A method for utilizing waste heat from hot aluminum ash in casting aluminum alloy

Abstract

The present invention relates to the technical field of aluminum ash, and discloses a method for utilizing the waste heat of hot aluminum ash from cast aluminum alloys, comprising the following steps: S1: wetting a ash-cooking agent: adding deionized water to the ash-cooking agent and stirring to mix; S2: simultaneously adding hot aluminum ash and cold aluminum ash into a rotary furnace, rotating and mixing; S3: continuing to add the wetting ash-cooking agent and a heating agent into the rotary furnace, and performing a first-stage rotation; S4: introducing nitrogen into the rotary furnace and adding a covering agent, and performing a second-stage rotation; S5: separating the filter residue and aluminum liquid in the rotary furnace. A ash-cooking agent is also disclosed. The present application shortens the time it takes for the melt to break the oxide film, thereby avoiding the ash-cooking agent from being burned out due to being at high temperature for too long. At the same time, the ash-cooking agent is used to reduce the surface tension of the aluminum, thereby improving the wettability of the aluminum, causing the aluminum droplets to converge and fuse with each other, and improving the separation yield of the aluminum liquid.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum ash, and in particular relates to a method for utilizing waste heat of hot aluminum ash produced by casting aluminum alloy. Background Art

[0002] During the aluminum alloy production process, a large amount of aluminum ash is generated. Since aluminum ash is usually scraped out from high-temperature containers such as holding furnaces and melting furnaces, it usually has a high temperature. If it is not scraped out and recycled in time, the aluminum in the aluminum ash will easily be burned or oxidized, resulting in a waste of resources.

[0003] In the existing technology, sulfur and charcoal powder are usually used as heating components, and sodium nitrate, sodium sulfate, etc. are used as melts to destroy the oxide film to achieve the separation of slag liquid from aluminum ash;

[0004] However, the use of sodium nitrate, sodium sulfate, etc. as a melt for destroying the oxide film requires that the temperature of the aluminum ash is not higher than 600°C, otherwise the melt breaking ability may be reduced. However, the melting point of aluminum is 660°C, so it is easy for the temperature to be insufficient in the later stage, resulting in the remaining aluminum in the aluminum ash being unable to form aluminum liquid, and then unable to be separated from the slag, and the separation and recovery rate of the aluminum liquid cannot be increased; for example, the patent with publication number CN112961992B discloses an aluminum ash frying agent, which discloses a frying agent containing sodium nitrate, sodium sulfate, etc., which requires the temperature of the aluminum ash to be no higher than 600°C.

[0005] In view of the above situation, how to ensure rapid temperature rise so that the melt can destroy the oxide film quickly and efficiently, while ensuring the output of aluminum liquid after slag-liquid separation, is an urgent problem that needs to be solved. Summary of the Invention

[0006] The present application is used to solve the technical problem in the prior art that the oxide film-destroying melt component is easily ineffective at too high a temperature, resulting in poor oxide film breakage effect, and further leading to low aluminum liquid production after slag-liquid separation.

[0007] Therefore, the first object of the present invention is to provide a method for utilizing waste heat of hot aluminum ash from cast aluminum alloy, comprising the following steps:

[0008] S1 Wetting the ash agent: Add deionized water to the ash agent and stir to mix;

[0009] S2 puts hot aluminum ash and cold aluminum ash into the rotary furnace at the same time and rotates to mix them;

[0010] S3 continues to add the wet ash roasting agent and the heating agent into the rotary kiln and performs the first stage rotation;

[0011] S4: nitrogen is introduced into the rotary kiln and a covering agent is added to perform the second stage of rotation;

[0012] S5 separates the filter residue and aluminum liquid in the rotary furnace.

[0013] The technical mechanism is:

[0014] (1) Deionized water is used to pre-dissolve the ash agent, and the ionic bonds of the ash agent substances will be destroyed, thereby reducing the melting point of the ash agent, making it easier for the ash agent to quickly form a melt covering the oxide film layer on the surface of the aluminum liquid after the mixed aluminum ash is added and the oxide film layer is broken, shortening the time for the melt to break the oxide film, and avoiding the ash agent being burned and ineffective due to being at high temperature for too long. At the same time, the use of ash agent can also reduce the tension of the aluminum surface, thereby improving the wettability of aluminum, so that the aluminum droplets converge and merge with each other.

[0015] (2) By adding a humidifying agent and a heating agent to the mixed aluminum ash, it is possible to ensure that a melt is further quickly formed after the addition of the humidifying agent, and the oxide film on the surface of the aluminum liquid is efficiently broken.

[0016] (3) Further adding covering agent to cover and protect the aluminum liquid to prevent the aluminum liquid from being oxidized again, while ensuring the temperature of the rotary furnace in the later stage, so as to facilitate the separation of slag and aluminum liquid.

[0017] The second object of the present invention is to provide a ash roasting agent, characterized in that it comprises the following components in a mass ratio: sodium fluoride: sodium fluorosilicate: chloride salt is 0.2-0.34:0.4:0.45:0.32-0.42.

[0018] The beneficial effects of this application are as follows:

[0019] (1) The present application first uses deionized water to pre-dissolve the ash agent, and then the ionic bonds of the ash agent substance will be destroyed, thereby reducing the melting point of the ash agent, making it easier for the ash agent to quickly form a melt covering the oxide film layer on the surface of the aluminum liquid after the mixed aluminum ash is added and the oxide film layer is broken, shortening the time for the melt to break the oxide film, and avoiding the ash agent being burned and ineffective due to being at high temperature for too long. At the same time, the use of the ash agent can also reduce the tension of the aluminum surface, thereby improving the wettability of the aluminum, causing the aluminum droplets to converge and merge with each other, and improving the separation yield of the aluminum liquid.

[0020] (3) The present application can fully utilize the waste heat of hot aluminum ash to preheat the cold aluminum ash. In addition, the use of a covering agent with a heat-insulating effect can insulate the later rotary kiln, thereby avoiding the continued addition of heating components and saving resources. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0022] First, the present invention provides a method for utilizing waste heat from hot aluminum ash from cast aluminum alloy, comprising the following steps:

[0023] S1 Wetting the ash agent: Add deionized water to the ash agent and stir to mix;

[0024] S2 puts hot aluminum ash and cold aluminum ash into the rotary furnace at the same time and rotates to mix them;

[0025] S3 continues to add the wet ash roasting agent and the heating agent into the rotary kiln and performs the first stage rotation;

[0026] S4: nitrogen is introduced into the rotary kiln and a covering agent is added to perform the second stage of rotation;

[0027] S5 separates the filter residue and aluminum liquid in the rotary furnace.

[0028] In the present invention, the mass ratio of hot aluminum ash, cold aluminum ash, ash roasting agent, deionized water and heating agent is 18-20:8-12:1.5-2.5:1.2-2:1.5-2.5.

[0029] In the present invention, the temperature-raising agent comprises calcium oxide and charcoal powder.

[0030] The use of calcium oxide can achieve a rapid and short-term temperature increase, quickly ignite charcoal powder, and promote rapid combustion and temperature increase of charcoal powder, so as to quickly melt the wet ash roasting agent. Calcium oxide reacts with heat to generate calcium hydroxide, which can form dry, low-viscosity alkaline slag and alkalize the remaining acidic slag, thereby facilitating the separation of aluminum liquid and slag.

[0031] In the present invention, the mass ratio of calcium oxide to charcoal powder is 3.5-4:10-12.

[0032] In the present invention, the covering agent includes graphite powder, sodium chloride, and aluminum trifluoride.

[0033] By using graphite powder to keep the heat in place, sodium chloride to protect the surface, and aluminum trifluoride to lower the melting point of the aluminum liquid, it is ensured that the aluminum liquid in the rotary furnace remains liquid until slagging.

[0034] In the present invention, the mass ratio of graphite powder, sodium chloride and aluminum trifluoride is 2.8-4.2:1-2:0.8-1.5.

[0035] In the present invention, the covering agent accounts for 10-20% of the total mass of the cold aluminum ash and the hot aluminum ash.

[0036] In the present invention, in S2, the stirring speed of the rotary kiln is 1.5 to 2 r / min, and the stirring time is 30 to 60 min.

[0037] In the present invention, in S3, the stirring speed of the first stage rotary kiln is 10-15 r / min, and the stirring time is 20-30 min.

[0038] In the present invention, in S4, the stirring speed of the second stage rotary kiln is 7 to 10 r / min, and the stirring time is 10 to 15 min.

[0039] Second, the present invention provides a ash roasting agent, characterized in that it includes the following components in a mass ratio: sodium fluoride: sodium fluorosilicate: chloride salt is 0.2-0.34:0.4-0.45:0.32-0.42.

[0040] In the present invention, the chloride salt includes at least one of potassium chloride, sodium chloride, and magnesium chloride.

[0041] <Example>

[0042] Example 1

[0043] According to the mass ratio, 1800kg of hot aluminum ash and 800kg of cold aluminum ash are put into the rotary furnace, and the temperature of the rotary furnace is tested to ensure that the temperature is within 500-600°C; the rotary furnace is started and rotated at a speed of 1.5r / min for 30min, and 150kg of ash-cooking agent (sodium fluoride: sodium fluorosilicate: chloride in a mass ratio of 0.2:0.4:0.32) and 120kg of deionized water are mixed and stirred to make the wet ash-cooking agent put into the rotary furnace, and then 150kg of warming agent (calcium oxide: charcoal powder in a mass ratio of 3.5:10) is quickly added. The ash roasting agent is quickly put into the furnace, and the water vapor instantly evaporated by the wet ash roasting agent is used to instantly cremate the heating agent that is immediately put in, thereby quickly raising the temperature in the rotary furnace to 500-600°C, realizing the rapid melting of the ash roasting agent, and then adjusting the speed of the rotary furnace to 10r / min and rotating for 20min; then nitrogen is introduced and 260kg of covering agent (the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 2.8:1:0.8) is added, and the rotary furnace is rotated at 7r / min for 10min, 50-60% of the slag of the rotary furnace is scraped out, and then the aluminum liquid is poured to realize slag-liquid separation.

[0044] Example 2

[0045] The present embodiment differs from the embodiment 1 in that 2000 kg of hot aluminum ash and 1200 kg of cold aluminum ash are put into a rotary furnace, which is started and rotated at a speed of 2 r / min for 60 min; 200 kg of deionized water is used to wet 250 kg of ash-cooking agent (the mass ratio of sodium fluoride: sodium fluorosilicate: chloride is 0.34:0.45:0.42); 250 kg of warming agent (the mass ratio of calcium oxide: charcoal powder is 4:12) is quickly put into the furnace, the rotary furnace speed is adjusted to 15 r / min and rotated for 30 min; 320 kg of covering agent (the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 2.8:1:0.8) is added, and the rotary furnace is rotated at 10 r / min for 15 min.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that the amount of deionized water is 180 kg.

[0048] Example 4

[0049] The difference between this embodiment and embodiment 3 is that the mass ratio of calcium oxide to charcoal powder in 150 kg of the warming agent is 4:10.

[0050] Example 5

[0051] The difference between this embodiment and embodiment 1 is that the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride in the covering agent is 3:1:0.8.

[0052] Example 6

[0053] The difference between this embodiment and embodiment 5 is that the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 3:1:1.

[0054] <Comparative Example>

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that deionized water is not used for humidification and calcium oxide is not included.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 5 is that the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 0:1:0.8.

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 6 is that the mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 3:1:0.

[0061] Comparative Example 4

[0062] The difference between this comparative example and Example 1 is that no ash roasting agent is used.

[0063] Comparative Example 5

[0064] The difference between this comparative example and Example 1 is that no heating agent and ash roasting agent are used.

[0065] The aluminum liquid finally separated from Examples 1-6 and Comparative Examples 1-5 was weighed, and the weighing results are shown in Table 1:

[0066] Table 1

[0067]

[0068]

[0069] From the comparative analysis of Examples 1-6 and Comparative Examples 1-5 in Table 1, it can be seen that the content of the warming agent and the ratio of its components, the wettability of the ash roasting agent, the content of the graphite powder in the covering agent for insulation, and the content of aluminum trifluoride for lowering the melting point of aluminum all have an impact on the amount of aluminum liquid finally separated. Among them, the wettability of the ash roasting agent, the content of the warming agent, and the ratio of its components all have a major impact on the final slag-liquid separation. In addition, the heat release of calcium oxide is used to quickly ignite the charcoal powder, thereby rapidly increasing the temperature in the rotary kiln, causing the ash roasting agent to quickly melt and break the oxide film on the surface of the aluminum liquid, thereby increasing the final yield of separated aluminum liquid.

[0070] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for utilizing waste heat from hot aluminum ash produced by casting aluminum alloy, characterized in that: The process includes the following steps: S1 Wetting the ash-cooking agent: Add deionized water to the ash-cooking agent and stir to mix; S2: put the hot aluminum ash and the cold aluminum ash into the rotary furnace at the same time, and rotate to mix them; S3 continues to add the wet ash roasting agent and the heating agent into the rotary kiln and performs the first stage rotation; S4: nitrogen is introduced into the rotary kiln and a covering agent is added to start the second stage of rotation; S5 separates the slag and aluminum liquid in the rotary furnace; The mass ratio of hot aluminum ash, cold aluminum ash, ash roasting agent, deionized water, and warming agent is 18~20:8~12:1.5~2.5:1.2~2:1.5~2.5; The warming agent includes calcium oxide and charcoal powder; The covering agent in S4 includes graphite powder, sodium chloride, and aluminum trifluoride; The mass ratio of graphite powder, sodium chloride, and aluminum trifluoride is 2.8~4.2:1~2:0.8~1.

5.

2. The method for utilizing waste heat of hot aluminum ash from cast aluminum alloy according to claim 1, characterized in that: The mass ratio of calcium oxide to charcoal powder is 3.5~4:10~12.

3. The method for utilizing waste heat of hot aluminum ash from cast aluminum alloy according to claim 1, characterized in that: The covering agent accounts for 10-20% of the total mass of the cold aluminum ash and the hot aluminum ash.

4. The method for utilizing waste heat of hot aluminum ash from cast aluminum alloy according to claim 1, characterized in that: In S2, the stirring speed of the rotary kiln is 1.5~2r / min, and the stirring time is 30~60min.

5. The method for utilizing waste heat of hot aluminum ash from cast aluminum alloy according to claim 1, characterized in that: The stirring speed of the rotary kiln in the first stage is 10~15r / min, and the stirring time is 20~30min.

6. The method for utilizing waste heat of hot aluminum ash from cast aluminum alloy according to claim 1, characterized in that: The ash-frying agent comprises the following components in terms of mass ratio: sodium fluoride: sodium fluorosilicate: chloride in a ratio of 0.2-0.34:0.4-0.45:0.32-0.42.

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