Method for removing Tl impurity in ammonium rhenate

Abstract

The invention relates to the technical field of ammonium rhenate purification, and particularly discloses a method for removing Tl impurities in ammonium rhenate. The method specifically comprises the following steps: dissolving ammonium rhenate in deionized water, adding an oxidant, carrying out an oxidation reaction while stirring, filtering, carrying out ion exchange, evaporation and concentration, adding ammonia water / ammonia gas to obtain an ammonium rhenate solution, freezing, crystallizing, and drying to obtain a high-purity ammonium rhenate solid. The method is simple to operate and ingenious in process, the oxidizing agent is added to oxidize and adsorb the Tl, impurities are not introduced, and the Tl which is not easily removed by ion exchange is removed, so that the high-purity ammonium rhenate is obtained. The Tl content is smaller than 0.9 ppm, and the purity of ammonium rhenate is larger than 99.999%.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of ammonium perrhenate purification, and more particularly to a method for removing Tl impurities in ammonium perrhenate. BACKGROUND

[0002] Rhenium itself has no independent deposit and is often dispersed in other non-ferrous metal ore bodies and is a by-product in the process of molybdenum and copper extraction, mainly coexisting with molybdenite and often existing in the form of rhenium sulfide in the form of trace elements associated with molybdenum, copper, lead, zinc, platinum and niobium. The main raw material for preparing rhenium products in the process is ammonium perrhenate. The main methods for extracting rhenium from molybdenum-containing rhenium leaching solution are oxidation roasting, but the product obtained by the method has low purity and needs further purification treatment. In the early stage, the rhenium is extracted by the oxidation roasting-precipitation method, which has simple process and low investment, but the product obtained by the method has low purity and poor quality, and the yield is also less.

[0003] At present, the main methods for industrialized purification of ammonium perrhenate at home and abroad are extraction, crystallization and ion exchange crystallization.

[0004] Extraction is a unit operation for separating a mixture by using different solubilities of components in solvents. That is, by using the different solubilities or distribution coefficients of substances in two mutually insoluble (or slightly soluble) solvents, the solute substances are transferred from one solvent to another solvent. At present, most of the ammonium perrhenate products are produced by extraction method. A small amount of organic matter is wrapped in the crude product during the purification process, and the organic matter and other impurities are difficult to remove completely during the purification process, resulting in unstable product quality.

[0005] Crystallization is a process of separating impurities by crystallizing and separating ammonium perrhenate from solution by using the principle that the solubility of ammonium perrhenate decreases when the temperature decreases. The effect of crystallization on the removal of impurities is very limited.

[0006] Ion exchange crystallization is a method for preparing pure rhenium acid solution by ion exchange method, and then neutralizing the solution to pH 8-9 with ammonia water or ammonia gas to convert rhenium acid into ammonium perrhenate.

[0007] In summary, the main problems of the extraction method are that a third phase is often produced, the rhenium recovery rate is low, the environment is polluted, the reagent consumption is large, and the cost is high. The ion exchange method has strong process adaptability, short process, simple operation, and high yield, and is very suitable for recovering rhenium from low rhenium-containing solution.

[0008] In the exploration of producing high-purity ammonium perrhenate, it is found that the copper smelting waste acid contains a high concentration of thallium (Tl) element, which has been the main impurity affecting the stable production of high-purity ammonium perrhenate. At present, there is no mature and reliable technology for separating thallium element. The Tl impurities in ammonium perrhenate come from its raw material arsenic sulfur slag, and are the most stubborn and difficult to remove impurities in the process of realizing 5N ammonium perrhenate high purification.

[0009] For Tl impurities, there are Tl + and Tl 3+ Two valence states, Tl + does not coordinate with organic functional groups, Tl 3+ ions have strong coordination ability, but when pH < 13, Tl + exists in ammonium rhenate solution, and is difficult to remove by resin adsorption.

[0010] Generally speaking, the content of Tl impurities in domestic ammonium rhenate is tens to hundreds of ppm (μg / g, g / t or mg / kg), and after being dissolved into ammonium rhenate solution, the concentration is hundreds of ppb to 1 ppm. SUMMARY

[0011] In order to remove Tl impurities in ammonium rhenate, the application provides a method for removing Tl impurities in ammonium rhenate. The application uses an oxidation adsorption, filtration, ion exchange combined process to remove Tl elements in ammonium rhenate solution, and obtain high-purity ammonium rhenate. The content of Tl is <0.9 ppm, and the purity of ammonium rhenate is >99.999%.

[0012] The application provides a method for removing Tl impurities in ammonium rhenate, which adopts the following technical scheme:

[0013] A method for removing Tl impurities in ammonium rhenate, the method specifically comprises the following steps: dissolving ammonium rhenate in deionized water, adding an oxidizing agent to perform an oxidation reaction while stirring, filtering, ion exchanging, evaporating and concentrating, then adding ammonia water / ammonia gas to obtain an ammonium rhenate solution, freezing and crystallizing the ammonium rhenate solution, and drying to obtain high-purity ammonium rhenate solid.

[0014] Optionally, the weight ratio of the ammonium rhenate to the deionized water is 1:(15-25).

[0015] In a specific embodiment, the weight ratio of the ammonium rhenate to the deionized water is 1:10, 1:15, 1:17.5, 1:20, 1:22.5, 1:25, or 1:30.

[0016] In some specific embodiments, the weight ratio of the ammonium rhenate to the deionized water is 1:(15-17.5), 1:(15-20), 1:(15-22.5), 1:(17.5-20), 1:(17.5-22.5), 1:(17.5-25), 1:(20-22.5), 1:(20-25), or 1:(22.5-25).

[0017] Optionally, the oxidizing agent comprises any one of sodium peroxide, sodium hypochlorite, potassium permanganate, manganese dioxide, and iron sulfate.

[0018] In one specific embodiment, the oxidizing agent is sodium peroxide.

[0019] In one specific embodiment, the oxidizing agent is sodium peroxide.

[0020] In one specific embodiment, the oxidizing agent is potassium permanganate.

[0021] In one specific embodiment, the oxidizing agent is manganese dioxide.

[0022] In one specific embodiment, the oxidizing agent is ferric sulfate.

[0023] Optionally, the feeding amount of the oxidizing agent is greater than 0.2wt%.

[0024] Optionally, the feeding amount of the oxidizing agent is 0.2-0.5wt%.

[0025] In one specific embodiment, the feeding amount of the oxidizing agent is 0.1wt%, 0.2wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.5wt%, 0.6wt%.

[0026] In some specific embodiments, the feeding amount of the oxidizing agent is 0.2-0.3wt%, 0.2-0.35wt%, 0.2-0.4wt%, 0.3-0.35wt%, 0.3-0.4wt%, 0.3-0.5wt%, 0.35-0.4wt%, 0.35-0.5wt%, 0.4-0.5wt%.

[0027] In the related art, for Tl impurities, there are Tl + and Tl 3+ two valence states, Tl + does not coordinate with organic functional groups, Tl 3+ ions have strong coordination ability, but when pH < 13, Tl elements in ammonium rhenate solution mainly exist in Tl + , which is difficult to remove by resin adsorption.

[0028] The present application introduces sodium peroxide as an oxidizing agent, which can oxidize Tl + to Tl 3+ , so that it can be adsorbed by ion exchange resin, thereby realizing the removal of Tl impurities, the reaction formula is 2H2O + O2 2- + Tl + = 4OH - + Tl 3+ , Na + ions are adsorbed and removed in the ion exchange process.

[0029] The application introduces sodium hypochlorite as an oxidant, which can oxidize Tl + to Tl 3+ , so that it can be adsorbed by ion exchange resin, and then the removal of Tl impurities is realized, and the reaction formula is H2O+ClO - +Tl + =Cl - +Tl 3+ +2OH - , Na ions are adsorbed and removed in the ion exchange process, Cl - ions have a large difference in solubility with ammonium rhenate, and Cl - ions have high solubility and are separated from ammonium rhenate in recrystallization.

[0030] The application introduces potassium permanganate as an oxidant, which can oxidize Tl + to Tl 3+ , so that it can be adsorbed by ion exchange resin, and then the removal of Tl impurities is realized, and the reaction formula is 4H2O+2MnO4 - +3Tl + =3Tl 3+ +2MnO2+8OH - , the generated manganese dioxide also has excellent adsorption performance, and can further adsorb Tl ions (including Tl + , Tl 3+ ) in the solution, the reaction process does not introduce other impurity ions, and K + ions are adsorbed and removed in the ion exchange process.

[0031] The application introduces iron sulfate as an oxidant, which can oxidize Tl + to Tl 3+ , so that it can be adsorbed by ion exchange resin, and then the removal of Tl impurities is realized, and the reaction formula is 2Fe 3+ +Tl + =Tl 3+ +2Fe 2+ , the reaction process does not introduce other impurity ions, and Fe 2+ ions are adsorbed and removed in the ion exchange process, SO4 2- ions have a large difference in solubility with ammonium rhenate, and SO4 2- ions have high solubility and are separated from ammonium rhenate in recrystallization.

[0032] The application introduces manganese dioxide as an oxidizing adsorbent, which can oxidize Tl + to Tl 3+ , so that it can be adsorbed by ion exchange resin, and the reaction formula is 2H2O+MnO2+Tl + =Tl 3+ +Mn2+ +4OH - , Mn 2+ ions are removed by adsorption during ion exchange; on the other hand, MnO2 as an adsorbent can capture and adsorb Tl ions (including Tl + , Tl 3+ ), further achieving the removal of Tl impurities. Based on the above, Tl impurities can be removed to <0.5 ppm under the dual action, and high-purity ammonium rhenate with a purity of >99.999% is prepared.

[0033] Reasons for the adsorption of manganese dioxide:

[0034] Generally, crystalline MnO2 is composed of [MnO6] octahedral units, which form various tunnel structures and layered structures by sharing corners or edges. There are many different crystal phases of MnO2, including α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and ε-MnO2, etc. They can be divided into two categories: one-dimensional tunnel structure and two-dimensional layered structure. In addition, α-MnO2, β-MnO2 and γ-MnO2 are one-dimensional tunnel structures of (1x1)(2x2), (1x1) and (1x1)(1x2), respectively. ε-MnO2 is similar in structure to γ-MnO2, but its manganese lattice is highly disordered and the tunnel shape is irregular. δ-MnO2 is a two-dimensional layered structure formed by [MnO6] octahedra sharing sides. In addition, α-MnO2, β-MnO2, γ-MnO2 and δ-MnO2 belong to tetragonal, tetragonal, hexagonal and monoclinic systems, respectively. Because MnO2 has many different crystal phase structures and these different crystal phases have different tunnel or layered structures, it is beneficial for ions, protons and electrons to migrate freely, which promotes adsorption performance, ion exchange and redox reactions.

[0035] Alternatively, the manganese dioxide is selected from one or more of α, β, γ, ε, δ and amorphous.

[0036] In a particular embodiment, the manganese dioxide is of the α type.

[0037] In a particular embodiment, the manganese dioxide is of the β type.

[0038] In a particular embodiment, the manganese dioxide is of the γ type.

[0039] In a particular embodiment, the manganese dioxide is of the ε type.

[0040] In a particular embodiment, the manganese dioxide is of the δ type.

[0041] In a particular embodiment, the manganese dioxide is of the amorphous type.

[0042] In one specific embodiment, the manganese dioxide is of the γ+α type.

[0043] In one specific embodiment, the manganese dioxide is of the γ+β type.

[0044] In one specific embodiment, the manganese dioxide is of the γ+ε type.

[0045] In one specific embodiment, the manganese dioxide is of the γ+δ type.

[0046] Optionally, the time of the redox reaction is 30-90 min.

[0047] In one specific embodiment, the time of the redox reaction is 30 min, 45 min, 60 min, 90 min.

[0048] In some specific embodiments, the time of the redox reaction is 30-45 min, 30-60 min, 45-60 min, 45-90 min, 60-90 min.

[0049] Optionally, the filtration adopts a membrane filtration process; the membrane is selected from a microporous filtration membrane, an ultrafiltration membrane, a reverse osmosis membrane.

[0050] In one specific embodiment, the membrane is a microporous filtration membrane.

[0051] In one specific embodiment, the membrane is an ultrafiltration membrane.

[0052] In one specific embodiment, the membrane is a reverse osmosis membrane.

[0053] In summary, the present application has the following beneficial effects:

[0054] The present application is simple in operation and ingenious in process. The oxidation of the adsorbed Tl by the oxidizing agent not only introduces no impurities, but also removes Tl which is not easy to be removed by ion exchange, thereby obtaining high-purity ammonium rhenate. The content of Tl is <0.9 ppm, and the purity of ammonium rhenate is >99.999%. DETAILED DESCRIPTION

[0055] Before describing the embodiments of the present application in detail, it should be understood that the terms used herein are for the purpose of describing specific embodiments only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term belongs.

[0056] The present application provides a method for removing Tl impurities in ammonium rhenate, which specifically comprises the following steps:

[0057] (1) Dissolving ammonium rhenate in deionized water, adding an oxidizing agent, and performing a redox reaction while stirring.

[0058] The weight ratio of ammonium rhenate to deionized water is 1:(15-25).

[0059] The oxidizing agent includes any one of sodium peroxide, sodium hypochlorite, potassium permanganate, manganese dioxide, and iron sulfate.

[0060] The amount of the oxidizing agent added is greater than 0.2wt%. Alternatively, the amount of the oxidizing agent added is 0.2-0.5wt%. In addition, the manganese dioxide is selected from one or more of alpha, beta, gamma, epsilon, delta, and amorphous forms. The time of the redox reaction is 30-90min.

[0061] (2) Filtering the solution after the redox reaction, ion-exchanging the filtered solution, evaporating and concentrating, and then adding ammonia water / ammonia gas to obtain an ammonium rhenate solution.

[0062] The membrane is selected from a microporous filtration membrane, an ultrafiltration membrane, and a reverse osmosis membrane. The temperature of the filtration is 20-60℃.

[0063] The filtered solution is ion-exchanged and impurities are removed using a cation exchange resin. The cation exchange resin is a C160 resin. The temperature of the evaporation and concentration is 80-100℃. In this application, the ammonia water is electronic grade ammonia water with a mass concentration of 25-28%, and the electronic grade ammonia water is added to adjust the pH of the solution to 7-9.

[0064] (3) Freezing and crystallizing the ammonium rhenate solution, and then drying to obtain high-purity ammonium rhenate solids.

[0065] The application is simple to operate and has a clever process. The addition of the oxidizing agent oxidizes and adsorbs Tl, does not introduce impurities, and removes Tl that is not easily removed by ion exchange, thereby obtaining high-purity ammonium rhenate. The content of Tl is <0.9ppm, and the purity of ammonium rhenate is >99.999%.

[0066] To make the purpose, technical solutions, and advantages of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the application.

[0067] The application will be further described in detail below in combination with the embodiments and test results.

[0068] Embodiments

[0069] Embodiment 1

[0070] The embodiment provides a method for removing Tl impurities in ammonium rhenate. The parameters and substance types involved in the method are specifically shown in Table 1.

[0071] The method specifically comprises the following steps:

[0072] (1) Dissolving ammonium rhenate in deionized water, adding an oxidizing agent, and performing a redox reaction while stirring. The weight ratio of ammonium rhenate to deionized water is 1:10, and the feeding amount of the oxidizing agent is greater than 0.35 wt%. In the embodiment, the oxidizing agent is manganese dioxide, and the manganese dioxide is in the gamma type. The time of the redox reaction is 60 min.

[0073] (2) Filtering the solution after the redox reaction, ion exchanging the filtered solution, evaporating and concentrating, and then adding ammonia water / ammonia gas to obtain an ammonium rhenate solution.

[0074] The membrane is selected from a microporous filter membrane, and the filtering temperature is 35 DEG C. The filtered solution is ion exchanged by using a cation exchange resin. The cation exchange resin is a C160 type resin, and the evaporation and concentration temperature is 90 DEG C. The ammonia water is electronic grade ammonia water, and the mass concentration of the electronic grade ammonia water is 25%. The electronic grade ammonia water is added to adjust the pH of the solution to 7-9.

[0075] (3) Freeze-crystallizing the ammonium rhenate solution and then drying to obtain high-purity ammonium rhenate solids.

[0076] Embodiment 2-33

[0077] Embodiments 2-33 respectively provide a method for removing Tl impurities in ammonium rhenate. The difference between the above embodiments and embodiment 1 is that the parameters and substance types involved in the method are specifically shown in Table 1. The rest can be referred to the method of embodiment 1.

[0078] The difference between embodiments 1-33 is specifically as follows:

[0079] The difference between embodiments 1-7 is that the weight ratio of ammonium rhenate to deionized water.

[0080] The difference between embodiments 4 and 8-13 is that the feeding amount of manganese dioxide.

[0081] The difference between embodiments 4 and 14-21 is that the crystal form of manganese dioxide.

[0082] The difference between embodiments 19 and 22-24 is that the time of the redox reaction.

[0083] The difference between embodiments 19 and 25-28 is that the type of the oxidizing agent.

[0084] The difference between Example 19 and Examples 29-31 is the filtration temperature.

[0085] The difference between Example 19 and Examples 32-33 is the content of Tl in the ammonium rhenate used.

[0086] Table 1: Parameters and substance types involved in the methods provided by the above examples

[0087]

[0088]

[0089] Detection test

[0090] ICP-MS (inductively coupled plasma mass spectrometer) and ICP-AES (inductively coupled plasma atomic emission spectrometer) were used to detect Tl in the high-purity ammonium rhenate prepared in the above examples. The detection results are shown in Table 2.

[0091] Table 2: Detection results of the high-purity ammonium rhenate prepared in the above examples

[0092]

[0093]

[0094] In summary, the application has the advantages of simple operation and ingenious process. The addition of oxidizing agent to oxidize and adsorb Tl not only does not introduce impurities, but also removes Tl which is not easy to be removed by ion exchange, thereby obtaining high-purity ammonium rhenate. The content of Tl is <0.9 ppm, and the purity of ammonium rhenate is >99.999%.

[0095] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the application, and not to limit them. Although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements to some technical features. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for removing Tl impurities from ammonium rhenate, characterized in that, The method specifically comprises the following steps: dissolving ammonium rhenate in deionized water, adding an oxidizing agent to perform an oxidation reaction while stirring, filtering, ion exchanging, evaporating and concentrating, adding ammonia water / ammonia gas to obtain an ammonium rhenate solution, freeze-crystallizing, and drying to obtain high-purity ammonium rhenate solid.

2. The method of claim 1, wherein, The weight ratio of the ammonium rhenate to the deionized water is 1: (15-25).

3. The method of claim 1, wherein, The oxidizing agent comprises any one of sodium peroxide, sodium hypochlorite, potassium permanganate, manganese dioxide, and iron sulfate.

4. The method of claim 1, wherein, The feeding amount of the oxidizing agent is greater than 0.2 wt%; optionally, the feeding amount of the oxidizing agent is 0.2-0.5 wt%.

5. The method of claim 3, wherein, The manganese dioxide is selected from one or more of alpha, beta, gamma, epsilon, delta, and amorphous forms.

6. The method of claim 1, wherein, The time of the oxidation-reduction reaction is 30-90 min.

7. The method of claim 1, wherein, The filtering adopts a membrane filtering process; the membrane is selected from a microporous filtering membrane, an ultrafiltration membrane, and a reverse osmosis membrane.

8. The method of claim 1, wherein, The filtering temperature is 20-60 ℃.

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