CN103966452B - A kind of recoverying and utilizing method of the magnesium alloy scrap containing aluminium - Google Patents

Abstract

A method for recycling aluminum-containing magnesium alloy waste, the invention relates to a recycling method for magnesium alloy waste, in particular to a method for preparing aluminum-magnesium master alloys from aluminum-containing magnesium alloy waste, which solves the problem of aluminum-containing The problem of low recycling rate of waste chips generated during the production and processing of magnesium alloys. Magnesium alloy waste recovery method: 1. Magnesium alloy waste is hot pressed into magnesium parts; 2. Aluminum ingot is melted; 3. Magnesium parts are pressed into the molten aluminum bell jar for smelting; 4. Add the remaining magnesium 5. Refining the melt by adding a melting agent; 6. Skimming the slag after degassing, and casting it into an ingot to obtain an aluminum-magnesium master alloy. The recycling process of the magnesium alloy waste in the present invention does not require a protective atmosphere, the oxidation and burning loss of the magnesium alloy is reduced at high temperature, the production process is simple, the use of the magnesium alloy waste reduces the production cost, and the recycling rate of the magnesium element can reach 90%. above.

Description

A kind of recycling method of aluminum-containing magnesium alloy scrap

technical field

The invention relates to a method for recycling magnesium alloy waste, in particular to a method for preparing an aluminum-magnesium master alloy by using aluminum-containing magnesium alloy waste.

Background technique

Magnesium alloy has the advantages of low density, high specific strength and specific stiffness, good thermal conductivity, good damping, vibration and noise reduction, excellent liquid forming performance, excellent machining performance, strong electromagnetic shielding ability, etc., showing extremely important use value and Broad application prospects, suitable for automobiles, motorcycles, computers, communications, instrumentation, home appliances, light industry, military and other industries.

Magnesium alloys are divided into cast magnesium alloys and wrought magnesium alloys according to the forming process. Wrought magnesium alloys are represented by AZ31 magnesium alloys, which have good ductility, medium and high strength, and are cheap. They are currently the most common wrought magnesium alloys in commercial applications. ; Cast magnesium alloy is represented by AZ91 magnesium alloy, which has high strength and excellent casting performance. However, the utilization rate of magnesium alloys in the production and processing process is not high. For example, AZ91 magnesium alloy is produced by die casting process, and the material utilization rate from production raw materials to finished products is less than 50%, resulting in a large amount of waste. How to recycle these wastes is widely discussed by people. Pay attention to.

At present, magnesium alloy waste can be recycled through solid-phase regeneration and liquid-phase regeneration. Solid phase regeneration is based on hot pressing or hot extrusion process direct forming, this method is relatively new, the technology is immature, and it is in the stage of laboratory research. Liquid phase regeneration includes distillation method, crucible furnace method, salt bath method, double furnace method, flux-free argon blowing filtration refining method and compartment gas blowing method. Distillation method is based on the principle of different vapor pressure of each element for vacuum purification, suitable for For pure magnesium, the cost of the equipment used is high, the operation is complicated, and the energy consumption is large; the crucible furnace method uses flux protection to directly heat the magnesium alloy scrap, and the flux is easy to remain in the molten metal, resulting in internal flux inclusions and reducing product quality. Harmful Cl ₂ or HCl gas will be released in the process; the salt bath method and the double furnace method can gradually purify the magnesium alloy liquid or separate the melting furnace and the casting furnace. SF ₆ atmosphere is used for protection during smelting. The main method; the flux-free argon blowing filtration refining method and the compartment gas blowing bubble method are based on stirring the molten magnesium alloy liquid while blowing argon gas at the bottom of the molten pool to generate fine bubbles to stir the melt and promote impurities. Separation, the process operation time is longer, the cost is higher, and it is rarely used in industrial production.

Because magnesium alloys are severely oxidized and burned at high temperatures, protective measures must be taken during the melting and casting process. The process is relatively complicated and the process operation time is long. At the same time, a large amount of magnesium remains in the waste residue, and the recycling rate of magnesium alloy waste is low.

Contents of the invention

The purpose of the present invention is to solve the problem of low recycling rate of waste chips generated during the production and processing of aluminum-containing magnesium alloys, and to provide a method for recycling waste chips of aluminum-containing magnesium alloys.

The recycling method of the aluminum-containing magnesium alloy waste chips of the present invention is realized in the following steps:

1. Degreasing and drying the aluminum-containing magnesium alloy waste generated during production and processing, and then hot-pressing the dried magnesium alloy waste on a press to make magnesium parts;

2. According to the chemical formula AlMgn, n is 1≦n≦20, weigh the aluminum ingots and magnesium parts according to the stoichiometric ratio, arrange the aluminum ingots along the furnace wall of the melting furnace, open the melting furnace to melt the aluminum ingots, and then spread them evenly Add the preheated smelting agent to obtain molten aluminum;

3. Raise the temperature of the molten aluminum to 740-760°C, add 1/3-1/2 of the mass of the required magnesium parts by pressing the bell jar, and stop the furnace after all the magnesium parts are melted, at a speed of 5-20cm/s Stir for 2 to 3 minutes to obtain aluminum liquid containing magnesium;

4. Raise the temperature of the smelting furnace to 740-760°C, add the remaining magnesium parts by pressing the bell jar, stop the furnace after all the magnesium parts are melted, and stir for 2-3 minutes at a speed of 5-20cm/s to obtain aluminum-magnesium liquid;

5. Heat up the smelting furnace to 740-760°C, evenly add the preheated smelting agent to the surface of the aluminum-magnesium liquid to refine the melt, and at the same time stir evenly at a speed of 5-20cm/s, and the refining time is 5-10 Minutes, after standing for 5-10 minutes, skimming to obtain molten aluminum liquid;

6. Under the condition that the molten aluminum temperature in step 5 is 720-730°C, use a rotary degasser to use a mixed gas of N ₂ and Cl ₂ for degassing treatment, and use a hydrogen detector to measure the hydrogen content. When the hydrogen content reaches When it is below 0.2ml/100gAl, stop degassing and let it stand for 10-15 minutes before skimming, and then skimming and casting into ingots when the temperature of molten aluminum is 700-730°C to obtain an aluminum-magnesium master alloy and complete aluminum-containing Recycling of magnesium alloy scrap.

Compared with the existing process for recycling magnesium alloy waste, the method for recycling aluminum-containing magnesium alloy waste in the present invention has simple equipment used in the smelting and casting process, does not require a protective atmosphere, and reduces oxidation and burning of the magnesium alloy at high temperatures. Simple, while using magnesium alloy waste chips, the production cost is significantly reduced.

The advantage of the method for recycling aluminum-containing magnesium alloy scraps of the present invention is that the discarded magnesium alloy scraps produced during the production process can be reused, and at the same time, a relatively low price and qualified aluminum-magnesium master alloy can be produced, which can make the magnesium element The recycling rate reaches more than 90%.

Detailed ways

Specific implementation mode one: the recycling method of the aluminum-containing magnesium alloy waste of the present implementation mode is implemented according to the following steps:

1. Degreasing and drying the aluminum-containing magnesium alloy waste generated during production and processing, and then hot-pressing the dried magnesium alloy waste on a press to make magnesium parts;

2. According to the chemical formula AlMgn, n is 1≦n≦20, weigh the aluminum ingots and magnesium parts according to the stoichiometric ratio, arrange the aluminum ingots along the furnace wall of the melting furnace, open the melting furnace to melt the aluminum ingots, and then spread them evenly Add the preheated smelting agent to obtain molten aluminum;

3. Raise the temperature of the molten aluminum to 740-760°C, add 1/3-1/2 of the mass of the required magnesium parts by pressing the bell jar, and stop the furnace after all the magnesium parts are melted, at a speed of 5-20cm/s Stir for 2 to 3 minutes to obtain aluminum liquid containing magnesium;

4. Raise the temperature of the smelting furnace to 740-760°C, add the remaining magnesium parts by pressing the bell jar, stop the furnace after all the magnesium parts are melted, and stir for 2-3 minutes at a speed of 5-20cm/s to obtain aluminum-magnesium liquid;

5. Heat up the smelting furnace to 740-760°C, evenly add the preheated smelting agent to the surface of the aluminum-magnesium liquid to refine the melt, and at the same time stir evenly at a speed of 5-20cm/s, and the refining time is 5-10 Minutes, after standing for 5-10 minutes, skimming to obtain molten aluminum liquid;

6. Under the condition that the molten aluminum temperature in step 5 is 720-730°C, use a rotary degasser to use a mixed gas of N ₂ and Cl ₂ for degassing treatment, and use a hydrogen detector to measure the hydrogen content. When the hydrogen content reaches When it is below 0.2ml/100gAl, stop degassing and let it stand for 10-15 minutes before skimming, and then skimming and casting into ingots when the temperature of molten aluminum is 700-730°C to obtain an aluminum-magnesium master alloy and complete aluminum-containing Recycling of magnesium alloy scrap.

Step 2 of this embodiment evenly sprinkles the preheated smelting agent to reduce the burning loss of the molten aluminum.

The usage amount of the smelting agent in step 2 and step 5 of this embodiment is 0.5%-0.8% of the weight of the molten metal, and it is advisable to completely cover the surface of the molten metal in step 2. The role of uniform stirring at a speed of 5-20 cm/s in step five is to more effectively exert the refining effect of the melting agent on the melt.

Embodiment 2: This embodiment differs from Embodiment 1 in that the mass of each magnesium piece in Step 1 is 0.25-2.0 kg. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 3: This embodiment is different from Embodiment 2 in that the shape of the magnesium piece in step 1 is a rectangular block or cake. Other steps and parameters are the same as in the second embodiment.

Embodiment 4: This embodiment differs from Embodiments 1 to 3 in that the temperature of hot pressing in step 1 is 150-350° C., and the pressure of hot pressing is 120-300 MPa. Other steps and parameters are the same as those in Embodiments 1 to 3.

Embodiment 5: The difference between this embodiment and Embodiment 1 to 4 is that the smelting agent described in step 2 and step 5 is composed of 35% to 41% _KCl and 40% to 46% MgCl by weight percentage. , 5% to 8% of BaCl ₂ , 3% to 5% of CaF ₂ , NaCl+CaCl ₂ ≤ 6% and MgO ≤ 1.5%. Other steps and parameters are the same as in one of the specific embodiments 1 to 4.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that the smelting agent after the preheating treatment described in Step 2 and Step 5 is dried at a temperature of 120-180°C to the H ₂ in the smelting agent The mass content of O is obtained below 0.5%. Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Specific embodiment 7: The difference between this embodiment and one of the specific embodiments 1 to 6 is that step 3 adopts the bell jar to press-in to add 1/3 to 1/2 of the mass of the required magnesium parts, and the bell jar moves to the smelting furnace The furnace bottom distance is 100mm. Other steps and parameters are the same as one of the specific embodiments 1 to 6.

In this embodiment, the bell jar is press-fitted to add magnesium parts, and there is a certain space between the bell jar and the bottom of the furnace, and the bell jar can move horizontally in the melt.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is that step 5 uses a bell jar to press-in to add the remaining magnesium parts, wherein the bell jar moves to a distance of 100 mm from the furnace bottom of the melting furnace. Other steps and parameters are the same as one of the specific embodiments 1 to 7.

Embodiment one: the present embodiment adopts AZ91 magnesium alloy shavings to prepare the method for aluminum-magnesium master alloy AlMg10 to implement according to the following steps:

1. Degreasing and drying the magnesium alloy waste generated during production and processing, and then hot pressing the dried magnesium alloy waste through a press at a hot pressing temperature of 300°C and a hot pressing pressure of 180Mpa to make each A 1kg piece of magnesium;

2. According to the chemical formula AlMg10, weigh the aluminum ingots and magnesium parts according to the stoichiometric ratio, arrange the aluminum ingots along the furnace wall of the melting furnace, turn on the melting furnace to melt the aluminum ingots, and then evenly sprinkle the preheated smelting agent to obtain liquid aluminum;

3. Raise the temperature of the molten aluminum to 760°C, add 7kg of magnesium parts by pressing in a bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 5cm/s to obtain a molten aluminum containing magnesium;

4. Raise the temperature of the smelting furnace to 760°C, add the remaining 7kg of magnesium parts by pressing the bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 5cm/s to obtain aluminum-magnesium liquid;

5. Heat up the melting furnace to 740°C, evenly add the preheated melting agent to the surface of the aluminum-magnesium liquid to refine the melt, and at the same time stir evenly at a speed of 10cm/s, the refining time is 10 minutes, and stand for 5 minutes Post skimming to obtain molten aluminum;

6. Under the condition that the molten aluminum temperature in step 5 is 730°C, use a rotary degasser to use a mixed gas of N ₂ and Cl ₂ for degassing treatment, and use a hydrogen detector to measure the hydrogen content. When the hydrogen content reaches 0.2ml /100gAl or less, stop degassing and let it stand for 15 minutes to skim off the slag, then skim off the slag and cast it into an ingot when the temperature of the molten aluminum is 720°C to obtain an aluminum-magnesium master alloy and complete the recovery of aluminum-containing magnesium alloy waste use.

The recovery rate of Mg in this embodiment is 90.31%, and the specific experimental data are shown in Table 1 below.

Table 1

Embodiment two: the method that present embodiment adopts AZ31 magnesium alloy shavings to prepare aluminum-magnesium master alloy AlMg5 is implemented according to the following steps:

1. Degreasing and drying the magnesium alloy waste generated during production and processing, and then hot pressing the dried magnesium alloy waste in a press at a hot pressing temperature of 200°C and a hot pressing pressure of 150Mpa to make each A 1.5kg piece of magnesium;

2. According to the chemical formula AlMg5, weigh the aluminum ingots and magnesium parts according to the stoichiometric ratio, arrange the aluminum ingots along the furnace wall of the melting furnace, turn on the melting furnace to melt the aluminum ingots, and then evenly sprinkle the preheated smelting agent to obtain liquid aluminum;

3. Raise the temperature of the molten aluminum to 740°C, add 2kg of magnesium parts by pressing in a bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 10cm/s to obtain a molten aluminum containing magnesium;

4. Raise the temperature of the smelting furnace to 740°C, add the remaining 4kg of magnesium parts by pressing the bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 10cm/s to obtain aluminum-magnesium liquid;

5. Heat up the melting furnace to 740°C, evenly add the preheated melting agent to the surface of the aluminum-magnesium liquid to refine the melt, and at the same time stir evenly at a speed of 10cm/s, the refining time is 8 minutes, and stand for 10 minutes Post skimming to obtain molten aluminum;

6. Under the condition that the molten aluminum temperature in step 5 is 730°C, use a rotary degasser to use a mixed gas of N ₂ and Cl ₂ for degassing treatment, and use a hydrogen detector to measure the hydrogen content. When the hydrogen content reaches 0.2ml /100gAl or less, stop degassing and let it stand for 10 minutes before skimming, then skimming and casting into ingots when the temperature of molten aluminum is 710°C, to obtain aluminum-magnesium master alloys, and complete the recovery of aluminum-containing magnesium alloy waste use.

The recovery rate of Mg in this embodiment is 92.32%, and the specific experimental data is shown in Table 2 below.

Table 2

Embodiment three: the present embodiment adopts AZ61 magnesium alloy shavings to prepare the method for aluminum-magnesium master alloy AlMg10 to implement according to the following steps:

1. Degreasing and drying the magnesium alloy waste generated during production and processing, and then hot-pressing the dried magnesium alloy waste in a press at a hot-pressing temperature of 250°C and a hot-pressing pressure of 200Mpa to make each A 0.5kg piece of magnesium;

2. According to the chemical formula AlMg10, weigh the aluminum ingots and magnesium parts according to the stoichiometric ratio, arrange the aluminum ingots along the furnace wall of the melting furnace, turn on the melting furnace to melt the aluminum ingots, and then evenly sprinkle the preheated smelting agent to obtain liquid aluminum;

3. Raise the temperature of the molten aluminum to 740°C, add 6.5kg of magnesium parts by pressing in a bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 8cm/s to obtain a molten aluminum containing magnesium;

4. Raise the temperature of the smelting furnace to 740°C, add the remaining 6.5 kg of magnesium parts by pressing the bell jar, stop the furnace after all the magnesium parts are melted, and stir for 3 minutes at a speed of 8 cm/s to obtain aluminum-magnesium liquid;

5. Heat up the melting furnace to 740°C, evenly add the preheated melting agent to the surface of the aluminum-magnesium liquid to refine the melt, and at the same time stir evenly at a speed of 5cm/s, the refining time is 8 minutes, and stand for 10 minutes Post skimming to obtain molten aluminum;

6. Under the condition that the molten aluminum temperature in step 5 is 720°C, use a rotary degasser to use a mixed gas of N ₂ and Cl ₂ for degassing treatment, and use a hydrogen detector to measure the hydrogen content. When the hydrogen content reaches 0.2ml /100gAl or less, stop degassing and let it stand for 10 minutes before skimming, and then skimming and casting into ingots when the temperature of molten aluminum is 700°C, to obtain aluminum-magnesium master alloys, and complete the recovery of aluminum-containing magnesium alloy waste use.

The recovery rate of Mg in this embodiment is 90.70%, and the specific experimental data is shown in Table 3 below.

Claims (7)

1., containing a recoverying and utilizing method for the magnesium alloy scrap of aluminium, it is characterized in that following these steps to realize containing the recoverying and utilizing method of the magnesium alloy scrap of aluminium:

One, the magnesium alloy scrap oil removing post-drying containing aluminium will produced in process for processing, then makes magnesium part magnesium alloy scrap hot pressing on pressing machine of drying;

Two, be 1≤n≤20 according to chemical formula AlMgn, n, stoichiometrically take aluminium ingot bar and magnesium part, along the furnace wall arrangement aluminium ingot bar of smelting furnace, open smelting furnace melting aluminum ingot, then evenly sprinkle the smelting agent after thermal pretreatment, obtain aluminium liquid;

Three, aluminium liquid is warming up to 740 ~ 760 DEG C, adopts that bell jar is forced adds 1/3 ~ 1/2 of required magnesium part quality, blowing out after magnesium part all melts, stir 2 ~ 3 minutes with the speed of 5 ~ 20cm/s, obtain the aluminium liquid containing magnesium;

Four, smelting furnace is warming up to 740 ~ 760 DEG C, adopts that bell jar is forced adds remaining magnesium part, blowing out after magnesium part all melts, stir 2 ~ 3 minutes with the speed of 5 ~ 20cm/s, obtain magnalium liquid;

Five, smelting furnace is warming up to 740 ~ 760 DEG C, add the smelting agent after thermal pretreatment at magnalium liquid surface uniform and carry out refining to melt, simultaneously with the speed uniform stirring of 5 ~ 20cm/s, refining time is 5 ~ 10 minutes, leave standstill skimming after 5 ~ 10 minutes, obtain molten aluminum liquid;

Six, under the molten aluminum liquid temperature of step 5 is the condition of 720 ~ 730 DEG C, rotary degassing machine is utilized to use N ₂with Cl ₂mixed gas carry out degassing processing, hydrogen meter is utilized to measure hydrogen richness, when hydrogen richness reaches below 0.2ml/100gAl, degasification is stopped to leave standstill skimming after 10 ~ 15 minutes, and then carry out skimming when molten aluminum liquid temperature is 700 ~ 730 DEG C and be cast into ingot, obtain magnalium master alloy, complete the recycling of the magnesium alloy scrap containing aluminium;

Step 2 and the smelting agent described in step 5 by weight percentage by 35% ~ 41% KCl, the MgCl of 40% ~ 46% ₂, the BaCl of 5% ~ 8% ₂, the CaF of 3% ~ 5% ₂, NaCl+CaCl ₂≤ 6% and MgO≤1.5% form;

In step 2 and step 5, the usage quantity of smelting agent is 0.5% ~ 0.8% of metal melt weight.

2. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, is characterized in that the quality of every block magnesium part in step one is 0.25 ~ 2.0kg.

3. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, is characterized in that the shape of magnesium part described in step one is rectangular block shape or pie.

4. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, it is characterized in that the temperature of step one hot pressing is 150 ~ 350 DEG C, the pressure of hot pressing is 120 ~ 300MPa.

5. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, is characterized in that the smelting agent after the thermal pretreatment described in step 2 and step 5 is dried to H in smelting agent at 120 ~ 180 DEG C of temperature ₂the mass content of O obtains below 0.5%.

6. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, it is characterized in that step 3 adopts that bell jar is forced adds 1/3 ~ 1/2 of required magnesium part quality, it is 100mm place that its middle bell jar moves to the furnace bottom distance of smelting furnace.

7. the recoverying and utilizing method of a kind of magnesium alloy scrap containing aluminium according to claim 1, it is characterized in that step 5 adopts that bell jar is forced adds remaining magnesium part, it is 100mm place that its middle bell jar moves to the furnace bottom distance of smelting furnace.