阅读说明：本技术 一种基于热浮力净化铝合金熔体的方法 (Method for purifying aluminum alloy melt based on thermal buoyancy ) 是由 向林 陶健全 李明 陈强 彭菲菲 邢志辉 黄志伟 赵高瞻 孙际鹏 刘鹏 于 2021-09-09 设计创作，主要内容包括：本发明提供了一种基于热浮力净化铝合金熔体的方法,包括用于熔化铝合金的坩埚,坩埚设置在炉体上,其特征在于：铝合金熔体净化过程中,始终控制坩埚内的熔体按区域产生梯度温度,且熔体的最低温度不小于铝合金熔点,熔体的最高温度不大于熔体中悬浮杂质的熔点。采用本发明方案净化后的铝合金熔体,其纯度高；采用本发明方案净化铝合金熔体,不仅所需设施非常简单,只需要采用常规的坩埚、加热炉、滤网和加热丝,而且熔体净化成本低,还便于控制熔体温度场；采用本发明方案净化后铝合金熔体,整个操作过程无任何污染。(The invention provides a method for purifying an aluminum alloy melt based on thermal buoyancy, which comprises a crucible for melting aluminum alloy, wherein the crucible is arranged on a furnace body, and is characterized in that: during the purification process of the aluminum alloy melt, the melt in the crucible is always controlled to generate gradient temperature according to regions, the lowest temperature of the melt is not less than the melting point of the aluminum alloy, and the highest temperature of the melt is not more than the melting point of suspended impurities in the melt. The aluminum alloy melt purified by the scheme of the invention has high purity; by adopting the scheme of the invention to purify the aluminum alloy melt, the required facilities are very simple, only the conventional crucible, heating furnace, filter screen and heating wire are needed, the melt purification cost is low, and the melt temperature field is convenient to control; the aluminum alloy melt purified by the scheme of the invention has no pollution in the whole operation process.)

1. A method for purifying an aluminum alloy melt based on thermal buoyancy comprises a crucible for melting aluminum alloy, the crucible is arranged on a furnace body, and the method is characterized in that: during the purification process of the aluminum alloy melt, the melt in the crucible is always controlled to generate gradient temperature according to regions, the lowest temperature of the melt is not less than the melting point of the aluminum alloy, and the highest temperature of the melt is not more than the melting point of suspended impurities in the melt.

2. The method of claim 1, wherein: controlling the temperature gradient of the melt in the crucible to gradually decrease from bottom to top; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

3. The method of claim 2, wherein: dividing a melt in a crucible into three regions along an axis direction, wherein two rows of resistance wires are arranged on a furnace body corresponding to an upper region, four rows of resistance wires are arranged on the furnace bodies corresponding to a middle region and a lower region respectively, and the axial distance between the adjacent resistance wires in the middle region is larger than that between the adjacent resistance wires in the lower region; when melting, the resistance wires of the 1 st row and the 5 th row from bottom to top are in a power-off state; after the materials are completely melted and reach 730 +/-5 ℃, the resistance wires in the 1 st row and the 5 th row from bottom to top are started to heat, so that the melt temperature of the upper area is lower than that of the middle area, and the melt temperature of the middle area is lower than that of the lower area.

4. The method of claim 3, wherein: the axial distance between two rows of resistance wires corresponding to the upper area is 30mm, the axial distance between adjacent resistance wires corresponding to the middle area is 20mm, and the axial distance between adjacent resistance wires corresponding to the lower area is 10 mm.

5. The method of claim 4, wherein: after the materials are completely melted and before the 1 st row and the 5 th row of resistance wires from bottom to top are opened, a plurality of layers of filter screens with pull wires are laid on the inner wall of the crucible; and in the purification process of the aluminum alloy melt, slowly pulling out a layer of filter screen at intervals of 3-5 minutes.

6. The method of claim 1, wherein: controlling the melt in the crucible to form a temperature gradient with gradually increasing temperature from bottom to top, placing a filter screen in the crucible, and pressing the filter screen downwards to enable the filter screen to be attached to the inner wall of the crucible.

7. The method of claim 6, wherein: dividing the melt in the crucible into three regions along the axis direction, wherein five rows of resistance wires are respectively arranged on the furnace bodies corresponding to the upper region, the middle region and the lower region, and the axial distance between the adjacent resistance wires is 10 mm; when melting, all resistance wires are opened; when the melt is completely melted and reaches 730 +/-5 ℃, the resistance wires in the 7 th row, the 9 th row, the 11 th row, the 13 th row and the 15 th row from bottom to top are closed and then heated, so that the melt temperature of the upper area is lower than that of the middle area, and the melt temperature of the middle area is lower than that of the lower area; when the temperature of the melt reaches 810 +/-5 ℃, fishing out impurities on the surface layer of the melt, and closing all resistance wires until the melt is cooled to 730 +/-5 ℃; and then, turning off resistance wires of the 1 st row, the 3 rd row, the 5 th row, the 7 th row and the 9 th row from bottom to top, and heating after turning on all the other resistance wires to ensure that the melt temperature of the upper area is higher than that of the middle area and the melt temperature of the middle area is higher than that of the lower area.

8. The method of claim 7, wherein: after the resistance wires of the 1 st row, the 3 rd row, the 5 th row, the 7 th row and the 9 th row from bottom to top are closed, a layer of filter screen is put into the crucible at intervals of 3-5 minutes, and the filter screen and the crucible are ensured to be coaxial in the putting process; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

9. The method according to any one of claims 6-8, wherein: the suspended impurities in the aluminum alloy melt are mainly Al2O3 and/or CuO and/or TiO with the diameter of less than 50 mu m; the difference of the melt temperatures of adjacent areas is not less than 25 ℃; and purifying the aluminum alloy melt under an inert atmosphere.

10. The method of claim 9, wherein: the filter screen is a cylindrical structure matched with the inner wall of the crucible, and the outer diameter of the filter screen is equal to the inner diameter of the crucible.

Technical Field

The invention relates to the technical field of aluminum alloy casting, in particular to a method for purifying an aluminum alloy melt based on thermal buoyancy, wherein the thermal buoyancy is an acting force which is generated by the melt due to the temperature difference and enables the melt to flow from a high-temperature layer to a low-temperature layer.

Background

The traditional aluminum alloy melt purification comprises refining agent refining, hexachloroethane refining, inert gas purification and other modes, on the basis, scholars provide purification methods such as gas-powder composite purification, external magnetic field purification and ultrasonic purification, so that the purification effect of the aluminum alloy melt is remarkably improved. For example, document CN107805723A discloses a method for purifying an aluminum alloy melt, which comprises: heating the aluminum alloy raw material in the crucible furnace to the temperature of 720-740 ℃ to prepare a melt, enabling the rotating arm to rotate and stir at a constant speed in the aluminum alloy melt, simultaneously introducing mixed gas of N2 and Cl2 and a refining agent, and simultaneously removing scum on the surface of the aluminum alloy melt; further, as disclosed in document CN1168839C, a method for continuously purifying and purifying high-purity aluminum in vacuum is disclosed, which comprises evacuating a purification furnace body, introducing aluminum liquid into a purification crucible in the furnace body through a pipeline and a stop valve by utilizing an air pressure difference between the purification furnace and an electrolytic bath, evacuating a waste liquid recovery furnace, introducing a certain amount of protective gas into the purification furnace body, and generating a pressure difference between the recovery furnace and the purification furnace; and every 0.5-3h, utilizing pressure difference to transfer the liquid layer enriched with the impurity elements through a pipette.

However, the effect of the existing melt purification methods still needs to be improved, some purification methods require complicated facilities and are high in cost, and the individual purification methods also have the pollution problems, such as chlorine gas generated during refining by hexachloroethane, environmental pollution and damage to the health of workers. In consideration of environmental protection requirements, a physical refining method should be adopted as much as possible during refining.

Disclosure of Invention

The invention aims to provide a method for purifying an aluminum alloy melt based on thermal buoyancy, which has the advantages of good melt purification effect, simple required facilities, low purification cost, environmental protection, no pollution and the like.

In order to achieve the above object, the present invention adopts the following technical solutions.

The utility model provides a method for purify aluminum alloy fuse-element based on thermal buoyancy, includes the crucible that is used for melting the aluminum alloy, and the crucible sets up on the furnace body, and the effect of furnace body is through resistance wire circular telegram production heat, and then makes the aluminum alloy ingot material in the crucible melt into the fuse-element, sets up the thermocouple in the different regions of furnace body, and the other end connection control system of thermocouple feeds back the temperature in each region in real time to can calculate temperature gradient, its characterized in that: during the purification process of the aluminum alloy melt, the melt in the crucible is always controlled to generate gradient temperature according to regions, the lowest temperature of the melt is not less than the melting point of the aluminum alloy, and the highest temperature of the melt is not more than the melting point of suspended impurities in the melt.

As a preferred scheme of the invention, the temperature gradient with gradually reduced temperature is always controlled to be formed by the melt in the crucible from bottom to top; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

In order to further improve the purification effect of the aluminum alloy melt and simplify the melt purification facility, the melt in the crucible is divided into three areas along the axis direction, two rows of resistance wire crucible outer walls are arranged on the furnace body corresponding to the upper area, four rows of resistance wires are respectively arranged on the furnace bodies corresponding to the middle area and the lower area, and the axial distance between the adjacent resistance wires in the middle area is larger than that between the adjacent resistance wires in the lower area; when melting, the resistance wires of the 1 st row and the 5 th row from bottom to top are in a power-off state; after the melt is completely melted and reaches 730 +/-5 ℃, the resistance wires in the 1 st row and the 5 th row from bottom to top are started to heat, so that the melt temperature of the upper area is lower than that of the middle area, and the melt temperature of the middle area is lower than that of the lower area.

In order to further improve the purification effect of the aluminum alloy melt, the axial distance between two rows of resistance wires corresponding to the upper area is 30mm, the axial distance between adjacent resistance wires corresponding to the middle area is 20mm, and the axial distance between adjacent resistance wires corresponding to the lower area is 10 mm.

In order to further improve the purification effect of the aluminum alloy melt, after the aluminum alloy is completely melted and before the 1 st row and the 5 th row of resistance wires from bottom to top are opened, a plurality of layers of filter screens with pull wires are laid on the inner wall of the crucible; and in the purification process of the aluminum alloy melt, slowly pulling out a layer of filter screen at intervals of 3-5 minutes.

As another preferable scheme of the invention, the temperature gradient of the melt in the crucible is controlled to form a temperature gradient with gradually increasing temperature from bottom to top, a filter screen is placed in the crucible, and the filter screen is pressed down to be attached to the inner wall of the crucible.

In order to further improve the purification effect of the aluminum alloy melt, the melt in the crucible is divided into three areas along the axis direction, five rows of resistance wires are respectively arranged on the furnace bodies corresponding to the upper area, the middle area and the lower area, and the axial distance between the adjacent resistance wires is 10 mm; when melting, all resistance wires are opened; when the melt is completely melted and reaches 730 +/-5 ℃, the resistance wires in the 7 th row, the 9 th row, the 11 th row, the 13 th row and the 15 th row from bottom to top are closed and then heated, so that the melt temperature of the upper area is lower than that of the middle area, and the melt temperature of the middle area is lower than that of the lower area; when the temperature of the melt reaches 810 +/-5 ℃, fishing out impurities on the surface layer of the melt, and closing all resistance wires until the melt is cooled to 730 +/-5 ℃; and then, turning off resistance wires of the 1 st row, the 3 rd row, the 5 th row, the 7 th row and the 9 th row from bottom to top, and heating after turning on all the other resistance wires to ensure that the melt temperature of the upper area is higher than that of the middle area and the melt temperature of the middle area is higher than that of the lower area.

In order to further improve the purification effect of the aluminum alloy melt, after the resistance wires of the 1 st row, the 2 nd row, the 5 th row, the 7 th row and the 9 th row from bottom to top are closed, a layer of filter screen is put into the crucible at intervals of 3-5 minutes, and the filter screen and the crucible are ensured to be coaxial in the putting process; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

In the invention, suspended impurities in the aluminum alloy melt are mainly Al2O3 and/or CuO and/or TiO with the diameter of less than 50 mu m; the temperature difference of the melts of adjacent areas is not less than 25 ℃, and the purification of the aluminum alloy melts is carried out in an inert atmosphere.

More preferably, the filter screen is a cylindrical structure matched with the inner wall of the crucible, and the outer diameter of the filter screen is equal to the inner diameter of the crucible.

Has the advantages that: by adopting the scheme of the invention to purify the aluminum alloy melt, the deslagging rate can reach 95 percent; by adopting the scheme of the invention to purify the aluminum alloy melt, the required facilities are very simple, only the conventional crucible, heating furnace, filter screen and heating wire are needed, the melt purification cost is low, the purification cost is less than 50% of the purification cost of the conventional methods such as gas-powder composite purification, external magnetic field purification, ultrasonic purification and the like, the melt temperature field is convenient to control, and the invention has the advantages of simple and easy operation process and the like; the aluminum alloy melt purified by the scheme of the invention has no pollution in the whole operation process.

Drawings

FIG. 1 is a schematic view of a facility for purifying an aluminum alloy melt in example 1.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments, but the following embodiments are only used for understanding the principle of the present invention and the core idea thereof, and do not limit the scope of the present invention. It should be noted that modifications to the invention as described herein, which do not depart from the principles of the invention, are intended to be within the scope of the claims which follow.

Example 1

A method for purifying an aluminum alloy melt based on thermal buoyancy comprises a crucible 4 for melting an aluminum alloy, wherein the crucible 4 is cylindrical, the bottom of the crucible 4 is hemispherical, the crucible 4 can contain 1000kg of the aluminum alloy melt, the melting rate is 500kg/h, the crucible 4 is arranged on a furnace body, the furnace body is used for generating heat through electrifying a resistance wire 5 so as to melt an aluminum alloy ingot in the crucible 4 into the melt, thermocouples are arranged in different areas of the furnace body, the other end of each thermocouple is connected with a control system, the temperature of each area is fed back in real time, and the temperature gradient can be calculated; during the purification process of the aluminum alloy melt, the melt in the crucible 4 is always controlled to form a temperature gradient with gradually decreasing temperature from bottom to top, the lowest temperature of the melt is not less than the melting point of the aluminum alloy, the highest temperature of the melt is not more than the melting point of suspended impurities in the melt, and the suspended impurities in the aluminum alloy melt are mainly Al2O3 and/or CuO and/or TiO with the diameter of less than 50 mu m. Specifically, the method comprises the following steps: dividing a melt in a crucible 4 into three regions along an axis direction, wherein two rows of resistance wires 5 are arranged on a furnace body corresponding to an upper region 3, the axial distance 3d between the two rows of resistance wires 5 corresponding to the upper region 3 is 30mm, four rows of resistance wires 5 are respectively arranged on the furnace bodies corresponding to a middle region 1 and a lower region 1, each row of resistance wires is started and stopped independently through a control system, the axial distance 2d between adjacent resistance wires 5 corresponding to the middle region 2 is 20mm, and the axial distance 1d between adjacent resistance wires 5 corresponding to the lower region 1 is 10 mm; when melting, the resistance wires 5 of the 1 st row and the 5 th row from bottom to top are in a power-off state; after the melt is completely melted and reaches 730 +/-5 ℃, the resistance wires 5 in the 1 st row and the 5 th row from bottom to top are started to heat, so that the melt temperature of the upper area 3 is lower than the melt temperature of the middle area 2, the melt temperature of the middle area 2 is lower than the melt temperature of the lower area 1, and in the process, suspended impurities in the melt float up to the surface layer of the melt under the action of thermal buoyancy.

Example 2

A method for purifying an aluminum alloy melt based on thermal buoyancy is disclosed, which is mainly different from example 1 in that: after the melt is completely melted and before the 1 st row and the 5 th row of resistance wires 5 from bottom to top are opened, five layers of filter screens with pull wires are laid on the inner wall of the melt, the filter screens are of cylindrical structures matched with the inner wall of the crucible 4, the diameter of each filter screen is equal to the inner diameter of the crucible 4, and the pull wires are made of titanium alloy wires; after purifying the aluminum alloy melt for 10 minutes, slowly pulling out a layer of filter screen at intervals of 3-5 minutes; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

Example 3

A method for purifying an aluminum alloy melt based on thermal buoyancy comprises a crucible for melting an aluminum alloy, wherein the crucible is cylindrical, the bottom of the crucible is hemispherical, the crucible can contain 1500kg of the aluminum alloy melt, the melting rate is 500kg/h, the crucible is arranged on a furnace body, the arrangement mode of the crucible and the furnace body is shown in figure 1, the furnace body is used for generating heat by electrifying a resistance wire (the resistance wire is arranged around the crucible), so that an aluminum alloy ingot in the crucible is melted into the melt, thermocouples are arranged in different areas of the furnace body, the other ends of the thermocouples are connected with a control system, the temperature of each area is fed back in real time, and the temperature gradient can be calculated; the purification process of the aluminum alloy melt is carried out in an inert atmosphere; the lowest temperature of the melt is not less than the melting point of the aluminum alloy, the highest temperature of the melt is not more than the melting point of suspended impurities in the melt, and the suspended impurities in the aluminum alloy melt are mainly Al2O3 and/or CuO and/or TiO with the diameter of less than 50 mu m. Specifically, the method comprises the following steps: dividing the melt in the crucible into three regions along the axis direction, wherein five rows of resistance wires are respectively arranged on the furnace bodies corresponding to the upper region, the middle region and the lower region, and the axial distance between the adjacent resistance wires is 10 mm; when melting, all resistance wires are opened; when the aluminum alloy in the crucible is completely melted and reaches 730 +/-5 ℃, the resistance wires in the 7 th row, the 9 th row, the 11 th row, the 13 th row and the 15 th row from bottom to top are closed and then heated, so that the temperature of the melt in the upper area is lower than that of the melt in the middle area, and the temperature of the melt in the middle area is lower than that of the melt in the lower area, and in the process, suspended impurities in the melt float up to the surface layer of the melt under the action of thermal buoyancy; when the temperature of the melt is even 810 +/-5 ℃, fishing out impurities on the surface layer of the melt, and closing all resistance wires until the melt is cooled to 730 +/-5 ℃; then, turning off resistance wires of the 1 st row, the 3 rd row, the 5 th row, the 7 th row and the 9 th row from bottom to top, and turning on all the resistance wires to heat, so that the melt temperature of the upper region is higher than that of the middle region, and the melt temperature of the middle region is higher than that of the lower region, in the process, the thermal force overcomes the viscosity resistance of the melt, and suspended impurities in the melt sink under the action of the thermal force and the gravity; after the resistance wires of the 1 st row, the 3 rd row, the 5 th row, the 7 th row and the 9 th row from bottom to top are closed, a layer of filter screen (filter cylinder) is put into the crucible every 3-5 minutes, five layers of filter screens are put into the crucible, the filter screen is pressed down to be attached to the inner wall of the crucible, and the filter screen (filter cylinder) is ensured to be coaxial with the crucible in the putting process; and after the aluminum alloy melt is purified, discarding the surface melt and the bottom melt.

The slag removal rate tests of the purified melts in examples 1 to 3 respectively show that the slag removal rate in example 1 is 85 to 89.5 percent, the slag removal rate in example 2 is 93.1 to 94.2 percent, and the slag removal rate in example 3 is 93.5 to 95.7 percent.

The aluminum alloy melt purified by the scheme of the invention has high deslagging rate, the required facilities are very simple, only the conventional crucible, heating furnace, filter screen and heating wire are required, the melt purification cost is low, the purification cost is less than 50% of that of the conventional methods such as gas-powder composite purification, external magnetic field purification, ultrasonic purification and the like, the melt temperature field is convenient to control, and the method has the advantages of simple and easy operation process and the like; the aluminum alloy melt purified by the scheme of the invention has no pollution in the whole operation process.