JP2009235464A - Reduction treatment apparatus and reduction treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction treatment apparatus which can prevent the decrease of the total zinc amount in zinc refinement, and to provide a reduction treatment method therefor. <P>SOLUTION: The reduction treatment apparatus 1 includes: a rotary kiln 2 which heats a zinc-containing iron oxide and a reducing material to reduce the zinc-containing iron oxide and discharges an exhaust gas containing a zinc concentrate; and an exhaust-gas treatment device 3 which subjects the exhaust gas discharged from the rotary kiln 2 to predetermined treatment. The rotary kiln 2 and the exhaust-gas treatment device 3 have water-spraying portions 2g, 4a and 6a serving as a spraying portion for spraying an aqueous solution of sodium hydroxide, and a waste-liquid-injecting portion 4b provided thereon. These spraying portions spray a predetermined amount of the aqueous solution of sodium hydroxide therethrough toward the exhaust gas containing the zinc concentrate. Thereby, the obtained zinc concentrate contains a high concentration of zinc oxide and a reduced amount of chlorine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reduction treatment apparatus and a reduction treatment method for recovering zinc oxide at a high concentration from a zinc-containing raw material.

  Conventionally, in a reduction treatment apparatus, for example, ironworks generated dust containing zinc-containing iron oxide is treated, and the treated material is mixed with a reducing material that reduces zinc oxide, iron oxide, etc. in the treated material. A method for treating zinc-containing iron oxide is known in which the mixed material is charged into a rotary kiln furnace in a reducing atmosphere to reduce and evaporate zinc oxide with a reducing material and obtain an iron-containing material.

By such a treatment method, the iron-containing material from which zinc and the like are separated is recovered and zinc is recovered together with dust. Since this recovered zinc contains a relatively high concentration of zinc chloride (ZnCl ₂ ) due to chlorine (Cl) contained in the material to be treated and in the reduction furnace, the chlorine content that hinders zinc refining can be removed before refining. Need to be removed. Therefore, the zinc refining is performed on the recovered zinc after performing a dechlorination treatment as shown in Patent Document 1 as a pretreatment for the zinc refining.
JP 2000-128530 A

  Here, in the thing of the said patent document 1, the zinc chloride etc. which comprise some zinc collect | recovered with the reduction processing apparatus in a water treatment process, such as the water washing accompanying the dechlorination process which is pre-processing, are processed. There existed a problem that it melt | dissolved in water and a part of zinc could not be re-recovered after pre-processing, but the zinc total amount reduced.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a reduction treatment apparatus and a reduction treatment method capable of preventing reduction of the total amount of zinc for zinc refining.

  The reduction treatment apparatus according to the present invention reduces the zinc-containing raw material by heat-treating the zinc-containing raw material and the reducing material and discharges exhaust gas containing zinc concentrate, and the exhaust gas discharged from the reduction furnace. It is a reduction processing apparatus provided with the exhaust gas processing apparatus which performs a predetermined process. In this reduction treatment apparatus, at least one of the reduction furnace and the exhaust gas treatment apparatus is provided with a spray unit for spraying an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal to an exhaust gas containing a zinc concentrate. It is a feature.

  Further, the reduction treatment method according to the present invention includes a reduction furnace that heats a zinc-containing raw material and a reducing material to reduce the zinc-containing raw material to discharge an exhaust gas containing zinc concentrate, and an exhaust gas discharged from the reduction furnace. It is a reduction treatment method in a reduction treatment apparatus provided with an exhaust gas treatment apparatus that performs a predetermined treatment. This reduction treatment method is characterized by spraying an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal onto an exhaust gas containing a zinc concentrate in at least one of a reduction furnace and an exhaust gas treatment device.

  According to such a reduction treatment apparatus and reduction treatment method, at least one of the reduction furnace and the exhaust gas treatment apparatus sprays an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal on an exhaust gas containing a zinc concentrate. It has come to be. Thereby, before zinc existing in the reduction treatment apparatus is combined with chlorine and becomes zinc chloride, sodium hydroxide (NaOH) and chlorine are combined to form sodium chloride (NaCl). (ZnO). In addition, even when zinc present in the reduction treatment device becomes zinc chloride, a hydroxide such as sodium hydroxide and a zinc chloride cause a chemical reaction, and are replaced with a salt such as sodium chloride and zinc oxide. As the zinc chloride concentration in the zinc is reduced, the zinc oxide concentration is increased.

  In this way, by obtaining zinc containing high-concentration zinc oxide with reduced chlorine content, the dechlorination process itself, which is a pretreatment for zinc refining, is eliminated, and the total amount of zinc can be reduced by washing with water. In addition, the processing cost and processing time required for the preprocessing can be eliminated. Even when dechlorination is performed, the treatment time of water washing can be shortened by reducing zinc chloride, the amount of zinc dissolved in water by water washing is reduced, and the total amount of zinc by water washing is reduced. Reduction can be prevented. Furthermore, since zinc oxide is harder to be dissolved in treated water such as water than zinc chloride, by obtaining zinc containing a high concentration of zinc oxide, even when washing with dechlorinated water is performed, Reduction of the total amount of zinc by washing with water can be further prevented.

  The exhaust gas treatment device preferably includes at least one of a secondary combustion chamber for secondary combustion of the exhaust gas and a cooling device for introducing and cooling the exhaust gas. Thereby, the unburned part of the exhaust gas discharged from the reduction furnace can be completely burned, or the exhaust gas can be cooled and zinc can be easily recovered together with dust.

  Further, at least one of the reduction furnace, the secondary combustion chamber, and the cooling device is provided with a water spray portion that sprays cooling water, and the water spray portion also serves as a spray portion that sprays an aqueous solution of hydroxide. Preferably it is. Usually, the reduction furnace and the secondary combustion chamber are provided with a cooling water spray section for adjusting the combustion temperature, and the cooling device is provided with a cooling water spray section for cooling the exhaust gas. Zinc containing a high concentration of zinc oxide without causing an increase in processing costs such as providing a separate spraying part by spraying the aqueous solution of hydroxide using these water spraying parts Can be obtained.

  In addition, the reduction processing apparatus preferably includes a waste liquid injection unit for waste liquid combustion in the secondary combustion chamber, and the waste liquid injection unit also serves as a spray unit that sprays an aqueous solution of hydroxide. Some secondary combustion chambers are equipped with a waste liquid injection part for burning waste liquid. By using this waste liquid injection part to spray an aqueous solution of hydroxide, a separate spray part is provided. Zinc containing a high concentration of zinc oxide can be obtained without incurring an increase in the processing cost such as providing.

  Moreover, it is preferable that the spraying part which sprays aqueous solution is provided in at least one of a reduction furnace and a secondary combustion chamber. In the reduction furnace and the secondary combustion chamber, zinc is immediately after being reduced by the reducing material, and the ratio of zinc alone is high, and it is easily bonded to zinc oxide by hydroxides. Thus, zinc containing a high concentration of zinc oxide can be obtained efficiently without using too much energy.

  Thus, according to the present invention, it is possible to prevent a reduction in the total amount of zinc for zinc refining.

  Hereinafter, preferred embodiments of a reduction processing apparatus and a reduction processing method according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating a reduction treatment apparatus according to an embodiment of the present invention, and here, the reduction treatment apparatus is a reduction treatment apparatus for zinc-containing iron oxide.

  As shown in FIG. 1, the reduction treatment apparatus 1 is a rotary kiln that reduces zinc-containing iron oxide by introducing and heat-treating zinc-containing iron oxide (zinc-containing raw material) that is dust generated from a steel mill and a reducing material. (Reduction furnace) 2 and an exhaust gas treatment device 3 for performing a predetermined treatment on the exhaust gas discharged from the rotary kiln 2.

  The rotary kiln 2 has a cylindrical rotating body 2b, and is disposed so as to be inclined downward from a front part (left side in the figure) on the inlet side toward a rear part (right side in the figure) on the outlet side. The rotary kiln 2 may be placed horizontally. In the rotary kiln 2, the front end portion of the rotary body portion 2b is closed by the front support portion 2c, and the rear end portion is inserted into a secondary combustion chamber 4 described later, and is rotatably supported. The front support portion 2c is provided with an introduction duct 2d for introducing zinc-containing iron oxide into the furnace and a fuel combustion device 2e for setting the inside of the furnace to a reduction temperature. The introduction duct 2d includes a reducing material in the furnace. Is provided with a reducing material supply device 2f.

  Such a front support portion 2c is provided with a water spray portion 2g that sprays cooling water for adjusting the furnace temperature. Cooling water is supplied to the water spray portion 2g, and an aqueous solution of sodium hydroxide (NaOH) is supplied instead of the cooling water depending on the selection of the valve 11. For this reason, sodium hydroxide aqueous solution can be sprayed in a furnace from 2g of water spraying parts. Thus, since the water spraying part 2g also serves as the spraying part of the sodium hydroxide aqueous solution, it does not cause an increase in processing cost such as separately providing the spraying part in the furnace.

  The exhaust gas treatment device 3 includes a secondary combustion chamber 4 that performs secondary combustion of exhaust gas, a boiler 5 that performs heat exchange using exhaust gas from the secondary combustion chamber 4, and a gas cooling tower (cooling device) that cools the exhaust gas from the boiler 5 ) 6, a cyclone 7 that separates the exhaust gas from the gas cooling tower 6 into a solid gas, a front bag filter 8a that collects dust in the exhaust gas from the cyclone 7, a subsequent bag filter 8b, and a treatment agent for the exhaust gas As an exhaust gas treatment agent supply device 9 for supplying slaked lime and activated carbon, a chimney 10 is connected to the exhaust gas treatment agent supply device 9 for releasing desalted and other purified gas into the atmosphere. .

  The secondary combustion chamber 4 is connected to the outlet 2a of the rotary kiln 2 and performs secondary combustion of the exhaust gas from the rotary kiln 2 to complete the combustion. A water spray part 4 a for spraying cooling water for adjusting the room temperature is provided in the upper side wall of the secondary combustion chamber 4. Like the rotary kiln 2, the water spray part 4 a has a cooling function. Water is supplied, and an aqueous sodium hydroxide solution is supplied instead of cooling water depending on the selection of the valve 11. For this reason, sodium hydroxide aqueous solution can be sprayed indoors from the water spraying part 4a. Thus, since the water spraying part 4a also serves as the spraying part for the aqueous solution, there is no increase in processing costs such as providing a spraying part in the room separately.

  Further, a waste liquid injection part 4b for burning the waste liquid in the secondary combustion chamber 4 is provided in a side wall below the secondary combustion chamber 4, and the waste liquid is supplied to the waste liquid injection part 4b. Depending on the selection of the valve 12, a sodium hydroxide aqueous solution is supplied instead of the waste liquid. For this reason, the aqueous solution of sodium hydroxide can be sprayed upward from the waste liquid injection part 4b. As described above, since the waste liquid injection unit 4b also serves as the spray unit for the aqueous solution, there is no increase in processing cost such as separately providing the spray unit in the room. An opening 4c for discharging the iron-containing material reduced by the rotary kiln 2 is formed at the bottom of the secondary combustion chamber.

  The gas cooling tower 6 cools the exhaust gas from the boiler 5, and has a water spray section 6 a for spraying water for cooling, and this water as in the rotary kiln 2 and the secondary combustion chamber 4. Cooling water is supplied to the spray unit 6a, and an aqueous sodium hydroxide solution is supplied instead of the cooling water depending on the selection of the valve 11. For this reason, sodium hydroxide aqueous solution can be sprayed in a tower from the water spraying part 6a. Thus, since the water spraying part 6a also serves as the spraying part for the aqueous solution, there is no increase in processing costs such as providing a spraying part separately.

  In such a reduction treatment device 1, first, after the fuel combustion device 2e is driven in the rotary kiln 2 to make the inside of the furnace a reducing atmosphere, the zinc-containing iron oxide and the reducing material are supplied and mixed in the furnace, By heat-treating both, zinc-containing iron oxide is reduced with a reducing material to evaporate the zinc concentrate, and at the same time, the iron-containing material is separated. The separated iron-containing material flows down from the outlet 2a and is discharged to the outside through the opening 4c.

  Here, in the rotary kiln 2, a predetermined amount of a sodium hydroxide aqueous solution is sprayed from the water spray section 2g. For this reason, the sodium hydroxide aqueous solution spouted from the water spray portion 2g before the zinc concentrate containing a large amount of zinc (Zn) present immediately after the reduction is combined with chlorine to become zinc chloride Since chlorine is combined with sodium chloride, zinc is a zinc concentrate containing a large amount of zinc oxide (ZnO). A part of the zinc concentrate is combined with chloride in the furnace to become zinc chloride. In this way, the zinc concentrate with the increased concentration of zinc oxide volatilizes, scatters as fine particle dust, and is accompanied by the exhaust gas toward the secondary combustion chamber 4.

  In the secondary combustion chamber 4, unburned components in the exhaust gas are completely burned. Here, in the secondary combustion chamber 4, similar to the rotary kiln 2, a predetermined amount of sodium hydroxide aqueous solution is sprayed from the water spray section 4 a and the waste liquid injection section 4 b. For this reason, among zinc concentrates composed of zinc alone, zinc oxide, zinc chloride, etc., zinc chloride undergoes a chemical reaction with an aqueous solution of sodium hydroxide sprayed from the water spray part 4a and the waste liquid injection part 4b, and zinc oxide Thus, the zinc oxide concentration in the zinc concentrate is further increased and the zinc chloride concentration in the zinc concentrate is reduced. Such zinc concentrate is sent to the boiler 5 along with the exhaust gas. In addition, since the reduction process is not performed in the subsequent stage from the subsequent secondary combustion chamber 4, the ratio of zinc present as zinc oxide or zinc chloride is higher than that of zinc alone.

  Subsequently, the exhaust gas containing the zinc concentrate is sent to the boiler 5, and heat recovery is performed in the boiler 5 for effective use as a heat source. The exhaust gas containing the zinc concentrate that has passed through the boiler 5 is cooled to a predetermined temperature by the gas cooling tower 6.

  In the gas cooling tower 6, like the rotary kiln 2 and the secondary combustion chamber 4, a predetermined amount of aqueous sodium hydroxide solution is sprayed from the water spray section 6a. For this reason, among the zinc concentrates composed of zinc oxide, zinc chloride, etc., zinc chloride undergoes a chemical reaction by the aqueous sodium hydroxide solution sprayed from the water spraying part 6a and is replaced with zinc oxide. The zinc oxide concentration in the zinc concentrate is further increased and the zinc chloride concentration in the zinc concentrate is reduced. Such a zinc concentrate is accompanied by the exhaust gas and sent to the subsequent cyclone 7.

  The exhaust gas containing zinc concentrate sent to the cyclone 7 undergoes solid-gas separation in the cyclone 7 and is separated into zinc concentrate and exhaust gas, and the zinc concentrate is collected together with other dust. On the other hand, the exhaust gas that has passed through the cyclone 7 passes through the front-stage bag filter 8a. At this time, the zinc concentrate that has not been collected by the cyclone 7 is collected by the front-stage bag filter 8a. By such two-stage collection by the cyclone 7 and the pre-stage bag filter 8a, a zinc concentrate having a reduced chlorine content and containing a high concentration of zinc oxide can be obtained. The exhaust gas that has passed through the pre-stage bag filter 8a is subjected to a predetermined exhaust gas treatment by the exhaust gas treating agent supply device 9 or the like, and then released to the atmosphere through the chimney 10.

  As described above, according to the reduction treatment device 1 or the reduction treatment method using the reduction treatment device 1 according to the present embodiment, the sodium hydroxide aqueous solution is sprayed on the exhaust gas containing the zinc concentrate, so that the chlorine content is reduced. It is possible to obtain a zinc concentrate containing high-concentrated zinc oxide, eliminating the need for the dechlorination treatment itself, which is a pretreatment for zinc refining, and reliably preventing the reduction of the total amount of zinc by washing with water. it can. In addition, even when the dechlorination treatment is performed after this, the treatment time of the water washing can be shortened by reducing the zinc chloride, and the amount of zinc dissolved in the water by the water washing can be reduced. Reduction of the total amount of zinc can be prevented. Furthermore, since zinc oxide is harder to be dissolved in treated water such as water than zinc chloride, it is a case where washing with dechlorinated water is performed by obtaining a zinc concentrate containing high-concentration zinc oxide. Moreover, the reduction of the total amount of zinc by washing with water can be further prevented.

  Further, according to the reduction treatment device 1 or the reduction treatment method using the reduction treatment device 1 according to the present embodiment, at least the rotary kiln 2 and the secondary combustion chamber 4 are provided with spraying portions for spraying a sodium hydroxide aqueous solution. In the rotary kiln 2 and the secondary combustion chamber 4, zinc is immediately after being reduced by the reducing material and has a high ratio of zinc as a simple substance. Compared with the case where zinc chloride is replaced with zinc oxide, the amount of hydroxide is higher. Since chlorine is stabilized as sodium chloride with an aqueous sodium solution, it can be easily converted into zinc oxide. Thereby, the energy by the heat | fever at the time of combustion can be efficiently utilized for the chemical reaction of zinc, and the zinc concentrate containing a high concentration zinc oxide can be obtained.

  As described above, the present invention has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the water spray portions 2g, 4a, 6a and the waste liquid injection are provided. Although the part 4b is used as a spraying part for spraying the sodium hydroxide aqueous solution, a dedicated spraying part may be provided. Further, in the above embodiment, the aqueous solution of sodium hydroxide is sprayed from the four spraying portions, but if the aqueous solution of sodium hydroxide is sprayed from at least one of these spraying portions, the chlorine content is reduced. A zinc concentrate containing a high concentration of zinc oxide can be obtained by being reduced by a predetermined amount. In addition, a sensor unit that detects the amount of chlorine in the zinc concentrate is provided in the gas cooling tower 6 or the like at the subsequent stage, and spraying of an aqueous sodium hydroxide solution sprayed from each spray unit according to the amount of chlorine detected by the sensor unit. You may make it provide the control part which adjusts quantity.

  Moreover, in the said embodiment, although the aqueous solution of sodium hydroxide is used as the hydroxide sprayed from a spray part, it replaces with sodium hydroxide aqueous solution and is aqueous solution of hydroxides, such as potassium hydroxide and magnesium hydroxide. May be used. In short, an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal may be used. As reducing materials, ASR (automobile-derived shredder dust), home appliance shredder dust, waste plastic, RDF (Refuse Derived Fuel) obtained from waste, RPF (Refuse Paper and Plastic Fuel), sludge, oil mud, wood waste, fiber Waste, rubber waste, animal and vegetable residues, etc. may be used. In addition, when ASR, waste plastics, etc. are used as a reducing material, these contain a comparatively large amount of chlorine, but the high chlorine content is reduced by the above-described reduction treatment apparatus and reduction treatment method. A zinc concentrate containing a concentration of zinc oxide can be obtained. Moreover, in the said embodiment, although zinc containing iron oxide is introduce | transduced into the rotary kiln 2, what is introduce | transduced into the rotary kiln 2 is not limited to zinc containing iron oxide, What is necessary is just a zinc containing raw material.

It is a lineblock diagram showing the reduction processing device concerning the embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reduction processing apparatus, 2 ... Rotary kiln (reduction furnace), 2g, 4a, 6a ... Water spray part, 3 ... Exhaust gas processing apparatus, 4 ... Secondary combustion chamber, 4b ... Waste liquid injection | pouring part, 6 ... Gas cooling tower (cooling) apparatus).

Claims (6)

A reduction furnace for reducing the zinc-containing raw material by heat-treating the zinc-containing raw material and the reducing material and discharging exhaust gas containing zinc concentrate;
An exhaust gas treatment device that performs a predetermined treatment on the exhaust gas discharged from the reduction furnace;
A reduction processing apparatus comprising:
At least one of the reduction furnace and the exhaust gas treatment device is provided with a spray unit that sprays an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal on the exhaust gas containing the zinc concentrate. Reduction processing device to do.   2. The reduction processing apparatus according to claim 1, wherein the exhaust gas processing apparatus includes at least one of a secondary combustion chamber for secondary combustion of exhaust gas and a cooling device for introducing and cooling the exhaust gas. At least one of the reduction furnace, the secondary combustion chamber, and the cooling device includes a water spray unit that sprays cooling water,
The reduction treatment apparatus according to claim 2, wherein the water spray unit also serves as the spray unit that sprays the aqueous solution. The secondary combustion chamber includes a waste liquid injection unit for waste liquid combustion,
The reduction treatment apparatus according to claim 2, wherein the waste liquid injection unit also serves as the spray unit that sprays the aqueous solution.   The reduction treatment apparatus according to any one of claims 2 to 4, wherein the spray unit that sprays the aqueous solution is provided in at least one of the reduction furnace and the secondary combustion chamber. A reduction furnace that reduces the zinc-containing raw material by discharging the zinc-containing raw material and the reducing material to discharge exhaust gas containing zinc concentrate, and performs a predetermined treatment on the exhaust gas discharged from the reduction furnace A reduction treatment method in a reduction treatment device comprising an exhaust gas treatment device,
In at least one of the reduction furnace and the exhaust gas treatment device, a reduction treatment method characterized by spraying an aqueous solution of a hydroxide containing an alkali metal or an alkaline earth metal onto the exhaust gas containing the zinc concentrate.

Images