JPH0353394B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing electrolytic iron using an acidic hydrochloric acid bath containing ferrous chloride, sodium chloride, and/or potassium chloride as an electrolytic bath. Electrolytic iron contains far fewer impurities than ordinary mild steel, 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. However, with recent technological innovations, ultra-high purity and ultra-low content of specific elements are desired in special fields. Ammonium sulfate or ammonium chloride has PH buffering properties, high conductivity, stabilizing properties that prevent bath change due to oxidation of ferrous ions to ferric ions, and uniformity of the structure of the inner and outer layers of electrolytic iron. Currently, it has been exclusively used for this purpose. However, when these bath components are used, as shown in Table 1, even if pure iron is used as the anode, the content of each component element does not decrease much compared to the case of general mild steel, but is relatively high. This is unsatisfactory for fields that require reductions in elements, and technical improvements have been desired.

[Table] Each element is analyzed using the following method. (The same applies hereafter) C: Combustion - Infrared absorption method S: Same as above P: Molybdenum blue spectrophotometry Si: Same as above Mn: Atomic absorption spectrophotometry Cu: Same as above N: Distillation - Indophenol spectrophotometry here Pure iron is obtained by electrolyzing general-purpose mild steel once using a conventional method or refining it using a dry method. As a result of intensive research into reducing the content of each element, the present inventors found that by adding sodium chloride and/or potassium chloride as a supporting electrolyte to an acidic hydrochloric acid bath containing ferrous chloride, the content of each element can be reduced significantly compared to conventional methods. We succeeded in obtaining electrolytic iron with excellent low impurity content and completed the present invention. That is, the gist of the present invention is a method for producing electrolytic iron in which an iron material is used as an anode and ferrous chloride is the main component of the electrolytic bath, and in which sodium chloride and/or potassium chloride is added to a hydrochloric acid acidic electrolytic bath. It is in. Hereinafter, the content of the present invention will be explained in more detail. The iron material used as the anode may be general mild steel, but pure iron may be used for the purpose of increasing the purity even a little.
The cathode is one on which electrolytic iron is electrodeposited by discharge, and a plate-shaped body made of stainless steel or the like or a rotating drum is used as in the conventional method. The electrolytic bath is an acidic hydrochloric acid bath containing ferrous chloride, sodium chloride, and/or potassium chloride as main components, and the concentration of ferrous chloride is 0.5 to 0.
1.5 mol/preferably 0.8 to 1.2 mol/, and sodium chloride and/or potassium chloride is adjusted and maintained at 2 to 4 mol/preferably 3 to 3.5 mol/. If these components are outside the above range, the bath stability may decrease, the electrical conductivity may deteriorate, or
This is undesirable because it lowers the yield of homogeneous electrolytic iron. The pH of the bath is acidic because it is a hydrochloric acid bath, but 3.5 to 4.5 and preferably 3.8 to 4.2 is desirable in terms of bath stability (stability of Fe ²⁺ ) and homogeneity of the product electrolyzed iron. To be elected. The bath temperature is selected to be 65 to 90°C, preferably 70 to 80°C, for the same reason as in the case of pH. The present invention will be explained below with reference to Examples. Example 1 General purpose mild steel and pure iron were used as the anode, and a stainless steel rotating drum was used as the cathode. The electrolytic bath conditions were as follows: FeCl ₂ 0.9 to 1.0 mol/(hydrochloric acid bath) NaCl 3 mol/(hydrochloric acid bath) PH 4.1 to 4.2 Bath temperature 70 to 75°C Voltage 3.5 V Current density 2.5 A/dm ² . The impurities contained in the electrolytic iron obtained as a result of electrolysis were analyzed and are listed for each element in Table 2.

[Table] Example 2 The same conditions as in Example 1 were used except that KCl was used instead of NaCl. The results are shown in Table 3.

[Table] Example 3 In Example 1, 1/2 of the number of moles of NaCl was
The same conditions were used except that KCl was substituted. The results are shown in Table 4.

[Table] As is clear from the results of the above examples, it was found that the impurity content could be extremely reduced by using the electrolytic bath of the present invention.

Claims (1)

[Scope of Claims] 1. A method for producing electrolytic iron using iron material as an anode and ferrous chloride as the main component of the electrolytic bath, characterized in that sodium chloride and/or potassium chloride is added to the hydrochloric acid acidic electrolytic bath. Method of manufacturing iron. 2 Claim 1 in which the pH of the electrolytic bath is maintained at 3.5 to 4.5 using hydrochloric acid and caustic soda
The method for manufacturing electrolytic iron described in Section 1. 3. The method for producing electrolytic iron according to claim 1 or 2, which is carried out while maintaining the temperature of the electrolytic bath at 65 to 95°C.