WO2020096293A1 - Method for manufacturing needle-shaped or rod-shaped porous iron powder and needle-shaped or rod-shaped porous iron powder manufactured thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a needle-shaped or rod-shaped porous iron powder. Specifically, the present invention provides a method for manufacturing a needle-shaped or rod-shaped porous iron powder and a needle-shaped or rod-shaped porous iron powder manufactured thereby, the method comprising the steps of: preparing a ferrous dichloride chloride by concentrating a ferrous chloride aqueous solution; solid-liquid separating the ferrous dichloride to prepare ferrous dichloride powder; oxidizing the ferrous dichloride powder; and reducing the oxidized ferrous dichloride.

Description

A method for manufacturing a needle or rod-shaped porous iron powder, and a needle or rod-shaped porous iron powder produced thereby

The present invention provides a method for manufacturing a needle or rod-shaped porous iron powder, and a needle or rod-shaped porous iron powder produced thereby. More specifically, the present invention provides a method for producing a needle-shaped or rod-shaped porous iron powder using an aqueous solution of ferric chloride, and a needle-shaped or rod-shaped porous iron powder produced thereby.

The conventional method for manufacturing iron powder is 1) a sponge-iron process (sponge-iron process) and a water-atomizing process. The sponge-iron process is a process of reducing iron oxide to form a porous iron powder, and the water spray process is an atomizing process of molten iron using a high-pressure water jet, wherein the iron powder produced at this time is It is a dense powder that is not porous. Also, most of the powders produced in this way have an angular cube shape, a spherical shape, or a heterogeneous shape.

The iron oxide used in the sponge-iron process can be used as a raw material such as iron ore or powder generated during the ironmaking process, iron oxide produced using a pickling solution generated after surface pickling during the iron plate manufacturing process, and produced by the sponge-iron process Porous iron powder is characterized by a large specific surface area, high reactivity, and strong reducibility, making it a self-lubricating bearings material; Soil, groundwater, industrial wastewater purification materials (catalysts, reducing agents, etc.); Welding rod coating material; Pocket stove material; Deoxidizers; Raw materials for the production of iron compounds; It can be used in places such as extractants for cementation.

On the other hand, US Patent Publication No. 2016-0096739 uses a process for producing iron powder through an aqueous solution of ferric chloride, but when a method of manufacturing a needle or rod-shaped porous iron powder from an aqueous solution of ferric chloride is developed, iron powder is used. It is expected to be more useful in the field of use.

One aspect of the present invention is to provide a method for manufacturing an iron powder having both needle-like or rod-like features and porous characteristics.

According to another aspect of the present invention, it is to provide an iron powder produced by the manufacturing method of the present invention.

According to an aspect of the present invention, a ferrous chloride aqueous solution is concentrated to prepare ferrous dihydride; Preparing the ferric dihydrate powder by solid-liquid separation of the ferric dichloride; Oxidizing the ferric dihydrate powder; And it provides a needle or rod-shaped porous iron powder manufacturing method comprising the step of reducing the oxidized ferric monohydrate.

According to another aspect of the present invention, a needle or rod-shaped porous iron powder produced by the above manufacturing method is provided.

According to the process of the present invention, it is possible to mass-produce iron powder from an aqueous solution of iron chloride, and the iron powder thus manufactured has a porous needle-like or rod-like shape, and thus can be used in the existing application of porous iron powder, as well as of rod-like powder It is possible to obtain an improvement in filling rate based on characteristics, improvement in workability, and improvement in physical properties.

1 shows a schematic flow chart of a method for manufacturing a needle or rod-shaped porous iron powder of the present invention.

Figure 2 shows an image taken by SEM of ferric dichloride and ferrous tetrachloride crystals that appear when the ferric chloride aqueous solution is concentrated according to an embodiment of the present invention.

Figure 3 shows an image taken by SEM of the iron oxide powder obtained after performing the roasting process on ferrous dichloride obtained by concentration of aqueous ferric chloride solution according to an embodiment of the present invention.

Figure 4 shows an image taken by SEM of the reduced iron powder obtained after performing a reduction reaction to the iron oxide powder according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention provides a manufacturing method for producing iron powder having both needle-like or rod-like characteristics and porous characteristics, and an iron powder produced by the manufacturing method.

Specifically, the method of manufacturing a needle or rod-shaped porous iron powder of the present invention comprises the steps of: concentrating an aqueous ferric chloride solution to produce ferric dihydride; Preparing the ferric dihydrate powder by solid-liquid separation of the ferric dichloride; Oxidizing the ferric dihydrate powder; And it provides a needle or rod-shaped porous iron powder manufacturing method comprising the step of reducing the oxidized ferric monohydrate.

The raw material of the ferric chloride aqueous solution may be a thick solution generated after the pickling process for removing oxides on the surface during the iron plate manufacturing process, a thick solution generated during other processes or an aqueous solution in which iron is dissolved in hydrochloric acid, and the ferric chloride aqueous solution is saturated or supersaturated. It is preferably an aqueous solution that is not.

The concentration of the aqueous ferric chloride solution is 20 to 625 g / L, preferably 250 to 600 g / L. When the concentration is less than 20 g / L, the amount of ferric chloride in the aqueous solution is small, and thus the energy to evaporate moisture during concentration is excessively consumed, and there is also a problem that the amount of ferrous dihydride precipitated is small, and when it exceeds 625 g / L, chloride There is a problem that precipitation occurs during transport due to saturated or supersaturated aqueous solution of ferrous iron.

In the manufacturing of the ferric dichloride, the ferric chloride aqueous solution is concentrated to precipitate supersaturated ferric dichloride, where concentration may be performed, for example, by evaporative concentration.

On the other hand, the solid-liquid separation performed in the step of preparing the ferric dihydride powder can be separated, for example, the precipitated ferric dichloride using a centrifugal separator, but is not limited thereto, filtration, and solid-liquid separation in the art It can be carried out by any method that can be used for.

When the step of preparing the ferric dichloride is carried out by evaporation concentration, the temperature of the concentration process should be controlled, and evaporation concentration is preferably performed at, for example, 72 to 125 ° C, preferably 75 to 95 It is carried out at a temperature of ℃. When carried out at a temperature of less than 72 ° C, ferrous tetrachloride may precipitate, and the ferric tetrachloride has a problem of precipitating in the form of a rectangular polyhedron, and at temperatures exceeding 125 ° C, not only iron monochloride is generated, but energy is excessive. There is a problem to be wasted. The image taken by SEM of ferric tetrachloride precipitated in the form of the polygonal polyhedron is shown in FIG. 2.

The step of oxidizing the ferric dihydride powder may be performed by a roasting process in which a thermal decomposition reaction is performed in an oxygen atmosphere. The reaction of ferrous dihydride and oxygen in the roasting process is as follows.

2 (FeCl ₂ H ₂ O) + 1 / 2O ₂ → Fe ₂ O ₃ + 4HCl (g)

At this time, in addition to Fe ₂ O ₃ , rarely Fe ₃ O ₄ or FeO oxide may be generated through the above reaction.

In addition, the roasting process is not limited, but a reactor such as a flow path, a rotary kiln, a belt, or a drop tube can be used, and external force acts on the powder during the reaction. Therefore, it is necessary to minimize the crushing of the powder to maintain the shape of the rod.

Furthermore, the reaction of the roasting process is 200 It may be carried out at a temperature of 1300 ℃. This is because iron oxide is not generated below 200 ° C and iron oxide sintering occurs above 1300 ° C, making it difficult to obtain iron oxide in a desired shape. Preferably it can be carried out at a temperature of 500 to 800 ℃.

Classification may be performed to distinguish the shape of the iron oxide generated through the roasting process. Furthermore, in the case of hydrochloric acid generated during the above process, it can be used to make a hydrochloric acid aqueous solution by wet capture to make an aqueous ferric chloride solution.

The step of reducing the oxidized ferric dihydrate may be performed through a reduction reaction in the high temperature reducing atmosphere. At this time, the reducing atmosphere may be, for example, hydrogen, carbon monoxide or a mixed gas atmosphere thereof, and a compound capable of forming hydrogen, carbon monoxide or a mixed gas thereof through a reaction such as decomposition may be used as a reducing agent. The reduction reaction is, for example, as follows.

Fe ₂ O ₃ + 3H ₂ (g) or 3CO (g) → 2Fe + 3H ₂ O (g) or 3CO ₂ (g)

At this time, the Fe ₃ O ₄ or FeO oxide rarely generated in the oxidation step undergoes a reduction reaction through the following reaction.

FeO + H ₂ (g) or CO (g) → Fe + H ₂ O (g) or CO ₂ (g)

Fe ₃ O ₄ + 4H ₂ (g) or 4CO (g) → 3Fe + 4H ₂ O (g) or 4CO ₂ (g)

In addition, the reduction reaction is not limited, but a reactor such as a flow path, a rotary kiln, a belt, or a drop tube can be used, and external force acts on the powder during the reaction. Therefore, it is necessary to minimize the crushing of the powder to maintain the shape of the rod.

Furthermore, the reduction reaction is 400 It may be carried out at a temperature of 1300 ℃. Below 400 ℃, the reaction rate is slow and productivity decreases. Above 1300 ℃, sintering of the reduced iron generated excessively or the reduced iron microstructure is coarsened. This is because a problem arises that the porous tissue disappears. When the reducing atmosphere is a hydrogen atmosphere, the reduction reaction may be preferably performed at a temperature of 600 to 800 ° C, and when the reducing atmosphere is a carbon monoxide atmosphere, the reduction reaction may be preferably performed at a temperature of 700 to 1000 ° C.

Classification may be performed to distinguish the shape of the reduced iron generated through the reduction reaction. Furthermore, since the reduced iron produced has good reactivity and re-oxidation may occur, the powder must be collected in an inert atmosphere.

The specific surface area of the acicular or rod-shaped porous iron powder produced by the production method of the present invention is 0.3 to 3 m ² / g, and preferably 0.5 to 2.5 m ² / g. When the specific surface area of the iron powder is less than 0.3 m ² / g, there is a problem of low reactivity, and when it exceeds 3 m ² / g, oxidation or ignition occurs easily in the atmospheric state, which makes it difficult to handle during the process.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples for helping the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Needle-shaped or rod-shaped iron powders were prepared by using an aqueous solution of ferric chloride (FeCl ₂ ) generated in the nickel wet smelting process. An exemplary process is shown in FIG. 1, and a specific process is as follows.

The aqueous solution of ferric chloride (concentration is 220 g / L) was concentrated to precipitate supersaturated ferric dihydrate (FeCl ₂ · 2H ₂ O). The precipitated ferric dichloride was subjected to solid-liquid separation by centrifugation to separate ferric dichloride powder. At this time, concentration of the aqueous solution was carried out at 80 ℃ temperature.

The image taken by SEM of the crystal of ferric dihydride prepared in the above step is shown in FIG. 2.

Next, the ferric dihydride powder was introduced into a rotary kiln and roasted through a pyrolysis reaction in a high temperature atmosphere containing oxygen. As a result, needle or rod-shaped iron oxide is produced.

The roasting process was performed at 700 ° C. for 90 minutes, and classification was performed to distinguish the shape of the produced iron oxide in the form of needles or rods. In addition, Fe ₃ O ₄ or FeO oxide may be rarely generated as well as Fe ₂ O ₃ . Meanwhile, HCl produced together in the rotary kiln was collected by a scrubber and reused in a nickel smelting process.

3 shows an image of the oxidized iron powder produced through the above process by SEM.

Next, iron iron powder was prepared through a reduction reaction in a high-temperature gas reduction atmosphere by injecting the needle or rod-like iron oxide into a mesh belt. At this time, the gas reduction atmosphere is a hydrogen or carbon monoxide atmosphere.

The reduction reaction was performed at 750 ° C. for 60 minutes, and classification was performed to classify the shape of the produced iron oxide in the form of needles or rods, and divided into needle or rod-shaped reduced iron powders and fine reduced iron powders.

The resulting needle or rod-shaped reduced iron powder was a powder having a length of about 500 μm and an expected ratio of about 5, and a specific surface area of about 2.3 m ² / g. At this time, in the case of the reduced iron produced, the reactivity is good and re-oxidation may occur, so the powder must be collected in an inert atmosphere.

4 shows an image of the reduced iron powder produced through the above process by SEM.

Although the embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereto, and it is possible that various modifications and variations are possible without departing from the technical spirit of the present invention as set forth in the claims. It will be apparent to those of ordinary skill in the field.

Claims (10)

1. Concentrating the aqueous ferric chloride solution to produce ferric dichloride;

   Preparing the ferric dihydrate powder by solid-liquid separation of the ferric dichloride;

   Oxidizing the ferric dihydrate powder; And

   A method of manufacturing a porous iron powder in a needle or rod shape comprising the step of reducing the oxidized ferric monohydrate.
2. According to claim 1, The concentration of the aqueous solution of ferric chloride is 20 to 625g / L, needle or rod-shaped porous iron powder manufacturing method.
3. According to claim 1, Concentration of the aqueous solution of ferric chloride is carried out by evaporation and concentration at a temperature of 72 to 125 ℃, needle or rod-shaped porous iron powder manufacturing method.
4. The method of claim 1, wherein the step of oxidizing the ferric dihydride powder is performed by roasting at a temperature of 200 to 1300 ° C. in an oxygen atmosphere.
5. The method of claim 1, wherein the step of reducing the ferric dihydride powder is performed at a temperature of 400 to 1300 ° C. under a reducing atmosphere.
6. The method of claim 5, wherein the reducing atmosphere is hydrogen, carbon monoxide, or a mixed gas atmosphere thereof.
7. The method of claim 6, wherein the step of reducing the ferric dihydride powder is performed at a temperature of 600 to 800 ° C. in the case of a hydrogen atmosphere.
8. The method of claim 6, wherein the step of reducing the ferric dihydride powder is performed at a temperature of 700 to 1000 ° C. in a carbon monoxide atmosphere.
9. A needle or bar-shaped porous iron powder produced by the method of any one of claims 1 to 8.
10. The porous iron powder according to claim 9, wherein the iron powder has a specific surface area of 0.3 to 3 m ² / g.

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