A method for recycling aluminum powder slag from zinc smelting cathode aluminum plate brushing

Abstract

The present invention belongs to the technical field of nonferrous metallurgy process, and specifically relates to a recycling method for zinc smelting cathode aluminum plate brush plate aluminum powder slag, comprising the following steps: adding zinc smelting cathode aluminum plate brush plate aluminum powder slag to zinc electrolysis waste liquid to form a mixed solution; adding the mixed solution to the zinc smelting neutral leaching process for neutral leaching; as the pH value increases during the neutral leaching process, a complex precipitate is formed, and acid leaching is performed along the intermediate leaching bottom flow; during the flotation process, heavy calcium powder is added to the acid leaching bottom flow to adjust the pH value, the acid leaching slag is placed in a multi-hearth furnace, oxygen and coke particles are introduced, and the fluorine-containing complex is removed by pyrolysis roasting. The present invention not only reduces the risk of solid waste storage, but also recycles zinc in aluminum powder slag, reduces zinc loss, and makes valuable use of the characteristics of aluminum and aluminum oxide in the aluminum powder slag, utilizes the complexation mechanism of aluminum salt to remove fluoride ions, reduces the fluoride ion content, and solves the adverse effects of increased fluoride ions in the system and the difficulty in stripping the zinc skin of the zinc smelting electrolysis cathode.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metallurgy processes, and in particular to a method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag. Background Art

[0002] The conventional wet zinc smelting system produces about 3 tons of aluminum powder slag from the cathode aluminum plate brushing process of zinc smelting every year. Due to the high zinc and aluminum content in the aluminum powder slag and the fact that it is often accompanied by some acidic liquid during the brushing process, spontaneous combustion often occurs during the heat generated during the oxidation of zinc and aluminum, which is a solid waste dump. This not only causes environmental accidents, but also increases the amount of solid waste dumps. In order to prevent the occurrence of this environmental accident, a method for recycling and utilizing the aluminum powder slag from the cathode aluminum plate brushing process of zinc smelting needs to be invented. Summary of the Invention

[0003] In order to solve the problem in the prior art that the solid waste storage of cathode aluminum plate brush plate aluminum powder slag cannot be reduced, the present invention provides a method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag.

[0004] The present invention adopts the following technical solutions:

[0005] A method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag, characterized by comprising the following steps:

[0006] Step 1: Add cathode aluminum plate brush plate aluminum powder slag to zinc smelting waste electrolyte to form a mixed solution; the amount of aluminum powder slag added is (20-40) kg / m 3 Zinc smelting spent electrolyte;

[0007] Step 2: Adding the mixed solution from step 1 to the neutral leaching process for zinc smelting to perform neutral leaching. The neutral leaching process for zinc smelting includes: using zinc concentrate calcine (zinc smelting raw material) and an oxidant as raw materials, introducing low-pressure air, and performing neutral leaching, with an end point pH value of 4.8-5.2. The oxidant is used to oxidize divalent iron ions and promote the dissolution of aluminum powder in an acidic environment. Elemental aluminum serves as a reducing agent, and pyrolusite serves as an oxidant, promoting the rapid dissolution of elemental aluminum to provide qualified liquid for the next process.

[0008] After neutral leaching, a flocculant with a concentration of (0.1-0.3)% is added (the concentration here refers to the ratio of the weight of the added flocculant to the volume of the liquid) to adsorb cationic impurities (such as arsenic, antimony, and germanium) in the solution, and then liquid-solid separation is performed to obtain the supernatant and bottom flow of the intermediate leaching;

[0009] The supernatant in the intermediate leaching is purified in three stages to obtain new zinc electrolysis solution, and the bottom flow of the intermediate leaching is mainly composed of aluminum-fluorine complexes;

[0010] Step 3: Take the intermediate leaching bottom stream, add zinc electrolysis wastewater, and perform acid leaching. The end point pH is 1.5-2.5, preferably 2.0. After acid leaching, an acid supernatant and an acid leaching bottom stream are obtained. The acid supernatant is returned to step 2 for neutral leaching. The purpose of acid leaching is to leach more zinc ions into the acid supernatant and further recover zinc.

[0011] Step 4: Take the acid leaching bottom flow, add heavy calcium powder to adjust the pH value to 5.0, and then perform flotation. After flotation, filter press to form leaching residue. Flotation is to maximize the floatation of silver in the acid leaching bottom flow.

[0012] Because the end point pH value of acid leaching is around 2.0, it is not conducive to the addition of reagents in the flotation workshop, so it is necessary to add alkaline auxiliary materials to adjust the pH value to 5.0; the liquid after flotation filtration is returned to neutral leaching to recover aluminum ions and zinc ions.

[0013] Step 5: The acidic leaching residue from step 4 is placed in a multi-hearth furnace, oxygen and coke particles are introduced, and the fluorine-containing complex is removed by pyrolysis roasting.

[0014] The present invention adds dissolved aluminum powder slag during the neutral leaching process of zinc smelting, and controls the amount of aluminum powder slag added to (20-40) kg / m 3 Liquid, during the entire leaching process, as the pH value increases, fluoride ions and aluminum ions form complexes and precipitate, and then acid leaching is to better leach the zinc ions in the aluminum powder slag. After acid leaching, the excess aluminum ions in the acid supernatant are returned for neutral leaching and can be further utilized. Then the acid leaching slag enters the flotation process and the pH value is adjusted to continue to form complexes. In this way, fluoride ions enter the leaching slag and are removed at high temperature in the multi-chamber furnace.

[0015] The leaching process of the present invention includes two steps: neutral leaching and acid leaching. The neutral leaching is a process of dissolving zinc in roasted sand into liquid using dilute sulfuric acid, while controlling the pH value of the final tank and removing impurities such as arsenic, antimony and germanium through the hydrolysis of iron. The acid leaching is a process of continuing to leach zinc in neutral leaching residue to the maximum extent under the condition of relatively high acidity, ensuring that zinc enters the solution as much as possible, while controlling the entry of impurities into the liquid.

[0016] Furthermore, the sulfuric acid content in the zinc smelting waste electrolyte is 150-200 g / L, and the Zn content is 40-65 g / L; the zinc content in the aluminum powder slag is 15%-20%, and the rest is aluminum metal element and aluminum oxide.

[0017] Furthermore, the oxidant is pyrolusite and air (with sufficient oxygen), the pyrolusite particle size is 120 mesh, the zinc concentrate calcine contains 55% zinc, and the particle size is +80 mesh ≤ 5%, -200 mesh ≥ 78%.

[0018] Furthermore, the manganese dioxide content in the pyrolusite is ≥50%, and the molar ratio of the manganese ions in the added pyrolusite to the divalent iron ions in the solution is (0.6-0.7):1.

[0019] Furthermore, the pressure of the low-pressure wind is 0.4 MPa, and the ventilation volume is 10m 3 / h.

[0020] Furthermore, the content of the heavy calcium powder is ≥92%.

[0021] Furthermore, the temperature in the multi-chamber furnace is 680-720°C.

[0022] The main principle of the present invention is: the zinc and aluminum in the aluminum powder slag mainly come from the cathode aluminum plate brushing process (i.e., the aluminum powder slag from the zinc smelting cathode aluminum plate brushing process), and the main forms are zinc metal element and zinc oxide, as well as aluminum metal element and aluminum oxide. The zinc content is 15%-20%, and the rest is basically aluminum metal and aluminum oxide. The aluminum powder slag is fully dissolved in the acidic waste liquid to form zinc sulfate and aluminum sulfate acidic liquid. According to the aluminum-containing adsorbent in the acidic solution, aluminum has a strong coordination ability for fluorine, so it has good selectivity for fluorine in the zinc smelting waste electrolyte, and has a good defluorination effect on the zinc smelting waste electrolyte. The action mechanism of aluminum salt in removing fluoride ions includes adsorption, ion exchange, and complexation sedimentation. ① The amorphous Al (OH) 3 with a large surface area generated in the aluminum salt defluorination process can produce hydrogen bond adsorption for fluorine. The fluoride ion radius is small and the electronegativity is strong. ② F - With OH - The radius is similar and the charge is the same. In the process of aluminum salt defluorination, after being added to the solution, Al 13 O4 (OH) 14 7+ Polycations and the amorphous Al(OH)3 precipitate formed after hydrolysis, in which OH - and F - An exchange occurs. - Can with Al 3+ Formed from AlF 2+ to AlF 3- The 6 complexes are complexed and settled to remove fluorine. Therefore, after adding aluminum powder slag to zinc smelting wastewater, zinc sulfate and aluminum sulfate acidic liquid are formed. No arsenic gas is produced in this process. When added to the neutral leaching process, the amount of aluminum powder slag added is controlled to (20-40) kg / m 3 Liquid, and continuously and stably enters the system, which promotes the gradual reduction of fluoride ion content in zinc smelting waste electrolyte, thereby ensuring normal stripping of electrolytic cathode zinc.

[0023] Reaction formula:

[0024] Al2O3+3H2SO4=Al2(SO4)3+3H2O

[0025] Al 3+ +3H2O=Al(OH)3+3H +

[0026] The present invention aims to remove fluoride ions from zinc smelting waste electrolyte using aluminum from aluminum powder slag, dissolving zinc into the waste electrolyte for recovery. The mechanism of action of aluminum salt in removing fluoride ions includes adsorption, ion exchange, and complexation sedimentation.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] The present invention provides a method for recycling aluminum powder slag from zinc smelting cathode aluminum plate brushes, which comprises adding aluminum powder slag to the acidic waste electrolyte from zinc smelting, fully dissolving the slag, and allowing the fluorine-aluminum complex to enter the acidic leaching slag, so that the fluorine content of the zinc smelting waste electrolyte is controlled below the normal value of 40 mg / L, and the fluorine-aluminum complex in the leaching slag is removed by high-temperature roasting in a multi-chamber furnace.

[0029] The present invention recycles aluminum powder slag generated during the brushing process of aluminum plates used in zinc smelting cathodes, ensuring safety and environmental protection. No additional harmful gases are generated during the entire invention process, reducing the risk of solid waste storage. Furthermore, the invention recycles zinc from the aluminum powder slag, reducing zinc metal loss. Furthermore, the invention effectively utilizes the properties of aluminum and aluminum oxide in the aluminum powder slag, fully utilizing the complexation mechanism of aluminum salts to remove fluoride ions, thereby achieving the purpose of removing fluoride from the system and reducing the fluoride ion content in the system. This resolves the adverse effects of increased fluoride ions in the system, which can lead to difficulty in stripping the zinc skin from the zinc smelting electrolytic cathode. The present invention addresses the risk of spontaneous combustion during solid waste storage and the adverse effects of high fluoride ion content on the system.

[0030] The present invention fully realizes the valuable utilization of aluminum powder slag, recovers zinc metal in the aluminum powder slag, utilizes the aluminum metal properties in the aluminum powder slag, reduces the fluoride ion content in the zinc electrolysis waste liquid, and avoids the adverse effect of high fluoride ion content on the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto. In the following examples, the pyrolusite has a particle size of 120 mesh, a manganese dioxide content of ≥50%, and the zinc smelting waste electrolyte (also referred to as zinc electrolysis waste liquid) has a Zn content of 40-65 g / L and an H2SO4 content of 150-200 g / L.

[0033] The present invention provides a method for recycling aluminum powder slag from the brushing of zinc smelting cathode aluminum plates, comprising the following steps: adding the aluminum powder slag from the brushing of zinc smelting cathode aluminum plates to zinc electrolysis wastewater; after being fully dissolved under a certain stirring intensity, transporting the aluminum powder slag to a neutral leaching oxidation tank; as the pH value increases during the neutral leaching process, aluminum fluoride complex precipitates are formed, and acid leaching is performed along the intermediate leaching bottom flow; during the flotation process of the acid leaching bottom flow, heavy calcium powder is added to adjust the pH value, and the acid leaching slag is placed in a rotary kiln, and oxygen and coke particles are introduced, so that fluorine forms a gas that volatilizes and opens a path, and aluminum enters the water-quenched slag. Under the premise of ensuring safety and environmental protection, the present invention recycles the aluminum powder slag generated in the brushing process of zinc smelting cathode aluminum plates, not only reducing the storage of solid waste, but also recovering zinc in the aluminum powder slag, and effectively utilizing the properties of aluminum and aluminum oxide in the aluminum powder slag to achieve the purpose of removing fluorine from the system. The risk of solid waste storage and the adverse effects of fluoride ions on the system are solved. The method of the present invention reduces the risk of solid waste storage, does not generate additional harmful gases during the entire invention process, and effectively utilizes the properties of aluminum metal and aluminum oxide in aluminum powder slag to reduce the fluoride ion content in the system, thereby avoiding the adverse effects of high fluoride ion content on the system.

[0034] Example 1

[0035] When the fluorine content in the zinc smelting waste electrolyte (hereinafter referred to as waste liquid) reaches 45 mg / L, aluminum powder slag is added to the waste liquid. In this embodiment, the amount of aluminum powder slag added is 20 kg / m 3 Waste liquid, to ensure that the aluminum powder slag is fully dissolved, the waste liquid continuously and stably enters the system, and ensures that there is enough aluminum salt in the liquid. The mixed liquid is added to the zinc smelting neutral leaching process for neutral leaching; the zinc smelting neutral leaching process includes: using zinc concentrate roasted sand (zinc smelting raw material) and pyrolusite as raw materials, passing low-pressure air, and performing neutral leaching, with the end point pH value of 4.8-5.2; the pressure of the low-pressure air is 0.4MPa, and the ventilation volume is 10m 3After neutral leaching, a 0.1-0.3% concentration of polyacrylamide flocculant is added to absorb cationic impurities in the solution, allowing them to settle in a thickener for liquid-solid separation. The supernatant undergoes three purification stages to produce fresh electrolytic solution, while the zinc in the aluminum slag is recovered in the supernatant. The intermediate leach underflow (primarily aluminum-fluorine complexes) is added to zinc electrolysis wastewater for acid leaching, achieving an endpoint pH of 1.5-2.5. The acid supernatant returns to the neutral leaching process, while the acid leaching underflow enters the thickener in the silver recovery section. It then passes through the ore tank (the reaction tank where calcium carbonate powder is added in the silver flotation process), where calcium carbonate powder is added to gradually adjust the pH to above 5.0. The thickened silver flotation tailings underflow is filtered and pressed in a diaphragm automatic chamber filter press to reduce the moisture content of the acid leaching residue. The acid leaching residue from the acid leaching underflow was placed in a multi-hearth furnace at a temperature of 680-720°C. Oxygen and coke particles were introduced, and fluorine-containing complexes were removed by pyrolysis. A fresh electrolytic solution sample was tested and found to contain 29.25 mg / l of fluorine. The cathode zinc scale did not show signs of difficulty in peeling.

[0036] Example 2

[0037] When the fluorine content in the zinc smelting waste electrolyte reaches 55 mg / l, aluminum powder slag is added to the waste liquid. In this embodiment, 30 kg / m 3 Liquid, to ensure that the aluminum powder slag is fully dissolved, the waste liquid continuously and stably enters the system, and ensures that there is enough aluminum salt in the liquid. The mixed liquid is added to the zinc smelting neutral leaching process for neutral leaching; the zinc smelting neutral leaching process includes: using zinc concentrate roasted sand (zinc smelting raw material) and pyrolusite as raw materials, introducing low-pressure air, and conducting neutral leaching. The end point pH value is 4.8-5.2, the pressure of the low-pressure air is 0.4MPa, and the ventilation volume is 10m 3 / h; after neutral leaching, a 0.1-0.3% concentration of polyacrylamide flocculant is added to absorb cationic impurities in the solution, allowing them to settle into a thickener for liquid-solid separation. The supernatant then undergoes three purification stages to produce fresh electrolytic solution, and the zinc in the aluminum slag is recovered in the supernatant. The intermediate leach underflow is then treated with zinc electrolysis wastewater for acid leaching, with an endpoint pH of 1.5-2.5. The acid supernatant returns to the neutral leaching process, and the underflow enters the thickener in the silver recovery section. After passing through the raw ore tank, the pH is gradually adjusted to above 5.0 by adding heavy calcium carbonate powder. The thickened underflow from the silver flotation tailings is filtered and pressed in a membrane automatic chamber filter press to reduce moisture in the acid leaching residue. The acid leaching residue from the underflow is placed in a multi-chamber furnace at a temperature of 680-720°C, where oxygen and char are introduced. Fluorine-containing complexes are then removed by pyrolysis. The fluorine content of the new electrolytic liquid sample was 35 mg / l, and the zinc scale of the electrolytic cathode was not difficult to peel off.

[0038] Example 3

[0039] When the fluorine content of the fluorine-containing solution for wet zinc electrolysis reaches 65 mg / l, aluminum powder slag is added to the waste liquid. In this embodiment, 40 kg / m 3 Liquid, to ensure that the aluminum powder slag is fully dissolved, the waste liquid continuously and stably enters the system, and ensures that there is enough aluminum salt in the liquid. The mixed liquid is added to the zinc smelting neutral leaching process for neutral leaching; the zinc smelting neutral leaching process includes: using zinc concentrate roasted sand (zinc smelting raw material) and pyrolusite as raw materials, introducing low-pressure air, and performing neutral leaching. The end point pH value is 4.8-5.2, the low-pressure air pressure is 0.4Map, and the ventilation volume is 10m 3 / h; after neutral leaching, a 0.1-0.3% concentration of polyacrylamide flocculant is added to absorb cationic impurities in the solution, allowing them to settle into a thickener for liquid-solid separation. The supernatant then undergoes three purification stages to produce fresh electrolytic solution, and the zinc in the aluminum slag is recovered in the supernatant. The intermediate leach underflow is then treated with zinc electrolysis wastewater for acid leaching, with an endpoint pH of 1.5-2.5. The acid supernatant returns to the neutral leaching process, and the underflow enters the thickener in the silver recovery section. After passing through the raw ore tank, the pH is gradually adjusted to above 5.0 by adding heavy calcium carbonate powder. The thickened underflow from the silver flotation tailings is filtered and pressed in a membrane automatic chamber filter press to reduce moisture in the acid leaching residue. The acid leaching residue from the underflow is placed in a multi-chamber furnace at a temperature of 680-720°C, where oxygen and char are introduced. Fluorine-containing complexes are then removed by pyrolysis. The fluorine content of the new electrolytic liquid sample was 32.5 mg / l, and the zinc scale of the electrolytic cathode was not difficult to peel off.

[0040] The embodiments described above are only preferred embodiments of the present invention and are only used to explain the present invention, not to limit the scope of implementation of the present invention. For those skilled in the art, it is of course possible to easily make other implementation methods by replacing or changing the technical content disclosed in this specification. Therefore, all changes and improvements made to the principles and process conditions of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag, characterized in that: The following steps are involved: Step 1: adding cathode aluminum plate brush plate aluminum powder slag to zinc smelting waste electrolyte to form a mixed solution; the zinc content of the aluminum powder slag is 15%-20%, and the remainder is aluminum metal and aluminum oxide; the sulfuric acid content of the zinc smelting waste electrolyte is 150-200g / L, and the Zn content is 40-65g / L; the amount of aluminum powder slag added per cubic meter of the zinc smelting waste electrolyte is 20-40kg; Step 2: adding the mixed solution from step 1 to the neutral leaching process of zinc smelting for neutral leaching; adding a flocculant after the neutral leaching is completed to obtain a supernatant and a bottom flow from the intermediate leaching; The supernatant obtained from the intermediate leaching is purified in three stages to obtain a new zinc electrolysis solution; The neutral leaching process of zinc smelting includes: using zinc concentrate calcine and an oxidant as raw materials, introducing low-pressure air, and performing neutral leaching, with an end point pH value of 4.8-5.2, wherein the oxidant is pyrolusite; Step 3: taking the intermediate leaching bottom flow, adding zinc electrolysis waste liquid, and performing acid leaching, obtaining an acid supernatant and an acid leaching bottom flow after acid leaching, and returning the acid supernatant to step 2 for neutral leaching; Step 4: Take the acid leaching bottom flow, add heavy calcium powder to adjust the pH value to 5.0, and then perform flotation. After flotation, perform filter pressing to form leaching residue; Step 5: Take the leached residue from step 4, place it in a multi-hearth furnace, introduce oxygen and coke particles, and remove the fluorine-containing complex by pyrolysis roasting.

2. The method for recycling aluminum powder slag from zinc smelting cathode aluminum plate brush plate according to claim 1, characterized in that: The acid leaching endpoint pH value is 1.5-2.

5.

3. The method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag according to claim 1, characterized in that: The flocculant is anionic polyacrylamide.

4. The method for recycling aluminum powder slag from zinc smelting cathode aluminum plate brush plate according to claim 1, characterized in that: The content of the heavy calcium powder is ≥92%.

5. The method for recycling zinc smelting cathode aluminum plate brush plate aluminum powder slag according to claim 1, characterized in that: The temperature of the multi-hearth furnace is 680-720°C.

Images