JPH08120472A - Pickling and descaling of wire rod coil and neutralizing and cleaning of coil after pickling - Google Patents

Abstract

PURPOSE: To provide a pickling method for efficiently peeling scales in the lapped part of wire rods at the time of subjecting a wire rod coil to batch pickling. CONSTITUTION: At the time of subjecting a wire rod coil to pickling, it is executed in such a manner that a pickling bath is stirred and flowed while a fresh pickling soln. is fed even to the closed part of the lapped part of the wire rods. Also, at the time of washing and neutralizing after the pickling, the treatment is executed in such a manner that the soln. is stirred and flowed. Furthermore, by a method in which pickling is executed while a pickling soln. in which the concn. of tervalent iron ions is regulated to 10g/l to 6Og/l. is flowed and stirred, the pickling treatment for a wire rod coil is efficiently made possible. As for the batch pickling method for a wire rod coil, the pickling is finished for a time of about 50% compared to the case of the conventional pickling method, the operability can remarkably be improved, and the wire rods having good surface properties can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims to shorten the time until descaling when the scale formed on the surface of a wire wound into a coil is peeled by pickling and to clean the coil surface after pickling. The present invention relates to a method for descaling by pickling.

[0002]

2. Description of the Related Art A scale is formed on the surface of a wire rod manufactured by hot rolling or a steel wire heat-treated in the secondary processing step, and the scale is formed on the surface prior to wire drawing in the secondary processing of the wire rod. It is necessary to peel off the scale. As a method for exfoliating this scale, there are a mechanical method and a chemical method, or a method in which both are combined. Further, also in the chemical method, there are a strand method in which a wire is made to run in the axial direction to pass through the pickling solution, and a batch method in which the wire is immersed in the pickling solution in a coil form.

In recent years, a mechanical descaling method has also been adopted from the viewpoint of pollution problems and cost reduction, but the pickling method has high productivity and is easily applicable to various steel types. Peeling of scale by pickling is widely adopted because it has advantages such as easy control of lubricity in secondary processing in the post-process by controlling skin. However, when pickling the wire rod coil, the wire rods are bundled in a ring shape and bundled together, so the wire rods overlap and the acid solution does not easily permeate into the coil, and the scale easily remains inside the coil. Therefore, there is a problem that causes trouble in the subsequent process.

As an improvement by means of equipment to solve such a problem, Japanese Patent Laid-Open No. 54-114438 discloses that a wire coil is vibrated during batch pickling of the wire coil and the wire coil is circumferentially mounted on the hook. The method of uniformly pickling the entire length of the wire rod by rotating the wire rod is also disclosed in JP-A-3-6878
No. 9 discloses a method in which an ultrasonic vibrator is installed in a pickling bath and ultrasonic waves are applied during pickling to uniformly pickle the entire wire coil.

However, these conventional techniques have the following problems and are not always sufficient for improving the pickling property of the wire coil overlapping portion. The method of vibrating the coil during pickling requires a large device, which increases equipment costs and makes it difficult to install equipment. Further, there is a problem that the work environment is deteriorated due to the generation of noise, and the vibration is transmitted to the crane or the building of the pickling equipment, which easily causes equipment failure. As described above, the method of giving vibration during pickling has many problems in practical use even though it has an effect of improving scale releasability.

In the method of applying ultrasonic vibration during pickling, the installation position of the ultrasonic vibrator is very important, and when the distance between the ultrasonic vibrator and the wire coil changes, the effect remarkably changes, resulting in scale peeling. The improvement effect of is reduced. Therefore, in order to exert the effect of improving the peelability of the scale, it is necessary to reliably position the wire rod coil, delicate work is required, and the workability is deteriorated. Further, there is a problem that an apparatus for generating ultrasonic waves is expensive and is not easily put into practical use.

On the other hand, as a method for improving the pickling property of an acid solution, JP-A-58-73778 and JP-A-58-78 are known.
Japanese Patent No. 73779 discloses a method of improving the peelability of scale during pickling by controlling the divalent and trivalent iron ion concentrations of a monobasic acid and dibasic acid solution within a certain range. . However, in the method of improving the peelability of scale by pickling solution, it overlaps like a wire coil, and when tightly bound, it is difficult for the acid solution to penetrate into the inside of the wire. It has almost no effect on improving the scale releasability at the same time, and the iron ion concentration increases sharply in the overlapped part and the closed part of the wire, reaching the saturated concentration in a short time, and the dissolution capacity of the scale of the acid solution decreases. However, it cannot be applied to the pickling of the wire coil because it significantly deteriorates the scale releasability of the wire coil.

[0008]

In view of the above situation, the present invention improves the scale releasability at the overlapping portion of the wire coil by using a simple method during the batch pickling treatment of the wire coil, It is intended to provide a method for efficiently and uniformly stripping a wire rod scale over the entire length.

[0009]

In order to improve the scale releasability of the overlapping portion or the closed portion of such wire rods, the present inventors have made a detailed study on the pickling condition, and as a result, achieved the present invention. In the method of performing descaling treatment by immersing the wire coil in a pickling bath, the pickling solution is forcibly stirred and flowed while the wire coil is treated. It is a pickling descaling method.

A method for neutralizing and cleaning a wire coil, characterized in that the solution is treated while being stirred and flowing during the washing or neutralization treatment after pickling.

When stirring the acid solution and the neutralization / cleaning solution, a pipe having a nozzle for spraying a gas is immersed in the pickling bath and the neutralization / cleaning bath, and the nozzle is blown with a gas to blow the acid solution. And a method of pickling and descaling a wire coil, characterized by fluidizing the cleaning solution, wherein the gas sprayed from the nozzle at the time of stirring the pickling solution contains oxygen. Descaling method, neutralization and washing method.

Further, using a pickling solution in which the concentration of trivalent Fe ions in the pickling solution is adjusted to 10 g / l or more and 60 g / l or less, the acid solution is forcibly stirred and fluidized. A method of pickling and descaling a wire coil, which comprises:

As means for stirring and flowing the acid solution or the washing and neutralizing solution in the present invention, for example, a method of installing a screw or the like inside the pickling tank and mechanically stirring,
Any method such as a method of blowing a gas at a constant flow rate into the pickling tank and stirring the acid solution together with the gas flow, or a combination of these methods can be applied.

The degree of fluidization of the acid solution depends on the scale thickness, composition, weight, binding strength of the scale formed on the surface of the wire to be pickled.
It can be appropriately determined depending on the acid concentration of the acid solution, the temperature of the acid solution, etc., and the optimum conditions enable the most efficient pickling.

For example, when a wire rod coil having a good scale releasability is pickled with an acid solution having a high ability to remove the scale, it is possible to sufficiently remove the scale with relatively mild stirring.

On the contrary, when a wire coil having a strong binding strength of the wire coil and a poor pickling and peeling property of the scale is pickled with an acid solution having a low scale peeling ability, the stirring speed of the acid solution is increased. By increasing the kinetic energy, the acid solution can penetrate into the inside of the wire coil,
Peeling of sufficient scale is possible.

On the other hand, if the acid solution is excessively fluidized, the acid solution may be scattered from the pickling tank. Therefore, it is preferable that the acid solution is stirred and fluidized under the minimum necessary conditions. It is also possible to completely prevent the acid solution from scattering by covering the pickling tank with a lid and performing pickling.

In the method of the present invention in which a pipe having a nozzle is immersed in an acid solution, a neutralizing solution and a cleaning solution and gas is blown from the nozzle to stir and fluidize these solutions, the nozzle is provided with simple fine holes. Any one can be used as long as it can blow the gas, such as a nozzle configured to diffuse and discharge the gas.

The gas blowing nozzle may be installed either by preliminarily immersing it in the treatment bath and fixing it, or by immersing it only during the treatment work. To prevent corrosion of the nozzle by the acid solution, Considering the service life, the method of immersing only during working is preferable. Further, when the purpose is only to stir and flow each treatment solution such as an acid solution and water washing,
The type of gas is not particularly limited as long as it does not generate a harmful gas by reacting with the pickling solution, and an inert gas, air or the like can be used.

As a means for controlling the concentration of trivalent iron ions of the present invention, even if a chemical that becomes Fe ³⁺ is added after being dissolved in an acid solution, a gas containing oxygen is blown into the pickling solution. Any method of oxidizing divalent iron ions in the acid solution to form trivalent iron ions can be applied.

When a reagent that becomes Fe ³⁺ is added, the amount of chemicals used is large because the pickling bath is relatively large,
Both Fe ²⁺ and Fe ³⁺ ions are dissolved in the pickling bath and total Fe
Since the ion concentration increases, the saturated solubility of the pickling solution may be reached, and the dissolution capacity of the scale may decrease relatively early. On the other hand, according to the method of the present invention, a gas containing oxygen is blown into the acid solution to oxidize Fe ²⁺ in the pickling bath to produce Fe ^3+.
Is a simple and inexpensive method and is a preferable method.

The type of the blown gas is not particularly limited as long as it is a gas containing oxygen. If the gas has a high oxygen content and the flow rate of the blown gas is large, Fe ²⁺ is supplied in a shorter time.
Can be changed to Fe ^3+, and if the oxygen content is low and the flow rate of blowing is small, it takes a long time to oxidize Fe ²⁺ , but even in this case, iron ions in the acid solution can be sufficiently controlled. . The most convenient and low-cost gas can be factory compressed air or compressed air by a compressor. The method of adjusting the Fe ion concentration in the pickling bath by oxidation of Fe ²⁺ can be controlled by blowing a gas containing air into the acid solution while the pickling treatment is not performed, so that the pickling work is particularly hindered. However, the nozzle for acid solution stirring and fluidization treatment can be used together.

[0023]

[Function] The scale formed on the surface of the wire coil is oxidized during cooling after hot rolling, and the part near the iron of the wire is F
It has a layered structure of eO, Fe ₃ O ₄ , and Fe ₂ O ₃ . In order to improve the peelability of the scale, the scale thickness and the FeO ratio of the scale composition are controlled as physical property values of the scale, and in order to improve the pickling peelability, the scale composition having a high FeO ratio in a thin scale is advantageous. Has been done.
In order to increase this FeO ratio, it is generally necessary to form a secondary scale at high temperature, which results in a thicker scale. Therefore, it was difficult to achieve a thin scale with a high FeO ratio, and it was practically impossible to improve the scale releasability by pickling only with the scale properties.

However, in order to improve the yield of steel materials and improve the pickling workability, there is a demand for thinner wire rods having a scale having a high peeling property. In order to meet this demand, the present inventors have studied in detail a method of pickling and removing the scale of the wire coil.

The pickling and peeling of the scale is carried out by a reaction mainly consisting of monobasic hydrochloric acid, in which the pickling solution enters from scale cracks and defects during the dissolution reaction of FeO, Fe ₃ O ₄ scale and the pickling treatment. The hydrogen ions in the pickling solution from the local battery formed between the base iron, the acid solution, and the scale are gasified into hydrogen gas, and pressure is applied internally from the inside to the scale existing in the upper layer of the base iron. Due to the mechanical peeling action to perform scale peeling.

In the case of sulfuric acid which is a dibasic acid, the scale can be peeled off by almost the same action, but the dissolving ability is not so large as that of hydrochloric acid, and the main factor of scale peeling is the mechanical peeling action by hydrogen gas generation. .

Since the pickling treatment is mainly a chemical reaction as described above, a high concentration and a high temperature are generally directed as a method for improving the peeling ability of the scale. However, when the acid concentration is increased, the basic unit of the pickling solution is increased, the working environment is deteriorated, the life of the iron ion is decreased due to the dissolution of scale, and the life is shortened. It was necessary to take measures for the equipment, such as the scattering of water and having a heating device.

When an acid solution having an enhanced scale peeling ability is used, the wire rod and the acid solution are in contact with each other, and the scale of the portion to which the fresh acid solution is constantly supplied is easily peeled off, and the scale is easily removed in a short time. Although the scale peels off, the scale inside the wire coil is difficult to peel off, so that the scale remains and the difference between the scale peeling portion and the remaining portion increases. Furthermore, when the pickling time is extended to reduce the remaining scale, the erosion of the wire progresses further in the area where the scale is peeled off in the initial stage, causing a problem of quality deterioration due to defects such as pitting corrosion. It was difficult to uniformly peel off the scale over the entire length in a short time.

Particularly, in the simple immersion pickling method, the acid solution stays around the overlapping portion of the wire coil, the iron ion concentration increases in a short time, and a new acid solution is not supplied, so that the divalent acid solution in the acid solution is not supplied. Iron ions are saturated and the scale's dissolution capacity is significantly reduced. For this reason, even if the pickling time is lengthened, the scale remains in a peeled state in the initial stage of pickling, and the effect of improving the peelability of the scale is small. On the contrary, in the scale peeling portion, the scale is peeled off at the initial stage of pickling, and the acid solution and the iron portion are in direct contact with each other, so that pitting corrosion easily occurs, and particularly when the pickling treatment time becomes long, particularly severe pitting corrosion occurs. In order to improve the scale releasability at the overlapping part or the closed part where such unbalanced pickling is performed, it is necessary to enhance the scale removability of the acid solution and complete the treatment in a short time. It is effective to constantly supply the solution.

Vibration pickling is one of the methods for improving the pickling property of the overlapping portion of the wire rods. The present inventors have proposed a simpler and more efficient pickling method as follows: The present invention is an invention of a pickling treatment method in which an acid solution is stirred to give kinetic energy when it is subjected to a descaling treatment by immersing it in. By stirring and fluidizing, the acid solution gains kinetic energy, and it becomes possible to forcibly and continuously supply the acid solution with high scale releasability to the overlapping part boundary of the wire and the closed space. To improve the sex.

When the pickling treatment of the present invention is performed at the same pickling time, the amount of residual scale is reduced to half compared to the conventional method, and conversely, the treatment time is required to obtain the same amount of residual scale. Can be halved. Therefore, according to the method of the present invention, the scale releasability of the overlapped portion and the closed portion of the wire is improved, and the pickling treatment time is shortened,
The difference in scale releasability between the surface, the inside, and the overlapping portion of the wire rod coil is reduced, and uniform scale detachment can be achieved.

When the pickling treatment is performed while stirring and flowing the acid solution, the acid solution is prevented from staying on the surface of the wire even if the pickling time is longer than an appropriate time, and local holes are formed. Since the occurrence of corrosion is suppressed, the surface roughness of the entire wire tends to be small and kept substantially constant. As a result, there is no trouble during wire drawing in the secondary processing in the post process,
A good wire drawing state can be obtained.

Further, even during the washing or neutralization treatment after pickling, the components of the pickling solution adhering to the surface of the wire are forcibly neutralized and washed in a short time by stirring and flowing the treatment liquid. It is possible to significantly reduce the generation of rust caused by acid.

In the method of the present invention in which a pipe having a gas blowing nozzle is immersed in a liquid and the energy of the gas flowing out from the nozzle is used to stir the pickling solution, the neutralizing liquid, and the cleaning liquid, the gas flow rate blown out from the nozzle, the nozzle shape It is possible to freely control the strength of stirring and the direction of liquid flow by adjusting the number of nozzles and the like.

For example, when the binding force of the wire rod coil is weak, the flow velocity of the gas blown from the nozzle does not need to be too high. On the contrary, when the binding strength is strong, the gas blowing speed is increased and a large number of nozzles are arranged to direct it toward the wire rod. The gas is blown out to infiltrate and supply the acid solution, the neutralizing solution, and the cleaning solution even to the overlapping portion of the wire inside the wire coil, thereby enhancing the peelability of the scale.

Next, most of the iron dissolved by the pickling solution due to the influence of iron ions exists in the acid solution as divalent iron ions, but according to the study by the present inventors, trivalent iron ions are present. It was clarified that iron ions improve the peelability of the scale, and the treatment for shorter time is possible. However, according to the conventional pickling method in which the acid solution is not stirred and fluidized, the wire seal portion is filled with and retained by the acid solution containing trivalent iron ions, and is rapidly reduced to divalent iron ions in a short time. Since the iron ion concentration increases, the effect of improving the peelability of the scale disappears. As a result, the concentration of the divalent iron ion approaches the saturation concentration of the acid solution, so the scale releasability deteriorates, and the amount of residual scale on the wire increases.

On the other hand, when an acid solution having trivalent iron ions is agitated and flown to continuously supply a fresh acid solution to the closed portion of the wire coil, an acid solution having improved scale releasability is supplied. Therefore, the scale peeling is completed in a shorter time than in the case where the trivalent iron ion concentration in the pickling bath is not controlled. Therefore, in the present invention, the concentration of trivalent iron ions in the acid solution is specified.

The reason why the stripping time of the scale is shortened by supplying iron ions into the pickling bath is considered as follows. Considering the local cell formation reaction on the surface of the wire scale, the anode and cathode reactions are shown as shown in the following equations. The local battery reaction is shown below. (Anode reaction) Fe → Fe ²⁺ + 2e (Cathode reaction) Fe ₂ O ₃ + 6H ⁺ + 2e → 2Fe ²⁺ + 3H ₂ O Fe ₃ O ₄ + 8H ⁺ + 2e → 3Fe ²⁺ + 4H ₂ O 2H ⁺ + 2e → H ₂

Due to the presence of trivalent iron ions during the exfoliation of the scale due to the formation of the local battery, the following reaction paired with the anodic reaction occurs in the dissolution reaction of base iron, and the trivalent ions are more likely to exist in the acid solution. Reduction to a stable divalent ion takes place, at which time the electrons in the acid solution are consumed. Fe ³⁺ + e → Fe ²⁺

The electrons involved in this reduction reaction are supplied by the dissolution of iron or scale, and the proceeding dissolution reaction of Fe (base iron), which is the other electrode, is promoted as the electrons progress. Fe → Fe ²⁺ + 2e The overall reaction is as follows, and Fe + Fe ³⁺ → 3Fe ²⁺ apparently trivalent iron ions promote the dissolution of iron. It is presumed that since the dissolution reaction is promoted, the presence of trivalent iron ions promotes the local cell reaction and the scale peeling is improved.

However, conversely, when an acid solution having a high Fe ³⁺ concentration is supplied to the space closed by the wire and the acid solution is retained and held, the dissolution of the iron portion of the wire is accelerated and the iron content is rapidly increased. The ion concentration increases and the stripping ability of the acid solution decreases. By such an action, the exfoliation of the scale is promoted by adding trivalent iron ions to the acid solution, but when the Fe ³⁺ concentration is less than 10 g / l, the definite improvement effect of the exfoliation property of the scale is not obtained. It is not recognized, and a trivalent iron ion concentration of at least 10 g / l or more is necessary in order to perform the action of promoting scale peeling. On the other hand, a trivalent iron ion concentration of 60 g / l or more impairs the solubility of the scale,
The Fe ³⁺ concentration in the acid solution was set to 60 g / l or less because local dissolution of the base iron is promoted and pitting-like defects are increased.

However, the iron ions produced by the descaling reaction are divalent iron ions of Fe ²⁺ , and the divalent iron ions are inevitably produced in the pickling bath by continuing pickling. In order to achieve the object of the present invention, it is necessary to take measures to externally control the trivalent iron ion in order not to naturally become trivalent iron ion. However, when controlling the iron ion concentration by adding chemicals, the controllability is high, but the running cost is high and the total iron ion concentration increases, so the saturated concentration of the acid solution is reached relatively quickly and Dissolution capacity is reduced.

On the other hand, the method of oxidizing Fe ²⁺ ions present in the acid solution of the present invention by blowing a gas containing oxygen into the acid solution to form Fe ^{3+ is} as follows. The oxidation ratio of Fe ²⁺ is determined by the amount and time. By properly selecting this condition, the Fe ³⁺ concentration can be controlled and the total iron ion concentration in the acid solution can be kept constant to prevent a decrease in the dissolving ability of the acid solution,
This is a more preferable method since the life of the pickling solution can be maintained for a long time.

[0044]

【Example】

(Example 1) A pickling treatment was performed using a wire rod coil formed by binding 1 ton of 5.5φ wire rod of SWRH82A. The scale property of this wire rod is 10.3 μm in thickness, and the composition is obtained from the intensity peak ratio by X-ray diffraction after peeling off the scale.
64.4%, Fe ₃ O ₄ 34.2%, Fe ₂ O ₃ 1.4
%, And FeO, Fe ₃ O ₄ , and Fe ₂ O ₃ are formed in layers from the base iron side. The pickling bath has a hydrochloric acid concentration of 2
0%, temperature 20 ° C, Fe ²⁺ concentration 22g / l, Fe ³⁺
A concentration of 4.3 g / l was used. With this pickling solution, the peeling time of the scale where the cut sample did not overlap was 3 minutes.

As a method of stirring and fluidizing the acid solution according to the method of the present invention, a tubular ENVI pipe having nozzles with a diameter of 1.2 mm at a pitch of 50 mm is immersed in the bottom of the pickling tank, and gas is discharged from the nozzle. It was done by blowing out. The wire rod coil is hung by a hook, moved by a crane and immersed in a pickling tank, and then compressed air of 1 Nm ³ / with a pressure of 4 kgf / cm ^2.
The amount of residual scale of the wire rod coil was measured by changing the treatment time by flowing min and stirring and flowing the acid solution in the acid bath.

As a comparative example, the residual scale amount of the conventional method when air was not blown was also measured for each similar treatment time.
The amount of residual scale was measured after pickling, followed by washing with a washing tank and drying. In the case of the present invention, air was blown into the washing treatment tank at this time as well, and the treatment was performed by stirring and flowing water. To measure the residual scale amount, after removing the binding of the wire rod coil, cut two rings at 100-ring intervals in succession into 1 ring and divide it into 8 equal parts, and weigh it to W1. For this purpose, it is immersed in a hydrochloric acid solution to which an inhibitor has been added, dried and then weighed again as W2, and the residual scale (% by weight) = (W1−W2) / W1 × 10
The residual scale amount was obtained by the calculation formula of 0. At this time, although the inhibitor was added when the scale was completely peeled off, the ground iron dissolved and the weight loss increased, so a wire rod cut to the same length as the sample with no scale attached was used as a dummy. After washing, this weight change was corrected as the dissolved weight of base iron.

The results are shown in FIG. When compared with the same pickling time, the method of the present invention in which air is blown during pickling has been reduced to about half the residual scale amount of the wire rod pickled by the conventional method, and the residual scale amount equivalent to that of the conventional method. In that case, the pickling time was reduced to about half.

Further, as shown in FIG. 2, the surface roughness of the wire after pickling is smaller than that of the conventional method by pickling by the method according to the present invention, and it is large even if the pickling time is long. There is no deterioration in surface roughness.

Furthermore, the wire rod from which the scale has been peeled off according to the method of the present invention has less rust even when stored in an atmospheric environment as compared with the wire rod coil pickled by the conventional method, and is sufficiently washed with water to remove the acid. It was found that the removal effect of the solution was also sufficient.

(Example 2) Under the same conditions as in Example 1, the pickling treatment of the wire coil was performed by changing the iron ion concentration of Fe ^{3+ in} the pickling solution. For the acid solution, before the pickling, chemicals are added to dissolve Fe ³⁺ and air is blown in to remove Fe ²⁺ from Fe ^3+.
Stir and fluidize the acid solution with the acid solution oxidized to
The wire rod coil was pickled for 10 minutes for pickling, and the amount of residual scale was measured.

FIG. 3 shows changes in the blowing time and the concentrations of Fe ²⁺ and Fe ³⁺ when air is blown into the acid solution in which initial Fe ²⁺ is about 60 g / l. By blowing air for a long time, Fe ²⁺ is oxidized to Fe ³⁺ , and almost all Fe ^{2+ is}
It can be seen that is oxidized to Fe ³⁺ . Further, the total iron ion concentration has a substantially constant value, and the iron ion concentration does not increase.

FIG. 4 shows the relationship between the residual scale amount and the iron ion concentration of Fe ^{3+ in} the acid solution when the method of the present invention and conventional simple immersion pickling are used. From this rather the effect of improving the residual amount of scale due to the Fe ³⁺ added Fe ³⁺ until 25 g / l in the conventional pickling process according to simple immersion, Fe ³⁺ is 25 g / l
Above, the amount of residual scale increased and the peelability of the scale deteriorated. On the other hand, in the method of the present invention, the amount of residual scale decreases when the amount of Fe ³⁺ is 10 g / l or more, and the amount of residual scale further decreases as the amount of Fe ³⁺ increases. But 6
At 0 g / l or more, the effect of improving scale releasability was not recognized, and the effect of improvement was small. Also, no clear difference in the residual amount of scale reduction effect by the control of the Fe ³⁺ by oxidation in the case of chemicals added and Fe ^2+, apparently residual amount of scale compared to the case you did not control the Fe ³⁺ together A reduction effect was recognized. However, when the Fe ³⁺ concentration was 60 g / l or more, pitting-like defects frequently occurred on the surface of the wire and the surface quality deteriorated.

Since Fe ³⁺ in the acid solution is reduced during the pickling process and becomes Fe ²⁺ , it is always appropriate to blow air again after the pickling to reduce Fe ²⁺ to Fe ^3+. Fe in the range
It can be adjusted to ³⁺ , which is advantageous in terms of cost and allows easy control of iron ions.

[0054]

EFFECTS OF THE INVENTION In the immersion pickling of the wire coil, the pickling solution in the pickling tank according to the method of the present invention is agitated and allowed to flow, whereby a fresh acid solution is continuously applied to the overlapping portion or the closed portion of the wire coil. It can be supplied, and the residual scale at the overlapped portion or the closed portion of the wire rod coil can be halved, so that the pickling time can be reduced to half. Further, the acid solution can be agitated and fluidized by a simple device in which gas is blown into the acid solution from a nozzle. By controlling the concentration of trivalent iron ions in the pickling bath, scale releasability of the pickling solution can be further improved, and efficient pickling can be achieved by using the pickling method in which the pickling bath is stirred and fluidized. Is possible. The present invention can be easily carried out with a pipe and a nozzle capable of blowing gas and compressed air, and by using a gas containing oxygen as the blowing gas, it can be easily carried out by oxidation of divalent iron ions. This is an industrially very useful invention because it is possible to control the concentration of valent iron ions and a great effect can be obtained with a simple device.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the pickling time and the residual scale amount of the present invention and a conventional pickling method.

FIG. 2 is a diagram showing changes in surface roughness of a wire according to the method of the present invention and a conventional pickling method.

FIG. 3 is a diagram showing changes in iron ion concentration when oxygen is blown into an acid solution.

FIG. 4 is a diagram showing a relationship between Fe ion concentration and residual scale amount.

Claims (6)

[Claims] 1. A method of pickling and descaling a wire coil, which comprises performing a descaling treatment by immersing the wire coil in a pickling bath while forcibly stirring and flowing the pickling solution. 2. A method for neutralizing and cleaning a wire coil, which comprises treating the solution while forcibly stirring and flowing the solution at the time of water washing or neutralization after pickling. 3. A pickling descaler for a wire rod coil, characterized in that a pipe having a nozzle for blowing gas is immersed in a pickling bath, and the gas is blown toward the wire rod coil to fluidize the acid solution. Method. 4. A pipe having a nozzle for blowing gas is immersed in a washing and neutralizing treatment liquid, and the gas is blown toward the wire coil so that the washing and neutralizing solution is fluidized. How to neutralize and clean the wire coil. 5. The pickling and descaling method for a wire rod coil according to claim 3, wherein the gas sprayed from the nozzle contains oxygen. 6. The pickling solution in which the concentration of trivalent Fe ions in the pickling solution is adjusted to a concentration range of 10 g / l or more and 60 g / l or less is used. Method for pickling and descaling of wire coil of.