JPH0356315B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing electrolytic iron, in particular an electrolytic method in which iron is used as an anode in an electrolytic solution, and high-purity iron is electrodeposited under high current density on a cathode rotating around a rotating shaft. It relates to a method of manufacturing iron. 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. [Prior art] An electrolytic solution is stored in an electrolytic cell, and during electrolysis, a rotating drum-type cathode with a horizontal rotating shaft and a flat plate-shaped mild steel or pure iron anode are placed opposite each other, and electrolysis is carried out while rotating the cathode. A method for producing electrolytic iron in which high-purity iron is electrodeposited on a curved cathode surface is known. This rotates the cathode for degassing to prevent gas generated near the cathode surface from being mixed into the electrolytic iron. An electrolytic method using a plate as a cathode is also known, but in that case, means such as intensive circulation of the electrolytic solution are adopted for the purpose of degassing mentioned above. [Problems to be Solved by the Invention] In the case of the above-mentioned rotating drum system, the anode is made of a flat plate and is suspended above the surface of the electrolyte. There is a problem in that the distance between the electrodes or the angle they form with each other is not constant depending on the position of the electrode surface. Therefore, the conditions for electrodeposition differ depending on the position of the cathode surface, especially on the sides, top, and bottom of the cathode drum (although the cathode is rotating, so it is eventually averaged out), and the cathode surface is not used effectively, and the current density distribution is non-uniform. Furthermore, this arrangement of the two poles has the disadvantage that the apparent critical current density is also small. In addition, with recent technological innovations, ultra-high purity and ultra-low content of specific elements are desired in special fields, and non-metallic elements other than metallic elements, which traditionally depended on the selection of anodes, have become desirable. For example, the content of elements such as carbon (C), sulfur (S), chlorine (Cl), oxygen (O), nitrogen (N), and hydrogen (H) has also become a problem. The source of the mixture of these elements is the electrolyte component or slime, and it is thought that the electrolyte or slime is adsorbed and drawn into the recesses created when the hydrogen gas generated near the cathode is desorbed. [Means for Solving the Problems] As a result of intensive research to solve the problems of the prior art, the present inventors have developed a method in which the cathode is made into a rotating drum type having a vertical rotation axis, and the anode is surrounded by the cathode drum. We succeeded in solving the above problem by arranging the cathode in a cylindrical shape so that it is almost parallel to the surface and performing electrolysis while rotating the cathode. In the conventional system using a rotating drum cathode with a horizontal rotation axis, the configuration in which a cylindrical anode with a constant distance between the electrodes is attached to the curved surface of the cathode complicates the equipment, and in that case, electrodeposition is difficult. The operation of pulling up the anode to take out the electrolyzed iron also becomes complicated. Furthermore, in a configuration in which a cylinder is vertically divided in half and an anode is placed below the cathode drum, the cathode surface that is not surrounded by the anode remains, which does not solve problems such as uneven distance between the electrodes and complicates the device. There are problems such as: On the other hand, if a rotating drum type cathode having a vertical rotation axis is used, it is easy to arrange a cylindrical anode around the cathode substantially parallel to the curved surface of the cathode. The anode may have a cylindrical shape or a polygonal shape close to the cylindrical shape, or a plurality of strip-shaped anodes may be arranged in a cylindrical shape. In this way, by creating a structure in which the cathode surface and the anode surface are opposed to each other in parallel, the electrodeposition conditions on the entire surface of the cathode are uniform, the entire surface of the cathode is effectively utilized, and the anode and wear are completely eliminated. is uniformed. Furthermore, the current density distribution is made uniform and the critical current density is increased (productivity per hour is improved). Furthermore, when electrolyzing with such an electrode arrangement, impurities in the electrolytic iron, especially gas components such as Cl, O,
The effect of reducing the content of elements such as N and H was observed. Moreover, this effect of reducing impurities is due to the uniform current density distribution, which suppresses hydrogen gas generation. In addition, since the cathode drum rotating shaft is vertical, stirring of the electrolyte is reduced, oxidation by air is prevented, and the electrolyte is kept clean. [Example] FIG. 1 shows an electrolytic apparatus according to an example of the present invention. An anode 3 and a cathode 4 are placed opposite each other in an electrolytic solution (electrolytic bath) 2 contained in an electrolytic bath 1 . The cathode 4 is typically made of stainless steel and has a rotating drum shape with a vertical rotation axis. The cathode drum 4 is suspended from above and can be pulled up together with the support 5 above the liquid surface. In this support part 5, referring to the plan view of FIG. 2, the rotation of the drum 4 is
A drive roller 7 connects a wheel 6 to a drive roller 7 connected via a rotating shaft.
If the driving roller 7 is configured to be able to approach or move away from the car 6 using a hydraulic or pneumatic cylinder 8, the work of pulling up the cathode drum is facilitated. The cathode 3 is made of relatively pure iron material such as soft iron or pure iron. Although the shape of the anode 3 may be cylindrical or polygonal, it is economical and convenient to arrange a plurality of strips around the cathode drum 4 in a cylindrical shape. Anode 3 is also suspended from above,
It can be lifted above the liquid level. Power is supplied to the anode 3 and current is collected from the cathode 4 in the electrolytic bath 2 through members 9 and 10. The power supply member 9 and the current collection member 10 are made of titanium, for example. In such an electrolytic apparatus, electrolysis was actually carried out under the following conditions to electrodeposit electrolytic iron on the curved surface of the cathode. Cathode: diameter 1.3 m, length 1.2 m, anode: 54 strips made of mild steel, 8 cm x 1 m, 8 cm thick, arranged in a cylindrical shape around the cathode. Distance between electrodes: 15 cm. Electrolytic bath: FeCl ₂ 1.0 mol/NH ₄ Cl 2.0 mol/bath HCl PH 4.8-5.1 Bath temperature 9.5℃ Voltage: 1.3V Cathode rotation speed: 4 rpm (peripheral speed 0.27 m/s) Current density: 3.4 A/dm Electrolysis was performed for 120 hours under the conditions of ² or more. However, the anode wear was very uniform across the anode. The content of each element of Cl, O, N, and H in the electrolytic iron thus obtained was measured. The results are shown in Table 1 below. Also, the limiting current density in the above electrolytic cell is
It was 20A/ ^dm2 . For comparison, a rotating drum-type cathode having a horizontal rotating shaft and a plate-shaped anode were placed opposite each other in an electrolytic bath, and electrolysis was carried out while rotating the cathode to electrodeposit electrolytic iron on the curved surface of the cathode. The electrolysis conditions were as follows. Cathode: Stainless steel, diameter 1m, length 1.8m Anode: Mild steel, 15cm x 1m, 15cm thick plate 2
The plate is suspended vertically parallel to the axis of rotation of the cathode. Distance between electrodes: 15 cm at the shortest point. Electrolytic bath: 1.0 mol of FeCl ₂ / 2.2 mol of NH ₄ Cl / bath HCl PH 5.2 Bath temperature 90°C Voltage: 3.8 V Cathode rotation speed : 4 rpm (peripheral speed 0.21 m/s) Current density: 3.4 A/dm ² Electrolysis was performed for 120 hours under the following conditions. The anode was depleted more in the center of the anode near the side of the cathode drum, and less depleted further away from it. In addition, Cl, O,
The content of each element, N and H, was measured. The results are shown in Table 1 below. The limiting current density in this electrolytic cell was 10 A/dm ² .

〔Effect of the invention〕

According to the present invention, in the method for manufacturing electrolytic iron using a rotating drum type cathode, the cathode surface and the anode surface are arranged substantially parallel to each other over their entire surfaces, so that the cathode surface can be used effectively, and the cathode surface The electrodeposition conditions and electrode wear on the anode surface become uniform, and the limiting current density increases. Furthermore, according to the method of the present invention, the content of elements such as Cl, O, N, and H in the electrolytic iron electrodeposited on the cathode surface is reduced. These elements are gas components, and it is thought that the change in the rotation axis of the cathode rotating drum from horizontal to vertical facilitated the removal of gas components generated near the cathode surface.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an electrolytic device according to an embodiment of the present invention;
FIG. 2 is a plan view of the cathode drum support drive section of the electrolyzer shown in FIG. 1. 1... Electrolytic cell, 2... Electrolytic bath, 3... Anode, 4
...Cathode (rotating drum), 5...Support part, 6...
Car, 7... Drive roller, 8... Cylinder, 9...
Power feeding member, 10... Current collecting member.

Claims (1)

[Scope of Claims] 1. Production of electrolytic iron in which high-purity iron is obtained on the curved surface of the cathode by electrolyzing a rotating drum-shaped cathode and an anode made of mild steel, pure iron, etc. in an electrolytic solution housed in an electrolytic cell in opposition to each other. A method for producing electrolytic iron, characterized in that a rotating drum-type cathode has a vertical rotation axis, an anode surrounds the cathode and is arranged approximately parallel to the curved surface of the cathode, and electrolysis is carried out while rotating the cathode. . 2. The method according to claim 1, wherein the anode is cylindrical. 3. The method according to claim 1, wherein the anode is polygonal. 4. The method according to claim 1, wherein the anode consists of a plurality of strips and is arranged in a cylindrical shape around the cathode.