Method for recovering lead metal in polluted solution through combination of biomineralization and flotation

Abstract

The invention discloses a method for recovering lead metal in a polluted solution through combination of biomineralization and flotation. The method comprises the following steps: 1, activating bacteria; 3, adding urea and a bacterial cementing solution into the pollution solution, and oscillating and mineralizing by a shaking table to obtain ore pulp; 4, adding a foaming agent into the ore pulp, and stirring; 5, a collecting agent is added into the evenly-foamed ore pulp, and then the ore pulp is transferred into a flotation column with a leaching and defoaming device for flotation; and 6, centrifuging the recovery product in the collecting tank, and drying to realize the recovery of lead metal. The method comprises the following steps: adding a bacterial liquid of bacillus pasteurii and urea into a polluted solution to generate mineralization reaction, converting lead ions in the solution into carbonate precipitates, and transferring the mineralized solution and a mineralized and precipitated mixture into a flotation column; and the lead in the solution is finally recycled in an air inflation mode of the air pump and the auxiliary effect of the flotation reagent.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental engineering, and in particular relates to a method for recovering lead metal in a polluted solution by combining biomineralization and flotation. Background Art

[0002] With the further development of social industrialization and science and technology, environmental pollution has gradually become the focus of social attention. Among them, the heavy metal pollution in soil and water bodies caused by human activities such as unreasonable industrial emissions, agricultural application, and atmospheric deposition is particularly serious. Heavy metals in soil and water bodies cannot be decomposed by microorganisms, so they will accumulate and transform into toxic methyl compounds. In addition, due to the presence of groundwater and rainfall, heavy metals in soil and water bodies have strong mobility, which will cause greater harm to the environment and organisms.

[0003] At present, the existing methods for the treatment of heavy metal pollution in water bodies are mainly divided into three categories: physical methods, chemical methods and biological methods. Most of the treatment directions are focused on converting free heavy metal ions into precipitates or other forms with lower solubility, making them less likely to migrate and thus limiting their pollution level. However, most of the existing technologies achieve the transformation of heavy metal forms by adding chemical reagents such as precipitants, oxidants, and reductants, and these added chemical reagents are prone to cause secondary pollution. Therefore, there are still certain limitations in the current treatment of heavy metal pollution in water bodies. Bioremediation technology is an emerging technology that uses the absorption and transformation of heavy metals by microorganisms or plants to achieve heavy metal removal. Among them, microbial induced carbonate precipitation (MICP) technology is a method that uses urease-producing bacteria to hydrolyze urea to produce CO 3 2- The ions combine with free heavy metal ions and convert them into carbonate precipitation, which limits their migration ability and thus reduces their pollution level. Based on the advantages of high efficiency, environmental protection and no secondary pollution, biological methods for remediating heavy metal-contaminated water bodies 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 precipitation by adding cultured Bacillus pasteurianus and urea to the contaminated solution, reducing its biological toxicity by limiting fluidity. However, the solidified lead metal still has the risk of secondary release over time; traditional flotation technology for treating heavy metal contaminated solutions usually uses chemical precipitation to precipitate heavy metal ions and then recovers them. The chemical reagents used may also cause secondary pollution to the environment.

[0004] Flotation technology is called flotation mineral separation technology. It is a technology that separates minerals based on the difference in hydrophobicity of the mineral surface. By adding flotation agents such as frothers and collectors, the target minerals are attached to the bubbles generated by the frothers in the slurry and are taken out of the flotation tank with aeration, thereby recovering the target minerals. This technology is currently widely used in the separation of metal minerals, non-metallic minerals and chemical raw materials in industry. There is less research on the control of heavy metal pollution. In addition, for heavy metal pollution in water bodies, chemical reagents are added to convert heavy metal ions in the water body into precipitated forms for recovery, which still has a high risk of secondary pollution. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for recovering lead metal in a contaminated solution by combining biomineralization and flotation in view of the deficiencies of the above-mentioned prior art. The method is to add the bacterial solution of Bacillus pasteurianus and urea to the contaminated solution to cause a mineralization reaction, convert the lead ions in the solution into carbonate precipitates, and then transfer the solution after the mineralization and the mixture of the mineralized precipitates to a flotation column, and finally recover the lead in the solution by means of air pump inflation and the auxiliary effect of flotation reagents.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for recovering lead metal from a contaminated solution by combining biomineralization and flotation, characterized in that it comprises the following steps:

[0007] Step 1: Bacterial activation: placing the freeze-dried powder of Bacillus pasteurianus in a liquid culture medium, culturing with constant temperature and shaking to obtain activated bacteria, and storing them;

[0008] Step 2: bacterial expansion: the bacterial solution stored in step 1 is mixed with the liquid culture medium, and cultured on a shaker at a constant temperature to obtain a bacterial agglomerate;

[0009] Step 3, inducing mineralization: adding urea and the bacterial cementing solution described in step 2 to the contaminated solution, shaking on a shaker for mineralization, and obtaining a slurry;

[0010] Step 4: Uniform foaming: adding a foaming agent to the slurry in step 3 and stirring;

[0011] Step 5, aeration flotation: add the collector to the slurry that is uniformly foamed after stirring in step 4, and then transfer it to a flotation column with a leaching and defoaming device, use an air pump to aerate the flotation column for flotation, and turn on the leaching and defoaming device to pump distilled water into the flotation column;

[0012] Step 6: Product recovery: The recovered product in the collection tank is centrifuged and dried to achieve the recovery of lead metal; the recovered product is acidified with dilute nitric acid and the Pb content in the acidified solution is measured. 2+The flotation performance was evaluated by the concentration.

[0013] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization-flotation is characterized in that the culture temperature of the constant temperature shaking culture in step one and step three is 26-30°C, the shaking rate is 140-160rpm, and the culture time is 24-26h.

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

[0015] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization-flotation is characterized in that the volume ratio of the bacterial solution to the liquid culture medium in step 2 is 1:(100-1000), and the OD600 of the bacterial cementing solution is 1.5-2.0.

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

[0017] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization-flotation is characterized in that the foaming agent in step 4 is dodecyltrimethylammonium bromide, and its concentration in the ore pulp is 0.1-0.5 mmol / L.

[0018] The above-mentioned method for recovering lead metal from a contaminated solution by combined biomineralization-flotation is characterized in that the flotation column with a rinsing and defoaming device in step five refers to a flushing port opened at the edge of the collecting tank of the flotation column, and a water pipe is installed on the flushing port, and 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-flotation is characterized in that the collector in step five is dodecylamine, and the concentration of the collector in the ore pulp is 0.1-0.5 mmol / L.

[0020] The above-mentioned method for recovering lead metal from a contaminated solution by combining 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 recovering lead metal from a contaminated solution by combining biomineralization and flotation is characterized in that in step six, the flotation efficiency at 5 minutes, 10 minutes and 20 minutes after the start of flotation is respectively selected as an indicator for evaluating the flotation performance.

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

[0023] 1. The method of the present invention realizes the recovery of lead metal in the contaminated solution by combining microbial induced carbonate precipitation technology with flotation technology, and replaces the chemical precipitation method used in the traditional flotation process with biological induced precipitation, thereby reducing the risk of secondary pollution that may be caused by adding chemical reagents, and at the same time overcoming the problem of low economic benefits derived from adding a large amount of chemical precipitants. Subsequently, the mineralized product generated after the lead ions in the contaminated solution are solidified is floated to realize the recovery of lead metal in the contaminated solution, which has significant economic benefits.

[0024] 2. The present invention adds a leaching and defoaming device to the traditional flotation column, which can quickly defoam the foam adsorbed with the target mineral in the recovery tank after floating. Compared with the traditional flotation column that uses a scraper to scrape the foam, the addition of the leaching and defoaming device can effectively prevent the foam from overflowing from the flotation tank, thereby facilitating recovery and reducing the risk of resource waste.

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

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure 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 of Example 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 the molecular dynamics simulation result of the adsorption of the flotation agent on the surface of the mineralized product in the combination of the cationic frother and the cationic collector of Example 1 of the present invention.

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

[0034] Description of reference numerals:

[0035] 1—flotation column; 2—collection tank; 3—flushing port; 4—water pipe;

[0036] 5—Pump; 6—Distilled water. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the embodiments. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments, unless otherwise specified, can be obtained from commercial channels.

[0038] The present invention is specifically described below in conjunction with embodiments, but the following description is not intended to limit the present invention.

[0039] The flotation column with a rinsing and defoaming device described in the following embodiments refers to a flotation column 1 having a flushing port 3 at the edge of a collecting tank 2, and a water pipe 4 installed on the flushing port 3. The water pipe 4 is connected to a pump 5 for pumping distilled water 6 into the flotation column. The specific structure is shown in FIG. Figure 1 .

[0040] Example 1

[0041] The method of biomineralization-flotation combined recovery of lead metal in a contaminated solution of this embodiment comprises the following steps:

[0042] Step 1, bacterial activation, specifically comprising: placing 1.0 mg of lyophilized powder of Bacillus pasteurianus in a 250 mL conical flask filled with 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing the flask in a constant temperature shaking incubator with a culture temperature set at 30° C. and an oscillation rate of 140 rpm for 26 hours to obtain activated bacteria, mixing the activated bacteria with glycerol at a volume ratio of 7:3 and freezing and storing the mixture at a temperature of -20° C.; the bacteria are Bacillus pasteurianus, purchased from China General Microbiological Culture Collection Center (CGMCC), with a collection number of CGMCC 1.3687;

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

[0044] Step 2, bacterial expansion, specifically comprising: adding the bacterial solution preserved in step 1 to a liquid culture medium, shaking and culturing in a constant temperature incubator at a shaking rate of 140 rpm and a temperature of 30° C. for 26 hours to obtain a bacterial agglutination liquid 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 described in step 1;

[0045] Step 3: Inducing mineralization, specifically comprising: adding 10 mmol urea and 7 mL of the bacterial cementing solution described in step 3 to a solution containing 30 mmol Pb 2+ The mixture was placed in 100 mL of deionized water and subjected to shaking on a shaker for 24 h at 30° C. and 140 rpm to obtain a slurry containing lead carbonate precipitate;

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

[0047] Step 5, aeration flotation, specifically comprising: adding 0.5 mL of a cationic collector solution with a concentration of 0.1 mol / L into the slurry that is uniformly foamed after stirring in step 4, and then transferring it to a flotation column with a leaching and defoaming device, starting an air pump for aeration flotation, and starting the leaching and defoaming device to pump distilled water into the flotation column to quickly defoam the foam adsorbed with the target mineral in the recovery tank by floating to the recovery tank, effectively preventing the foam from overflowing from the flotation tank; the cationic collector is dodecylamine; the aeration rate of the aeration flotation is 4 L / min;

[0048] Step 6, product recovery, specifically comprising: collecting the recovered product in the collection tank of the flotation column into a beaker through the drainage port, then centrifuging the solid-liquid mixture in the beaker, drying the solid matter obtained by centrifugation, and finally recovering the lead metal in the solution; selecting the flotation efficiency at 5min, 10min and 20min from the start of flotation as indicators for evaluating the flotation performance, and acidifying the recovered product with dilute nitric acid. The specific method is: adding 10% dilute nitric acid to the recovered product under stirring until the solution becomes clear, measuring the Pb in the acidified solution 2+ The flotation performance was evaluated by the concentration.

[0049] Comparative Example 1

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

[0055] Example 2

[0056] The method of biomineralization-flotation combined recovery of lead metal in a contaminated solution of this embodiment comprises the following steps:

[0057] Step 1, bacterial activation, specifically comprising: placing 1.0 mg of lyophilized powder of Bacillus pasteurianus in a 250 mL conical flask filled with 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing the flask in a constant temperature shaking incubator with a culture temperature set at 26° C. and an oscillation rate of 160 rpm for 24 hours to obtain activated bacteria, mixing the activated bacteria with glycerol at a volume ratio of 7:3 and freezing and storing the mixture at a temperature of -20° C.; the bacteria are Bacillus pasteurianus, purchased from China General Microbiological Culture Collection Center (CGMCC), with a collection number of CGMCC 1.3687;

[0058] The liquid culture medium has a yeast extract content of 14 g / L, a urea content of 18 g / L, an ammonium chloride content of 8 g / L, a manganese chloride monohydrate content of 6 mg / L, a nickel chloride hexahydrate content of 24 mg / L, a pH value of 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, specifically comprising: adding the bacterial solution preserved in step 1 to a liquid culture medium, shaking and culturing in a constant temperature incubator at a shaking rate of 160 rpm and a temperature of 26° C. for 24 hours to obtain a bacterial agglutination 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 described in step 1;

[0060] Step 3: Inducing mineralization, specifically comprising: adding 5 mmol urea and 5 mL of the bacterial cementing solution described in step 3 to a solution containing 10 mmol Pb 2+The ore was then added to 100 mL of deionized water and mineralized on a shaker at 26°C and 140 rpm for 24 h to obtain a slurry containing lead carbonate precipitate;

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

[0062] Step 5, aeration flotation, specifically comprising: adding 0.3 mL of a cationic collector solution with a concentration of 0.1 mol / L into the slurry that is uniformly foamed after stirring in step 4, and then transferring it to a flotation column with a leaching and defoaming device, starting an air pump for aeration flotation, and opening the leaching and defoaming device to pump distilled water into the flotation column to quickly defoam the foam adsorbed with the target mineral in the recovery tank by floating to the recovery tank, effectively preventing the foam from overflowing from the flotation tank; the cationic collector is dodecylamine; the aeration rate of the aeration flotation is 2 L / min;

[0063] Step six, product recovery, specifically includes: collecting the recovered product in the collection tank of the flotation column back into the beaker through the drainage port, then centrifuging the solid-liquid mixture in the beaker, drying the solid matter obtained by centrifugation, and finally recovering the lead metal in the solution.

[0064] Example 3

[0065] The method of biomineralization-flotation combined recovery of lead metal in a contaminated solution of this embodiment comprises the following steps:

[0066] Step 1, bacterial activation, specifically comprising: placing 1.0 mg of lyophilized powder of Bacillus pasteurianus in a 250 mL conical flask filled with 100 mL of liquid culture medium, sealing the flask with a biological sealing film, and culturing the flask in a constant temperature shaking incubator with a culture temperature set at 28° C. and a shaking rate of 150 rpm for 25 hours to obtain activated bacteria, mixing the activated bacteria with glycerol at a volume ratio of 7:3 and freezing and storing the mixture at a temperature of -20° C.; the bacteria are Bacillus pasteurianus, purchased from China General Microbiological Culture Collection Center (CGMCC), with a collection number of CGMCC 1.3687;

[0067] The liquid culture medium has a yeast extract content of 26 g / L, a urea content of 24 g / L, an ammonium chloride content of 14 g / L, a manganese chloride monohydrate content of 14 mg / L, a nickel chloride hexahydrate content of 30 mg / L, a pH value of 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, specifically comprising: adding the bacterial solution preserved in step 1 to a liquid culture medium, shaking and culturing in a constant temperature incubator at a shaking rate of 150 rpm and a temperature of 28° C. for 25 hours to obtain a bacterial agglutination 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 described in step 1;

[0069] Step 3: Inducing mineralization, specifically comprising: adding 15 mmol urea and 10 mL of the bacterial cementing solution described in step 3 to a solution containing 20 mmol Pb 2+ The ore was then added to 100 mL of deionized water and mineralized on a shaker at 28°C and 150 rpm for 24 h to obtain a slurry containing lead carbonate precipitate;

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

[0071] Step 5, aeration flotation, specifically comprising: adding 0.1 mL of a cationic collector solution with a concentration of 0.1 mol / L into the slurry that is uniformly foamed after stirring in step 4, and then transferring it to a flotation column with a leaching and defoaming device, starting an air pump for aeration flotation, and starting the leaching and defoaming device to pump distilled water into the flotation column to quickly defoam the foam adsorbed with the target mineral in the recovery tank by floating to the recovery tank, effectively preventing the foam from overflowing from the flotation tank; the cationic collector is dodecylamine; the aeration rate of the aeration flotation is 6 L / min;

[0072] Step six, product recovery, specifically includes: collecting the recovered product in the collection tank of the flotation column back into the beaker through the drainage port, then centrifuging the solid-liquid mixture in the beaker, drying the solid matter obtained by centrifugation, and finally recovering the lead metal in 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 Figure 2-5:Frothers and collectors are flotation agents used in flotation, and they play different roles in flotation. According to the different charges carried by their polar groups, frothers and collectors can be divided into anionic and cationic types. Frothers reduce the gas-liquid interfacial tension and increase the dispersion of air in the slurry to generate more tiny bubbles in the slurry. Then the collector selectively adsorbs on the surface of the floating mineral to form a hydrophobic layer, so that the hydrophobic mineral particles attach to the bubbles and float to the foam product to achieve the flotation of the mineral. In flotation, only by combining the two and using them in their respective functions can a more ideal flotation effect be achieved. Figure 2 to Figure 5 The results are as follows: the flotation efficiency of lead in the contaminated solution using a combination of a cationic frother × a cationic collector (cation × cation), an anionic frother × anionic collector (anion × anion), a cationic frother × anionic collector (cation × anion), and an anionic frother × a cationic collector (anion × cation). Figure 2 It can be seen that Example 1 of the present invention can achieve a good flotation efficiency (up to 84.5%), which is far superior to the effects of the other three combinations. This phenomenon is mainly caused by the fact that the flotation reagents in the combination of Example 1 carry charges of the same valence, and there is an electrostatic repulsion between the reagents, so the flotation reagents are in a dispersed state; in addition, the negatively charged lead carbonate can be well adsorbed with the positively charged flotation reagent due to the effect of electrostatic attraction. The combined effect of the two leads to a better flotation effect in the combination, such as Figure 6 shown.

[0075] according to Figure 3 It can be seen that under the combination of anion × anion, as the flotation time increases, the final flotation effect is poor, with only 19.9% ​​flotation efficiency. This phenomenon is mainly caused by the pH corresponding to the zero point of lead carbonate (Zeta potential is 0) is 4.8, and for MICP technology, the hydrolysis of urea releases OH-, which will cause the pulp to be alkaline. Therefore, the surface charge of lead carbonate in the pulp is negative. Due to the electrostatic effect, it will have a strong repulsion effect with the negatively charged anionic flotation reagent of the polar base, resulting in poor flotation effect. Figure 4 and Figure 5 It can be seen that in the combination of cation × anion and anion × cation, even if a cationic flotation agent is used, the final flotation effect is still poor, only 18.5% and 20.4% respectively. This phenomenon may be due to the fact that the electrostatic force between the flotation agents with different charges is greater than the effect between the flotation agents and the mineral surface when the two flotation agent combinations are used, resulting in the flotation agents preferentially combining to form micelles and failing to effectively attach to the mineral surface to exert their effects. The results obtained by modeling the mineral crystal surface and flotation agent molecules based on molecular dynamics and simulating the adsorption of the two in the actual slurry solution environment are as follows: Figure 7As shown, it can be observed that the flotation agents combine with each other to form micelles, which makes them unable to play their respective roles normally, thus resulting in poor flotation effect.

[0076] The present invention combines microbial induced carbonate precipitation technology with flotation technology to achieve the recovery of lead metal in the contaminated solution, and replaces the chemical precipitation method used in the traditional flotation process with biological induced precipitation, thereby reducing the risk of secondary pollution that may be caused by adding chemical reagents, and at the same time overcoming the problem of low economic benefits derived from adding a large amount of chemical precipitants. Subsequently, the mineralized product generated after the lead ions in the contaminated solution are solidified is floated to achieve the recovery of lead metal in the contaminated solution, which has significant economic benefits.

[0077] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for recovering lead metal from a contaminated solution by combining biomineralization and flotation, characterized in that: The following steps are involved: Step 1: Bacterial activation: placing the freeze-dried powder of Bacillus pasteurianus in a liquid culture medium, culturing with constant temperature and shaking to obtain activated bacteria, and storing them; Step 2: bacterial expansion: the bacterial solution stored in step 1 is mixed with the liquid culture medium, and cultured on a shaker at a constant temperature to obtain a bacterial agglomerate; Step 3, inducing mineralization: adding urea and the bacterial cementing solution described in step 2 to the contaminated solution, shaking on a shaker for mineralization, and obtaining a slurry; Step 4: Uniform foaming: adding a foaming agent to the slurry in step 3 and stirring; Step 5, aeration flotation: add the collector to the slurry that is uniformly foamed after stirring in step 4, and then transfer it to a flotation column with a leaching and defoaming device, use an air pump to aerate the flotation column for flotation, and turn on the leaching and defoaming device to pump distilled water into the flotation column; Step 6: Product recovery: The recovered product in the collection tank is centrifuged and dried to achieve the recovery of lead metal; the recovered product is acidified with dilute nitric acid and the Pb content in the acidified solution is measured. 2+ The flotation performance was evaluated by the concentration of 2. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The culture temperature of the constant temperature shaking culture in step 1 and step 3 is 26-30° C., the shaking rate is 140-160 rpm, and the culture time is 24-26 h.

3. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The liquid culture medium in step 1 and step 3 has a yeast extract content of 14-26 g / L, a urea content of 18-24 g / L, an ammonium chloride content of 8-14 g / L, a manganese sulfate monohydrate content of 6-14 mg / L, a nickel chloride hexahydrate content of 24-30 mg / L, and a pH value of 8-9.

4. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The volume ratio of the bacterial solution to the liquid culture medium in step 2 is 1: (100~1000), the OD600 of bacterial agglutination fluid is 1.5~2.

0.

5. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The lead concentration in the contaminated solution in step 3 is 10-30 mmol / L, 5-15 mmol 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, the temperature of the shaker oscillation mineralization is 26-30° C., and the oscillation rate is 140-160 rpm.

6. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The foaming agent in step 4 is dodecyltrimethylammonium bromide, and its concentration in the ore pulp is 0.1-0.5 mmol / L.

7. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The flotation column with a rinsing and defoaming device described in step 5 refers to a flushing port opened at the edge of the collecting tank of the flotation column, and a water pipe is installed on the flushing port. The water pipe is connected to a pump to pump distilled water into the flotation column.

8. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The collector in step five is dodecylamine, and the concentration of the collector in the ore pulp is 0.1-0.5 mmol / L.

9. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: The inflation rate of the inflation flotation in step 5 is 2 to 6 L / min.

10. The method for recovering lead metal from a contaminated solution by biomineralization-flotation combined with flotation according to claim 1, characterized in that: In step six, the flotation efficiencies at 5 minutes, 10 minutes and 20 minutes after the start of flotation are respectively selected as indicators for evaluating the flotation performance.

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