Method for recovering fluorine in tailings containing fluorine, tantalum and niobium

Abstract

The invention provides a method for recovering fluorine in tailings containing fluorine, tantalum and niobium. The recovery method comprises the following steps: mixing and leaching the fluorine-containing tantalum-niobium ore tailings and a sulfuric acid solution, and carrying out solid-liquid separation to obtain a leachate; mixing and reacting a reducing agent with the leaching solution to reduce iron ions in the leaching solution into ferrous ions, so as to obtain an extraction material solution; mixing the extraction feed liquid with an organic phase, carrying out extraction treatment, and carrying out phase splitting to obtain a fluorine-containing extraction liquid; the organic phase comprises trioctylamine, an additive and a diluent; and mixing the fluorine-containing extraction liquid with an alkali solution, carrying out reverse extraction treatment, and carrying out phase splitting to obtain a fluorine-containing reverse extraction liquid and a no-load organic phase.

Description

Technical Field

[0001] This application relates to the field of tantalum-niobium ore tailings recycling technology, and in particular to a method for recovering fluorine from fluorine-containing tantalum-niobium tailings. Background Technology

[0002] Tantalum and niobium are both rare metals and important strategic reserve resources. They have excellent physical and chemical properties and have been widely used in electronics, steel, aerospace, chemical industry and nuclear industry.

[0003] Currently, tantalum and niobium smelting methods include the hydrofluoric acid process, the sulfuric acid process (high temperature), the hydrofluoric acid-sulfuric acid process, the alkali fusion process, and the alkaline solution process; among these, the hydrofluoric acid-sulfuric acid process is the most widely used. The main process of the hydrofluoric acid-sulfuric acid process involves the decomposition of tantalum and niobium ore by hydrofluoric acid and sulfuric acid followed by slurry extraction. This extraction process generates a large amount of tantalum and niobium tailings. These tailings are typically treated using mineral processing methods, sulfuric acid-alkali conversion methods, or water washing-drying-pyrometallurgical recovery of tin and rare earth elements. Because tantalum and niobium tailings contain a large amount of fluorine, regardless of whether hydrometallurgical processes or pyrometallurgical smelting are used for tin recovery, wastewater containing high levels of fluorine and iron, or fluorine-containing slag, will inevitably be generated. Due to the corrosive nature of fluoride, high levels of fluoride ions in wastewater can harm the environment and human health. Currently, fluoride removal from wastewater is usually achieved by precipitating calcium fluoride with lime. However, lime also precipitates sulfate ions, resulting in low purity of the precipitated calcium fluoride slag, which becomes hazardous waste and still requires treatment. In pyrometallurgical tin smelting, fluoride enters the smelting slag, making the composition even more complex, and fluoride cannot be efficiently utilized.

[0004] Therefore, it is necessary to provide a method for recovering fluorine from tantalum-niobium ore tailings to produce a fluorine product with better purity, so as to reduce the environmental impact of tantalum-niobium ore tailings and achieve efficient utilization of resources. Summary of the Invention

[0005] Based on this, one or more embodiments of this application provide a method for recovering fluorine from fluorinated tantalum-niobium tailings that can efficiently recover fluorine.

[0006] According to a first aspect of the embodiments of this application, a method for recovering fluorine from fluorine-containing tantalum-niobium tailings is provided, comprising the following steps:

[0007] The tailings of fluorine-containing tantalum-niobium ore are mixed with sulfuric acid solution and leached, and the leachate is obtained by solid-liquid separation.

[0008] The reducing agent is mixed with the leachate to react and reduce the iron ions in the leachate to ferrous ions, thereby obtaining the extraction solution.

[0009] The extraction solution is mixed with an organic phase for extraction treatment, and after phase separation, a fluorine-containing extract is obtained; the organic phase includes trioctylamine, additives, and diluents.

[0010] The fluorine-containing extract was mixed with an alkaline solution and subjected to back-extraction. After phase separation, a fluorine-containing back-extraction solution and a regenerated organic phase were obtained.

[0011] In some embodiments, the organic phase comprises, by volume percentage, 20%–30% trioctylamine, 20%–30% additives, and 40%–60% diluent.

[0012] In some embodiments, the diluent is selected from one or more of kerosene, xylene, cyclohexane, and carbon tetrachloride; and / or,

[0013] The additive is selected from one or more of tributyl phosphate, sec-octanol and n-octanol.

[0014] In some embodiments, the reducing agent includes iron; and / or,

[0015] The concentration of the solute in the sulfuric acid solution is 10 g / L to 150 g / L; and / or,

[0016] The ratio of the sulfuric acid solution to the tantalum-niobium ore tailings added is (1 mL~5 mL): 1 g; and / or,

[0017] The leaching temperature is 55℃~65℃; and / or,

[0018] The extraction process is performed at a temperature of 20℃~40℃; and / or,

[0019] The pH value of the extraction solution is 1~4.

[0020] In some embodiments, after the extraction process and before the back-extraction process, the following steps are further included:

[0021] The fluorine-containing extract is then washed.

[0022] In some embodiments, the washing process is a multi-stage countercurrent washing process, wherein the number of stages in the multi-stage countercurrent washing process is 2 to 3.

[0023] In some embodiments, the washing process uses a sulfuric acid solution.

[0024] In some embodiments, the concentration of the sulfuric acid solution is 0.05 mol / L to 0.15 mol / L.

[0025] In some embodiments, the extraction process is a multi-stage countercurrent extraction, wherein the number of stages in the multi-stage countercurrent extraction is 2 to 4; and / or,

[0026] The back-extraction process is a multi-stage countercurrent back-extraction, and the number of stages in the multi-stage countercurrent back-extraction is 2 to 4.

[0027] In some embodiments, the recycling method further includes the following steps:

[0028] The unloaded organic phase is subjected to acidification and regeneration treatment; and / or,

[0029] The back-extraction solution is then purified.

[0030] Compared with traditional technologies, this application has the following advantages:

[0031] In the recycling method of this application, fluorine-containing tantalum-niobium ore tailings are first mixed with sulfuric acid solution to enhance fluorine leaching, forming a solution containing Fe. 3+ Fe 2+ F - The plasma leaching solution was subjected to reduction treatment to remove Fe from the leaching solution. 3+ Reduced to Fe 2+ To reduce Fe 3+ The effect on the extraction process avoids the need for pretreatment of iron before extraction; at the same time, the use of the organic phase with the specific formulation of this application can remove F from the leachate. - The fluorine salt solution is extracted into the organic phase under the condition of a large amount of iron ions, and then back-extracted to obtain a fluorine salt solution. The back-extracted fluorine salt solution is then purified to obtain fluorine products, thereby realizing the separation and recycling of fluorine from tantalum, niobium, tin, iron and rare earth elements in tantalum and niobium ore tailings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the specific embodiments of this application, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0033] Figure 1 This is a schematic diagram of the process for recycling tantalum-niobium ore tailings in an embodiment of this application;

[0034] Figure 2 This is a schematic diagram of the extraction process for tantalum-niobium ore tailings in an embodiment of this application. Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] 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 this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.

[0037] The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0038] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0039] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0040] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0041] In this document, terms such as “preferred,” “better,” “more suitable,” and “ideal” are merely used to describe implementation methods or examples that achieve better results, and should be understood not to limit the scope of protection of this application.

[0042] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0043] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0044] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0045] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0046] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0047] Some embodiments of this application provide a method for recovering fluorine from fluorine-containing tantalum-niobium tailings, comprising the following steps:

[0048] S10. The tailings of fluorine-containing tantalum-niobium ore are mixed with sulfuric acid solution and leached, and the leachate is obtained by solid-liquid separation.

[0049] S20. The reducing agent is mixed with the leachate to react, so that the iron ions in the leachate are reduced to ferrous ions, and an extraction solution is obtained.

[0050] S30. The extractant solution is mixed with the organic phase for extraction treatment. After phase separation, a fluorine-containing extract is obtained. The organic phase includes trioctylamine, additives and diluents.

[0051] S40. The fluorine-containing extract is mixed with an alkaline solution and subjected to back-extraction. After phase separation, a fluorine-containing back-extraction solution and an empty organic phase are obtained.

[0052] In some embodiments, S30 further includes raffinate after phase separation.

[0053] In the recycling method of this application, tantalum-niobium ore tailings are first mixed with an acidic solution to form a solution containing Fe. 3+ Fe 2+ F - The plasma leaching solution was subjected to reduction treatment to remove Fe from the leaching solution. 3+ Reduced to Fe 2+ To reduce Fe 3+ The effect on the extraction process; simultaneously, by using the organic phase with the specific formulation of this application, the F in the leachate can be removed. - Extracted into the organic phase and then chemically back-extracted from F - A fluorine-containing salt solution was extracted, thereby achieving the separation and recycling of fluorine from tantalum and niobium ore tailings.

[0054] In some embodiments, the organic phase comprises, by volume percentage, 20%–30% trioctylamine, 20%–30% additives, and 40%–60% diluent.

[0055] It is understandable that trioctylamine, as an organic phase, interacts with F. - The additives can improve the phase separation rate, prevent the formation of a third phase and emulsification; the diluents can regulate the concentration of the organic phase, change the density of the organic phase, improve the phase separation rate, and dissolve the extracts extracted into the organic phase.

[0056] In some of these embodiments, trioctylamine is selected from Alamine 336.

[0057] As an example, the volume percentage of trioctylamine in the organic phase can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any value within the range of any two of the above points.

[0058] Furthermore, the volume percentage of trioctylamine in the organic phase is 22%~28%; even further, the volume percentage of trioctylamine in the organic phase is 25%.

[0059] As an example, the volume percentage of the additive in the organic phase can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any value within the range formed by any two of the above points.

[0060] Furthermore, the volume percentage of additives in the organic phase is 22% to 28%; even further, the volume percentage of additives in the organic phase is 25%.

[0061] As an example, the volume percentage of diluent in the organic phase is 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, or any value within the range formed by any two of the above points.

[0062] Furthermore, the volume percentage of the diluent in the organic phase is 48% to 52%; even further, the volume percentage of the diluent in the organic phase is 50%.

[0063] In some embodiments, the diluent is selected from one or more of kerosene, xylene, cyclohexane, and carbon tetrachloride. Optionally, the diluent is selected from kerosene.

[0064] In some embodiments, the additive is selected from one or more of tributyl phosphate (TBP), 2-octanol, and n-octanol. Optionally, the additive is selected from tributyl phosphate.

[0065] In some embodiments, in S10, the concentration of the solute in the sulfuric acid solution is 10 g / L to 150 g / L. As an example, the concentration of the solute in the sulfuric acid solution can be 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, or any value within the range formed by any two of the above values.

[0066] In some embodiments, in S10, the ratio of sulfuric acid solution to tantalum-niobium ore tailings added is (1 mL to 5 mL): 1 g. As an example, the ratio of sulfuric acid solution to tantalum-niobium ore tailings added can be 1 mL: 1 g, 2 mL: 1 g, 3 mL: 1 g, 4 mL: 1 g, 5 mL: 1 g, or any value within the range of any two of the above ratios.

[0067] It is understandable that the tailings of tantalum and niobium ore formed after smelting tantalum and niobium using the hydrofluoric acid-sulfuric acid process already contain sulfate ions. Therefore, leaching the tailings with sulfuric acid solution can reduce the introduction of additional impurities.

[0068] In some embodiments, in S10, the leaching temperature is 55°C to 65°C. As an example, the leaching temperature can be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, or any value within the range formed by any two of the above points.

[0069] It is understandable that tantalum-niobium ore tailings contain Fe. 3+ Fe 2+ Mn 2+ SO4 2- F - Plasma is leached using sulfuric acid solution at specific temperature conditions, which allows the aforementioned ions to fully dissolve into the leachate.

[0070] In some embodiments, in S20, the reducing agent includes iron. It should be noted that the reducing agent can be iron powder, iron filings, or other forms; this application does not impose any particular limitation on this.

[0071] In some embodiments, Fe in the leachate 3+ The molar mass ratio of the reducing agent to the reducing agent is (1.2~2):1.

[0072] It is understandable that iron can neutralize the Fe in the leachate. 3+ Reduced to Fe 2+ To improve the extraction of F from the leachate - The extraction efficiency. Specifically, the leachate obtained after sulfuric acid leaching is usually acidic, with a pH value between 1 and 4, and the Fe in the leachate... 3+ Precipitation begins at around pH 3, and the resulting precipitate may affect the extraction efficiency; meanwhile, Fe... 3+ Also with F - Complexation occurs, causing F - It cannot be separated by chemical extraction.

[0073] In some embodiments, the pH of the extraction feed solution is 1 to 4.

[0074] It is understandable that when the pH of the extraction solution is below 1, the concentration of H+ will be higher. + Will with F - This combination inhibits the dissociation of HF, thus allowing free F to bind and thus suppress the dissociation of HF. - The concentration decreased significantly; when the pH value was higher than 4, impurity elements in the leachate may precipitate, affecting the efficiency of chemical extraction.

[0075] In some embodiments, S30 further includes the following steps before using the organic phase for extraction: saponifying the organic phase with NaOH solution and then acidifying the organic phase with sulfuric acid solution.

[0076] Optionally, the concentration of the NaOH solution used for saponification is 2 mol / L; the concentration of the sulfuric acid solution used for acidification is 2 mol / L.

[0077] In the acidified organic phase, trioctylamine complexes with sulfuric acid solution to form R3NH·HSO4, which can react with F during the extraction process. - The reaction forms R3NH·F, thereby achieving the conversion of F - Extracted into the organic phase. Specific reactions include:

[0078] R3NH·HSO4(org)+F - (aq)=R3NH·F(org)+H + (aq)+SO4 2- (aq).

[0079] In some embodiments, the extraction temperature in S30 is 20°C to 40°C.

[0080] As an example, the extraction temperature can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, or any value within the range formed by any two of the above points.

[0081] In some embodiments, the extraction process is a multi-stage countercurrent extraction, with 2 to 4 stages. For example, the multi-stage countercurrent extraction can have 2, 3, or 4 stages.

[0082] Optionally, the countercurrent extraction time is 3 to 5 minutes. As an example, the countercurrent extraction time can be 3 minutes, 4 minutes, 5 minutes, or any value within the range formed by any two of the above points.

[0083] In some embodiments, the volume ratio of the organic phase to the aqueous phase in the extraction process is (1.5~2.5):1; optionally, it is 2:1.

[0084] In some embodiments, S30, after extraction and before back-extraction, includes the following step: washing the fluorine-containing extract.

[0085] In some embodiments, the solution used for the washing process is a sulfuric acid solution.

[0086] In some embodiments, the volume ratio of the organic phase to the aqueous phase in the washing process is (9~11):1; optionally, it is 10:1.

[0087] In some embodiments, the washing process is a multi-stage countercurrent washing process, with 2 to 3 stages. Optionally, the washing process time is 3 to 5 minutes. As an example, the washing process time can be 3 minutes, 4 minutes, 5 minutes, or any value within the range formed by any two of the above points.

[0088] Understandably, washing with sulfuric acid solution can effectively transfer impurities entrained in the organic phase into the aqueous phase, while F - It remains in the organic phase, thereby improving the F after chemical back-extraction. - Purity.

[0089] In some embodiments, the concentration of the sulfuric acid solution used in the washing process is 0.05 mol / L to 0.15 mol / L. As an example, the concentration of the sulfuric acid solution can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, or any value within the range formed by any two of the above values.

[0090] In this application, sodium hydroxide solution is used for back-extraction, which can react with R3NH·F to generate NaF, thereby achieving the removal of F. - The sample is back-extracted into the aqueous phase. Specific reactions include:

[0091] R3NH·F(org)+NaOH(aq)=R3NH·OH(org)+NaF(aq).

[0092] In some embodiments, the concentration of the sodium hydroxide solution in S40 is 1.5 mol / L to 2.5 mol / L; further, the concentration of the sodium hydroxide solution is 2 mol / L.

[0093] In some embodiments, the back-extraction process in S40 is a multi-stage countercurrent back-extraction, with 2 to 4 stages. As an example, the number of stages in the multi-stage countercurrent back-extraction can be 2, 3, or 4.

[0094] Optionally, the countercurrent extraction time is 3 to 5 minutes. As an example, the countercurrent extraction time can be 3 minutes, 4 minutes, 5 minutes, or any value within the range formed by any two of the above points.

[0095] In some embodiments, the volume ratio of the organic phase to the aqueous phase in the back-extraction process S40 is (1~5):1; optionally (1.5~2.5):1; and further optionally 2:1.

[0096] In some embodiments, the above-described method for recovering tantalum-niobium ore tailings further includes the following steps:

[0097] S50. The unloaded organic phase is subjected to acidification and regeneration treatment.

[0098] Optionally, in S50, the acid solution used in the acidification and regeneration process includes a sulfuric acid solution.

[0099] In some embodiments, the volume ratio of the organic phase to the aqueous phase in the acidification and regeneration process in S50 is (1~10):1, optionally (1.5~2.5):1; and further optionally 2:1.

[0100] Understandably, the unloaded organic phase can be re-entered into the extraction system after acidification and regeneration.

[0101] In some embodiments, the above-described method for recovering tantalum-niobium ore tailings further includes the following steps:

[0102] S60. The fluorine-containing back-extraction solution is subjected to impurity removal and purification, evaporation and crystallization, solid-liquid separation and drying in sequence to prepare industrial-grade sodium fluoride.

[0103] Understandably, the industrial-grade sodium fluoride prepared in the above manner conforms to the YS / T517-2009 standard.

[0104] In some embodiments, the impurity removal and purification steps include sequentially subjecting the fluoride-containing back-extraction solution to activated carbon adsorption and filtration. Further, after filtration, the step of adjusting the pH of the back-extraction solution to 7-8 is included. Understandably, by adjusting the pH of the back-extraction solution, it is possible to reduce strong alkaline corrosion in subsequent equipment and reduce hydroxide impurities in the product.

[0105] Furthermore, the activated carbon adsorption process includes adding a small amount of powdered activated carbon to the solution and stirring for 30-60 minutes. Understandably, activated carbon can effectively adsorb organic impurities and pigments.

[0106] Furthermore, the filtration steps include: using a plate and frame filter press, vacuum filtration, or precision filter bags to thoroughly filter out the activated carbon and the impurities it adsorbs, obtaining a clear and transparent sodium fluoride solution.

[0107] Understandably, the solution obtained from back-extraction may contain trace amounts of trioctylamine, metal ion impurities, or other organic matter, which can affect the purity and color of the final crystals. Removal and purification can improve the purity and color of the crystals.

[0108] In some embodiments, the evaporation crystallization step includes: heating and concentrating the solution under reduced pressure using a rotary evaporator, a multi-effect evaporator, or a glass-lined reactor with a stirrer; transferring the concentrated hot saturated solution to a crystallization tank, starting slow stirring, and then allowing it to cool naturally or be forcibly cooled to room temperature by circulating cooling water.

[0109] Understandably, reducing pressure lowers the boiling point, saves energy, and prevents bumping. Since the solubility of sodium fluoride decreases with decreasing temperature, crystals will gradually precipitate out during cooling.

[0110] Understandably, evaporation and crystallization can remove most of the water, causing the solution to become supersaturated until it is concentrated to near saturation concentration (about 4%) or even higher.

[0111] In some embodiments, a small amount of pre-prepared, high-purity, microcrystalline sodium fluoride is added when the solution reaches near its saturation point. Understandably, these crystals provide a "template" for solute molecules to attach to, promoting the formation of large, well-defined, uniform crystals, rather than fine powder, which is beneficial for subsequent filtration and washing.

[0112] Maintaining slow stirring and a certain residence time during crystallization can result in larger and more complete crystals.

[0113] Understandably, during solid-liquid separation, the crystal surface is washed with a small amount of cold deionized water or alcohol to remove the mother liquor adhering to the crystal surface; using a cold solvent can minimize the dissolution loss of the crystal.

[0114] In some embodiments, the drying method is either electrically heated air drying or vacuum drying. Understandably, vacuum drying can efficiently remove moisture at lower temperatures, preventing the crystals from agglomerating or decomposing due to heat.

[0115] In some embodiments, after drying, the process further includes packaging and storing the sodium fluoride.

[0116] The method for recovering fluorine from fluorinated tantalum-niobium tailings disclosed in this application can effectively separate and recover fluorine from tantalum-niobium ore tailings, thereby reducing the harm of fluorine to the environment and human health. Simultaneously, the recovered fluorine can be applied to multiple industrial fields, such as aluminum electrolysis (cryolite), steelmaking (fluorite slagging agent), refrigerants (Freon, etc.), chemical raw materials (polytetrafluoroethylene), electrolytes (lithium hexafluorophosphate), electronic products, fluororubber, fluorine coatings, and pharmaceuticals; thus achieving resource reuse.

[0117] The present application will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present application. Unless otherwise specified, the raw materials involved in the following specific embodiments are all commercially available, the instruments used are all commercially available, and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0118] Example 1

[0119] Reference Figure 1 and Figure 2 The process shown here is for the recovery and treatment of tailings obtained from the hydrofluoric acid-sulfuric acid process for smelting tantalum and niobium. The main chemical components and contents of the tailings are shown in Table 1. The specific steps include the following:

[0120] Table 1

[0121]

[0122] (1) Weigh 2000g of dried tantalum-niobium tailings sample into a beaker, add 4000mL of H2SO4 solution heated to 60℃ with a concentration of 100g / L; maintain 60℃, stir for 2h, filter to obtain 2300mL of leachate, and detect Fe in the leachate. 3+ After determining the concentration, iron powder was added at 1.2 times the theoretical amount, and the mixture was stirred and reacted for 2 hours. After filtration, the aqueous phase of the extract was obtained.

[0123] (2) Preparation of organic phase: by volume percentage, it contains 25% Alamine 336, 25% tributyl phosphate and 50% kerosene; the above organic phase is saponified with 2 mol / L NaOH solution and then acidified with 2 mol / L sulfuric acid to serve as the organic phase.

[0124] Take 50 mL of the above organic phase and extract it at 25 °C with a phase ratio of O / A of 2:1 using a three-stage countercurrent extraction method. The extraction time is 5 min and the phase separation time is 5 min.

[0125] (3) Use 0.1 mol / L sulfuric acid as washing solution, with a ratio of O / A of 10:1. Perform two-stage countercurrent washing for 5 min and phase separation time of 5 min.

[0126] (4) Use 2 mol / L NaOH solution as the back-extraction agent, with a ratio of O / A of 2:1. Perform three-stage countercurrent back-extraction, with a back-extraction time of 5 min and a phase separation time of 5 min.

[0127] (5) After the back-extraction is completed, acidify with 2 mol / L sulfuric acid solution at a ratio of O / A = 5:1 to realize the recycling of organic phase solution.

[0128] (6) Adjust the pH of the back-extracted sodium fluoride solution to 7, add 0.5g of activated carbon, stir for 45min, and filter. Pour the filtrate into a rotary evaporator and concentrate it to 20% of the original volume. Pour the concentrate into a crystallization basin, and when the temperature drops to 50℃, add 0.5g of sodium fluoride seed crystals, stir slowly, and let stand for 12h; then filter, wash, and dry to obtain a white powder as the product sodium fluoride (meeting the standard of YS / T517-2009 Grade III).

[0129] Example 2

[0130] The example is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, by volume percentage, the organic phase used in Example 2 includes 20% Alamine 336, 25% tributyl phosphate and 55% kerosene.

[0131] Example 3

[0132] It is basically the same as Example 1, except that the extraction temperature in step (2) is different. Specifically, the extraction temperature in Example 3 is 15°C.

[0133] Example 4

[0134] It is basically the same as Example 1, except that the extraction temperature in step (2) is different. Specifically, the extraction temperature in Example 4 is 40°C.

[0135] Example 5

[0136] The example is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, by volume percentage, the organic phase used in Example 5 includes 30% Alamine 336, 25% tributyl phosphate and 45% kerosene.

[0137] Comparative Example 1

[0138] It is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, the organic phase used in Comparative Example 1 is Alamine 336.

[0139] Comparative Example 2

[0140] The comparison is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, by volume percentage, the organic phase used in Comparative Example 2 includes 25% Alamine 336 and 75% kerosene.

[0141] Comparative Example 3

[0142] The comparison is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, by volume percentage, the organic phase used in Comparative Example 3 includes 25% tributyl phosphate and 75% kerosene.

[0143] Comparative Example 4

[0144] The example is basically the same as Example 1, except that the formulation of the organic phase in step (2) is different; specifically, by volume percentage, the organic phase used in Example 5 includes 25% triisooctylamine, 25% tributyl phosphate and 50% kerosene.

[0145] In the above embodiments and comparative examples, F in the aqueous phase after extraction, washing, and back-extraction - The concentrations are shown in Table 1. The original solution corresponds to the F concentration in the aqueous extraction solution from step (1). - The concentration of F in the raffinate corresponds to the concentration of F in the first, second, and third stage extractions. - The concentration of F in the washing solution corresponds to the first and second stage washes. - The concentration of F in the extraction solution corresponds to the concentration of F in the first-stage, second-stage, and third-stage back-extraction solutions. - The concentration.

[0146] Table 1

[0147]

[0148] After chemical extraction, F - F was extracted into the organic phase, and the residual F in the aqueous phase (raffinate) - The amount of residual F in the aqueous phase is decreasing; after washing, the amount of residual F in the aqueous phase is decreasing. - It re-enters the organic phase, therefore F in the aqueous phase (washing liquid) - The concentration gradually decreased; after back-extraction, the F in the organic phase - The solution is extracted into the aqueous phase (back-extraction solution) to obtain the final fluoride-containing salt solution. Therefore, after multiple stages of back-extraction, the fluoride in the back-extraction solution is... - The concentration gradually increases.

[0149] As shown in the table above, the organic phase of Comparative Example 1 contains only trioctylamine, and severe emulsification and phase separation occur during the extraction process, making it impossible to effectively extract and recover F. - The organic phase of Comparative Example 2 did not contain any additives, and the organic phase of Comparative Example 3 did not contain any diluents. The final recovered F - The concentration was much lower than in Examples 1-5; in Comparative Example 4, triisooctylamine was used instead of Alamine 336, which reduced the extraction efficiency.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for recovering fluorine from fluorine-containing tantalum-niobium tailings, characterized in that, Includes the following steps: The tailings of fluorine-containing tantalum-niobium ore are mixed with sulfuric acid solution and leached, and the leachate is obtained by solid-liquid separation. The reducing agent is mixed with the leachate to react and reduce the iron ions in the leachate to ferrous ions, thereby obtaining the extraction solution. The extraction solution is mixed with an organic phase for extraction treatment, and after phase separation, a fluorine-containing extract is obtained; the organic phase includes trioctylamine, additives, and diluents. The fluorine-containing extract was mixed with an alkaline solution and subjected to back-extraction. After phase separation, a fluorine-containing back-extraction solution and an empty organic phase were obtained.

2. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to claim 1, characterized in that, The organic phase comprises, by volume percentage, 20%–30% trioctylamine, 20%–30% additives, and 40%–60% diluent.

3. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to claim 1, characterized in that, The diluent is selected from one or more of kerosene, xylene, cyclohexane, and carbon tetrachloride; and / or, The additive is selected from one or more of tributyl phosphate, sec-octanol and n-octanol.

4. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to any one of claims 1 to 3, characterized in that, The reducing agent includes iron; and / or, The concentration of the solute in the sulfuric acid solution is 10 g / L to 150 g / L; and / or, The ratio of the sulfuric acid solution to the tantalum-niobium ore tailings added is (1 mL~5 mL): 1 g; and / or, The leaching temperature is 55℃~65℃; and / or, The extraction process is performed at a temperature of 20℃~40℃; and / or, The pH value of the extraction solution is 1~4.

5. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to any one of claims 1 to 3, characterized in that, After the extraction process and before the back-extraction process, the following steps are also included: The fluorine-containing extract is then washed.

6. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to claim 5, characterized in that, The washing process is a multi-stage countercurrent washing process, and the number of stages in the multi-stage countercurrent washing process is 2 to 3.

7. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to claim 5, characterized in that, The solution used in the washing process is a sulfuric acid solution.

8. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to any one of claims 1-3 and 6-7, characterized in that, The concentration of the sulfuric acid solution is 0.05 mol / L to 0.15 mol / L.

9. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to any one of claims 1-3 and 6-7, characterized in that, The extraction process is a multi-stage countercurrent extraction, wherein the number of stages in the multi-stage countercurrent extraction is 2 to 4; and / or, The back-extraction process is a multi-stage countercurrent back-extraction, and the number of stages in the multi-stage countercurrent back-extraction is 2 to 4.

10. The method for recovering fluorine from fluorine-containing tantalum-niobium tailings according to any one of claims 1-3 and 6-7, characterized in that, The recycling method further includes the following steps: The unloaded organic phase is subjected to acidification and regeneration treatment; and / or, The back-extraction solution is then purified.

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