KR102175428B1 - Manufacturing method of cylindrical porous iron powder - Google Patents

Abstract

The present invention relates to a method of manufacturing a needle-shaped or rod-shaped porous iron powder, specifically, the steps of preparing ferrous dihydrate by concentrating an aqueous ferrous chloride solution; Solid-liquid separating the ferrous dihydrate to prepare a ferrous dihydrate powder; Oxidizing the ferrous dihydrate powder; And it is to provide a needle-shaped or rod-shaped porous iron powder manufacturing method comprising the step of reducing the oxidized ferrous dihydrate and a needle-shaped or rod-shaped porous iron powder manufactured by the above manufacturing method.

Description

Manufacturing method of porous iron powder in the form of needles or rods {Manufacturing method of cylindrical porous iron powder}

The present invention provides a method for producing a needle-shaped or rod-shaped porous iron powder. More specifically, the present invention provides a method for producing a needle-shaped or rod-shaped porous iron powder using an aqueous ferrous chloride solution.

Conventional methods for producing iron powder include 1) a sponge-iron process (thermal reduction process) and 2) a water-atomizing process. The sponge-iron process is a process of reducing iron oxide to produce porous iron powder, and the water spraying process is a process of atomizing molten iron using a high-pressure water jet, and the iron powder produced at this time is It is a powder of high density, not porous. Also, most of the powders prepared 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 iron making process, iron oxide, etc., manufactured by using the after-pickling liquid generated after surface pickling during the iron plate manufacturing process, and the sponge-iron process The porous iron powder is characterized by a large specific surface area, high reactivity and strong reducibility, and is a material for self-lubricating bearings; Soil, groundwater, industrial wastewater purification materials (catalysts, reducing agents, etc.); Welding rod coating material; Pocket stove material; Oxygen scavenger; Raw materials for the production of iron compounds; It can be used in places such as extractants for cementation.

On the other hand, U.S. Patent Publication No. 2016-0096739 uses a process of manufacturing iron powder through an aqueous ferrous chloride solution, but when a method for manufacturing a needle-shaped or rod-shaped porous iron powder from an aqueous ferrous chloride solution 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 manufacturing method for producing iron powder having both a needle-shaped or rod-shaped characteristic and a porous characteristic.

Another aspect of the present invention is to provide iron powder prepared by the method of the present invention.

According to an aspect of the present invention, the step of preparing ferrous dihydrate by concentrating an aqueous ferrous chloride solution; Solid-liquid separating the ferrous dihydrate to prepare a ferrous dihydrate powder; Oxidizing the ferrous dihydrate powder; And there is provided a method for producing a needle-shaped or rod-shaped porous iron powder comprising the step of reducing the oxidized ferrous dihydrate.

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

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 prepared has a porous needle shape or a rod shape, so that it can be used in the field of application of the existing porous iron powder. It is possible to obtain improved filling rate, improved workability, and improved physical properties based on characteristics.

1 shows a schematic flow diagram of a method of manufacturing a needle-shaped or rod-shaped porous iron powder of the present invention.
FIG. 2 shows an SEM image of ferrous dihydrate and ferrous tetrahydrate crystals that appear when the ferrous chloride aqueous solution is concentrated according to an embodiment of the present invention.
FIG. 3 is an SEM image of iron oxide powder obtained after performing a roasting process on ferrous dihydrate obtained by concentrating an aqueous ferrous chloride solution according to an embodiment of the present invention.
4 shows an image taken by SEM of the reduced iron powder obtained after performing a reduction reaction on 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 manufacturing iron powder having both a needle-shaped or rod-shaped characteristic and a porous characteristic, and an iron powder manufactured by the above manufacturing method.

Specifically, the method for producing a needle-shaped or rod-shaped porous iron powder of the present invention includes the steps of preparing ferrous dihydrate by concentrating an aqueous ferrous chloride solution; Solid-liquid separating the ferrous dihydrate to prepare a ferrous dihydrate powder; Oxidizing the ferrous dihydrate powder; And it provides a needle-shaped or rod-shaped porous iron powder manufacturing method comprising the step of reducing the oxidized ferrous dihydrate.

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

The concentration of the aqueous ferrous chloride solution is 20 to 625 g/L, preferably 250 to 600 g/L. If the concentration is less than 20 g/L, there is a problem that the amount of ferrous chloride in the aqueous solution is small, so that the energy to evaporate moisture is excessively consumed during concentration, and the amount of precipitated ferrous dihydrate is small, and when it exceeds 625 g/L, chlorination There is a problem in that the ferrous aqueous solution is saturated or supersaturated, causing precipitation during transport.

In the step of preparing the ferrous dihydrate, the ferrous chloride aqueous solution is concentrated to precipitate supersaturated ferrous dihydrate, and the concentration may be performed, for example, by evaporation and concentration.

Meanwhile, the solid-liquid separation performed in the step of preparing the ferrous dihydrate powder may be performed by separating the precipitated ferrous dihydrate using, for example, a centrifuge, but is not limited thereto, and solid-liquid separation in the technical field such as filtration It can be done in any way that can be used for.

When the step of preparing the ferrous dihydrate is performed by evaporation and concentration, the temperature of the concentration process must be controlled, and at this time, evaporative concentration is preferably performed at a temperature of 72 to 125°C, preferably 75 to 95. It is carried out at °C temperature. When performed at a temperature of less than 72°C, ferrous tetrahydrate may be precipitated, and the ferrous tetrahydrate may precipitate in the form of a polygonal polyhedron, and at a temperature exceeding 125°C, not only iron monohydrate occurs, but also excessive energy. There is a problem of being consumed. An SEM image of the ferric tetrahydrochloride precipitated in the form of a polygonal polyhedron is shown on the left side of FIG. 2.

The step of oxidizing the ferrous dihydrate powder may be performed by a roasting process in which a pyrolysis reaction is performed in an oxygen atmosphere. In the roasting process, the reaction of ferrous dihydrate and oxygen is as follows.

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

In this case, not only Fe ₂ O ₃ but also Fe ₃ O ₄ or FeO oxide may be generated by the above reaction.

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

Furthermore, the reaction of the roasting process is 200 It can be carried out at a temperature of to 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 produced through the roasting process. Furthermore, in the case of hydrochloric acid generated during the above process, it can be used when wet-collecting to prepare an aqueous hydrochloric acid solution to prepare an aqueous ferrous chloride solution.

The step of reducing the oxidized ferrous dihydrate may be carried out through a reduction reaction of the oxidized ferrous dihydrate in a high-temperature reducing atmosphere. In this case, the reducing atmosphere may be, for example, hydrogen, carbon monoxide, or a mixed gas atmosphere thereof, and a compound capable of producing 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)

In this case, 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 reaction furnace such as a flow furnace, a rotary kiln, a belt furnace, and a drop tube furnace may be used, and an external force acts on the powder during the reaction. Therefore, it is necessary to minimize the crushing of the powder and maintain the shape of the rod.

Furthermore, the reduction reaction is 400 It can be carried out at a temperature of to 1300 ℃. Below 400℃, the reaction speed is slow, so productivity decreases. Above 1300℃, the resulting reduced iron sintering occurs excessively or the reduced iron microstructure becomes coarse. This is because there is a problem 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 performed at a temperature of preferably 700 to 1000°C.

Classification may be performed to distinguish the shape of the reduced iron generated through the reduction reaction. Furthermore, in the case of the prepared reduced iron, the reactivity may occur due to good reactivity, so the powder must be collected in an inert atmosphere.

The specific surface area of the needle-shaped or rod-shaped porous iron powder prepared by the production method of the present invention is 0.3 to 3 m ² /g, preferably 0.5 to 2.5 m ² /g. When the specific surface area of the iron powder is less than 0.3m ² /g, there is a problem of low reactivity, and when it exceeds 3m ² /g, it is easily oxidized or ignited in the atmosphere, making 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 to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Needle-shaped or rod-shaped iron powder was prepared using an aqueous solution of ferrous chloride (FeCl ₂ ) generated in the nickel hydrometallurgical process. An exemplary process is shown in FIG. 1, and a specific process is as follows.

The aqueous ferrous chloride solution (concentration is 220 g/L) was concentrated to precipitate supersaturated ferrous dihydrate (FeCl ₂ ·2H ₂ O). The precipitated ferrous dihydrate was solid-liquid separated by a centrifuge method to separate ferrous dihydrate powder. At this time, the aqueous solution was concentrated at a temperature of 80°C.

An image of the crystal of ferrous dihydrate prepared in the above step by SEM is shown in FIG. 2.

Next, the ferrous dihydrate powder was added to a rotary kiln and roasted through a pyrolysis reaction in a high temperature atmosphere containing oxygen. This produces needle-shaped or rod-shaped iron oxide.

The roasting process was performed at 700° C. for 90 minutes, and classification was performed to distinguish the shape of the produced needle-shaped or rod-shaped iron oxide. In addition, not only the Fe ₂ O ₃ but also Fe ₃ O ₄ or FeO oxide may be generated in rare cases. Meanwhile, the HCl produced together in the rotary kiln was collected with a scrubber and reused in the nickel smelting process.

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

Next, the needle-shaped or rod-shaped iron oxide was injected into a mesh belt to prepare reduced iron powder through a reduction reaction in a high-temperature gas reduction atmosphere. At this time, the gas reduction atmosphere is hydrogen or carbon monoxide atmosphere.

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

The resulting needle-shaped or rod-shaped reduced iron powder was a powder having a length of about 500 μm and an aspect ratio of about 5, and a specific surface area of about 2.3 m ² /g. In this case, since the prepared reduced iron has good reactivity and can cause reoxidation, the powder must be collected in an inert atmosphere.

Fig. 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 the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention described in the claims. It will be obvious to those of ordinary skill in the field.

Claims (10)

Preparing ferrous dihydrate by concentrating an aqueous ferrous chloride solution at a temperature of 72 to 125°C;
Solid-liquid separating the ferrous dihydrate to prepare a ferrous dihydrate powder;
Oxidizing the ferrous dihydrate powder; And
Needle-shaped or rod-shaped porous iron powder manufacturing method comprising the step of reducing the oxidized ferrous dihydrate.
The method of claim 1, wherein the concentration of the aqueous ferrous chloride solution is 20 to 625 g/L.
The method of claim 1, wherein the concentration of the ferrous chloride aqueous solution is performed by evaporation and concentration.
According to claim 1, The step of oxidizing the ferrous dihydrate powder is carried out by roasting at a temperature of 200 to 1300 °C in an oxygen atmosphere, needle-shaped or rod-shaped porous iron powder manufacturing method.
The method of claim 1, wherein the reducing the ferrous dihydrate powder is performed at a temperature of 400 to 1300°C under a reducing atmosphere.
The method according to claim 5, wherein the reducing atmosphere is hydrogen, carbon monoxide, or a mixed gas atmosphere thereof.
The method of claim 6, wherein the reducing the ferrous dihydrate powder is performed at a temperature of 600 to 800°C in a hydrogen atmosphere.
The method of claim 6, wherein the reducing the ferrous dihydrate powder is performed at a temperature of 700 to 1000°C in a carbon monoxide atmosphere.
A needle-shaped or rod-shaped porous iron powder manufactured by the manufacturing method of any one of claims 1 to 8.
The method of claim 9, wherein the iron powder has a specific surface area of 0.3 to 3m ² /g, needle-shaped or rod-shaped porous iron powder.

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