Membrane integrated tantalum and salt recovery method for pyrometallurgical tantalum wastewater and solid waste

Abstract

The invention relates to the technical field of comprehensive utilization of resources, and particularly discloses a method for recovering tantalum and salt from pyrometallurgy tantalum wastewater and solid waste through membrane integration, which comprises the following steps: classifying, crushing and grinding the pyrometallurgy tantalum solid waste, adding acid according to quality, introducing the pretreated tantalum-containing wastewater into a reaction container according to a ratio, and carrying out dissolved salt filtration; combining the dissolved solution, and recovering high-purity component salt through nanofiltration and crystallization evaporation; after adding an agent into a mixed membrane concentrated solution, carrying out plate-and-frame pressure filtration, carrying out acid leaching on a filter cake, regulating pH, precipitating, burning and recovering tantalum, regularly cleaning a nanofiltration membrane, and carrying out reverse osmosis on cleaning wastewater for recycling, so that the problems of low tantalum recovery rate, waste of salt resources, easy pollution and short service life of the membrane, large water resource consumption and low process dispersion efficiency in the traditional treatment are solved.

Description

Technical Field

[0001] This invention relates to the field of comprehensive resource utilization technology, specifically to a membrane-integrated method for the recovery of tantalum and salts from pyrometallurgical tantalum wastewater and solid waste. Background Technology

[0002] With the increasingly widespread application of pyrometallurgical tantalum in high-end fields such as electronics and aerospace, the amount of tantalum-containing solid waste and tantalum-containing wastewater generated during the production process is constantly increasing. These solid wastes and wastewaters not only contain recyclable tantalum resources, but are also rich in salt components such as fluorides and chlorides. Membrane separation technology is gradually being used for resource recovery, but existing processes are not well adapted to the co-treatment of solid waste and wastewater.

[0003] In traditional pyrometallurgical tantalum waste solid waste treatment, solid waste is often treated with mixed acid leaching, which does not distinguish the occurrence form of tantalum, resulting in large fluctuations in leaching rate; it is difficult to recover salt resources in the same way as wastewater treatment; membrane separation devices are prone to shortened lifespan due to colloid and scaling pollution, and lack system coordination design, resulting in problems such as low tantalum recovery rate, waste of salt resources, large water consumption, fragmented processes, and high maintenance costs.

[0004] Therefore, it is necessary to design a membrane-integrated method for the recovery of tantalum and salt from pyrometallurgical tantalum wastewater and solid waste, in order to solve the problems of insufficient solid waste leaching, low tantalum-salt separation efficiency, severe membrane fouling and short lifespan, inability to recycle water resources, waste of salt resources, and low efficiency of decentralized process treatment in existing technologies. Summary of the Invention

[0005] In view of this, the present invention proposes a membrane-integrated method for the recovery of tantalum and salt from pyrometallurgical tantalum wastewater and solid waste, in order to solve the problems of insufficient solid waste leaching, low tantalum and salt separation efficiency, severe membrane fouling and short lifespan, inability to recycle water resources, waste of salt resources, and low efficiency of decentralized process treatment in the prior art.

[0006] This invention proposes a membrane-integrated method for the recovery of tantalum and salts from pyrometallurgical tantalum wastewater and solid waste, comprising the following steps: Pyrometallurgical tantalum solid waste was classified and pretreated separately to obtain different powdered products. The different powdered products were added to the reaction vessels respectively, acid was added to each reaction vessel, and tantalum-containing wastewater was pretreated and then passed into each reaction vessel in proportion for salt filtration to obtain different solutions and mixed membrane concentrates. The different solutions are combined and then passed into a nanofiltration device for filtration. The filtered solution was subjected to crystallization and evaporation separation to obtain high-purity component salts; Add the reagent to the mixed membrane concentrate, stir, and then filter through a plate and frame filter press to obtain a filter cake; Acid is added to the filter cake, stirred and leached, filtered, and the pH of the filtrate is adjusted to 8-9 to generate a precipitate. The precipitate is then post-treated to obtain recovered tantalum. The cleaning solution is periodically passed into the nanofiltration device for cleaning, the cleaning wastewater is collected, and then passed into a reverse osmosis device for treatment to obtain recycled water.

[0007] Furthermore, the pyrometallurgical tantalum solid waste, after being crushed and ground, is processed through a 200-300 mesh sieve.

[0008] Furthermore, when adding acid to each reaction vessel: The added acid is either hydrochloric acid or hydrofluoric acid, and the solid-liquid ratio of the added acid to the powdered product is 1:5 to 1:10.

[0009] Furthermore, the pretreatment of the tantalum-containing wastewater is ultrasonic treatment, wherein the ultrasonic frequency of the ultrasonic treatment is 20-40kHz and the ultrasonic time is 10-15min.

[0010] Furthermore, before the reaction vessel undergoes salt filtration, the temperature is adjusted to 50-90℃, the stirring rate is adjusted to 200-300 r / min, and the pH is adjusted to 2.5-3.5.

[0011] Furthermore, the agent is 0.1%-0.3% polyacrylamide.

[0012] Furthermore, after stirring, the filter cake is obtained by plate and frame filtration: The stirring time is 10-15 min, and the pressure of the plate and frame filter press is 0.8-1.2 MPa.

[0013] Furthermore, acid is added to the filter cake, and during stirring, leaching, and filtration: The acid is 1-2 mol / L hydrochloric acid, the stirring leaching temperature is 60-70℃, and the leaching time is 1-1.5h.

[0014] Furthermore, the post-processing specifically includes: The precipitate was washed with deionized water 3-5 times to adjust the pH to 7, and then calcined at 800-1000℃ for 2-3 hours to obtain recovered tantalum.

[0015] Furthermore, the step of periodically passing the cleaning solution into the nanofiltration device for cleaning specifically involves: Clean the nanofiltration device online for 30-40 minutes every 15-20 days with a mixed solution of 0.3-0.5 mol / L citric acid and 0.1-0.2 mol / L EDTA.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention improves tantalum leaching efficiency by classifying, crushing, grinding, and acidifying pyrometallurgical tantalum solid waste, followed by pretreatment of tantalum-containing wastewater and subsequent salt filtration. This process adapts to different tantalum occurrence forms in solid waste. The combined solution is then separated by nanofiltration, crystallization, and evaporation to recover high-purity component salts, avoiding salt resource waste. After adding reagents and pressing the mixed membrane concentrate, the filter cake is acid-leached, pH-adjusted, precipitated, and calcined to efficiently recover tantalum, increasing the overall tantalum recovery rate. Regular cleaning of the nanofiltration membrane and reverse osmosis reuse of the cleaning wastewater extend membrane life and save water resources. Overall, this invention achieves synergistic recovery and resource recycling of tantalum and salts, solving the problems of dispersed processes and low resource utilization in traditional methods. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 The flowchart illustrates a method for membrane-integrated recovery of tantalum and salts from pyrometallurgical tantalum wastewater and solid waste, provided in an embodiment of the present invention. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] like Figure 1 As shown in some embodiments of this application, a membrane-integrated method for the recovery of tantalum and salts from pyrometallurgical tantalum wastewater and solid waste includes the following preparation steps: S1. The solid waste from pyrometallurgical tantalum was classified and pretreated separately to obtain different powdered products. S2. Add the different powdered products to the reaction containers respectively, add acid to each reaction container, pre-treat the tantalum-containing wastewater and pass it into each reaction container in proportion, perform salt filtration, and obtain different solutions and mixed membrane concentrates. S3. The different solutions are combined and then passed into a nanofiltration device for filtration; S4. The filtered solution is subjected to crystallization and evaporation separation to obtain high-purity component salts; S5. Add the reagent to the mixed membrane concentrate, stir, and then filter through a plate and frame filter press to obtain a filter cake; S6. Add acid to the filter cake, stir and leach, filter, adjust the pH of the filtrate to 8-9, generate a precipitate, and perform post-processing on the precipitate to obtain recovered tantalum. S7. Periodically pass the cleaning solution into the nanofiltration device for cleaning, collect the cleaning wastewater, and pass it into the reverse osmosis device for treatment to obtain recycled water.

[0020] Specifically, when pyrometallurgical tantalum solid waste is classified and pretreated separately, the pretreatment includes crushing and grinding.

[0021] Specifically, the solid waste from pyrometallurgical tantalum is first sorted manually or mechanically to distinguish between smelting slag and dust removal ash. The two types of solid waste are then fed into crushing equipment, such as a jaw crusher, to be crushed into block particles. The crushed block particles are then fed into grinding equipment to be ground into powder products for subsequent reactions.

[0022] It is understandable that the extraction efficiency of tantalum from solid waste depends on the contact area between the solid waste and the acid. Crushing and grinding can significantly increase the specific surface area, making it easier for the acid to penetrate into the solid waste and react fully with the tantalum compounds, thus facilitating the full leaching of the two chemically active tantalum compounds after separation.

[0023] Specifically, two powdered products and acids are added to two closed or open reaction vessels for dissolution reactions to obtain different salt solutions. Then, pretreated tantalum-containing wastewater is added to the two reaction vessels in a 1:1 ratio. At the same time, the stirring and heating devices of the reaction vessels are started to ensure that the powdered products and acids react fully. The salt solutions and tantalum-containing wastewater undergo a salt dissolution reaction and are then filtered to obtain different solutions and a mixed membrane concentrate.

[0024] Specifically, the reaction vessel can be a stirred reactor.

[0025] Understandably, the reaction vessel is equipped with a membrane integration module to achieve filtration and separation of different solutions and mixed membrane concentrates.

[0026] Specifically, pretreatment of tantalum-containing wastewater includes removing impurities such as colloidal silicon, suspended solids, and calcium and magnesium ions from the tantalum-containing wastewater.

[0027] It is understandable that the solution is a salt-containing solution and soluble tantalum compound formed after the powder product reacts with acid; the mixed membrane concentrate is a solution containing insoluble tantalum compound that is retained by the membrane during the salt filtration process.

[0028] Specifically, the solutions obtained from different reaction vessels are combined and pumped into a nanofiltration device. Under a certain operating pressure, the salts (monovalent ions) in the solutions permeate through the nanofiltration membrane, and the permeate is collected to obtain a salt-containing solution; tantalum compounds and Fe are retained by the membrane. 3+ Al 3+ Impurities are treated separately and can be recycled back to the reaction vessel in step 2.

[0029] Understandably, nanofiltration membranes possess a dual function of "charge selectivity" and "pore size sieving": tantalum compounds, such as TaCl5 and TaF7... 2- and Fe 3+ Al 3+ Multivalent ions are retained by the membrane due to their high charge density and particle size approaching the upper limit of the membrane pore size; while monovalent salt ions in wastewater, such as Na+, are retained by the membrane. + K + Cl - F - Due to its low charge density and small particle size, it can pass through the membrane into the solution, thereby achieving the separation of tantalum and impurities from salts.

[0030] Specifically, the process of obtaining high-purity component salts includes: First, the salt-containing solution is recrystallized to obtain the first type of salt and the mother liquor; The mother liquor was subjected to a first-stage evaporation treatment to obtain the initial second-type salt and the mother liquor; The mother liquor and daughter liquor were subjected to a two-stage evaporation process to obtain the third type of salt.

[0031] The initial type II salt was subjected to salt dissolution filtration to obtain a type II salt solution and an initial type III salt. The second type of salt is obtained by three-stage evaporation of the second type of salt solution; The initial third-type salt was subjected to a two-stage evaporation process to obtain the third-type salt.

[0032] Specifically, the first type of salt is potassium chloride, the second type of salt is sodium chloride, and the third type of salt is sodium fluoride.

[0033] It is understandable that by heating the salt solution to concentrate it to the saturation concentration of the first type of salt, and then cooling it, the first type of salt will precipitate in the form of crystals. During the crystallization process, most impurities will be rejected, thus obtaining a high-purity first type of salt; the salt that does not precipitate is retained in the mother liquor.

[0034] The solubility of the second type of salt in the mother liquor is between that of the first and third types of salts, and it is less affected by temperature. It is difficult to crystallize by cooling alone; evaporation is required to remove water and increase the concentration to saturation before precipitation. Since the third type of salt has not yet reached saturation, it remains in the mother and daughter liquors, achieving initial separation of the second and third types of salts. The initial second type of salt may contain a small amount of undissolved third type of salt particles or solid residues (such as membrane fragments or colloids). These can be redissolved with water (the third type of salt is insoluble at low concentrations due to its low solubility), followed by filtration to remove solid impurities and obtain a pure second type of salt solution. Having removed solid impurities through salt-dissolving filtration, the second type of salt solution can be further purified by evaporation, concentration, and crystallization to eliminate trace amounts of residual third type of salt (due to insufficient concentration), resulting in a higher purity of the precipitated second type of salt.

[0035] The third type of salt has the lowest solubility (or is minimally affected by temperature), requiring deep evaporation to concentrate the mother and daughter liquors to extremely high concentrations before precipitation. At this point, there are almost no other crystallizable salt components in the solution, so the third type of salt will precipitate alone, but may contain a small amount of fine impurities, forming the initial third type of salt. The initial third type of salt may contain trace amounts of second type of salt impurities. Through a two-stage process of "redissolving → evaporating and concentrating → crystallizing," these trace amounts of second type of salt can be retained in the mother liquor (because the concentration has not reached saturation), thus obtaining a high-purity third type of salt.

[0036] Specifically, the salt solution is passed into a crystallizer and heated to 60-80°C to concentrate the solution to the saturation concentration of the first type of salt; heating is stopped and the solution in the crystallizer is slowly cooled to 20-30°C to allow the first type of salt to fully crystallize and precipitate; the crystallization liquid is filtered, and the precipitated crystals are collected as the first type of salt, and the remaining solution after filtration is the mother liquor.

[0037] Specifically, the mother liquor is fed into a primary evaporator and heated and evaporated at atmospheric pressure and 80-90°C to remove 20%-30% of the water. When the second type of salt crystals appear in the solution, evaporation is stopped, and the liquid is sent to a filter. The crystals collected after filtration are the initial second type of salt, and the remaining solution is the mother liquor and daughter liquor.

[0038] Specifically, the mother liquor is fed into a two-stage evaporator and heated and evaporated at atmospheric pressure and 90-100°C to remove 40%-50% of the water until a crystallizing film appears on the surface of the solution. Evaporation continues for 5-10 minutes to allow the third type of salt to fully precipitate. The solution is then sent to a filter. The precipitated crystals are collected after filtration and are the initial third type of salt.

[0039] Specifically, the initial type II salt is added to a dissolving tank, along with an appropriate amount of room temperature deionized water, and stirred for 10-15 minutes to completely dissolve the type II salt. The dissolved solution is then passed through a precision filter with a pore size of 0.1-0.5 μm. The permeate obtained after filtration is the type II salt solution, and the retained solid is the undissolved initial type III salt, which is then combined with the initial type III salt.

[0040] Specifically, the second type of salt solution is passed into a three-stage evaporator and heated and evaporated at atmospheric pressure and 80-90℃ to concentrate it to a saturated concentration; then cooled to 30-40℃ to allow the second type of salt to crystallize out; after filtration, the crystals are collected, which is the high-purity second type of salt.

[0041] Specifically, the initial third-class salts after merging are added to a dissolving tank, a small amount of deionized water is added and heated to 60-70°C, and stirred to dissolve; the solution is passed into a two-stage evaporator and evaporated and concentrated until crystals precipitate; after filtration, the crystals are collected, which are high-purity third-class salts.

[0042] Understandably, by combining recrystallization-based preferential separation, multi-stage evaporation gradient concentration, and salt filtration for deep purification, the process addresses the differences in solubility of different salt components in a salt solution, enabling the stepwise separation and purification of multiple types of salts. Ultimately, it yields first, second, and third types of salts with acceptable purity, thus fundamentally solving the problem of mixed salt components and low purity caused by traditional single evaporation crystallization.

[0043] Specifically, a flocculant is added to the mixed membrane concentrate, and the mixture is stirred to cause the suspended solids to aggregate into flocs. The flocculated mixture is then fed into a plate and frame filter press, where pressure is applied for filtration. The retained solids are collected to obtain the filter cake. The filter cake is then added to a leaching container, acid is added, and the mixture is stirred and heated to dissolve the residual tantalum compounds in the filter cake. The mixture is then filtered to obtain a tantalum-containing filtrate. Ammonia is slowly added to the tantalum-containing filtrate to adjust the pH of the solution to 8-9, thereby generating tantalum hydroxide precipitate.

[0044] Specifically, tantalum hydroxide precipitate is collected by filtration and repeatedly washed with water to remove impurity ions attached to the surface; the washed tantalum hydroxide precipitate is then post-processed to obtain recovered tantalum in the form of tantalum oxide.

[0045] Specifically, the cleaning solution is periodically pumped into the nanofiltration unit for circulating cleaning. After cleaning, the cleaning wastewater is collected. The cleaning wastewater is then pumped into the reverse osmosis unit, where water molecules are forced to pass through the reverse osmosis membrane under high pressure. The permeate is collected to obtain recycled water. The concentrated liquid containing impurities retained by the membrane can be treated according to hazardous waste regulations or returned to the reaction vessel in S2.

[0046] As can be seen, this application improves the recovery rate of tantalum through solid waste classification and secondary leaching of filter cake; at the same time, it realizes the resource utilization of salt components through nanofiltration purification and evaporation crystallization, avoiding salt waste; it integrates salt dissolution and filtration, tantalum extraction and salt extraction into one, simplifying the dispersed steps in traditional processes, shortening the processing cycle, and reducing the equipment footprint; it obtains recycled water by treating cleaning wastewater through reverse osmosis, reducing fresh water consumption and wastewater discharge, and reducing environmental pressure; through nanofiltration impurity removal, precipitation purification, and washing and calcination multi-step purification, the purity of the recovered tantalum and high-purity component salts can meet the requirements for industrial reuse.

[0047] In some embodiments of this application, the solid waste from pyrometallurgical tantalum is crushed and ground before being passed through a 200-300 mesh sieve.

[0048] In some embodiments of this application, when adding acid to each reaction vessel, the added acid is either hydrochloric acid or hydrofluoric acid, and the solid-liquid ratio of the added acid to the powdered product is 1:5-1:10.

[0049] It is understandable that tantalum oxide (Ta₂O₅) can react with hydrochloric acid to form soluble TaCl₅, while tantalum carbonitride (TaCl₅) in dust collector ash... 0.5 N 0.5 The strong corrosiveness of hydrofluoric acid is required to break the carbon-nitrogen bond and form soluble TaF7. 2- Therefore, hydrochloric acid and hydrofluoric acid need to be added separately to match the different dissolution requirements of tantalum.

[0050] In some embodiments of this application, the pretreatment of tantalum-containing wastewater is ultrasonic treatment, with an ultrasonic frequency of 20-40 kHz and an ultrasonic time of 10-15 min.

[0051] Preferably, the ultrasonic frequency is 30kHz and the ultrasonic time is 12min.

[0052] In some embodiments of this application, before the reaction vessel is subjected to salt filtration, the temperature is adjusted to 50-90°C, the stirring rate is adjusted to 200-300 r / min, and the pH is adjusted to 2.5-3.5.

[0053] Preferably, the temperature is adjusted to 70°C, the stirring rate is adjusted to 250 r / min, and the pH is adjusted to 3.

[0054] In some embodiments of this application, the reagent is 0.1%-0.3% polyacrylamide.

[0055] In some embodiments of this application, after stirring, the filter cake is obtained by plate and frame filtration: The stirring time is 10-15 minutes, and the pressure of the plate and frame filter press is 0.8-1.2 MPa.

[0056] Preferably, the stirring time is 12 minutes and the pressure of the plate and frame filter press is 1 MPa.

[0057] In some embodiments of this application, acid is added to the filter cake, and during stirring, leaching, and filtration: The acid used is 1-2 mol / L hydrochloric acid, the leaching temperature is 60-70℃, and the leaching time is 1-1.5 h.

[0058] Preferably, the stirring leaching temperature is 65°C and the leaching time is 1.2 hours.

[0059] In some embodiments of this application, the post-processing specifically involves washing the precipitate with deionized water 3-5 times to adjust the pH to 7, and then calcining it at 800-1000°C for 2-3 hours to obtain recovered tantalum.

[0060] In some embodiments of this application, the cleaning solution is periodically passed into the nanofiltration device for cleaning, specifically as follows: Clean the nanofiltration device online for 30-40 minutes every 15-20 days with a mixed solution of 0.3-0.5 mol / L citric acid and 0.1-0.2 mol / L EDTA.

[0061] Specifically, the cleaning is carried out at room temperature.

[0062] Understandably, citric acid and EDTA work synergistically to simultaneously remove inorganic scale (such as tantalum hydroxide, calcium and magnesium salts) and metal ion adsorbent contaminants (such as Fe). 3+ Al 3+ The use of low-concentration acidic mixtures and mild cleaning conditions avoids chemical corrosion of nanofiltration membranes by high-concentration acids or strong oxidants, extending the service life of membrane modules and reducing membrane replacement costs. Online cleaning does not require disassembly of membrane modules, avoiding long-term production interruptions caused by offline cleaning.

[0063] Example 1 I. Raw material preparation: Pyrometallurgical tantalum solid waste includes: smelting slag (tantalum exists in the form of Ta2O5, tantalum content 2.1%), dust collector ash (tantalum exists in the form of TaC0.5N0.5, tantalum content 3.8%), and tantalum-containing wastewater (tantalum concentration 0.18 g / L, colloidal silicon 85 mg / L, fluoride ion concentration 4200 mg / L).

[0064] II. Specific steps: S1. The smelting slag and dust removal ash are sorted separately, crushed by a jaw crusher, and then ground in a ball mill. Both are passed through a 250-mesh sieve to obtain smelting slag powder and dust removal ash powder.

[0065] S2. Add smelting waste powder to reactor A and add 5 mol / L hydrochloric acid; add dust powder to reactor B and add 8 mol / L hydrofluoric acid. After treating the tantalum-containing wastewater with 30 kHz ultrasound for 12.5 min, introduce it into reactors A and B respectively at a 1:1 ratio; adjust the temperature of both reactors to 70℃, the stirring rate to 250 r / min, adjust the pH to 3.0 with dilute hydrochloric acid, and start the built-in ceramic microfiltration membrane module for salt dissolution filtration to obtain the dissolved solution from reactors A and B and the mixed membrane concentrate respectively.

[0066] S3. Combine the two solutions and pump them into the tantalum ion-imprinted nanofiltration membrane module for filtration at a pressure of 0.75 MPa.

[0067] S4. The nanofiltration permeate (containing a salt concentration of 3.5%) is fed into an evaporator crystallizer, heated to 75°C for concentration, and then cooled to 25°C for recrystallization to obtain the first type of salt (potassium chloride). The mother liquor is evaporated at 85°C for one stage to obtain the initial second type of salt (sodium chloride) and the mother liquor and daughter liquor. The mother liquor and daughter liquor are evaporated at 95°C for two stages to obtain the initial third type of salt (sodium fluoride). The initial second type of salt is dissolved in deionized water and filtered. The filtrate is evaporated at 85°C for three stages to obtain the second type of salt (sodium chloride). The initial third type of salt is combined, dissolved, and evaporated at 95°C for a second time to obtain the third type of salt (sodium fluoride).

[0068] S5. Add 0.2% polyacrylamide to the mixed membrane concentrate, stir for 12.5 min, and then send it to a plate and frame filter press for filtration under a pressure of 1.0 MPa to obtain filter cake.

[0069] S6. Add the filter cake to the leaching tank, add 1.5 mol / L hydrochloric acid, stir and leach at 65℃ for 1.25 h, filter to obtain tantalum-containing filtrate; add ammonia to the filtrate to adjust the pH to 8.5, generating tantalum hydroxide precipitate; wash the precipitate 4 times with deionized water until the pH is 7.0, and send it to a muffle furnace to calcine at 900℃ for 2.5 h to obtain recovered tantalum (tantalum dioxide).

[0070] S1. Every 17 days, use a mixed solution of 0.4 mol / L citric acid and 0.15 mol / L EDTA to clean the nanofiltration membrane module online for 35 min; collect the cleaning wastewater, pump it into the reverse osmosis membrane module, and clean it at 1.8 MPa pressure and room temperature to obtain recycled water.

[0071] Example 2 I. Raw material preparation: Pyrometallurgical tantalum solid waste: smelting slag (tantalum content 1.9%), dust removal ash (tantalum content 3.5%); tantalum-containing wastewater (tantalum concentration 0.15 g / L, colloidal silicon 70 mg / L, fluoride ion concentration 3800 mg / L).

[0072] II. Specific steps: S1. The smelting slag and dust removal ash are sorted separately, crushed by a jaw crusher, and then ground in a ball mill. Both are passed through a 200-mesh sieve to obtain smelting slag powder and dust removal ash powder.

[0073] S2. Add smelting waste powder to reactor A and add 5 mol / L hydrochloric acid; add dust powder to reactor B and add 8 mol / L hydrofluoric acid. After treating the tantalum-containing wastewater with 20 kHz ultrasound for 10 min, introduce it into reactors A and B respectively at a 1:1 ratio; adjust the temperature of both reactors to 80℃, the stirring rate to 200 r / min, adjust the pH to 2.5 with dilute hydrochloric acid, and start the built-in ceramic microfiltration membrane module for salt dissolution filtration to obtain the dissolved solution and mixed membrane concentrate from reactors A and B respectively.

[0074] S3. Combine the two solutions and pump them into the tantalum ion-imprinted nanofiltration membrane module for filtration at a pressure of 0.6 MPa.

[0075] S4. The nanofiltration permeate (containing a salt concentration of 3.5%) is fed into an evaporator crystallizer, heated to 70°C for concentration, and then cooled to 20°C for recrystallization to obtain the first type of salt (potassium chloride). The mother liquor is evaporated at 80°C for one stage to obtain the initial second type of salt (sodium chloride) and the mother liquor and daughter liquor. The mother liquor and daughter liquor are evaporated at 90°C for two stages to obtain the initial third type of salt (sodium fluoride). The initial second type of salt is dissolved in deionized water and filtered. The filtrate is evaporated at 80°C for three stages to obtain the second type of salt (sodium chloride). The initial third type of salt is combined, dissolved, and evaporated at 90°C for a second time to obtain the third type of salt (sodium fluoride).

[0076] S5. Add 0.1% polyacrylamide to the mixed membrane concentrate, stir for 10 minutes, and then send it to a plate and frame filter press for filtration under a pressure of 0.8 MPa to obtain filter cake.

[0077] S6. Add the filter cake to the leaching tank, add 1 mol / L hydrochloric acid, stir and leach at 60℃ for 1 h, filter to obtain tantalum-containing filtrate; add ammonia to the filtrate to adjust the pH to 8, and generate tantalum hydroxide precipitate; wash the precipitate with deionized water 3 times until the pH is 7.0, and send it to a muffle furnace to calcine at 800℃ for 2 h to obtain recovered tantalum (tantalum dioxide).

[0078] S1. Every 15 days, use a mixed solution of 0.3 mol / L citric acid and 0.1 mol / L EDTA to clean the nanofiltration membrane module online for 30 min; collect the cleaning wastewater, pump it into the reverse osmosis membrane module, and clean it at 1.5 MPa pressure and room temperature to obtain recycled water.

[0079] Example 3 I. Raw material preparation: Pyrometallurgical tantalum solid waste: smelting slag (tantalum content 2.3%), dust removal ash (tantalum content 4.2%); tantalum-containing wastewater (tantalum concentration 0.22 g / L, colloidal silicon 100 mg / L, fluoride ion concentration 4800 mg / L).

[0080] II. Specific steps: S1. The smelting slag and dust removal ash are sorted separately, crushed by a jaw crusher, and then ground in a ball mill. Both are passed through a 300-mesh sieve to obtain smelting slag powder and dust removal ash powder.

[0081] S2. Add smelting waste powder to reactor A and add 5 mol / L hydrochloric acid; add dust powder to reactor B and add 8 mol / L hydrofluoric acid. After treating the tantalum-containing wastewater with 40 kHz ultrasound for 15 min, introduce it into reactors A and B respectively at a 1:1 ratio; adjust the temperature of both reactors to 90℃, the stirring rate to 300 r / min, adjust the pH to 3.5 with dilute hydrochloric acid, and start the built-in ceramic microfiltration membrane module for salt dissolution filtration to obtain the dissolved solution and mixed membrane concentrate from reactors A and B respectively.

[0082] S3. Combine the two solutions and pump them into the tantalum ion-imprinted nanofiltration membrane module for filtration at a pressure of 0.9 MPa.

[0083] S4. The nanofiltration permeate (containing a salt concentration of 3.5%) is fed into an evaporator crystallizer, heated to 80°C for concentration, and then cooled to 30°C for recrystallization to obtain the first type of salt (potassium chloride). The mother liquor is evaporated at 90°C to obtain the initial second type of salt (sodium chloride) and the mother liquor and daughter liquor. The mother liquor and daughter liquor are evaporated at 100°C to obtain the initial third type of salt (sodium fluoride). The initial second type of salt is dissolved in deionized water and filtered. The filtrate is evaporated at 90°C to obtain the second type of salt (sodium chloride). The initial third type of salt is combined, dissolved, and evaporated at 100°C to obtain the third type of salt (sodium fluoride).

[0084] S5. Add 0.3% polyacrylamide to the mixed membrane concentrate, stir for 15 minutes, and then send it to a plate and frame filter press for filtration under a pressure of 1.2 MPa to obtain filter cake.

[0085] S6. Add the filter cake to the leaching tank, add 2 mol / L hydrochloric acid, stir and leach for 1.5 h at 70 °C, filter to obtain tantalum-containing filtrate; add ammonia to the filtrate to adjust the pH to 9, and generate tantalum hydroxide precipitate; wash the precipitate 5 times with deionized water until the pH is 7.0, and send it to a muffle furnace to calcine at 1000 °C for 3 h to obtain recovered tantalum (tantalum dioxide).

[0086] S1. Every 20 days, use a mixed solution of 0.5 mol / L citric acid and 0.2 mol / L EDTA to clean the nanofiltration membrane module online for 40 min; collect the cleaning wastewater, pump it into the reverse osmosis membrane module, and clean it at 2 MPa pressure and room temperature to obtain recycled water.

[0087] Effect test: The recovery rates of tantalum and salt in Examples 1-3 were tested, and the results were calculated as follows: Example 1 The total recovery rate of tantalum was 92.8%; The overall recovery rate of the three types of salts was 91.5%.

[0088] Example 2 The overall recovery rate of tantalum was 90.5%; The overall recovery rate of the three types of salts was 89.2%.

[0089] Example 3 The overall recovery rate of tantalum was 93.6%; The overall recovery rate of the three types of salts was 92.8%.

[0090] As can be seen, the tantalum recovery rate in Examples 1-3 is ≥90%; The total recovery rate of all three types of salts was ≥89%.

[0091] Understandably, the above data were all derived using calculation formulas in existing technologies.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration, characterized in that, The method comprises the following steps: The pyro-tantalum solid waste is classified and pretreated respectively to obtain different powder products; The different powder products are added into reaction containers respectively, acid is added into each reaction container, pretreated tantalum-containing wastewater is proportionally introduced into each reaction container, salt dissolution filtration is carried out, and different dissolution liquids and mixed membrane concentrate are obtained; The different dissolution liquids are combined and introduced into a nanofiltration device for filtration; The filtered dissolution liquid is subjected to crystallization and evaporation separation treatment to obtain high-purity component salt; An agent is added into the mixed membrane concentrate, and a filter cake is obtained after stirring and plate-and-frame pressure filtration; An acid is added into the filter cake, stirring leaching and filtration are carried out, the pH of the filtrate is adjusted to 8-9, a precipitate is generated, and the precipitate is subjected to post-treatment to obtain recovered tantalum; The nanofiltration device is cleaned regularly by introducing cleaning liquid into the nanofiltration device, cleaning wastewater is collected, and reused water is obtained by introducing the cleaning wastewater into a reverse osmosis device.

2. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 1, wherein the pyro-tantalum solid waste is crushed and ground, and then treated by passing through a 200-300 mesh sieve.

3. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 2, wherein when the acid is added into each reaction container, the acid added is one of hydrochloric acid or hydrofluoric acid, and the solid-liquid ratio of the acid added to the powder product is 1:5-1:

10.

4. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 3, wherein the pretreatment of the tantalum-containing wastewater is ultrasonic treatment, the ultrasonic frequency of the ultrasonic treatment is 20-40 kHz, and the ultrasonic time is 10-15 min.

5. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 4, wherein before the reaction container is subjected to salt dissolution filtration, the temperature is adjusted to 50-90℃, the stirring rate is adjusted to 200-300 r / min, and the pH is adjusted to 2.5-3.

5.

6. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 5, wherein the agent is 0.1%-0.3% polyacrylamide.

7. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 6, wherein when the stirring is followed by plate-and-frame pressure filtration to obtain a filter cake, the stirring time of the stirring is 10-15 min, and the pressure of the plate-and-frame pressure filtration is 0.8-1.2 MPa.

8. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 7, wherein when the acid is added into the filter cake, stirring leaching and filtration are carried out, the acid is 1-2 mol / L hydrochloric acid, the temperature of the stirring leaching is 60-70℃, and the leaching time is 1-1.5 h.

9. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 8, wherein the post-treatment is specifically ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The precipitate is washed with deionized water for 3-5 times, the PH is adjusted to 7, and the recovered tantalum is obtained by calcining at 800-1000 DEG C for 2-3 hours.

10. The method for recovering tantalum and salt from pyro-tantalum wastewater and solid waste by membrane integration according to claim 9, characterized in that, The periodic cleaning of the nanofiltration device with the cleaning solution is specifically: The nanofiltration device is cleaned with a mixed solution of 0.3-0.5 mol / L citric acid and 0.1-0.2 mol / L EDTA for 30-40 minutes every 15-20 days.

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