Method for selectively removing iron from rare earth pickle liquor

Abstract

The invention relates to the technical field of selective impurity removal of valuable elements in acid solutions, in particular to a method for selective iron removal of rare earth pickle liquor. The method comprises the following specific steps: firstly, taking pickle liquor generated in an industrial production process, adding a first medicament, and stirring for pretreatment; adding a second medicament into the pretreated solution, and stirring to selectively remove iron; finally, a coagulant is added for solid-liquid separation, and supernate and iron-containing sediment are obtained. The total iron content in the supernate is lower than 5.0 mg / L, so that the production requirements of enterprises are met. The method has the advantages of simple and easy process, low equipment requirement, convenience in operation, wide application range and the like, and has good social benefits and economic values.

Description

Technical Field

[0001] The present invention relates to the technical field of selective impurity removal of acid leaching solution rich in valuable elements, and specifically to a method for selective iron removal of acid leaching solution rich in valuable elements in the rare earth industry. In particular, the method of "acidity control" + "catalytic iron precipitation" realizes the selective, rapid, efficient and inexpensive removal of iron in the acid leaching solution. Background Art

[0002] my country is rich in rare earth mineral resources and is known as the Kingdom of Rare Earths. The development and application of rare earth resources are mainly divided into mining, smelting, separation, processing and other steps. Rare earth ore is processed through beneficiation, smelting, separation and other processes to obtain crude products, and the crude products are further processed into rare earth superconducting materials, rare earth luminescent materials, rare earth permanent magnetic materials, rare earth hydrogen storage materials, rare earth catalytic materials, rare earth alloy materials and other functional materials. These materials are widely used in electronic communications, information storage, new energy batteries, artificial intelligence and other fields. At present, the decomposition and smelting of rare earth concentrates generally adopt concentrated sulfuric acid roasting, caustic soda decomposition, high-temperature chlorination and other processes. The concentrate is first made into rare earth sulfate solution or rare earth chloride solution. In this process, most of the iron in the concentrate remains in the slag in the form of insoluble compounds, and a small amount of iron impurities enter the solution in the form of ions. On-site generally uses the difference in solubility product to hydrolyze the impurity ions into hydroxide precipitation for removal. Although this impurity removal process is mature, there are disadvantages in the impurity removal process such as colloidal product adsorption and entrainment of rare earths, resulting in a large loss of resources, which needs to be continuously improved. Therefore, in order to make the iron removal slag easier to filter and reduce the loss of rare earth entrainment, it is necessary to explore a new method for selective iron removal from rare earth acid leaching solution. Summary of the invention

[0003] The invention discloses a method for selectively removing iron from acid leaching solution rich in valuable elements in rare earth industry, so as to solve any of the above and other potential problems in the prior art.

[0004] In order to achieve the above object, the technical solution of the present invention is:

[0005] A method for selectively removing iron from an acid leaching solution rich in valuable elements in the rare earth industry, the method specifically comprising the following steps:

[0006] S1) reduction pretreatment: weigh a certain amount of iron-containing acid leaching solution produced in the rare earth industrial production process, first add the first reagent and stir to obtain a solution after reduction pretreatment;

[0007] S2) Selective iron removal: adding a certain amount of a second reagent to the solution obtained in S1) while stirring to obtain a mixed solution;

[0008] S3) adding a coagulant to the mixed solution obtained in S2) to separate the solid from the liquid to obtain a supernatant and an iron-containing precipitate.

[0009] Furthermore, the total iron content in the acidic supernatant obtained in S3) is lower than 5 mg / L.

[0010] Furthermore, the pH value of the acid leaching solution in S1) is 0.1-4, and the iron concentration in the iron-containing acid leaching solution is not less than 10.0 mg / L.

[0011] Furthermore, after adding the first agent in S1), the pH value of the iron-containing acid leaching solution is adjusted to be less than 3.5.

[0012] Furthermore, the first agent is at least one of iron powder, sodium sulfite, sodium thiosulfite, sodium bisulfite, sodium pyrosulfite, and sodium dithionite.

[0013] Furthermore, the specific process parameters of the reduction pretreatment in S1) are:

[0014] The amount of reducing agent added is such that the molar ratio of the agent to the trivalent iron ions in the iron-containing acid leaching solution is 2:1 to 1:1;

[0015] The stirring speed is 10-800 r / min, and the stirring time is 5-60 min.

[0016] Furthermore, the second agent is a compound containing ferrocyanide ions.

[0017] Furthermore, the compound containing ferrocyanide ions is one or a combination of potassium ferrocyanide and sodium ferrocyanide.

[0018] Furthermore, the specific process parameters of the selective iron removal in S2) are:

[0019] The amount of the second agent added is such that the molar ratio of the iron removal agent to the ferrous ions in the iron-containing acid leaching solution is 1.1:1 to 1:1;

[0020] The stirring speed is 10-800 r / min, and the stirring time is 5-60 min.

[0021] Furthermore, the process parameters of the solid-liquid separation in S3) are:

[0022] The reaction temperature is room temperature;

[0023] The amount of the coagulant added is such that the volume ratio of the coagulant to the iron-containing acidic solution is 2:1000 to 6:1000;

[0024] The standing time is 1 to 60 minutes.

[0025] Furthermore, the coagulant is one or a combination of polyacrylamide, sodium polyacrylate and polyvinyl alcohol.

[0026] The advantages of the technical solution of the present invention are:

[0027] 1. The present invention is carried out under strong acidic conditions, which can effectively inhibit the hydrolysis of other valuable elements, greatly reduce the loss rate of valuable elements, and improve production efficiency;

[0028] 2. The present invention utilizes the reaction of ferrous ions and ferrocyanide ions to generate a precipitate with extremely low solubility. The precipitate not only has less adsorption of other valuable elements, but can also react with alkali to regenerate iron precipitation reagents and iron slag, greatly reducing the cost of iron removal;

[0029] 3. The present invention is simple to operate, suitable for industrialization, and close to the existing processing technology of various enterprises.

[0030] The present invention adopts the method of "acidity control" + "catalytic iron precipitation" to effectively remove iron ions in the iron-containing acidic solution, so that the total iron concentration in the supernatant is lower than 5.0 mg / L, meeting the production needs of enterprises. The acidity control and step-by-step precipitation method adopted in the present invention has the advantages of simple process, low equipment requirements, convenient operation, wide environmental protection adaptability, etc., and has good social benefits and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flowchart of a method for selectively removing iron from a rare earth acid leaching solution. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the scope of protection claimed is not limited to the embodiments.

[0033] like Figure 1 As shown, the present invention provides a method for selectively removing iron from an acid leaching solution rich in valuable elements in the rare earth industry, and the method specifically comprises the following steps:

[0034] S1) reduction pretreatment: weigh a certain amount of iron-containing acid leaching solution produced in an industrial production process, first add a first reagent and stir to obtain a solution after reduction pretreatment;

[0035] S2) Selective iron removal: adding a certain amount of a second reagent to the solution obtained in S1) while stirring to obtain a mixed solution;

[0036] S3) adding a coagulant to the mixed solution obtained in S2) to separate the solid from the liquid to obtain a supernatant and an iron-containing precipitate.

[0037] Preferably, the first agent is at least one of iron powder, sodium sulfite, sodium thiosulfite, sodium bisulfite, sodium pyrosulfite, and sodium dithionite.

[0038] Preferably, the compound containing ferrocyanide ions is one or a combination of potassium ferrocyanide and sodium ferrocyanide.

[0039] Preferably, the coagulant is one or a combination of polyacrylamide, sodium polyacrylate and polyvinyl alcohol.

[0040] Implementation Case 1: Iron powder, sodium sulfite, sodium thiosulfate, sodium bisulfite, sodium metabisulfite, sodium dithionite

[0041] Take 1L of iron-containing acidic rare earth leaching solution from a rare earth smelting enterprise, with pH = 2.0 and total iron concentration of 1120 mg / L, add 300 mg of reduced iron powder and stir for 10 minutes, then add 5.9 g of potassium ferrocyanide to the above acidic solution, stir at a speed of 300 r / min, react at room temperature for 15 minutes, then stand for 5 minutes, filter to obtain iron-containing sediment and supernatant, and the iron ion in the supernatant is tested to be less than 5.0 mg / L, and the lanthanum ion loss rate is less than 1%.

[0042] Implementation Case 2:

[0043] Take 1L of iron-containing acidic rare earth leaching solution from a rare earth smelting enterprise, with pH = 1.4 and total iron concentration of 2800mg / L, add 200mg of sodium sulfite and stir for 15min, then add 11.2g of sodium ferrocyanide to the above acidic solution, stir at a speed of 400r / min, react at room temperature for 13min, then stand for 10min, filter to obtain iron-containing sediment and supernatant, and the iron ion in the supernatant is tested to be less than 5.0mg / L, and the lanthanum ion loss rate is less than 1%.

[0044] Implementation Case 3:

[0045] Take 1L of iron-containing acidic rare earth leaching solution from a rare earth smelting enterprise, with pH = 0.9 and total iron concentration of 1200mg / L, first add 250mg of sodium thiosulfate and stir for 30min, then add 4.5g of sodium ferrocyanide to the above acidic solution, stir at a speed of 500r / min, react at room temperature for 17min, then stand for 8min, filter to obtain iron-containing sediment and supernatant, and the iron ion in the supernatant is tested to be less than 5.0mg / L, and the cerium ion loss rate is less than 1.5%.

[0046] The above is a detailed introduction to a method for selective iron removal of a rare earth industry acid leaching solution rich in valuable elements provided in the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0047] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be subject to that defined in the attached claims.

[0048] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0049] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0050] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be included in the claims attached to the present application.

Claims

1. A method for selectively removing iron from rare earth acid leaching solution, characterized in that: The method specifically comprises the following steps: S1) reduction pretreatment: weigh a certain amount of iron-containing acid leaching solution produced in an industrial production process, first add a first reagent and stir to obtain a solution after reduction pretreatment; S2) Selective iron removal: adding a certain amount of a second reagent to the solution obtained in S1) while stirring to obtain a mixed solution; S3) adding a coagulant to the mixed solution obtained in S2) to separate the solid from the liquid to obtain a supernatant and an iron-containing precipitate.

2. The method according to claim 1, characterized in that: The total iron content in the acidic supernatant obtained in S3) is less than 5 mg / L.

3. The method according to claim 1, characterized in that The pH value of the iron-containing acid leaching solution in S1) is 0.1-4, and the iron concentration in the iron-containing acid leaching solution is not less than 10.0 mg / L; After adding the first agent, the pH value of the iron-containing acidic solution is adjusted to be less than 3.5; The specific process parameters of reduction pretreatment are: The first agent is added in an amount such that the molar ratio of the agent to the ferrous ions in the iron-containing acid leaching solution is 2:1 to 1:1; The stirring speed is 10-800 r / min, and the stirring time is 5-60 min.

4. The method according to claim 3, characterized in that The first agent is at least one of iron powder, sodium sulfite, sodium thiosulfite, sodium bisulfite, sodium pyrosulfite, and sodium dithionite.

5. The method according to claim 1, characterized in that: The second agent is a compound containing ferrocyanide ions.

6. The method according to claim 5, characterized in that The compound containing ferrocyanide ions is one of potassium ferrocyanide and sodium ferrocyanide or a combination of several of them.

7. The method according to claim 1, characterized in that The specific process parameters of the selective iron removal in S2) are: The amount of the second agent added is such that the molar ratio of the iron removal agent to the ferrous ions in the iron-containing acid leaching solution is 1.1:1 to 1:1; The stirring speed is 10-800 r / min, and the stirring time is 5-60 min.

8. The method according to claim 1, characterized in that The process parameters of the solid-liquid separation in S3) are: The reaction temperature is room temperature; The amount of the coagulant added is such that the volume ratio of the coagulant to the solution is 2:1000 to 6:1000; The standing time is 1 to 60 minutes.

9. The method according to claim 1, characterized in that: The coagulant is one or a combination of polyacrylamide, sodium polyacrylate and polyvinyl alcohol.

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