JPS58125341A - Forming method of molten metal for casting utilizing thermit reaction - Google Patents

Abstract

PURPOSE:To obtain desired molten metal for castings which is removed of Al in a short time by blowing a gas such as are or oxygen into the molten metal formed by thermit reaction then adding desired element groups. CONSTITUTION:Thermit agents are packed in a reaction vessel A, and are caused to react, whereby molten metal is formed. After the molten metal is charged into a crucible B, a gas such as air, oxygen, nitrogen or argon is blown into the molten metal through a porous plug 6 to convert the Al contained in the molten metal to Al2O3. Thereafter, CaO, etc. are added to the molten metal to form the slag of Al2O3 and to remove Al which is a harmful element from the molten metal. Control element groups are added to the molten metal removed of the Al. Thus, the desired molten metal for castings is obtained in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing AI, which is a harmful element, from a molten metal obtained by reacting a thermite agent, and further adding necessary elements to produce a molten metal for desired casting. It is something.

The thermite reaction is originally a chemical reaction in which a metal oxide is deoxidized by A1, and is conventionally known as a metal welding method that utilizes the high temperature heat generated during this reaction. In that case, there are various types of thermite used to suit the material of the metal to be welded, such as mild steel thermite, cast iron thermite, wear-resistant thermite, and rail welding thermite. It is also well known. Among these, the following example is introduced as the chemical composition of the metal produced by the reaction of thermite agents for cast iron in Japan (``Fusion Welding and Fusion Cut'', published by Nikkan Kogyo Shimbun in 1962).

CSi Mn AI P 5T
C-10131550,400,400,020,01
TC-23,551,850,25'0.35 0.
02 0.01 This is Al for iron scale 3-4
In addition to the basic composition of thermite, which is a proportion of C*
This shows that Si.Mn was added in an appropriate amount. This suggests that the molten metal produced by the thermite reaction can be used as a molten metal for casting by adjusting its composition.

The present invention has been made with this point in mind, and its purpose is to meet the current demands for resource and energy conservation.

In other words, since the method for producing molten casting metal according to the present invention uses iron oxide and scrap iron as its main materials, it utilizes materials that cannot be used in conventional casting methods, and furthermore, the melting energy is Since the heat of chemical reaction is used, the melting energy of conventional casting methods is not required.

In particular, current energy is becoming more expensive due to soaring electricity costs, and for example, the cost of melting in an electric furnace is double that of casting, and it is thought that this trend will continue step by step in the future. However, this fact has become an economical stage device that makes it possible to realize the present invention, which converts the molten metal produced by the thermite reaction, which was conventionally considered to be expensive, from welding to casting. -ing

When considering the implementation of the present invention against the background of these circumstances, it is necessary to make the following considerations regarding the reaction of the thermite agent.

(1) Since the thermite reaction is a reaction in which a metal oxide is deoxidized by AI, it is unavoidable that a suitable amount of AI remains in the resulting molten metal. This is shown as 0.35% to 0.140% in the chemical composition table of thermite produced in Japan for cast iron mentioned above, but this residual AI mainly uses this molten metal as the source water for spheroidal graphite cast iron. This is particularly inconvenient in some cases. Spheroidal graphite cast iron is a cast iron that adds toughness to cast iron by spheroidizing the flaky graphite in gray cast iron, and it is a new cast iron that has been around 30 years since the technology was patented.
With the expiration of its patent rights in 1966, production increased rapidly, and now the annual production volume has continued to increase year after year, and it is now on the verge of occupying the mainstream of cast iron and castings. This spheroidal graphite cast iron is produced by adding Mg alloy to the base molten metal of gray cast iron to make flaky graphite in the molten metal spheroidized, and this method is most widely adopted, and the above-mentioned expired patent applies to this method. When spheroidizing the graphite of this spheroidal graphite cast iron, there are elements in the molten metal whose presence inhibits the spheroidization of graphite, and the names and inhibition limits of these elements are as follows ( Published by Agnesha in 1964 "On-site Casting") 0
(珪-'KL乍食燵ζ?閘（）Element AI Ti
Cu Sn Se As Nb Ta-'
c (D other limit quantity 0.020.042.00.10.0
50.050.150.2 or higher (and especially A1
is an inhibiting element with a limit amount of 0.02%. In other words, the content of AI in the grooves and hot water produced by the Termi-Soto reaction is 0.35% to 0.4% as mentioned above, which means that the content is about 20 times the limit amount, and as it is. This makes it inconvenient to use it as a source water for spheroidal graphite cast iron. Furthermore, when used in gray cast iron, Al is an element that promotes graphitization, so when it is contained in the molten gray cast iron, it tends to turn the base into ferrite, making it difficult to cast high-grade gray cast iron with a pearlite base that has high hardness and high tensile strength. In some cases, the presence of AI is undesirable. Therefore, when the molten metal produced by the thermite reaction is used for casting molten metal, it is necessary to remove an appropriate amount of this A1 in advance.

(2) Thermite reaction is iron scale 3-4: A11
In the case of a basic formulation with a ratio of , the reaction temperature is 2000℃~
The temperature is 2400°C, and the molten metal production ratio is about 50%.

On the other hand, in the case of the current casting method, the temperature of the hot water released from the furnace is approximately 15
00°C, it is necessary to take this tapping temperature into consideration when formulating the thermite agent that determines the reaction temperature. Therefore, the thermite agent increases iron scale and decreases the proportion of A4 compared to the basic formulation, and changes the reaction temperature and de-A1
It is preferable to adjust the temperature of the molten metal after treatment to be appropriate, and at the same time improve the production ratio of the molten metal and reduce the amount of residual A1 in the molten metal.

The implementation of the present invention with consideration of the above two points will be explained below with reference to the drawings. Figure 1 shows an embodiment of the method for producing molten casting metal according to the present invention. Main body with a frame lined with refractory material (1)
It consists of an iron lid (2), which is filled with thermite agent whose composition has been decided based on the above-mentioned consideration 2, and is ignited with fireworks to cause a reaction, but thermite reaction is a very violent reaction. After ignition, the top of the container body (]) is covered with a lid (3) with an air hole (3) in order to prevent the reactants from scattering.
2). When the reaction is completed, the container body (1)
The molten metal accumulates in the lower part of the crucible and a slurry is formed in the upper part, so the molten metal is injected from the outflow nozzle (4) into the crucible B), but the timing of the injection is determined by the iron plate on the nozzle (4), which is melted by the reaction heat. The thickness shall be set as shown in (5). The crucible fBl is an iron cylindrical outer frame lined with refractory material, and has an inlet (7) with a porous plug (6) attached to the bottom, and a gas pipe (8). ) and legs (
It has a structure that allows it to be placed on a flat surface by means of lυ, and can be tilted when necessary using both sides and a handle.

The de-AI treatment of the molten metal and the addition of the adjusting element group are carried out in the crucible fBi.
After the molten metal is injected into the molten metal, various gases are blown into the molten metal, singly or in a mixture, from the pipe (8) via the porous plug (6). becomes as follows. The chemical components other than A1 of the molten metal in container A) to be subjected to A1 removal treatment are as follows.

C*Si*Mn 0.05%-0,1
0%P -3-Cr -Ni Fist Mg 0.0
5% or lessThe amount of elements other than AI in such a component is extremely small, so there is no need to pay special attention to changes in elements due to gas injection.
When processing is performed, ρ is an advantage. As shown in the table below, A1 is an element with the second strongest affinity for oxygen after Ca--Mg among various elements, so it is also advantageous.

(Comparison of the bonding strength of various elements with oxygen) Element content Standard free energy of formation Iron (Fe)
Approximately 75 chromium (Cr)
■t.

Manganese (Mn) 128 Silicon (Si)
138 Titanium (Ti) 150 Aluminum (AI) 185 Magnesium (Mg) 195 Calcium (C
a) 225 (``Materials of Cast Iron'', published by Corona Publishing, 1960) As mentioned above, A1 has a strong binding force with oxygen, so it has been conventionally used as a deoxidizing agent in molten metal. When trying to remove oxygen from the molten metal, A
Alumina (AI) is created by adding I to the molten metal and combining it with oxygen.
□03) This is a deoxidation method that generates and removes . The deoxidation method of the present invention reversely utilizes the characteristics of this AI and attempts to deoxidize it by blowing in oxygen.The principle is the same as the conventional deoxidation method, and therefore its effectiveness is also There is no difference in the bond between AI- and oxygen. Since this is a removal treatment of A1 having the above-mentioned characteristics, and the amount required to be treated is as small as 0.5% or less, the following gas blowing effect can be considered.

Type of gas Effect Oxygen Actively generates Al2O3 by combining with AI.

Air (1) Al2O3 is produced by the combination of oxygen in the air and AI.

(2) The surface of the molten metal is created by stirring the molten metal. When oxygen in the air and AI combine Increase opportunities to become A12o3.

Water in the air by mixing with nitrogen and air argon
The molten metal is stirred using a gas with a lower elemental content ratio, increasing the chances of A1 combining with oxygen in the air on the surface of the molten metal.

As mentioned above, when trying to convert 0.3% A1 in 1.000 kg of molten metal into Al2O3 for plywood, the required amount of oxygen is approximately 1.8 tt/, which is the same The amount of air required to obtain the effect is approximately 9,3-, but since oxygen also combines with Fe, it is necessary to check the amount of oxygen blown and to consider a simple deoxidation treatment after the A1 removal treatment. In addition, in the case of air blowing, the presence of hydrogen in the air may cause pinholes in the casting, so consideration must be given to reducing the hydrogen ratio due to mixing of air and other gases. Al2O3 in the molten metal generated by gas injection in this way is removed by adding powder such as CaO into the molten metal to turn it into slag, but the specific gravity of Al2O3 is 3°95-4.
．． Since it has a specific gravity smaller than that of 10 and Fe, it tends to float to the surface of the molten metal, which is advantageous. In this way, de-AI
If the adjustment elements are added when the treatment has progressed considerably, and at the same time the amount of air and oxygen is reduced and the gas is changed to a gas with increased amounts of argon, nitrogen, etc., the molten metal can be stirred by blowing without damaging the added elements. This is advantageous because it has the effect of promoting dissolution of the element group into the molten metal. This is particularly noticeable in the case of spheroidal graphite cast iron, which is subjected to graphite nodularization treatment by adding Mg alloy. The molten metal that has been subjected to the AI removal treatment and component adjustment is poured into the mold in this way.The temperature of the molten metal at this point needs to be maintained at approximately 1500°C, so the dermite reaction temperature in the reaction vessel is Of course, it is necessary to adjust the temperature back to the time of adjustment.

Figure 2 shows another embodiment of the method for producing molten casting metal according to the present invention. Lid (2)
A gas pipe (8) is connected to an inlet (7) in which a porous plug (6), which is a porous refractory, is embedded in the bottom or side refractory. A slag discharge port (9) is provided on the side surface of the main body (1) and is closed with an iron plate (5).
) is assumed to have a gear - and a 7% wheel →. When the reaction of the thermite agent in the container body (1) has subsided, the molten metal (B) is covered with fluid slag, so at an appropriate time, the slag discharge port (9) is When a refractory pipe (1) is inserted from the outside, the iron plate (5) whose thickness has been set in advance so that it becomes red hot due to the reaction heat is removed, and the pipe is dammed by the iron plate (5). The slag o mark that was used is 0 for refractory pipes.
0) to m groan 4 slag pool (1→).

The remaining slag on the molten metal surface from which a large amount of slag has been removed in this way is removed from the top of the main body (1) excluding the lid. At that point, de-A by gas according to the above-mentioned procedure.
While performing the I treatment, various elements are added to adjust the composition to obtain the desired molten casting metal.

The molten metal that has been adjusted in this manner to obtain the desired casting molten metal is then poured into the mold by tilting the container hole that has been moved to the top of the mold. If a drop in the temperature of the molten metal cannot be avoided during that time, it is desirable to make a large amount of molten casting metal in a large container A), and pour the molten metal frequently into a small ladle while maintaining the temperature in a holding furnace or the like.

By implementing the present invention as described above, it becomes possible to perform casting using inexpensive materials and without requiring conventional melting equipment and energy, but the following advantages can be calculated. .

In the case of conventional electric furnace melting, it takes about 2 hours for one melt to melt 1.5, but in the case of the present invention, it takes about 15 minutes to generate the same volume of molten metal and adjust the composition. Because all you need is a mold, you can prepare the required amount of molten metal in a short time, which shortens work time and increases production, resulting in a reduction in the overall cost of castings. It becomes.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a combination of a reaction vessel and a crucible in an embodiment of the method for producing molten casting metal according to the present invention, and Fig. 2 is a sectional view of the reaction vessel showing another embodiment of the method for producing molten casting metal according to the present invention. Yes. Code explanation (A)... Reaction vessel FB+... Crucible (1).
... Container body (2) ... Lid (3) ... Air hole in the lid (4) ... Outflow nozzle (5) ... Iron plate (6)
... Porous plug (7) ... Inlet (8)
・・Gas pipe (9)・・Slag discharge port θ0)・
... Fireproof pipe (11) ... Leg (121 ... Molten metal (13) ... Slag α4) ... Slag sump. Patent applicant Masami Michihiro

Claims (4)

[Claims] (1) A method for producing molten metal for castings using a thermite reaction, which comprises adding a group of elements to the molten metal produced by reacting a thermite agent to adjust the composition to the composition required for a desired casting. (2) The method for producing molten metal for castings according to claim 1, wherein the molten metal produced by reacting a thermite agent in a reaction vessel is injected into a crucible, and gas is blown into the molten metal in the crucible. (3) The method for producing molten metal for castings according to claim 1, wherein gas is directly blown into the molten metal produced by reacting a thermite agent in the reaction vessel. (4) A thermite reaction vessel for producing molten casting metal according to claim 3, which has a gas inlet connected to a porous plug which is a porous refractory.