Method for the combined recovery of lead metal from a contaminated solution by biomineralization-flotation

Abstract

The application discloses a method for recovering lead metal in a contaminated solution by combining bio-mineralization and flotation, which comprises the following steps: 1, bacterial activation; 2, bacterial expansion; 3, adding urea and bacterial cementing solution into the contaminated solution, and performing mineralization by shaking bed oscillation to obtain a mineral slurry; 4, adding a foaming agent into the mineral slurry and stirring; 5, adding a collecting agent into the uniformly foamed mineral slurry, and then transferring the slurry into a flotation column with a leaching and defoaming device to perform flotation; and 6, centrifuging and drying the recovery product in a collecting tank to realize recovery of the lead metal.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering technology, specifically relating to a method for the combined recovery of lead metal from polluted solutions using biomineralization-flotation. Background Technology

[0002] With the further development of industrialization and technological advancement, environmental pollution has gradually become a major focus of social concern. Among these issues, heavy metal pollution of soil and water caused by human activities such as unreasonable industrial emissions, agricultural input application, and atmospheric deposition is particularly serious. Because heavy metals cannot be decomposed by microorganisms in soil and water, they accumulate and transform into toxic methyl compounds. Furthermore, due to the presence of groundwater and rainfall, heavy metals in soil and water are highly mobile, posing even greater harm to the environment and organisms.

[0003] Currently, existing methods for treating heavy metal pollution in water bodies are mainly divided into three categories: physical methods, chemical methods, and biological methods. Most of these methods focus on converting free heavy metal ions into precipitates or other less soluble forms, making them less prone to migration and thus limiting the degree of pollution. However, most existing technologies rely on adding chemical reagents such as precipitants, oxidants, and reducing agents to achieve the conversion of heavy metal forms. These added chemical reagents can easily cause secondary pollution, thus current methods for treating heavy metal pollution in water bodies still have certain limitations. Bioremediation technology, on the other hand, is an emerging technology that utilizes the absorption and conversion of heavy metals by microorganisms or plants to remove them. Microbial induced carbonate precipitation (MICP) technology, in particular, utilizes CO3 produced by the hydrolysis of urea by urease-producing bacteria. 2- Lead ions combine with free heavy metal ions, transforming them into carbonate precipitates, thus limiting their migration and reducing their pollution levels. Based on the advantages of biological methods for remediating heavy metal-contaminated water bodies—high efficiency, environmental friendliness, and no secondary pollution—they have gradually become a hot topic in the field of environmental geotechnical engineering in recent years. Traditional MICP technology converts free lead metal into lead carbonate precipitates by adding expanded Bacillus pasteurization culture and urea to the contaminated solution, reducing its biotoxicity by limiting its flowability. However, the solidified lead metal still poses a risk of secondary release over time; traditional flotation techniques for treating heavy metal-contaminated solutions typically involve chemical precipitation of heavy metal ions followed by recovery, and the chemical reagents used may also cause secondary pollution to the environment.

[0004] Flotation, also known as flotation mineral processing, is a technique that separates minerals based on differences in their surface hydrophobicity. By adding flotation reagents such as frothers and collectors, the target mineral adheres to the bubbles generated by the frother in the slurry and is carried out of the flotation cell by aeration, thus achieving the recovery of the target mineral. This technology is currently widely used in industrial processes for separating metallic minerals, non-metallic minerals, and chemical raw materials. However, research on its application in the treatment of heavy metal pollution is limited. Furthermore, for heavy metal pollution in water bodies, the current method primarily involves adding chemical reagents to convert heavy metal ions into precipitates before recovery, which still carries a high risk of secondary pollution. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for the combined biomineralization-flotation recovery of lead metal from contaminated solutions. This method involves adding a bacterial solution of Bacillus pasteurellii and urea to the contaminated solution to induce a mineralization reaction, converting lead ions in the solution into carbonate precipitates. The resulting mixture of the mineralized solution and the precipitate is then transferred to a flotation column. Aeration is achieved using an air pump, combined with the assistance of flotation reagents, ultimately recovering the lead from the solution.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for recovering lead metal from a polluted solution by a combination of biomineralization and flotation, characterized by comprising the following steps:

[0007] Step 1: Bacterial activation: Place the lyophilized powder of Bacillus pasteurellii in a liquid culture medium, and culture it under constant temperature and shaking to obtain activated bacteria, which are then stored.

[0008] Step 2, bacterial expansion: Mix the bacterial solution preserved in Step 1 with liquid culture medium, and culture in a shaker at a constant temperature to obtain a bacterial gel solution;

[0009] Step 3, Induced mineralization: Urea and the bacterial cementing solution described in Step 2 are added to the contaminated solution, and the solution is shaken on a shaker to mineralize, resulting in a slurry;

[0010] Step 4: Uniform foaming: Add the foaming agent to the slurry described in Step 3 and stir;

[0011] Step 5, aerated flotation: Add the collector to the slurry that has been stirred and foamed uniformly in Step 4, and then transfer it to a flotation column equipped with a washing and defoaming device. Use an air pump to aerate the flotation column for flotation, and turn on the washing and defoaming device to pump distilled water into the flotation column.

[0012] Step Six: Product Recovery: The recovered product in the collection tank is centrifuged and dried to recover lead metal; the recovered product is acidified with dilute nitric acid, and the Pb content in the acidified solution is measured. 2+The concentration is used to evaluate flotation performance.

[0013] The above-mentioned method for recovering lead metal from polluted solutions by combined biomineralization and flotation is characterized in that the isothermal oscillation culture in steps one and three is at a temperature of 26-30°C, an oscillation rate of 140-160 rpm, and a culture time of 24-26 h.

[0014] The above-mentioned method for recovering lead metal from polluted solutions by combined biomineralization and flotation is characterized in that the liquid culture medium in steps one and three contains yeast extract at a concentration of 14–26 g / L, urea at a concentration of 18–24 g / L, ammonium chloride at a concentration of 8–14 g / L, manganese sulfate monohydrate at a concentration of 6–14 mg / L, nickel chloride hexahydrate at a concentration of 24–30 mg / L, and a pH value of 8–9.

[0015] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization and flotation is characterized in that the volume ratio of bacterial solution to liquid culture medium in step two is 1:(100-1000), and the OD600 of the bacterial cement solution is 1.5-2.0.

[0016] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization and flotation is characterized in that, in step three, the lead concentration in the contaminated solution is 10-30 mmol / L, 5-15 mmol of urea is added to 100 mL of the contaminated solution, 5-10 mL of bacterial cementing solution is added to 100 mL of the contaminated solution, and the temperature of the shaking mineralization is 26-30℃, and the shaking rate is 140-160 rpm.

[0017] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization and flotation is characterized in that the frother in step four is dodecyltrimethylammonium bromide, and its concentration in the slurry is 0.1-0.5 mmol / L.

[0018] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization and flotation is characterized in that the flotation column with a rinsing and defoaming device mentioned in step five refers to a flotation column with a rinsing port at the edge of the collection tank, and a water pipe installed on the rinsing port. The water pipe is connected to a pump to pump distilled water into the flotation column.

[0019] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization and flotation is characterized in that the collector in step five is dodecylamine, and the concentration of the collector in the pulp is 0.1-0.5 mmol / L.

[0020] The above-mentioned method for recovering lead metal from polluted solutions by combined biomineralization and flotation is characterized in that the aeration rate of the aeration flotation in step five is 2 to 6 L / min.

[0021] The above-mentioned method for the combined biomineralization-flotation recovery of lead metal from polluted solutions is characterized in that, in step six, the flotation efficiency at the start of flotation (5 min, 10 min, and 20 min) is used as an indicator to evaluate the flotation performance.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The method of this invention combines microbial-induced carbonate precipitation technology with flotation technology to recover lead metal from contaminated solutions. It replaces the chemical precipitation method used in traditional flotation processes with biologically induced precipitation, reducing the risk of secondary pollution that may result from adding chemical reagents, while overcoming the problem of low economic efficiency caused by adding large amounts of chemical precipitants. Subsequently, the mineralized products generated after the lead ions in the contaminated solution are solidified are floated to achieve the recovery of lead metal from the contaminated solution, resulting in significant economic benefits.

[0024] 2. This invention adds a rinsing and defoaming device to the traditional flotation column, which can quickly defoam the foam adsorbed with the target mineral in the recovery tank after flotation. Compared with the traditional flotation column which uses a scraper to remove the foam, the addition of the rinsing and defoaming device can effectively prevent the foam from overflowing from the flotation tank, which facilitates recovery and reduces the risk of resource waste.

[0025] 4. The preferred frother in this invention is dodecyltrimethylammonium bromide, and the collector is dodecylamine, both of which are cationic surfactants. The structure of a surfactant can be divided into a hydrophilic end and a hydrophobic end. Therefore, to a certain extent, both the frother and the collector have both frother and collector functions, and the flotation efficiency can reach up to 84.5%.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the flotation column with a rinsing and defoaming device according to the present invention.

[0028] Figure 2 This is a schematic diagram of the flotation efficiency in Embodiment 1 of the present invention.

[0029] Figure 3 This is a schematic diagram of the flotation efficiency of Comparative Example 1.

[0030] Figure 4 This is a schematic diagram of the flotation efficiency of Comparative Example 2.

[0031] Figure 5 This is a schematic diagram of the flotation efficiency of Comparative Example 3.

[0032] Figure 6This is a molecular dynamics simulation result of the adsorption of flotation reagents on the surface of mineralized products under the combination of cationic frother and cationic collector in Example 1 of the present invention.

[0033] Figure 7 The results are based on molecular dynamics simulations of the adsorption of flotation reagents on the surface of mineralized products under the combination of cationic frother and anionic collector in Comparative Example 1.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1—Flotation column; 2—Collection tank; 3—Washing port; 4—Water pipe;

[0036] 5—Pump; 6—Distilled water. Detailed Implementation

[0037] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention are described in detail below with reference to examples. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0038] The following description, in conjunction with specific embodiments, illustrates the content of the present invention. However, the following description is not intended to limit the scope of the present invention.

[0039] The flotation column with rinsing and defoaming device described in the following embodiments refers to a flotation column 1 with a rinsing port 3 at the edge of the collection tank 2, and a water pipe 4 installed on the rinsing port 3. The water pipe 4 is connected to a pump 5 to pump distilled water 6 into the flotation column. For the specific structure, see [link to specific description]. Figure 1 .

[0040] Example 1

[0041] The method for recovering lead metal from a contaminated solution using a combined biomineralization-flotation process, as described in this embodiment, includes the following steps:

[0042] Step 1, bacterial activation, specifically includes: placing 1.0 mg of lyophilized Pasteurella multocida powder into a 250 mL Erlenmeyer flask containing 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing it for 26 h in a constant temperature shaking incubator set at 30℃ and a shaking rate of 140 rpm to obtain activated bacteria. The activated bacteria are then mixed with glycerol at a volume ratio of 7:3 and frozen at -20℃. The bacteria are Pasteurella multocida, purchased from the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC 1.3687.

[0043] The liquid culture medium contains 20 g / L yeast extract, 20 g / L urea, 10 g / L ammonium chloride, 10 mg / L manganese chloride monohydrate, 26 mg / L nickel chloride hexahydrate, pH 8.8, and is sterilized at 0.105 MPa and 121°C for 30 min under high temperature and high pressure.

[0044] Step 2, bacterial expansion culture, specifically includes: adding the bacterial solution preserved in Step 1 to the liquid culture medium, and culturing it in a constant temperature incubator with a shaking rate of 140 rpm and a temperature of 30°C for 26 h to obtain a bacterial gel solution with an OD600 of 1.5; the volume ratio of the bacterial solution to the liquid culture medium is 1:1000; the liquid culture medium is the same as the liquid culture medium in Step 1.

[0045] Step 3, inducing mineralization, specifically includes: adding 10 mmol of urea and 7 mL of the bacterial cementing solution described in Step 3 to a solution containing 30 mmol of Pb. 2+ Mineralization was carried out in 100 mL of deionized water at 30 °C and a shaking rate of 140 rpm for 24 h on a shaking table to obtain a slurry containing lead carbonate precipitate.

[0046] Step 4, uniform foaming, specifically includes: adding 0.5 mL of a 0.1 mol / L cationic foaming agent solution to the slurry described in Step 3, and then stirring on a magnetic stirrer for 5 min; the cationic foaming agent used is dodecyltrimethylammonium bromide;

[0047] Step 5, aerated flotation, specifically includes: adding 0.5 mL of a 0.1 mol / L cationic collector solution to the uniformly foamed slurry stirred in Step 4, then transferring it to a flotation column equipped with a rinsing and defoaming device; starting the air pump for aerated flotation; and activating the rinsing and defoaming device to pump distilled water into the flotation column to rapidly defoam the foam adsorbed with the target mineral in the recovery tank, effectively preventing foam from overflowing from the flotation tank; the cationic collector used is dodecylamine; the aeration rate for aerated flotation is 4 L / min;

[0048] Step Six: Product Recovery. This includes: returning the recovered product from the flotation column's collection tank to a beaker through a drain port; centrifuging the solid-liquid mixture in the beaker; drying the resulting solid to ultimately recover lead metal from the solution; using the flotation efficiency at 5, 10, and 20 minutes after the start of flotation as indicators of performance; and acidifying the recovered product with dilute nitric acid. Specifically, under stirring conditions, 10% dilute nitric acid is added dropwise to the recovered product until the solution becomes clear, and the Pb concentration in the acidified solution is measured. 2+ The concentration is used to evaluate flotation performance.

[0049] Comparative Example 1

[0050] This comparative example is the same as Example 1, except that the foaming agent is anionic sodium dodecyl sulfate and the collector is anionic sodium dodecyl sulfate reagent.

[0051] Comparative Example 2

[0052] This comparative example is the same as Example 1, except that the collector is an anionic collector, sodium dodecyl sulfate reagent.

[0053] Comparative Example 3

[0054] This comparative example is the same as Example 1, except that the foaming agent is an anionic foaming agent, sodium dodecyl sulfonate.

[0055] Example 2

[0056] The method for recovering lead metal from a contaminated solution using a combined biomineralization-flotation process, as described in this embodiment, includes the following steps:

[0057] Step 1, bacterial activation, specifically includes: placing 1.0 mg of lyophilized Pasteurella multocida powder into a 250 mL Erlenmeyer flask containing 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing it for 24 h in a constant temperature shaking incubator set at 26℃ and a shaking rate of 160 rpm to obtain activated bacteria. The activated bacteria are then mixed with glycerol at a volume ratio of 7:3 and frozen at -20℃. The bacteria are Pasteurella multocida, purchased from the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC 1.3687.

[0058] The liquid culture medium contains 14 g / L yeast extract, 18 g / L urea, 8 g / L ammonium chloride, 6 mg / L manganese chloride monohydrate, 24 mg / L nickel chloride hexahydrate, pH 8, and is sterilized at 0.105 MPa and 121°C for 30 min under high temperature and high pressure.

[0059] Step 2, bacterial expansion culture, specifically includes: adding the bacterial solution preserved in Step 1 to the liquid culture medium, and culturing it in a constant temperature incubator with a shaking rate of 160 rpm and a temperature of 26℃ for 24 hours to obtain a bacterial gel solution with an OD600 of 1.8; the volume ratio of the bacterial solution to the liquid culture medium is 1:500; the liquid culture medium is the same as the liquid culture medium in Step 1.

[0060] Step 3, inducing mineralization, specifically includes: adding 5 mmol of urea and 5 mL of the bacterial cementing solution described in Step 3 to a solution containing 10 mmol of Pb. 2+In 100 mL of deionized water, the mineral was mineralized by shaking on a shaker at a temperature of 26 °C and a shaking rate of 140 rpm for 24 h to obtain a slurry containing lead carbonate precipitate.

[0061] Step 4, uniform foaming, specifically includes: adding 0.3 mL of a 0.1 mol / L cationic foaming agent solution to the slurry described in Step 3, and then stirring on a magnetic stirrer for 5 min; the cationic foaming agent used is dodecyltrimethylammonium bromide;

[0062] Step 5, aerated flotation, specifically includes: adding 0.3 mL of a 0.1 mol / L cationic collector solution to the uniformly foamed slurry stirred in Step 4, then transferring it to a flotation column equipped with a rinsing and defoaming device; starting the air pump for aerated flotation; and activating the rinsing and defoaming device to pump distilled water into the flotation column to rapidly defoam the foam adsorbed with the target mineral in the recovery tank, effectively preventing foam from overflowing from the flotation tank; the cationic collector used is dodecylamine; the aeration rate for aerated flotation is 2 L / min;

[0063] Step six, product recovery, specifically includes: returning the recovered product from the collection tank of the flotation column to the beaker through the inlet, then centrifuging the solid-liquid mixture in the beaker, drying the solid obtained by centrifugation, and finally recovering the lead metal from the solution.

[0064] Example 3

[0065] The method for recovering lead metal from a contaminated solution using a combined biomineralization-flotation process, as described in this embodiment, includes the following steps:

[0066] Step 1, bacterial activation, specifically includes: placing 1.0 mg of lyophilized Pasteurella multocida powder into a 250 mL Erlenmeyer flask containing 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing it for 25 h in a constant temperature shaking incubator set at 28℃ and a shaking rate of 150 rpm to obtain activated bacteria. The activated bacteria are then mixed with glycerol at a volume ratio of 7:3 and frozen at -20℃. The bacteria are Pasteurella multocida, purchased from the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC 1.3687.

[0067] The liquid culture medium contains 26 g / L yeast extract, 24 g / L urea, 14 g / L ammonium chloride, 14 mg / L manganese chloride monohydrate, 30 mg / L nickel chloride hexahydrate, pH 9, and is sterilized at 0.105 MPa and 121°C for 30 min under high temperature and high pressure.

[0068] Step 2, bacterial expansion culture, specifically includes: adding the bacterial solution preserved in Step 1 to the liquid culture medium, and culturing it in a constant temperature incubator with a shaking rate of 150 rpm and a temperature of 28°C for 25 h to obtain a bacterial gel solution with an OD600 of 2; the volume ratio of the bacterial solution to the liquid culture medium is 1:100; the liquid culture medium is the same as the liquid culture medium in Step 1.

[0069] Step 3, inducing mineralization, specifically includes: adding 15 mmol of urea and 10 mL of the bacterial cementing solution described in Step 3 to a solution containing 20 mmol of Pb. 2+ In 100 mL of deionized water, the mineral was mineralized by shaking on a shaker at a temperature of 28 °C and a shaking rate of 150 rpm for 24 h to obtain a slurry containing lead carbonate precipitate.

[0070] Step 4, uniform foaming, specifically includes: adding 0.1 mL of a 0.1 mol / L cationic foaming agent solution to the slurry described in Step 3, and then stirring on a magnetic stirrer for 5 min; the cationic foaming agent used is dodecyltrimethylammonium bromide;

[0071] Step 5, aerated flotation, specifically includes: adding 0.1 mL of a 0.1 mol / L cationic collector solution to the uniformly foamed slurry stirred in Step 4, then transferring it to a flotation column equipped with a rinsing and defoaming device; starting the air pump for aerated flotation; and activating the rinsing and defoaming device to pump distilled water into the flotation column to rapidly defoam the foam adsorbed with the target mineral in the recovery tank, effectively preventing foam from overflowing from the flotation tank; the cationic collector used is dodecylamine; the aeration rate for aerated flotation is 6 L / min;

[0072] Step six, product recovery, specifically includes: returning the recovered product from the collection tank of the flotation column to the beaker through the inlet, then centrifuging the solid-liquid mixture in the beaker, drying the solid obtained by centrifugation, and finally recovering the lead metal from the solution.

[0073] Performance Evaluation

[0074] The flotation performance of Example 1 and Comparative Examples 1-3 was evaluated, and the results are shown in the figure. Figure 2-5Frothing agents and collectors, as flotation reagents, play different roles in flotation. Based on the different charges of their polar groups, frothers and collectors can be classified as anionic and cationic. Frothing agents generate more fine bubbles in the pulp by reducing the gas-liquid interfacial tension and increasing the dispersion of air in the pulp. Subsequently, collectors selectively adsorb onto the surface of the minerals to be floated, forming a hydrophobic layer. This allows the hydrophobic mineral particles to adhere to the bubbles and float to the froth product, thus achieving mineral flotation. Only by combining both and using them in a complementary manner can a more ideal flotation effect be achieved. Figures 2-5 The results show the flotation efficiency of lead in contaminated solutions using combinations of cationic frother × cationic collector (cation × cation), anionic frother × anionic collector (anionic × anionic), cationic frother × anionic collector (cation × anionic), and anionic frother × cationic collector (anionic × cation). Figure 2 It is evident that Embodiment 1 of the present invention achieves a superior flotation efficiency (up to 84.5%), far exceeding the effects of the other three combinations. This phenomenon is primarily due to the fact that the flotation reagents in Embodiment 1 carry the same valence charge, resulting in electrostatic repulsion between the reagents and thus a dispersed state. Furthermore, the negatively charged lead carbonate, due to electrostatic attraction, readily adsorbs onto the positively charged flotation reagents. The combined effect of these two factors leads to the superior flotation effect achieved in this combination. Figure 6 As shown.

[0075] according to Figure 3 It is evident that with the anion-to-anion combination, the final flotation effect deteriorates with increasing flotation time, achieving only a flotation efficiency of 19.9%. This phenomenon is primarily due to the fact that lead carbonate's zero charge point (Zeta potential of 0) corresponds to a pH of 4.8. In the MIP technology, the hydrolysis of urea releases OH- ions, leading to an alkaline pulp. Therefore, lead carbonate has a negative surface charge in the pulp. Due to electrostatic effects, it strongly repels the negatively charged anionic flotation reagents, resulting in poor flotation performance. Furthermore, for... Figure 4 and Figure 5 It is evident that even with cationic x anionic and anionic x cationic combinations, the final flotation efficiency remains poor, at only 18.5% and 20.4%, respectively. This phenomenon may be due to the fact that, in these two combinations, the electrostatic force between the dissimilarly charged flotation reagents is greater than the interaction between the reagents and the mineral surface. This causes the reagents to preferentially bind together to form micelles, preventing them from effectively adhering to the mineral surface and exerting their effect. The results obtained from modeling mineral crystal faces and flotation reagent molecules based on molecular dynamics, and simulating their adsorption in the actual pulp solution environment, are as follows... Figure 7As shown, it can be observed that the flotation reagents combine with each other to form micelles, which prevents them from playing their respective roles properly, thus resulting in poor flotation performance.

[0076] This invention combines microbial-induced carbonate precipitation technology with flotation technology to recover lead metal from contaminated solutions. By replacing the traditional chemical precipitation method with bio-induced precipitation, it reduces the risk of secondary pollution from the addition of chemical reagents and overcomes the problem of low economic efficiency resulting from the addition of large amounts of chemical precipitants. Subsequently, the mineralized products formed after the lead ions in the contaminated solution are solidified are floated to achieve the recovery of lead metal from the contaminated solution, resulting in significant economic benefits.

[0077] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the invention shall still fall within the protection scope of the present invention.

Claims

1. A method for recovering lead metal from a contaminated solution using a combined biomineralization-flotation process, characterized in that, Includes the following steps: Step 1: Bacterial activation: Place the lyophilized powder of Bacillus pasteurellii in a liquid culture medium, and culture it under constant temperature and shaking to obtain activated bacteria, which are then stored. Step 2, bacterial expansion: Mix the bacterial solution preserved in Step 1 with liquid culture medium, and culture in a shaker at a constant temperature to obtain a bacterial gel solution; Step 3, Induced mineralization: Urea and the bacterial cementing solution described in Step 2 are added to the contaminated solution, and the solution is shaken on a shaker to mineralize, resulting in a slurry; Step 4: Uniform foaming: Add the foaming agent to the slurry described in Step 3 and stir; the foaming agent is dodecyltrimethylammonium bromide, and its concentration in the slurry is 0.1-0.5 mmol / L; Step 5, Aerated Flotation: The collector is added to the slurry that has been stirred and foamed uniformly in Step 4, and then transferred to a flotation column equipped with a washing and defoaming device. An air pump is used to aerate the flotation column for flotation, and the washing and defoaming device is turned on to pump distilled water into the flotation column. The collector is dodecylamine, and the concentration of the collector in the slurry is 0.1-0.5 mmol / L. The aeration rate of the aerated flotation is 2-6 L / min. Step Six: Product Recovery: The recovered product in the collection tank is centrifuged and dried to recover lead metal; the recovered product is acidified with dilute nitric acid, and the Pb content in the acidified solution is measured. 2+ The concentration is used to evaluate flotation performance.

2. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, The isothermal oscillation culture described in steps one and two is at a temperature of 26–30°C, an oscillation rate of 140–160 rpm, and a culture time of 24–26 h.

3. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, The liquid culture medium described in steps one and two contains yeast extract at a concentration of 14–26 g / L, urea at a concentration of 18–24 g / L, ammonium chloride at a concentration of 8–14 g / L, manganese sulfate monohydrate at a concentration of 6–14 mg / L, nickel chloride hexahydrate at a concentration of 24–30 mg / L, and a pH value of 8–9.

4. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, In step two, the volume ratio of bacterial solution to liquid culture medium is 1:(100-1000), and the OD600 of the bacterial cement solution is 1.5-2.

0.

5. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, In step three, the lead concentration in the contaminated solution is 10–30 mmol / L. 5–15 mmol of urea is added to 100 mL of the contaminated solution, and 5–10 mL of bacterial cementing solution is added to 100 mL of the contaminated solution. The temperature for mineralization by shaking on a shaker is 26–30 °C, and the shaking rate is 140–160 rpm.

6. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, The flotation column with rinsing and defoaming device mentioned in step five refers to a flotation column with a rinsing port at the edge of the collection tank and a water pipe installed on the rinsing port. The water pipe is connected to a pump to pump distilled water into the flotation column.

7. The method for combined biomineralization-flotation recovery of lead metal from contaminated solutions according to claim 1, characterized in that, In step six, the flotation efficiency at 5 min, 10 min, and 20 min of the start of flotation was selected as the indicators for evaluating flotation performance.

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