JPS62161986A - Manufacture of electrolytic iron - Google Patents

Abstract

PURPOSE:To flocculate and precipitate floating substance such as slime in an electrolyte bath to clean it and to manufacture a high quality electrolytic iron, by adding polyacrylamide and sodium acrylate flocculant into the electrolyte bath at manufacturing electrolytic iron. CONSTITUTION:The electrolyte bath 2 contg. ferrous ion is fed into the electrolytic cell 1, a rotary drum cathode 4 made of stainless steel and anodes made of soft steel or pure iron surrounding it are arranged and the bath is electrolyzed to electrodeposit iron on the cathode 4. Noble metal components having smaller ionization tendency than Fe and fine slimes of insoluble, soln. resistant substances float and exist in the bath 2, these are entangled into electrodeposited iron and quality thereof is deteriorated. For preventing this, a part of the bath 2 is continuously taken out, fed in a treating vessel 5, a polyacrylamide and sodium acrylate flocculant 6 is added to flocculate, precipitate and separate slime, the bath 2 is cleaned and returned to the vessel 1. Flocculant can also be added to electrolyte bath in electrolytic cell directly. High quality electrolytic iron free from entangling of slime is obtd. on the cathode 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing electrolytic iron. More specifically, the present invention relates to a method for producing electrolytic iron, and more specifically, the purity of electrodeposited iron is improved by precipitating and removing suspended matter in an electrolytic bath using a flocculant. Regarding how to improve.

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 metal materials for testing and research.

[Conventional technology]

In the electrolytic refining method of iron, raw iron such as mild steel or pure iron is used as an anode, and an aqueous solution of an appropriate iron salt is used as an electrolyte to obtain extremely pure iron on a cathode such as stainless steel. Among the crude metals, those having a smaller ionization tendency than the target metal and insoluble or poorly soluble substances remain undissolved and adhere to the anode, or become precipitates and remain at the bottom of the tank. Metals whose ionization tendency is greater than that of the target metal are dissolved from the anode, but remain in the solution without being deposited at the cathode. Only the target metal is dissolved from the anode and precipitated on the cathode, and the impurities end up adhering to the anode, settling at the bottom of the tank, or remaining in the liquid and not reaching the cathode.

[Problem that the invention seeks to solve]

Among the crude metals, culprit components that have a smaller ionization tendency than the target metal, as well as insoluble, soluble, or poorly soluble substances, remain undissolved and adhere to the anode or accumulate as slime on the bottom of the tank. Base components with a large tendency to ionize are dissolved from the anode but do not reach the electrodeposition potential, so they accumulate in the solution in the form of ions. In the end, only the target metal will be electrodeposited among the materials melted from the anode. Therefore, in theory, 100% of the target metal should be obtained.

However, in reality, components with a low ionization tendency or insoluble substances are engulfed in the electrodeposited iron as floating slime, making it difficult to obtain pure iron.

The causes of slime include metals more harmful than iron (floating anode residue) caused by impurities in the anode, which is the iron raw material, as well as ferrous ions in the electrolytic bath that are oxidized by air and become ferric ions. This forms slime as hydroxide. These slimes float in the electrolyte and reach the cathode, where they become entangled in the electrodeposited iron. Such slime and other suspended matter in the bath adversely affect the impurity content of the electrodeposited iron.

[Means and effects for solving the problems] As a result of intensive research and efforts by the present inventors to solve the problems of the above-mentioned prior art, floating substances such as slime in the electrolyte solution are removed from polyacrylamide-acrylic The present invention was completed based on the discovery that WE can be collected and removed using an acid-soda flocculant, thereby reducing the impurity concentration in electrolytic iron.

That is, the present invention provides a method for producing electrolytic iron in which a cathode for iron electrodeposition and an anode made of iron for refining are placed opposite each other, and high-purity electrolytic iron is electrodeposited on the cathode using an electrolytic solution containing a supporting electrolyte.
A polyacrylamide-sodium acrylate flocculant is added to the coagulation and sedimentation treatment tank in the electrolyte circulation system provided inside the electrolytic cell containing the cathode and anode and/or outside the electrolytic cell, to remove suspended matter in the electrolyte. There is a method for producing electrolytic iron characterized by precipitating and removing.

The polyacrylamide-sodium acrylate flocculant is based on polyacrylamide and is a partially hydrolyzed product thereof. When expressed as a general formula, however, 0. It has a molecular structure expressed by x<1. Acrylamide is nonionic, while sodium acrylate is anionic. Therefore, it is thought that the nonionic part and anionic part exist in close proximity on the same molecule, effectively neutralizing floating matter in the bath that has a complex charge state, and colliding with each other to cause the particles to grow larger and aggregate. It will be done.

Although there are various types of floating substances in the bath, anionic flocculants are particularly effective, and preferably produce -COONa groups (anionic groups) of 3 to 8 mag.% and 15 to 25 mag.%, respectively. Effective results have been obtained by continuously adding a polyacrylamide-sodium acrylate mixture in a weight ratio of 2:3 to 2:5 at a concentration of 1 ppm to the electrolyte.

The flocculant may be added to the electrolytic bath, or may be added to a purification tank in the electrolyte circulation system provided outside the electrolytic bath.

The amount of addition is approximately 1 to 5 ppm continuously.

〔Example〕

This will be explained with reference to the drawings.

In FIG. 1, an anode 3 and a cathode 4 are placed opposite each other in an electrolytic solution 2 contained in an electrolytic cell 1. In this example, the cathode 4 is in the form of a rotating drum and has a horizontal rotation axis, and the anode 3 is a plate-shaped body arranged parallel to the rotation axis of the cathode 4. However, the anode and cathode may be plate-shaped bodies arranged in parallel, or may have other configurations. 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 made of electrolytic iron that is electrodeposited by discharge, and stainless steel is preferably used because of its cost and ease of handling.

A part of the electrolytic solution 2 in the electrolytic cell 1 is sent to the coagulation-sedimentation treatment tank 5.
After being treated with a polyacrylamide-sodium acrylate flocculant in the purification treatment tower 5, it is returned to the electrolytic cell 1. In the coagulation-sedimentation treatment tank 5, a polyacrylamide-sodium acrylate-based flocculant is continuously added to the electrolytic solution 2 at a predetermined concentration to coagulate and precipitate suspended matter, and the purified electrolytic solution (supernatant liquid) 2 is sent to the electrolytic solution 1. Return the mixture and drain the precipitate appropriately.

The flocculant can be added by adding its aqueous solution at a constant flow rate.
Slowly circulating the electrolyte in the treatment tank 5 is effective because it promotes mixing.

The flocculant may be added directly to the electrolyte 2 in the electrolytic cell 1.

Electrolysis was actually carried out using such a device. The electrolysis conditions were as follows.

Anode: Mild steel, plate-shaped anode: stainless steel, rotating drum type, interpolar distance IV: 15 cm Electrolytic bath: FeClz 1 mol/l Supporting electrolyte: N
H,C702 mol/1 pH H5.0 Temperature 70°C Sliding voltage: 3.3V Current density: 3.4 A/dm.

Coagulation-sedimentation treatment: In the coagulation-sedimentation treatment tank, a polyacrylamide-sodium acrylate containing 1% of acrylic acid 5, etc. The same polymer containing 20 equivalent percent of acrylic acid was selected, and a mixture of 1:2 was added continuously to a concentration of 1.5 ppm, and the electrolyte was circulated through this treatment tank.

For comparison, electrolysis was performed separately using the same electrolytic device without circulating the electrolytic solution through the sedimentation and coagulation treatment tank. The concentrations of copper, cobalt, carbon, and oxygen in the high-purity electrolytic iron electrodeposited on the cathode to a thickness of 10 mm were analyzed. The results were as shown in the table below.

〔Effect of the invention〕

According to the present invention, when producing high-purity electrolytic iron, anode residues or ferric hydroxide, etc. floating in the electrolyte are subjected to precipitation and coagulation treatment, thereby reducing the amount of impurities mixed in the electrodeposited iron. This can be significantly reduced.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing an electrolytic device for carrying out the present invention.

Claims (1)

[Claims] 1. In an electrolytic iron manufacturing method in which a cathode for iron electrodeposition and an iron anode for refining are placed opposite each other and high-purity electrolytic iron is electrodeposited on the cathode using an electrolytic solution containing a supporting electrolyte, an electrolytic cell containing a cathode and an anode. A polyacrylamide-sodium acrylate-based flocculant is added to a coagulation-sedimentation treatment tank in an electrolytic solution circulation system provided inside and/or outside the electrolytic cell, and suspended matter in the electrolytic solution is removed by precipitation. Method of manufacturing electrolytic iron.