Method for refining recycled aluminum alloy and removing residual Sr

Abstract

The invention discloses a method for integrating aluminum alloy reclaimed material refining and residual Sr removal, which comprises the following steps of: 1, melting a Sr-containing aluminum alloy reclaimed material in a concentration furnace at the melting temperature of not lower than 700 DEG C, and measuring the initial concentration of Sr in a molten product to obtain corresponding data; 2, according to the data of the initial concentration of Sr in the recycled aluminum, the input proportion of the Sr removal agent for refining is obtained according to the following formula; and thirdly, according to the calculated flux adding amount of the Sr removal agent for refining, the flux of the Sr removal agent for refining is placed in a rotary blowing degassing machine, and in the degassing process, the flux is sprayed to the bottom of the melt obtained in the first step through a graphite spray head of the rotary blowing degassing machine to remove residual Sr, and a refined molten aluminum solution is obtained. According to the method, ZnCl2 is adopted for removing Sr, the melting point of the replaced Zn is low, the replaced Zn can enter an aluminum alloy melt, and the self-strengthening effect of Zn is achieved. And the obtained refining effect is stable and reaches the standard (first grade), and wide application prospects are achieved.

Description

Technical Field

[0001] The invention relates to the field of metal smelting, in particular to a refining technology for aluminum alloys, and in particular to a method for refining aluminum alloy recycled materials and removing residual Sr. Background Art

[0002] Aluminum alloys are widely used in industrial production, especially in the fields of automobile manufacturing, aerospace and construction. In the production process of aluminum alloys, in order to ensure its mechanical properties and other characteristics, refining treatment is often required to remove impurities and control the alloy composition. In the cast aluminum silicon alloy series, some alloys will add Sr to modify the eutectic silicon phase, but the amount of Sr added to different products is different. Therefore, for some grades of aluminum alloy recycling materials, Sr needs to be removed to meet the use standards of raw materials. For example, in the aluminum silicon alloy A380 with a large dosage, in order to achieve a good eutectic silicon phase modification effect, the amount of Sr element will reach 150-250ppm. If this type of waste is recycled to produce hypereutectic aluminum silicon alloy, the residual amount of Sr element needs to be reduced to below 40ppm.

[0003] Traditional aluminum alloy Sr removal mostly adopts dilution Sr removal method, static Sr removal method or single addition of flux to remove Sr method, etc. These methods have problems such as high cost and low efficiency. Therefore, when processing Sr-containing aluminum silicon alloy recycling materials, how to reduce residual Sr efficiently and at low cost has become a key technical problem in the recycling of aluminum alloy resources.

[0004] In Chinese invention patent CN112853146A, MgCl2 is used to remove Sr. However, when removing Sr in this way, it is necessary to stir it, and at the same time, the replaced Mg is easily burned in the aluminum alloy and will be wasted. This process is relatively backward.

[0005] There are also materials that use CuCl2 to remove Sr. The resulting elemental copper has a melting point above 1000°C and cannot enter the aluminum alloy melt within the normal aluminum alloy melting temperature range. The replaced Cu is wasted. At the same time, its replacement effect (metal activity order) is not as good as ZnCl2.

[0006] Therefore, the present invention adopts ZnCl2 to remove Sr. The replaced Zn has a lower melting point and can enter the aluminum alloy melt to play the self-strengthening role of Zn. Summary of the invention

[0007] The purpose of the present invention is to provide a method for refining aluminum alloy recycled materials and removing residual Sr, which can reduce production costs, improve processing efficiency, expand the recycling scope of Sr-containing recycled aluminum silicon alloys, and promote the recycling of aluminum alloy resources.

[0008] In order to achieve the purpose of the present invention, the technical solution adopted is:

[0009] A method for refining aluminum alloy recycled materials and removing residual Sr comprises the following steps:

[0010] The first step is to melt the Sr-containing aluminum alloy recycled material in a centralized furnace, wherein the melting temperature is not less than 700 degrees Celsius, and measure the initial concentration of Sr in the melted product to obtain corresponding data;

[0011] The second step is to obtain the input ratio of the Sr removal agent for refining according to the data of the initial Sr concentration in the recovered aluminum according to the following formula;

[0012] The amount of flux added for refining Sr removal agent (wt.%) = [Sr initial concentration (ppm) - Sr equilibrium concentration (ppm)] / 100ppm × 0.3-0.5%;

[0013] The Sr equilibrium concentration is 30-40ppm;

[0014] The Sr removal agent for refining includes the following components calculated by weight percentage, wherein the sum of each component is 100%:

[0015] NaNO3 0.01%-99.99%;

[0016] C 0.01%-99.99%;

[0017] ZnCl2 0.01%-99.99%;

[0018] Step 3.

[0019] According to the calculated amount of flux added for refining Sr removal agent, the flux of refining Sr removal agent is placed in a rotary degasser. During the degassing process, the flux is sprayed to the bottom of the melt obtained in the first step through the graphite nozzle of the rotary degasser to remove residual Sr and obtain the refined aluminum liquid solution.

[0020] In a preferred embodiment of the present invention, the melting temperature is not less than 745 degrees Celsius.

[0021] In a preferred embodiment of the present invention, the formula is further preferably as follows:

[0022] The amount of flux added for refining Sr removal agent (wt.%) = [Sr initial concentration (ppm) - Sr equilibrium concentration (ppm)] / 100ppm × 0.4%;

[0023] The Sr equilibrium concentration is 35 ppm.

[0024] In a preferred embodiment of the present invention, the rotary blowing refining parameters are as follows:

[0025] Preheat the graphite nozzle to 350-450℃;

[0026] The rotation speed of the rotary nozzle is 150-160r / min;

[0027] The rotary blowing refining time is 15-20 minutes;

[0028] Use industrial argon or industrial nitrogen as the cyclone gas.

[0029] In a preferred embodiment of the present invention, the refined aluminum liquid solution is maintained at 690°C to 700°C, allowed to stand for more than 30 minutes, and slag is removed. After that, samples are taken to measure the concentration of residual Sr in the aluminum liquid to verify whether it meets the standard. The Sr equilibrium concentration is 30-40ppm, and it is considered to meet the standard if it does not exceed 40ppm.

[0030] In a preferred embodiment of the present invention, the Sr removal agent for refining comprises the following components calculated by weight percentage, wherein the sum of the components is 100%:

[0031] NaNO3 40%-60%;

[0032] C 20%-40%;

[0033] ZnCl2 0.01%-20%.

[0034] The beneficial effects of the present invention are:

[0035] It can effectively reduce production costs, improve processing efficiency, and promote the recycling of aluminum alloy resources. The refining effect obtained is stable and meets the standards (level one), and it has broad application prospects. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described below.

[0037] A method for refining recycled aluminum alloy and removing residual Sr. On the one hand, the method uses the chemical replacement reaction between the Sr element and the inorganic salt in the high-temperature aluminum melt to reduce the residual Sr element content. The replacement reaction is: Sr+ZnCl2=SrCl2+Zn. The generated SrCl2 has a low density and floats to form slag, thereby being removed. Zn is a component of the aluminum alloy. On the other hand, the gas generated by the refining agent is used to bring Sr to the liquid surface by a physical method during the floating process, so that the slag can be removed.

[0038] The reaction principle of the refining agent is as follows: NaNO3+C→NaCO3+N2↑+CO2, NaNO3→Na2O+NO↑. The N2, NO, and CO2 gases produced after the reaction have no corrosive irritation to the human body and the environment, and the refining effect is also good. The components in the refining agent are easy to decompose at high temperatures. After production, the gas is easy to react with hydrogen, and has a strong adsorption force with slag inclusions and quickly escapes from the melt. Other components also act as slag removers.

[0039] Compared with the traditional dilution Sr removal method and the single addition of flux Sr removal method, the method of the present invention has the following advantages:

[0040] Efficient removal of residual Sr: Through specially formulated refining agents and rotary degassing technology, residual Sr in aluminum alloy recycling materials can be effectively removed, which is more efficient than traditional methods.

[0041] Reduce production costs: Using a rotary degasser and a specially formulated refining agent has lower costs and is more economical than the dilution Sr removal method, the static Sr removal method, or the separate addition of flux to remove Sr.

[0042] Improve processing efficiency: Residual Sr is removed simultaneously during the melt refining process, which reduces the processing steps, shortens the processing time, and improves the overall processing efficiency.

[0043] Expand the recycling scope of recycled aluminum-silicon alloy: It can effectively reduce the Sr concentration of recycled aluminum-silicon alloy containing Sr, improve its recycling value, and promote the recycling of aluminum alloy resources.

[0044] The process is simple and controllable: the method of combining a rotary degasser and a refining agent is adopted. The process flow is simple, easy to operate and control, and suitable for large-scale industrial production.

[0045] Significant environmental benefits: By efficiently recycling and processing Sr-containing aluminum alloy recycled materials, the generation of waste and the waste of resources are reduced, which has significant environmental benefits.

[0046] The following is explained in conjunction with embodiments:

[0047] Embodiment 1:

[0048] S1: Prepare raw materials and equipment:

[0049] Raw materials: 200 kg of aluminum alloy recycling material containing 150 ppm Sr, 1000 g of refined Sr removal agent (the ingredients are NaNO3, C, ZnCl2, of which NaNO3 accounts for 50%, C accounts for 30%, and ZnCl2 accounts for 20%).

[0050] Equipment: centralized furnace, rotary degasser, graphite rotary nozzle, industrial argon, measuring equipment.

[0051] S2: Melting aluminum alloy recycling materials:

[0052] 200 kg of Sr-containing aluminum alloy recycled material was added to a centralized furnace, the aluminum alloy was melted at 735°C, and its initial Sr concentration was measured to be 153 ppm.

[0053] S3: Adding refining Sr removal agent:

[0054] According to the initial concentration and the calculation formula: [153ppm-35ppm] / 100ppm×0.4%=0.472%, the required amount of refined Sr removal agent is calculated to be 200kg×0.472%=944g. 944g of refined Sr removal agent is added into the rotary degasser.

[0055] S4: Spin Blow Refining:

[0056] The graphite spinneret was preheated to 400°C and then placed above the aluminum liquid for spin refining. Industrial argon was used, the spinneret speed was set at 150r / min, and the spin refining time was 20 minutes.

[0057] S5: Stand and keep warm:

[0058] The aluminum liquid temperature was maintained at 700℃, and after standing for 30 minutes, the slag was removed and the residual Sr concentration was measured to be 33ppm, which met the expected standard. At the same time, the refining effect of the aluminum liquid was tested and it was grade one.

[0059] Embodiment 2:

[0060] S1: Prepare raw materials and equipment:

[0061] Raw materials: 200 kg of aluminum alloy recycling material containing 200 ppm Sr, 2000 g of refined Sr removal agent (the ingredients are NaNO3, C, ZnCl2, of which NaNO3 accounts for 40%, C accounts for 40%, and ZnCl2 accounts for 20%).

[0062] Equipment: centralized furnace, rotary degasser, graphite rotary nozzle, industrial argon, measuring equipment.

[0063] S2: Melting aluminum alloy recycling materials:

[0064] 200 kg of Sr-containing aluminum alloy recycled material was added to a centralized furnace, the aluminum alloy was melted at 735°C, and its initial Sr concentration was measured to be 200 ppm.

[0065] S3: Adding refining Sr removal agent:

[0066] According to the initial concentration and the calculation formula: [200ppm-35ppm] / 100ppm×0.4%=0.66%, the amount of refined Sr removal agent required is calculated to be 200kg×0.66%=1320g. 1320g of refined Sr removal agent is added into the rotary degasser.

[0067] S4: Spin Blow Refining:

[0068] The graphite spinneret was preheated to 400°C and then placed above the aluminum liquid for spin refining. Industrial argon was used, the spinneret speed was set at 160r / min, and the spin refining time was 20 minutes.

[0069] S5: Stand and keep warm:

[0070] The aluminum liquid temperature was maintained at 690°C, and after standing for 30 minutes, the slag was removed and the residual Sr concentration was measured to be 34ppm, which met the expected standard. At the same time, the refining effect of the aluminum liquid was tested and it was level one.

[0071] Embodiment 3:

[0072] S1: Prepare raw materials and equipment:

[0073] Raw materials: 200 kg of aluminum alloy recycling material containing 250 ppm Sr, 2000 g of refined Sr removal agent (the ingredients are NaNO3, C, ZnCl2, of which NaNO3 accounts for 60%, C accounts for 20%, and ZnCl2 accounts for 20%).

[0074] Equipment: centralized furnace, rotary degasser, graphite rotary nozzle, industrial argon, measuring equipment.

[0075] S2: Melting aluminum alloy recycling materials:

[0076] 200 kg of Sr-containing aluminum alloy recycled material was added to a centralized furnace, the aluminum alloy was melted at 735°C, and its initial Sr concentration was measured to be 256 ppm.

[0077] S3: Adding refining Sr removal agent:

[0078] According to the initial concentration and calculation formula: [256ppm-35ppm] / 100ppm×0.4%=

[0079] 0.884%, the amount of refined Sr removal agent required is calculated to be 200kg×0.884%=1768g. 1768g of refined Sr removal agent is added into the rotary degasser.

[0080] S4: Spin Blow Refining:

[0081] The graphite spinneret was preheated to 400°C and then placed above the aluminum liquid for spin refining. Industrial argon was used, the spinneret speed was set at 150r / min, and the spin refining time was 18 minutes.

[0082] S5: Stand and keep warm:

[0083] The aluminum liquid temperature was maintained at 690°C, and after standing for 30 minutes, the slag was removed and the residual Sr concentration was measured to be 32ppm, which met the expected standard. At the same time, the refining effect of the aluminum liquid was tested and it was level one.

[0084] Through the above examples, the effectiveness of the method of the present invention at different initial Sr concentrations is verified, and the residual Sr in the aluminum alloy recycling material can be efficiently removed, and the refining process of the aluminum alloy can be completed, which can reduce production costs, improve processing efficiency, and promote the recycling of aluminum alloy resources.

[0085] Table 1 is a summary of the results of various embodiments:

[0086] Table 1

[0087]

[0088] In summary, the present invention provides a method for refining recycled aluminum alloy materials and removing residual Sr. The present invention combines the two processes into one, saving a lot of time and labor costs. At the same time, the residual product Zn can also play a self-strengthening role. According to statistics, the production cost can be reduced by 10%-20%, the processing efficiency can be further improved, and the recycling of aluminum alloy resources can be promoted. The refining effect obtained is stable and meets the standards (level 1), and has broad application prospects.

[0089] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for refining recycled aluminum alloy and removing residual Sr, characterized in that: The steps include: The first step is to melt the Sr-containing aluminum alloy recycled material in a centralized furnace, wherein the melting temperature is not less than 700 degrees Celsius, and measure the initial concentration of Sr in the melted product to obtain corresponding data; The second step is to obtain the input ratio of the Sr removal agent for refining according to the data of the initial Sr concentration in the recovered aluminum according to the following formula; The amount of flux added for refining Sr removal agent (wt.%) = [Sr initial concentration (ppm) - Sr equilibrium concentration (ppm)] / 100ppm × 0.3-0.5%; The Sr equilibrium concentration is 30-40ppm; The Sr removal agent for refining includes the following components calculated by weight percentage, wherein the sum of each component is 100%: NaNO3 0.01%-99.99%; C 0.01％-99.99％； ZnCl2 0.01%-99.99%; Step 3. According to the calculated amount of flux added for refining Sr removal agent, the flux of refining Sr removal agent is placed in a rotary degasser. During the degassing process, the flux is sprayed to the bottom of the melt obtained in the first step through the graphite nozzle of the rotary degasser to remove residual Sr and obtain the refined aluminum liquid solution.

2. The method for refining aluminum alloy recycled materials and removing residual Sr as claimed in claim 1, characterized in that: The melting temperature is not less than 745 degrees Celsius.

3. The method for refining aluminum alloy recycled materials and removing residual Sr as claimed in claim 1, characterized in that: The formula is as follows: The amount of flux added for refining Sr removal agent (wt.%) = [Sr initial concentration (ppm) - Sr equilibrium concentration (ppm)] / 100ppm × 0.4%; The Sr equilibrium concentration is 35 ppm. In a preferred embodiment of the present invention, the rotary blowing refining parameters are as follows: Preheat the graphite nozzle to 350-450℃; The rotation speed of the rotary nozzle is 150-160r / min; The rotary blowing refining time is 15-20 minutes; Use industrial argon or industrial nitrogen as the cyclone gas.

4. The method for refining recycled aluminum alloy and removing residual Sr as claimed in claim 1, characterized in that: The refined aluminum liquid is maintained at 690℃ to 700℃, left to stand for more than 30 minutes, and then the slag is removed. Then, samples are taken to measure the concentration of residual Sr in the aluminum liquid to verify whether it meets the standard. The Sr equilibrium concentration is 30-40ppm, and it is considered to meet the standard if it does not exceed 40ppm.

5. The method for refining aluminum alloy recycled materials and removing residual Sr as claimed in claim 1, characterized in that: The Sr removal agent for refining includes the following components calculated by weight percentage, wherein the sum of each component is 100%: NaNO3 40%-60%; C 20％-40％； ZnCl2 0.01%-20%.

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