JP2002348621A - Pure magnesium recovery device for magnesium alloy material and method for recycling magnesium alloy material - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To efficiently and efficiently recover pure magnesium for recycling from magnesium alloy scrap material. [Solution] Molding failure, biscuit, sprue,
A crucible 1 for accommodating a raw material 20 composed of a runner, overflow, burr, cutting powder, a raw material for metal injection molding, a surface-treated product, a chip commercial scrap product, and the like, and heating devices 11, 12, and 13 for heating and melting the raw material 20; , A double cylinder 10 covering the open space of the crucible and comprising an inner sealed cylinder 3 and an outer sealed cylinder 6
And a magnesium condenser 2 arranged above the crucible 1
Cooling means 15 in the vicinity of the magnesium condenser;
An apparatus for recovering pure magnesium of a magnesium alloy material having exhaust means 17 and 19 for reducing the pressure in the double cylinder. [Effect] High-purity pure magnesium with efficient and stable quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pure magnesium magnesium alloy material capable of inexpensively and efficiently recovering high-purity pure magnesium from various scraps and the like generated in a manufacturing process of a mass-produced magnesium alloy product. The present invention relates to a recovery device and a method for recycling a magnesium alloy material.

[0002]

2. Description of the Related Art Conventionally, as a method of recycling scrap generated in a mass production type magnesium alloy high-pressure casting process (die casting, metal injection molding), several methods have been studied as shown below depending on the form. 1. 1. Re-dissolve as it is: For defective molded products with a certain size, runners, sprues, biscuits, and overflows After mechanical or chemical removal of the surface, re-dissolve:
2. For molded products after various surface treatments and recycled products in the market. After briquetting, re-melting or hot extrusion:
For sound cutting fluid that does not contain cutting oil, generated from burrs and machining of molded products

Next, each of the above methods will be specifically described. 1. To re-dissolve the scrap as it is, once reduce the volume of defective products, runners, sprues, biscuits, and overflows that occur during the molding process, store them in specified locations in the factory in appropriate conditions for each material, and After the amount is accumulated, it is transported as scrap to a recycler. At the recycler, the various scraps received are put into a melting furnace under specific conditions for each material, heated, and re-melted while using a powder flux or flux gas while minimizing the reaction between the molten magnesium alloy and the atmosphere. I do. At this time, if it is found in advance or before furnace analysis that the impurity concentration of the scrap is high, it is necessary to adjust the components by adding a predetermined raw material. After a sufficient time has passed after stirring in the melting furnace, pump out only a healthy molten metal by a predetermined method, taking care not to mix dross settled at the bottom of the furnace and sludge floating at the top of the furnace, and preheat it. Casting into the placed mold to produce recycled ingots. In addition, as long as the molding process is metal injection molding, this kind of scrap is directly pulverized and then classified into a predetermined size without going through the complicated re-melting step as described above, so that the cost can be reduced. It is also possible to obtain recycled materials.

[0004] 2. When a special lubricant or mold release agent is used in the molding step, the solid components are always involved in the surface of the portion in contact with the sleeve or the mold.
In order to remove it, it is necessary to perform mechanical or chemical treatment of the surface. In addition, mechanical or chemical treatment is also required on the surface of defective products after various surface treatments on molded products and on the surface of recycled products on the market, because a coating film mainly composed of organic compounds remains on the surface. Becomes

[0005] 3. Regarding burrs generated during molding and cutting powder generated in screw holes etc. in the post-process of molded products, prepare briquettes under appropriate temperature and pressure conditions for each material, and then use these for melting raw materials or hot extrusion. Attempts have been made to recycle the material. A metal injection molding material chip that has been stored in an inappropriate environment for a long time and has surface oxidation or impurities attached thereto can also be briquetted by the same method as described above and used as a recycling material.

[0006]

However, the conventional recycling method has the following disadvantages. 1. When re-dissolving as it is, it is necessary to thoroughly control the material in particular, but since it is impossible to distinguish the difference in material only from the appearance, it is often the case that different materials are mixed and the Was pointed out. In order to prevent this, an expensive analyzer for rapidly performing on-line composition analysis at the time of re-dissolution is required. Furthermore, sludge and dross, which are inevitably generated in large quantities during re-dissolution, are hard and difficult to treat as industrial waste.

[0007] 2. Shot blasting is mainly used to mechanically remove only the surface of molded products and recycled products in the market. However, as the processing amount is increased once, the shaded area increases and the removal efficiency decreases. There was a problem. As for the chemical treatment of the chemical conversion treatment film and the coating film, the contained components are diversified, and the stripping solution is not always present. In addition, it has been pointed out that a problem of complicated waste liquid treatment always accompanies, and it has been difficult to standardize the treatment method.

[0008] 3. Oxides are often taken into briquettes made from cutting powder, burrs, and the like, and it has been impossible to prevent the increase of dross and sludge in the molten metal or the incorporation of oxides into extruded products.

For these reasons, an apparatus for recovering pure magnesium from scrap material using a vacuum distillation apparatus has been proposed (Japanese Patent Laid-Open No. 10-158753, etc.), but the recovery efficiency is poor and the quality of the recovered material is low. However, there is also a problem that there are many variations.

The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to obtain a high-quality magnesium recycled material from a magnesium alloy scrap at low cost and easily by a vacuum distillation method. I have.

[0011]

Means for Solving the Problems To solve the above problems, the invention of the apparatus for recovering pure magnesium from a magnesium alloy material according to the first aspect of the present invention comprises a heating furnace provided with a crucible, and an inner closed space covering an open space of the crucible. A cylinder, an outer sealed cylinder arranged in the inner sealed cylinder and the double cylinder, and a magnesium capacitor material located in the inner sealed cylinder and above the crucible,
It is characterized by having a cooling means arranged close to the magnesium condenser material and an exhaust means for reducing the pressure inside the outer sealed cylinder and the inner sealed cylinder.

According to a second aspect of the present invention, there is provided an apparatus for recovering pure magnesium from a magnesium alloy material according to the first aspect, wherein the condenser has a plate shape having a vapor passage hole in a central portion. .

According to a third aspect of the present invention, there is provided an apparatus for recovering pure magnesium from a magnesium alloy material according to the first or second aspect, wherein the inner closed cylinder is covered between the inner closed cylinder and the outer sealed cylinder. A cover is arranged.

According to a fourth aspect of the present invention, there is provided an apparatus for recovering pure magnesium from a magnesium alloy material according to any one of the first to third aspects, wherein a filter for capturing an evaporator is disposed in an exhaust passage of the exhaust means. It is characterized by having been done.

According to a sixth aspect of the present invention, there is provided a method for recycling a magnesium alloy material, wherein a magnesium alloy material scrap material is inserted into a crucible and heated by using the pure magnesium recovery apparatus according to any one of the first to fifth aspects. It is characterized by condensing pure magnesium evaporated in the upper condenser.

According to a seventh aspect of the present invention, there is provided a method of recycling a magnesium alloy material according to the sixth aspect, wherein the magnesium alloy material scrap raw material is a defective molding, biscuit, sprue, runner, overflow, burr, cutting powder,
It is characterized by being made of any one of a raw material for metal injection molding, a surface-treated product, and a chip commercial scrap product.

That is, according to the present invention, when performing vacuum distillation using a magnesium alloy material such as scrap, pure magnesium can be condensed in a condenser whose temperature can be appropriately controlled by a cooling means, and the magnesium is stable. Pure magnesium having high quality can be efficiently condensed and recovered. If the temperature control of the condenser is not properly performed, impurities will be mixed and the pure magnesium condensation efficiency will decrease. Conventionally, a desired temperature can be obtained by keeping a distance from the crucible, and instability of the temperature is inevitable. The temperature management can also be performed by measuring the temperature in the condenser, the vicinity of the condenser, and the heating device, and controlling the cooling by the cooling means. The cooling control can be performed, for example, by adjusting the flow rate or temperature of the cooling medium (such as cooling water).

Also, if there is a small gap between the crucible and the condenser, the steam will escape, and a large amount of magnesium will be condensed on the inner wall of the externally sealed cylinder, and the amount of condensation in the condenser will decrease. Also, when taking out each member from the apparatus, the condensate on the inner wall of the externally sealed cylinder hinders the removal, and in many cases, the condensate cannot be removed smoothly. Is eliminated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows a vacuum distillation apparatus for recycling magnesium alloy scrap according to the present invention, that is, a pure magnesium recovery apparatus. Vacuum distillation equipment is a SUS with a bottomed cylindrical shape that accommodates and dissolves raw materials
A crucible 1 made of 430 stainless steel is provided. A magnesium condenser 2 made of SUS304 stainless steel is placed at the upper end of the crucible 1 and has a disk shape and a steam through hole 2a at the center. On the upper part of the crucible 1 and the magnesium condenser 2, an inner sealed cylinder 3 which is divided into upper and lower parts in a cylindrical shape is stacked, and the upper end of the inner sealed cylinder 3 is covered with an inner lid 4 with a handle. The upper open space of the crucible 1 is closed. The inner lid 4 has a steam vent 4a. Further, on the outer peripheral wall side of the stacked crucible 1 and the inner closed cylinder 3,
The SUS304 stainless steel cylindrical cover 5 is closely attached. The crucible 1, the inner sealed cylinder 3, and the cylindrical cover 5 are accommodated in a bottomed outer sealed cylinder 6 having a diameter larger than that of the crucible 1, and a crucible is provided at the bottom of the outer sealed cylinder 6. 1 is placed. The upper end of the outer sealing cylinder 6 has an outer lid 7
The inner cylinder 3 and the outer cylinder 6 constitute a double cylinder 10.

The outer sealed cylinder 6 accommodating the crucible 1 and the like is accommodated in a cylindrical concave portion 12 formed in an electric furnace 11 constituting a heating device, and a heater 13 is rotated so as to surround the concave portion 12. I have. In the recess 12,
A thermocouple 14 is provided as a temperature measuring means in the vicinity of the outer sealed cylinder 6.
Is arranged. A cooling water pipe 15 is arranged in the outer sealed cylinder 6 along the outer wall at a position close to the inside of the magnesium condenser 2 in height.
The water supply side and the drain side of the double cylinder 10 extend outside.
An outer air introduction pipe 1 is provided on an outer lid 7 covered by the outer sealed cylinder 6.
6 and the exhaust pipe 17 are connected, and the exhaust pipe 17
SUS3 having a mesh of 70 mesh (0.2 mm square)
It is connected to a vacuum pump 19 via 04 stainless steel filters 18a and 18b. The exhaust pipe 17, the filters 18a and 18b, and the vacuum pump 19 constitute an exhaust unit.

Next, the operation of this device will be described.
The magnesium alloy scrap 20 is stored in the crucible 1,
The inside of the double cylinder 10 is depressurized by the vacuum pump 19. Further, the heater 13 is energized to operate the electric furnace 11.
Due to the above heating, the temperature of the scrap 20 in the crucible 1 rises and melts, and some alloy components evaporate. In this evaporation, magnesium or the like having a low vapor pressure evaporates as an alloy component, and components having a high vapor pressure remain in the crucible 1. At the time of this heating, the temperature in the electric furnace 11 is measured by the thermocouple 14, and by controlling the heating temperature by adjusting the energization to the heater 13 based on the measurement result, magnesium and the magnesium can be selectively added. In addition, components having a low vapor pressure can be evaporated. In addition, water is supplied to the cooling water pipe 15 with energization of the heater 13, and the magnesium condenser 2 is maintained at an appropriate temperature (a temperature suitable for selectively condensing magnesium) by adjusting the amount of supplied water. It should be noted that the water amount adjustment can also be performed using the data of the thermocouple 14.

The alloy component evaporated from the crucible 1 by adjusting the heating temperature contacts the condenser 2. The condenser 2 is adjusted to an appropriate temperature in accordance with the magnesium.
As a result, magnesium is selectively condensed and adheres to the lower surface of the condenser 2, and gradually grows downward. On the other hand, other vaporized alloy components rise through the vapor through-holes 2 a without being condensed in the condenser 2, and further rise through the through-holes 4 of the inner lid 4 of the inner sealed cylinder 3.
Further rise through a. At this time, since the tall cylindrical cover 5 is disposed outside the inner sealed cylinder 3, magnesium vapor leaks from the gap between the crucible 1 and the condenser 2, and the steam is leaked to the inner wall of the outer sealed cylinder 6. Condensation and adhesion can be prevented, the amount of magnesium condensed in the condenser 2 can be increased, and contamination of the outer sealed cylinder 6 can be avoided. The steam is further sucked in the exhaust pipe 17, and the filters 18a, 18b
Through the vacuum pump 19. At this time, the evaporating substance is captured by the filters 18a and 18b to prevent the vacuum pump 19 from being contaminated. By continuing the above operation, the magnesium evaporated from the crucible 1 gradually adheres to the condenser 2, and high-purity magnesium can be collected in the condenser 2. In the crucible 1, the amount of magnesium gradually decreases, and finally, most of the components have a high vapor pressure.

The magnesium collected in the condenser 2 is taken out of the double cylinder 10 and used as a recycled material or the like. This magnesium has high purity,
It can be used for various purposes as a high-purity material. Moreover, since the temperature of the condenser 2 is adjusted by the cooling water pipe 15 near the condenser 2, the temperature of the condenser can be easily adjusted to an appropriate temperature, and the recovery efficiency of magnesium and the stability of quality can be improved. Is improved. In the case of magnesium alloy, from the viewpoint of corrosion resistance, it is considered that a process in which transition metal impurities such as Fe, Ni, and Cu are little mixed is necessary. However, in the recovery apparatus used in the present invention, each of the elements contained in the alloy is required. Since the process utilizes the difference between the vapor pressure and the condensation temperature, Mg, Fe, Ni, and Cu having a large difference between the vapor pressure and the condensation temperature are easily and reliably separated.

[0024]

Embodiments of the present invention will be described below. Various magnesium alloy sprue materials, AZ91D magnesium alloy mobile phone chemical conversion material and business card case coating materials of the components shown in Tables 1 and 2 were prepared as test materials for scrap. The composition analysis of each test material was performed by dissolving with HCl while the coating film was adhered, and by ICP emission spectroscopy. For example, when a business card case made of AZ91D magnesium alloy and a cross section of the coating material were observed with a scanning electron microscope (SEM),
A coating film of an organic component having a thickness of about 25 μm was adhered on the chemical conversion treatment film. In addition, about 300 g of the sprue, about 35 g of the chemical conversion treatment material, and about 50 g of the coating material were subjected to a recycling test.

In the recycling test, the test material was inserted into the crucible using the vacuum distillation apparatus shown in FIG. 1, evacuated to 1 MPa or less by an oil rotary vacuum pump, and then heated to a temperature of about 620 ° C. in an electric furnace. did. The sprue was heated for 5 hours, and the chemical conversion treatment material and the coating material were heated and held for 3 hours. After the test was completed, the amount of evaporation was determined from the amount of weight loss of the raw material in the crucible, and the amount of condensation was determined from the weight of condensate in the condenser. The evaporation amount G (%) was calculated from the following equation (1). G = 100 (W ₀ −W) / W ₀ (1) where W ₀ is the weight of the raw material before the test, and W is the weight (g) of the raw material after the test. The condensed amount d (%) was calculated from the following equation (2). D = 100 (C−C ₀ ) / W ₀ (2) where C ₀ is the weight of the capacitor before the test, and C is the weight (g) of the capacitor after the test. For the composition analysis of the condensate of the condenser, about 3 g of a sample for analysis was dissolved in HCl, diluted to 100 ml with deionized water, and Al, Zn, Fe, Cu, and N were determined by ICP emission spectroscopy.
i.

As a result of the distillation, the residue of the raw material after the test in each test material was smaller for the alloy having a larger amount of Mg, and the area where the bottom of the crucible was visible was larger. The condensate of the condenser had a larger condensed area and a thicker alloy as the Mg content was higher. FIG. 2 shows the amount of evaporation and the amount of condenser of each alloy sprue material after the recycling test. Note that the condenser condensate is the recovery rate in recycling. The amount of evaporation of each alloy was close to the evaporation limit of the amount of Mg. The amount of condenser condensed tends to increase as the amount of Mg increases, and the amount of condensate of AM50A is around 60%. From these test results, it is understood that high magnesium recovery efficiency can be obtained according to the present invention.

Next, Table 1 shows the chemical composition of the condenser condensate after the recycling test of each alloy sprue material (the results of two tests). The chemical composition of JIS H2150 magnesium metal is shown for comparison. Each of the alloys has almost the same composition as that of the JIS ingot, and it can be seen that the alloys have sufficiently high purity. Table 2 shows the chemical composition of the condenser condensate after the recycling test of the AZ91D chemical conversion treatment material and the coating material. In each case, as with the sprue material, pure magnesium almost equivalent to JIS ingot 1 was obtained, and it was found that the present invention was excellent in high purification.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

As described above, according to the present invention, it is possible to process a large amount of magnesium alloy scrap at a time without special pretreatment, and the structure of the apparatus is relatively simple, and particularly, the movable part Therefore, pure magnesium of high purity can be obtained inexpensively and efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a pure magnesium recovery apparatus according to one embodiment of the present invention.

FIG. 2 is a graph showing the amounts of evaporation and agglomeration of each alloy sprue material before and after the test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crucible 2 Magnesium condenser 3 Inner sealed cylinder 4 Inner lid 5 Cylindrical cover 6 Outer sealed cylinder 7 Outer lid 10 Double cylinder 11 Electric furnace 13 Heater 14 Thermocouple 15 Cooling water pipe 17 Exhaust pipe 18a Filter 18b Filter 19 Vacuum pump 20 scrap

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Makoto Inoue 13 Hongo-cho, Toyama-shi, Toyama F-term (reference) 4K001 AA38 BA22 DA07 EA02 GA15

Claims (7)

[Claims] 1. A crucible for accommodating a raw material, a heating device for heating and melting the raw material contained in the crucible, and an inner sealed cylinder and an outer sealed cylinder for covering and sealing the open space of the crucible. A double cylinder, a magnesium condenser located in the inner sealed cylinder above the crucible, a cooling means located near the magnesium condenser, and an exhaust means for reducing the pressure in the double cylinder A pure magnesium recovery apparatus for a magnesium alloy material, comprising: 2. The apparatus according to claim 1, wherein the magnesium condenser has a plate shape having a vapor passage hole in a central portion. 3. The pure magnesium recovery device for a magnesium alloy material according to claim 1, wherein a cylindrical cover that covers the inner sealed cylinder is disposed on an outer peripheral side of the inner sealed cylinder. 4. The apparatus according to claim 1, wherein said cooling means is located above an outer peripheral side of said magnesium condenser. 5. The filter according to claim 1, wherein a filter for trapping the evaporant is disposed in an exhaust passage of the exhaust means.
5. The apparatus for recovering pure magnesium from a magnesium alloy material according to any one of the above items 4. 6. A pure magnesium recovery apparatus according to claim 1, wherein the magnesium alloy material scrap is contained in a crucible as a raw material, heated and melted, and melted in a condenser above the crucible. A method for recycling a magnesium alloy material, comprising condensing pure magnesium evaporated from a raw material. 7. The magnesium alloy scrap material is:
7. The magnesium alloy material according to claim 6, wherein the magnesium alloy material is any of a defective molded product, a biscuit, a sprue, a runner, an overflow, a burr, a cutting powder, a raw material for metal injection molding, a surface treated product, and a chip commercial scrap product. Recycling method.