JPS61243133A - Filter device for regeneration of metallic scrap - Google Patents

Abstract

PURPOSE:To regenerate efficiently metallic scrap by superposing an upper vessel and lower vessel contg. respectively crucibles, supplying the metallic strip into the crucible in the upper vessel, heating the scrap to form a molten metal and filtering the molten metal into the crucible in the lower vessel via a filter. CONSTITUTION:The metallic scrap is supplied into the crucible 3 in the upper vessel 1 and while the oxidation is prevented in the atmosphere consisting of gaseous SF6 and dry air, the scrap is heated and melted by a heating coil 1A. The inside of the crucible 3 is pressurized from a gas supply path 10 for pressure filtration or the inside of the crucible 4 in the vessel 2 is evacuated through a suction path 12 for evacuation to filter the molten metal through the filter 22 into the crucible 4 when a temp. sensor 9 detects that the molten metal attains the required filtration temp. The vessel 1 is hoisted by a lifting device upon completion of the filtration. The vessel 2 is moved on rails 6 and the filter device 20 is taken out. The regeneration of Al metal and Mg metal on an industrial scale is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filtration device for industrial-scale recycling (including refining) of metal scrap, which is particularly advantageous for metals such as aluminum and magnesium.

Reporter: For example, the amount of recycled metal cans, which are collected as scrap and reused after being sold on the market, is increasing year by year, and this type of recycling is important for energy conservation and resource replenishment. It is beginning to play a role. At the same time, it is also important to preferably regenerate aluminum-based metal return material produced in various processes. This kind of recycling is not limited to aluminum metals;
The same applies to magnesium-based metals and other various metals.

For example, the typical object to be removed in the recycling of aluminum-based metal scrap is iron, and conventional methods for removing Fe include the mercury method, magnesium method, zinc method, segregation utilization method, or Japanese Patent Publication No. 57-2134. As disclosed in issue A.
A method is known in which an Al-Mn-Fe intermetallic compound is generated by introducing I-Mn alloy particles into a molten metal, and the intermetallic compound is removed. A filtration method is also known as a method for removing other impurities including Fe. On the other hand, as a method for recycling magnesium-based metal scrap, a layer of flux is formed at the bottom of a fixed processing furnace, and the molten metal to be recycled is introduced into the processing furnace, and inclusions such as oxides are removed by passing through the flux layer. Absorption method (U.S. Pat. No. 438,593)
(see Japanese Patent Publication No. 18063), or a method in which oxides and the like are removed by filtration in the same manner as in the case of aluminum-based metals without using flux (see Japanese Patent Publication No. 18063/1983).

However, none of these treatment methods have been fully realized on an industrial scale.The main reason for this is that the efficiency is low when the proposed technology is used in actual operation, and the yield is low. This is because the drawbacks of being bad have not been resolved.

For example, in the case of magnesium-based metal scraps and whelks, recycling treatment using flux makes it difficult to completely remove the flux itself, so it may be adversely affected by the flux itself, or the yield may deteriorate due to the metal being carried away by the flux. Inevitable. In addition, scraps collected from outdoor storage items and fabrics have oil and large amounts of dust attached to them, making recycling processing very troublesome and requiring a large amount of flux, further deteriorating recycling yields and reducing economic efficiency. This is because it will be difficult to make a profit.

Further, in the treatment method of filtration without using flux, no apparatus has been provided that can sufficiently solve problems such as productivity, operability, and economic efficiency.

The purpose of this invention is to improve the yield, improve processing workability, and reduce metal handling loss and energy consumption in order to recycle metal scrap such as aluminum-based metals and magnesium-based metals on an industrial scale. An object of the present invention is to provide a regeneration filtration device with improved loss.

The filtration device for recycling metal scrap according to the present invention includes a heating means for melting the metal scrap input for filtration or for maintaining the molten metal supplied after being melted in advance at a temperature higher than the solidification temperature. a lower tank having a heating means, a filter device interposed between the upper tank and the lower tank, a temperature control device for the reheating means, and a pressurizing means connected to the upper tank. and/or a decompression means connected to the lower tank, a lifting device for the upper tank and/or a conveying device for the lower tank.

In the embodiment shown in FIG. 1, reference numeral 1 denotes an upper tank that can be an electric furnace equipped with a plurality of divided heating coils IA.

Moreover, the code|symbol 2 is a lower tank which can be made into an electric furnace similarly equipped with 2 A of heating coils. The upper tank 1 and the lower tank 2 are capable of housing and holding a crucible 3 and a crucible 4 therein, respectively. That is, as shown in the figure, the upper tank 1 is connected to the lower end flange 3 of the crucible 3.
A is fixed with bolts and held, while a crucible 4 is inserted into the inner space of the lower tank 2 from above and placed thereon. The crucible 3 has a cylindrical shape with both ends open, and the crucible 4 has a bottomed cylindrical shape with an upper end open. These crucibles are made of graphite and cast iron.

However, various inner surfaces can be lined with refractory bricks to form an integral structure.

The lower tank 2 is equipped with wheels 5 and can be moved along rails 6 provided on the floor of the metal scrap recycling facility. It is possible to provide an appropriate drive device for moving the lower tank 2, and to automatically control the operation of this drive device after the filtration is completed. Here, we will use a hand-held mobile type. On the other hand, the upper tank 1 can be lifted/lowered by suitable lifting means (not shown) via a chain 7, for example, as shown. Similar to the movement control of the lower tank 2 described above, the lifting/lowering by the lifting means can be automatically controlled according to the positioning of the lower tank 2 and the completion of filtration. A guide rod 30 is provided to guide the raising and lowering of the upper tank 1, and a slider 31 (fixed to the upper tank 1) is engaged with the guide rod 30.

Here, reference numeral 8 is a lid for closing the upper end opening of the crucible 3. Further, reference numeral 9 is a temperature sensor.

Further, the reference numeral 10 is an argon gas supply path, for example, to which a pressurized source is applied, which leads into the crucible 3 through the lid 8, and the reference numeral 11 is (
SF, gas + dry air). Further, the inside of the crucible 4 of the lower tank 2 is provided with a passage 12 for reducing the pressure.

Interposed between the upper tank 1 and the lower tank 2 is a filter device, generally indicated by the reference numeral 2°. This filter device 2
0 is constructed with a filter holder 21 made of the same material (graphite or cast iron) as the crucible 3.4, and a filter 22 replaceably attached to the filter holder 21. The filter 22 can be a ceramic filter or a sintered iron-based metal fiber filter. Furthermore, a filtration member capable of trapping particles can be optionally used, such as by placing ceramic fiber cloth or porous brick material on a perforated iron plate. Of course, the filter holder 21 can also be made of rolled steel plate for boilers, and the material is not limited.

Furthermore, if necessary, a heating means such as a heating wire may be embedded in the filter holder 21 to maintain the filter 22 at a predetermined temperature.

This filter device 20 can be positioned and placed on the upper end flange 4A of the crucible 4 in the lower tank 2, and the lower end flange 3A of the crucible 3 held in the upper tank 1 is placed above this. It is about to be placed. These abutment surfaces need to be in airtight contact for pressure filtration in which the inside of the crucible 3 is pressurized or vacuum filtration in which the inside of the crucible 4 is depressurized, as will be described later. For this purpose, a suitable gasket 23 is interposed as necessary.

In the regeneration apparatus having such a configuration, metal scrap to be regenerated is put into the crucible 3 of the upper tank 1, or already molten metal is supplied. If the scrap is to be thrown in as it is, the upper tank 1 needs to be equipped with heating means that generates enough heat to melt the scrap. In any case, it is preferable that the crucible 3 of the upper tank 1 be preheated. For example, when refining and regenerating aluminum-based metals, impurities are produced at a temperature lower than the temperature of the molten metal (approximately 700°C or higher) when it is supplied as a molten metal, and the impurity is near the melt temperature determined based on the liquidus temperature. It is appropriate to retain it so that filtration can be carried out. The typical composition of magnesium die-casting material is 90% Mg, 9% /lSQ, 5-0
．． 9% by weight of Zn, and the balance, and the solidification temperature is 59% by weight.
Since the temperature is around 0°C, in order to remove impurities mainly composed of oxides, it is generally appropriate to maintain the molten metal temperature around 650°C to enable filtration. In this way, the preheating temperature and the filtration temperature are preferably selected depending on the metal to be treated. For example, if the filtration temperature is lower than a predetermined temperature, the amount of filtration residue will increase and the yield will deteriorate, while if it becomes higher, the oxidation of the molten metal will become more intense and the energy cost will increase.

Moreover, when supplying molten scrap to the crucible 3, 1. the scrap is melted in a separate melting furnace. When handling molten magnesium in these series of operations, i.e. when adding magnesium to aluminum scrap to refine and regenerate it, or when regenerating magnesium scrap alone, oxidation should be prevented using (SF, gas + dry air). . That is, according to the present invention, inclusions mixed in the molten metal are intended to be removed by filtration, and therefore refining using ordinary flux is not required.

If the molten scrap to be supplied is, for example, magnesium-based metal, it is well stirred in an atmosphere of SF, gas + dry air in a temperature range of approximately 700°C to 720°C to prevent oxidation, and the entire amount as much as possible can be supplied to the crucible 3. It is preferable to do this in order to improve the yield. From the viewpoint of productivity, it is preferable that the temperature of the scrap molten metal supplied to the crucible 3 is lowered to around the filtration temperature suitable for each metal in as short a time as possible. According to experiments, when crucible 3 is preheated to about 600°C and 10 kg of molten magnesium metal at 700°C to 720°C is supplied, the temperature can be lowered to the target temperature of 650°C in about 10 to 20 minutes. has been found.

After the temperature sensor 9 detects that the required filtration temperature has been reached, the inside of the crucible 3 is pressurized by the pressure source application gas supply path 10 or the crucible 4 is pressurized through the pressure reduction suction path 12.
Reduce the pressure inside. It is also possible to use pressurization and vacuum in combination.

After the filtration is completed, the upper tank 1 is lifted up by the lifting device,
Next, after moving the lower tank 2, the filter device 20 is taken out. Residues removed by filtration remain on filter 22. These residues are processed together with the filter W20.

The filtered molten metal thus received in the lower tank 2 is taken out from the crucible 4. For this purpose, any method such as a manual pumping method, a vacuum suction method, a pressurized pumping method, or the use of a tapped hole can be used. In this way, recycled molten metal is obtained.

Like magnesium-based molten metal (if the molten metal is easily oxidized,
When melting scrap or pre-melted molten metal, the upper tank 1
When filtering by pouring into the crucible 3, SF is added to the crucible 3.
, is supplied through the supply path 11 to suppress oxidation.

SF6 gas is also supplied into the crucible 4 of the lower tank 2 after filtration.

Similarly, it is preferable to spray the same S F h gas onto the filter device 20 in order to prevent oxidation of the residue.

Of course, other gases can also be used.

FIG. 2 shows a state in which the filter device shown in FIG. 1 is assembled into an exterior casing 40. Here, the upper tank 1 and the lower tank 2 are shown to be tightened by a clamp 41. However, this clamp 41 can be omitted depending on the weight of the upper tank 1. Further, although a sprocket 42 is shown on the top of the exterior and a structure is shown in which the upper tank 1 is raised and lowered by a chain (not shown), it is of course possible to use a structure other than this.

In the apparatus shown in FIG. 1 as described above, the crucible 3.4 is made of graphite, and the graphite filter holder 21 is made of alumina and has a diameter of 1QQmm x thickness of 1Q.
An aluminum-based metal scrap recycling test was conducted using a filter device 20 equipped with a filter 22 having an average pore diameter of 170 μm.

The sample scrap weighed 10 g, was put into the crucible 3 of the upper tank 1 as it was, and was melted at 750°C. After complete melting, the temperature was lowered to 605° C. in approximately 1 hour. Thereafter, the inside of the crucible 3 was pressurized to 0.5 atm gauge pressure with nitrogen gas, and filtration was started. The results of composition measurements conducted to examine the regeneration effect after the completion of filtration are shown below.

MJiJIL Iu! ajIL 1 minute weight (kg)
10 8,5 1 0.5 composition S
i 10.3% 9.5% 9. '8% -F
e 1.5% 0.72% 8.7% -Mn
1.5% 0.35% 9.8% -AI
Remaining Remaining Remaining -S MML In contrast to Example 1, the crucible 3.4 and the filter holder 21 were both made of cast iron, the average pore diameter of the filter was 220 IIm, and 7.5 kg of scrap was
Adding 2.5 kg of 9.9% pure magnesium, 72
After melting at 0° C., the temperature was lowered to 540° C. in 1 hour, and then the pressure of the crucible 4 in the lower tank 2 was reduced to 0.5 atm and filtered.

In addition, 2% SF and gas and dry air were supplied as described above to prevent oxidation. The composition measured after completion of filtration is shown below.

” L Sample Plate Sosei Returned Ori Ritate weight (kg)
2.5 7.5 B, 5 1.5 Neglected composition Si0.6% 0.26% --Fe
1, 53% 0.09% 7% -Cu
O,10% 0.08% --Mn O,8
8% 0.09% 3% -Zn 0.04%
0.03% --Mg 1.3% 30%
--In Example 2, the amount of scrap was 7.0 kg/99.9%
The same procedure as in Example 2 was conducted except that 3.0 kg of pure magnesium was used and the temperature was lowered to 540° C. 1 hour after melting. The results are shown below.

Mg wipe weight (kg) 3.0 ? , 0B. 2
1.60.2 Composition SiO, 52% 0.5
2% --Fe 1.18% 0.05%
5% -CuO, 44% 0.29% --
MnO, 99% 0.08% 3.5%-Z
n O, 3% 0゜21% --Mg
0.94% 32% -- As a result, it was found that the filtration device according to the present invention can regenerate aluminum metal scrap with a sufficiently high degree of purification, and has good workability.

Randomly collect 10 magnesium die-casting scraps from Shorougodofu.
After removing adhering oil, dust, etc. with a wire brush, it was melted in a crucible at 700°C. At this time,
In order to prevent oxidation of the molten metal, (SF, gas + dry air) was filled into the crucible.

After thoroughly stirring this molten metal, the entire amount was put into a cast iron crucible 3. Crucible 3 and filter holder are prepared in advance.
It was preheated to 0°C. (SF gas + dry air) was supplied to the upper tank 1 through the gas supply path 11, and at the same time a small amount of (SF gas + dry air) was supplied to the lower tank 2. When the temperature of the molten magnesium scrap input has dropped to 640°C (about 10 minutes later), the cast iron crucible 4 in the lower tank is heated to zero.
．． The pressure was reduced to 5 atm and filtration (the filter was made of alumina, with an average pore size of 200 μm) was started. The regeneration effect of the magnesium die-casting scrap sample obtained by this operation is shown in terms of composition as follows.

LE! rX 4 Excessive 1 Graduation Weight of ball tray (kg)
9.6 8.8 0.7 0゜1 composition
SiO,21% 0.23%FeO,03
% 0.01% or less Cu O, 06% 0.0
6%MnO, 23% 0.20%AI
5.8% 5.9%ZnO,4
2% 0.45% Mg Remaining Remaining S11 Regeneration was performed on other samples in the same manner as described above. The filter used was made of mullite, with an average pore size of 2.
It was 00 μm. This regeneration effect is shown in terms of composition as follows.

Sample 1 Filtration rate 1 Spillage Tamadarai weight (kg) 9.4 B, 5 0.9
0 composition Si 0.05% or less 0.05% or less Fe O, 01% 0.01%Cu
O,06% 0.07%Mn 0.15%
0.13% AI 8.7% 8.8
%ZnO, 62% 0.65%Mg
Remaining Remaining As described above, inclusions could be sufficiently removed from magnesium-based metal scrap by filtration, as in the case of aluminum-based metal scrap.

Furthermore, cast bodies were formed from the recycled magnesium molten metal and the scrap molten metal before recycling, and these were used to test the cleanliness of the molten metal due to inclusions at the fracture surface and to test the oxygen content by fast neutron activation analysis. carried out. As a result, the cleanliness of the molten metal has been significantly improved (the number of inclusions in the scrap molten metal is 1000 inclusions/7.0cm", compared to 1 inclusion/7.0cm" in the recycled molten metal), and the oxygen content of the scrap molten metal has been significantly improved. It was confirmed that the recycled molten metal had a reduction of 0.016% compared to 0.10% in the recycled molten metal.

]yI and Results■ It will now be possible to recycle scrap aluminum and magnesium metals on an industrial scale, which has been proposed only experimentally in the past.

■ In particular, magnesium scrap in cars can be recycled by processing without using flux.

■ A filter device is interposed between the upper tank and the lower tank,
It has excellent workability because various parts can be moved and operated easily to facilitate replacement of the filter device.

■ The weight of the molten metal can be utilized to the maximum for filtration, and furthermore, the oxidation inhibitor gas can be used for forced filtration. Particularly at the start of filtration, the molten metal does not wet the filter and is difficult to filter, but this can be improved by forced filtration.

(2) In other words, forced filtration allows the pore size of the filter to be made smaller without sacrificing productivity, and the regeneration effect can be greatly enhanced.

■ Automation can be easily achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the basic structure of a filtration device for recycling metal scrap according to the present invention. FIG. 2 is a longitudinal cross-sectional view showing the filtration device of FIG. 1 assembled into an exterior case. 1... Upper tank IA... Heating coil 2... Lower tank 2A... Heating coil 3.4... Crucible 5... Wheel 6... Rail 7... Chain 8... Lid 9... Temperature sensor 10.1 Gas supply passage 12... Decompression passage 20... Filter device 21... Filter holder 22... Filter 30...・Guide rod 31...Slider 40...Exterior 41...Clamp 42...Subrocket

Claims (2)

[Claims] (1) an upper tank having a heating means for melting the metal scrap thrown in for filtration or for maintaining a pre-melted molten metal supplied at a predetermined temperature; and a lower tank having a heating means; a filter device interposed between the upper tank and the lower tank; a temperature control device for both heating means;
a pressurizing means connected to the upper tank and/or a depressurizing means connected to the lower tank; a lifting device for the upper tank;
Alternatively, a filtration device for recycling light metal scrap, characterized in that it is configured to include a conveying device for the lower tank. (2) The light metal scrap according to claim 1, wherein the filter device is constructed by attaching a filter replaceably to a holder member interposed between the upper tank and the lower tank. Filtration device for regeneration.