CN118979161B - Method for jointly extracting ferrocolumbium from Bayan obo rare earth tailings - Google Patents

Abstract

The invention relates to a method for jointly extracting ferroniobium from Bayan obo rare earth tailings, belongs to the technical field of mineral recovery metallurgy, and solves at least one of the problems of low recovery benefit, environmental pollution caused by hydrofluoric acid and low niobium extraction efficiency in the prior art. The method comprises the steps of carrying out acid washing on the Baiyunebo rare earth tailings, filtering to obtain acid washing liquid and filter residues, drying the filter residues, mixing the filter residues with ammonium sulfate and concentrated sulfuric acid, roasting, carrying out primary niobium leaching, mixing the mixture obtained after primary niobium leaching with fluoride salt and water, carrying out secondary niobium leaching, carrying out solid-liquid separation, extracting niobium from the obtained filtrate to obtain raffinate and extract containing niobium ions, mixing the acid washing liquid and the raffinate, adjusting the pH to 3-4.5, adding hydrogen peroxide solution, and carrying out precipitation reaction to form Fe (OH) ₃ precipitate. The method can realize the combined extraction of the niobium and the iron in the Baiyunebo rare earth tailings, avoids the use of hydrofluoric acid, and has higher leaching rate of niobium.

Description

A method for combined extraction of ferroniobium from Bayan Obo rare earth tailings

Technical Field

The invention relates to the technical field of mineral recovery metallurgy, and in particular to a method for jointly extracting ferroniobium from Bayan Obo rare earth tailings.

Background Art

The Bayan Obo rare earth tailings are the products of Baotou Iron and Steel Mine after iron selection, rare earth selection and mixed flotation, and are the raw materials for the production of niobium concentrate. The mineral composition of Bayan Obo rare earth tailings is complex, mainly magnetite, pyrite, dolomite, fluorite and quartz, and contains a wide variety of niobium minerals and niobium minerals. Among them, the iron oxide content is 28.464%, the magnesium oxide content is 5.573%, and the calcium oxide content is 13.398%. Excessive iron, magnesium and calcium content affects the extraction of niobium. The niobium oxide content is 0.10%, which exceeds the boundary grade of niobium oxide by 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 tailings pond to burst, which is very dangerous. The problem of reasonable recycling of tailings remains to be solved.

The prior art only has methods for extracting and recovering niobium from the Bayan Obo rare earth ore, but no methods for recovering and treating the Bayan Obo rare earth tailings. When the prior method for extracting niobium from the Bayan Obo rare earth ore is used to extract niobium from the Bayan Obo rare earth tailings, the niobium extraction efficiency is low. In addition, the prior art uses a mixed leaching of high-concentration hydrofluoric acid and sulfuric acid. During the leaching process, hydrofluoric acid is easily volatile when heated, which pollutes the environment and harms human health. Hydrofluoric acid is easily corroded by equipment, which increases the cost of extracting niobium. In addition, the prior method can only extract niobium, but does not recover other metals, and the recovery efficiency is low.

Summary of the invention

In view of the above analysis, the present invention aims to provide a method for the combined extraction of niobium iron from the 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 recovered, resulting in low recovery efficiency; (2) hydrofluoric acid pollutes the environment, harms human health and corrodes equipment; (3) the efficiency of niobium extraction is low.

The present invention provides a method for jointly extracting ferroniobium from Bayan Obo rare earth tailings, the method comprising:

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): The acid wash solution and the raffinate are mixed, the pH is adjusted to 3-4.5, and then a hydrogen peroxide solution is added to perform a precipitation reaction to form a Fe(OH) ₃ precipitate.

Preferably, in step (1), dilute hydrochloric acid is used for pickling.

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

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

Preferably, the pickling temperature is 60-90°C.

Preferably, the pickling time is 1-1.5h.

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

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

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

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

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

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

2. The method of ammonium sulfate-enhanced sulfuric acid roasting-fluoride salt two-stage leaching in the present invention can effectively improve the niobium extraction efficiency in the Bayan Obo rare earth tailings. Sulfuric acid roasting destroys the mineral structure and releases the niobium element. Ammonium sulfate-enhanced sulfuric acid roasting allows fluoride ions to easily complex with niobium to form NbF ₆ ^- and NbOF ₅ ^2- , allowing niobium ions to enter the leachate, thereby increasing the leaching rate (also called extraction rate) of niobium, thereby improving the niobium extraction efficiency. In addition, the present invention does not use hydrofluoric acid, thereby reducing environmental pollution and the harm caused by hydrofluoric acid.

3. In the Bayan Obo rare earth tailings of the present invention, the content of niobium is low and the content of silicon oxide is high. The niobium in silicon oxide cannot be leached out by sulfuric acid leaching in the existing method alone, and the existing hydrofluoric acid leaching will pollute the environment. The present invention adds fluoride ions during the water leaching process. On the one hand, the fluoride ions destroy silicates in the acidic solution and release ^the niobium contained in the silicates. On the other hand, the fluoride ions and niobium are easily complexed to form _NbF6- and ^NbO52- , so that the niobium ions enter the leachate _and the leaching rate of niobium is improved. The reason why fluoride salts are not added in step (1) is that fluoride salts react easily with strong acids (concentrated sulfuric acid) to generate hydrofluoric acid, which volatilizes under high temperature conditions. This not only fails to destroy the silicate mineral structure, but also causes environmental pollution.

In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

FIG1 is a flow chart of the method for jointly extracting ferroniobium from Bayan Obo rare earth tailings of the present invention.

DETAILED DESCRIPTION

The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

The present invention provides a method for jointly extracting ferroniobium from Bayan Obo rare earth tailings, as shown in FIG1 , the method comprising:

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): The acid wash solution and the raffinate are mixed, the pH is adjusted to 3-4.5, and then a hydrogen peroxide solution is added to perform a precipitation reaction to form a Fe(OH) ₃ precipitate.

Compared with the prior art, the method of the present invention extracts niobium from the Bayan Obo rare earth tailings by ammonium sulfate-enhanced sulfuric acid roasting-fluoride salt two-stage leaching, and extracts iron by precipitation reaction of the pickling solution and the raffinate, thereby realizing the combined extraction of niobium and iron from the Bayan Obo rare earth tailings with high recovery efficiency.

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

It should be noted that the Bayan Obo rare earth tailings are the products of Baotou Iron and Steel Mine after iron and rare earth selection and mixed flotation. Its components include fluorite, quartz, magnetite and dolomite. The specific chemical composition is shown in Table 1 below.

The method of the invention is applicable to the Bayan Obo rare earth tailings. The Bayan Obo rare earth tailings have a low niobium content and a high silicon oxide content. The niobium in the silicon oxide cannot be leached only by sulfuric acid leaching in the existing method, and the existing hydrofluoric acid leaching will pollute the environment. The invention adds fluoride ions during the water leaching process. On the one hand, the fluoride ions destroy silicates and release niobium contained in the silicates. On the other hand, the fluoride ^ions are easily complexed with niobium ^to form _NbF6- and _NbOF52- , so that niobium ions enter the leaching solution, thereby improving the leaching rate of niobium.

In order to initially extract iron from the tailings, and to avoid the generation of insoluble sulfates during the ammonium sulfate-sulfuric acid roasting process, and to avoid the violent reaction of sulfuric acid and carbonates, and the danger of overflowing the pot, the present invention firstly pickles the Bayan Obo rare earth tailings to remove carbonate impurities in the Bayan Obo rare earth tailings, improve the subsequent niobium leaching efficiency, and initially leach iron into a dilute hydrochloric acid solution. The carbonate impurities include carbonate forms of iron, calcium, magnesium, aluminum and other ions.

Illustratively, in step (1), the pickling is performed using dilute hydrochloric acid.

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

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.

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

Exemplarily, the pickling time is 1-1.5h.

Specifically, before pickling the Bayan Obo rare earth tailings, the Bayan Obo rare earth tailings are first sieved through an 80-mesh sieve to remove leaves, small stones and other debris in the Bayan Obo rare earth tailings, and then the sieved material is dried at 100-120° C. for 4-5 hours.

The method of the invention is applicable to the Bayan Obo rare earth tailings. The Bayan Obo rare earth tailings have a low niobium content and a high silicon oxide content. The niobium in the silicon oxide cannot be leached only by sulfuric acid leaching in the existing method, and the existing hydrofluoric acid leaching will pollute the environment. The invention adds fluoride ions during the water leaching process. On the one hand, the fluoride ions destroy silicates and release niobium contained in the silicates. On the other hand, the fluoride ^ions are easily complexed with niobium ^to form _NbF6- and _NbOF52- , so that niobium ions enter the leaching solution, thereby improving the leaching rate of niobium.

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.

For example, in step (2), ammonium sulfate is first added to the Bayan Obo rare earth tailings, and after the Bayan Obo rare earth tailings and ammonium sulfate are mixed, 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.

Illustratively, in step (2), the temperature of the initial leaching is 260-300°C, such as 270°C, 280°C, or 290°C.

Exemplarily, in step (2), the initial leaching time is 2.0-2.5 h, such as 2.1 h, 2.2 h, 2.3 h, 2.4 h.

Exemplarily, after the initial leaching is completed, the sample is taken out and cooled to room temperature.

Exemplarily, in step (2), the mass ratio of the Bayan Obo rare earth tailings to the fluoride salt is 1:0.15-0.25. If there is too much fluoride salt, sodium fluoride will be wasted and too many fluoride ions will be produced, which are difficult to handle. If there is too little fluoride salt, the niobium extraction rate will be reduced and niobium cannot be fully extracted.

In the present invention, in step (2), fluoride ions destroy silicates in an acidic solution, thereby releasing niobium contained in the silicates.

For example, in step (2), after the mixture after the initial leaching is mixed with fluoride salt and water, the pH of the mixture is adjusted to 1.5-1.8, for example, pH 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.

Specifically, fluoride salt is first added to the mixture after the primary leaching, water is added after mixing evenly, and then a pH adjuster is added to adjust the pH of the solution.

Illustratively, the pH of the mixture is adjusted using dilute sulfuric acid and/or sodium hydroxide.

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

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

Exemplarily, in step (2), the secondary leaching time is 1-2 hours.

Illustratively, in step (2), stirring is performed during the secondary leaching process at a stirring speed of 300-500 r/min.

Illustratively, in step (2), the fluoride salt is sodium fluoride.

Illustratively, in step (2), extracting niobium from the obtained filtrate comprises: fixing the volume of the filtrate to 500 mL, concentrating the fixed niobium solution by 50 times, placing the concentrate and MIBK into a separatory funnel, shaking and then standing until an organic phase and an aqueous phase are stably separated in the separatory funnel, and separating the organic phase; back-extracting niobium from the organic phase, taking the organic phase and 0.5 mol/L sulfuric acid and placing them into a separatory funnel, shaking the separatory funnel, and extracting the aqueous phase after the aqueous phase and the organic phase are completely separated, and the aqueous phase is obtained. The aqueous phase is a niobium-containing solution.

Exemplarily, the volume ratio of the concentrate to MIBK is 1:1-2.

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

Illustratively, in step (3), adjusting the pH to 3-4.5 comprises: first adding 5-7 mol/L NaOH solution to adjust the pH to 2-2.5, and then adding 1-2 mol/L Na ₂ CO ₃ solution to adjust the pH to 3-4.5.

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

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

For example, 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.

Exemplarily, step (3) includes placing the precipitate in a muffle furnace and calcining it at 600-700° C. for 1-2 hours in order to remove water from the precipitate.

The method for combined extraction of ferroniobium from Bayan Obo rare earth tailings of the present invention is further illustrated below by means of specific examples.

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

Table 1

Components _Na2O MgO Al ₂ O ₃ SiO ₂ CaO _TiO2 MnO _{Fe2O3 ​ Nb2O5 ​} Wt.% 2.28 5.57 1.74 19.17 13.40 0.78 1.40 28.50 0.10

Example 1

This embodiment provides a method for jointly extracting ferroniobium from Bayan Obo rare earth tailings, the method comprising:

(1) Pretreatment: The Bayan Obo rare earth tailings were screened through an 80-mesh sieve to remove leaves, small stones and other debris from the Bayan Obo rare earth tailings, and the screened material was placed in a tray and dried at 100°C for 4 hours.

(2) Hydrochloric acid pickling: Take the Bayan Obo rare earth tailings and put them into a round-bottom flask. Add 2 mol/L hydrochloric acid at a liquid-to-solid ratio of 7:1. After connecting the round-bottom flask to a condensation reflux device, place it in a water bath at a temperature of 70°C. The rotor speed is 400 r/min and the pickling time is 1.2 h.

(3) Filtration and 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 liquid.

The removal rates of iron, magnesium, calcium and aluminum in the Bayan Obo rare earth tailings after pickling were detected and calculated by XRF, and they were 29.51%, 64.76%, 66.85% and 49.09% respectively. The recovery rate of niobium was 86.84%, which refers to the ratio of the remaining niobium in the tailings after pickling to the niobium in the tailings before pickling.

(4) Ammonium sulfate-enhanced sulfuric acid roasting and primary leaching: 2 g of tailings after acid washing are placed in a glass quartz crucible, and 0.6 g of ammonium sulfate and 2.5 mL of 98% concentrated sulfuric acid are added (the ratio of the mass of tailings to the mass of ammonium sulfate and the volume of concentrated sulfuric acid is 1:0.3:1.25). The tailings are first mixed with ammonium sulfate and then with concentrated sulfuric acid. The glass quartz crucible is placed in a muffle furnace at 290°C and roasted for 2 hours. After the roasting is completed, the quartz glass crucible is taken out and cooled to room temperature.

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

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

Detection of niobium extraction rate: The niobium content in the filtrate after the secondary leaching was detected by ICP-MS and the niobium leaching rate (extraction rate) was calculated to be 82%. The leaching rate is the ratio of the niobium content in the filtrate after the secondary leaching to the niobium content in the tailings before the primary leaching.

(7) Extraction of niobium: The filtrate was fixed to 500 mL, and the niobium solution was concentrated 50 times. The concentrated solution and MIBK (volume ratio of 1:1) were placed in a separatory funnel. The separatory funnel was shaken for 3 minutes. After the shaking, the separatory funnel was left to stand until the organic phase (extract solution) and the aqueous phase (raffinate) were stably separated in the separatory funnel to separate the organic phase. The niobium in the organic phase was extracted by back-extracting the organic phase and the organic phase and 0.5 mol/L sulfuric acid were placed in a separatory funnel in a volume ratio of 1:4. The separatory funnel was shaken for 5 minutes until the aqueous phase and the organic phase were completely separated. The aqueous phase was extracted and the niobium content was detected.

The niobium in the solution was extracted with MIBK, and the extraction rate reached 87.2%. The niobium was stripped with 0.5 mol/L sulfuric acid solution, and the dissolution rate of niobium was almost 100%.

(8) mixing the pickling solution and the raffinate, adding 5 mol/L NaOH solution to the mixed solution to adjust the pH value of the mixed solution to 2, and then adding 1 mol/L Na ₂ CO ₃ to adjust the pH value of the mixed solution to 3;

Add 25% H ₂ O ₂ solution to the mixed solution, 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 roast it at 600℃ for 1h.

The iron extraction rate is 45%, and the iron extraction rate is the ratio of the iron content in the product after iron extraction roasting to the iron content in the tailings before acid washing.

Example 2

This example provides the effect of the amount of ammonium sulfate added on the niobium extraction rate, and adopts a method for jointly extracting niobium iron from Bayan Obo rare earth tailings similar to Example 1, except that the amount of ammonium sulfate added is 0.1g, 0.2g, 0.4g, 0.5g, 0.6g, 0.7g, and 0.8g, respectively.

Table 2

The 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%

It can be seen from the data in Table 2 and Example 1 that when the amount of ammonium sulfate added 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 is maintained above 76%.

Example 3

This example provides the effect of the amount of concentrated sulfuric acid added on the niobium extraction rate, and adopts a method similar to Example 1 for the combined extraction of ferroniobium from the Bayan Obo rare earth tailings, except that the solid-liquid ratio (g/mL) of the tailings to the concentrated sulfuric acid is 1:0.25, 1:0.5, 1:0.75, 1:1, and 1:1.5, respectively. The results are shown in Table 3.

Table 3

It can be seen from the data in Table 3 and Example 1 that when the solid-liquid ratio of tailings to concentrated sulfuric acid is 1:1-1.5, the final leaching rate of niobium can reach more than 78%.

Example 4

This example provides the effect of roasting temperature on niobium extraction rate, using a method similar to Example 1 for combined extraction of niobium iron from Bayan Obo rare earth tailings, except 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.

Table 4

Calcination temperature 200℃ 230℃ 260℃ 280℃ 300℃ 320℃ Niobium leaching rate 67% 64% 71% 82% 82% 29%

It can be seen from the data in Table 4 and Example 1 that when the roasting temperature is between 260 and 300°C, the niobium extraction rate reaches more than 70%, and when the roasting temperature is between 260 and 300°C, the niobium extraction rate reaches more than 71%.

Example 5

This example provides the effect of roasting time on niobium extraction rate, using a method similar to Example 1 for combined extraction of ferroniobium from Bayan Obo rare earth tailings, except that the roasting times are 0.5h, 1.0h, 1.5h, and 2.5h, respectively. The results are shown in Table 5.

Table 5

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

It can be seen from the data in Table 5 and Example 1 that when the roasting time exceeds 2 hours, the niobium extraction rate remains substantially unchanged. Therefore, the preferred roasting time of the present invention is 2-2.5 hours.

Example 6

This example provides the effect of the amount of sodium fluoride added during the water leaching process on the niobium extraction rate. A method similar to Example 1 is used to jointly extract ferroniobium from the Bayan Obo rare earth tailings, except that the amount of sodium fluoride added is 0.1 g, 0.2 g, 0.4 g, and 0.5 g, respectively. The results are shown in Table 6.

Table 6

Sodium fluoride dosage 0.1g 0.2g 0.4g 0.5g Niobium leaching rate 13% 31% 82% 82%

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

Example 7

This example provides the effect of pH value on niobium extraction rate during water leaching, and adopts a method for combined extraction of niobium iron from Bayan Obo rare earth tailings similar to Example 1, except that the pH value is adjusted by dripping sodium hydroxide solution and sulfuric acid solution, and the pH value of the leaching solution is adjusted to 2.0.

The niobium leaching rate in this example is 67%.

Example 8

This example provides the effect of the secondary leaching temperature on the niobium extraction rate, and adopts a method for combined extraction of niobium iron from Bayan Obo rare earth tailings similar to that of Example 1, except that the secondary leaching temperature is 50°C.

The niobium leaching rate in this example is 68%.

Example 9

This embodiment provides the effect of the amount of dilute hydrochloric acid used on the iron extraction rate, and adopts a method for jointly extracting niobium iron from the Bayan Obo rare earth tailings similar to that of Example 1, except that in step (2), the liquid-to-solid ratio of dilute hydrochloric acid to the Bayan Obo rare earth tailings is 3:1.

The iron extraction rate in this example was 39%.

Example 10

This example provides the effect of the amount of _H2O2 solution on the _iron extraction rate. A method similar to Example 1 is used to jointly extract niobium iron from Bayan Obo rare earth tailings, except that the volume ratio of the mixed solution of the pickling solution and the raffinate to the hydrogen peroxide solution is 20:0.5.

The iron extraction rate in this example is 35%.

Comparative Example 1

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

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims (8)

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), adjusting the pH to 3-4.5 comprises: first adding 5-7 mol/L NaOH solution to adjust the pH to 2-2.5, and then adding 1-2 mol/L _{Na2CO3 solution} to adjust the pH 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.