A method for jointly extracting ferro-niobium from Bayan Obo rare earth tailings

Abstract

The present invention relates to a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings, belonging to the technical field of mineral recovery metallurgy, and solving at least one of the problems of low recovery efficiency, environmental pollution by hydrofluoric acid, and low extraction efficiency of niobium in the prior art. The method includes: pickling the Bayan Obo rare earth tailings, filtering to obtain pickling solution and filter residue; drying the filter residue, mixing it with ammonium sulfate and concentrated sulfuric acid, roasting, and leaching niobium for the first time; mixing the mixture after the first leaching with fluoride salt and water, leaching niobium for the second time, separating solid and liquid, extracting niobium from the obtained filtrate to obtain raffinate and an extraction solution containing niobium ions; mixing the pickling solution and the raffinate, adjusting the pH to 3 - 4.5, then adding hydrogen peroxide solution, and carrying out a precipitation reaction to form Fe(OH)3 precipitate. This method can realize the joint extraction of niobium and iron from Bayan Obo rare earth tailings, avoid the use of hydrofluoric acid, and has a relatively high leaching rate of niobium.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral recovery metallurgy, and particularly relates to a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings. Background Art

[0002] Bayan Obo rare earth tailings are the products after iron separation, rare earth separation and bulk flotation of Bayan Obo iron ore, and are the raw materials for producing niobium concentrate. The mineral composition of Bayan Obo rare earth tailings is complex, mainly including magnetite, pyrite, dolomite, fluorite and quartz, and there are many types of niobium-containing minerals and niobium minerals. Among them, the content of iron oxide is 28.464%, the content of magnesium oxide is 5.573%, and the content of calcium oxide is 13.398%. The high contents of iron, magnesium and calcium affect the extraction of niobium. The content of niobium oxide is 0.10%, exceeding the ore deposit boundary grade of niobium oxide of 0.05%. The increasing rare earth tailings are piled up in the tailings pond, with low utilization value, occupying land and polluting the environment. Excessive tailings may also cause the breach of the tailings pond, which is very dangerous. The problem of reasonably recycling and utilizing tailings still needs to be solved.

[0003] In the prior art, there is only a method for extracting and recovering niobium from Bayan Obo rare earth raw ore, and there is no recovery and treatment method for Bayan Obo rare earth tailings. When using the existing method for extracting niobium from Bayan Obo rare earth raw ore to extract niobium from Bayan Obo rare earth tailings, the niobium extraction efficiency is low, and the existing technology uses a mixture of high-concentration hydrofluoric acid and sulfuric acid for leaching. During the leaching process, hydrofluoric acid is easy to volatilize when heated, polluting the environment and endangering human health. Hydrofluoric acid is easy to corrode equipment, increasing the cost of extracting niobium; in addition, the existing method can only extract niobium and does not recycle other metals, resulting in low recovery efficiency. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings to solve at least one of the following problems existing in the existing methods: (1) only niobium can be extracted and other metals are not recycled, resulting in low recovery efficiency; (2) hydrofluoric acid pollutes the environment, endangers human health and corrodes equipment; (3) the efficiency of extracting niobium is low.

[0005] The present invention provides a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings, and the method includes:

[0006] Step (1): Pickle Bayan Obo rare earth tailings and filter to obtain pickling solution and filter residue;

[0007] Step (2): Dry the filter residue, mix it with ammonium sulfate and concentrated sulfuric acid, roast it, and leach niobium for the first time; mix the mixture after the first leaching with fluoride salt and water, leach niobium for the second time, separate the solid and liquid, and extract niobium from the obtained filtrate to obtain raffinate and an extraction solution containing niobium ions;

[0008] Step (3): Mix the pickling solution and the raffinate, adjust the pH to 3 - 4.5, then add a hydrogen peroxide solution, and carry out a precipitation reaction to form Fe(OH) 3 precipitate.

[0009] Preferably, in step (1), the pickling is carried out using dilute hydrochloric acid.

[0010] Preferably, the concentration of the dilute hydrochloric acid is 2 - 2.5 mol / L.

[0011] Preferably, the volume ratio of the dilute hydrochloric acid to the mass of the low - grade niobium - containing ore is 5 - 10:1.

[0012] Preferably, the temperature of the pickling is 60 - 90 °C.

[0013] Preferably, the time of the pickling is 1 - 1.5 h.

[0014] Preferably, in step (3), adjusting the pH to 3 - 4.5 includes: first adding a 5 - 7 mol / L NaOH solution to adjust the pH value to 2 - 2.5, and then adding a 1 - 2 mol / L Na 2 CO 3 solution to adjust the pH value to 3 - 4.5.

[0015] Preferably, in step (3), the mass concentration of the hydrogen peroxide solution is 25 - 30%.

[0016] Preferably, the volume ratio of the mixed solution of the pickling solution and the raffinate to the hydrogen peroxide solution is 20:1 - 5.

[0017] Preferably, in step (3), the temperature of the precipitation reaction is 50 - 80 °C.

[0018] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0019] 1. The method of the present invention extracts niobium from Bayan Obo rare - earth tailings by ammonium sulfate - enhanced sulfuric acid roasting - fluoride salt two - stage leaching, and extracts iron through the precipitation reaction of the pickling solution and the raffinate, thereby enabling the combined extraction of niobium and iron from Bayan Obo rare - earth tailings (the niobium leaching rate in the preferred embodiment can reach 82%, and the iron extraction rate can reach 45%), with high recovery efficiency.

[0020] 2. The method of the present invention, which adopts ammonium sulfate - enhanced sulfuric acid roasting - fluoride salt two - stage leaching, can effectively improve the niobium extraction efficiency from Bayan Obo rare - earth tailings. Sulfuric acid roasting destroys the mineral structure and releases niobium elements. Ammonium sulfate enhances sulfuric acid roasting, and fluoride ions are easily complexed with niobium to form NbF 6 - and NbOF 5 2-, enabling niobium ions to enter the leaching solution, increasing the leaching rate (also known as the extraction rate) of niobium, and thus improving the niobium extraction efficiency; moreover, the present invention does not use hydrofluoric acid, reducing environmental pollution and the hazards brought by hydrofluoric acid.

[0021] 3. In the Bayan Obo rare earth tailings of the present invention, the content of niobium is low and the content of silicon dioxide is high. Only by sulfuric acid leaching in the existing methods, the niobium in silicon dioxide cannot be leached out, while the existing hydrofluoric acid leaching will pollute the environment. The present invention adds fluoride ions during the water leaching process. On the one hand, fluoride ions destroy silicate in an acidic solution, releasing the niobium stored in the silicate. On the other hand, fluoride ions easily complex with niobium to form NbF 6 - and NbO 5 2- , enabling niobium ions to enter the leaching solution and increasing the leaching rate of niobium. The reason why the fluoride salt is not added in step (1) is that the fluoride salt easily reacts with strong acid (concentrated sulfuric acid) to generate hydrofluoric acid, and hydrofluoric acid volatilizes under high-temperature conditions. In this way, not only can it not play a role in destroying the silicate mineral structure, but it will also cause environmental pollution.

[0022] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained from the content specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings are only for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs represent the same components.

[0024] Figure 1 is a flow chart of the method for jointly extracting niobium and iron from Bayan Obo rare earth tailings of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will specifically describe the preferred embodiments of the present invention in conjunction with the drawings, wherein the drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0026] The present invention provides a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings, as Figure 1 shown, the method includes:

[0027] Step (1): Pickle the Bayan Obo rare earth tailings and filter to obtain the pickling solution and the filter residue;

[0028] Step (2): Dry the filter residue and mix it with ammonium sulfate and concentrated sulfuric acid, then roast to leach niobium for the first time; mix the mixture after the first leaching with fluoride salt and water, leach niobium for the second time, perform solid-liquid separation, and extract niobium from the obtained filtrate to obtain a raffinate and an extraction solution containing niobium ions.

[0029] Step (3): Mix the acid washing solution and the raffinate, adjust the pH to 3 - 4.5, then add hydrogen peroxide solution to carry out a precipitation reaction to form Fe(OH) 3 precipitate.

[0030] Compared with the prior art, the method of the present invention extracts niobium from Bayan Obo rare earth tailings through ammonium sulfate enhanced sulfuric acid roasting - fluoride salt two-stage leaching, and extracts iron through the precipitation reaction of the acid washing solution and the raffinate, so as to realize the combined extraction of niobium and iron from Bayan Obo rare earth tailings with high recovery efficiency.

[0031] Exemplarily, the mass content of niobium oxide in the Bayan Obo rare earth tailings is less than 0.12%.

[0032] It should be noted that the Bayan Obo rare earth tailings are the products after iron separation, rare earth separation and bulk flotation of Baotou iron ore. Its components include fluorite, quartz, magnetite, dolomite, and the specific chemical composition is shown in Table 1 below.

[0033] The method of the present invention is applicable to Bayan Obo rare earth tailings. In Bayan Obo rare earth tailings, the content of niobium is low and the content of silicon oxide is high. Only by sulfuric acid leaching in the existing methods, the niobium in silicon oxide cannot be leached, and the existing hydrofluoric acid leaching will pollute the environment. In the present invention, fluoride ions are added during the water leaching process. On the one hand, fluoride ions destroy silicate and release the niobium stored in silicate. On the other hand, fluoride ions are easy to complex with niobium to form NbF 6 - and NbOF 5 2- , so that niobium ions enter the leaching solution and the leaching rate of niobium is increased.

[0034] In order to initially extract iron from the tailings, at the same time avoid the generation of insoluble sulfates during the ammonium sulfate - sulfuric acid roasting process, and avoid the violent reaction between sulfuric acid and carbonate, resulting in the risk of overflowing the pot. Therefore, in the present invention, the Bayan Obo rare earth tailings are first pickled with acid to remove the carbonate impurities in the Bayan Obo rare earth tailings, improve the subsequent leaching efficiency of niobium, and at the same time, initially leach iron into the dilute hydrochloric acid solution. The carbonate impurities include carbonate forms of iron, calcium, magnesium, aluminum and other ions.

[0035] Exemplarily, in step (1), the pickling is carried out with dilute hydrochloric acid.

[0036] Exemplarily, the concentration of the dilute hydrochloric acid is 2 - 2.5 mol / L.

[0037] Exemplarily, the ratio of the volume of the dilute hydrochloric acid to the mass of the Bayan Obo rare earth tailings is 5 - 10 mL:1 g.

[0038] Exemplarily, the temperature of the pickling is 60 - 90 °C. If the pickling temperature is too low, the extraction rate of iron is low. If the pickling temperature is too high, niobium will enter the pickling solution, affecting the final leaching rate of niobium.

[0039] Exemplarily, the time of the pickling is 1 - 1.5 h.

[0040] Specifically, before pickling the Bayan Obo rare earth tailings, the Bayan Obo rare earth tailings are first screened through an 80 - mesh sieve to remove impurities such as leaves and small stones in the Bayan Obo rare earth tailings, and then the undersize is dried at 100 - 120 °C for 4 - 5 h.

[0041] The method of the present invention is applicable to the Bayan Obo rare earth tailings. In the Bayan Obo rare earth tailings, the content of niobium is low and the content of silicon oxide is high. Only by sulfuric acid leaching in the existing methods, the niobium in the silicon oxide cannot be leached out, and the existing hydrofluoric acid leaching will pollute the environment. In the present invention, by adding fluoride ions during the water leaching process, on the one hand, the fluoride ions destroy the silicate and release the niobium stored in the silicate, and on the other hand, the fluoride ions are easily complexed with niobium to form NbF 6 - and NbOF 5 2- , enabling the niobium ions to enter the leaching solution and improving the leaching rate of niobium.

[0042] Exemplarily, in step (2), the ratio of the mass of the Bayan Obo rare earth tailings to the mass of ammonium sulfate and the volume of concentrated sulfuric acid is 1 g:0.15 - 0.4 g:1 - 1.5 mL.

[0043] Exemplarily, in step (2), ammonium sulfate is first added to the Bayan Obo rare earth tailings. After the Bayan Obo rare earth tailings and ammonium sulfate are mixed evenly, concentrated sulfuric acid is added and mixed evenly. This can promote the consistency of the mineral reaction degree and improve the leaching rate of niobium.

[0044] Exemplarily, in step (2), the temperature of the primary leaching is 260 - 300 °C, such as 270 °C, 280 °C, 290 °C.

[0045] Exemplarily, in step (2), the time of the primary leaching is 2.0 - 2.5 h, such as 2.1 h, 2.2 h, 2.3 h, 2.4 h.

[0046] Exemplarily, after the primary leaching is completed, the sample is taken out and cooled to room temperature.

[0047] Exemplarily, in step (2), the mass ratio of Bayan Obo rare earth tailings to fluoride salt is 1:0.15 - 0.25. If there is too much fluoride salt, it will cause waste of sodium fluoride and generate excessive fluoride ions, which are difficult to handle. If there is too little fluoride salt, the extraction rate of niobium will decrease and niobium cannot be fully extracted.

[0048] In the present invention, in step (2), fluoride ions destroy silicate in an acidic solution and release niobium stored in the silicate.

[0049] Exemplarily, in step (2), after mixing the mixture after primary leaching with fluoride salt and water, the pH of the mixture is adjusted to 1.5 - 1.8, such as pH being 1.5, 1.6, 1.7, 1.8. If the pH value is too low, hydrofluoric acid is easily formed; if the pH value is too high, the leaching rate of niobium is affected.

[0050] Specifically, first add fluoride salt to the mixture after primary leaching, mix evenly, then add water, and then add a pH regulator to adjust the pH of the solution.

[0051] Exemplarily, dilute sulfuric acid and / or sodium hydroxide are used to adjust the pH value of the mixture.

[0052] Exemplarily, in step (2), the mass of Bayan Obo rare earth tailings to the volume of water is 1 g:20 - 30 mL.

[0053] Exemplarily, in step (2), the temperature of the secondary leaching is 60 - 80 °C, such as 60 °C, 65 °C, 70 °C, 75 °C.

[0054] Exemplarily, in step (2), the time of the secondary leaching is 1 - 2 h.

[0055] Exemplarily, during the secondary leaching in step (2), stirring is carried out, and the stirring speed is 300 - 500 r / min.

[0056] Exemplarily, in step (2), the fluoride salt is sodium fluoride.

[0057] Exemplarily, for extracting niobium from the obtained filtrate in step (2), it includes: making the volume of the filtrate up to 500 mL, concentrating the niobium solution after volume adjustment by 50 times, putting the concentrated solution and MIBK into a separating funnel, shaking and then standing until a stable layer separation of the organic phase and the aqueous phase appears in the separating funnel, and separating the organic phase; back-extracting niobium in the organic phase, taking the organic phase and 0.5 mol / L sulfuric acid and putting them into a separating funnel, shaking the separating funnel, waiting until the aqueous phase and the organic phase are completely separated, and extracting the aqueous phase, and this aqueous phase is the niobium-containing solution.

[0058] Exemplarily, the volume ratio of the concentrated solution to MIBK is 1:1 - 2.

[0059] Exemplarily, the volume ratio of the organic phase to sulfuric acid is 1:4 - 5.

[0060] Exemplarily, in step (3), adjusting the pH to 3 - 4.5 includes: first adding a 5 - 7 mol / L NaOH solution to adjust the pH value to 2 - 2.5, and then adding a 1 - 2 mol / L Na 2 CO 3 solution to adjust the pH value to 3 - 4.5.

[0061] Exemplarily, in step (3), the role of hydrogen peroxide is to oxidize Fe 2+ to Fe 3+ , and the mass concentration of the hydrogen peroxide solution is 25 - 30%.

[0062] Exemplarily, the volume ratio of the mixed solution of the pickling solution and the raffinate to the hydrogen peroxide solution is 20:1 - 5.

[0063] Exemplarily, in step (3), the temperature of the precipitation reaction is 50 - 80 °C. Too low or too high a temperature will affect the precipitation rate of iron.

[0064] Exemplarily, step (3) includes putting the precipitate into a muffle furnace and roasting it at 600 - 700 °C for 1 - 2 h, aiming to remove the water in the precipitate.

[0065] Next, the method for jointly extracting niobium and iron from Bayan Obo rare earth tailings of the present invention will be further described through specific examples.

[0066] The main components of the Bayan Obo rare earth tailings in the following examples and comparative examples are shown in Table 1.

[0067] Table 1

[0068] Component <![CDATA[Sodium 2 O]]> MgO <![CDATA[Al 2 O 3 > <![CDATA[SiO 2 > CaO <![CDATA[TiO 2 > MnO <![CDATA[Fe 2 O 3 > <![CDATA[Nb 2 O 5 > Wt.% 2.28 5.57 1.74 19.17 13.40 0.78 1.40 28.50 0.10

[0069] Example 1

[0070] This example provides a method for jointly extracting niobium and iron from Bayan Obo rare earth tailings, and the method includes:

[0071] (1) Pretreatment: Screening the Bayan Obo rare earth tailings through an 80 - mesh sieve to remove impurities such as leaves and small stones in the Bayan Obo rare earth tailings, and putting the undersize into a tray and drying it at 100 °C for 4 h.

[0072] (2) Hydrochloric acid pickling: Taking the Bayan Obo rare earth tailings and putting them into a round - bottom flask, adding 2 mol / L hydrochloric acid according to a liquid - to - solid ratio of 7:1; after connecting the round - bottom flask to a condensing reflux device, placing it in a water bath at 70 °C; with a rotor speed of 400 r / min and a pickling time of 1.2 h.

[0073] (3) Filtration separation: Use a vacuum filter to separate the filtrate and filter residue after pickling. Dry the filter residue at 100 °C for 1 hour, and retain the pickling solution.

[0074] Use XRF to detect and calculate that the removal rates of iron, magnesium, calcium, and aluminum in the Bayan Obo rare earth tailings after pickling are 29.51%, 64.76%, 66.85%, and 49.09% respectively, and the recovery rate of niobium is 86.84%. This recovery rate refers to the ratio of the remaining niobium in the tailings after pickling to the niobium in the tailings before pickling.

[0075] (4) Ammonium sulfate enhanced sulfuric acid roasting and first leaching: Put 2 g of the pickled tailings into a glass quartz crucible, add 0.6 g of ammonium sulfate and 2.5 mL of 98% concentrated sulfuric acid (the mass ratio of the tailings to the mass of ammonium sulfate and the volume ratio of concentrated sulfuric acid is 1:0.3:1.25). First, mix the tailings and ammonium sulfate evenly, and then mix with concentrated sulfuric acid. Place the glass quartz crucible in a muffle furnace at 290 °C and roast for 2 h. After roasting, take out the quartz glass crucible and cool it to room temperature.

[0076] (5) Fluoride salt second leaching: Add 0.3 g of sodium fluoride (the mass ratio of the tailings to sodium fluoride is 1:0.15) to the glass quartz crucible in step (4), add 50 mL of deionized water (the volume ratio of water to the mass of the tailings is 25:1), adjust the pH to 1.7, and place the glass quartz crucible in a constant temperature water bath. The water leaching temperature is 80 °C, the leaching time is 1 h, and the rotor speed is 400 r / min.

[0077] (6) Filtration separation: Use a vacuum filter to separate the filtrate and filter residue after leaching.

[0078] Detect the extraction rate of niobium: Use ICP-MS to detect the niobium content in the filtrate after the second leaching and calculate the leaching rate (extraction rate) of niobium to be 82%. The leaching rate is the ratio of the niobium content in the filtrate after the second leaching to the niobium content in the tailings before the first leaching.

[0079] (7) Extract niobium: Dilute the filtrate to 500 mL, concentrate the niobium solution after dilution by 50 times, take the concentrated solution and MIBK (volume ratio 1:1) and put them into a separatory funnel. Shake the separatory funnel for 3 min. After shaking, let the separatory funnel stand until the organic phase (extract) and the aqueous phase (raffinate) in the separatory funnel are stably separated, and separate the organic phase; Back-extract niobium in the organic phase. Take the organic phase and 0.5 mol / L sulfuric acid solution in a volume ratio of 1:4 and put them into a separatory funnel, shake the separatory funnel for 5 minutes. Wait until the aqueous phase and the organic phase are completely separated, extract the aqueous phase, and detect the niobium content.

[0080] Use MIBK to extract niobium from the solution, and the extraction rate reaches 87.2%. Use 0.5 mol / L sulfuric acid solution to back-extract niobium, and the dissolution rate of niobium almost reaches 100%.

[0081] (8) Mix the pickling solution and the raffinate, add 5 mol / L NaOH solution dropwise to the mixed solution, adjust the pH value of the mixed solution to 2, and then add 1 mol / L Na 2 CO 3 , and adjust the pH value of the mixed solution to 3;

[0082] Add H with a mass concentration of 25% dropwise to the mixed solution 2 O 2 solution, and the volume ratio of the mixed solution of the pickling solution and the raffinate to the hydrogen peroxide solution is 20:3. Oxidize Fe 2+ to Fe 3+ , form Fe(OH) 3 precipitate, separate the precipitate from the filtrate with a vacuum filter, and recover the precipitate. Put the precipitate into a muffle furnace and calcine it at 600 °C for 1 h.

[0083] The extraction rate of iron is 45%. The extraction rate of iron is the ratio of the iron content in the product after iron extraction roasting to the iron content in the tailings before pickling.

[0084] Example 2

[0085] This example provides the influence of the addition amount of ammonium sulfate on the niobium extraction rate. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the addition amounts of ammonium sulfate are 0.1 g, 0.2 g, 0.4 g, 0.5 g, 0.6 g, 0.7 g, and 0.8 g respectively.

[0086] Table 2

[0087] Amount of ammonium sulfate 0.1g 0.2g 0.4g 0.5g 0.6g 0.7g 0.8g Niobium leaching rate 70％ 71％ 78％ 78％ 78％ 76％ 78％

[0088] It can be seen from the data in Table 2 and Example 1 that when the addition amount of ammonium sulfate is 0.3 - 0.8 g (that is, the mass ratio of tailings to ammonium sulfate is 1:0.15 - 0.4), the leaching rate remains above 76%.

[0089] Example 3

[0090] This example provides the influence of the addition amount of concentrated sulfuric acid on the niobium extraction rate. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the solid-liquid ratios (g / mL) of tailings to concentrated sulfuric acid are 1:0.25, 1:0.5, 1:0.75, 1:1, and 1:1.5 respectively. The results are shown in Table 3.

[0091] Table 3

[0092]

[0093] As can be seen from the data in Table 3 and Example 1, when the solid-liquid ratio of tailings to concentrated sulfuric acid is 1:1 - 1.5, the final leaching rate of niobium can reach over 78%.

[0094] Example 4

[0095] This example provides the influence of roasting temperature on the extraction rate of niobium. A method for jointly extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the roasting temperatures are 200°C, 230°C, 260°C, 280°C, 300°C, and 320°C respectively. The results are shown in Table 4.

[0096] Table 4

[0097] Roasting temperature 200℃ 230℃ 260℃ 280℃ 300℃ 320℃ Niobium leaching rate 67％ 64％ 71％ 82％ 82％ 29％

[0098] As can be seen from the data in Table 4 and Example 1, when the roasting temperature is 260 - 300°C, the extraction rate of niobium reaches over 70%, and when the roasting temperature is 260 - 300°C, the extraction rate of niobium reaches over 71%.

[0099] Example 5

[0100] This example provides the influence of roasting time on the extraction rate of niobium. A method for jointly extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the roasting times are 0.5 h, 1.0 h, 1.5 h, and 2.5 h respectively. The results are shown in Table 5.

[0101] Table 5

[0102] Roasting time 0.5h 1.0h 1.5h 2.5h Niobium leaching rate 73％ 72％ 76％ 82％

[0103] As can be seen from the data in Table 5 and Example 1, when the roasting time exceeds 2 h, the extraction rate of niobium remains basically unchanged. Therefore, the preferred roasting time in the present invention is 2 - 2.5 h.

[0104] Example 6

[0105] This example provides the influence of the addition amount of sodium fluoride during the water leaching process on the extraction rate of niobium. A method for jointly extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the addition amounts of sodium fluoride are 0.1 g, 0.2 g, 0.4 g, and 0.5 g respectively. The results are shown in Table 6.

[0106] Table 6

[0107] Dosage of sodium fluoride 0.1g 0.2g 0.4g 0.5g Niobium leaching rate 13％ 31％ 82％ 82％

[0108] As can be seen from the data in Table 6 and Example 1, for 2 g of tailings, when the amount of sodium fluoride used is above 0.3 g, the leaching rate of niobium is the highest, and when the amount of sodium fluoride used exceeds 0.3 g, the leaching rate of niobium remains basically unchanged.

[0109] Example 7

[0110] This example provides the effect of pH value on the niobium extraction rate during the water immersion process. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the pH value is adjusted by dropping sodium hydroxide solution and sulfuric acid solution, and the pH value of the leaching solution is adjusted to 2.0.

[0111] The niobium leaching rate in this example is 67%.

[0112] Example 8

[0113] This example provides the effect of the temperature of secondary leaching on the niobium extraction rate. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the temperature of secondary leaching is 50 °C.

[0114] The niobium leaching rate in this example is 68%.

[0115] Example 9

[0116] This example provides the effect of the dosage of dilute hydrochloric acid on the iron extraction rate. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that in step (2), the liquid-solid ratio of dilute hydrochloric acid to Bayan Obo rare earth tailings is 3:1.

[0117] The iron extraction rate in this example is 39%.

[0118] Example 10

[0119] This example provides the effect of the dosage of H 2 O 2 solution on the iron extraction rate. A method for co-extracting niobium and iron from Bayan Obo rare earth tailings similar to that in Example 1 is adopted. The difference is that the volume ratio of the mixed solution of pickling solution and raffinate to hydrogen peroxide solution is 20:0.5.

[0120] The iron extraction rate in this example is 35%.

[0121] Comparative Example 1

[0122] This comparative example adopts the method of ammonium sulfate sulfur roasting + water leaching + oxalic acid leaching to extract niobium from Bayan Obo rare earth tailings. This method is similar to that in Example 1. The difference is that after the initial roasting and leaching of ammonium sulfate concentrated sulfuric acid roasting, water is added to the mixture for water leaching, and then solid-liquid separation is carried out to obtain the first filtrate and the first filter residue. The first filter residue is mixed with oxalic acid. After the oxalic acid leaching is completed, solid-liquid separation is carried out to obtain the second filtrate and the second filter residue. The total content of niobium in the obtained first filtrate and second filtrate is detected and the extraction rate is calculated to be 54.6%.

[0123] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for jointly extracting ferroniobium from Bayan Obo rare earth tailings, characterized in that: The method comprises: Step (1): pickling the Bayan Obo rare earth tailings, filtering them, and obtaining a pickling solution and filter residue; Step (2): drying the filter residue, mixing it with ammonium sulfate and concentrated sulfuric acid, roasting it, and leaching niobium for the first time; mixing the mixture after the first leaching with fluoride salt and water, leaching niobium for the second time, separating the solid and liquid, extracting niobium from the obtained filtrate, and obtaining a raffinate and an extract containing niobium ions; Step (3): mixing the pickling liquid and the raffinate, adjusting the pH to 3-4.5, and then adding a hydrogen peroxide solution to perform a precipitation reaction to form a Fe(OH)3 precipitate; Before pickling the Bayan Obo rare earth tailings, the Bayan Obo rare earth tailings are first sieved through an 80-mesh sieve, and the sieved material is dried at 100-120° C. for 4-5 hours; In the step (1), the pickling is performed using dilute hydrochloric acid, the concentration of which is 2-2.5 mol / L; In the step (2), the ratio of the mass of the Bayan Obo rare earth tailings to the mass of ammonium sulfate and the volume of concentrated sulfuric acid is 1 g: 0.15-0.4 g: 1-1.5 mL; In the step (2), the temperature of the initial leaching is 260-300° C., the time of the initial leaching is 2.0-2.5 hours, and after the initial leaching is completed, the sample is taken out and cooled to room temperature; In the step (2), the mass ratio of the Bayan Obo rare earth tailings to the fluoride salt is 1:0.15-0.25; In the step (2), the pH value of the mixture after the initial leaching is mixed with fluoride salt and water is 1.5-1.8; In the step (2), the ratio of the mass of the Bayan Obo rare earth tailings to the volume of water is 1 g: 20-30 mL; The secondary leaching temperature is 60-80°C, and the secondary leaching time is 1-2h; The mass content of niobium oxide in the Bayan Obo rare earth tailings is less than 0.12%.

2. The method according to claim 1, characterized in that: The ratio of the volume of the dilute hydrochloric acid to the mass of the low-grade niobium-containing ore is 5-10:

1.

3. The method according to claim 1, characterized in that The pickling temperature is 60-90°C.

4. The method according to claim 1, characterized in that: The pickling time is 1-1.5h.

5. The method according to claim 1, characterized in that In step (3), the pH value is adjusted to 3-4.5, comprising: first adding 5-7 mol / L NaOH solution to adjust the pH value to 2-2.5, and then adding 1-2 mol / L Na2CO3 solution to adjust the pH value to 3-4.

5.

6. The method according to claim 1, characterized in that In step (3), the mass concentration of the hydrogen peroxide solution is 25-30%.

7. The method according to claim 6, characterized in that In step (3), the volume ratio of the mixed solution of the pickling liquid and the raffinate to the hydrogen peroxide solution is 20:1-5.

8. The method according to claim 1, characterized in that In step (3), the temperature of the precipitation reaction is 50-80°C.

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