurities in the rare earth feed liquid through more uniform stirring and higher impurity removal efficiency, so that the recovery cost of rare earth is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth impurity removal, and more specifically, to a rare earth ore leaching impurity removal process and a split-type impurity removal tank. Background Art

[0002] Southern rare earth mainly consists of ion-adsorption type ores, and rare earth elements are adsorbed in an ionic state on the surface of clay minerals. When leaching ionic rare earth ores, a large amount of aluminum ions present in the clay minerals enter the leaching solution along with the rare earth. Aluminum ions are prone to hydrolysis in the feed liquid, forming flocculent and adhesive precipitates, which not only increase the difficulty of subsequent separation processes, but also reduce the organic phase loading capacity, resulting in a significant decrease in extraction efficiency, and ultimately leading to the serious consequence that rare earth is difficult to separate and purify. In addition, since an alkali needs to be added in the extraction section to adjust the acidity of the tank body, if there are too many aluminum impurity ions, colloidal precipitates will be formed in the form of hydroxides, causing emulsification of the extraction tank and affecting the normal operation of the entire production line. Therefore, it is necessary to develop an effective method for removing aluminum impurities based on the existing impurity removal process. Summary of the Invention

[0003] The present invention provides a rare earth ore leaching impurity removal process and a split-type impurity removal tank, and solves the technical problem that there are too many residual aluminum impurity ions during impurity removal in the related art, forming colloidal precipitates in the form of hydroxides, causing emulsification of the extraction tank and affecting the normal operation of the entire production line.

[0004] The present invention provides a rare earth ore leaching impurity removal process, including the following steps:

[0005] Step 1, dissolution of rare earth raw ore: The rare earth raw ore mixture is dissolved with hydrochloric acid;

[0006] Step 2, removal of sulfate radical: A barium salt is added to remove the sulfate radical, and the sand and insoluble particles and barium sulfate are filtered through a pressure filter to obtain a rare earth feed liquid;

[0007] Step 3, removal of iron ions: The above rare earth feed liquid enters the impurity removal tank, and N-235 is first used to remove iron ions, controlling the Fe 3+ concentration to be less than 0.1 mg / L;

[0008] Step 4, removal of aluminum ions: The above feed liquid enters the split-type impurity removal tank to remove aluminum ions, controlling the Al 3+ concentration to be less than 100 mg / L;

[0009] Step 5, separation by the extraction production line: The above feed liquid enters the extraction production line for separation to become single rare earth;

[0010] Step 6, precipitation and calcination: Through precipitation and calcination, it becomes rare earth oxide;

[0011] In the step 4, the mixing and clarifying of the feed liquid are carried out separately, and the alkali solution is added while stirring during the mixing process, and the pH is adjusted to 4.0-4.5, the stirring speed of the feed liquid is controlled to 200-300 rpm, and the reaction time is controlled to 15-20 min;

[0012] Static sedimentation is used for clarification, and the sedimentation time is controlled to be 30 to 60 minutes. The upper clear liquid in the clarification interface overflows in sequence until it enters the next process, and the lower precipitate is concentrated and discharged into the filter press for recovery.

[0013] As a further solution of the present invention: the addition of alkali solution in the mixing process is divided into three stages:

[0014] Initial stage: add 40% of the total amount of alkali solution and adjust the pH to 3.0-3.5;

[0015] Mid-stage: add 30% and slowly raise the pH to 4.0-4.2;

[0016] Final stage: add the remaining 30% and fine-tune to the target pH 4.5;

[0017] Each addition was done at an interval of 2 to 3 minutes, and the pH value was adjusted dynamically in conjunction with online pH monitoring.

[0018] As a further solution of the present invention: the rare earth ore dissolution comprises the following steps:

[0019] a. Prepare rare earth ore: pre-treat the rare earth ore, including crushing and screening, to increase the contact area between the ore and the acid;

[0020] b. Hydrochloric acid dissolution: Mix the pretreated rare earth ore with hydrochloric acid, and control the temperature and time to fully dissolve the rare earth elements;

[0021] c. Solution collection: Collect the dissolved solution and prepare for the next step of impurity removal.

[0022] As a further solution of the present invention: the sulfate removal comprises the following steps:

[0023] a. Addition of barium salt: Add an appropriate amount of barium salt to the rare earth solution to react with sulfate to form insoluble barium sulfate;

[0024] b. Mixing reaction: fully stir the rare earth solution to ensure that the barium salt and sulfate react completely;

[0025] c. Filter press filtration: Use a filter press to filter out insoluble particles and generated barium sulfate to obtain pure rare earth liquid.

[0026] As a further solution of the present invention: Step 2, Step 3 and Step 4 are all equipped with emission treatment, and the emission treatment includes the following steps:

[0027] a. Open the discharge port: Open the reserved outlet of the split impurity removal tank.

[0028] b. Three-phase discharge: Discharge the three-phase mixture, including solid precipitate, liquid feed liquid, and supernatant.

[0029] c. Clean the tank body: After the discharge is completed, clean the tank body to prepare for the next operation.

[0030] As a further solution of the present invention: The separation of the extraction production line includes the following steps:

[0031] a. Feed liquid transfer: Transfer the treated feed liquid to the extraction production line.

[0032] b. Extraction operation: Separate rare earth elements through an extraction tower, utilizing the extraction characteristics of different rare earth elements.

[0033] c. Single rare earth collection: Collect the separated single rare earth solution and prepare for the next precipitation and calcination.

[0034] The split impurity removal tank, applied to the above-mentioned rare earth ore leaching and impurity removal process, includes several mixing tanks and clarification tanks, which are connected by pipelines to form a pre-stage A, an intermediate stage B, and a post-stage C that are sequentially connected. The pre-stage A contains two mixing tanks and two clarification tanks, which are connected in parallel by pipelines. The intermediate stage B contains three mixing tanks connected in series by pipelines. The post-stage C contains two mixing tanks and five clarification tanks, which are connected in series by pipelines.

[0035] As a further solution of the present invention: The pre-stage A is used to complete the removal of iron ions, and the operation steps include:

[0036] a. Clean the mixing tank and clarification tank to ensure no impurities.

[0037] b. Stir and mix the rare earth feed liquid and N-235 in the first mixing tank, and control the Fe3+ concentration to be less than 0.1 mg / L.

[0038] c. After sufficient mixing, transfer the feed liquid to the first clarification tank for preliminary sedimentation, and then transfer the obtained feed liquid to the second mixing tank, add water for dilution and stir again.

[0039] d. Transfer the obtained feed liquid to the second clarification tank for further sedimentation until iron ions are fully removed.

[0040] As a further solution of the present invention: The intermediate stage B is used for the addition and mixing of lye, and the mixing tanks connected in series included correspond one-to-one to the initial stage, the intermediate stage, and the final stage of lye addition.

[0041] As a further solution of the present invention: an outlet is reserved at the middle of the mixing tank for discharging the three phases, without opening the tank cover plate to dig the three phases.

[0042] The beneficial effects of the present invention are as follows:

[0043] In view of the fact that excessive iron and aluminum impurities will cause emulsification during rare earth extraction and separation, resulting in losses of the organic phase and rare earths, and in severe cases, clogging the tank body and hindering the normal extraction process, which has a great impact on the rare earth separation process. The present invention applies a split-type impurity removal tank to completely separate the stirring link and the clarification link, extend the clarification time, slowly and dispersedly add liquid caustic soda, improve the primary yield while reducing the recovery costs of impurities and rare earths. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic diagram of the overall process flow of the rare earth ore leaching and impurity removal process proposed by the present invention;

[0045] Figure 2 is a schematic diagram of the dispersed layout of the split-type impurity removal tank proposed by the present invention;

[0046] Figure 3 is a schematic diagram of the combined layout of the split-type impurity removal tank proposed by the present invention;

[0047] Figure 4 is a schematic diagram of the structure of the mixing tank proposed by the present invention.

[0048] In the figure:

[0049] 10. Mixing tank; 100. Outlet; 20. Clarification tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] Now, the subject matter described herein will be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the scope of protection of the content of this specification, changes can be made to the functions and arrangements of the elements discussed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0051] As Figure 1 - Figure 4 shown, the rare earth ore leaching and impurity removal process includes the following steps:

[0052] Step 1. Dissolution of rare earth raw ore: The rare earth raw ore mixture is dissolved with hydrochloric acid;

[0053] Step 2. Removal of sulfate radicals: Add barium salt to remove sulfate radicals, and filter the sand and insoluble particles and barium sulfate through a pressure filter to obtain rare earth liquor;

[0054] Step 3. Removal of iron ions: The above-mentioned rare earth liquor enters the impurity removal tank, and N-235 is first used to remove iron ions, controlling the Fe 3+ concentration to be less than 0.1 mg / L;

[0055] Step 4. Removal of aluminum ions: The above-mentioned liquor enters the split-type impurity removal tank to remove aluminum ions, controlling the Al 3+ concentration to be less than 100 mg / L;

[0056] Step 5. Separation by the extraction production line: The above-mentioned liquor enters the extraction production line for separation to become single rare earths;

[0057] Step 6. Precipitation and calcination: Through precipitation and calcination, rare earth oxides are obtained;

[0058] In the above Step 4, the mixing and clarification of the liquor are carried out separately. During the mixing process, caustic liquor is dispersed and added while stirring, adjusting the pH to 4.0 - 4.5. The stirring speed of the liquor is controlled at 200 - 300 rpm, and the reaction time is controlled at 15 - 20 min;

[0059] The clarification is carried out by static sedimentation. The sedimentation time is controlled at 30 - 60 min. The supernatant liquid in the upper layer of the clarification interface overflows in sequence until it enters the next process, and the lower layer of sediment is concentrated and discharged into the filter press for recovery.

[0060] In the above mixing process, the addition of caustic liquor is divided into three stages:

[0061] Initial stage: Add 40% of the total amount of caustic liquor to adjust the pH to 3.0 - 3.5;

[0062] Middle stage: Add 30%, slowly raise the pH to 4.0 - 4.2;

[0063] Final stage: Add the remaining 30% and finely adjust to the target pH of 4.5;

[0064] The interval between each addition is 2 - 3 minutes, and it is dynamically adjusted in cooperation with on-line pH monitoring.

[0065] Excessive iron and aluminum impurities will cause emulsification during the extraction and separation of rare earths, resulting in losses of the organic phase and rare earths. In severe cases, it will block the tank body, hinder the normal extraction process, and have a great impact on the rare earth separation process. The present invention uses a split-type impurity removal tank to completely separate the stirring link and the clarification link, extend the clarification time, slowly and dispersedly add liquid caustic, improve the primary yield, and reduce the recovery costs of impurities and rare earths.

[0066] The dissolution of the rare earth raw ore includes the following steps:

[0067] a. Preparation of rare earth raw ore: The rare earth raw ore is pretreated, including crushing and screening, to increase the contact area between the ore and the acid;

[0068] b. Dissolution with hydrochloric acid: Mix the pretreated rare earth raw ore with hydrochloric acid, control the temperature and time to fully dissolve the rare earth elements;

[0069] c. Solution collection: Collect the dissolved solution and prepare for the next impurity removal treatment.

[0070] The removal of sulfate radicals includes the following steps:

[0071] a. Addition of barium salt: Add an appropriate amount of barium salt to the rare earth feed liquid to react with sulfate radicals to form insoluble barium sulfate;

[0072] b. Mixing reaction: Stir the rare earth feed liquid thoroughly to ensure complete reaction between the barium salt and sulfate radicals;

[0073] c. Pressure filtration: Use a pressure filter to filter out the insoluble particles and the generated barium sulfate to obtain a pure rare earth feed liquid.

[0074] In steps two, three, and four, emission treatment is configured, and the emission treatment includes the following steps:

[0075] a. Opening the discharge port: Open the reserved outlet of the split-type impurity removal tank;

[0076] b. Three-phase discharge: Discharge the three-phase mixture, including solid precipitation, liquid feed liquid, and supernatant;

[0077] c. Cleaning the tank body: After the discharge is completed, clean the tank body and prepare for the next operation.

[0078] The separation of the extraction production line includes the following steps:

[0079] a. Feed liquid transfer: Transfer the treated feed liquid to the extraction production line;

[0080] b. Extraction operation: Separate the rare earth elements through an extraction tower, utilizing the extraction characteristics of different rare earth elements;

[0081] c. Collection of single rare earth: Collect the separated single rare earth solution and prepare for the next precipitation and calcination.

[0082] The split-type impurity removal tank, which is applied to the above-mentioned rare earth ore leaching and impurity removal process, includes several mixing tanks and clarification tanks, and is connected by pipelines to form a pre-stage A, an intermediate stage B, and a post-stage C that are sequentially connected. The pre-stage A includes two mixing tanks and two clarification tanks, which are connected in parallel by pipelines. The intermediate stage B includes three mixing tanks connected in series by pipelines. The post-stage C includes two mixing tanks and five clarification tanks, which are connected in series by pipelines.

[0083] The pre-stage A is used to complete the removal of iron ions, and the action steps include:

[0084] a. Clean the mixing tank and the clarifying tank to ensure no impurities.

[0085] b. Stir and mix the rare earth liquor and N-235 in the first mixing tank, and control the Fe3+ concentration to be less than 0.1 mg / L.

[0086] c. After sufficient mixing, transfer the liquor to the first clarifying tank for preliminary sedimentation, and then transfer the obtained liquor to the second mixing tank, where it is diluted with water and stirred again.

[0087] d. Transfer the obtained liquor to the second clarifying tank for further sedimentation until iron ions are fully removed.

[0088] The middle section B is used for the addition and mixing of lye, and the mixing tanks connected in series by pipelines correspond to the initial stage, the middle stage, and the final stage of lye addition one by one.

[0089] An outlet is reserved in the middle of the mixing tank for discharging the three phases, and there is no need to open the tank cover to dig the three phases.

[0090] Principle of this process: The dissolution of rare earth raw ore is the primary step in the rare earth extraction process. In this process, the rare earth raw ore mixture reacts with hydrochloric acid, and the acidic environment of hydrochloric acid is used to promote the dissolution of rare earth elements from the ore, forming a rare earth chloride solution. The principle of this process is based on the reaction between an acid and rare earth oxides or carbonates, releasing rare earth ions. Subsequently, in the step of removing sulfate ions, by adding barium salts, barium ions react with sulfate ions to form barium sulfate precipitate that is insoluble in water. Then, through a filter press, insoluble particles such as sand and barium sulfate are filtered out together, thus obtaining a pure rare earth feed solution. The role of this step is to remove sulfate ions that affect the subsequent extraction efficiency and ensure the purity of the rare earth feed solution. In the step of removing iron ions, the rare earth feed solution enters the impurity removal tank, and N-235 iron removal agent is added. Through chelation reaction, the concentration of Fe3+ ions is reduced to less than 0.1 mg / L. This step is to prevent iron ions from forming precipitates or affecting the extraction efficiency of rare earths in the subsequent process. Next, in the step of removing aluminum ions in the split-type impurity removal tank, the concentration of Al3+ ions is further reduced to less than 100 mg / L to avoid the hydrolysis of aluminum ions in the feed solution to form flocculent precipitates, which affect the extraction efficiency and the purity of rare earths; in the stirring and mixing step, the design of the split-type impurity removal tank allows for a reserved outlet in the middle to discharge the three phases, and the three-phase discharge can be completed without opening the tank cover plate. This design makes the stirring more uniform and improves the impurity removal efficiency. In the discharge treatment step, the reserved outlet in the middle of the tank can effectively handle the three-phase separation, that is, the separation of solids, liquids, and supernatant. This step is crucial for maintaining the purity of the rare earth feed solution and the smooth progress of the subsequent extraction process. In the separation step of the extraction production line, the rare earth feed solution treated by impurity removal enters the extraction production line, and the rare earth elements are separated using their different chemical properties to obtain single rare earth elements. Finally, in the precipitation and calcination step, the rare earth elements are precipitated from the solution by chemical precipitation methods, and then through high-temperature calcination, the rare earth compounds are converted into rare earth oxides, which is the final product form of rare earth elements, with high purity and wide industrial application value. The design of the entire process flow aims to improve the extraction efficiency of rare earths, reduce costs, and ensure the high purity and quality of rare earth products to meet the high standards of modern industry for rare earth materials.

[0091] The above describes the embodiments of the present invention. However, these embodiments are not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative and not restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make many forms, all of which fall within the protection scope of this embodiment.

Claims

1. The rare earth ore leaching and impurity removal process is characterized in that, It includes the following steps: Step 1, dissolution of rare earth raw ore: The rare earth raw ore mixture is dissolved with hydrochloric acid; Step 2, removal of sulfate radical: Barium salt is added to remove sulfate radical, and the sand and insoluble particles and barium sulfate are filtered through a pressure filter to obtain rare earth liquor; Step 3. Removal of iron ions: The above-mentioned rare earth liquor enters the impurity removal tank, and N-235 is first used to remove iron ions, controlling the Fe 3+ concentration to be less than 0.1 mg / L; Step 4. Remove aluminum ions: The above-mentioned feed liquid enters the split-type impurity removal tank to remove aluminum ions, and the Al 3+ concentration is controlled to be less than 100 mg / L; Step 5, separation by extraction production line: The above-mentioned liquor enters the extraction production line for separation to become single rare earth; Step 6, precipitation and calcination: It becomes rare earth oxide through precipitation and calcination; In the fourth step, the mixing and clarification of the liquor are carried out separately. During the mixing process, the lye is added while stirring and dispersing, the pH is adjusted to 4.0 - 4.5, the stirring speed of the liquor is controlled at 200 - 300 rpm, and the reaction time is controlled at 15 - 20 min; The clarification is carried out by static sedimentation. The sedimentation time is controlled at 30 - 60 min. The supernatant liquid in the clarification interface overflows in sequence until it enters the next process, and the lower layer of sediment is concentrated and discharged into the pressure filter for recovery.

2. The rare earth ore leaching and impurity removal process according to claim 1, characterized in that, In the mixing process, the addition of lye is divided into three stages: Initial stage: Add 40% of the total amount of lye and adjust the pH to 3.0 - 3.5; Middle stage: Add 30% and slowly increase the pH to 4.0 - 4.2; Final stage: Add the remaining 30% and finely adjust to the target pH of 4.5; The interval between each addition is 2 - 3 minutes, and it is dynamically adjusted in cooperation with on-line pH monitoring.

3. The rare earth ore leaching and impurity removal process according to claim 1, characterized in that, The dissolution of the rare earth raw ore includes the following steps: a. Preparation of rare earth raw ore: The rare earth raw ore is pretreated, including crushing and screening, to increase the contact area between the ore and the acid; b. Hydrochloric acid dissolution: The pretreated rare earth raw ore is mixed with hydrochloric acid, and the temperature and time are controlled to fully dissolve the rare earth elements; c. Solution collection: The dissolved solution is collected and prepared for the next impurity removal treatment.

4. The rare earth ore leaching and impurity removal process according to claim 1, characterized in that, The removal of sulfate radical includes the following steps: a. Barium salt addition: An appropriate amount of barium salt is added to the rare earth liquor to react with the sulfate radical to form insoluble barium sulfate; b. Mixing reaction: The rare earth liquor is fully stirred to ensure that the barium salt reacts completely with the sulfate radical; c. Pressure filtration: The insoluble particles and the generated barium sulfate are filtered off using a pressure filter to obtain pure rare earth liquor.

5. The rare earth ore leaching and impurity removal process according to claim 1, characterized in that, In the second, third, and fourth steps, discharge treatment is cooperatively set. The discharge treatment includes the following steps: a. Opening the discharge port: Open the reserved outlet of the split-type impurity removal tank; b. Three-phase discharge: Discharge the three-phase mixture, including solid precipitate, liquid liquor, and supernatant liquid; c. Cleaning the tank body: After the discharge is completed, clean the tank body and prepare for the next operation.

6. The rare earth ore leaching and impurity removal process according to claim 2, characterized in that, The separation by the extraction production line includes the following steps: a. Liquor transfer: Transfer the treated liquor to the extraction production line; b. Extraction operation: Separate the rare earth elements through an extraction tower, utilizing the extraction characteristics of different rare earth elements; c. Collection of single rare earth: Collect the separated single rare earth solution and prepare for the next precipitation and calcination.

7. Split-type impurity removal tank, applied to the rare earth ore leaching and impurity removal process described in any one of claims 1-6, characterized in that, It includes several mixing tanks (10) and clarification tanks (20), which are connected by pipelines to form a pre-stage A, a middle-stage B, and a post-stage C that are connected in sequence. The pre-stage A includes two mixing tanks (10) and two clarification tanks (20), which are connected in parallel by pipelines. The middle-stage B includes three mixing tanks (10) connected in series by pipelines. The post-stage C includes two mixing tanks (10) and five clarification tanks (20), which are connected in series by pipelines.

8. The split type impurity removal tank according to claim 7, characterized in that, The pre-stage A is used to complete the removal of iron ions, and the operation steps include: a. Clean the mixing tank (10) and the clarification tank (20) to ensure no impurities; b. Stir and mix the rare earth liquor and N-235 in the first mixing tank (10), and control the Fe3+ concentration to be less than 0.1 mg / L; c. After sufficient mixing, the liquor is introduced into the first clarification tank (20) for preliminary sedimentation. The obtained liquor is introduced into the second mixing tank (10) and diluted with water and stirred again; d. The obtained liquor is introduced into the second clarification tank (20) for further sedimentation until iron ions are completely removed.

9. The split type impurity removal tank according to claim 7, characterized in that, The middle-stage B is used for the addition and mixing of lye. The mixing tanks (10) connected in series included therein correspond one by one to the initial stage, the middle stage, and the final stage of lye addition.

10. The split type impurity removing tank according to claim 7, wherein, An outlet (100) is reserved in the middle of the mixing tank (10) for discharging three phases, and there is no need to open the tank cover to dig the three phases.

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