Method for reducing lead content in zinc hydrometallurgy electrolytic zinc

Abstract

According to the method for reducing the lead content of the zinc hydrometallurgy electrolytic zinc, when an electrolytic bath is used for electrolytic deposition of zinc, the method comprises the following steps that (1) a lead-silver anode plate is arranged in an anode plate protection groove, and the lead-silver anode plate and a cathode aluminum plate are arranged in the electrolytic bath together; the connecting line direction of the filter cloth in each anode plate protection groove is perpendicular to the flowing direction of the electrolyte; (2) adding the purified zinc sulfate solution into the electrodeposition waste liquid, adding from one end of an electrolytic bath, and flowing out from the other end of the electrolytic bath; (3) introducing direct current; (4) after a single electrodeposition period is finished, taking out the cathode plate, stripping the zinc sheet, brushing the cathode aluminum plate to be smooth, and reloading the cathode aluminum plate into the electrolytic cell after the cathode aluminum plate is clean; and the anode and the anode plate protection groove are taken out every 10-30 days, and anode mud is cleaned. According to the method, insoluble lead-containing anode mud is physically isolated from entering a cathode region, and meanwhile, the arrangement of a filter cloth connecting line is controlled to be perpendicular to the flowing direction of electrolyte, so that the problem that the lead content of a zinc sheet is relatively high due to the fact that the anode mud enters the cathode region can be effectively solved.

Description

Technical Field

[0001] The invention relates to a method for reducing the lead content of electrolytic zinc in hydrometallurgical zinc smelting, belonging to the technical field of hydrometallurgical zinc smelting. Technical Background

[0002] In the field of hydrometallurgy, the main method of producing electrolytic zinc is to use lead-silver alloy anode, pure aluminum plate cathode, and direct current to electrolytically deposit zinc from sulfuric acid and zinc sulfate solution.

[0003] In this method, the lead-silver alloy anode will be corroded by sulfuric acid solution during the electrowinning process to generate PbSO4, which is then oxidized to generate PbO2, which reacts with Mn in the solution. 2+ Oxidized or Mn 2+ With Mn 7+ The MnO2 generated by the neutralization reaction forms anode mud, which eventually adheres to the anode or suspends in the electrolyte or settles to the bottom of the electrolytic cell, and is eventually removed by cleaning the cell and the anode plate. When electrolytic zinc is deposited, the lead is carried into the zinc sheet by the anode mud, which is the main reason for the high lead content in the electrolytic zinc, thereby affecting the quality of the electrolytic zinc and reducing the economic benefits of the enterprise. Summary of the invention

[0004] In view of the problem that lead-containing anode mud is carried into cathode zinc, resulting in high lead content in electrolytic zinc, the present invention proposes a method for reducing the lead content in electrolytic zinc during hydrometallurgy, by physically isolating insoluble lead-containing anode mud from entering the cathode area and controlling the arrangement of the filter cloth connection line to be perpendicular to the flow direction of the electrolyte, thereby effectively solving the problem that anode mud enters the cathode area, resulting in high lead content in zinc flakes.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for reducing the lead content of electrolytic zinc in hydrometallurgical zinc smelting, when electrolytic zinc deposition is performed in an electrolytic cell, comprising the following steps:

[0007] (1) Loading the lead-silver anode plate into an anode plate protection tank, and loading it into an electrolytic cell together with the cathode aluminum plate; the anode plate protection tank is formed by a bottom wall and surrounding walls on four sides, and has a hollow accommodating cavity, and the top is open, and a gap of 300-500 mm is left between the bottom wall of the anode plate protection tank and the bottom end of the anode plate; one set of opposite surrounding walls is composed of filter cloth, and the other set of opposite surrounding walls and the bottom wall are composed of a plate material that cannot leak;

[0008] The connection direction of the filter cloth in a single anode plate protection slot is perpendicular to the flow direction of the electrolyte;

[0009] (2) adding the purified zinc sulfate solution into the electrolytic waste liquid and adding it from one end of the electrolytic cell and letting it flow out from the other end; (3) passing direct current;

[0010] (4) After a single electrolytic cycle, remove the cathode plate, peel off the zinc sheet, brush the cathode aluminum plate until it is smooth and clean, and then reinstall it into the electrolytic cell; remove the anode and anode filter frame every 10-30 days to clean the anode mud.

[0011] Furthermore, the inter-pole spacing in step (1) is 90-150 mm.

[0012] Furthermore, in step (2), the purified zinc sulfate solution is added to the electrolytic waste liquid in a volume ratio of 1:8-20.

[0013] Furthermore, in step (3), direct current is introduced, and the cathode current density is controlled at 300-600 A / m 2 , the solution temperature is controlled at 35-42℃, and the electrodeposition time is controlled at 24-48h.

[0014] Beneficial effects of the present invention:

[0015] In the present application, when an electrolytic cell is used for electrolytic zinc deposition, on the one hand, the anode mud generated by the anode is physically isolated by specially providing an anode plate protection groove with a filter cloth, and on the other hand, the arrangement of the filter cloth connection line is arranged perpendicular to the flow direction of the electrolyte, thereby effectively solving the problem of anode mud entering the cathode area and causing high lead content in the zinc sheet. DETAILED DESCRIPTION

[0016] Example 1

[0017] In a hydrometallurgical zinc smelting plant, when electrolytically depositing zinc using an electrolytic cell, the lead-silver alloy anode plate is loaded into the anode plate protection tank and loaded into the electrolytic cell together with the cathode aluminum plate, with the same inter-electrode spacing of 120 mm;

[0018] The anode plate protection tank is formed by a bottom wall and surrounding walls on four sides, and has a hollow accommodating cavity with an open top. A gap of 400 mm is left between the bottom wall of the anode plate protection tank and the bottom end of the anode plate to collect anode mud; one set of opposite surrounding walls is composed of filter cloth, and the other set of opposite surrounding walls and the bottom wall are composed of plates that cannot leak;

[0019] The connection direction of the filter cloth in a single anode plate protection slot is perpendicular to the flow direction of the electrolyte;

[0020] Take out the anode and anode filter frame and clean the anode mud every 20 days.

[0021] The purified zinc sulfate solution was added to the electrolytic wastewater at a volume ratio of 1:15, and the solution was added to the electrolytic cell from one end and flowed out from the other end. Direct current was passed, and the cathode current density was controlled at 450A / m 2, the solution temperature is controlled at 38℃, and the electrowinning time is controlled at 36h. After a single cycle of electrowinning is completed, the cathode plate is removed, the zinc sheet is peeled off, the cathode aluminum plate is brushed smooth and clean, and then reloaded into the electrowinning tank. The zinc sheet produced contains 0.0008% lead, which meets the requirement of 99.995 zinc quality standard that lead is less than 0.0025%.

[0022] Example 2

[0023] In a hydrometallurgical zinc smelting plant, when using an electrolytic cell for electrolytic deposition of zinc, the lead-silver anode plate is loaded into the anode plate protection tank and loaded into the electrolytic cell together with the cathode aluminum plate, with the same inter-electrode spacing of 90 mm;

[0024] The anode plate protection tank is formed by a bottom wall and surrounding walls on four sides, and has a hollow accommodating cavity with an open top. A gap of 300 mm is left between the bottom wall of the anode plate protection tank and the bottom end of the anode plate; one set of opposite surrounding walls is formed by filter cloth, and the other set of opposite surrounding walls and the bottom wall are formed by a plate material that cannot leak;

[0025] The connection direction of the filter cloth in a single anode plate protection slot is perpendicular to the flow direction of the electrolyte;

[0026] Take out the anode and anode filter frame and clean the anode mud every 30 days;

[0027] The purified zinc sulfate solution was added to the electrolytic wastewater in a volume ratio of 1:8, and the solution was added to the electrolytic cell from one end and flowed out from the other end. Direct current was passed, and the cathode current density was controlled at 300A / m 2 , the solution temperature is controlled at 35℃, and the electrowinning time is controlled at 24h. Take out the cathode plate, peel off the zinc sheet, brush the cathode aluminum plate until it is smooth and clean, and then reload it into the electrowinning tank. The zinc sheet produced contains 0.0007% lead, which meets the requirement of 99.995 zinc quality standard that lead is less than 0.0025%.

[0028] Example 3

[0029] In a hydrometallurgical zinc smelting plant, when using an electrolytic cell for electrolytic zinc deposition, the lead-silver anode plate is loaded into the anode plate protection tank and loaded into the electrolytic cell together with the cathode aluminum plate, with the same inter-electrode spacing of 150mm;

[0030] The anode plate protection tank is formed by a bottom wall and surrounding walls on four sides, and has a hollow accommodating cavity with an open top. A gap of 500 mm is left between the bottom wall of the anode plate protection tank and the bottom end of the anode plate to collect anode mud; one set of opposite surrounding walls is composed of filter cloth, and the other set of opposite surrounding walls and the bottom wall are composed of plates that cannot leak;

[0031] Take out the anode and anode filter frame every 10 days to clean the anode mud;

[0032] The purified zinc sulfate solution was added to the electrolytic wastewater at a volume ratio of 1:20, and the solution was added to the electrolytic cell from one end and flowed out from the other end. Direct current was passed, and the cathode current density was controlled at 600A / m 2 , the solution temperature is controlled at 42℃, and the electrowinning time is controlled at 48h. Take out the cathode plate, peel off the zinc sheet, brush the cathode aluminum plate until it is smooth and clean, and then reload it into the electrowinning tank. The zinc sheet produced contains 0.0010% lead, which meets the requirement of 99.995 zinc quality standard that lead is less than 0.0025%.

[0033] Comparative Example 1

[0034] Except that no anode plate protection groove is provided, and then the lead-silver alloy anode plate and the cathode aluminum plate are loaded into the electrolytic cell together in a conventional manner, the rest is the same as Example 1.

[0035] The zinc flakes produced contain 0.0015% lead, which, although meeting the 99.995 zinc quality standard requirement of less than 0.0025% lead, is much higher than the 0.0007-0.001% lead content of the zinc flakes produced by this method.

[0036] Comparative Example 2

[0037] Except that no anode plate protection groove is provided and then the lead-silver alloy anode plate and the cathode aluminum plate are loaded into the electrolytic cell together in a conventional manner, the rest is the same as in Example 2.

[0038] The zinc flakes produced contain 0.0020% lead, which meets the requirement of 99.995 zinc quality standard for lead content less than 0.0025%, but is much higher than the lead content of 0.0007-0.001% of the zinc flakes produced by this method.

[0039] Comparative Example 3

[0040] Except that no anode plate protection groove is provided and the lead-silver alloy anode plate and the cathode aluminum plate are then loaded into the electrolytic cell together in a conventional manner, the rest is the same as in Example 3.

[0041] The zinc flakes produced contain 0.0014% lead, which, although meeting the 99.995 zinc quality standard requirement of less than 0.0025% lead, is much higher than the 0.0007-0.001% lead content of the zinc flakes produced by this method.

[0042] Comparative Example 4

[0043] Except that the connection direction of the filter cloth in a single anode plate protection slot is parallel to the flow direction of the electrolyte, the rest is the same as Example 1.

[0044] The zinc flakes produced contain 0.0022% lead, which meets the requirement of 99.995 zinc quality standard for lead content below 0.0025%, but is much higher than the lead content of 0.0007-0.001% of the zinc flakes produced by this method.

Claims

1. A method for reducing the lead content of electrolytic zinc in hydrometallurgical zinc smelting, characterized in that: When electrolytic zinc deposition is performed using an electrolytic cell, the following steps are included: (1) Loading the lead-silver anode plate into an anode plate protection tank, and loading it into an electrolytic cell together with the cathode aluminum plate; the anode plate protection tank is formed by a bottom wall and surrounding walls on four sides, and has a hollow accommodating cavity, and the top is open, and a gap of 300-500 mm is left between the bottom wall of the anode plate protection tank and the bottom end of the anode plate; one set of opposite surrounding walls is composed of filter cloth, and the other set of opposite surrounding walls and the bottom wall are composed of a plate material that cannot leak; The connection direction of the filter cloth in a single anode plate protection slot is perpendicular to the flow direction of the electrolyte; (2) adding the purified zinc sulfate solution into the electrolytic waste liquid and adding it from one end of the electrolytic cell and flowing out from the other end; (3) Applying direct current; (4) After a single electrolytic cycle, remove the cathode plate, peel off the zinc sheet, brush the cathode aluminum plate until it is smooth and clean, and then reinstall it into the electrolytic cell; remove the anode and anode plate protection tank every 10-30 days to clean the anode mud.

2. A method for reducing the lead content of electrolytic zinc in hydrometallurgical zinc smelting according to claim 1, characterized in that: The spacing between the same poles in step (1) is 90-150 mm.

3. A method for reducing the lead content of electrolytic zinc in hydrometallurgical zinc smelting according to claim 1, characterized in that: Step (2) The purified zinc sulfate solution is added to the electrolytic waste liquid in a volume ratio of 1:8-20.

4. A method for reducing lead content in electrolytic zinc produced by hydrometallurgy according to claim 1, characterized in that: In step (3), direct current is introduced, and the cathode current density is controlled at 300-600A / m 2 , the solution temperature is controlled at 35-42℃, and the electrodeposition time is controlled at 24-48h.