Process method for removing excessive zinc element in aluminum scrap melt

Abstract

The invention discloses a process method for removing excessive zinc elements in aluminum scrap melt. The process method comprises the following steps that an aluminum alloy raw material is heated to be molten; spraying flux powder into the aluminum alloy melt by taking inert gas as a carrier; uniformly spreading the covering agent on the surface of the aluminum alloy melt, heating and standing; slagging-off treatment is conducted, and the aluminum alloy melt is poured into a casting mold; wherein the flux is prepared from CaCl2, MnCl2, a cosolvent and sulfur powder; the covering agent comprises alumina powder and activated carbon. The elements in the flux react with the zinc element in the aluminum alloy, are converted into compounds, enter the slag and are separated from the aluminum alloy melt, so that the content of the zinc element in the aluminum alloy is reduced by 20-30%.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy recovery and relates to a process for removing excess zinc elements from waste aluminum melt. Background Art

[0002] With the continuous improvement of aluminum alloy production technology and the continuous expansion of the application field of aluminum alloy products, the market demand for aluminum alloy is increasing. The scarcity of aluminum resources has made the recycling and reuse of scrap aluminum more and more concerned. However, the source of scrap aluminum is complex and the pollution is heavy. The impurity elements in it will have different degrees of influence on the performance of the material. The zinc element in scrap aluminum is a common alloying element in aluminum alloys. It is more active than other elements in cast aluminum, and the solubility of zinc in aluminum is very large. The limit solubility at 277°C is 32.4%. Therefore, cast aluminum-zinc alloy is also a commonly used aluminum alloy series, accounting for a relatively large proportion of scrap aluminum raw materials. Because the increase in zinc content will aggravate the hydrogen absorption tendency of the aluminum alloy production process, and at the same time, it will form a large number of brittle compounds with other elements, there is a tendency of stress corrosion cracking, which makes the production of aluminum alloy difficult and the quality is difficult to guarantee. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a process for removing excess zinc from waste aluminum melts, so as to solve the problem that the production of aluminum alloys is difficult and the quality is difficult to ensure due to the excessive zinc content in the waste aluminum melts.

[0004] Technical solution: A process for removing excess zinc from aluminum melt of waste aluminum of the present invention comprises the following steps:

[0005] (1) heating the aluminum alloy raw material until it is molten;

[0006] (2) Spraying flux powder into aluminum alloy melt using inert gas as a carrier;

[0007] (3) Spread the covering agent evenly on the surface of the aluminum alloy melt, heat it up and let it stand;

[0008] (4) Slag removal, pouring the aluminum alloy melt into the casting mold;

[0009] Wherein, the flux includes: CaCl2, MnCl2, co-solvent, sulfur powder; the covering agent includes alumina powder and activated carbon.

[0010] Furthermore, the mass components of the flux are: CaCl2 20-40%, MnCl2 20-40%, solvent 10-30%, and sulfur powder 10-30%.

[0011] Furthermore, the covering agent also includes CaCl2, and the mass components of the covering agent are: 30-50% alumina powder, 10-30% activated carbon, and 20-40% CaCl2.

[0012] Furthermore, the co-solvent is borax.

[0013] Furthermore, in step (2), the amount of flux injected is 0.1-0.5% of the mass of the aluminum alloy melt.

[0014] Furthermore, the amount of covering agent added in step (3) is 0.05-0.3% of the mass of the aluminum alloy melt.

[0015] Furthermore, the heating temperature of step (1) is heated to 720-750°C.

[0016] Furthermore, the inert gas in step (2) is Ar gas or N2.

[0017] Furthermore, the heating temperature in step (3) is 750-800°C.

[0018] Furthermore, the standing time of step (3) is 10-20 minutes.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. By adding a flux with a certain composition into the aluminum alloy melt, the present invention utilizes the elements in the flux to react with the zinc element in the aluminum alloy, converting it into a compound and entering into the slag to be separated from the aluminum alloy melt, thereby reducing the zinc content in the aluminum alloy by 20-30%.

[0020] 2. The present invention forms alkaline slag by adding a covering agent, which is beneficial to remove excess sulfur and achieve the effect of purifying aluminum liquid. At the same time, the activated carbon in the covering agent can also adsorb fine powdery compounds. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with different embodiments.

[0022] A process for removing excess zinc from aluminum melt of waste aluminum of the present invention comprises the following steps:

[0023] (1) heating the aluminum alloy raw material to 720-750° C. to melt the aluminum alloy to obtain an aluminum alloy melt;

[0024] (2) using inert gas Ar or N2 as a carrier to spray flux powder into the aluminum alloy melt, the amount of flux sprayed is 0.1-0.5% of the mass of the aluminum alloy melt;

[0025] (3) Spreading the covering agent evenly on the surface of the aluminum alloy melt, heating to 750-800° C. and leaving it to stand for 10-20 minutes, wherein the amount of the covering agent added is 0.05-0.3% of the mass of the aluminum alloy melt;

[0026] (4) Slag removal, followed by pouring the aluminum alloy melt into a casting mold.

[0027] The mass percentage of the flux is: CaCl2 20-40%, MnCl2 20-40%, solvent 10-30%, sulfur powder 10-30%. The addition of CaCl2 and MnCl2 can mainly form AlCl3, which plays the role of scum. The reaction formula is: 3MnCl2(s)+2Al(l)=3Mn(s)+2AlCl3↑. The reaction between sulfur (S) and zinc (Zn) can be carried out at a higher temperature (about 200°C) to generate zinc sulfide (ZnS) powder, which is separated from the liquid. The reaction formula is: S+Zn→ZnS.

[0028] In a specific embodiment, borax is selected as the co-solvent. Borax is used as the co-solvent mainly because of its low melting point and the possibility of reacting with Zn in the melt to form zinc borate powder and separate from the liquid.

[0029] The mass percentage of the covering agent is: 30-50% alumina powder, 10-30% activated carbon, and 20-40% CaCl2. The main function of the covering agent is to form alkaline slag, which is conducive to removing excess sulfur elements and purifying aluminum liquid. The main function of activated carbon is to absorb fine powdery compounds.

[0030] Example 1

[0031] (1) heating the aluminum alloy raw material to 720-750° C. to melt the aluminum alloy to obtain an aluminum alloy melt;

[0032] (2) using inert gas Ar or N2 as a carrier, spraying flux powder into the aluminum alloy melt, the mass composition of the solvent is: CaCl2 20%, MnCl2 40%, sulfur powder 15%, borax 25%; the amount of flux sprayed is 0.3% of the mass of the aluminum alloy melt;

[0033] (3) Spreading the covering agent evenly on the surface of the aluminum alloy melt, heating it to 750-800°C and letting it stand for 20 minutes; the mass composition of the covering agent is: 50% alumina powder and 50% activated carbon; the amount of the covering agent added is 0.2% of the mass of the aluminum alloy melt;

[0034] (4) Slag removal, followed by pouring the aluminum alloy melt into a casting mold.

[0035] The zinc content in the aluminum alloy solution in step (1) and step (3) was detected respectively, and it was found that the zinc content in this embodiment was reduced from 0.30% to 0.24%.

[0036] Example 2

[0037] (1) heating the aluminum alloy raw material to 720-750° C. to melt the aluminum alloy to obtain an aluminum alloy melt;

[0038] (2) using inert gas Ar or N2 as a carrier, spraying flux powder into the aluminum alloy melt, the mass composition of the solvent is: CaCl2 30%, MnCl2 30%, sulfur powder 30%, borax 10%; the amount of flux sprayed is 0.3% of the mass of the aluminum alloy melt;

[0039] (3) Spread the covering agent evenly on the surface of the aluminum alloy melt, heat it to 750-800°C and let it stand for 15 minutes; the mass composition of the covering agent is: 50% alumina powder, 30% activated carbon, and 20% CaCl2; the amount of the covering agent added is 0.15% of the mass of the aluminum alloy melt;

[0040] (4) Slag removal, followed by pouring the aluminum alloy melt into a casting mold.

[0041] The zinc content in the aluminum alloy solution in step (1) and step (3) was detected respectively, and it was found that the zinc content in this embodiment was reduced from 0.28% to 0.20%.

[0042] Example 3

[0043] (1) heating the aluminum alloy raw material to 720-750° C. to melt the aluminum alloy to obtain an aluminum alloy melt;

[0044] (2) using inert gas Ar or N2 as a carrier, spraying flux powder into the aluminum alloy melt, the mass composition of the solvent is: CaCl2 40%, MnCl2 30%, sulfur powder 10%, borax 20%; the amount of flux sprayed is 0.2% of the mass of the aluminum alloy melt;

[0045] (3) Spreading the covering agent evenly on the surface of the aluminum alloy melt, heating to 750-800°C and leaving it to stand for 10 minutes; the mass composition of the covering agent is: 50% alumina powder, 50% activated carbon; the amount of the covering agent added is 0.1% of the mass of the aluminum alloy melt;

[0046] (4) Slag removal, followed by pouring the aluminum alloy melt into a casting mold.

[0047] The zinc content in the aluminum alloy solution in step (1) and step (3) was detected respectively, and it was found that the zinc content in this embodiment was reduced from 0.25% to 0.20%.

[0048] Comparative Example

[0049] (1) heating the aluminum alloy raw material to 720-750° C. to melt the aluminum alloy to obtain an aluminum alloy melt;

[0050] (2) using inert gas Ar or N2 as a carrier, spraying flux powder into the aluminum alloy melt, the mass composition of the solvent is: CaCl2 40%, MnCl2 30%, borax 30%; the amount of flux sprayed is 0.3% of the mass of the aluminum alloy melt;

[0051] (3) Spreading the covering agent evenly on the surface of the aluminum alloy melt, heating it to 750-800°C and letting it stand for 20 minutes; the mass composition of the covering agent is: 50% alumina powder and 50% activated carbon; the amount of the covering agent added is 0.2% of the mass of the aluminum alloy melt;

[0052] (4) Slag removal, followed by pouring the aluminum alloy melt into a casting mold.

[0053] The zinc content in the aluminum alloy solution in step (1) and step (3) was detected respectively, and the zinc content in the comparative example was reduced from 0.30% to 0.28%. The reduced addition of sulfur powder in the solvent of the comparative example did not show a good zinc removal effect as a whole.

Claims

1. A process for removing excess zinc from aluminum melts, characterized in that: The following steps are involved: (1) heating the aluminum alloy raw material until it is melted; (2) Spraying flux powder into aluminum alloy melt using inert gas as a carrier; (3) Spread the covering agent evenly on the surface of the aluminum alloy melt, heat it up and let it stand; (4) Slag removal, pouring the aluminum alloy melt into the casting mold; The flux includes CaCl2, MnCl2, a solvent, and sulfur powder; and the covering agent includes alumina powder and activated carbon.

2. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The flux comprises the following components by mass: CaCl2 20-40%, MnCl2 20-40%, co-solvent 10-30%, and sulfur powder 10-30%.

3. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The covering agent further comprises CaCl2, and the mass components of the covering agent are: 30-50% alumina powder, 10-30% activated carbon, and 20-40% CaCl2.

4. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1 or 2, characterized in that: The cosolvent is borax.

5. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The amount of flux injected in step (2) is 0.1-0.5% of the mass of the aluminum alloy melt.

6. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The amount of the covering agent added in step (3) is 0.05-0.3% of the mass of the aluminum alloy melt.

7. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The heating temperature in step (1) is 720-750°C.

8. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The inert gas in step (2) is Ar gas or N2.

9. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The heating temperature in step (3) is 750-800°C.

10. The process for removing excess zinc from aluminum melt by scrap aluminum according to claim 1, characterized in that: The standing time of step (3) is 10-20 minutes.