Method for extracting molybdenum and rhenium from molybdenum smelting washing flue gas wastewater step by step

Abstract

The invention relates to the technical field of three-waste treatment, in particular to a method for extracting molybdenum and rhenium from molybdenum smelting washing flue gas wastewater step by step, which is characterized by comprising the following specific operation steps: 1) pretreatment: carrying out impurity removal and oil removal treatment on the molybdenum smelting washing flue gas wastewater to obtain a purified solution; (2) adsorption and enrichment: enabling the purified liquid to pass through selective adsorption resin, so that molybdenum and rhenium are adsorbed and enriched on the resin together; (3) molybdenum is selectively analyzed, an ammonium sulfate solution serves as a first analysis agent, and a molybdenum-rich solution is obtained; and 4) deeply desorbing rhenium, and taking ammonia water as a second desorption agent to obtain a high-purity ammonium rhenate solution. The method has the beneficial effects that the average recovery rate of molybdenum reaches 95.1%, and the average recovery rate of rhenium reaches 98.5%. More importantly, the molybdenum impurity content in the obtained ammonium rhenate product is stably lower than 10 mg / L, and it is proved that the method can still achieve efficient and high-selectivity separation of molybdenum and rhenium on the industrial scale.

Description

Technical Field

[0001] This invention relates to the field of waste treatment technology, specifically to a method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting washing flue gas. Background Technology

[0002] During the smelting process, the flue gas, after being washed with water, produces acidic wastewater with a complex composition. This wastewater not only contains sulfuric acid but is also rich in valuable metals such as molybdenum and rhenium. It also often contains heavy metal impurities such as arsenic, copper, and lead, as well as oily organic matter. Rhenium is a scarce strategic metal with extremely high value, while molybdenum also has significant industrial value. Therefore, recovering molybdenum and rhenium from this wastewater has significant economic and environmental benefits.

[0003] Currently, ion exchange adsorption is a common technology for recovering molybdenum and rhenium from wastewater. However, the composition of this flue gas washing wastewater is complex, with many impurity ions, and direct adsorption can easily lead to resin poisoning. More challenging is the severe co-adsorption of molybdenum and rhenium on anion exchange resins. Traditional desorption methods (such as one-step desorption using strong alkali or high-concentration ammonia) typically elute molybdenum and rhenium simultaneously, resulting in a mixed molybdenum-rhenium solution. Subsequent complex chemical precipitation and solvent extraction processes are required to achieve separation, leading to problems such as long process flow, low metal recovery rate, easy cross-contamination of products, and high operating costs.

[0004] Application No. 201210212914.5 discloses a method for recovering rhenium and molybdenum from roasting flue ash of rhenium-molybdenum concentrate, belonging to the field of rare metal resource recovery. The method involves adding solvent and hydrogen peroxide to the roasting flue ash of rhenium-molybdenum concentrate, maintaining the temperature, and then filtering to obtain a filter cake and filtrate. The filter cake can be sent to a rotary kiln for oxidative roasting to prepare chemical molybdenum oxide. The pH of the filtrate is adjusted, and the supernatant obtained after settling is passed through an ion exchange resin column to obtain a molybdenum-containing eluent and a rhenium-containing eluent, which are further refined to achieve the recovery of rhenium and molybdenum from the roasting flue ash of rhenium-molybdenum concentrate. The method is simple in terms of equipment, process, and operation, not only reducing the molybdenum loss rate in the traditional molybdenum concentrate roasting flue ash treatment process, but also effectively recovering and utilizing the rare metal rhenium, creating economic benefits for enterprises. However, this process involves a mixture of solid and liquid phases, a long process flow, many control points, and high energy consumption during the heating process, which is not conducive to reducing production costs.

[0005] Therefore, developing a short-process technology that can directly separate and efficiently recover molybdenum and rhenium in situ from complex wastewater is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting flue gas. This method overcomes the shortcomings of existing technologies by employing a selective analytical extraction process to extract molybdenum and rhenium from the wastewater in molybdenum smelting flue gas in two steps. This allows for the recovery and utilization of economically valuable metallic molybdenum and rhenium. The entire process is heat-free and consumes no heat, thus meeting the requirements of shortening the process flow, improving separation efficiency, and ensuring the purity of the recovered products.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting water washing process, the specific operation steps of which are as follows: 1) Pretreatment: The wastewater from the washing flue gas of molybdenum smelting is treated to remove impurities and oil to obtain a purified liquid; 2) Adsorption and enrichment: The purified liquid obtained in step 1) is passed through a selective adsorption resin so that molybdenum and rhenium are both adsorbed and enriched on the resin. The time of action of the purified liquid on the selective adsorption resin is not less than 60 minutes. 3) Selective elution of molybdenum: An ammonium sulfate solution with a pH of 7.0-8.0 is used as the first elution agent to elute the resin saturated with adsorption in step 2), selectively eluting molybdenum, and collecting the effluent to obtain a molybdenum-rich solution; 4) Deeply analyze rhenium: Use 8%-15% ammonia water as the second analytical agent to analyze the resin after step 3), collect the analytical solution, and obtain a high-purity ammonium rhenium solution.

[0008] Furthermore, the composition and content of the molybdenum smelting water washing flue gas wastewater are: Mo 10-50 g / L, Re 0.2-1.0 g / L, total impurities of Cu, As, and Fe < 50 mg / L, and pH 1.0-2.5.

[0009] Furthermore, in step 1), the oil removal is accomplished using modified polyester fiber balls for filtration, and the modified polyester fiber balls have a specific surface area of ​​3000-8000 m². 2 / m 3 .

[0010] Furthermore, the selective adsorption resin used in step 2) is Zhengguang D302-Ⅱ.

[0011] Furthermore, the pH value of the ammonium sulfate solution in step 3) is 7.5.

[0012] Furthermore, in step 3), the concentration of the ammonium sulfate solution is 100-200 g / L.

[0013] Furthermore, the selective elution of molybdenum in step 3) is as follows: a) Preparation: Backwash the resin column after adsorption saturation in step 2) to remove surface suspended matter; b) Injection: Pump ammonium sulfate solution into the solution at a flow rate of 1-1.5 BV / h; c) Elution: Collect the effluent. Stop elution when the molybdenum concentration in the effluent drops to 10% of the influent concentration. d) Enrichment, at which point the effluent becomes a molybdenum-rich solution.

[0014] Furthermore, in step 4), the concentration of ammonia is 12.5%, and the flow rate of the analytical treatment in steps 3) and 4) is controlled at 1-3 BV / h.

[0015] Furthermore, the physicochemical parameters of the molybdenum-rich solution obtained in step 3) are a molybdenum content of 50-100 g / L.

[0016] Furthermore, the physicochemical parameters of the high-purity ammonium rhenium solution obtained in step 4) are: rhenium concentration of 50-150 g / L, and the contents of metal impurities Cu, Fe, Mo and W are all less than 5 ppm.

[0017] The principle of this invention is as follows: rhenium is eluted in the form of ammonium perrhenate, yielding a high-concentration ammonium perrhenate solution. This solution can be used directly as a product or further purified by evaporation and cooling crystallization to obtain ammonium perrhenate crystals. The resin adsorption and desorption reaction equations are as follows:

[0018] Perrhenate ions exist in solution as anions and are adsorbed onto the active groups of the resin. After the resin becomes saturated with adsorption, i.e., when the rhenium content in the effluent exceeds the limit or after adsorption saturation, the resin can be eluted. Ammonia is used as the eluent to elute the rhenium-loaded resin. The elution reaction equation is as follows:

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1) The invention achieves efficient and highly selective separation of molybdenum and rhenium. It creatively utilizes a weakly alkaline ammonium sulfate solution as a selective eluent and cleverly takes advantage of the fact that the resin’s adsorption capacity for molybdenum decreases sharply under this specific pH environment, while the adsorption of rhenium remains strong. This achieves the key step of eluting only molybdenum while completely retaining rhenium on the resin. This allows the separation of molybdenum and rhenium to be completed efficiently and cleanly during the eluent stage. 2) The process is concise and the product purity is high. Through a simple process of "one-step adsorption and two-step desorption", molybdenum-rich solution and high-purity ammonium rhenium solution are directly obtained, avoiding subsequent cumbersome separation steps, reducing metal loss, and improving product purity and direct recovery rate. The average recovery rate of molybdenum reaches 95.1%, and the average recovery rate of rhenium is as high as 98.5%. The molybdenum impurity content in the obtained ammonium rhenium product is consistently below 10 mg / L, which can achieve efficient and highly selective separation of molybdenum and rhenium. 3) Significant economic benefits: The method of this invention is simple to operate and has low reagent costs (ammonium sulfate and ammonia are both common and inexpensive chemicals). Furthermore, by protecting the resin from impurity contamination and optimizing the desorption process, the life of the resin is extended. The recovery process is carried out at room temperature without heating, which greatly reduces the recovery cost. 4) Combining resource utilization and environmental protection, the method of this invention transforms valuable metals in hazardous waste into high-value-added products, realizing the recycling of resources while reducing environmental pollution, which is in line with the development direction of green metallurgy. Attached Figure Description

[0020] Figure 1 This is a flowchart of a process embodiment of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The components of the embodiments of the present invention described and shown in the accompanying drawings can typically be arranged and designed in many different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0023] In the following examples, the composition and content of the treated molybdenum smelting washing flue gas wastewater are as follows: Mo 10-50 g / L, Re 0.2-1.0 g / L, total impurities of Cu, As, and Fe <50 mg / L, pH 1.0-2.5, and density approximately 1.12. The low molybdenum (Mo) concentration does not require high resin adsorption capacity, but sufficient contact time is necessary to achieve a high adsorption rate. A moderate rhenium (Re) concentration is beneficial for controlling the resin's penetration point and avoiding desorption difficulties caused by overload. Although the resin is not sensitive to interference from copper and arsenic, impurities (Cu, As, Fe) at high concentrations may still clog resin pores or cause competitive adsorption, requiring pretreatment for removal. Oil should be removed as much as possible before treatment, as an oil film can cover the resin surface, leading to a "false penetration" phenomenon, and must be thoroughly removed.

[0024] In this embodiment of the invention, the pretreatment process employs a PE pretreatment tank (with a stirrer), a quartz sand filter tank, a modified polyester fiber ball precision filter tank, and a plate and frame filter press. The adsorption-desorption system consists of two parallel stainless steel adsorption columns (specifications: Φ0.3m × H2.5m, resin filling capacity per column approximately 160L), along with a desorption liquid storage tank and a metering pump.

[0025] Example 1 A method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting water washing process, the specific operation steps of which are as follows: 1) Pretreatment: The wastewater from molybdenum smelting washing flue gas undergoes impurity and oil removal treatment. First, large particles are removed by quartz sand filtration, followed by deep oil removal and filtration using a modified polyester fiber ball precision filter. Then, iron salt is added to the clarified liquid to adjust the pH to neutral, and heavy metals such as arsenic and copper are removed by precipitation and filtration. Oil removal is completed using modified polyester fiber ball filtration, with a specific surface area of ​​5000 m². 2 / m 3 The purified solution is obtained. Wastewater is pumped into a pretreatment tank, where iron salt is added under stirring to adjust the pH to neutral, causing heavy metal ions such as arsenic and copper to precipitate as hydroxides. Subsequently, the solution is filtered sequentially through quartz sand filtration, fiber ball precision oil removal filtration, and finally through a plate and frame filter press for solid-liquid separation to obtain a clear purified solution.

[0026] 2) Adsorption and enrichment: The purified liquid obtained in step 1) is passed through a selective adsorption resin. The selective adsorption resin is a Zhengguang D302-Ⅱ type macroporous weakly basic anion exchange resin column, so that molybdenum and rhenium are adsorbed and enriched on the resin column (resin column volume 100mL). The reaction time of the purified liquid on the selective adsorption resin is 60min. 3) Selective elution of molybdenum: An ammonium sulfate solution with a pH of 7.5 and a concentration of 150 g / L was used as the first elution agent to elute the resin saturated in step 2). The elution flow rate was controlled at 2 BV / h. Molybdenum was selectively eluted. The steps for selective molybdenum elution are as follows: a) Preparation: Backwash the saturated resin column to remove surface suspended matter.

[0027] b) Injection: Pump an ammonium sulfate solution with pH=7.5 at a flow rate of 2 BV / h.

[0028] c) Elution: Collect the effluent. Stop elution when the molybdenum concentration in the effluent drops to 10% of the influent concentration.

[0029] d) Enrichment: The effluent at this point is a molybdenum-rich solution. The physicochemical parameters of the obtained molybdenum-rich solution are: molybdenum concentration higher than 15 g / L and rhenium content lower than 2 mg / L. The separation effect of molybdenum and rhenium is significant. 4) Deep rhenium analysis: A 12.5% ​​ammonia solution was used as the second eluent to analyze the resin after step 3). The flow rate was controlled at 2 BV / h, yielding a pale yellow, transparent ammonium rhenium solution. The eluent was collected to obtain a high-purity ammonium rhenium solution. The physicochemical parameters of the obtained high-purity ammonium rhenium solution were: Re concentration higher than 80 g / L, molybdenum content lower than 10 mg / L, indicating very high purity.

[0030] Example 2 A method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting water washing process, the specific operation steps of which are as follows: 1) Pretreatment: The wastewater from molybdenum smelting washing flue gas undergoes impurity and oil removal treatment. First, large particles are removed by quartz sand filtration, followed by deep oil removal and filtration using a modified polyester fiber ball precision filter. Then, iron salt is added to the clarified liquid to adjust the pH to neutral, and heavy metals such as arsenic and copper are removed by precipitation and filtration. Oil removal is completed using modified polyester fiber ball filtration, with a specific surface area of ​​8000 m². 2 / m 3 The purified solution was obtained; 2) Adsorption and enrichment: The purified solution obtained in step 1) is passed through a selective adsorption resin. The selective adsorption resin is a Zhengguang D302-Ⅱ type macroporous weakly basic anion exchange resin column, so that molybdenum and rhenium are adsorbed and enriched on the resin column (resin column volume 300mL). The reaction time of the purified solution on the selective adsorption resin is 60min. 3) Selective elution of molybdenum: An ammonium sulfate solution with a pH of 8.0 and a concentration of 100 g / L was used as the first elution agent to elute the resin saturated in step 2). The elution flow rate was controlled at 1 BV / h. Molybdenum was selectively eluted. The steps for selective molybdenum elution are as follows: a) Preparation: Backwash the saturated resin column to remove surface suspended matter.

[0031] b) Injection: Pump an ammonium sulfate solution with pH=7.5 at a flow rate of 2 BV / h.

[0032] c) Elution: Collect the effluent. Stop elution when the molybdenum concentration in the effluent drops to 10% of the influent concentration.

[0033] d) Enrichment: The effluent at this point is a molybdenum-rich solution. The physicochemical parameters of the obtained molybdenum-rich solution are: molybdenum concentration higher than 30 g / L and rhenium content lower than 5 mg / L. The separation effect of molybdenum and rhenium is significant. 4) Deep rhenium analysis: A 15% ammonia solution was used as the second eluent to analyze the resin after step 3). The flow rate was controlled at 1 BV / h, yielding a pale yellow, transparent ammonium rhenium solution. The eluent was collected to obtain a high-purity ammonium rhenium solution. The physicochemical parameters of the obtained high-purity ammonium rhenium solution were: Re concentration higher than 120 g / L, molybdenum content lower than 10 mg / L, indicating very high purity.

[0034] Example 3 A method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting water washing process, the specific operation steps of which are as follows: 1) Pretreatment: The wastewater from molybdenum smelting washing flue gas undergoes impurity and oil removal treatment. First, large particles are removed by quartz sand filtration, followed by deep oil removal and filtration using a modified polyester fiber ball precision filter. Then, iron salt is added to the clarified liquid to adjust the pH to neutral, and heavy metals such as arsenic and copper are removed by precipitation and filtration. Oil removal is completed using modified polyester fiber ball filtration, with a specific surface area of ​​6000 m². 2 / m 3 The purified solution was obtained; 2) Adsorption and enrichment: The purified liquid obtained in step 1) is passed through a selective adsorption resin. The selective adsorption resin is a Zhengguang D302-Ⅱ type macroporous weakly basic anion exchange resin column, so that molybdenum and rhenium are adsorbed and enriched on the resin column (resin column volume 100mL). The reaction time of the purified liquid on the selective adsorption resin is 60min. 3) Selective elution of molybdenum: An ammonium sulfate solution with a pH of 7.0 and a concentration of 200 g / L was used as the first elution agent to elute the resin saturated in step 2). The elution flow rate was controlled at 3 BV / h. Molybdenum was selectively eluted. The steps for selective molybdenum elution are as follows: a) Preparation: Backwash the saturated resin column to remove surface suspended matter.

[0035] b) Injection: Pump an ammonium sulfate solution with pH=7.5 at a flow rate of 3 BV / h.

[0036] c) Elution: Collect the effluent. Stop elution when the molybdenum concentration in the effluent drops to 10% of the influent concentration.

[0037] d) Enrichment: The effluent is then a molybdenum-rich solution. The effluent is collected to obtain a molybdenum-rich solution. The physicochemical parameters of the obtained molybdenum-rich solution are: molybdenum concentration higher than 10 g / L and rhenium content lower than 2 mg / L. The separation effect of molybdenum and rhenium is significant. 4) Deep rhenium analysis: A 12.5% ​​ammonia solution was used as the second eluent to analyze the resin after step 3). The flow rate was controlled at 3 BV / h, yielding a pale yellow, transparent ammonium rhenium solution. The eluent was collected to obtain a high-purity ammonium rhenium solution. The physicochemical parameters of the obtained high-purity ammonium rhenium solution were: Re concentration higher than 50 g / L, molybdenum content lower than 10 mg / L, indicating very high purity.

[0038] The key data records of the experiments in Examples 1-3 of this invention are shown in Table 1.

[0039] Table 1. Key data records for experiments in Examples 1-3: .

[0040] Comparative Example Saturated resin from the same batch was directly eluted using 12.5% ​​ammonia at a flow rate of 1 BV / h. The collected eluent was a mixed solution of molybdenum and rhenium, with a Mo concentration of approximately 12 g / L and a Re concentration of approximately 7 g / L. Subsequent solvent extraction or precipitation steps were required to separate the two compounds, resulting in a lengthy process and low recovery rate.

[0041] The comparison between the examples and the comparative examples clearly shows that the stepwise analysis method provided by the present invention has an overwhelming advantage in separation efficiency and product purity, successfully solves the technical bottleneck of molybdenum-rhenium separation, and has verified its stability, reliability and economy under large-scale production conditions.

[0042] The embodiments of this invention exhibit better process stability. When scaled up to process one ton of waste acid, the process operates smoothly with seamless transitions between steps. Key process parameters (such as the pH, concentration, and flow rate of the eluent) are easily controlled, demonstrating good reproducibility. The average recovery rate of molybdenum reaches 95.1%, and the average recovery rate of rhenium is as high as 98.5%. Most importantly, the molybdenum impurity content in the resulting ammonium rheniumate product is consistently below 10 mg / L, proving that the method of this invention can still achieve efficient and highly selective separation of molybdenum and rhenium on an industrial scale. This method can convert complex smelting waste acid into high-purity ammonium rheniumate solution and molybdenum-rich solution, turning waste into treasure, possessing significant environmental and economic benefits, and providing solid data support and practical evidence for large-scale industrial application.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for stepwise extraction of molybdenum and rhenium from wastewater from molybdenum smelting water washing process, characterized in that, The specific steps are as follows: 1) Pretreatment: The wastewater from the washing flue gas of molybdenum smelting is treated to remove impurities and oil to obtain a purified liquid; 2) Adsorption and enrichment: The purified liquid obtained in step 1) is passed through a selective adsorption resin so that molybdenum and rhenium are both adsorbed and enriched on the resin. The time of action of the purified liquid on the selective adsorption resin is not less than 60 minutes. 3) Selective elution of molybdenum: An ammonium sulfate solution with a pH of 7.0-8.0 is used as the first elution agent to elute the resin saturated with adsorption in step 2), selectively eluting molybdenum, and collecting the effluent to obtain a molybdenum-rich solution; 4) Deeply analyze rhenium: Use 8%-15% ammonia water as the second analytical agent to analyze the resin after step 3), collect the analytical solution, and obtain a high-purity ammonium rhenium solution.

2. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... The composition and content of the wastewater from the molybdenum smelting water washing process are: Mo 10-50 g / L, Re 0.2-1.0 g / L, total impurities of Cu, As, and Fe <50 mg / L, and pH 1.0-2.

5.

3. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... In step 1), the oil removal is accomplished using modified polyester fiber balls for filtration. The modified polyester fiber balls have a specific surface area of ​​3000-8000 m². 2 / m 3 .

4. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... The selective adsorption resin used in step 2) is Zhengguang D302-Ⅱ.

5. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... The pH value of the ammonium sulfate solution in step 3) is 7.

5.

6. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... The concentration of the ammonium sulfate solution in step 3) is 100-200 g / L.

7. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... The selective molybdenum elution procedure in step 3) is as follows: a) Preparation: Backwash the resin column after adsorption saturation in step 2) to remove surface suspended matter; b) Injection: Pump ammonium sulfate solution into the solution at a flow rate of 1-1.5 BV / h; c) Elution: Collect the effluent. Stop elution when the molybdenum concentration in the effluent drops to 10% of the influent concentration. d) Enrichment, at which point the effluent becomes a molybdenum-rich solution.

8. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting water washing, as described in claim 1, is characterized in that... In step 4), the concentration of ammonia is 12.5%, and the flow rate of the analytical treatment in steps 3) and 4) is controlled at 1-3 BV / h.

9. The method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting washings according to claim 1, characterized in that, The physicochemical parameters of the molybdenum-rich solution obtained in step 3) are a molybdenum content of 50-100 g / L.

10. A method for stepwise extraction of molybdenum and rhenium from wastewater in molybdenum smelting washings according to claim 1, characterized in that, The physicochemical parameters of the high-purity ammonium rhenium solution obtained in step 4) are: rhenium concentration 50-150 g / L, and the contents of metal impurities Cu, Fe, Mo and W are all less than 5 ppm.

Images