Green and efficient method for resource utilization of lead-selenium-mercury-containing acid mud

Abstract

The invention discloses a green and efficient method for resource utilization of acid mud containing lead, selenium and mercury, and belongs to the technical field of solid waste treatment. The method comprises the following steps: leaching the lead-selenium-mercury-containing acid mud with a sodium chloride solution to obtain lead-removed slag and lead-containing waste liquid, leaching the lead-removed slag with dilute sulfuric acid to obtain zinc-containing waste liquid and selenium-mercury slag, carrying out hydrolytic precipitation on the zinc-containing waste liquid to obtain zinc-containing precipitate and alkaline waste liquid, carrying out oxidation acid leaching on the selenium-mercury slag to obtain selenium-mercury leaching liquid, carrying out neutralization precipitation on the selenium-mercury leaching liquid, and carrying out solid-liquid separation to obtain the selenium-mercury-containing acid mud. Carrying out acidification and reduction precipitation on the selenium-containing solution to obtain crude selenium precipitation and acidic waste liquid; mixing the lead-containing waste liquid, the alkaline waste liquid and the acid waste liquid, and neutralizing and precipitating to obtain lead-containing precipitate; according to the method, selenium, mercury and lead in the selenium-mercury acid mud are efficiently separated and recycled, wastewater generated in the whole technological process is recycled, and the method is environmentally friendly, low in agent consumption, mild in condition, low in cost and beneficial to large-scale application.

Description

Technical Field

[0001] The invention relates to a method for treating acid mud, in particular to a green and efficient method for resource utilization of lead-selenium-mercury acid mud, belonging to the technical field of hazardous waste resource treatment. Background Art

[0002] During the acid production process of the lead and zinc smelting system, hazardous waste acid sludge contains valuable metals such as selenium and mercury. This acid sludge is extremely harmful to the environment, so it is very necessary to utilize this acid sludge as a resource. Extracting selenium, mercury and other valuable metals from the acid sludge can not only effectively treat hazardous waste, but also recover the valuable metals therein to achieve additional economic benefits.

[0003] At present, the general treatment processes for acid sludge produced by lead and zinc smelters include pyrometallurgical technology and hydrometallurgical technology. For high-selenium and low-mercury selenium-mercury acid sludge, the existing technology generally uses hydrometallurgical technology to separate and extract selenium and mercury from the acid sludge. Among them, the methods for extracting selenium and mercury from acid sludge by hydrometallurgical technology include oxidation leaching, oxygen pressure alkali leaching, etc. The principle is to leach the selenium and mercury elements in the acid sludge into the solution, and use alkali precipitation and acidification precipitation to achieve selenium and mercury separation and extraction. However, there are some common problems with hydrometallurgical technology, such as the generation of a large amount of wastewater, the generation of some toxic and corrosive gases during leaching, high leaching temperature, and the doping of other metal ions into the separation system.

[0004] A Chinese patent (publication number: CN108004408A) discloses a method for separating and recovering selenium, mercury and lead from lead-containing acid mud. The principle is to perform pressurized oxidation treatment on the acid mud so that mercury and lead are leached into the solution, and selenium is retained in the acid mud to achieve the separation of selenium. The lead-mercury separation uses copper scraps for replacement to produce insoluble copper-mercury compounds and lead-containing solutions, thereby achieving lead-mercury separation. However, the copper scrap replacement agent used in this process is itself a valuable metal, and a new metal element is introduced into the process system, so it does not have advantages in terms of cost and environment. A Chinese patent (publication number: CN115341097A) discloses a method for hydrometallurgical treatment of high-arsenic and low-mercury selenic acid mud. The principle is to leach selenium, mercury and other elements through chlorination leaching, and to separate selenium and mercury by reduction and sulfide precipitation. However, the oxidant sodium chlorate used in this process will produce toxic and corrosive chlorine gas during the reaction, so it may corrode the equipment and is not very environmentally friendly. A Chinese patent (publication number: CN106756038A) discloses a method for separating selenium and mercury from acid mud in a sulfuric acid system of copper, lead and zinc smelting. The principle is to convert the mercury element in the acid mud into mercury oxide alkaline leaching residue by oxygen pressure alkaline leaching under high temperature environment, and the selenium element enters the alkaline leaching liquid, and the selenium and mercury are separated by solid-liquid separation. However, a large amount of wastewater generated by this process needs to be further treated and discharged only after the treatment meets the standards. This process requires a large amount of clean water, and the wastewater generated is not circulated. On the other hand, the leaching temperature of this process needs to reach above 160°C, so the energy consumption of this process is relatively high. A Chinese patent (publication number: CN104561558A) discloses a method for treating selenium-mercury acid mud. The principle uses chlorination leaching-oxidation acid leaching to separate selenium and mercury elements and remove impurity lead, but the entire process does not involve the process of recycling wastewater. The step of producing NaCl by crystallization and evaporation of waste liquid mentioned therein is a high energy consumption process, so this process does not have advantages in terms of energy consumption and environmental protection.

[0005] It can be seen that there are still some technical points that need to be improved in the wet technology treatment of selenomercuric acid sludge. Summary of the invention

[0006] In view of the technical problems that the existing hydrometallurgical technology requires high-temperature leaching, generates corrosive gases during leaching, and wastewater is difficult to recycle when extracting selenium and mercury elements from lead-containing selenium mercury acid mud, the purpose of the present invention is to provide a green and efficient method for resource utilization of lead-containing selenium mercury acid mud. The method can not only realize the efficient separation and recovery of selenium, mercury and lead in the lead-containing selenium mercury acid mud, thereby achieving the purpose of resource utilization of the lead-containing selenium mercury acid mud, but also the wastewater generated in the whole process is reused, which is green and environmentally friendly. At the same time, the reagent consumption is low, the conditions are mild, the cost is low, and it is conducive to large-scale treatment.

[0007] In order to achieve the above technical objectives, the present invention provides a green and efficient method for resource utilization of lead-containing selenomercuric acid mud, which comprises the following steps: 1) Leaching the lead-containing selenomercuric acid mud with a sodium chloride solution to obtain lead-removing slag and lead-containing waste liquid; 2) Leaching the lead removal slag with dilute sulfuric acid to obtain zinc-containing waste liquid and selenium-mercury slag; 3) hydrolyzing and precipitating the zinc-containing waste liquid to obtain zinc-containing precipitate and alkaline waste liquid; 4) subjecting the selenium-mercury slag to oxidative acid leaching to obtain a selenium-mercury leaching solution; 5) neutralizing and precipitating the selenium-mercury leaching solution to obtain mercuric oxide precipitate and selenium-containing solution; 6) Acidifying and reducing the selenium-containing solution to obtain crude selenium precipitate and acidic waste liquid; 7) The lead-containing waste liquid, alkaline waste liquid and acidic waste liquid are mixed for neutralization and precipitation to obtain lead-containing precipitate.

[0008] Lead-selenomercuric acid mud mainly contains valuable metals such as selenium, mercury, zinc and lead. Selenium and mercury mainly exist in the form of HgSe, while lead and zinc mainly exist in the form of PbSO 4 According to the characteristics of the existence of ZnS and ZnS, the present invention adopts different leaching methods to achieve step-by-step leaching and separation and recovery according to the different leaching difficulties of these valuable metal compounds. First, the acid mud is leached with sodium chloride solution, mainly to leach the main impurity lead in the acid mud to obtain lead-containing waste liquid, and the reaction formula is as follows: PbSO 4 (s)+2NaCl=PbCl 2 +Na 2 SO 4 Secondly, the leached residue is further leached with dilute sulfuric acid, mainly to selectively leach the zinc sulfide impurity zinc, ZnS+ H 2 SO 4 =H 2 S+ZnSO 4 , and zinc-containing waste liquid is obtained. Again, the leached residue is further leached with oxidative acid, mainly to leach out the main components of selenium and mercury, and obtain selenium and mercury leaching solution. The main reaction formula is as follows: HgSe(s)+ 2HCl+H 2 O 2 =H 2 SeO 3 +HgCl 2 +H 2 In the above leaching process, the zinc-containing waste liquid is hydrolyzed and precipitated by alkali to obtain zinc hydroxide precipitate. The zinc-containing precipitate can be directly sent to the smelting system, and the precipitated waste liquid is alkaline waste liquid. The main reaction formula is as follows: ZnSO 4 +2NaOH=Zn(OH) 2 +Na 2 SO 4The selenium-mercury leaching is first neutralized with alkali to obtain HgO precipitation, and then further acidified and reduced to precipitate crude selenium precipitation, thereby achieving the separation of selenium and mercury. The precipitation waste liquid is alkaline waste liquid. The main reaction formula is as follows: H 2 SeO 3 +HgCl 2 +2NaOH=Na 2 SeO 3 +HgO+ 2NaCl+2H 2 O; Na 2 SeO 3 +H 2 SO 4 + Na 2 SO 3 =Se+Na 2 SO 4 +NaHSO 3 The main components of the obtained lead-containing waste liquid are lead chloride and sodium sulfate, while the main components of the alkaline waste liquid are sodium hydroxide and sodium sulfate, and the acidic waste liquid contains sulfuric acid, sodium bisulfite and sodium sulfate. The present invention ingeniously treats the three waste liquids comprehensively, neutralizes the alkaline waste liquid and the acidic waste liquid, and uses high-concentration sulfate to convert the lead chloride in the lead-containing waste liquid into lead sulfate precipitation. The main reaction formula is as follows: 4NaOH+H 2 SO 4 =2NaOH+Na 2 SO 4 +2H 2 O; Na 2 SO 4 +2NaHSO 3 +2PbCl 2 = Pb(HSO 3 ) 2 +4NaCl+PbSO 4 In summary, the present invention realizes the efficient separation and recovery of valuable metals such as selenium, mercury, zinc and lead in selenomercuric acid mud, and the acid and alkali waste liquids are recycled.

[0009] As a preferred solution, the lead-selenomercuric acid mud mainly contains HgSe, PbSO 4 The mass content of mercury is 10-20%; the mass content of selenium is 40-60%; the mass content of lead is 10-20%; the mass content of zinc is 0.5-2%. The water content of lead-selenomercuric acid mud is 15-30%.

[0010] As a preferred solution, in step 1), the leaching conditions are: the concentration of the sodium chloride solution is 200-400 g / L, the liquid-to-solid ratio is 10-15 mL / g, the leaching temperature is 50-80° C., and the leaching time is 1-2 hours. Under the preferred leaching conditions, lead sulfate can be leached with high selectivity by utilizing the characteristics of mercuric selenide and zinc sulfide being insoluble in sodium chloride solution.

[0011] As a preferred solution, in step 2), the leaching conditions are: the leaching conditions are: the mass percentage concentration of dilute sulfuric acid is 3-8%, the liquid-to-solid ratio is 10-20 mL / g, the leaching temperature is 25-60° C., and the leaching time is 0.5-1.0 h. Under the preferred leaching conditions, mercuric selenide is selectively leached by taking advantage of its insolubility in dilute acid.

[0012] As a preferred solution, in step 3), the hydrolysis precipitation condition is: sodium hydroxide is used to adjust the pH to between 9 and 12. Under the preferred hydrolysis conditions, zinc is precipitated in the form of zinc hydroxide.

[0013] As a preferred solution, in step 4), the conditions for oxidative acid leaching are: using hydrogen peroxide as the oxidant and hydrochloric acid as the leaching agent, in the leaching system, the mass percentage concentration of hydrochloric acid is 2-5%, the mass percentage concentration of hydrogen peroxide is 3-5%, the leaching temperature is 25-30°C, and the leaching time is 1-2h.

[0014] As a preferred solution, in step 5), the conditions for neutralization precipitation are: using sodium hydroxide to adjust the pH to between 11 and 13. Under alkaline conditions, mercuric chloride is converted into mercuric oxide precipitation, and the recovery rate of mercury can reach 97-99%. The HgO precipitate can be sent to a roasting rotary kiln for roasting and condensation to obtain a crude mercury product.

[0015] As a preferred solution, in step 6), the acidification condition is: using dilute sulfuric acid to adjust the pH to between 0 and 2.

[0016] As a preferred solution, in step 6), the reduction precipitation conditions are: sodium sulfite is used as a reducing agent, the amount of the reducing agent is measured when the pH no longer increases during the reduction process, the reduction temperature is 60-90°C, and the reduction time is 1-3h. After oxidative leaching and neutralization of mercury precipitation, selenium mainly exists in the form of sodium selenate, and is easily reduced to elemental selenium under acidic conditions. The selenium grade of elemental selenium is 93-97%. During the reduction process, the addition of sodium sulfite to the reaction will cause the pH to increase slightly. This is because hydrogen ions are consumed in the process of sodium sulfite reducing selenous acid. Therefore, when the pH does not change significantly, the surface reduction reaction is completed and the addition of sodium sulfite can be stopped.

[0017] As a preferred solution, in step 7), the pH of the neutralization precipitation of the lead-containing waste liquid, the alkaline waste liquid and the acidic waste liquid is controlled to be neutral. The lead-containing precipitate obtained by the neutralization precipitation is sent back to the smelting system, and the final waste liquid contains sodium chloride salt, which can be returned to the lead leaching process.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: (1) The present invention utilizes the hazardous waste lead-seleno-mercuric acid sludge generated in the smelting system as a resource, and can efficiently separate and recover valuable metals such as selenium, mercury, zinc and lead therein, thereby bringing additional economic benefits to the smelting enterprise.

[0019] (2) In the process of treating lead-seleno-mercuric acid sludge, all intermediate wastewater and final wastewater are recycled, which not only reduces the consumption of acid and alkali, but also does not generate any secondary harmful wastewater. The present invention has the characteristics of being green, low-cost, and low-energy.

[0020] (3) The present invention treats acidic wastewater, alkaline wastewater and lead-containing waste liquid together, which not only does not require additional consumption of acid and alkali reagents, but also can reduce sulfate ions in the solution, so that the waste liquid can be recycled for the lead leaching process of lead-selenomercuric acid sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the process flow chart for resource treatment of lead-seleno-mercuric acid sludge.

[0022] Figure 2 This is the XRD diagram of lead-selenomercuric acid mud.

[0023] Figure 3 This is the XRD pattern of HgO.

[0024] Figure 4 It is the XRD pattern of gray Se. DETAILED DESCRIPTION

[0025] The present invention is explained in detail through specific implementation schemes, but the protection scope of the present invention is not limited to the following operation contents.

[0026] Example 1 The lead-containing selenium mercuric acid mud for resource utilization was from the lead smelting system, and its water content was 28.6%. The content of main elements and XRD phase analysis were shown in Table 1 and Figure 2 . In the experiment, 100 g of dried lead-selenomercuric acid mud was taken.

[0027]

[0028] (1) Impurity removal: Since the lead-containing selenomercuric acid mud contains impurities of lead sulfate and zinc sulfide, sodium chloride solution is used to remove impurities. Sodium chloride solution can convert lead sulfate into a soluble complex of lead, while zinc sulfide and selenium mercury elements cannot be leached out by sodium chloride. Through solid-liquid separation, lead removal slag and lead-containing waste liquid are obtained. The main element composition of the lead removal slag is shown in Table 1; the concentration of the sodium chloride solution is 250g / L, and the leaching temperature is 70℃. The leaching time is 1.5h, and the liquid-solid ratio is 12mL / g. Subsequently, dilute sulfuric acid is used to leach the lead removal slag, mainly leaching zinc sulfide, to obtain selenium mercury slag and zinc-containing waste liquid. The leaching conditions are: 5% sulfuric acid, liquid-solid ratio: 10mL / g, temperature: 40℃, leaching time: 0.5h. NaOH is added to the zinc-containing waste liquid to make the pH between 9 and 12, and waste liquid and zinc-containing precipitate are obtained. The zinc-containing precipitate is sent to the smelting system.

[0029] (2) Oxidative leaching: After impurities are removed, the remaining selenium-mercury slag is subjected to oxidative leaching. In the leaching system, the liquid-to-solid ratio is 15 mL / g, the mass percentage of hydrogen peroxide is 3.2%, the mass percentage of hydrochloric acid is 2.3%, the leaching temperature is 28 °C, the leaching time is 1.5 h, and the leaching rate of selenium and mercury is 99%.

[0030] (3) Mercury precipitation: After leaching, the selenium mercury solution was subjected to alkali precipitation, and the pH was maintained at about 12. 18.1 g of orange-yellow mercuric oxide precipitate was obtained. The theoretical extraction of mercury was 16.7 g, and 100 g of dried acid mud contained 16.65 g of mercury, indicating that the mercuric oxide precipitate contained extremely trace impurities. The recovery rate of mercury was nearly 100%. The XRD phase analysis diagram of HgO is shown in Figure 3 ; (4) Reduction precipitation of selenium: After mercury precipitation, solid-liquid separation is performed to obtain a selenium-containing solution, which is acidified to a pH of 0-1 and maintained at all times. Sodium sulfite is added to reduce and precipitate selenium. When the pH does not change significantly, the addition of sodium sulfite is stopped. The reduction time is 2 h and the reduction temperature is 70 °C. 46.1 g of gray selenium precipitate is obtained, and 100 g of dried acid mud contains 48.90 g of selenium. Therefore, the recovery rate of selenium is 94.3%. The XRD phase analysis diagram of gray Se is shown in Figure 4 ; (5) Mixed neutralization: The acidic wastewater generated after the lead-containing waste liquid and selenium and mercury extraction are mixed and neutralized to neutrality, and then the lead-containing precipitate and neutralized wastewater are obtained through solid-liquid separation. The lead-containing precipitate is sent to the smelting system. The wastewater mainly contains NaCl and Na 2 SO 4 , so it can be reused in the impurity removal step.

[0031] The above content is a detailed description of the present invention, but the present invention is not limited to the above content. Since the components of the selenomergic acid sludge produced by different smelters are quite different, other steps can be added based on the present invention when processing the produced selenomergic acid sludge to ensure the smooth extraction of selenium and mercury.

[0032] Example 2 Example The lead-containing selenomercuric acid mud for resource utilization comes from the lead smelting system, and its water content is 31.9%. The main phases are HgSe and Se. The composition content is shown in Table 2. In the experiment, 100 g of dried lead-containing selenomercuric acid mud was taken.

[0033]

[0034] (1) Impurity removal: Lead-containing selenium-mercuric acid mud is removed by high-concentration sodium chloride solution. Sodium chloride solution can convert lead sulfate into soluble complexes of lead, while HgSe, Se and ZnS in the acid mud cannot be leached by sodium chloride. After solid-liquid separation, lead removal slag and lead-containing waste liquid are obtained. The main element composition of the lead removal slag is shown in Table 2. The concentration of sodium chloride solution is 300g / L, and the leaching temperature is 80℃. The leaching time is 2h, and the liquid-solid ratio is 10mL / g. Subsequently, dilute sulfuric acid is used to remove zinc from the lead removal slag and obtain selenium-mercuric slag and zinc-containing waste liquid. The leaching conditions are: 4% sulfuric acid, liquid-solid ratio: 10mL / g, temperature: 50℃, and leaching time: 1h. NaOH is added to the zinc-containing waste liquid to make the pH between 9 and 12, and waste liquid and zinc-containing precipitate are obtained. The zinc-containing precipitate is sent to the smelting system.

[0035] (2) Oxidative leaching: The selenium-mercury slag after impurity removal was subjected to oxidative leaching. In the leaching system, the leaching liquid-solid ratio was 15 mL / g, the mass percentage of hydrogen peroxide was 4%, the mass percentage of hydrochloric acid was 3%, the leaching temperature was 30 °C, the leaching time was 1.5 h, and the leaching rate of selenium and mercury was 99%.

[0036] (3) Mercury precipitation: After leaching, the selenium-mercury solution was subjected to alkali precipitation, and the pH was maintained at about 12. 14.2 g of orange-yellow mercuric oxide precipitate was obtained. 100 g of dried acid mud contained 12.8 g of mercury, indicating that the mercuric oxide precipitate contained a small amount of impurities. The recovery rate of mercury was close to 100%; (4) Reduction precipitation of selenium: After mercury precipitation, solid-liquid separation is performed to obtain a selenium-containing solution, which is acidified to a pH of 0-1 and maintained at all times. Sodium sulfite is added to reduce and precipitate selenium. When the pH does not change significantly, the addition of sodium sulfite is stopped. The reduction time is 2 h and the reduction temperature is 80 °C. 42.98 g of gray selenium precipitate is obtained, and 100 g of dried acid mud contains 45.1 g of selenium. Therefore, the recovery rate of selenium is 95.3%; (5) Mixed neutralization: The acidic wastewater generated after the extraction of lead-containing waste liquid and selenium and mercury, and the alkaline wastewater generated in the impurity removal step are mixed and neutralized, and then the lead-containing precipitate and neutralized wastewater are obtained through solid-liquid separation. The lead-containing precipitate is sent to the smelting system. The wastewater mainly contains NaCl and Na 2 SO 4 , so it can be reused in the lead removal step.

[0037] Example 3 Example The lead-containing selenomercuric acid mud for resource utilization comes from the lead smelting system, and its water content is 27.2%. The main phases are HgSe and Se, and the composition content is shown in Table 3. In the experiment, 100 g of dried lead-containing selenomercuric acid mud was taken.

[0038]

[0039] (1) Impurity removal: Lead-containing selenium-mercury acid mud is removed by high-concentration sodium chloride solution. Sodium chloride solution can convert lead sulfate into soluble complexes of lead, while HgSe, Se and ZnS in the acid mud cannot be leached by sodium chloride. After solid-liquid separation, lead removal slag and lead-containing waste liquid are obtained. The main element composition of the lead removal slag is shown in Table 3. The concentration of sodium chloride solution is 250g / L, and the leaching temperature is 70℃. The leaching time is 1.5h, and the liquid-solid ratio is 10mL / g. Subsequently, dilute sulfuric acid is used to remove zinc from the lead removal slag and obtain selenium-mercury slag and zinc-containing waste liquid. The leaching conditions are: 4% sulfuric acid, liquid-solid ratio: 10mL / g, temperature: 40℃, and leaching time: 1h. NaOH is added to the zinc-containing waste liquid to make the pH between 9 and 12, and waste liquid and zinc-containing precipitate are obtained. The zinc-containing precipitate is sent to the smelting system.

[0040] (2) Oxidative leaching: The selenium-mercury slag after impurity removal was subjected to oxidative leaching. In the leaching system, the liquid-to-solid ratio was 15 mL / g, the mass percentage of hydrogen peroxide was 6%, the mass percentage of hydrochloric acid was 5%, the leaching temperature was 40 °C, the leaching time was 2 h, and the leaching rate of selenium and mercury was 99%.

[0041] (3) Mercury precipitation: After leaching, the selenium mercury solution was subjected to alkali precipitation, and the pH was maintained at about 12. 14.8 g of orange-yellow mercuric oxide precipitate was obtained, and 100 g of dried acid mud contained 13.5 g of mercury, indicating that the mercuric oxide precipitate contained a small amount of impurities. The recovery rate of mercury was close to 100%; (4) Reduction precipitation of selenium: After mercury precipitation, solid-liquid separation is performed to obtain a selenium-containing solution, which is acidified to a pH of 0-1 and maintained at all times. Sodium sulfite is added to reduce and precipitate selenium. When the pH does not change significantly, the addition of sodium sulfite is stopped. The reduction time is 2.5 h and the reduction temperature is 80 °C. 48.14 g of gray selenium precipitate is obtained, and 100 g of dried acid mud contains 50.1 g of selenium. Therefore, the recovery rate of selenium is 96.1%; (5) Mixed neutralization: The acidic wastewater generated after the extraction of lead-containing waste liquid and selenium and mercury, and the alkaline wastewater generated in the impurity removal step are mixed and neutralized, and then the lead-containing precipitate and neutralized wastewater are obtained through solid-liquid separation. The lead-containing precipitate is sent to the smelting system. The wastewater mainly contains NaCl and Na 2 SO 4 , so it can be reused in the lead removal step.

Claims

1. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud, characterized in that: The following steps are involved: 1) Leaching the mercury-containing selenomercuric acid mud with a sodium chloride solution to obtain lead-removing slag and lead-containing waste liquid; 2) Leaching the lead removal slag with dilute sulfuric acid to obtain zinc-containing waste liquid and selenium-mercury slag; 3) hydrolyzing and precipitating the zinc-containing waste liquid to obtain zinc-containing precipitate and alkaline waste liquid; 4) subjecting the selenium-mercury slag to oxidative acid leaching to obtain a selenium-mercury leaching solution; 5) neutralizing and precipitating the selenium-mercury leaching solution to obtain mercuric oxide precipitate and selenium-containing solution; 6) Acidifying and reducing the selenium-containing solution to obtain crude selenium precipitate and acidic waste liquid; 7) The lead-containing waste liquid, alkaline waste liquid and acidic waste liquid are mixed for neutralization and precipitation to obtain lead-containing precipitate.

2. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: The lead-selenomercuric acid mud mainly contains HgSe, PbSO4 and ZnS. The mass content of mercury is 10-20%, the mass content of selenium is 40-60%, the mass content of lead is 10-20% and the mass content of zinc is 0.5-2.0%.

3. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 1), the leaching conditions are: the concentration of the sodium chloride solution is 200-400 g / L, the liquid-solid ratio is 10-15 mL / g, the leaching temperature is 50-80° C., and the leaching time is 1-2 h.

4. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 2), the leaching conditions are: the mass percentage concentration of dilute sulfuric acid is 3-8%, the liquid-to-solid ratio is 10-20 mL / g, the leaching temperature is 25-60° C., and the leaching time is 0.5-1.0 h.

5. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 3), the conditions for hydrolysis precipitation are: using sodium hydroxide to adjust the pH to between 9 and 12.

6. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 4), the conditions for oxidative acid leaching are: using hydrogen peroxide as an oxidant and hydrochloric acid as a leaching agent, in the leaching system, the mass percentage concentration of hydrochloric acid is 2-5%, the mass percentage concentration of hydrogen peroxide is 3-5%, the leaching temperature is 25-30°C, and the leaching time is 1-2h.

7. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 5), the conditions for neutralizing the precipitation are: adjusting the pH to between 11 and 13 using sodium hydroxide.

8. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 6), The acidification conditions are: using dilute sulfuric acid to adjust the pH to between 0 and 2; The conditions for reduction precipitation are: sodium sulfite is used as the reducing agent, the amount of the reducing agent is measured so that the pH no longer increases during the reduction process, the reduction temperature is 60~90℃, and the reduction time is 1~3h.

9. A green and efficient method for resource utilization of lead-containing selenomercuric acid mud according to claim 1, characterized in that: In step 7), the pH of the neutralization precipitate of the lead-containing waste liquid, the alkaline waste liquid and the acidic waste liquid is controlled to be neutral.

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