A method for preparing low-Mg scrap aluminum material

Abstract

The invention belongs to the field of aluminum alloy materials, and provides a method for preparing low-Mg waste aluminum material, wherein aluminum chips are put into a rotary kiln, and hot aluminum ash slag accounting for 50±5% of the weight of the aluminum chips is poured on the aluminum chips; the aluminum ash slag and the aluminum chips are evenly stirred, and during the stirring period, a stirrer is evenly added, and a stirring rake is continuously stirred, and the rotary kiln is tilted every 10-15 minutes, and the liquid aluminum in the aluminum ash slag is poured into a container; until there is no more liquid aluminum in the aluminum ash slag, and the liquid aluminum in the container solidifies to obtain low-Mg waste aluminum material. The ADC12 aluminum chip liquid prepared by the invention has a Mg content of ≤0.03%; the 356 aluminum chip liquid prepared by the invention has a Mg content of ≤0.05%; and can be used as a raw material for low-Mg cast aluminum alloy.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy materials and relates to a method for preparing low-Mg waste aluminum material. Background Art

[0002] With the development of integrated automotive die casting, die castings are becoming larger and thinner. This type of die casting is not suitable for heat treatment, which will cause deformation of the casting and a high scrap rate. In order to adapt to the development of integrated die casting, heat-treatment-free aluminum alloy materials have been born. Combined with the global carbon reduction policy, heat-treatment-free aluminum alloy materials must add a certain amount of scrap aluminum to produce.

[0003] One of the core technologies of heat-treatment-free aluminum alloy materials is to reduce the Mg content and reduce the natural aging effect of Mg2Al phase. Therefore, the Mg content of heat-treatment-free aluminum alloy materials is relatively low, and the Mg content of some materials is less than 0.06%.

[0004] The Mg content (%) in scrap aluminum on the market is shown in Table 1. The main grades of cast aluminum scrap are 356 and ADC12, and the main grades of deformed aluminum scrap are 5XXX, 6XXX, 3XXX, and 1XXX. When producing low-Mg (Mg < 0.06%) heat-treatment-free cast aluminum alloys, 1XXX and 3XXX deformed aluminum scraps are more suitable from the perspective of Mg content alone. However, 1XXX and 3XXX deformed aluminum scraps are generally recycled directly by deformed aluminum alloy manufacturers at a high price, and foundries do not have a recycling price advantage; the Mg element in 356 and ADC12 in cast aluminum scrap is relatively high, and if used directly, the composition does not meet the standard. Chinese patent CN103740948A discloses a method for removing magnesium impurity elements in the regeneration of scrap aluminum. First, a magnesium removal flux is prepared; scrap aluminum is put into a smelting furnace to melt into a scrap aluminum melt, and then a magnesium removal flux is added. After the magnesium removal flux is added, it is allowed to stand to obtain a scrap aluminum melt with the magnesium removal flux added; when the magnesium oxide and / or magnesium compound in the scrap aluminum melt floats to the surface of the scrap aluminum melt, the magnesium oxide and / or magnesium compound are removed by slag removal, and then allowed to stand again, and then poured out of the furnace after standing to obtain a regenerated aluminum alloy with magnesium impurity elements removed from the scrap aluminum. Although the method of adding a magnesium removal agent can reduce the impurity element magnesium in the aluminum melt, it requires additional heating and is costly. Moreover, when the magnesium content of the magnesium removal agent on the market is less than 0.15%, it is difficult to further reduce the Mg content.

[0005] Table 1 Mg content in scrap aluminum on the market (%)

[0006]

[0007] Therefore, there is an urgent need to find a preparation method for treating low-Mg scrap aluminum materials, especially scrap aluminum materials with a Mg content of less than 0.15%, with a low price and high magnesium removal rate. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing low-Mg waste aluminum materials. By using aluminum chips and hot aluminum ash slag as raw materials, adding a ash roasting agent and stirring the reaction, the Mg content in the aluminum chips can be greatly reduced, and the Mg content can be made ≤0.05%, while reducing the production cost of low-Mg cast aluminum alloy materials.

[0009] The technical solution adopted by the present invention to solve the technical problem is:

[0010] The present invention provides a method for preparing low-Mg scrap aluminum material, the steps of which are as follows:

[0011] (1) Put aluminum chips into the rotary kiln, and pour hot aluminum ash slag accounting for 50±5% of the weight of the aluminum chips on the aluminum chips;

[0012] (2) Manually use a forklift to drive a stirring rake to stir the aluminum ash slag and aluminum chips, and evenly add a ash stirrer accounting for 4-5% of the total mass of the aluminum ash slag and aluminum chips during the stirring period;

[0013] (3) The stirring rake stirs continuously and the rotary kiln is tilted every 10-15 minutes to pour the liquid aluminum in the aluminum ash into the container until there is no more liquid aluminum in the aluminum ash. The liquid aluminum in the container solidifies and becomes low-Mg scrap aluminum.

[0014] In the preparation process of the present invention, the ash roasting agent reacts chemically with the aluminum ash slag to release a large amount of heat. The temperature of the aluminum ash slag after combustion reaches about 1000 degrees, which promotes the melting of aluminum chips. Since Mg is flammable, the Mg in the aluminum chips undergoes an oxidation reaction after being heated to generate MgO, thereby reducing the Mg content in the aluminum chips.

[0015] If the temperature of aluminum ash slag is higher than 1200 degrees, cold aluminum ash slag can be added to cool it down. If the temperature of aluminum ash slag is lower than 650 degrees, the amount of ash roasting agent can be increased.

[0016] Furthermore, the hot aluminum slag is scraped out from the aluminum alloy melting furnace with a temperature of 650-800 degrees.

[0017] Furthermore, the aluminum chips are 356 aluminum chips or ADC12 aluminum chips.

[0018] Furthermore, the ash roasting agent includes Na2CO3, Na2SO4, NaNO3, and sodium fluorosilicate, and the mass percentages are respectively: Na2CO3 20%, Na2SO4 25%, NaNO3 20%, and sodium fluorosilicate 25%.

[0019] Furthermore, during the preparation process, the rotary kiln maintains a rotation frequency of 2 to 3 r / min.

[0020] The advantages and positive effects of the present invention are:

[0021] 1. The present invention utilizes the easy oxidation property of Mg to promote the oxidation of Mg element in aluminum chips during the process of heat generated by the reaction of the ash roasting agent and aluminum ash slag, thereby achieving the purpose of reducing the Mg content in aluminum chips; due to the large surface area of ​​the aluminum chips and the stirring of the stirring rake, the contact area between the aluminum chips and the hot aluminum ash slag is more sufficient, and the oxidation reaction is more sufficient, so the Mg content is significantly reduced.

[0022] 2. The ADC12 aluminum chip liquid prepared by the present invention has a Mg content of ≤0.03%; the 356 aluminum chip liquid prepared by the present invention has a Mg content of ≤0.05%; and they can be used as raw materials for low-Mg cast aluminum alloys.

[0023] 3. The low-Mg aluminum chip liquid prepared by the present invention does not need to use fuel, and the fuel cost is reduced by about 150 yuan / ton; if it is used to produce low-Mg cast aluminum alloy products, the raw material cost is reduced by 300 yuan / ton compared with using 3XXX and 1XXX raw materials. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0025] Example 1

[0026] A method for preparing low-Mg scrap aluminum material, the steps are as follows:

[0027] (1) 2.5 tons of ADC12 aluminum chips are put into the rotary kiln using a feeding tool, and hot aluminum ash slag (hot aluminum slag scraped from an aluminum alloy furnace, with a temperature of 755 degrees) accounting for 50±5% of the weight of the aluminum chips is poured on top of the aluminum chips;

[0028] (2) During the preparation process, the rotary kiln was kept spinning at a frequency of 2.5 r / min, and the aluminum ash slag and aluminum chips were stirred manually by a forklift driven stirring rake. During the stirring process, STH-A1 type ash stirrer (purchased from Lizhong Sitong Light Alloy Group Co., Ltd., model STH-A1, the ash stirrer includes Na2CO3, Na2SO4, NaNO3, sodium fluorosilicate, and the mass percentages are: Na2CO3 20%, Na2SO4 25%, NaNO3 20%, sodium fluorosilicate 25%) accounting for 4% of the total weight of the aluminum ash slag and aluminum chips was evenly added manually;

[0029] (3) The stirring rake stirs continuously and the rotary kiln is tilted every 15 minutes to pour the liquid aluminum in the aluminum ash into the container until there is no more liquid aluminum in the aluminum ash. The liquid aluminum in the container solidifies to obtain low-Mg scrap aluminum.

[0030] Example 2

[0031] A method for preparing low-Mg scrap aluminum material, the steps are as follows:

[0032] (1) Put 3 tons of 356 aluminum chips into the rotary kiln using a feeding tool, and pour hot aluminum ash slag (hot aluminum slag scraped from an aluminum alloy furnace, with a temperature of 736 degrees) accounting for 50±5% of the weight of the aluminum chips on top of the aluminum chips;

[0033] (2) During the preparation process, the rotary kiln maintains a rotation frequency of 2.5 r / min, and the aluminum ash slag and aluminum chips are stirred manually by a forklift driven stirring rake. During the stirring process, 5% STH-A1 type ash stirrer is manually added evenly (purchased from Lizhong Sitong Light Alloy Group Co., Ltd., model STH-A1, the ash stirrer includes Na2CO3, Na2SO4, NaNO3, and sodium fluorosilicate, and the mass percentages are: Na2CO3 20%, Na2SO4 25%, NaNO3 20%, and sodium fluorosilicate 25%).

[0034] (3) The stirring rake stirs continuously and the rotary kiln is tilted every 15 minutes to pour the liquid aluminum in the aluminum ash into the container until there is no more liquid aluminum in the aluminum ash. The liquid aluminum in the container solidifies to obtain low-Mg scrap aluminum.

[0035] Comparative Example 1

[0036] A method for preparing low-Mg scrap aluminum material comprises the following steps: putting 2.5 t of ADC12 aluminum chips into a melting furnace by using a feeding tool, heating the aluminum chips to melt, partially oxidizing the Mg into MgO slag during the heating process, and scraping the MgO slag on the surface of the aluminum liquid into a container by using a slag rake, and then solidifying the aluminum liquid to obtain the low-Mg scrap aluminum material.

[0037] Comparative Example 2

[0038] A method for preparing low-Mg scrap aluminum material comprises the following steps: putting 3 tons of 356 aluminum chips into a melting furnace by using a feeding tool, heating the aluminum chips to melt, partially oxidizing the Mg into MgO slag during the heating process, and scraping the MgO slag on the surface of the aluminum liquid into a container by using a slag rake, and solidifying the aluminum liquid to obtain the low-Mg scrap aluminum material.

[0039] Comparative Example 3

[0040] A method for preparing low-Mg scrap aluminum material, the steps are as follows:

[0041] (1) 2.5 tons of ADC12 aluminum chips are put into the melting furnace using a feeding tool and heated to melt into aluminum alloy liquid.

[0042] (2) Put STM-A3 magnesium remover (purchased from Lizhong Sitong Light Alloy Group Co., Ltd., model STM-A3, composition weight percentage: 10-40% potassium fluoroaluminate, 1-25% potassium fluorosilicate, 0-25% aluminum fluoride, 1-40% hexachloroethane, 20-50% copper rice or iron powder or a mixture of copper rice and iron powder) accounting for 1% of the weight of aluminum chips into the refining powder spraying machine. When the temperature of the aluminum alloy liquid is 740 degrees, 99.999% nitrogen gas is introduced into the refining powder spraying machine with a nitrogen pressure of 0.3MPa. The magnesium remover is brought into the aluminum alloy liquid by nitrogen for magnesium removal. The magnesium removal time is 26 minutes.

[0043] (3) Let it stand for 5 minutes and use a slag rake to remove the aluminum slag caused by magnesium removal.

[0044] Comparative Example 4

[0045] A method for preparing low-Mg scrap aluminum material, the steps are as follows:

[0046] (1) 2.5 tons of 356 aluminum chips are put into the melting furnace using a feeding tool and heated to melt into aluminum alloy liquid.

[0047] (2) Put STM-A3 magnesium remover (purchased from Sitong New Materials) accounting for 1% of the weight of aluminum chips into the refining powder spraying machine. When the temperature of the aluminum alloy liquid is 740 degrees, 99.999% nitrogen gas with a nitrogen pressure of 0.3MPa is introduced into the refining powder spraying machine. The magnesium remover is brought into the aluminum alloy liquid by nitrogen for magnesium removal. The magnesium removal time is 26 minutes.

[0048] (3) Let it stand for 5 minutes and use a slag rake to remove the aluminum slag caused by magnesium removal.

[0049] The magnesium content of the low-Mg scrap aluminum materials prepared in Examples 1-2 and Comparative Examples 1-4 was tested, and the results are shown in Table 2.

[0050] Table 2 Statistics of Mg content after aluminum chips treatment

[0051]

[0052] According to the data in Table 2, it can be seen that in Example 1 and Example 2, ADC12 aluminum chips and 356 aluminum chips are respectively fried with hot aluminum ash slag to remove impurity magnesium, and the reduction rate of Mg can reach 90%. This is because the aluminum chips are mixed with aluminum ash, and the aluminum ash is sandwiched in the aluminum chips, so that all surfaces of the aluminum chips can be heated and oxidized, the heating area is large, the Mg element is fully oxidized, and the magnesium reduction is obvious. However, in Comparative Examples 1 and 2, the aluminum chips are heated alone, and the magnesium reduction effect is not ideal. This is because the aluminum slag is not heated, the heating area of ​​the aluminum chips is small, and the reduction rate of Mg is low. In Comparative Examples 3 and Comparative Examples 4, magnesium removal agents are used to remove magnesium, and the magnesium removal efficiency is not as good as that of Examples 1 and 2.

[0053] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing low-Mg scrap aluminum material, characterized in that: Here are the steps: (1) Aluminum chips are put into a rotary kiln, and hot aluminum ash slag accounting for 50±5% of the weight of the aluminum chips is poured on the aluminum chips; the hot aluminum ash slag is scraped out from an aluminum alloy melting furnace, and the temperature is 650-800 degrees; (2) The aluminum ash slag and aluminum chips are uniformly stirred with a stirring rake, and during the stirring period, a ash stirrer accounting for 4-5% of the total mass of the aluminum ash slag and aluminum chips is uniformly added; the ash stirrer includes Na2CO3, Na2SO4, NaNO3, and sodium fluorosilicate, and the mass percentages are: Na2CO3 20%, Na2SO4 25%, NaNO3 20%, and sodium fluorosilicate 25% respectively; (3) The stirring rake is continuously stirred, and the rotary kiln is tilted every 10-15 minutes to pour the liquid aluminum in the aluminum ash into the container until there is no liquid aluminum in the aluminum ash. The liquid aluminum in the container solidifies to obtain low-Mg scrap aluminum material; when ADC12 aluminum chips are used, the Mg content in the obtained low-Mg scrap aluminum material is ≤0.03%; when 356 aluminum chips are used, the Mg content in the obtained low-Mg scrap aluminum material is ≤0.05%.

2. The preparation method according to claim 1, characterized in that: During the preparation process, the rotary kiln maintains a rotation frequency of 2~3 r / min.

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