The present invention relates to a device and a method for continuously removing impurities from molten metal.
Conventionally, productization from molten metal having electrical conductivity (conductivity), that is, non-ferrous molten metal (e.g., Al, Cu, Zn, or Si, alloy including at least two of these, Mg alloy, or the like) or molten metal other than non-ferrous molten metal includes, for example, steps of dissolving raw materials, adjusting components, removing impurities mixed in molten metal, and molding. Removal of impurities is generally referred to as purification of molten metal, and, for example, a ceramic filter is used therefor.
However, since an impurity removal method using a filter is, of course, a filtration method, clogging is likely to occur. Therefore, there is a problem such that the workability is deteriorated and the running cost is increased.
In other words, in a case of a filter type, how large the mesh is set to is actually an important point. In order to remove not only large impurities but also fine impurities, the mesh must be fine. However, if the mesh is made fine, clogging is more likely to occur. For example, clogging may occur instantaneously, and production may stop.
Thus, conventionally, flux is previously introduced into the molten metal prior to removal with a filter. By such introduction, impurities are changed into substances having a large particle size. As a result, it becomes possible to remove impurities while keeping the mesh large to some extent, and it is possible to increase the removal efficiency (trap efficiency) of the filter. However, it is not preferable to introduce flux into the molten metal in terms of product quality in many cases.
As described above, according to a conventional method, it is actually impossible to continuously produce products without stopping production of products while removing impurities, including fine impurities, from molten metal.
The present invention has been made in view of such circumstances, and it is an object thereof to provide a device and a method for continuously removing impurities for enabling continuous manufacture of products while removing impurities from non-ferrous metal or other molten metal containing impurities with high accuracy.
An embodiment of the present invention is
a device for continuously removing impurities from molten metal, which sends electrically conductive molten metal to a metal product manufacturing device in a next stage, the device including:
a molten metal flow path body having a molten metal flow path for flowing electrically conductive molten metal that has flown from outside toward the metal product manufacturing device;
an inlet-side closed end plate and an outlet-side closed end plate that are provided in the molten metal flow path body so as to partition a front and a rear of the molten metal flow path and form an impurity removal space;
an electrode device composed of an inlet-side electrode and an outlet-side electrode that are provided in the impurity removal space, face each other in a longitudinal direction in which molten metal flows, and can be put into electrical contact with molten metal in the impurity removal space; and
a magnetic field device composed of a pair of permanent magnets that are provided outside the molten metal flow path forming body, face each other in a width direction intersecting the longitudinal direction, sandwich the impurity removal space of the molten metal flow path forming body in the width direction, have opposite poles facing each other, and can form a magnetic field in molten metal in the impurity removal space,
in which the electrode device and the magnetic field device constitute an urging device that can apply a Lorentz force downward to molten metal in the impurity removal space so as to increase a density of the molten metal and cause impurities in the molten metal to rise up to a surface of the molten metal.
Furthermore, an embodiment of the present invention is
a continuous impurity removal method for removing impurities from molten metal in sending electrically conductive molten metal to a metal product manufacturing device in a next stage, the method including:
preparing a molten metal flow path body having a molten metal flow path for flowing electrically conductive molten metal that has flown from outside toward the metal product manufacturing device;
providing an inlet-side closed end plate and an outlet-side closed end plate in the molten metal flow path body so as to partition a front and a rear of the molten metal flow path and form an impurity removal space;
providing, in the impurity removal space, an electrode device composed of an inlet-side electrode and an outlet-side electrode that face each other in a longitudinal direction in which molten metal flows and can be put into electrical contact with molten metal in the impurity removal space;
providing, outside the molten metal flow path forming body, a magnetic field device composed of a pair of permanent magnets that face each other in a width direction intersecting the longitudinal direction, sandwich the impurity removal space of the molten metal flow path forming body in the width direction, have opposite poles facing each other, and can form a magnetic field in molten metal in the impurity removal space; and
causing an urging device composed of the electrode device and the magnetic field device to apply a Lorentz force downward to molten metal in the impurity removal space so as to increase a density of the molten metal and cause impurities in the molten metal to rise up to a surface of the molten metal.
Furthermore, an embodiment of the present invention is
a device for continuously removing impurities from molten metal, which sends electrically conductive molten metal to a metal product manufacturing device in a next stage, the device including:
a molten metal flow path body having a molten metal flow path for flowing electrically conductive molten metal that has flown from outside toward the metal product manufacturing device;
an inlet-side closed end plate and an outlet-side closed end plate that are provided in the molten metal flow path body so as to partition a front and a rear of the molten metal flow path and form an impurity removal space;
an electrode device composed of an inlet-side electrode and an outlet-side electrode that are provided in the impurity removal space, face each other in a longitudinal direction in which molten metal flows, and can be put into electrical contact with molten metal in the impurity removal space; and
a magnetic field device composed of a pair of permanent magnets that are provided outside the molten metal flow path forming body, face each other in a width direction intersecting the longitudinal direction, sandwich the impurity removal space of the molten metal flow path forming body in the width direction, have opposite poles facing each other, and can form a magnetic field in molten metal in the impurity removal space,
in which the outlet-side electrode is provided in a floating state in the impurity removal space so that a first gap opened vertically is formed between the outlet-side electrode and a bottom surface of the molten metal flow path forming body and a second gap opened in the longitudinal direction is formed between the outlet-side electrode and the outlet-side closed end plate, and
the electrode device and the magnetic field device constitute an urging device that can apply a Lorentz force downward to molten metal in the impurity removal space so as to increase a density of the molten metal and cause impurities in the molten metal to rise up to a surface of the molten metal, and can send molten metal on an inner side than the outlet-side electrode in the impurity removal space through the first gap to the second gap.
Furthermore, an embodiment of the present invention is
a continuous impurity removal method for removing impurities from molten metal in sending electrically conductive molten metal to a metal product manufacturing device in a next stage, the method including:
preparing a molten metal flow path body having a molten metal flow path for flowing electrically conductive molten metal that has flown from outside toward the metal product manufacturing device;
providing an inlet-side closed end plate and an outlet-side closed end plate in the molten metal flow path body so as to partition a front and a rear of the molten metal flow path and form an impurity removal space;
providing, in the impurity removal space, an electrode device composed of an inlet-side electrode and an outlet-side electrode that face each other in a longitudinal direction in which molten metal flows and can be put into electrical contact with molten metal in the impurity removal space;
providing, outside the molten metal flow path forming body, a magnetic field device composed of a pair of permanent magnets that face each other in a width direction intersecting the longitudinal direction, sandwich the impurity removal space of the molten metal flow path forming body in the width direction, have opposite poles facing each other, and can form a magnetic field in molten metal in the impurity removal space;
providing the outlet-side electrode in a floating state in the impurity removal space so that a first gap opened vertically is formed between the outlet-side electrode and a bottom surface of the molten metal flow path forming body and a second gap opened in the longitudinal direction is formed between the outlet-side electrode and the outlet-side closed end plate; and
causing an urging device composed of the electrode device and the magnetic field device to apply a Lorentz force downward to molten metal in the impurity removal space so as to increase a density of the molten metal and cause impurities in the molten metal to rise up to a surface of the molten metal, and send molten metal on an inner side than the outlet-side electrode through the first gap to the second gap.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In
More specifically,
The melting furnace 200 is a general-purpose tilting type melting furnace as described above. That is, the melting furnace 200 includes a container-shaped melting furnace main body 1 having an opening 2 at the top. A spout 3 for the molten metal M is formed at a side wall on the front side (left side in the figure) of the tilting type melting furnace main body 1. A general-purpose gas burner 4 is attached to a rear side wall. The raw material of the electrically conductive metal introduced from the opening 2 is heated by the gas burner 4 to be molten metal M and is housed in the melting furnace main body 1.
The impurity removing device 100 that receives the molten metal M from the melting furnace 200 is configured to have a function as a so-called gutter that allows the received molten metal M flow from right to left in
That is, as can be seen particularly from
As can be seen from
As can be seen from
The outlet-side closed end plate 11 can be configured such that the height thereof can be adjusted. Arbitral configuration configured such that the height thereof can be adjusted can be employed. For example, as can be seen from
The inlet-side electrode 13a in the electrode device 13 is provided in close contact with the inlet-side closed end plate 8, and the outlet-side electrode 13b is spaced from the outlet-side closed end plate 11 with a gap (second gap) G2 in the longitudinal direction and is provided in a floating state of floating with a gap (first gap) G1 in the depth direction. As a result, the molten metal M flows through the gaps G1 and G2, flows over the outlet-side closed end plate 11, or so-called overflows, and flows out from the main flow path 8 through an outflow auxiliary plate 7B toward the mold 300 as will be described later.
A power supply 16 is connected between the pair of electrodes 13a and 13b in the electrode device 13. This power supply 16 is configured to be able to pass an alternating current as well as a direct current. Furthermore, it is configured to switch the polarity of a direct current.
The magnetic field device 12 is provided on both right and left sides of the gutter main body 10 as can be seen from
Next, the operation of the embodiment of the present invention will be described.
As can be seen from
In this main flow path 14, the lines of magnetic force ML and the current I intersect each other as can be seen from
Therefore, in a state in which the Lorentz force f is generated, impurities IM in the molten metal M rise in the molten metal M and reach the liquid level. That is, impurities IM tend to settle in the molten metal M by its own weight. Moreover, a buoyancy due to the molten metal M acts on impurities IM. Thus, when the density of the molten metal M increases, a large buoyancy acts on impurities IM in the molten metal M. Therefore, impurities IM rise or fall according to a difference between the buoyancy and the settlement force. Thus, by setting the Lorentz force f to an expected value, the buoyancy becomes larger than the settlement force, and impurities IM rise in the molten metal M and reach the vicinity of the liquid surface. This operation is continuously performed in the process of flow of the molten metal M through the main flow path 14.
In this way, impurities IM rise up to the vicinity of the surface of the molten metal M. Impurities IM that have risen up are automatically or artificially discharged to an impurity receiver 40 via the impurity removing plate 7C as can be seen from
Moreover, in the gutter main body 10, the molten metal M is pushed down by application of pressure as illustrated in
The above-described fact that application of the Lorentz force f can cause impurities IM in the molten metal M to rise in the molten metal M will be described below in detail.
The magnetic field strength in the molten metal M in
F=fg+fm
Here, since the horizontal area A of the gutter main body 10 is A=l×a (l: the length of the gutter main body 10, a: the width of the gutter main body 10), the pressure P at a bottom portion of the gutter main body 10 is expressed as the following expression.
P=F/A Furthermore, assuming here that the current density between the pair of electrodes 13a and 13b is constant, the Lorentz force f becomes zero at the surface of the molten metal, and I×B×l (N) at a bottom portion. Thus, the pressure is highest at a bottom portion. This state is illustrated in
Furthermore, the apparent density of the molten metal M affected by two influences of the Lorentz force f and the gravity is denoted by ρm, the density of mixed impurity particles is denoted by ρs, and the particle size is denoted by V. The buoyancy fa received from the molten metal M and the force fg due to the gravity simultaneously act on the impurity particles. At this time, assuming that the force received by the impurity particles is denoted by Fs, the following expression is satisfied.
Accordingly, the impurity particles move in the molten metal M as follows.
(a) ρm−ρs>0 Rise
(b) ρm−ρs<0 Settlement
(c) ρm−ρs=0 Floating
With the embodiment of the present invention described above, the following advantages can be obtained.
(1) Continuous purification of molten metal M is possible, which is consistent with a continuous casting method that has become a standard technology in the industry.
(2) Although the rise speed of impurities varies depending on the particle size, density, and the like of impurities, the residence time of the molten metal M in the gutter main body (sorting tank) may be increased by slowing down the flow speed or lengthening the gutter main body, for example, in the case of separating objects (having small particle size) having a low rise speed.
(3) Since the purification is neither physical nor mechanical, there is no need to replace a filter, which not only improves the work efficiency but also reduces costs.
(4) The specific gravity of the molten metal can be easily changed by changing the magnetic field strength or the current value, and an impurity removing operation can be performed according to the type of the molten metal M to be subjected to impurity removal.
Number | Date | Country | Kind |
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217-220376 | Nov 2017 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2018/031232 | Aug 2018 | US |
Child | 16865530 | US |