Method for recycling zinc slag of hot-dip galvanizing line

Abstract

The invention discloses a method for recycling zinc slag of a hot-dip galvanizing line, and relates to the technical field of hot-dip galvanizing and aluminum. The method comprises the following steps: firstly, feeding a zinc-plating slag raw material into a resistance heating melting furnace; a resistance heating melting furnace is opened, the zinc plating slag is melted into metal iron slag and a zinc-aluminum alloy melt, and the metal iron slag is not melted; the obtained alloy melt is discharged into a liquation pool; discharging the obtained zinc-aluminum alloy liquid; the obtained zinc-aluminum alloy block enters a replacement pool, and the replacement pool is internally filled with a FeSO4 solution in advance; the obtained mixed solution of the Al2 (SO4) 3 solution and the ZnSO4 solution is filtered and then added into an electrolytic tank, a lead plate serves as a cathode, and an aluminum plate serves as an anode; according to the method, the metal zinc deposited on the aluminum plate is stripped, the metal zinc in the zinc plating slag can be separated from the metal iron and the metal aluminum, the metal zinc is effectively recycled, the process is simple, the energy consumption and the processing cost are low, the production can be continuous, and the production efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of hot-dip galvanized aluminum, and in particular to a method for recycling zinc slag from a hot-dip galvanizing line. Background Art

[0002] Hot-dip galvanizing is a relatively effective and convenient method for steel corrosion protection. Its coating has excellent sacrificial corrosion protection. Hot-dip aluminum coating is dense and has a long durability. Zinc-aluminum alloy coating is widely used because it combines the durable protection characteristics of aluminum and the cathodic protection characteristics of zinc. The performance of the coating is superior to that of single element coating, and the corrosion resistance is several times higher than that of pure zinc coating.

[0003] Galvanizing slag is a waste residue formed during the galvanizing process of steel. On the one hand, galvanizing slag is a hazardous waste recognized by the state. If not properly handled, it will cause harm to the environment. On the other hand, the metallic zinc content of galvanizing slag is generally above 90%, making it a valuable secondary zinc resource. Therefore, a method for recycling and reusing zinc slag from hot-dip galvanizing lines is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to address the defects and shortcomings of the existing technology and provide a method for recycling and reusing zinc slag from a hot-dip galvanizing line with a simple structure, reasonable design and easy use. The method can separate the metallic zinc from the metallic iron and metallic aluminum in the galvanizing slag, effectively recover the metallic zinc, and has a simple process, low energy consumption and processing costs, continuous production and high production efficiency.

[0005] To achieve the above object, the technical solution adopted by the present invention is: it comprises the following steps: Step 1: First, the galvanized slag raw material is put into the interior of the resistance heating melting furnace, and then the furnace cover of the resistance heating melting furnace is sealed, and inert gas is input into the interior of the resistance heating melting furnace; Step 2: Open the resistance heating melting furnace to melt the galvanized slag into metallic iron slag and zinc-aluminum alloy melt, while the metallic iron slag does not melt; Step 3: discharging the alloy melt obtained in step 2 into a smelting pool, removing the upper slag, and discharging the lower smelting melt to obtain zinc-aluminum alloy liquid; Step 4: Discharge the zinc-aluminum alloy liquid obtained in step 3, and then cool it to obtain a zinc-aluminum alloy block; Step 5: Place the zinc-aluminum alloy block obtained in step 4 into a replacement tank, which is pre-filled with a FeSO4 solution. The zinc-aluminum alloy block is fully contacted with the FeSO4 solution to react, replacing the elemental iron in the FeSO4 solution to obtain a mixture of Al2(SO4)3 solution and ZnSO4 solution. Step 6: Filter the mixed solution of Al2(SO4)3 solution and ZnSO4 solution obtained in step 5, and add it to the interior of the electrolytic cell, using the lead plate as the cathode and the aluminum plate as the anode; during electrolysis, metallic zinc is deposited on the surface of the aluminum plate; Step 7: peel off the metallic zinc deposited on the aluminum plate in step 6.

[0006] Preferably, the inert gas in step 1 is one of argon, helium, nitrogen and xenon.

[0007] Preferably, the heating temperature in the resistance heating melting furnace in step 2 is 670°C to 690°C.

[0008] Preferably, the temperature in the smelting pool in step 3 is maintained at 660°C to 680°C.

[0009] Preferably, the cooling of the zinc-aluminum alloy liquid in step 4 is performed by providing a cooler in the middle of an annular cooling pool.

[0010] The beneficial effects of the present invention are: 1. According to the different melting points of metal zinc, metal iron and metal aluminum, metal iron can be separated from the middle part of metal zinc and metal aluminum; 2. Metallic zinc and metallic aluminum are replaced by FeSO4 solution, and then the zinc in the solution is electrolyzed to separate metallic zinc from metallic aluminum, effectively recovering metallic zinc. The process is simple, with low energy consumption and processing costs, continuous production, and high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 It is a comparison chart of experimental data of a specific implementation method. DETAILED DESCRIPTION

[0013] The present invention will be further described below with reference to the accompanying drawings. Example 1:

[0014] The technical solution adopted in this embodiment is: it includes the following steps: Step 1: First, the galvanized slag raw material is put into the interior of the resistance heating melting furnace, and then the furnace cover of the resistance heating melting furnace is sealed, and an inert gas is input into the interior of the resistance heating melting furnace; the inert gas is argon; Step 2: Open the resistance heating melting furnace to melt the galvanized slag into metallic iron slag and zinc-aluminum alloy melt, while the metallic iron slag does not melt; the heating temperature in the resistance heating melting furnace is 690° C. Step 3: discharging the alloy melt obtained in step 2 into a smelting pool, maintaining the temperature of the smelting pool at 670° C., removing the upper slag, and discharging the lower smelting melt to obtain zinc-aluminum alloy liquid; Step 4: Discharge the zinc-aluminum alloy liquid obtained in step 3, and then cool it to obtain a zinc-aluminum alloy block; the zinc-aluminum alloy liquid is cooled by a cooler provided in the middle of an annular cooling pool; Step 5: Place the zinc-aluminum alloy block obtained in step 4 into a replacement tank, which is pre-filled with a FeSO4 solution. The zinc-aluminum alloy block is fully contacted with the FeSO4 solution to react, replacing the elemental iron in the FeSO4 solution to obtain a mixture of Al2(SO4)3 solution and ZnSO4 solution. Step 6: Filter the mixed solution of Al2(SO4)3 solution and ZnSO4 solution obtained in step 5, and add it to the interior of the electrolytic cell, using the lead plate as the cathode and the aluminum plate as the anode; during electrolysis, metallic zinc is deposited on the surface of the aluminum plate; Step 7: peel off the metallic zinc deposited on the aluminum plate in step 6.

[0015] After adopting the above structure, the beneficial effects of this specific embodiment are: 1. According to the different melting points of metal zinc, metal iron and metal aluminum, metal iron can be separated from the middle part of metal zinc and metal aluminum; 2. Metallic zinc and metallic aluminum are replaced by FeSO4 solution, and then the zinc in the solution is electrolyzed to separate metallic zinc from metallic aluminum, effectively recovering metallic zinc. The process is simple, with low energy consumption and processing costs, continuous production, and high production efficiency. Example 2:

[0016] In this embodiment, in step 1, an inert gas is introduced into the interior of the resistance heating melting furnace, and the inert gas is helium; in step 2, the heating temperature in the resistance heating melting furnace is 670°C; in step 3, the temperature in the molten pool is maintained at 660°C; and the remaining principles are the same as those in embodiment 1. Example 3:

[0017] In this embodiment, in step 1, an inert gas is introduced into the interior of the resistance heating melting furnace, and the inert gas is xenon. In step 2, the heating temperature in the resistance heating melting furnace is 690° C.; in step 3, the temperature in the molten pool is maintained at 680° C.; and the remaining principles are the same as those in embodiment 1.

[0018] The components of the galvanizing slag in Examples 1 to 3 were tested before and after extraction. The experimental data are as follows: Figure 1 As shown, the metallic zinc in the galvanizing slag is recovered, and the recovery efficiency exceeds 80%. The recovery efficiency is high, the process is simple, and the production efficiency is high.

[0019] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for recycling zinc slag from a hot-dip galvanizing line, characterized by: It contains the following steps: Step (1): firstly, the galvanized slag raw material is put into the interior of the resistance heating melting furnace, then the furnace cover of the resistance heating melting furnace is sealed, and an inert gas is input into the interior of the resistance heating melting furnace; Step (2), opening the resistance heating melting furnace to melt the galvanized slag into metallic iron slag and zinc-aluminum alloy melt, without melting the metallic iron slag; Step (3), discharging the alloy melt obtained in step (2) into the interior of the smelting pool, removing the upper smelting slag, and discharging the smelting melt on the lower side to obtain the zinc-aluminum alloy liquid; Step (4), discharging the zinc-aluminum alloy liquid obtained in step (3), and then cooling it to obtain a zinc-aluminum alloy block; Step (5), placing the zinc-aluminum alloy block obtained in step (4) into a replacement tank, which is pre-filled with a FeSO4 solution, and fully contacting the zinc-aluminum alloy block with the FeSO4 solution to react and replace the elemental iron in the FeSO4 solution to obtain a mixture of Al2(SO4)3 solution and ZnSO4 solution; Step (6), filtering the mixed solution of Al2(SO4)3 solution and ZnSO4 solution obtained in step (5), and adding it to the interior of the electrolytic cell, using the lead plate as the cathode and the aluminum plate as the anode; during electrolysis, metallic zinc is deposited on the surface of the aluminum plate; Step (7), peeling off the metallic zinc deposited on the aluminum plate in step (6).

2. The method for recycling zinc slag from a hot-dip galvanizing line according to claim 1, characterized in that: The inert gas in step (1) is one of argon, helium, nitrogen and xenon.

3. The method for recycling zinc slag from a hot-dip galvanizing line according to claim 1, characterized in that: The heating temperature in the resistance heating melting furnace in step (2) is 670°C to 690°C.

4. The method for recycling zinc slag from a hot-dip galvanizing line according to claim 1, wherein: The temperature in the smelting pool in step (3) is maintained at 660°C to 680°C.

5. The method for recycling zinc slag from a hot-dip galvanizing line according to claim 1, characterized in that: The cooling of the zinc-aluminum alloy liquid in step (4) is achieved by providing a cooler in the middle of an annular cooling pool.

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