Composite iron removal and copper control method for zinc sub-oxidation leaching system and system thereof

Abstract

The application discloses a kind of secondary zinc oxide leaching system composite iron removal and copper control method and system thereof, the system includes slurry tank, oxygen supply unit, pre-oxidation reaction tank, neutral leaching unit, acidic leaching unit;The method comprises: secondary zinc oxide desulfurization after slurry is pre-oxidized with oxygen;At lower temperature, longer residence time, lower stirring intensity, oxygen is introduced to carry out neutral leaching, and the leachate is sent to zinc smelting system to recover zinc;At higher temperature, shorter residence time, higher stirring intensity, oxygen is introduced to carry out acid leaching, and the leachate is returned to neutral leaching step for recycling.The application can reduce the copper content of lead concentrate to below 0.1% by pre-oxidation and stage differentiation process parameter design, and the Fe 2+ Concentration is reduced to below 1g / L, completely replaces hydrogen peroxide and manganese dioxide, realizes system closed circuit, has remarkable economic benefit and environmental benefit.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a composite method and system for iron removal and copper control in a zinc oxide leaching system. Background Technology

[0002] In the hydrometallurgical zinc refining process, some of the zinc oxide produced by the rotary kiln is returned to the zinc oxide acid leaching system after tail gas desulfurization. The main reaction in this zinc oxide desulfurization process is: ZnO + SO2 → ZnSO3. However, practice has shown that returning the desulfurized slurry containing a large amount of zinc sulfite to the leaching system causes a series of serious technical problems.

[0003] Analysis revealed that zinc sulfite possesses strong reducing properties. Under the acidic and high-temperature environment of the leaching system, it undergoes a reduction reaction with metal ions in the solution, reducing Fe in the solution. 3+ Reduced to Fe 2+ 2Fe 3+ + SO3 2- +H₂O=2Fe 2+ + SO4 2- +2H + This leads to a sharp increase in the concentration of ferrous ions in the leachate, with a peak value reaching 13 g / L; at the same time, it also causes the Cu in the solution to... 2+ Reduced to Cu + :2Cu 2+ +SO3 2- +H₂O=Cu + + SO4 2- + 2H + And Cu + It is extremely unstable and will rapidly form insoluble cuprous oxide (Cu2O) or cuprous sulfite (Cu2SO3) precipitates, causing serious copper loss.

[0004] To address the aforementioned problems, existing technologies generally employ the addition of large amounts of hydrogen peroxide and manganese dioxide to the leaching system, utilizing their oxidizing properties to oxidize Fe. 2+ Re-oxidized to Fe 3+ and Cu + Oxidized to Cu 2+ The main reactions include: 2H + +SO3 2- +MnO2=SO4 2- +H2O+Mn 2+ H2O2 + SO3 2- =H2O+SO4 2- 2H + +2Fe 2++H₂O₂=2H₂O+2Fe 3+ 4H + +Cu₂O + H₂O₂ = 2Cu 2+ +3H2O 4H + +2Fe 2+ +MnO2=2Fe 3+ +Mn 2+ +2H2O 6H + +MnO2+Cu2O=2Cu 2+ +Mn 2+ +3H2O However, this technical approach has the following significant problems: First, hydrogen peroxide is easily decomposed at high leaching temperatures (80-85℃) (2H₂O₂=2H₂O+O₂↑), resulting in low utilization and huge consumption (one company consumes 30 tons per day at a cost of 24,000 yuan / day); second, the addition of manganese dioxide introduces a large amount of Mn. 2+ This leads to a continuous increase in manganese ion concentration in the wet process, severely affecting the DC power consumption of the zinc electrowinning process and increasing the difficulty and frequency of cathode plate scraping. Furthermore, the aforementioned oxidants are not ideal in suppressing copper loss; the copper content in the secondary zinc oxide leaching residue (lead concentrate) remains as high as 0.82%~1.5%, resulting in a significant loss of valuable copper.

[0005] Therefore, it is necessary to develop a method that can fundamentally solve the Fe problem caused by the reducing properties of zinc sulfite. 2+ A composite method for iron removal and copper control that addresses interference and copper loss issues while simultaneously reducing oxidant costs, avoiding the introduction of impurity ions, and achieving clean production has significant industrial value. Summary of the Invention

[0006] In existing hydrometallurgical zinc refining processes, when the slurry after zinc oxide desulfurization is returned to the leaching system, the reducing properties of zinc sulfite lead to Fe... 2+ The large-scale generation and significant copper reduction losses, coupled with the high cost of using hydrogen peroxide and manganese dioxide, and the introduction of impurities such as Mn, all contribute to the problem. 2+ To address the current unsatisfactory results, the first objective of this invention is to provide a composite iron removal and copper control system for a zinc oxide leaching system, and a method for composite iron removal and copper control in a zinc oxide leaching system, which can remove Fe from the acid leaching filtrate. 2+ The concentration was reduced to below 1 g / L, and the copper content in the leaching residue (lead concentrate) was reduced to below 0.1%.

[0007] The first objective of this invention is achieved by the following technical solution: A composite iron removal and copper control system for a zinc oxide leaching system includes a slurry tank, an oxygen supply unit, a pre-oxidation reaction tank, a neutral leaching unit, an acidic leaching unit, and a lead concentrate storage tank. The outlet of the desulfurization slurry pipeline is connected to the inlet of the pulping tank; the outlet of the pulping tank is connected to the inlet of the pre-oxidation reaction tank; the outlet of the pre-oxidation reaction tank is connected to the inlet of the neutral leaching unit; the outlet of the intermediate leaching underflow of the neutral leaching unit is connected to the inlet of the acid leaching unit; the outlet of the lead concentrate of the acid leaching unit is connected to the inlet of the lead concentrate storage tank; and the outlet of the acid leaching filtrate of the acid leaching unit is connected to the inlet of the neutral leaching unit. The outlet of the oxygen supply unit is connected to the inlet of the pre-oxidation reaction tank, the neutral leaching unit, and the acidic leaching unit, respectively.

[0008] Furthermore, the pre-oxidation reaction tank includes a pre-oxidation tank body and a stirring device. The bottom of the pre-oxidation tank body has a conical structure and a discharge port for easy slurry discharge. The top of the pre-oxidation tank body is equipped with a sealed cover to prevent oxygen escape and slurry splashing. A feed inlet is provided on the upper side wall of the pre-oxidation tank body to receive the zinc oxide desulfurized slurry from the pulping tank. An air inlet is provided on the lower side wall of the pre-oxidation tank body. An oxygen distributor with a ring-shaped pipe structure is provided inside the pre-oxidation tank body at the air inlet. Several air holes are evenly opened on the pipe wall of the oxygen distributor to evenly disperse the introduced industrial oxygen in the slurry in the form of microbubbles, increasing the contact area of ​​the gas, liquid, and solid phases and improving the oxygen solubility and utilization rate. A tail gas discharge port is provided on the sealed cover plate, and a tail gas discharge pipe and a tail gas discharge valve are provided at the tail gas discharge port. The stirring device includes a stirring motor located on the top outer side of the pre-oxidation tank, a stirring shaft extending into the pre-oxidation tank, and a stirring impeller installed at the lower end of the stirring shaft; it stirs at a speed of 60-150 r / min to form an up-and-down circulating flow of the slurry, so that oxygen bubbles are fully mixed with the desulfurized slurry and the gas-liquid mass transfer is promoted.

[0009] Furthermore, the neutral leaching unit includes a multi-stage intermediate leaching tank and an intermediate leaching solid-liquid separation device arranged in series. The outlet of the last stage intermediate leaching tank is connected to the inlet of the intermediate leaching solid-liquid separation device. The outlet of the intermediate leaching solid-liquid separation device is the intermediate leaching underflow outlet, and the outlet of the intermediate leaching solid-liquid separation device is the intermediate leaching filtrate outlet. An air distributor is provided at the bottom of each stage of the intermediate immersion tank, and the outlet of the oxygen supply unit is connected to the inlet of the air distributor of each stage of the intermediate immersion tank; an agitator is provided in each stage of the intermediate immersion tank. The outlet of the intermediate immersion acid storage tank is connected to the first-stage intermediate immersion tank via a pipeline.

[0010] Furthermore, the acid leaching unit includes a multi-stage acid leaching tank and an acid leaching solid-liquid separation device arranged in series. The outlet of the last stage acid leaching tank is connected to the inlet of the acid leaching solid-liquid separation device. The outlet of the acid leaching solid-liquid separation device is the lead concentrate outlet, and the liquid outlet of the acid leaching solid-liquid separation device is the acid leaching filtrate outlet. An air distributor is provided at the bottom of each stage acid leaching tank, and the air outlet of the oxygen supply unit is connected to the inlet of the air distributor of each stage acid leaching tank. An agitator is provided in each stage acid leaching tank. The outlet of the acid leaching solution storage tank is connected to the first-stage acid leaching tank via a pipeline.

[0011] The second objective of this invention is achieved by the following technical solution: A method for removing iron and controlling copper using a composite iron removal and copper control system in a zinc oxide leaching system includes the following steps: S1. Pre-oxidation: The zinc slurry after desulfurization of zinc oxide is fed into the pre-oxidation reaction tank and mixed with industrial oxygen from the oxygen supply unit to carry out the pre-oxidation reaction, oxidizing the zinc sulfite in the slurry into zinc sulfate. S2, Neutral Leaching: The pre-oxidized slurry is fed into the neutral leaching unit. Zinc electrolytic waste liquid or sulfuric acid solution containing sulfuric acid is added through the intermediate leaching acid storage tank. Oxygen is introduced under continuous stirring to carry out neutral leaching, removing Fe from the solution. 2+ Oxidized to Fe 3+ The corresponding reaction formula is: 4Fe 2+ +O2+4H + =4Fe 3+ +2H2O Simultaneously, zinc is introduced into the solution in the form of zinc sulfate until the pH value is between 4.8 and 5.2, at which point the reaction is complete. After solid-liquid separation, zinc-containing intermediate leaching filtrate and intermediate leaching bottom stream are obtained. S3. Acid Leaching: The intermediate leaching solution is introduced into the acid leaching unit. Concentrated sulfuric acid is added through the acid leaching solution storage tank, and oxygen is introduced under continuous stirring to leach the Cu2O and Cu2SO3 in the residue, oxidizing and dissolving them into Cu. 2+ The reaction continues until the acidity reaches 40-50 g / L, at which point the reaction is complete. After solid-liquid separation, the acid leaching filtrate and low copper-lead concentrate are obtained. S4. Filtrate Reuse: The zinc-containing intermediate leaching filtrate is sent to the purification process of the zinc smelting system to recover zinc; the acid leaching filtrate is returned to the neutral leaching unit for recycling.

[0012] Furthermore, step S1, the pre-oxidation step, is carried out at room temperature, with an oxygen flow rate of 60-100 mg / L. 3 / h, with a stay time of 0.3-0.8h.

[0013] Furthermore, in step S2, the neutral leaching step, the temperature is 80-85℃, the time is 1.5-2.5h, the stirring speed is 250-350r / min, and the oxygen introduction rate is 40-130m³. 3 / h / slot.

[0014] Furthermore, in step S3, the acid leaching step, the temperature is 87-92℃, the time is 2.5-3.5h, the stirring speed is 350-450r / min, and the oxygen introduction rate is 40-130m³. 3 / h / slot. Advantages of this invention: This invention completely eliminates the reducing properties of zinc sulfite through pre-oxidation, combined with a staged differentiated oxygen oxidation process involving low-temperature, long-duration, low-stirring mid-immersion and high-temperature, short-duration, strong-stirring acid immersion. This process can remove Fe from the acid immersion filtrate. 2+ The concentration was reduced from 8 g / L in the original process to below 1 g / L, a reduction of >87%; the copper content in lead concentrate was reduced from 1.64% to below 0.1%, a reduction of >94%, significantly improving the copper recovery rate and reducing copper losses by approximately 10 million yuan per year. The pre-oxidation step effectively decomposed zinc sulfite, reducing the on-site SO2 concentration from >50 ppm to <1 ppm, improving the operating environment; the acid leaching filtrate was returned to the intermediate leaching for recycling, forming a closed-loop cycle and achieving comprehensive resource utilization. By using inexpensive industrial oxygen to completely replace hydrogen peroxide and manganese dioxide, the problem of huge consumption caused by the high-temperature decomposition of hydrogen peroxide was avoided, while the introduction of Mn by manganese dioxide was solved. 2+ The industry challenge of pollution systems makes the system Mn 2+ The concentration is stabilized at 3-6 g / L, and it is estimated that the cost of oxidant will be reduced by approximately 8 million yuan per year. This invention operates under normal pressure conditions, and the equipment investment and operating costs are far lower than those of oxygen pressure acid leaching technology, making it suitable for large-scale industrial applications. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the system connection in Example 1.

[0016] In the diagram: 1. Desulfurized slurry pipeline; 2. Slurry tank; 3. Oxygen supply unit; 4. Pre-oxidation reaction tank; 41. Pre-oxidation tank body; 42. Stirring device; 43. Tail gas discharge pipe; 44. Tail gas discharge valve; 5. Neutral leaching unit; 51. Intermediate leaching tank; 52. Intermediate leaching solid-liquid separation device; 53. Intermediate leaching acid storage tank; 6. Acid leaching unit; 61. Acid leaching tank; 62. Intermediate leaching solid-liquid separation device; 63. Intermediate leaching acid storage tank; 7. Lead concentrate storage tank. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 like Figure 1 The composite iron removal and copper control system of the zinc oxide leaching system shown includes a pulping tank 2, an oxygen supply unit 3, a pre-oxidation reaction tank 4, a neutral leaching unit 5, an acidic leaching unit 6, and a lead concentrate storage tank 7. The pre-oxidation reaction tank 4 includes a pre-oxidation tank body 41 and a stirring device 42. The bottom of the pre-oxidation tank body 41 is conical and has a discharge port. The top of the pre-oxidation tank body 41 is equipped with a sealed cover plate. A feed port is opened on the upper side wall of the pre-oxidation tank body 41. An air inlet is opened on the lower side wall of the pre-oxidation tank body 41. An oxygen distributor with an annular pipe structure is provided inside the pre-oxidation tank body 41 at the air inlet. Several air holes are evenly opened on the pipe wall of the oxygen distributor. A tail gas discharge port is opened on the sealed cover plate. A tail gas discharge pipe 43 and a tail gas discharge valve 44 are provided at the tail gas discharge port. The stirring device 42 includes a stirring motor located on the top outside of the pre-oxidation tank body 41, a stirring shaft extending into the pre-oxidation tank body 41, and a stirring impeller installed at the lower end of the stirring shaft.

[0019] The neutral leaching unit 5 includes three intermediate leaching tanks 51 arranged in series and an intermediate leaching solid-liquid separation device 52. The outlet of the last intermediate leaching tank 51 is connected to the inlet of the intermediate leaching solid-liquid separation device 52. The outlet of the intermediate leaching solid-liquid separation device 52 is the intermediate leaching underflow outlet, and the outlet of the intermediate leaching solid-liquid separation device 52 is the intermediate leaching filtrate outlet. An air distributor is provided at the bottom of each intermediate leaching tank 51, and the outlet of the oxygen supply unit 3 is connected to the inlet of the air distributor of each intermediate leaching tank 51. An agitator is provided in each intermediate leaching tank 51. The outlet of the intermediate leaching acid storage tank 53 is connected to the first intermediate leaching tank 51 through a pipeline.

[0020] The acid leaching unit 6 includes three acid leaching tanks 61 arranged in series and an acid leaching solid-liquid separation device 62. The outlet of the last acid leaching tank 61 is connected to the inlet of the acid leaching solid-liquid separation device 62. The outlet of the acid leaching solid-liquid separation device 62 is the lead concentrate outlet, and the liquid outlet of the acid leaching solid-liquid separation device 62 is the acid leaching filtrate outlet. An air distributor is provided at the bottom of each acid leaching tank 61, and the air outlet of the oxygen supply unit 3 is connected to the air distributor inlet of each acid leaching tank 61. An agitator is provided in each acid leaching tank 61. The liquid outlet of the acid leaching acid storage tank 63 is connected to the first acid leaching tank 61 through a pipeline.

[0021] The outlet of the desulfurization slurry pipeline 1 is connected to the inlet of the pulping tank 2. The outlet of the pulping tank 2 is connected to the inlet of the pre-oxidation reaction tank 4. The outlet of the pre-oxidation reaction tank 4 is connected to the inlet of the first-stage intermediate leaching tank 51 of the neutral leaching unit 5. The outlet of the intermediate leaching underflow of the neutral leaching unit 5 is connected to the inlet of the first-stage acid leaching tank 61 of the acid leaching unit 6. The outlet of the lead concentrate of the acid leaching unit 6 is connected to the inlet of the lead concentrate storage tank 7. The outlet of the acid leaching filtrate of the acid leaching unit 6 is connected to the inlet of the first-stage intermediate leaching tank 51. The outlet of the oxygen supply unit 3 is connected to the inlet of the pre-oxidation reaction tank 4, the intermediate immersion tank 51 of each stage, and the acid immersion tank 61 of each stage.

[0022] In this embodiment, both the intermediate immersion solid-liquid separation device 52 and the acid immersion solid-liquid separation device 62 are plate and frame filter presses, and the inner wall of the pre-oxidation tank 41 is provided with an anti-corrosion coating; the gas distributors installed in the intermediate immersion tank 51 and the acid immersion tank 61 have the same structure as the oxygen distributors installed inside the pre-oxidation tank 41.

[0023] Example 2 A method for removing iron and controlling copper using a composite iron removal and copper control system in a zinc oxide leaching system includes the following steps: S1. Pre-oxidation: In the hydrometallurgical zinc slurry system of Bayannur Zijin Nonferrous Metals Co., Ltd., a zinc oxide slurry with a solid content of 30% and a zinc sulfite content of approximately 15 g / L, after desulfurization, is fed into a pre-oxidation reaction tank. At room temperature, it is mixed with industrial oxygen from the oxygen supply unit to undergo a pre-oxidation reaction, oxidizing the zinc sulfite in the slurry into zinc sulfate. The oxygen feed rate is 80 m³ / L. 3 / h, with a stay time of 0.5h; S2, Neutral Leaching: The pre-oxidized slurry is passed into the neutral leaching unit. Sulfuric acid solution is added through the intermediate leaching acid storage tank at 83°C, and the mixture is continuously stirred at 300 r / min with a stirring speed of 90 m. 3 / h / Oxygen is introduced into the tank for neutral leaching to remove Fe from the solution. 2+ Oxidized to Fe 3+ Simultaneously, zinc enters the solution in the form of zinc sulfate. After 2.0 hours of reaction, the pH value is 5.1, and the reaction is complete. After solid-liquid separation, zinc-containing intermediate leaching filtrate and intermediate leaching bottom stream are obtained. S3, Acid Leaching: The intermediate leaching solution is introduced into the acid leaching unit. Concentrated sulfuric acid is added through the acid leaching solution storage tank at 90°C, and the mixture is continuously stirred at 400 r / min with a stirring speed of 80 m... 3 The oxygen flow rate in the / h / tank is increased to facilitate acid leaching, oxidizing and dissolving the Cu2O and Cu2SO3 in the slag into Cu. 2+After 3.0 hours, the acidity reached 45 g / L, and the reaction was completed. After solid-liquid separation, acid leaching filtrate and low copper-lead concentrate were obtained. S4. Filtrate Reuse: The zinc-containing intermediate leaching filtrate is sent to the purification process of the zinc smelting system to recover zinc; the acid leaching filtrate is returned to the neutral leaching unit for recycling.

[0024] Fe in the intermediate filtrate obtained after treatment using the method of this embodiment 2+ The Fe concentration in the acid leaching filtrate was 4.2 g / L. 2+ The concentration was 0.6 g / L; the lead concentrate contained 0.063% copper and 3.6% zinc; the system Mn 2+ The concentration was 4.8 g / L; the on-site SO2 concentration was <1 ppm.

[0025] In this embodiment, the temperatures in steps S2, neutral leaching, and S3, acid leaching are controlled by heating jackets installed on the outer walls of the intermediate leaching tank and the acid leaching tank.

[0026] Example 3 The only difference between this embodiment and Embodiment 2 is that: S1, Pre-oxidation: Oxygen flow rate 60m³ 3 / h, stay time 0.3h; S2, Neutral Leaching: Temperature 80℃, residence time 1.5h, stirring speed 250r / min, oxygen flow rate 40m³ / min. 3 / h / tank, final pH=5.2.

[0027] S3, Acid Leaching: Temperature 87℃, Residence Time 2.5h, Stirring Speed ​​350r / min, Oxygen Injection Rate 40m³ / min 3 / h / tank, the final acidity is 40g / L.

[0028] The results showed that the Fe in the intermediate filtrate obtained in this embodiment was high. 2+ The Fe concentration in the acid leaching filtrate was 5.8 g / L. 2+ The concentration was 0.9 g / L; the lead concentrate contained 0.085% copper and 3.7% zinc; the system Mn 2+ The concentration was 5.2 g / L; the on-site SO2 concentration was 2-5 ppm (occasionally trace amounts).

[0029] Example 4 The only difference between this embodiment and Embodiment 2 is that: S1, Pre-oxidation: Oxygen flow rate 100m³ 3 / h, stay time 0.8h; S2, Neutral Leaching: Temperature 85℃, residence time 2.5h, stirring speed 350r / min, oxygen flow rate 130m³ / min. 3 / h / tank, endpoint pH=5.0.

[0030] S3, Acid Leaching: Temperature 92℃, Residence Time 3.5h, Stirring Speed ​​450r / min, Oxygen Injection Rate 130m³ 3 / h / tank, final acidity 30g / L.

[0031] The results showed that the Fe in the intermediate filtrate obtained in this embodiment was high. 2+ The Fe concentration in the acid leaching filtrate was 3.5 g / L. 2+ The concentration was 0.4 g / L; the lead concentrate contained 0.050% copper and 3.5% zinc; the system Mn 2+ The concentration was 4.2 g / L; the on-site SO2 concentration was 0 ppm.

[0032] Comparative Example 1 This comparative example uses the same raw materials and basic process as Example 1, but does not introduce oxygen or perform pre-oxidation. Instead, it adds oxidants according to the original production formula: hydrogen peroxide (total usage 30t / d, equivalent to about 1.25t / h) is added to the intermediate immersion tank, and manganese dioxide (total usage 6t / d, equivalent to 0.25t / h) is added to the acid immersion tank.

[0033] The specific differences from Example 1 are as follows: (1) No pre-oxidation reactor or pre-oxidation step; (2) No oxygen supply unit and no oxygen supply; (3) Use chemical oxidants (hydrogen peroxide, manganese dioxide) instead of oxygen; (4) The acid leaching filtrate is discharged externally and not returned to the intermediate leaching system.

[0034] The remaining parameters (temperature, time, stirring) were the same as those for the intermediate soaking (83°C, 2h, 300r / min) and acid soaking (90°C, 3h, 400r / min) in Example 1.

[0035] After treatment, Fe in the intermediate filtrate 2+ The Fe concentration in the acid leaching filtrate was 11 g / L. 2+ The concentration was 8 g / L; the lead concentrate contained 1.64% copper and 3.9% zinc; the system Mn 2+ The concentration continued to rise to over 10 g / L; the on-site SO2 concentration was >50 ppm (off the charts).

[0036] Comparative Example 2 This comparative example uses the same raw materials and oxygen as in Example 1, but does not employ phased differentiated process control. The specific differences are as follows: (1) No pre-oxidation step; (2) The same process parameters were used for both intermediate leaching and acid leaching (temperature 85℃, residence time 2.5h, stirring speed 350r / min), and the oxygen flow rate was set to 85m³ / min. 3 / h / slot; (3) The temperature, time and stirring of the intermediate immersion and acid immersion were not differentiated.

[0037] After treatment, Fe in the intermediate filtrate 2+ The Fe concentration in the acid leaching filtrate is 7 g / L. 2+ The concentration was 4 g / L; the lead concentrate contained 0.42% copper and 3.7% zinc; the system Mn 2+ The concentration was 5 g / L; the on-site SO2 concentration was 8 ppm.

[0038] Comparative Example 3 The specific differences between this comparative example and Example 1 are as follows: (1) Neutral leaching is the same as in Example 1 (83°C, 2h), but without the pre-oxidation step; (2) Change acid leaching to oxygen pressure acid leaching: Add the bottom stream of the intermediate leaching to the high pressure reactor, add sulfuric acid to make the initial acid concentration 140g / L, introduce industrial oxygen, control the oxygen pressure to 0.6MPa, the temperature to 140℃, and the residence time to 2h; (3) High-pressure equipment (high-pressure reactor) and high-pressure steam heating are required; (4) The acid leaching filtrate is not returned to the intermediate leaching system.

[0039] After treatment, Fe in the intermediate filtrate 2+ The Fe concentration in the acid leaching filtrate was 9 g / L. 2+ The concentration was 3 g / L; the lead concentrate contained 0.28% copper and 3.8% zinc; the system Mn 2+ The concentration was 4.2 g / L; the on-site SO2 concentration was <1 ppm.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite iron removal and copper control system for a zinc oxide leaching system, characterized in that, It includes a pulping tank, an oxygen supply unit, a pre-oxidation reaction tank, a neutral leaching unit, an acidic leaching unit, and a lead concentrate storage tank; The outlet of the desulfurization slurry pipeline is connected to the inlet of the pulping tank; the outlet of the pulping tank is connected to the inlet of the pre-oxidation reaction tank; the outlet of the pre-oxidation reaction tank is connected to the inlet of the neutral leaching unit; the outlet of the intermediate leaching underflow of the neutral leaching unit is connected to the inlet of the acid leaching unit; the outlet of the lead concentrate of the acid leaching unit is connected to the inlet of the lead concentrate storage tank; and the outlet of the acid leaching filtrate of the acid leaching unit is connected to the inlet of the neutral leaching unit. The outlet of the oxygen supply unit is connected to the inlet of the pre-oxidation reaction tank, the neutral leaching unit, and the acidic leaching unit, respectively.

2. The composite iron removal and copper control system of the zinc oxide leaching system according to claim 1, characterized in that, The pre-oxidation reaction tank includes a pre-oxidation tank body and a stirring device. The bottom of the pre-oxidation tank body is conical and has a discharge port. The top of the pre-oxidation tank body is equipped with a sealed cover plate. A feed port is opened on the upper side wall of the pre-oxidation tank body. An air inlet is opened on the lower side wall of the pre-oxidation tank body. An oxygen distributor with an annular pipe structure is provided inside the pre-oxidation tank body at the air inlet. Several air holes are evenly opened on the pipe wall of the oxygen distributor. A tail gas discharge port is opened on the sealed cover plate. A tail gas discharge pipe and a tail gas discharge valve are provided at the tail gas discharge port. The stirring device includes a stirring motor located on the top outside of the pre-oxidation tank, a stirring shaft extending into the interior of the pre-oxidation tank, and a stirring impeller installed at the lower end of the stirring shaft.

3. The composite iron removal and copper control system of the zinc oxide leaching system according to claim 1, characterized in that, The neutral leaching unit includes a series of intermediate leaching tanks and an intermediate leaching solid-liquid separation device. The outlet of the last intermediate leaching tank is connected to the inlet of the intermediate leaching solid-liquid separation device. The outlet of the intermediate leaching solid-liquid separation device is the intermediate leaching underflow outlet, and the outlet of the intermediate leaching solid-liquid separation device is the intermediate leaching filtrate outlet. An air distributor is provided at the bottom of each stage of the intermediate immersion tank, and the outlet of the oxygen supply unit is connected to the inlet of the air distributor of each stage of the intermediate immersion tank; an agitator is provided in each stage of the intermediate immersion tank. The outlet of the intermediate immersion acid storage tank is connected to the first-stage intermediate immersion tank via a pipeline.

4. The composite iron removal and copper control system of the zinc oxide leaching system according to claim 1, characterized in that, The acid leaching unit includes a multi-stage acid leaching tank and an acid leaching solid-liquid separation device arranged in series. The outlet of the last stage acid leaching tank is connected to the inlet of the acid leaching solid-liquid separation device. The outlet of the acid leaching solid-liquid separation device is the lead concentrate outlet, and the liquid outlet of the acid leaching solid-liquid separation device is the acid leaching filtrate outlet. An air distributor is provided at the bottom of each stage acid leaching tank, and the air outlet of the oxygen supply unit is connected to the inlet of the air distributor of each stage acid leaching tank. An agitator is provided in each stage acid leaching tank. The outlet of the acid leaching solution storage tank is connected to the first-stage acid leaching tank via a pipeline.

5. A method for removing iron and controlling copper using a composite iron removal and copper control system of a zinc oxide leaching system according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Pre-oxidation: The zinc slurry after desulfurization of zinc oxide is fed into the pre-oxidation reaction tank and mixed with industrial oxygen from the oxygen supply unit to carry out the pre-oxidation reaction, oxidizing the zinc sulfite in the slurry into zinc sulfate. S2, Neutral Leaching: The pre-oxidized slurry is fed into the neutral leaching unit. Sulfuric acid solution is added through the intermediate leaching acid storage tank. Oxygen is introduced under continuous stirring to carry out neutral leaching, removing Fe from the solution. 2+ Oxidized to Fe 3+ Simultaneously, zinc is introduced into the solution in the form of zinc sulfate until the pH value is between 4.8 and 5.2, at which point the reaction is complete. After solid-liquid separation, zinc-containing intermediate leaching filtrate and intermediate leaching bottom stream are obtained. S3. Acid Leaching: The intermediate leaching solution is introduced into the acid leaching unit. Concentrated sulfuric acid is added through the acid leaching solution storage tank, and oxygen is introduced under continuous stirring to leach the Cu2O and Cu2SO3 in the residue, oxidizing and dissolving them into Cu. 2+ The reaction continues until the acidity reaches 40-50 g / L, at which point the reaction is complete. After solid-liquid separation, the acid leaching filtrate and low copper-lead concentrate are obtained. S4. Filtrate Reuse: The zinc-containing intermediate leaching filtrate is sent to the purification process of the zinc smelting system to recover zinc; the acid leaching filtrate is returned to the neutral leaching unit for recycling.

6. The composite iron removal and copper control method of a secondary zinc oxide leaching system according to claim 5, characterized in that, In step S1, the oxygen flow rate is 60-100 mg / L. 3 / h, with a stay time of 0.3-0.8h.

7. The composite iron removal and copper control method of a secondary zinc oxide leaching system according to claim 5, characterized in that, The S2 neutral leaching step is performed at a temperature of 80-85℃ for 1.5-2.5 hours, with a stirring speed of 250-350 r / min and an oxygen flow rate of 40-130 m³ / min. 3 / h / slot.

8. The composite iron removal and copper control method of a secondary zinc oxide leaching system according to claim 5, characterized in that, The S3 acid leaching step is performed at a temperature of 87-92℃ for 2.5-3.5 hours, with a stirring speed of 350-450 r / min and an oxygen flow rate of 40-130 m³ / min. 3 / h / slot.

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