CN117431411B - Smelting method of recycled aluminum - Google Patents

Abstract

The invention provides a method for smelting recycled aluminum and relates to the field of recycled aluminum alloy smelting. The smelting method of recycled aluminum includes the following steps: smelting the aluminum raw material to be regenerated at 580-680°C for 75-125 minutes to obtain a molten liquid; and during the smelting process, the upper area of the aluminum raw material is located Within the range of the flames of the oxidizing atmosphere, the lower region of the aluminum raw material is located within the range of the flames of the reducing atmosphere; the molten liquid is refined to obtain a regenerated aluminum liquid. The above-mentioned smelting method smelts the aluminum raw material to be recycled in the temperature range of 580 to 680°C. On the one hand, the oxidizing atmosphere is used to quickly increase the furnace temperature, causing the aluminum raw materials to quickly melt and improve the smelting efficiency. On the other hand, the lower part of the aluminum raw material is burned in the reducing atmosphere to reduce the burning loss of the aluminum liquid and alloy. Using the above-mentioned smelting method of recycled aluminum can not only improve the production efficiency of recycled aluminum, but also have a lower burning loss rate.

Description

Smelting method of recycled aluminum

Technical field

The present invention relates to the field of recycled aluminum alloy smelting, and in particular to a method for smelting recycled aluminum.

Background technique

Aluminum is a recyclable resource with good recyclability. Recycled aluminum is made by re-smelting scrap aluminum and scrap aluminum alloy materials to obtain aluminum alloy or aluminum metal. The development and utilization of recycled aluminum resources, or even the use of recycled aluminum, can not only save energy and reduce production costs, but also reduce carbon emissions by 95% compared with primary aluminum, and can also reduce environmental pollution and improve the ecological environment. Therefore, the research on process equipment for recycled aluminum and the future high-quality and sustainable development of the aluminum industry are of great significance.

When smelting recycled aluminum, high-temperature smelting technology is usually used to fully melt the scrap aluminum material. However, using a melting temperature above 850°C will cause oxidation and burning loss of recycled aluminum and its alloys, resulting in a reduction in the scrap aluminum recovery rate, which is less than 90%, affecting product quality, and the energy consumption is quite high. The fuel consumption per ton of product is generally More than 90 kg, even up to 100-120 kg. The above problems can be partially solved by using low-temperature smelting method. However, the reduction of smelting temperature will inevitably extend the smelting time and affect the production efficiency of recycled aluminum.

Contents of the invention

The main purpose of the present invention is to provide a method for smelting recycled aluminum to solve the technical problems of high burning loss or long smelting time of recycled aluminum.

In order to achieve the above object, the present invention provides a method for smelting recycled aluminum, which includes the following steps:

The aluminum raw material to be regenerated is smelted at 580-680°C for 75-125 minutes to obtain a molten liquid. During the smelting process, the upper area of the aluminum raw material is located within the range of the oxidizing atmosphere and the lower area of the aluminum raw material is located within the range of the reducing atmosphere.

The molten liquid is refined to obtain regenerated aluminum liquid.

According to the embodiment of the present application, the steps of smelting the aluminum raw material to be regenerated at 580 to 680°C for 75 to 125 minutes include:

Within 10-25 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 580-600°C.

Raise the temperature to 650-680°C, keep it for 25-50 minutes, and proceed to the second stage of melting.

Adjust the temperature to 580-630°C, maintain melting for 40-50 minutes, and proceed to the third stage of melting.

According to the embodiment of the present application, during the first stage smelting, the second stage smelting and the third stage smelting, the melt is stirred for 2 to 8 times.

According to an embodiment of the present application, the oxidizing atmosphere fire is performed under the condition that the ratio of natural gas to combustion air is less than 1:2.

Reducing atmosphere flamethrowing is a combustion flamethrowing condition where the ratio of natural gas to combustion air is greater than 1:2.

According to the embodiment of the present application, the melting temperature in the first stage is raised to 650-680°C at a rate of 5-10°C/min.

According to the embodiment of the present application, before the aluminum raw material to be regenerated is smelted, it also includes:

The aluminum raw material to be regenerated is passed through the heating furnace wall at 500-600°C for reflection baking;

Continue to directly grill the aluminum raw material to be regenerated at 450-550°C with a long flame, and blow off the separated hardened paint film or hardened grease with air heated by waste heat.

According to the embodiment of the present application, the duration of reflection baking is 10~15mim.

After reflection baking for 10 to 15 minutes, direct grilling is performed. The duration of direct grilling is 15 to 25 minutes.

According to the embodiment of the present application, the flow rate of air is 10~20 Nm³/h.

According to the embodiment of the present application, the step of refining the melt includes:

When the temperature of the aluminum liquid in the furnace is 680°C to 720°C, add 0.20% refining agent. The refining time is more than 10 to 15 minutes. The height of the waves set off during refining is between 30 to 80mm. After refining, let it stand for 8 to 12 minutes to remove the slag. .

According to the embodiment of the present application, the step of smelting the aluminum raw material to be regenerated occurs in the smelting furnace, and the step of refining the molten liquid occurs in the refining furnace.

After the molten liquid in the smelting furnace is transferred to the refining furnace, the smelting furnace is stripped of iron, slag, and cleaned, and then enters the next smelting cycle.

The above-mentioned smelting method of recycled aluminum smelts the aluminum raw material to be recycled in the temperature range of 580 to 680°C. On the one hand, the oxidizing atmosphere is used to quickly increase the furnace temperature, causing the aluminum raw materials to quickly melt and improve the smelting efficiency. On the other hand, the lower part of the aluminum raw material is burned in the reducing atmosphere to reduce the burning loss of the aluminum liquid and alloy. Using the above-mentioned smelting method of recycled aluminum can not only improve the production efficiency of recycled aluminum, but also have a lower burning loss rate.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without exerting creative efforts.

FIG. 1 is a flow chart of a method for smelting recycled aluminum according to an embodiment of the present application.

The realization of the purpose, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings.

Detailed ways

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

It should be noted that all directional indications (such as up, down...) in the embodiments of the present invention are only used to explain the relative positional relationship, movement, etc. between the components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication changes accordingly.

In addition, descriptions such as "first", "second", etc. in the present invention are for descriptive purposes only and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features.

Moreover, the technical solutions in the various embodiments of the present invention can be combined with each other, but it must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions appears to be contradictory or cannot be realized, such combination of technical solutions should be considered. It does not exist and is not within the protection scope required by the present invention.

In order to achieve the above object, the present invention provides a method for smelting recycled aluminum. See Figure 1, which includes the following steps:

S100: Smelt the aluminum raw material to be regenerated at 580-680°C for 75-150 minutes to obtain a molten liquid. During the smelting process, the upper area of the aluminum raw material is located within the range of the oxidizing atmosphere and the lower area of the aluminum raw material is located within the range of the reducing atmosphere.

Aluminum raw materials to be recycled include scrap aluminum and scrap aluminum alloy materials or scrap containing aluminum. Usually, aluminum raw materials of similar categories or products of the same type with similar composition content are smelted in the same batch. In order to increase the smelting efficiency, the aluminum raw materials to be regenerated are fed in broken pieces, such as in a step-by-step manner, in the form of a pile.

When the aluminum raw material to be regenerated is relatively clean and contains few impurities, such as containing less grease or paint, it can be smelted directly.

The smelting process of the aluminum raw material to be regenerated is usually carried out in a smelting furnace. During the smelting process, the furnace temperature in the smelting furnace is controlled to be 580~680°C. The heat source of the smelting furnace is mainly the flame nozzle. The combustion of the flame nozzle increases the temperature of the smelting furnace. The flame nozzle includes a flame nozzle that sprays an oxidizing atmosphere on the upper area of the aluminum raw material and a flame nozzle that sprays a reducing atmosphere on the lower area of the aluminum raw material. Of course, in some embodiments, it also includes spraying in other areas. The spout of fire.

Oxidizing atmosphere mainly refers to a flame atmosphere produced when the air supply is sufficient and the fuel is completely burned.

Reducing atmosphere refers to an atmosphere in which reducing gases such as hydrogen, carbon monoxide and converted natural gas are the main components. This atmosphere usually contains no or very small amounts of oxidizing gases. For example, converted natural gas is composed of high-purity methane and a small amount of hydrogen. It burns with a clean flame and contains no oxidizing components.

If the smelting furnace is not used for primary smelting, the smelting furnace includes the aluminum-containing molten liquid formed by the previous smelting cycle. The stockpile is located above the melt.

The upper area of the aluminum raw material is located within the range of the flame in the oxidizing atmosphere, that is, the upper block area uses a flame nozzle to burn and melt the block in the oxidizing atmosphere. The lower area of the aluminum raw material is located within the range of the reducing atmosphere, that is, the lower block area uses a flame nozzle to burn and burn in the reducing atmosphere. Since the pile is located on the molten liquid, it can also be understood that the flame nozzle is used to aim at the liquid level area of the molten liquid to burn, and the molten liquid is in a reducing atmosphere, thereby preventing excessive oxidation of the molten liquid and causing burning damage.

Specifically, flame nozzles are arranged on both sides of the main chamber furnace to spray fire at the furnace materials. The upper nozzles in the furnace are used to directly spray flames on the surface of the furnace materials for melting. The flame penetrates into the furnace materials pile through the gaps between the furnace materials. , the heat is quickly transferred to the middle of the furnace material, causing the material in the middle and bottom of the material pile to quickly rise in temperature and melt. Specifically, the upper nozzle is facing the upper middle part of the pile.

The flame nozzles on both sides of the furnace are arranged in upper and lower zones. The upper block area uses the upper flame nozzle to burn and melt the material block using an oxidizing atmosphere. The lower block area is burned in a reducing atmosphere through the lower flame nozzle. The flame injection angle in the upper block area is 0~5° downward, towards the middle of the pile, thus ensuring that the flame in the center of the upper nozzle heats the main body of the pile.

The flame injection angle in the lower block area is 10~15° downward and aimed at the root of the pile to ensure that the lower part of the lower nozzle flame covers the aluminum alloy liquid surface as much as possible.

The height difference between the injection position of the upper block area and the injection position of the lower block area is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm. Since the flame has a certain length, a reducing atmosphere zone can be formed at 200~800mm above the liquid surface in the furnace body, and an oxidizing atmosphere zone can be formed at the upper part.

S200: Refining the molten liquid to obtain regenerated aluminum liquid.

In this step, the main purpose of melt refining is to remove impurities and gases in the aluminum liquid to improve the quality and composition uniformity of the aluminum. Impurities in liquid aluminum mainly include harmful elements such as iron, silicon, phosphorus, etc. These elements will have adverse effects on the performance of aluminum. Oxygen, hydrogen and other gases in the aluminum liquid will also affect the performance and quality of the aluminum liquid.

There are two main working principles of aluminum liquid refining: chemical refining and physical refining. Chemical refining mainly uses certain chemical reactions to produce some volatile or dissolved compounds in the aluminum liquid, thereby removing harmful elements and gases. Commonly used methods include chlorination refining, oxidation refining, carbonization refining, etc. Physical refining mainly uses some physical principles or technical means, such as stirring or bubble impact to volatilize or dissolve compounds, and then exhausting the gas through vacuum suction to achieve the purpose of refining.

That is, in this application, the recycled aluminum material is smelted in the temperature range of 580 to 680°C by generating oxidation and reduction atmosphere zones above and below the smelting chamber; on the one hand, the oxidation atmosphere is used to quickly increase the furnace temperature, and the low-temperature injection flame tongue and The high-temperature flue gas can easily melt the surface material pile blocks of the material pile and drill into the inside of the aluminum material pile to achieve melting treatment, reduce the temperature difference between the inside and outside of the scrap aluminum material pile, try to maintain a constant temperature environment, and improve the melting efficiency; on the other hand, through the lower part of the material pile, Combustion in reducing atmosphere reduces burning loss of aluminum liquid and alloy. Using the above combined technology, the time from feeding to aluminum ingot casting can be controlled to about 3 hours, which is 2 hours shorter than the time used by traditional smelting technology, which greatly improves the production efficiency of recycled aluminum ingots. The technology of the present invention can increase the output Increase by more than 50%, reduce burnout rate by 50%, reduce fuel consumption by more than 10%, and reduce flue gas emission treatment load by 60%.

If the smelting furnace is used for primary smelting, the melt containing aluminum will not be included in the smelting furnace. It is similar to the situation where the melt is included in the smelting furnace. Therefore, the flame injection angle, injection position and height difference of the injection position in each area can also be set as a reference. The beneficial effects are also similar and will not be described again.

The above-mentioned smelting method of recycled aluminum smelts the aluminum raw material to be recycled in the temperature range of 580 to 680°C. On the one hand, the oxidizing atmosphere is used to quickly increase the furnace temperature, causing the aluminum raw materials to quickly melt and improve the smelting efficiency. On the other hand, the lower part of the aluminum raw material is burned in the reducing atmosphere to reduce the burning loss of the aluminum liquid and alloy. Using the above-mentioned smelting method of recycled aluminum can not only improve the production efficiency of recycled aluminum, but also have a lower burning loss rate.

In some embodiments, the step of smelting the aluminum raw material to be regenerated at 580-680°C for 75-125 minutes includes:

Within 10-25 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 580-600°C.

Raise the temperature to 650-680°C, keep it for 25-50 minutes, and proceed to the second stage of melting.

Adjust the temperature to 580-630°C, maintain melting for 40-50 minutes, and proceed to the third stage of melting.

That is, the smelting process is realized by regulating the flame spray temperature of the flame nozzles on both sides of the furnace that are aligned with the material pile. Within a smelting cycle, the low-temperature flame spray process is carried out at a temperature of 580-600°C within the first 10-25 minutes (the first stage Smelting), soften the aluminum alloy at low temperature, and then quickly raise the temperature to 650-680℃ (second stage smelting) to speed up the smelting of the aluminum pile. After running for 25-50 minutes, it is finally controlled at 580-630℃ and continues smelting for 40- 50min (third stage smelting).

In some embodiments, during the first stage smelting, the second stage smelting and the third stage smelting, the melt is stirred for 2 to 8 times. This method is beneficial to promote melting.

In some embodiments, the oxidizing atmosphere fire is performed under the condition that the ratio of natural gas to combustion air is less than 1:2. Preferably, the ratio of the oxidizing atmosphere to natural gas and combustion air is 1:3. Of course, natural gas can also be replaced with combustion oil or coal gas, and the ratio requirements for combustion air are similar.

Reducing atmosphere flamethrowing is a combustion flamethrowing condition where the ratio of natural gas to combustion air is greater than 1:2. Preferably, the ratio of the reducing atmosphere to natural gas and combustion air is 1:1.5. Of course, natural gas can also be replaced with combustion oil or coal gas, and the ratio requirements for combustion air are similar.

In some embodiments, the melting temperature in the first stage is increased to 650-680°C at a rate of 5-10°C/min.

In some embodiments, referring to Figure 1, before the aluminum raw material to be regenerated is smelted, it also includes:

The aluminum raw material to be regenerated is passed through the heating furnace wall at 500-600°C for reflection baking;

Continue to directly grill the aluminum raw material to be regenerated at 450-550°C with a long flame (exceeding the core of the stockpile), and introduce air heated by waste heat to blow away the separated hardened paint film or hardened grease.

When the aluminum raw material to be regenerated has a large amount of paint film or grease, it needs to be depainted and degreased before smelting.

The operation process of paint removal and degreasing technology is to arrange flame nozzles on the top of both sides of the processing chamber to spray fire on the furnace wall and scrap aluminum products/pieces, so that the flame tongue covers 50% of the furnace wall surface, and the flame tongue passes through the furnace wall Reflective heat transfer transfers and bakes the surrounding and surface temperature of the aluminum pile, and the furnace temperature is 500-600°C. In the low-temperature spray paint removal, the combustion flame nozzle is facing the scrap aluminum block, using high-proportion flux air, using low-temperature direct barbecue, the furnace temperature is 450-550°C; at the same time, large-flux air will separate the hardened paint from the surface The film or hardened grease is blown to the collector below the treatment chamber, and 80% of the surface paint and grease is removed through high-temperature reflection baking for 10-15 minutes and low-temperature grilling for 15-25 minutes.

Among related technologies, the relatively economical method of removing organic coatings and grease on the surface of recycled aluminum by high-temperature combustion will produce a large amount of harmful wastes such as dioxins, as well as a large amount of VOCs emissions and environmental pollution.

In some embodiments, the duration of reflective baking is 10-15 minutes. After reflection baking for 10-15 minutes, direct grilling is performed. The duration of direct grilling is 15-25 minutes.

In some embodiments, the air flow rate is 10~20 Nm³/h, and the paint stripping chamber forms a slight positive pressure of 5~12Pa. That is, the chamber for stripping paint and degreasing has a certain slight positive pressure, which is conducive to discharging the hardened paint film or hardened grease.

In some embodiments, the step of refining the melt includes:

In some embodiments, the step of smelting the aluminum raw material to be regenerated occurs in a smelting furnace, and the step of refining the molten liquid occurs in a refining furnace.

After the molten liquid in the smelting furnace is transferred to the refining furnace, the smelting furnace is stripped of iron, slag, and cleaned, and then enters the next smelting cycle.

Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform iron removal, slag removal, and furnace cleaning on the upper smelting furnace after the aluminum liquid has been transferred , and then enter the next smelting cycle.

A heat exchanger is installed on the main exhaust gas channel on the side of the three furnace chambers of depainting, degreasing, smelting and refining to heat exchange and heat the compressed air participating in combustion to improve the utilization level of waste heat. A dust collector is installed at the rear end of the exhaust channel. and environmental protection equipment such as denitrification and desulfurization.

The specific technical solutions of the present application will be described below with reference to specific examples.

Example

1) Remove paint and grease:

The same type of products or fragments with similar component content are sent to the depainting and degreasing chamber (also called high-temperature pretreatment l) in batches through rollers or conveyor chains for high-temperature baking, depainting and degreasing.

Reflection baking is performed at an oven temperature of 550°C for 15 minutes, and when the reflection baking progresses to 10 minutes, low-temperature direct grilling is turned on, with the oven temperature being 500°C and the duration being 15 minutes. During the low-temperature direct grilling process, air is introduced at a flow rate of 20 Nm³/h to blow the hardened paint film or hardened grease off the surface to the collector below the treatment chamber.

2) Rough smelting: Put the above-mentioned depainted and degreased aluminum raw materials into the smelting furnace (main chamber), and use the smelting technology combining atmosphere zoned low-temperature flame spray to smelt the recycled aluminum;

Within 10 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 590-600°C.

Raise the temperature to 670-680°C, keep it for 25 minutes, and proceed to the second stage of melting.

Adjust the temperature to 620-630°C, maintain melting for 40 minutes, and proceed to the third stage of melting.

During the entire rough refining process, the upper block area is maintained to be burned and melted by oxidizing atmosphere, and the ratio of natural gas to combustion air is greater than 1:2. Keep the lower reducing atmosphere burning, and the ratio of natural gas and combustion air is less than 1:2. Add materials step by step during the melting process and stir the melt steadily 2-8 times. Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

3) Refining: Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform scraping and scraping of the upper smelting furnace after the aluminum liquid has been transferred. slag, clear the furnace, and then enter the next smelting cycle.

The entire rough refining process lasts 75 minutes and the burn loss is 1.6%.

Example

1) Remove paint and grease:

The same type of products or fragments with similar component content are sent to the depainting and degreasing chamber (also called high-temperature pretreatment l) in batches through rollers or conveyor chains for high-temperature baking, depainting and degreasing.

Reflection baking is performed at an oven temperature of 500°C for 20 minutes, and when the reflection baking progresses to 15 minutes, low-temperature direct grilling is turned on, with the oven temperature being 450°C and the duration being 25 minutes. During the low-temperature direct grilling process, air is introduced at a flow rate of 15Nm³/h to blow the hardened paint film or hardened grease off the surface to the collector below the treatment chamber.

2) Rough smelting: Put the above-mentioned depainted and degreased aluminum raw materials into the smelting furnace (main chamber), and use the smelting technology combining atmosphere zoned low-temperature flame spray to smelt the recycled aluminum;

Within 25 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 580-590°C.

Raise the temperature to 650-660°C, keep it for 50 minutes, and proceed to the second stage of melting.

Adjust the temperature to 580-590°C, maintain melting for 50 minutes, and proceed to the third stage of melting.

During the entire rough refining process, the upper block area is maintained to be burned and melted by oxidizing atmosphere, and the ratio of natural gas to combustion air is greater than 1:2. Keep the lower reducing atmosphere burning, and the ratio of natural gas and combustion air is less than 1:2. Add materials step by step during the melting process and stir the melt steadily 2-8 times. Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

3) Refining: Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform scraping and scraping of the upper smelting furnace after the aluminum liquid has been transferred. slag, clear the furnace, and then enter the next smelting cycle.

The entire rough refining process lasts 125 minutes and the burning loss is 1.7%.

Example

1) Remove paint and grease:

The same type of products or fragments with similar component content are sent to the depainting and degreasing chamber (also called high-temperature pretreatment l) in batches through rollers or conveyor chains for high-temperature baking, depainting and degreasing.

Reflection baking is performed at an oven temperature of 500°C for 25 minutes, and when the reflection baking progresses to 12 minutes, low-temperature direct grilling is turned on, with the oven temperature being 500°C and the duration being 20 minutes. During the low-temperature direct grilling process, air is introduced at a flow rate of 15 Nm³/h to blow the hardened paint film or hardened grease off the surface to the collector below the treatment chamber.

2) Rough smelting: Put the above-mentioned depainted and degreased aluminum raw materials into the smelting furnace (main chamber), and use the smelting technology combining atmosphere zoned low-temperature flame spray to smelt the recycled aluminum;

Within 15 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 590-600°C.

Raise the temperature to 660-670°C, keep it for 40 minutes, and proceed to the second stage of melting.

Adjust the temperature to 600-610°C, maintain melting for 45 minutes, and proceed to the third stage of melting.

During the entire rough refining process, the upper block area is maintained to be burned and melted by oxidizing atmosphere, and the ratio of natural gas to combustion air is greater than 1:2. Keep the lower reducing atmosphere burning, and the ratio of natural gas and combustion air is less than 1:2. Add materials step by step during the melting process and stir the melt steadily 2-8 times. Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

3) Refining: Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform scraping and scraping of the upper smelting furnace after the aluminum liquid has been transferred. slag, clear the furnace, and then enter the next smelting cycle.

The duration of the entire rough refining process is 100 minutes, and the burning loss is <1.5%.

Example

1) Remove paint and grease:

The same type of products or fragments with similar component content are sent to the depainting and degreasing chamber (also called high-temperature pretreatment l) in batches through rollers or conveyor chains for high-temperature baking, depainting and degreasing.

Reflection baking was performed at an oven temperature of 550°C for 22 minutes, and when the reflection baking progressed to 18 minutes, low-temperature direct grilling was turned on, with the oven temperature being 530°C and a duration of 18 minutes. During the low-temperature direct grilling process, air is introduced at a flow rate of 16 Nm³/h to blow the hardened paint film or hardened grease off the surface to the collector below the treatment chamber.

2) Rough smelting: Put the above-mentioned depainted and degreased aluminum raw materials into the smelting furnace (main chamber), and use the smelting technology combining atmosphere zoned low-temperature flame spray to smelt the recycled aluminum;

Within 20 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 590-600°C.

Raise the temperature to 670-680°C, keep it for 25 minutes, and proceed to the second stage of melting.

Adjust the temperature to 620-630°C, maintain melting for 40 minutes, and proceed to the third stage of melting.

During the entire rough refining process, the upper block area is maintained to be burned and melted by oxidizing atmosphere, and the ratio of natural gas to combustion air is greater than 1:2. Keep the lower reducing atmosphere burning, and the ratio of natural gas and combustion air is less than 1:2. Add materials step by step during the melting process and stir the melt steadily 2-8 times. Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

3) Refining: Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform scraping and scraping of the upper smelting furnace after the aluminum liquid has been transferred. slag, clear the furnace, and then enter the next smelting cycle.

The entire rough refining process lasts 85 minutes, and the burning loss is 1.6%.

Example

1) Remove paint and grease:

The same type of products or fragments with similar component content are sent to the depainting and degreasing chamber (also called high-temperature pretreatment l) in batches through rollers or conveyor chains for high-temperature baking, depainting and degreasing.

Reflection baking is performed at an oven temperature of 550°C for 20 minutes, and when the reflection baking progresses to 15 minutes, low-temperature direct grilling is turned on, with the oven temperature being 500°C and the duration being 20 minutes. During the low-temperature direct grilling process, air is introduced at a flow rate of 18 Nm³/h to blow the hardened paint film or hardened grease off the surface to the collector below the treatment chamber.

2) Rough smelting: Put the above-mentioned depainted and degreased aluminum raw materials into the smelting furnace (main chamber), and use the smelting technology combining atmosphere zoned low-temperature flame spray to smelt the recycled aluminum.

Within 15 minutes after the aluminum raw materials are added, the first stage of melting is carried out at a temperature of 590-600°C.

Raise the temperature to 650-660°C, keep it for 35 minutes, and proceed to the second stage of melting.

Adjust the temperature to 580-590°C, maintain melting for 50 minutes, and proceed to the third stage of melting.

During the entire rough refining process, the upper block area is maintained to be burned and melted by oxidizing atmosphere, and the ratio of natural gas to combustion air is greater than 1:2. Keep the lower reducing atmosphere burning, and the ratio of natural gas and combustion air is less than 1:2. Add materials step by step during the melting process and stir the melt steadily 2-8 times. Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

3) Refining: Transfer 1/3 to 1/2 of the molten liquid in the above-mentioned smelting furnace to the lower refining furnace through the lower chute within 10-15 minutes for refining, and perform scraping and scraping of the upper smelting furnace after the aluminum liquid has been transferred. slag, clear the furnace, and then enter the next smelting cycle.

In this embodiment, the duration of the entire rough refining process is 100 minutes, and the burning loss is 1.8%.

Comparative example 1

The difference from Example 5 is that both the upper block area and the lower block area are in an oxidizing atmosphere during the entire roughing process. The rest is the same as in Embodiment 5. In this embodiment, the duration of the entire rough refining process is 100 minutes, and the burning loss is 3.0%.

Comparative example 2

The difference from Example 5 is that in the rough refining step, the first stage smelting is performed at a temperature of 590-600°C within 15 minutes after the aluminum raw material is added.

Raise the temperature to 840-850°C, keep it for 35 minutes, and proceed to the second stage of melting.

Adjust the temperature to 840-850°C, maintain melting for 50 minutes, and proceed to the third stage of melting.

Among them, the height difference between the setting position of the upper nozzle and the setting position of the lower nozzle is 500~800mm. The distance between the lower nozzle and the initial aluminum liquid level is 400~800mm.

The rest is the same as in Embodiment 5. In this embodiment, the duration of the entire rough refining process is 100 minutes, and the burning loss is 3.5%.

Comparing the above examples and comparative examples proves that the recycled aluminum smelting method of the present application can not only improve the production efficiency of recycled aluminum, but also have a lower burning loss rate.

Among the above technical solutions of the present invention, the above are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. Under the technical concept of the present invention, equivalent structural transformations can be made using the contents of the description and drawings of the present invention. , or direct/indirect application in other related technical fields are included in the scope of patent protection of the present invention.

Claims (8)

1. The smelting method of the regenerated aluminum is characterized by comprising the following steps of:

smelting an aluminum raw material to be regenerated at 580-680 ℃ for 75-125min to obtain a molten liquid; in the smelting process, the upper area of the aluminum raw material is positioned in the range of oxidizing atmosphere flaming, and the lower area of the aluminum raw material is positioned in the range of reducing atmosphere flaming; the oxidative atmosphere flaming is carried out under the condition that the ratio of natural gas to combustion-supporting air is less than 1 to 2; the reducing atmosphere flaming is carried out under the condition that the ratio of natural gas to combustion-supporting air is more than 1 to 2; the height difference between the spraying position of the oxidizing atmosphere flame spraying and the spraying position of the reducing atmosphere flame spraying is 500-800 mm; the spraying position of the reducing atmosphere flame spraying is 400-800 mm away from the initial aluminum liquid level;

refining the molten liquid to obtain a regenerated aluminum liquid;

the step of smelting the aluminum raw material to be regenerated at 580-680 ℃ for 75-125min comprises the following steps:

smelting in the first stage at 580-600 deg.c within 10-25min after adding aluminum material;

heating to 650-680 ℃, maintaining for 25-50min, and smelting in the second stage;

regulating the temperature to 580-630 ℃, keeping smelting for 40-50min, and carrying out third-stage smelting.

2. The method for smelting secondary aluminum according to claim 1, wherein the molten liquid is stirred for 2 to 8 times in the first-stage smelting, the second-stage smelting and the third-stage smelting.

3. The method for smelting secondary aluminum according to claim 1, wherein the smelting temperature in the first stage is raised to 650-680 ℃ at a rate of 5-10 ℃/min.

4. The method for smelting recycled aluminum according to claim 1, further comprising, before smelting the aluminum raw material to be recycled:

the aluminum raw material to be regenerated is passed through a furnace wall of a heater at 500-600 ℃ for reflection baking;

and continuously roasting the aluminum raw material to be regenerated under the condition of 450-550 ℃ with long flame, and blowing off the detached hardening paint film or hardening grease by introducing air heated by waste heat.

5. The method for smelting secondary aluminum according to claim 4, wherein the duration of the reflective baking is 15-25 min;

and after the reflective baking is carried out for 10-15min, carrying out direct baking, wherein the duration of the direct baking is 15-25 min.

6. The method for smelting secondary aluminum according to claim 4, wherein the flow rate of the air is 10-20 Nm/h.

7. The method of smelting secondary aluminum as defined in claim 4 wherein the step of refining the molten metal includes:

adding 0.20% of refining agent at 680-720 ℃ of the aluminum liquid in the furnace, refining for 10-15min, lifting wave height during refining between 30-80 mm, and standing for 8-12 min for slag skimming after refining.

8. The method for smelting secondary aluminum according to any one of claims 1 to 7, wherein,

the step of smelting the aluminum raw material to be regenerated occurs in a smelting furnace, and the step of refining the molten liquid occurs in a refining furnace;

after the molten liquid in the smelting furnace is transferred to the refining furnace, iron skimming, slag skimming and furnace cleaning are carried out on the smelting furnace, and then the next smelting period is carried out.