Reduction processing method, reduction processing apparatus

Abstract

To provide a reduction treatment method by which it is possible to decrease a concentration of a sulfur component in exhaust gas.SOLUTION: A reduction treatment method is intended to carry out reduction treatment of a material subjected to reduction by a rotary kiln. A scoop feeder is disposed in a midway of the rotary kiln. The method includes a reaction treatment agent addition step of loading a reductant and a desulfurization agent through the scoop feeder. The reductant is coal, and the desulfurization agent is quicklime.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reduction treatment method and a reduction treatment apparatus.

Background Art

[0002] For example, since ores are usually oxidized and contain a large amount of moisture, drying and reduction treatment have conventionally been performed on the ores before melting them in an electric furnace or the like (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When reducing a material to be reduced such as an ore, a carbon component such as coal is used as a reducing agent. However, since the inside of the furnace is usually in a reducing atmosphere, carbon is not sufficiently oxidized, and exhaust gas containing carbon monoxide may be generated. Although it is conceivable to use an oxidation catalyst to purify such exhaust gas, the exhaust gas usually contains a sulfur component due to raw materials such as ores. For this reason, when the exhaust gas containing a sulfur component is brought into contact with an oxidation catalyst, there are problems such as a decrease in the performance of the oxidation catalyst.

[0005] Therefore, in view of the problems of the above prior art, an object of one aspect of the present invention is to provide a reduction treatment method capable of reducing the concentration of a sulfur component in exhaust gas.

Means for Solving the Problems

[0006] According to one aspect of the present invention for solving the above problems, containing a sulfur component a reduction treatment method for reducing a material to be reduced in a rotary kiln, A reaction treatment agent addition step is provided in which a scoop feeder is provided in the middle of the rotary kiln, and a reducing agent and a desulfurizing agent are introduced through the scoop feeder. The reducing agent is coal and the desulfurizing agent is quicklime. and the material to be reduced is countercurrently heated by the combustion heat of the burner of the rotary kiln A reduction treatment method is provided.

Advantages of the Invention

[0007] According to one aspect of the present invention, a reduction treatment method capable of reducing the concentration of sulfur components in exhaust gas can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention. [Reduction Treatment Method] The reduction treatment method of the present embodiment is a reduction treatment method for reducing a material to be reduced in a rotary kiln, and may include a reaction treatment agent addition step in which a scoop feeder is provided in the middle of the rotary kiln, and a reducing agent and a desulfurizing agent are introduced through the scoop feeder.

[0010] The reducing agent may be coal, and the desulfurizing agent may be quicklime. (1) Regarding the material to be reduced The material to be reduced used in the reduction treatment method of this embodiment is not particularly limited. However, according to the reduction treatment method of this embodiment, since the concentration of sulfur components in the exhaust gas can be reduced, it is preferably a material to be reduced containing sulfur components.

[0011] Examples of the material to be reduced include various ores. In particular, ores of metals that require refining generally contain a large amount of moisture and are oxidized. And according to the reduction treatment method of this embodiment, since drying and reduction can be efficiently performed, 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.

[0012] The metal contained in the metal ore is not particularly limited. However, for example, it is preferably a metal containing non-ferrous metals, and more preferably an ore containing one or more metals selected from nickel, zinc, etc.

[0013] Note that the material to be reduced can also be pre-dried in advance to reduce and remove some of the adhering moisture. (2) Reaction treatment agent addition step The reduction treatment method of this embodiment can have a reaction treatment agent addition step as described above.

[0014] In the reaction treatment agent addition step, a scoop feeder is provided in the middle of the rotary kiln, and a reducing agent and a desulfurizing agent can be introduced through the scoop feeder. In the reaction treatment agent addition step, the reducing agent and the desulfurizing agent can be introduced and added to the material to be reduced heated in the rotary kiln as described above.

[0015] Since the reducing agent and the desulfurizing agent can also be added at different timings, the reaction treatment agent supply step can also have a reducing agent supply step for supplying the reducing agent and a desulfurizing agent supply step for supplying the desulfurizing agent.

[0016] After performing the reaction treatment agent addition step, the reduction treatment method of the present embodiment can heat while mixing the material to be reduced, a reducing agent, and a desulfurizing agent in a rotary kiln. At this time, the reduction treatment method of the present embodiment can perform a reduction drying step of reducing and drying the material to be reduced. Further, the reduction treatment method of the present embodiment can perform a desulfurization step of reducing and removing the sulfur component contained in the exhaust gas generated from the material to be reduced and the like during the reduction drying step by using a desulfurizing agent.

[0017] Hereinafter, a configuration example of a rotary kiln that can be used in the reduction treatment method of the present embodiment and a reaction treatment agent will be described. (2-1) Regarding the rotary kiln A configuration example of a rotary kiln that can preferably implement the reduction treatment method of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of the rotary kiln, and FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1.

[0018] The body portion 100 of the rotary kiln 10 shown in FIG. 1 has a substantially cylindrical shape, and the body portion 100 is configured to be rotatable about the central axis CA as a rotation axis. The rotary kiln 10 is provided so as to incline downward from the introduction end 101, which is one end in the longitudinal direction, toward the discharge end 102, which is the other end in the longitudinal direction. For this reason, the material to be reduced introduced from the introduction end 101 side moves to the discharge end side inside the rotating body portion 100. As will be 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 direction opposite to the moving direction of the material to be reduced, that is, from the discharge end 102 side to the introduction end 101 side, thereby heating the material to be reduced in countercurrent.

[0019] The rotary kiln 10 has a charging port 11 at the introduction end 101 which is one end in the longitudinal direction, and the material to be reduced can be charged into the interior of the body portion 100 through the charging port 11. Since the material to be reduced has already been described, the description is omitted here. Further, an exhaust pipe 12 is provided at the introduction end 101, and the exhaust gas generated in the rotary kiln can be exhausted from the exhaust pipe 12. The exhaust pipe 12 is preferably connected to, for example, a catalyst tower 30 described later so that carbon monoxide in the exhaust gas can be reduced and removed.

[0020] At the discharge end 102 which is the other end in the longitudinal direction of the rotary kiln 10, a discharge chute which is a discharge port 13 is provided so that the material to be reduced which has completed the reduction treatment inside the body portion 100 can be discharged. The material to be reduced which has completed the reduction treatment can be conveyed to an electric furnace or the like which performs other treatments as necessary. Further, a burner 14 is provided at the discharge end 102, and fossil fuel such as heavy oil is burned to heat the material to be reduced and the like charged into the interior of the body portion 100 of the rotary kiln 10. (Scoop feeder) The rotary kiln 10 can have a scoop feeder in the middle thereof, that is, between the introduction end 101 and the discharge end 102. Fig. 2 shows a cross-section of the position where the scoop feeder is provided, that is, a cross-sectional view taken along line A - A'.

[0021] As shown in Fig. 2, the rotary kiln 10 can have a rotating body portion 100 and an outer shell portion 110 covering the body portion 100. Note that the outer shell portion 110 does not need to be provided so as to cover the entire surface of the body portion 100, and for example, as shown in Fig. 1, it can also be provided only at necessary locations such as the location where the scoop feeder is provided.

[0022] The material to be reduced 21 charged from the charging port 11 is introduced into the body portion 100 and can move toward the discharge end 102 side as the body portion 100 rotates.

[0023] A space 120 is formed between the body part 100 and the outer shell part 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 on the outer shell part 110. A reaction treatment agent supply means 221 for supplying a reaction treatment agent as needed can be connected to the reaction treatment agent supply port 111.

[0024] The reaction treatment agent supply means 221 can have a reducing agent supply means for supplying a reducing agent and a desulfurizing agent supply means for supplying a desulfurizing agent, but for example, it may be a single reaction treatment agent supply means for supplying a reaction treatment agent in which a reducing agent and a desulfurizing agent are premixed in advance.

[0025] The configuration of the reaction treatment agent supply means 221 is not particularly limited, and the opening degree of the opening provided on the reaction treatment agent supply port 111 side can be configured to be adjustable according to the supply amount of the reaction treatment agent, so that the supply amount of the reaction treatment agent freely falling through the opening can be adjusted. Also, for example, it may have a conveying means such as a screw conveyor, and the conveying speed of the reaction treatment agent by the conveying means can be adjusted, and the supply amount of the reaction treatment agent can be adjusted according to the conveying speed.

[0026] The scoop feeder 130 can be formed of, for example, a tube having an L-shaped bend between a tip portion 131 and a straight portion 132. The scoop feeder 130 can rotate clockwise (right-handed) together with the body part 100, as indicated by the arrow in FIG. 2, for example. During such rotation, the reducing agent and the desulfurizing agent supplied to the space 120 at the tip portion 131 can be scooped up, and the scooped-up reducing agent and desulfurizing agent can be passed through the straight portion 132 and fed into the body part 100.

[0027] In the rotary kiln 10, the location where the scoop feeder is provided is not particularly limited, and it can be provided at an arbitrary location according to the temperature distribution inside the body part 100 of the rotary kiln 10 and the like.

[0028] For example, from the perspective of allowing a reduction reaction or a desulfurization reaction to proceed sufficiently, a scoop feeder can be provided at a location where the temperature inside the body portion 100 is 900°C or higher and 1200°C or lower. This is because by providing a scoop feeder at a location where the temperature inside the body portion 100 is 900°C or higher and 1200°C or lower and supplying a reaction treatment agent, the fixed carbon in the coal, which is a reducing agent contained in the reaction treatment agent, can be efficiently burned.

[0029] Note that the desulfurization reaction proceeds even at a relatively low temperature compared to the reduction reaction, for example, at 100°C or higher and 200°C or lower. Therefore, scoop feeders can also be provided at two locations along the longitudinal direction of the rotary kiln 10, for example. Specifically, a scoop feeder for adding a desulfurizing agent and a scoop feeder for adding a reducing agent can be provided respectively.

[0030] 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 on the introduction end 101 side of the outer shell portion 110 where the scoop feeder is provided is preferably 5% or more and 95% or less of the length L100 in the longitudinal direction of the body portion 100 of the rotary kiln 10, and more preferably 10% or more and 90% or less. (Regarding the operating conditions of the rotary kiln) The operating conditions of the rotary kiln are not particularly limited and can be arbitrarily selected according to the type of material to be reduced and the like.

[0031] 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 exhaust gas temperature in the furnace at the introduction end 101 can be set to 250°C or higher and 400°C or lower.

[0032] 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 temperature of the exhaust gas in the furnace at the introduction end 101 to 250 °C or higher, the fixed carbon in the supplied coal, which is the reducing agent, can be sufficiently burned, and the reduction treatment can be efficiently carried out. Further, 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 temperature of the exhaust gas in the furnace at the introduction end 101 to 400 °C or lower, the generation of beko can be suppressed, and the adhesion of beko to the furnace wall of the rotary kiln 10 can be suppressed.

[0033] The rotational speed of the rotary kiln 10, that is, the rotational speed of the body part 100 constituting the rotary kiln 10, is not particularly limited, but for example, it is preferably about 0.5 rpm or more and 1.5 rpm or less.

[0034] By setting the rotational speed of the rotary kiln 10 to 0.5 rpm or more, the stirring force in the rotary kiln 10 can be sufficiently increased, and the reaction can proceed sufficiently while exposing the reaction treatment agent such as the reducing agent introduced midway.

[0035] Further, by setting the rotational speed of the rotary kiln to 1.5 rpm or less, it is possible to prevent the material to be reduced or the like introduced into the rotary kiln 10 from rising in the rotary kiln 10 and being discharged as dust from the introduction end 101 together with the exhaust gas. (2-2) Regarding the reaction treatment agent In the reaction treatment agent supply step, as the reaction treatment agent, coal as a reducing agent and quicklime as a desulfurizing agent can be supplied. (Regarding the reducing agent) Coal can be preferably used as the reducing agent. The reducing agent may contain a reducing agent component other than coal or may be composed only of coal.

[0036] The reducing agent preferably has sufficient moisture removed, for example, the moisture content is preferably 2% by mass or more and 5% by mass or less. By removing the moisture in the reducing agent, after being supplied to the rotary kiln, the time required for moisture evaporation is suppressed, and the combustion of the fixed carbon contained in the reducing agent can be efficiently performed. (Regarding the desulfurizing agent) Quicklime, which is a desulfurizing agent, is considered to be able to react as shown in the following formulas (1) to (3) and desulfurize. In addition, in the reduction treatment method of this embodiment, since the drying of the material to be reduced is also performed, the atmosphere in the rotary kiln contains sufficient moisture, and the water in formula (1) is supplied from the atmosphere.

[0037] CaO + H2O → Ca(OH)2 ··· (1) SO2 + Ca(OH)2 → CaSO3·1 / 2H2O + 1 / 2H2O ··· (2) CaSO3·1 / 2H2O + 1 / 2O2 + 3 / 2H2O → CaSO4·2H2O ··· (3) In addition to quicklime, the desulfurizing agent can also contain slaked lime Ca(OH)2, etc., but from the viewpoint of enhancing the drying efficiency of the material to be reduced, it is preferably composed only of quicklime.

[0038] The reducing agent and the desulfurizing agent can be premixed to form a reaction treatment agent and then supplied into the rotary kiln 10, or they can be supplied into the rotary kiln 10 without mixing them.

[0039] The particle size of the reducing agent and the desulfurizing agent is not particularly limited. When supplied into the rotary kiln and the reaction treatment agent such as the reducing agent is mixed with the material to be reduced by the rotation of the rotary kiln, it is preferable to adjust the particle size so that the reaction treatment agent can be dispersed in the material to be reduced.

[0040] As described above, in the reaction treatment agent addition step, by adding the reaction treatment agent which is the reducing agent and the desulfurizing agent, the reduction of the material to be reduced and the reduction of the sulfur component in the exhaust gas can be performed together. (3) Exhaust gas treatment step The reduction treatment method of this embodiment can also include an exhaust gas treatment step of introducing the exhaust gas from the rotary kiln into a catalyst tower containing an oxidation catalyst to treat the exhaust gas.

[0041] In the exhaust gas treatment step, as shown in FIG. 1, the exhaust gas exhausted from the exhaust pipe 12 is introduced into the catalyst tower 30, and carbon monoxide in the exhaust gas can be reduced and removed.

[0042] As the oxidation catalyst, a known catalyst capable of reducing and removing carbon monoxide can be used, and it is not particularly limited.

[0043] In the reduction treatment method of this embodiment, as described above, the reaction treatment agent addition step is carried out, a desulfurizing agent is added to the material to be reduced, and drying and reduction are performed. Therefore, the content of sulfur components in the exhaust gas is reduced, and the oxidation catalyst can be prevented from being poisoned.

[0044] According to the reduction treatment method of this embodiment described above, in the reaction treatment agent addition step, since a desulfurizing agent is added to the material to be reduced, the sulfur components in the exhaust gas can be reduced. Therefore, when performing exhaust gas treatment to reduce carbon monoxide in the exhaust gas, the poisoning of the oxidation catalyst can be suppressed, and the exhaust gas treatment can be efficiently performed. [Reduction Treatment Apparatus] The reduction treatment apparatus of this embodiment is a reduction treatment apparatus for reducing the material to be reduced.

[0045] And the reduction treatment apparatus of this embodiment can include a rotary kiln, a scoop feeder disposed between both longitudinal ends of the rotary kiln, and a reaction treatment agent supply means for supplying a reducing agent and a desulfurizing agent provided in the scoop feeder. Note that the reducing agent is coal and the desulfurizing agent is quicklime.

[0046] According to the reduction treatment apparatus of this embodiment, the above-described reduction treatment method can be implemented. Therefore, the description of the matters already explained will be omitted.

[0047] The material to be reduced supplied to the reduction processing apparatus of the present embodiment is not particularly limited. However, according to the reduction processing apparatus of the present embodiment, since the concentration of sulfur components in the exhaust gas can be reduced, it is preferably a material to be reduced containing sulfur components.

[0048] Examples of the material to be reduced include various ores. In particular, ores of metals that require refining generally contain a large amount of moisture and are oxidized. And according to the reduction processing method of the present embodiment, since drying and reduction can be efficiently performed, 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.

[0049] The metal contained in the metal ore is not particularly limited. For example, it is preferably a metal containing a non-ferrous metal, and more preferably an ore containing one or more metals selected from nickel, zinc, etc.

[0050] Note that the material to be reduced can also be pre-dried in advance to reduce and remove some of the adhering moisture.

[0051] As described with reference to FIGS. 1 and 2, the reduction processing apparatus of the present embodiment can include a rotary kiln, a scoop feeder, and a reaction treatment agent supply means.

[0052] Since the rotary kiln and the scoop feeder have already been described, the description thereof is omitted here.

[0053] The reaction treatment agent supply means 221 only needs to be configured to be able to supply a reducing agent and a desulfurizing agent, which are reaction treatment agents, and the details thereof are not particularly limited.

[0054] The reaction treatment agent supply means 221 can also include a reducing agent supply means for supplying a reducing agent and a desulfurizing agent supply means for supplying a desulfurizing agent. However, for example, it may be one reaction treatment agent supply means for supplying a reaction treatment agent in which a reducing agent and a desulfurizing agent are mixed in advance.

[0055] The configuration of the reaction treatment agent supply means 221 is not particularly limited, and for example, it can have a storage container and a supply amount adjustment means.

[0056] The supply amount adjustment means can be configured to adjust, for example, the opening degree of the opening provided on the reaction treatment agent supply port 111 side of the storage container according to the supply amount of the reaction treatment agent, so that the supply amount of the reaction treatment agent freely falling through the opening can be adjusted. Further, the supply amount adjustment means can have, for example, a conveying means such as a screw conveyor, and can be configured to be able to adjust the conveying speed of the reaction treatment agent by the conveying means, and to adjust the supply amount of the reaction treatment agent according to the conveying speed.

[0057] In FIG. 1, an example in which the reaction treatment agent supply means 221 is provided at the reaction treatment agent supply port 111 is shown, but it is not limited to such a form. For example, the reaction treatment agent supply means 221 and the reaction treatment agent supply port 111 may be connected by a pipe, and the two members may be separated.

[0058] The reaction treatment agent supply means can also have a reducing agent supply means for supplying a reducing agent and a desulfurizing agent supply means for supplying a desulfurizing agent. By having the reducing agent supply means and the desulfurizing agent supply means, it becomes possible to control the supply amounts of the reducing agent and the desulfurizing agent respectively. Each supply means can have, for example, the configuration described for the reaction treatment agent supply means, and the reducing agent supply means and the desulfurizing agent supply means may have the same configuration or different configurations.

[0059] Since the reducing agent and the desulfurizing agent have already been described, the description is omitted here.

[0060] The reduction treatment apparatus of the present embodiment can also have a catalyst tower containing an oxidation catalyst for treating the exhaust gas from the rotary kiln.

[0061] As the oxidation catalyst, a known catalyst capable of reducing and removing carbon monoxide can be used, and it is not particularly limited.

[0062] As described above, the reduction processing apparatus of this embodiment adds a reaction processing agent, adds a desulfurizing agent to the material to be reduced, and performs drying and reduction. Therefore, the content of sulfur components in the exhaust gas is suppressed, and poisoning of the oxidation catalyst can be prevented.

[0063] According to the reduction processing apparatus of this embodiment described above, since the desulfurizing agent is added to the material to be reduced by the reaction processing agent adding means, the sulfur components in the exhaust gas can be reduced. Therefore, when performing exhaust gas treatment for reducing carbon monoxide in the exhaust gas, poisoning of the oxidation catalyst can be suppressed, and the exhaust gas treatment can be efficiently performed.

Explanation of Reference Numerals

[0064] 10 Rotary Kiln 130 Scoop Feeder 30 Catalyst Tower

Claims

Claim 1. A reduction treatment method for subjecting a material to be reduced containing a sulfur component to reduction treatment in a rotary kiln, comprising: a reaction treatment agent addition step of providing a scoop feeder in the middle of the rotary kiln and introducing a reducing agent and a desulfurizing agent through the scoop feeder; wherein the reducing agent is coal and the desulfurizing agent is quicklime; and wherein the material to be reduced is countercurrently heated by the combustion heat of a burner provided in the rotary kiln. Claim 2. The reduction treatment method according to claim 1, further comprising an exhaust gas treatment step of introducing the exhaust gas from the rotary kiln into a catalyst tower containing an oxidation catalyst to treat the exhaust gas. Claim 3. The reduction treatment method according to claim 1 or claim 2, wherein the material to be reduced contains a metal ore. Claim 4. A reduction treatment apparatus for subjecting a material to be reduced containing a sulfur component to reduction treatment, comprising: a rotary kiln; a scoop feeder disposed between both longitudinal ends of the rotary kiln; and reaction treatment agent supply means for supplying a reducing agent and a desulfurizing agent provided in the scoop feeder; wherein the reducing agent is coal and the desulfurizing agent is quicklime; and wherein the material to be reduced is countercurrently heated by the combustion heat of a burner provided in the rotary kiln. Claim 5. The reduction treatment apparatus according to claim 4, further comprising a catalyst tower containing an oxidation catalyst for treating the exhaust gas from the rotary kiln. Claim 6. The reduction treatment apparatus according to claim 4 or claim 5, wherein the material to be reduced contains a metal ore.

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