JPS62158892A - Manufacture of electrolytic iron - Google Patents

Abstract

PURPOSE:To prevent the surface of electrolytic iron electrodeposited on a cathode from being made uneven when electrolytic iron is manufactured, by using a curved plate having a recessed surface on the anode side as the cathode or putting an anode in a vertical cylindrical body used as the cathode and rotating one of them. CONSTITUTION:A mild steel or pure iron anode and a stainless steel cathode are placed in an electrolytic soln. contg. ferrous ions and electric current is supplied to the electrodes to electrodeposit high purity electrolytic iron on the surface of the cathode. At this time, a recessed cathode 2 is placed in the electrolytic soln. 3 so that the recessed surface is faced toward a flat plate- shaped anode 1 placed in the soln. 3 or an anode 5 is put in a cylindrical cathode 6 whose central axis is in the vertical direction in a noncontact state and the cathode 6 or the anode 5 is rotated. The surface of electrolytic iron electrodeposied on the cathode is made smooth and high purity electrolytic iron without having ruggedness is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing electrolytic iron, and more specifically, it is possible to reduce the unevenness of the electrodeposited surface and electrodeposit thicker iron on the cathode. on how to do so.

Electrolytic iron contains far fewer impurities than ordinary mild steel or pure iron, so it is used in fields that require high quality, such as magnetic materials, electronic materials, alloy materials, and base metal materials for testing and research.

[Conventional technology]

An electrolytic solution is stored in an electrolytic cell, and a rotating drum-shaped cathode with a horizontal rotating shaft is placed in opposition to a plate-shaped mild steel or pure iron anode, and high-purity iron is produced by electrolysis while rotating the cathode. Methods for producing electrolytic iron, which is electrodeposited onto a curved cathode surface, are known. This rotates the cathode in order to degas the gas generated near the cathode surface. An electrolysis method using a flat plate as a cathode is also known, but in that case, means such as forced circulation of the electrolyte solution are employed for degassing.

[Problem that the invention seeks to solve]

When using a rotating drum type or flat plate type cathode as described above, the thickness of the electrodeposited iron cannot be increased because the surface irregularities tend to increase as the thickness of the electrodeposited iron increases. Moreover, as a result, there is a drawback that the number of electrode pull-outs increases.

[Means for solving problems]

As a result of our earnest efforts to solve the above-mentioned problems, the inventors of the present invention have found that if a cathode having a concave curved surface on the anode side is used, the surface irregularities will not increase even if the thickness of the electrodeposited iron increases. The present inventors have discovered that it is possible to obtain thicker electrodeposited iron, and have completed the present invention.

That is, the present invention in its first form is an electrolytic iron method in which an anode and a cathode are placed opposite each other in an electrolytic bath consisting of an aqueous solution containing ferrous ions and a supporting electrolyte as main components, and high-purity iron is electrodeposited on the cathode. The manufacturing method of electrolytic iron is characterized by using a concavely curved curved plate on the anode side as the cathode.

Further, a second form of the present invention is an electrolytic iron method in which an anode and a cathode are placed opposite each other in an electrolytic bath consisting of an aqueous solution containing ferrous ions and a supporting electrolyte as main components, and high-purity iron is electrodeposited on the cathode. A method for producing electrolytic iron, characterized in that a cylindrical cathode is used as the cathode, and an anode that can be inserted into the cylindrical cathode in a non-contact manner is held at the center of the cathode circle to perform electrolysis. It is in. In this second form of the invention, it is preferable that the anode and cathode are held vertically and that the anode and/or cathode are rotated.

[For production]

The reason why the surface irregularities become larger as the thickness of the electrodeposited iron increases in conventional flat or convex cathodes is thought to be as follows. That is, referring to FIG. 3, when crystal grains 2 of electrodeposited iron grow on the surface of the flat plate cathode I, the surface area of the surface formed by the crystal grains 2 is larger than the surface area of the cathode 1 because the surface of the crystal grains is not flat. The current density therefore decreases.

When the current density decreases in this way, the crystal grains 3 that grow next become larger, and the surface area formed thereby also becomes larger. Then, the current density becomes even smaller, and the crystal grains 4 growing thereon become even larger. In this way, as the thickness of the electrodeposited iron increases, the crystal grains become larger, and as a result, the surface irregularities are amplified. Figure 4 shows a case where the cathode is a convex type, but for the same reason as the flat plate cathode in Figure 3, the surface irregularities increase as the amount of electrodeposited iron increases. When iron is electrodeposited on the mold surface, the radius of curvature (r+ = rz ""r3-rs) increases in the thickness direction of the electrodeposited iron, which inherently increases the surface area. As a result, However, as the thickness of the electrodeposited iron increases, the crystal grains tend to become larger, so due to the synergistic effect of these, the irregularities on the surface of the electrodeposited iron increase significantly rapidly. FIG. 4 shows this situation, with crystal grains 12 of electrodeposited iron on the convex cathode 11.
, 13 and 14 are growing sequentially, and the surface irregularities are rapidly expanding.

〔Example〕

FIG. 1 shows an electrolysis device using a cathode having a concave curved surface on the anode side. An anode 1 and a cathode 2 are placed opposite each other, and the anode 1 has a flat plate shape, but the cathode 2 is a curved plate having a concave curved surface on the anode 1 side. The iron material used as the anode may be general mild steel, but pure iron may also be used for the purpose of increasing the purity even slightly.

The cathode is one in which electrolytic iron is electrodeposited by discharge, and a plate-shaped body or a rotating drum made of stainless steel or the like is used as in the conventional method.

Anode l and cathode 2 are immersed in electrolytic bath 3,
The electrolytic bath uses ferrous sulfate and/or ferrous chloride as the main components, and in these sulfuric acid or hydrochloric acid acidic baths, a salt less base than iron with good conductivity is used as a supporting electrolyte. Representative examples include sodium, sodium chloride, potassium sulfate, potassium chloride, magnesium sulfate, magfcium chloride, and calcium chloride.

Electrolysis was actually performed using such an electrolyzer.

The electrolysis conditions are as follows.

Anode: Mild steel plate measuring 840 x 820 x 50 Cathode: The anode side has a concave curved surface of an arc 105 with a radius of 50 mm and a height of 1000 mm. Distance between electrodes of a stainless steel curved plate with a thickness of 5 #: 150 at the center of the cathode Electrolytic bath 2FeC1z 140 g/(I NHaC7!130 g/It pH 4,5~5.0 Bath temperature 90~98℃ Sliding voltage 20. 8~1.2■ Current density: 2.4A/drd Electrolysis was carried out in this way for 96 hours, and high purity iron was electrodeposited to a thickness of 6 squares on the cathode, but the surface of the electrodeposited iron was smooth. When electrolyzing was carried out under the same conditions as above using a plate-shaped body as a cathode, the thickness of the electrolytic iron with a smooth surface was about 3R at most.

FIG. 2 shows an electrolysis device in which the cathode is cylindrical and the anode is arranged within the cathode. In the figure, 5 is an anode, 6 is a cathode, and 7 is an electrolytic bath. The cathode 6 has a hollow cylindrical shape, and inside thereof,
In particular, a rod-shaped anode 5 is arranged at the center. Anode 5 and cathode 6
By arranging them concentrically, the electrolytic conditions on the cathode surface are made uniform. Here, it is preferable to rotate one or both of the anode 5 and the cathode 6 because the electrolytic conditions on the cathode surface become more uniform. Further, it is preferable that the anode 5 and the cathode 6 be arranged vertically in order to make the electrolytic conditions uniform.

Electrolysis was actually performed using such an electrolyzer.

The electrolysis conditions were as follows.

Anode: 5Qmm x 3QQms square mild steel rod cathode; inner diameter IQQum, height 1000mm, thickness 5R stainless steel cylinder, cathode rotation speed: 3r, p, m.

Electrolytic bath: FeCj! , 140 gel NH,CI 130 g/N pH 4,5-5.0 Bath temperature 90-95 Sliding voltage: 1.2-1.8 ■ Current density: 2.4 A/di Thus 96
Electrolysis was carried out for a period of time to electrodeposit pure iron to a thickness of 6 mm on the cathode, but the surface of the electrodeposited iron was smooth.

〔Effect of the invention〕

According to the present invention, by making the anode-side surface of the cathode concave, it is possible to prevent the surface irregularities from expanding when high-purity iron is electrodeposited on the cathode and its thickness increases. As a result, thicker electrodeposited iron with a smoother surface can be obtained, and the number of electrode pull-ups is reduced, improving productivity.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an electrolytic device using a plate-shaped cathode with a concave curved surface on the anode side, Figure 2 is a schematic diagram of an electrolytic device using a cylindrical cathode and a rod-shaped anode inside the cathode, and Figure 3 is a schematic diagram of an electrolytic device using a plate-shaped cathode with a concave curved surface on the anode side. FIG. 4 is a schematic diagram showing the growth of electrodeposited iron on the cathode. FIG. 4 is a schematic diagram showing the growth of electrodeposited iron on the convex cathode. l... Flat cathode, 2.3.4... Crystal grain, 11... Convex cathode, 12, 13.14... Crystal grain, r++rz+rz+ra... Radius of curvature.

Claims (1)

[Claims] 1. A method for producing electrolytic iron in which an anode and a cathode are placed opposite each other in an electrolytic bath consisting of an aqueous solution containing ferrous ions and a supporting electrolyte as main components, and high-purity iron is electrodeposited on the cathode. , a method for producing electrolytic iron characterized by using a concave curved plate on the anode side as a cathode. 2. In an electrolytic iron manufacturing method in which an anode and a cathode are placed opposite each other in an electrolytic bath consisting of an aqueous solution containing ferrous ions and a supporting electrolyte as main components, and high-purity iron is electrodeposited on the cathode, a hollow cylindrical shape is used as the cathode. 1. A method for producing electrolytic iron, which comprises using a cathode and an anode that can be inserted into the cylindrical cathode in a non-contact manner and holding the anode at the center of the cathode to carry out electrolysis. 3. The manufacturing method according to claim 2, wherein electrolytic ironing is carried out by holding the anode and cathode vertically. 4. The manufacturing method according to claim 2 or 3, wherein electrolysis is carried out while rotating the anode and/or cathode.