JPH07216523A - Dross removing filter - Google Patents

Abstract

PURPOSE:To effectively remove the dross in a zinc plating bath and to prepare an inexpensive filter capable of being used for a long time. CONSTITUTION:This filter is used to collect and remove the dross in a zinc plating bath and made of the ternary intermetallic compd. of the iron, aluminum and zinc constituting the dross. Consequently, the dross is collected not only by filtration but also adsorption, the filter is made bulky by the dross itself, hence clogging is never caused, and the filter is continuously used for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for removing dross in a galvanizing bath in a galvanizing apparatus.

[0002]

2. Description of the Related Art In a zinc plating bath of a plating apparatus widely used in a continuous plating line, iron eluted from strips and rolls arranged in the zinc plating bath, zinc as a plating material, and plating quality Aluminum and zinc, iron and aluminum, and further respective compounds (dross) of iron, aluminum and zinc which are mixed in for improvement are produced.

These dross are roughly classified into a bodom dross which is a compound of iron and zinc deposited on the bottom of the plating bath and a top dross which is a compound of iron and aluminum floating on the surface of the plating bath. Furthermore, in the plating bath, iron that has been eluted from the bottom dross and strips of the bottom dross that accumulates at the bottom of the plating bath reacts with aluminum mixed in the bath, and dross that is a combination of iron and aluminum is floating. is doing.

These dross, especially those floating in the galvanizing bath, have the disadvantage of adhering to the surface of the strip and degrading the quality of the plating, and the dross is a sink placed in the plating bath. As it adheres to the rolls and support rolls, the sink roll, which is an idle roll, slips and causes rotation failure, which causes scratches on the strip and pushes on the strip due to uneven dross adhesion. There is an inconvenience that the quality of the plating is remarkably deteriorated due to a flaw or the like.

Further, there is also the inconvenience that scratches, push marks and the like are similarly generated by the support roll.

When the sink roll is in a poor rotation state, it is necessary to stop the plating operation and replace the plating apparatus, which causes a disadvantage that production cost and maintenance cost increase due to reduction of operating time. .

Conventionally, in order to solve such inconvenience,
There is a means (Japanese Patent Laid-Open No. 63-140070) for filtering the zinc plating solution with a filter made of porous ceramics to capture and remove dross in the plating solution.

In the ceramic filter according to the above-mentioned technique, although the dross can be captured, it is necessary to frequently replace it with a new filter because it causes clogging in a relatively short time, and the filter is made of ceramic. Therefore, it is expensive and generally not reusable, and there is a disadvantage that extremely troublesome processing (Japanese Patent Laid-Open No. 3-104847) must be performed in order to reuse.

Therefore, with this technique, the production cost is inevitably increased due to the increase in maintenance cost, and
There is an inconvenience that a dangerous work such as replacement of a filter is required on a processing line during continuous production.

As a conventional technique for solving this inconvenience, a plating bath containing dross is passed through a filter made of a substance having an intermetallic compound of iron and aluminum or an intermetallic compound of iron and aluminum formed on the surface, There is a means for removing dross (JP-A-5-171383).

[0011]

However, although the above-mentioned prior art certainly works effectively for removing dross, since the growth and deposition of trapped dross is fast, the durability against filter clogging is high. However, there is a problem in that the dangerous work of replacing the filter cannot be eliminated on the processing line during continuous production.

In order to improve the durability against the clogging, if the mesh of the filter is increased in accordance with the growth and deposition rate of the captured dross, it is impossible to capture the dross having a small size, and the filter effect is lowered. There was a problem.

Further, it is not possible to inexpensively manufacture a filter having a mesh size of 100 to 500 μm by using an intermetallic compound of iron and aluminum, and therefore, it is possible to suppress an increase in production cost due to an increase in maintenance cost. , There was a problem that it could not be fully exerted.

Therefore, the present invention was devised to solve the above-mentioned problems in the prior art. The technical problem is to remove the dross without clogging, so that the dross in the galvanizing bath is eliminated. It is an object of the present invention to provide an inexpensive filter which can be effectively removed and continuously used for a long time.

[0015]

Means for Solving the Problems The means of the present invention for solving the above technical problems is a filter for trapping and removing dross in a zinc plating bath. It is composed of a material that is a ternary intermetallic compound of zinc and zinc.

It is convenient to construct the filter by an amorphous bottom dross in which a filter material composed of a ternary intermetallic compound of iron, aluminum and zinc is deposited and deposited on the bottom of a zinc-based hot-dip bath of iron-based material. is there.

It is effective to set the transmission gap size of the filter to 1 mm to 5 mm. When using an irregular shaped granular material that is an irregular bottom dross, the size of the permeation gap is a size slightly smaller than the granular material size. Therefore, if the granular material size that constitutes the filter is set to 1 mm to 7 mm, Transmission gap dimensions of 1 mm to 5 mm can be obtained. Here, the grain size refers to a size obtained by averaging the thickness, width and length of irregularly shaped grains.

[0018]

According to the research result of the dross generated in the galvanizing bath, the dross grows largely with the passage of time, and the dross grows at a temperature of about 460 ° C to 480 ° C, which is the temperature of the plating bath under normal production conditions. It was found that the relatively large dross (iron-aluminum-zinc system compound) crystals were in a solid state and that the iron-aluminum-zinc system compounds were easily bonded to each other.

FIGS. 4 and 5 are schematic views of electron microscope photographs of a state in which an iron-aluminum-zinc compound (dross) is bonded (condensed). The dross located in the central portion of FIG. 4 has a size of about 200 to 300 μm, and it can be observed from this figure that small dross are combined and gradually increasing. FIG. 5 is an enlarged view of the portion A of the dross shown in FIG. 4, and the state of the dross combined can be known in detail from this figure.

Due to the characteristics of the dross, when the zinc plating bath is filtered by a filter made of a material composed of the same or almost the same ternary intermetallic compound of iron, aluminum and zinc as the dross, the conventional so-called ordinary filtering action is performed. According to the above-mentioned research result that the dross has a property of easily binding to the intermetallic compound of the same system in addition to the trapping by the dross, the dross can be also trapped by the adsorption action.

For medium or small dross, a filter made of a material consisting of a ternary intermetallic compound of iron-aluminum-zinc has an excellent adsorption effect on dross, and this ternary intermetallic compound is used. C in the compound
When r, Mn, Si, Co, and Ni are contained in an amount of 0.1 to 1.0%, the bond with dross is more likely to proceed, and thus the adsorption action is further enhanced.

Therefore, in a filter for trapping and removing dross in a galvanizing bath, by constructing the filter with a material made of a ternary intermetallic compound of iron, aluminum and zinc which constitutes the dross, Not only the dross larger than the permeation gap size is captured by the filtering action which is the original function of the filter, but also the dross is removed by the adsorption action of the filter against the dross, so that the dross is captured with a high trapping efficiency.

The trapped dross grows into large grains by being combined with each other or with the filter, and this growth is
Since the particle size of the uppermost filter is increased more than narrowing the gaps between the granules, that is, it works to raise the filter in the filtering direction, there is always a gap between the granules sufficient for molten zinc to pass through. Therefore, the filter is hardly clogged, and the filter can be continuously used for a long time.

Since the filter is made of a material composed of a ternary intermetallic compound of iron, aluminum and zinc, the filter can be manufactured at a much lower cost than the conventional ceramics, especially for the plating bath. The cost effect is remarkable when the filter is composed of an irregular bottom dross that is deposited and settled on the bottom.

If the filter has a transmission gap size of 1 mm or less, clogging is faster in dross adhesion growth than in bulk growth in the filtering direction of the filter.
If clogging occurs at an early stage, and if the filter transmission gap size is 5 mm or more, even if the filter layer thickness is considerably increased, the amount of dross that passes through the filter without being trapped increases, and it is practical. Disappears.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a filter 1 according to the present invention. The filter 1 is formed of a ternary intermetallic compound of iron, aluminum and zinc to form a granular body 2 having a predetermined size range. The granular body 2 is housed in a container 3 in the shape of a bottomed cylinder made of a material that is not corroded by the galvanizing solution, for example, a bottomed cylindrical container 3, and the bottom of the container 3 is A plurality of holes 5 through which the cleaned zinc plating solution passes are formed.

The zinc plating solution to be filtered is in a laminar flow state,
The particles 2 are flown into the container 3 without being suspended and suspended, and filtration of dross is achieved, but the trapped dross is accumulated on the layer of the particles 2 in a state of growing in a particle shape.

Therefore, the replacement of the filter 1 can be carried out by changing the granular material 2
The thickness of the dross deposited on the layer is preferably used as a guide.

FIG. 2 shows another embodiment of the filter 1, in which a large number of holes 6 through which the zinc plating solution can freely pass are provided above the layer of the granular body 2 in the container 3 and galvanized. The galvanizing solution, which is configured by providing a flat plate-shaped lid 4 made of a material that is not corroded by the solution, is flown into the container 3 in a state where the momentum of the galvanizing solution is killed. No. 2 is agitated and suspended, and is dispersed substantially uniformly and flows down.

The lid 4 is arranged with a certain space between it and the layer of the granular body 2. The distance between the lid 4 and the layer of the granular body 2 is a standard for replacing the filter 1. It is set according to the thickness of the captured dross.

FIG. 3 shows an example of use of the filter 1. The container 3 provided with the filter 1 is provided in the plating bath 7 of the plating apparatus, and the zinc plating bath 14 is pumped from the bell mouth 15 by the pump 11. By supplying the box-shaped container 3 from the outlet of the pipe 12, the dross in the zinc plating bath 14 is captured by the filter 1 by the filtering action and the adsorption action, and only the cleaned zinc plating solution is plated bath. I am trying to put it back in 7.

By adjusting the height of the bell mouth 15, the bottom dross can be removed intensively or the removal ratio of the floating dross can be increased.

A well-known sink roll 9 and a pair of support rolls 10 are installed in the plating bath 7. The strip 8 runs under the guidance of these rolls 9 and 10, and the surface thereof is subjected to a galvanizing treatment. The partition wall 13 provided in the plating bath 7 keeps the zinc plating bath through which the strip 10 passes in a zinc plating bath 14 that is as clean as possible, and the outer frame for fixing the filter 1 is the zinc plating bath 14. It is made of ceramics and other materials that are not eroded.

When the galvanizing bath 14 was continuously circulated and filtered by the filter 1 during the operation of the hot dip coating line,
When the amount of iron dissolved in the galvanizing bath 14 and the amount of aluminum added, the bath temperature, etc. are in a stable steady state, the filter 1 can be continuously used without clogging for a long period of time. The iron concentration in the bath 14
No occurrence of surface defects due to iron-based dross, 0.0
It could be maintained at 1 to 0.02%.

In this steady state, the iron-based dross is
Filter 1 at the fine grain stage before it grows to harmful size
It is thought to be adsorbed on. In the case of the conventional technique, the iron concentration in the galvanizing bath is limited to the range of 0.5 to 0.05%, though it depends on the filter replacement cycle.

[0036]

Since the present invention has the above-mentioned structure, it has the following effects. Composed of a ternary intermetallic compound of iron, aluminum, and zinc that forms the dross, the dross is captured and removed by the filtering action and the adsorption action, and the captured dross itself also captures other dross. Since it works as expected, a high dross capturing efficiency can be obtained.

The small dross that is adsorbed and trapped is integrated with the particulates of the filter that is adsorbed as it is or the large dross that is trapped to increase the particle size of the particulates or the large dross of this filter that remains granular. Direction, that is, the direction in which the thickness of the filter in the filtering direction is increased, the small dross that is adsorbed and trapped does not clog the filter, which enables continuous use over a long period of time, and thus the strip is used. It is possible to reduce the production cost and maintenance labor and maintenance cost for filter replacement.

The same material as the dross produced in the zinc plating bath, which is a material composed of a ternary intermetallic compound of iron, aluminum and zinc, can be used as it is, and the dross itself can be used as it is. Therefore, the cost required for manufacturing the filter can be significantly reduced, which can contribute to a reduction in strip production cost.

[Brief description of drawings]

FIG. 1 is a front vertical sectional view showing an embodiment of a filter of the present invention.

FIG. 2 is a front vertical sectional view showing another embodiment of the filter of the present invention.

FIG. 3 is a front sectional view showing a usage example of the filter according to the present invention.

FIG. 4 is a schematic diagram showing a state in which an iron-aluminum-zinc-based compound is bound.

FIG. 5 is an enlarged schematic view of an A portion of the compound shown in FIG.

[Explanation of symbols]

 1; filter 2; granular material 3; container 4; lid 5; hole 6; hole 7; plating bath 8; strip 9; sink roll 10; support roll 11; pump 12; pipe 13; partition wall 14; galvanizing bath 15; Bellmouth

[Procedure amendment]

[Submission date] July 1, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

Claims (3)

[Claims] 1. A filter for removing dross, which is composed of a material composed of a ternary intermetallic compound of iron, aluminum and zinc that constitutes the dross in the zinc plating bath (14). 2. The amorphous bottom dross deposited and precipitated at the bottom of a zinc-based hot-dip bath of an iron-based material, wherein the filter material made of a ternary intermetallic compound of iron, aluminum and zinc. Filter for removing dross. 3. The transmission gap size of the filter (1) is set to 1-5.
The filter for removing dross according to claim 1 or 2, wherein the filter is mm.