JPS5839234B2 - Pickling and descaling method for steel wire rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for descaling steel wire rods by pickling.

Conventionally, a hydrochloric acid solution has been used in a steel wire descaling operation using a monobasic pickling solution.

The general pickling conditions are: (1) Hydrochloric acid concentration 10-20wtφ (2) Solution temperature Room temperature to 40℃ (3) Immersion time 20-40m1n (*However, when the steel wire is wound into a coil and immersed.

).

That is, in conventional pickling descaling, the only substance involved in descaling is acid, and in order to promote the descaling action, a method of changing the physical environment, that is, a method of changing the solution temperature, was adopted. It is.

However, if the solution temperature is too high, fumes etc. will be scattered, and the equipment will inevitably need to be enlarged, leading to an increase in the cost of descaling.

In view of the above-mentioned circumstances, the present invention was made for the purpose of shortening the descaling time without making a large capital investment. Add 0.2w of FeCt2 to the saturation concentration.
Add t% to saturation concentration and FeCt3 to 1wt% to saturation concentration, perform pickling descaling operation in the solution, measure the redox potential of Fe3+/Fe2+ during this operation,
The point is that Fe3+ is adjusted so that it always exists in the pickling solution in an amount of 1 wt% or more.

Examples will be described in detail below based on drawings and tables showing examples.

FIG. 1 shows one embodiment of the present invention, in which 1 is a pickling liquid tank, 2 is a steel wire rod fed in the direction of the arrow under constant tension at a predetermined speed, 3 is a guide roll, and 4 is a pickling liquid tank. The pickling solution contains 1 Owt% HCt and 10 wt% F
FeC4 is included in eCt2 and lwt.

Reference numeral 5 indicates a platinum electrode for measuring the redox potential of Fe3+/Fe2+ in the pickling solution 4, and reference numeral 6 indicates a mercurous chloride electrode.Both electrodes 5 and 6 are each connected to the potential detector 1, and the potential detector At 7, the potential difference between the electrodes 5 and 6 is measured.

8 is FeC that stores and manages high concentration FeCL and aqueous solution 9.
t3 tank, 10 indicates an injection pipe that leads the FeCt3 aqueous solution 9 to the pickling liquid tank 1, a valve 11 is provided in the middle of the injection pipe 10, and the valve 11 is operated by the electric energy emitted by the potential difference detector 7. It is configured to open and close depending on the predetermined case.

Specifically, the potential difference detected by both electrodes 5 and 6 is "
The concentration of salt containing Fe3+ (FeCl2) is less than 1 wt%.

”, the valve 11 automatically opens and the highly concentrated FeCl3 aqueous solution 9 flows from the pouring pipe 10 into the pickling liquid tank 1.
It is configured to be injected into the

The opening/closing time of the valve 11 is determined by conditions such as the capacity of the pickling liquid tank 1, the wire diameter and quality of the steel wire used.

Tables 1 and 2 below show the results of descaling using the method of the present invention and the results of descaling using the conventional pickling solution (10 wt% H
This is shown in comparison with the results obtained by CZ).

That is, in the above embodiment, as shown in FIG.
The steel wire rod 2 is well descaled in the presence of Fe2+ and Fe''.

In this 5, the pickling mechanism of the present invention is as follows: HCt corrodes the base iron through the cracks in the scale, and H2 generated in the above reaction applies internal pressure to the Fe504 layer and Fe2O3 layer that form the upper layer of the scale. This allows scale to be removed efficiently.

In this case, Fe contained in the pickling solution 4 in the example
3+ reacts as shown below and contributes to improved descaling performance (shortened pickling time).

Tables 1 and 2 above clearly show this improvement in descaling performance. Compared to the conventional example, the speed in Table I is about 2.5 times faster, and the speed in Table II is about 2.5 times faster than in the conventional example. Good descaling conditions were obtained at twice the speed.

By the way, Fe2+ in FeCl2 generally increases the amount of corrosion when the amount added is 15 wt% or more.
In the case of the present invention, Fe"JurikiS coexists, and FeCl2
Even if the amount is 0.2 wt%, a good descaling state can be obtained.

On the other hand, the amount of F♂ decreases little by little during the descaling operation.

That is, Fe3+ is reduced to Fe2+ by HC and eJ.

However, in the above example, FeCl3 in the pickling solution 4
When the amount of FeCl3 is less than 1wt%, the electric energy emitted from the potential difference detector 7 opens the valve 11, and a high concentration FeCl3 aqueous solution 9 is poured into the pickling solution 4 from the injection tube 10 to check the Fe3+ content. By properly holding and adjusting it, descaling operations can be performed continuously and successfully.

In addition, in the present invention, the amount of FeCl3 added is always 1w.
The reason for setting it above t% is as shown in the graph of Figure 2.
This is because the effect of adding FeC73 appears at a concentration of 1wt%II or more.

The graph shows 10 wt% H as the base of pickling solution 4.
CA+10wt%FeCt2 is used, the pickling solution temperature is 15℃, the steel wire used is 0.5% carbon steel, and the display is Table-1
, is the same as Table-2.

As explained above, the present invention significantly shortens the time required for descaling compared to the conventional pickling descaling method. The amount of Fe3+ in the pickling solution is maintained and adjusted by measuring the redox potential, so no special equipment is required, and the time required for descaling is shortened without raising the solution temperature. Therefore, the problems such as fume scattering described at the beginning cannot be eliminated, and the amount of Fe3+ is always maintained at an appropriate level in the pickling solution, so that a good pickling and descaling operation can be carried out smoothly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG. 2 is a schematic diagram showing an embodiment of the present invention.
It is a graph displaying the effect of addition of Cl3.

Claims (1)

[Claims] In a pickling and descaling method for descaling a steel wire with a pickling solution containing 1wtφ to saturation concentration of a 11-base acid, FeCJ! . 0.2 wt% ~ saturation concentration and FeCt3 ~ 1 wt%
Fe in the pickling solution during descaling operation by adding saturating concentration.
A method for pickling and descaling steel wire rods, the method comprising: measuring the redox potential of each of Fe3+ and Fe2+, and adjusting the Fe3+ so that it always exists at 1 wt% or more in the pickling solution.