KR102163821B1 - A method for reducing metallic oxide by using biomass containg volatile material - Google Patents

Abstract

The present invention provides a method for reducing metal oxides using biomass, and when reducing metal oxides by the reduction method according to the present invention, the reduction efficiency of carbon components and volatile substances contained in the biomass is increased, and reducing agent residues are reduced. It works.

Description

Method for reducing metal oxides using biomass containing volatile substances{A METHOD FOR REDUCING METALLIC OXIDE BY USING BIOMASS CONTAING VOLATILE MATERIAL}

The present invention relates to a method for reducing metal oxides using biomass containing volatile substances.

Various reducing agents are used to reduce metal oxides, and a solid reducing agent such as carbon and a gas reducing agent such as hydrogen or carbon monoxide, or a reducing agent in the form of a mixture thereof are mainly used.

For example, in the case of reducing metal oxides at high temperature together with coal, which is a solid reducing agent containing a volatile material (VM, volatile material) as follows, not only the reduction by carbon, but also hydrogen, carbon monoxide, which are volatile substances generated during the heating process, The reduction reaction by reducing gas also proceeds.

Fe ₂ O ₃ + 1.5C 2Fe + 1.5CO ₂

Fe ₂ O ₃ + 3H ₂ 2Fe + 3H ₂ O

Fe ₂ O ₃ + 3CO 2Fe + 3CO ₂

As described above, not only iron oxide is reduced to metallic iron by the carbon component of coal, but also iron oxide is reduced to metallic iron by hydrogen and carbon monoxide, which are volatile substances.

However, in the above case, the volatile material generated during the heating process for reduction of the metal oxide is evaporated at a relatively low temperature, so that the reduction efficiency of the volatile material may be reduced. That is, when a solid reducing agent along with a metal oxide is introduced into the reduction furnace, volatile substances are evaporated at a low temperature where the metal oxide cannot be reduced during the heating process for reduction of the metal oxide. Accordingly, the volatile material cannot reduce the metal oxide and is discharged from the reduction furnace as exhaust gas, thereby reducing the reduction efficiency of the volatile material.

In addition, when reduction is required at a relatively low temperature, fixed carbon contained in the solid reducing agent hardly participates in the reaction, and most of them remain in the form of solid carbon as a residue. Accordingly, the efficiency of the solid reducing agent is reduced, and problems such as post-treatment of solid carbon form residues occur.

Accordingly, there is a need for a method of reducing metal oxides to reduce the residuals of the reducing agent after the reduction reaction of the metal oxides and to efficiently use volatile substances in a high-temperature reduction process.

Accordingly, one aspect of the present invention provides a method for reducing metal oxides using biomass containing volatile components.

According to one aspect of the present invention, the steps of separating and obtaining volatile substances from biomass containing volatile substances, and reducing metal oxides by using the separated and obtained volatile substances and residues of a solid reducing agent from which volatile substances are partially removed. It provides a metal oxide reduction method comprising the step of.

Separation and acquisition of the volatile material may be performed at 100 to 600°C.

Prior to separating and obtaining the volatile material from the biomass, it may further include mixing the biomass and the metal oxide.

The volatile material may be separated and obtained from the mixture of the biomass and the metal oxide.

Prior to the introduction of the biomass and metal oxide, the step of removing moisture from the biomass and metal oxide may be further included.

The step of reducing the metal oxide may be performed at 600 to 1000°C.

The reduction may be performed by introducing the direction of movement of the volatile substances into the reduction furnace, the direction of the remnants of the biomass from which the volatile substances are partially removed, and the direction of inputting metal oxides through countercurrent treatment.

The method for reducing metal oxides using biomass containing volatile substances according to the present invention has an effect of increasing the reduction efficiency of volatile substances contained in the biomass and reducing biomass residues generated after reduction.

1 is a graph showing the discharge amount (g) of volatile substances discharged as the temperature rises after adding coffee foil to a heating furnace.
2 is a view showing a basic process of reducing metal oxides using biomass containing volatile substances according to the present invention.
3 is a view showing a process further including mixing the biomass and the metal oxide prior to the step of separating and obtaining a volatile material from the biomass according to an embodiment of the present invention.
4 is a view showing a process of performing a process of mixing biomass and metal oxide and a process of separating volatile substances from biomass in one step according to an embodiment of the present invention.
5 and 6 are diagrams showing a process of removing moisture contained in the biomass and metal oxide prior to introducing the biomass and metal oxide.

2 shows a schematic schematic diagram of a process of reducing metal oxides using biomass containing volatile substances. According to a preferred embodiment of the present invention, a process of separating volatile substances from biomass including volatile substances may be performed prior to reduction of metal oxides as shown in FIG. 2.

In more detail, the step of separating and obtaining volatile substances from biomass containing volatile substances, and the metal oxide may be reduced using the separated and obtained volatile substances and residues of the biomass from which volatile substances are partially removed.

The metal oxide is a generic term for various metal compounds bonded with oxygen, and includes, for example, nickel oxide, iron oxide, calcium oxide, and magnesium oxide.

As the biomass, it is preferable to use a biomass containing a large amount of volatile substances to reduce fixed carbon or ash, which is a residue after the reduction reaction as a solid reducing agent. At this time, the biomass contains 40% or more of volatile substances in a large amount, and includes, for example, coffee meal, coffee grounds, rice bran, peanut shells, sawdust, and waste wood.

When the temperature is immediately raised by mixing the biomass and the metal oxide without separating the volatile substances from the biomass, most of the volatile substances are evaporated during the heating process and discharged from the reduction furnace without reducing the metal oxide, reducing the efficiency as a reducing agent. there is a problem.

Thus, the present invention includes the step of separating and obtaining the volatile material. It can be separated and obtained by putting the biomass into a heating furnace and raising the temperature to 100 to 600°C.

Before using the biomass to directly reduce metal oxides, the biomass is heated to 100 to 600°C to separate and obtain volatile substances, and the obtained volatile substances and biomass residues from which volatile substances are partially removed The reduction efficiency of volatile substances contained in the biomass can be improved by introducing the metal oxide to the reducing step.

1 is a graph showing the discharge amount (g) of volatile substances discharged as the temperature rises after adding coffee foil to a heating furnace. As can be seen from FIG. 1, in the case of adding biomass, coffee meal, to a heating furnace and raising the temperature according to an embodiment of the present invention, volatile substances such as hydrogen and carbon monoxide are mostly discharged at 100 to 600° C. and above 600° C. At high temperatures, it can be seen that the emissions are significantly reduced.

Therefore, in the case of separating and obtaining the volatile substances discharged at 100 to 600°C separately, the reduction efficiency can be prevented from being reduced as the volatile substances are evaporated and discharged in the process of raising the temperature to 600°C or higher to reduce the metal oxide. have. If the temperature is out of the above range, it is not preferable because volatile substances are not discharged smoothly from the biomass.

The volatile material may be separated and obtained from a mixture of biomass and metal oxide as shown in FIG. 3, or a process of mixing the biomass and metal oxide and a process of separating and obtaining volatile material as shown in FIG. It can be separated and acquired while simultaneously proceeding. In this case, the mixing ratio of the biomass and the metal oxide may be adjusted according to the content of the volatile material and the composition of the metal oxide. For example, 10 kg of coffee meal and 100 kg of iron oxide powder may be mixed.

Meanwhile, prior to mixing and/or heating the biomass and the metal oxide, the step of removing moisture from the biomass and the metal oxide may be further included. When the water content of the biomass containing a large amount of metal oxides and volatile substances is high, water vapor may be generated in the process of raising the temperature to reduce the metal oxide, thereby interfering with the reduction reaction of the metal oxide.

Before the process of mixing and/or heating the metal oxide and the biomass, the biomass and the metal oxide may be dried as shown in FIGS. 5 and 6 to remove moisture. At this time, it may be dried at a temperature equal to or lower than the temperature at which volatile substances evaporate from the biomass.

The drying may be performed by firing the metal oxide, and the firing temperature may be adjusted according to the type of the metal oxide. For example, it can be calcined at 150°C to remove adsorbed water from nickelliferous limonite ((Fe,Ni)O(OH)·nH ₂ O), and goethite (α-FeO(OH) It can be fired at 400°C to remove crystal water from ).

The metal oxide may be reduced by using the obtained volatile material and the biomass residue from which the volatile material is partially removed.

The step of reducing the metal oxide may be performed at 600 to 1000°C.

When the reduction temperature of the metal oxide is less than 600°C, since the metal oxide is at a low temperature where it is difficult to reduce, the biomass that cannot reduce the metal oxide remains as a residue such as solid carbon. Therefore, a separate post-treatment process is required, which is not preferable in terms of efficiency according to the present invention. If it exceeds 1000°C, the reduction of the metal oxide does not proceed any more, which is not preferable from the economic point of view.

In this case, the reduction is performed in a reduction furnace, and the efficiency of reduction may be improved by counter-flowing the direction of movement of the volatile substances and the direction of introduction of the remnants of the biomass and metal oxides from which the volatile substances are partially removed.

For example, the reduction furnace may be a horizontal reduction furnace in the form of a rotary kiln. At one end of the horizontal reduction furnace, the remnants of the biomass and metal oxides from which the volatile substances are partially removed may be added, and the volatile substances may be introduced in a direction opposite to the direction in which the remnants of the biomass and metal oxides were introduced. have.

As described above, by separating and obtaining volatile substances separately, metal oxides can be reduced using biomass from which the volatile substances and volatile substances have been partially removed, and the process is performed in which outside air is blocked for efficiency of reduction and stability of the process. It is desirable to do it in an environment.

In this way, when the metal oxide is reduced by separating and obtaining volatile substances from the biomass containing the volatile substances of the present invention, the efficiency of the volatile substances contained in the biomass as a reducing agent can be maximized, and the process by reducing residues after reduction Can be simplified.

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

Example

1. Reduction of metal oxides

Example 1

Iron oxide (Fe ₂ O ₃ ) powder was reduced using coffee foil. The coffee meal powder used at this time is a dried powder and contains about 70% of volatile substances.

10 kg of coffee leaf and 100 kg of iron oxide powder were mixed and put into a horizontal heating furnace in the form of a rotary kiln, and the temperature of the heating furnace was raised to 500 ^o C. At this time, the heating furnace was separated from outside air, and the volatile substances generated inside the heating furnace were sent to the steam storage bin at the end of the furnace to separate and obtain.

After the separation process of volatile substances, the mixed residues of coffee ground residue and iron oxide powder were discharged in an inert atmosphere and then put into a reduction furnace at 850 ^° C. At this time, the mixed residue was added to one end of the reduction furnace, and a volatile substance was added to the other end of the reduction furnace, and countercurrent treatment was performed. The reduction time was maintained for 1 hour.

Example 2

Nickeliferous limonite ((Fe,Ni)O(OH)·nH ₂ O) powder containing nickel oxide and cobalt oxide was reduced using coffee foil.

Prior to separating the volatile substances contained in coffee leaf, it was dried at 150 ^o C to remove the adsorbed water of limonite ore, and 400 to remove the crystal water present in the high-site form (Goethite, α-FeO(OH)). ^{o Fired in} C.

100 kg of the moisture-removed limonite ore and 20 kg of coffee leaf were put into a horizontal heating furnace in the form of a rotary kiln to separate and obtain volatile substances contained in the coffee leaf under the same conditions as in Example 1, and then a reduction process was performed. .

Comparative Example 1

Except for the step of separating and obtaining volatile substances from the coffee leaf, 10 kg of coffee leaf and 100 kg of iron oxide powder were used as in Example 1, and they were immediately mixed to perform reduction under the same conditions as in Example 1.

2. Confirmation of efficiency of reduction by separation and use of volatile substances

About 50% or more of the iron oxide was reduced through the reduction process of Example 1. It was confirmed that about 95% or more of iron oxide was reduced through the reduction process of Example 2, and 100% of nickel and cobalt was reduced.

On the other hand, it was confirmed that about 22% of the iron oxide was reduced through the reduction process of Comparative Example 1.

In this way, when biomass is used as a reducing agent for the reduction process of metal oxides, biomass or biomass and biomass at a lower temperature than the reduction temperature of metal oxides prior to the reduction process than Comparative Example 1 in which biomass and metal oxides were directly added to the reduction furnace. It was confirmed that in Examples 1 and 2, in which the mixture of metal oxides was heated to separate and reduce the volatile substances, the reduction efficiency could be improved by 2 to 4 times or more. In addition, by using biomass containing a large amount of volatile substances, residues after reduction were reduced, thereby increasing the efficiency of reduction and simplifying the process.

Claims (7)

Separating and obtaining volatile substances from biomass containing volatile substances; And
Reducing the metal oxide using the separated and obtained volatile substances and the residue of the biomass from which the volatile substances are partially removed,
Prior to separating and obtaining the volatile material from the biomass, the method further comprises removing moisture from the biomass and the metal oxide. The method of claim 1,
Separation and acquisition of the volatile material is carried out at 100 to 600 ℃, metal oxide reduction method The method of claim 1,
The biomass and the metal before removing moisture from the biomass and metal oxide powder, or between removing moisture from the biomass and metal oxide powder and separating and obtaining the volatile material from the biomass A method for reducing metal oxides, further comprising the step of mixing an oxide. The method of claim 3,
The volatile material is separated and obtained from a mixture of the biomass and the metal oxide, a metal oxide reduction method. delete The method of claim 1,
The reducing step is carried out at 600 to 1000 ℃, the metal oxide reduction method. The method of claim 1,
The reduction is carried out by introducing the direction of movement of the volatile substances into a reduction furnace, the remnants of the biomass from which the volatile substances are partially removed, and the input direction of the metal oxide through countercurrent treatment.

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