JP7700527B2 - Reduction treatment method and reduction treatment device - Google Patents

Description

The present invention relates to a reduction processing method and a reduction processing device.

For example, since ores are usually oxidized and contain a lot of moisture, the ores have traditionally been dried and reduced before being melted in an electric furnace or the like (see, for example, Patent Document 1).

JP 2014-141719 A

When reducing materials such as ores, carbon components, such as coal, are used as a reducing agent, but since the inside of the furnace is usually a reducing atmosphere, the carbon is not sufficiently oxidized and exhaust gas containing carbon monoxide may be generated. It is possible to use an oxidation catalyst to purify such exhaust gas, but the exhaust gas usually also contains sulfur components due to the raw materials such as ores. For this reason, when exhaust gas containing sulfur components is brought into contact with an oxidation catalyst, there is a problem that the performance of the oxidation catalyst decreases.

In view of the problems inherent in the above-mentioned conventional techniques, one aspect of the present invention aims to provide a reduction treatment method that can reduce the concentration of sulfur components in exhaust gas.

In order to solve the above problem, according to one aspect of the present invention,
A reduction treatment method for reducing a material containing a sulfur component in a rotary kiln, comprising:
A scoop feeder is provided in the middle of the rotary kiln, and a reaction treatment agent adding step is provided in which a reducing agent and a desulfurizing agent are added through the scoop feeder;
The reducing agent is coal, the desulfurizing agent is quicklime,
The reduction treatment method includes countercurrent heating the material to be reduced with combustion heat from a burner of the rotary kiln .

According to one aspect of the present invention, a reduction treatment method can be provided that can reduce the concentration of sulfur components in exhaust gas.

FIG. 1 is a schematic diagram of a reduction treatment device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA' in FIG.

Hereinafter, the form for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and substitutions can be made to the following embodiment without departing from the scope of the present invention.
[Reduction Treatment Method]
The reduction treatment method of this embodiment is a reduction treatment method in which the material to be reduced is reduced in a rotary kiln, and can include a reactive treatment agent addition step in which a scoop feeder is provided midway through the rotary kiln and a reducing agent and a desulfurizing agent are added via the scoop feeder.

The reducing agent may be coal and the desulfurizing agent may be quicklime.
(1) Regarding the reduced material The reduced material to be subjected to the reduction treatment method of the present embodiment is not particularly limited. However, since the reduction treatment method of the present embodiment can reduce the concentration of sulfur components in exhaust gas, the reduced material preferably contains sulfur components.

Examples of the material to be reduced include various types of ores. In particular, metal ores that are required to be refined generally contain a lot of moisture and are oxidized. According to the reduction treatment method of this embodiment, drying and reduction can be efficiently performed, so it is preferable that the material to be reduced includes metal ores. Note that the material to be reduced may be composed of metal ores.

The metals contained in the metal ore are not particularly limited, but it is preferable that the metals contain non-ferrous metals, and it is more preferable that the metal ore contains one or more metals selected from nickel, zinc, etc.

The material to be reduced may be pre-dried in advance to reduce or remove some of the adhering moisture.
(2) Reactive Treatment Agent Addition Step The reduction treatment method of the present embodiment may have a reactive treatment agent addition step as described above.

In the reactive treatment agent addition process, a scoop feeder is provided midway through the rotary kiln, and the reducing agent and desulfurizing agent can be added through the scoop feeder. In the reactive treatment agent addition process, the reducing agent and desulfurizing agent can be added to the material to be reduced being heated in the rotary kiln as described above.

The reducing agent and the desulfurizing agent can be added at different times, so the reaction treatment agent supply process can also have a reducing agent supply process for supplying a reducing agent and a desulfurizing agent supply process for supplying a desulfurizing agent.

In the reduction treatment method of this embodiment, after carrying out the reactive treatment agent addition process, the reduced material, reducing agent, and desulfurizing agent can be mixed and heated in a rotary kiln. At this time, the reduction treatment method of this embodiment can carry out a reduction drying process in which the reduced material is reduced and dried. In addition, the reduction treatment method of this embodiment can carry out a desulfurization process in which the sulfur components contained in the exhaust gas generated from the reduced material, etc. during the reduction drying process are reduced and removed by the desulfurizing agent.

Hereinafter, a configuration example of a rotary kiln that can be used in the reduction treatment method of this embodiment and a reactive treatment agent will be described.
(2-1) Rotary Kiln A configuration example of a rotary kiln in which the reduction treatment method of this embodiment can be suitably carried out will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of the rotary kiln, and Figure 2 is a cross-sectional view taken along line AA' in Figure 1.

The body 100 of the rotary kiln 10 shown in FIG. 1 has a substantially cylindrical shape, and is configured to be rotatable around a central axis CA. The rotary kiln 10 is inclined downward from the inlet end 101, which is one end in the longitudinal direction, to the discharge end 102, which is the other end in the longitudinal direction. Therefore, the material to be reduced introduced from the inlet end 101 side moves inside the rotating body 100 to the discharge end side. As described later, a burner 14 is provided on the discharge end 102 side, and the combustion heat of the fossil fuel burned by the burner moves in the opposite direction to the movement of the material to be reduced, that is, from the discharge end 102 side to the inlet end 101 side, thereby countercurrent heating the material to be reduced.

The rotary kiln 10 has an inlet 11 at the inlet end 101, which is one end in the longitudinal direction, and the material to be reduced can be introduced into the body part 100 from the inlet 11. The material to be reduced has already been explained, so an explanation will be omitted here. In addition, an exhaust pipe 12 is provided at the inlet end 101, and exhaust gas generated in the rotary kiln can be exhausted from the exhaust pipe 12. It is preferable that the exhaust pipe 12 is connected to, for example, a catalyst tower 30 described later, so that carbon monoxide in the exhaust gas can be reduced and removed.

The other end of the rotary kiln 10 in the longitudinal direction, that is, the discharge end 102, is provided with a discharge chute, that is, the discharge port 13, and can be configured to discharge the reduced material that has completed the reduction process inside the body part 100. The reduced material that has completed the reduction process can be transported to an electric furnace or the like for other processing as necessary. In addition, the discharge end 102 is provided with a burner 14, which can burn fossil fuels such as heavy oil to heat the reduced material and the like that has been put into the body part 100 of the rotary kiln 10.
(Scoop feeder)
The rotary kiln 10 may have a scoop feeder midway, i.e., between the inlet end 101 and the outlet end 102. Figure 2 shows a cross section at the position where the scoop feeder is provided, i.e., a cross section taken along line A-A'.

As shown in FIG. 2, the rotary kiln 10 can have a rotating body 100 and an outer shell 110 that covers the body 100. The outer shell 110 does not need to be provided to cover the entire surface of the body 100, and can be provided only where necessary, such as where a scoop feeder is provided, as shown in FIG. 1.

The material to be reduced 21 is introduced into the body 100 through the inlet 11, and can move toward the discharge end 102 as the body 100 rotates.

A space 120 is formed between the body 100 and the outer shell 110, and a reducing agent and a reaction treatment agent 22, which is a desulfurizing agent, can be supplied to the space 120 through a reaction treatment agent supply port 111 provided in the outer shell 110. A reaction treatment agent supply means 221 for supplying the reaction treatment agent as required can be connected to the reaction treatment agent supply port 111.

The reactive processing agent supply means 221 may have a reducing agent supply means for supplying a reducing agent and a desulfurizing agent supply means for supplying a desulfurizing agent, but may also be a single reactive processing agent supply means for supplying a reactive processing agent in which, for example, the reducing agent and the desulfurizing agent are premixed.

The configuration of the reactive processing agent supply means 221 is not particularly limited, and may be configured so that the opening of the opening provided on the reactive processing agent supply port 111 side can be adjusted according to the amount of reactive processing agent supplied, and the amount of reactive processing agent that falls freely through the opening can be adjusted. In addition, the reactive processing agent supply means may have a conveying means such as a screw conveyor, and the conveying speed of the reactive processing agent by the conveying means can be adjusted, so that the amount of reactive processing agent supplied can be adjusted by the conveying speed.

The scoop feeder 130 can be formed, for example, of an L-shaped pipe bent between the tip 131 and the straight section 132. The scoop feeder 130 can rotate together with the body section 100, for example, clockwise (right-handed) as shown by the arrow in FIG. 2. During such rotation, the tip 131 can scoop up the reducing agent and desulfurizing agent supplied to the space section 120, and the scooped reducing agent and desulfurizing agent can be passed through the straight section 132 and fed into the body section 100.

In the rotary kiln 10, the location where the scoop feeder is installed is not particularly limited, and it can be installed at any location depending on the temperature distribution inside the body portion 100 of the rotary kiln 10, etc.

For example, from the viewpoint of allowing the reduction reaction and desulfurization reaction to proceed sufficiently, the scoop feeder can be provided in a location where the temperature inside the body 100 is 900°C or higher and 1200°C or lower. This is because by providing the scoop feeder in a location where the temperature inside the body 100 is 900°C or higher and 1200°C or lower and supplying the reaction treatment agent, the fixed carbon in the coal, which is the reducing agent contained in the reaction treatment agent, can be efficiently combusted.

The desulfurization reaction proceeds at lower temperatures than the reduction reaction, for example at temperatures between 100°C and 200°C. For this reason, for example, scoop feeders can be provided at two locations along the longitudinal direction of the rotary kiln 10. Specifically, a scoop feeder for adding a desulfurization agent and a scoop feeder for adding a reducing agent can be provided separately.

The location where the scoop feeder is provided is not particularly limited as described above. For example, the distance L110 from the discharge end 102 to the end of the outer shell 110 on the side of the introduction end 101 where the scoop feeder is provided is preferably 5% to 95% of the longitudinal length L100 of the body 100 of the rotary kiln 10, more preferably 10% to 90%.
(Operating conditions of rotary kiln)
The operating conditions of the rotary kiln are not particularly limited and can be arbitrarily selected depending on the type of material to be reduced, etc.

For example, the temperature of the material to be reduced in the furnace at the discharge end 102 of the rotary kiln 10 can be set to 700°C or higher and 900°C or lower, and the temperature of the exhaust gas in the furnace at the inlet end 101 can be set to 250°C or higher and 400°C or lower.

By setting the temperature of the material to be reduced in the furnace at the discharge end 102 of the rotary kiln 10 to 700°C or higher and the exhaust gas temperature in the furnace at the inlet end 101 to 250°C or higher, the fixed carbon in the coal, which is the reducing agent supplied, can be sufficiently burned and the reduction process can be carried out efficiently. In addition, by setting the temperature of the material to be reduced in the furnace at the discharge end 102 of the rotary kiln 10 to 900°C or lower and the exhaust gas temperature in the furnace at the inlet end 101 to 400°C or lower, the generation of slag can be suppressed and the adhesion of slag to the furnace walls of the rotary kiln 10 can be suppressed.

The rotation speed of the rotary kiln 10, i.e., the rotation speed of the body portion 100 that constitutes the rotary kiln 10, is not particularly limited, but it is preferably, for example, about 0.5 rpm or more and 1.5 rpm or less.

By setting the rotation speed of the rotary kiln 10 to 0.5 rpm or more, the stirring force inside the rotary kiln 10 can be sufficiently increased, allowing the reaction to proceed sufficiently while exposing the reaction treatment agents, such as reducing agents, that were added during the reaction.

In addition, by setting the rotation speed of the rotary kiln to 1.5 rpm or less, it is possible to prevent the materials to be reduced and the like introduced into the rotary kiln 10 from flying up within the rotary kiln 10 and being discharged as dust from the introduction end 101 together with the exhaust gas.
(2-2) Regarding the reactive treatment agent In the reactive treatment agent supplying step, coal as a reducing agent and quicklime as a desulfurizing agent can be supplied as the reactive treatment agent.
(Regarding reducing agents)
Coal can be suitably used as the reducing agent. Note that the reducing agent may contain reducing agent components other than coal, or may be composed only of coal.

It is preferable that moisture is sufficiently removed from the reducing agent, and for example, the moisture content is preferably 2% by mass or more and 5% by mass or less. By removing moisture from the reducing agent, the time required for the moisture to evaporate after the reducing agent is supplied to the rotary kiln can be suppressed, and the fixed carbon contained in the reducing agent can be efficiently burned.
(About desulfurizing agents)
It is believed that quicklime, which is a desulfurizing agent, reacts as shown in the following formulas (1) to (3) to achieve desulfurization. In the reduction treatment method of this embodiment, the material to be reduced is also dried, so that the atmosphere in the rotary kiln contains sufficient moisture, and the water in formula (1) is supplied from that atmosphere.

CaO+ _H2O →Ca(OH) ₂ ...(1)
SO ₂ +Ca(OH) ₂ →CaSO ₃・1/2H ₂ O+1/2H ₂ O...(2)
CaSO ₃・1/2H ₂ O+1/2O ₂ +3/2H ₂ O→CaSO ₄・2H ₂ O...(3)
The desulfurizing agent may contain slaked lime Ca(OH) ₂ and the like in addition to quicklime, but is preferably composed only of quicklime from the viewpoint of increasing the drying efficiency of the reduced material.

The reducing agent and the desulfurizing agent can be mixed in advance and fed into the rotary kiln 10 as a reaction treatment agent, but they can also be fed into the rotary kiln 10 separately without being mixed.

The particle size of the reducing agent and desulfurizing agent is not particularly limited, and it is preferable to adjust the particle size so that the reactive treatment agent can be dispersed in the reduced material when the reducing agent and the reactive treatment agent are mixed with each other by the rotation of the rotary kiln after being fed into the rotary kiln.

As described above, by adding the reactive treatment agent, which is a reducing agent and a desulfurizing agent, in the reactive treatment agent addition step, it is possible to reduce the sulfur components in the exhaust gas as well as reduce the materials to be reduced.
(3) Exhaust Gas Treatment Step The reduction treatment method of the present embodiment may also have an exhaust gas treatment step in which the exhaust gas from the rotary kiln is introduced into a catalyst tower containing an oxidation catalyst to treat the exhaust gas.

In the exhaust gas treatment process, as shown in FIG. 1, exhaust gas discharged from the exhaust pipe 12 is introduced into the catalytic tower 30, which reduces and removes carbon monoxide in the exhaust gas.

The oxidation catalyst may be any known catalyst capable of reducing or removing carbon monoxide, and is not particularly limited.

As described above, the reduction treatment method of this embodiment involves carrying out a reactive treatment agent addition process, adding a desulfurizing agent to the material to be reduced, and then drying and reducing the material. This reduces the content of sulfur components in the exhaust gas, preventing the oxidation catalyst from becoming poisoned.

According to the reduction treatment method of the present embodiment described above, since the desulfurizing agent is added to the material to be reduced in the reaction treatment agent addition step, the sulfur components in the exhaust gas can be reduced. Therefore, when exhaust gas treatment is performed to reduce carbon monoxide in the exhaust gas, poisoning of the oxidation catalyst can be suppressed, and the exhaust gas can be treated efficiently.
[Reduction treatment device]
The reduction treatment device of this embodiment is a reduction treatment device that reduces materials to be reduced.

The reduction treatment device of this embodiment can have a rotary kiln, a scoop feeder arranged between both longitudinal ends of the rotary kiln, and a reaction treatment agent supplying means for supplying a reducing agent and a desulfurizing agent provided in the scoop feeder. The reducing agent is coal, and the desulfurizing agent is quicklime.

The reduction processing device of this embodiment can implement the reduction processing method described above. Therefore, the items that have already been explained will not be explained again.

The material to be reduced that is supplied to the reduction treatment device of this embodiment is not particularly limited, but since the reduction treatment device of this embodiment can reduce the concentration of sulfur components in the exhaust gas, it is preferable that the material to be reduced contains sulfur components.

Examples of the material to be reduced include various types of ores. In particular, metal ores that are required to be refined generally contain a lot of moisture and are oxidized. According to the reduction treatment method of this embodiment, drying and reduction can be efficiently performed, so it is preferable that the material to be reduced includes metal ores. Note that the material to be reduced may be composed of metal ores.

The metals contained in the metal ore are not particularly limited, but it is preferable that the metals contain non-ferrous metals, and it is more preferable that the metal ore contains one or more metals selected from nickel, zinc, etc.

In addition, the material to be reduced can be pre-dried in advance to reduce or remove some of the adhering moisture.

The reduction treatment device of this embodiment can have a rotary kiln, a scoop feeder, and a reactive treatment agent supply means, as described with reference to Figures 1 and 2.

Rotary kilns and scoop feeders have already been explained, so we will not go into detail here.

The reactive treatment agent supply means 221 need only be configured to supply the reactive treatment agents, ie, the reducing agent and the desulfurizing agent, and the details are not particularly limited.

The reactive processing agent supply means 221 may have a reducing agent supply means for supplying a reducing agent and a desulfurizing agent supply means for supplying a desulfurizing agent, but may also be a single reactive processing agent supply means for supplying a reactive processing agent in which, for example, the reducing agent and the desulfurizing agent are premixed.

The configuration of the reactive processing agent supply means 221 is not particularly limited, and may include, for example, a storage container and a supply amount adjustment means.

The supply amount adjustment means may be configured, for example, so that the opening of an opening provided on the reaction treatment agent supply port 111 side of the storage container can be adjusted in accordance with the supply amount of the reaction treatment agent, thereby adjusting the supply amount of the reaction treatment agent that falls freely through the opening. The supply amount adjustment means may also be configured to have a transport means such as a screw conveyor, and to adjust the transport speed of the reaction treatment agent by the transport means, thereby adjusting the supply amount of the reaction treatment agent by the transport speed.

In FIG. 1, an example is shown in which the reactive treatment agent supply means 221 is provided at the reactive treatment agent supply port 111, but this is not limited to the above embodiment. For example, the reactive treatment agent supply means 221 and the reactive treatment agent supply port 111 may be connected by a pipe, and the two components may be separated from each other.

The reaction treatment agent supplying means may also have a reducing agent supplying means for supplying a reducing agent, and a desulfurizing agent supplying means for supplying a desulfurizing agent. By having a reducing agent supplying means and a desulfurizing agent supplying means, it is possible to control the supply amounts of the reducing agent and the desulfurizing agent, respectively. Each supplying means may have, for example, the configuration described for the reaction treatment agent supplying means, and the reducing agent supplying means and the desulfurizing agent supplying means may have the same configuration or different configurations.

The reducing agent and desulfurizing agent have already been explained, so we will not explain them here.

The reduction treatment device of this embodiment can also have a catalyst tower containing an oxidation catalyst that treats the exhaust gas from the rotary kiln.

The oxidation catalyst may be any known catalyst capable of reducing or removing carbon monoxide, and is not particularly limited.

As described above, the reduction treatment device of this embodiment adds a reactive treatment agent, adds a desulfurization agent to the material to be reduced, and performs drying and reduction. This reduces the amount of sulfur components in the exhaust gas, preventing the oxidation catalyst from becoming poisoned.

According to the reduction treatment device of this embodiment described above, the desulfurization agent is added to the material to be reduced by the reaction treatment agent adding means, so that the sulfur components in the exhaust gas can be reduced. Therefore, when exhaust gas treatment is performed to reduce carbon monoxide in the exhaust gas, the poisoning of the oxidation catalyst can be suppressed, and the exhaust gas can be treated efficiently.

10 Rotary kiln 130 Scoop feeder 30 Catalyst tower

Claims (6)

A reduction treatment method for reducing a material containing a sulfur component in a rotary kiln, comprising:
A scoop feeder is provided in the middle of the rotary kiln, and a reaction treatment agent adding step is provided in which a reducing agent and a desulfurizing agent are added through the scoop feeder;
The reducing agent is coal, the desulfurizing agent is quicklime,
The reduction treatment method in which the material to be reduced is countercurrently heated by combustion heat from a burner of the rotary kiln . The reduction treatment method according to claim 1, further comprising an exhaust gas treatment process in which the exhaust gas from the rotary kiln is introduced into a catalytic tower containing an oxidation catalyst to treat the exhaust gas. The reduction method according to claim 1 or claim 2, wherein the material to be reduced includes metal ore. A reduction treatment device for reducing a material to be reduced that contains a sulfur component ,
Rotary kiln and
A scoop feeder disposed between both ends of the rotary kiln in the longitudinal direction;
A reaction treatment agent supplying means for supplying a reducing agent and a desulfurizing agent provided in the scoop feeder,
The reducing agent is coal, the desulfurizing agent is quicklime,
The reduction treatment device in which the material to be reduced is countercurrently heated by combustion heat from a burner of the rotary kiln . The reduction treatment device according to claim 4, which has a catalyst tower containing an oxidation catalyst for treating exhaust gas from the rotary kiln. The reduction treatment device according to claim 4 or claim 5, wherein the material to be reduced includes metal ore.

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