JP2009287051A - Zinc recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zinc recovery device which can efficiently recover zinc from zinc-containing ash. <P>SOLUTION: The zinc recovery device 5A by which zinc is recovered from zinc-containing flying ash, is provided with: a melting-reducing tank 19 storing flying ash, so as to be heated and vaporizing at least zinc among metals contained in the flying ash in a reducing atmosphere; and a splash condenser 23 and a zinc cooling unit 25 recovering the zinc vaporized in the melting-reducing tank 19. In the zinc recovery device 5A, since, of the metals contained in the flying ash, at least zinc is vaporized, and the vaporized zinc is recovered by the splash condenser 23 and the zinc cooling unit 25, the intrusion of impurities is reduced, and zinc is efficiently recovered in a state suitable for reutilization. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a zinc recovery device that recovers zinc from zinc-containing ash.

For example, a roasting device such as a rotary kiln described in Patent Document 1 may be used for processing steelmaking dust. This type of roasting device includes a roasting furnace for roasting dust in a reducing atmosphere, and a secondary combustion chamber for secondary combustion of combustion exhaust gas discharged from the roasting furnace. In a roasting furnace of a roasting apparatus, low-boiling metals such as zinc are vaporized and removed for recycling of iron and the like contained in dust. The vaporized zinc becomes fly ash (also referred to as “fly ash” or “FA”), passes through the secondary combustion chamber, and is captured and collected by a bag filter or the like.
JP 2005-29836 A

  When zinc is extracted from the collected fly ash and is to be recycled, if the collected fly ash does not have a zinc concentration of at least 50%, the processing burden associated with zinc collection is large and the zinc collection efficiency is poor. However, in the conventional roasting furnace, the concentration of zinc contained in the recovered fly ash is low, and in particular, since the device configuration is not intended for zinc recovery, zinc is efficiently recovered from zinc-containing ash. It was difficult.

  The object of the present invention is to provide a zinc recovery apparatus that can efficiently recover zinc from zinc-containing ash.

  The present invention relates to a zinc recovery apparatus for recovering zinc from zinc-containing ash, a heating chamber in which the ash is accommodated and heated, and at least zinc of the metal contained in the ash is vaporized in a reducing atmosphere, and a heating chamber And a recovery means for recovering the zinc vaporized in (1).

  In the present invention, at least zinc of the metal contained in the ash is vaporized, and the vaporized zinc is recovered by the recovery means, so that there is little contamination with impurities, and zinc can be efficiently recovered in a state suitable for reuse.

  Further, the zinc-containing ash is discharged from a roasting apparatus equipped with a roasting furnace for roasting zinc-containing materials, and the heating chamber contains the molten slag discharged from the roasting furnace, and the ash is removed by the molten slag. Heating is preferred. Since molten slag is discharged from the roasting furnace at a high temperature, the use of molten slag as a heat source for vaporizing zinc suppresses the consumption of new fuel to obtain the heat source, and recovers zinc efficiently. Is possible.

  Furthermore, the molten material discharged from the roasting furnace is further separated into molten metal and molten slag by a specific gravity difference, and further provided with a molten slag separation unit that supplies molten slag having a light specific gravity separated from the molten metal to the heating chamber. It is preferable. Since the molten metal and the molten slag are separated from the melt and only the molten slag is supplied to the heating chamber, the molten metal can be recovered and reused.

  Furthermore, it is preferable that the recovery means has a splash condenser that contains molten zinc and condenses the zinc vaporized in the heating chamber. By condensing and recovering vaporized zinc with a splash condenser, efficient recovery of zinc becomes possible.

  Further, it is preferable that the recovery means has a cooling means for cooling the zinc vaporized in the heating chamber to cause a phase transition from gas to solid. Since vaporized zinc can be solidified and recovered by a cooling means, zinc can be efficiently recovered as a solid.

  Further, the cooling means stores cooling water that contacts the gaseous zinc and causes the zinc to undergo a phase transition from gas to solid, and also includes a precipitation tank that precipitates and separates zinc in the cooling water, and cooling water drawn from the precipitation tank. It is preferable that the gaseous zinc is introduced into the ejector and stirred and mixed with the cooling water. Gaseous zinc is cooled by being in contact with cooling water efficiently while being stirred by the ejector. Therefore, the phase transition from gas to solid is efficiently performed, and further, precipitation is separated in the precipitation tank. As a result, it is possible to efficiently recover high-purity solid zinc.

  Furthermore, the zinc-containing ash is discharged from a roasting device equipped with a roasting furnace for roasting zinc-containing materials, and the heating chamber is formed by a housing portion for storing the ash and preheated air heated by the roasting device. It is preferable to have a heat exchanging part that heats the ash accommodated in the accommodating part. By using preheated air heated by a roasting device as a heat source for vaporizing zinc, consumption of new fuel for obtaining the heat source can be suppressed, and zinc can be recovered efficiently.

  Furthermore, it is preferable that the recovery means has a splash condenser that contains molten zinc and condenses the zinc vaporized in the heating chamber. By condensing and recovering vaporized zinc with a splash condenser, efficient recovery of zinc becomes possible.

  Further, it is preferable that the recovery means has a cooling means for cooling the zinc vaporized in the heating chamber to cause a phase transition from gas to solid. Since vaporized zinc can be solidified and recovered by a cooling means, zinc can be efficiently recovered as a solid.

  Further, the cooling means stores cooling water that contacts the gaseous zinc and causes the zinc to undergo a phase transition from gas to solid, and also includes a precipitation tank that precipitates and separates zinc in the cooling water, and cooling water drawn from the precipitation tank. It is preferable that the gaseous zinc is introduced into the ejector and stirred and mixed with the cooling water. Gaseous zinc is cooled by being in contact with cooling water efficiently while being stirred by the ejector. Therefore, the phase transition from gas to solid is efficiently performed, and further, precipitation is separated in the precipitation tank. As a result, it is possible to efficiently recover high-purity solid zinc.

  According to the present invention, zinc can be efficiently recovered from zinc-containing ash.

  Hereinafter, a preferred embodiment of a zinc recovery apparatus according to the present invention will be described with reference to the drawings. 1 is a diagram schematically showing a zinc recovery system according to the first embodiment, FIG. 2 is a cross-sectional view schematically showing a kiln rotary furnace according to the present embodiment, and FIG. 3 is taken along the line III-III in FIG. FIG. 4 is a diagram schematically showing a zinc recovery device according to this embodiment, and FIG. 5 is a diagram schematically showing a splash condenser according to this embodiment.

(First embodiment)
As shown in FIG. 1, the zinc recovery system 1A includes a kiln rotary furnace (roasting apparatus) 3A for roasting zinc-containing materials W1 such as steelmaking dust, and a zinc-containing fly discharged from the kiln rotary furnace 3A. And a zinc recovery device 5A for recovering zinc from ash (also referred to as “fly ash” or “FA”) Fa.

  The kiln rotary furnace 3A includes a vertical kiln, but a horizontal kiln is employed in this embodiment. As shown in FIG. 2, the kiln rotary furnace 3 </ b> A includes a cylindrical roasting furnace 7 that roasts the zinc-containing material W <b> 1 and a secondary combustion chamber that performs secondary combustion of combustion exhaust gas discharged from the roasting furnace 7. 9 and. The roasting furnace 7 and the secondary combustion chamber 9 are maintained in a reducing atmosphere, and the roasting furnace 7 is maintained at a furnace temperature of 1500 ° C. or higher, and secondary combustion of low-boiling point metals such as zinc and combustion exhaust gas is performed. Drain into chamber 9.

  A gear 7a is provided on the outer periphery of the roasting furnace 7, and the roasting furnace 7 is rotated around the axis L by a motor (not shown). The roasting furnace 7 is inclined downward from the receiving side Us toward the discharging side Ds so that the zinc-containing material W1 can be moved from the receiving side Us to the discharging side Ds. The roasting furnace 7 and the secondary combustion chamber 9 are joined so that the roasting furnace 7 can rotate and the airtightness of the joint is maintained.

  A front wall 7 b that is an end surface on the receiving side Us of the roasting furnace 7 is formed with a receiving port connected to the fixed amount supply device 8. Further, an auxiliary burner 7c is disposed through the front wall 7b. The auxiliary burner 7c radiates a flame from the front wall 7b toward the discharge side Ds of the roasting furnace 7. Fuel such as heavy oil is supplied to the auxiliary burner 7c from a fuel tank by a fuel pump (not shown).

  The fixed amount supply device 8 includes a cylinder part 8a connected to the receiving port of the front wall 7b, an extruding part 8b that reciprocates within the cylinder part 8a, a feeder 8c that drives and controls the reciprocating movement of the extruding part 8b, and a cylinder. And a hopper 8d communicating with the portion 8a. In addition to the zinc-containing material W1 such as steelmaking dust, the hopper 8d is charged with a reducing agent, activated carbon for dioxin adsorption, and the like. A predetermined amount of the zinc-containing material W1 deposited in the hopper 8d is supplied into the roasting furnace 7 by the reciprocating motion of the extrusion portion 8b. The fixed amount supply device 8 may be a device that supplies the zinc-containing material W1 and the like into the roasting furnace 7 by a screw conveyor or the like.

  The zinc-containing material W1 supplied into the roasting furnace 7 is heated by the auxiliary burner 7c from the beginning of supply. In the roasting furnace 7, the zinc-containing material W1 is heated to 1500 ° C. or higher while being stirred, and moves from the receiving side Us to the discharging side Ds. In the roasting furnace 7, molten metal W3 and molten slag W4 containing iron in the zinc-containing material W1 and other metals having a high boiling point are generated and discharged from the outlet of the discharge side Ds. In addition, the organic matter contained in the zinc-containing material W1 is thermally decomposed in the roasting furnace 7, becomes a gaseous combustible material, and is sent to the secondary combustion chamber 9 as combustion exhaust gas. Furthermore, in the roasting furnace 7, low-boiling point metals such as zinc evaporate and fly ash Fa together with the combustion exhaust gas is sent to the secondary combustion chamber 9.

  The secondary combustion chamber 9 is provided with an auxiliary burner (not shown) to completely burn the gaseous combustible component in the combustion exhaust gas. A melted slag separation unit 11 and a flying dust discharge unit 12 are provided adjacent to each other at the lower part of the secondary combustion chamber 9. The molten slag separation unit 11 is provided on the roasting furnace 7 side, and the flying dust discharge unit 12 is provided on the inclined side surface side of the secondary combustion chamber 9.

  The flying dust drops at a low flow velocity in the secondary combustion chamber 9 and is sent from the flying dust discharge unit 12 to the powder discharge means 16 such as a screw conveyor. The flying dust contains a large amount of unburned matter, and the flying dust transported by the powder discharging means 16 is put into the roasting furnace 7 again. On the other hand, the zinc-containing fly ash Fa discharged from above the secondary combustion chamber 9 is captured by the bag filter 17 and sent to the FA feeder 21 of the zinc recovery device 5A.

  The secondary combustion chamber 9 is provided with a preheated oxygen pipe 13 and a preheated air pipe 15 for preheating oxygen and air by heat exchange with the high temperature exhaust gas. The preheated oxygen pipe 13 is branched in three directions: a first transfer pipe 13a, a second transfer pipe 13b, and a third transfer pipe 13c. The first transfer pipe 13 a and the second transfer pipe 13 b are connected to the smelting reduction tank 19, and supply combustion oxygen and reducing oxygen to the smelting reduction tank 19. The third transfer pipe 13 c extends in the secondary combustion chamber 9 to above the molten slag separator 11. Further, the preheated air pipe 15 is connected to the smelting reduction tank 19 and functions as a heat exchanging section using preheated air as a heat source.

  The molten slag separation unit 11 overflows from the specific gravity separation hopper 11a disposed adjacent to the lower exit of the roasting furnace 7, the molten metal recovery unit 11b disposed below the specific gravity separation hopper 11a, and the specific gravity separation hopper 11a. And a molten slag supply line 11d for supplying the molten slag W4 stored in the slag holding tank 11c to the zinc recovery device 5A.

  The specific gravity separation hopper 11a has a tapered hole Th for receiving the melt W2. The taper hole Th is reduced in diameter so as to be wide at the upper side and narrow at the lower part as the bottom. An outlet is formed at the bottom of the tapered hole Th, and the specific gravity separation hopper 11a is provided with a gate valve 11f for opening and closing the outlet. Further, the specific gravity separation hopper 11a is provided with a groove (not shown) for overflowing the molten slag W4 from the upper portion of the tapered hole Th and feeding it into the slag holding tank 11c.

  The melt W2 discharged from the roasting furnace 7 contains a molten metal W3 such as iron and a molten slag W4 that can be reused as resources. Since the specific gravity of the molten metal W3 is heavier than that of the molten slag W4, the molten metal W3 separates from the molten slag W4 and precipitates due to this specific gravity difference. The molten slag W4 separated from the molten metal W3 overflows from the tapered hole Th and is fed into the slag holding tank 11c. Above the specific gravity separation hopper 11a, an ejection port of the third transfer pipe 13c of the preheating oxygen pipe 13 is arranged, and high temperature oxygen is blown toward the surplus reducing agent (carbon) floating on the surface layer. Used for reducing agent combustion treatment. In addition, since this reducing agent can be utilized as a reducing agent for the later-described smelting reduction tank 19, it is not necessary to perform the combustion treatment here.

  The gate valve 11f closes the outlet at the lower end of the tapered hole Th, and when the molten metal W3 accumulates to some extent, the outlet of the tapered hole Th is temporarily opened, and the molten metal W3 flows out and closes again. The molten metal W3 flows out from the outlet of the tapered hole Th and is sent to the molten metal recovery part 11b. In the molten metal recovery unit 11b, the molten metal W3 is solidified by cooling water and conveyed by a metal conveyor. Metals such as iron conveyed by metal conveyors are reused as resources.

  The molten slag supply line 11d is provided with a transfer pipe, an on-off valve, and the like, and connects the slag holding tank 11c and the smelting reduction tank 19 (see FIG. 4). When a predetermined amount or more of molten slag W4 accumulates in the slag holding tank 11c, the on-off valve is opened, and the molten slag W4 is supplied to the smelting reduction tank 19. In the present embodiment, the molten slag separator 11 is provided in the lower part of the secondary combustion chamber 9 constituting the kiln rotary furnace 3A, but is provided independently of the kiln rotary furnace 3A, and the roasting furnace 7 The aspect connected to 3 A of kiln rotary furnaces via the transfer pipe | tube of the melt W2 discharged | emitted from A may be sufficient. The molten slag separation unit 11 constitutes a part of the zinc recovery device 5A.

  The zinc recovery device 5 </ b> A receives a molten slag W <b> 4 supplied from the molten slag separation unit 11 and receives and stores the molten slag W <b> 4 and the fly ash Fa captured by the bag filter 17 and receives the molten slag W <b> 4. FA supply device 21 for supplying to the battery, a splash condenser 23 for condensing zinc vaporized in the smelting reduction tank 19, and a zinc cooling unit (cooling means) 24 for solidifying the remaining zinc discharged from the splash condenser 23. ing. In the present embodiment, the splash condenser 23 and the zinc cooling unit 24 correspond to the recovery means.

  The smelting reduction tank 19 has a first chamber 19a and a second chamber 19b adjacent to the left and right. The first room 19a and the second room 19b are partitioned by a partition wall 19c with the upper part being in communication with the lower part. The ceiling of the first room 19a is open, and the ceiling of the second room 19b is closed. A downstream end of the molten slag supply line 11d is disposed above the first chamber 19a. The molten slag W4 passes through the molten slag supply line 11d and is supplied to the first chamber 19a as a heat source for the smelting reduction tank 19. The first chamber 19a and the second chamber 19b communicate with each other through a gap below the partition wall 19c, and the molten slag W4 flows into the second chamber 19b through the gap. The gas phase portion Ga, which is the upper region in the second chamber 19b, is in a state of being blocked from the outside.

  The fly ash supply pipe 21a of the FA supplier 21 is connected to the ceiling of the second room 19b. The FA feeder 21 further includes a hopper 21b into which the fly ash Fa is charged and a screw conveyor 21c connected to the lower end of the hopper 21b. The fly ash Fa charged into the hopper 21b is transferred to the fly ash supply pipe 21a by the screw conveyor 21c, and supplied to the second chamber 19b through the fly ash supply pipe 21a. In the second chamber 19b, molten slag W4 having a high temperature of 1200 ° C. or higher is accommodated as a heat source, and a reducing atmosphere is formed. By supplying the fly ash Fa to the second chamber 19b, the zinc contained in the fly ash Fa is vaporized. The vaporized zinc is discharged together with the exhaust gas from a zinc discharge part 19d provided in the second chamber 19b. For the formation of the reducing atmosphere in the smelting reduction tank 19, an excessive reducing agent brought from the kiln rotary furnace 3A together with the molten slag W4, activated carbon in the fly ash Fa used for dioxin adsorption, and the like are effectively used. The

  The second chamber 19b is supplied with auxiliary burner 19f for auxiliary heating and oxygen preheated in the secondary combustion chamber 9 of the kiln rotary furnace 3A in the chamber for promoting combustion of the auxiliary burner 19f. A preheated oxygen supply unit 19g is provided. The preheated oxygen supply unit 19 g is connected to the preheated oxygen pipe 13. Further, a preheated air pipe 15 is laid in the second chamber 19b, and functions as a heat exchanging unit that uses the preheated air heated in the secondary combustion chamber 9 as a heat source.

  The state of each metal in the smelting reduction tank 19 will be described with reference to FIG. FIG. 6 is a diagram showing the melting point, boiling point and equilibrium vapor pressure of each metal. Zinc (Zn) has a boiling point of 100 ° C. or less, volatilizes in the roasting furnace 7, is captured as fly ash Fa by the bag filter 17, and is supplied to the second chamber 19 b of the smelting reduction tank 19.

  The temperature in the smelting reduction tank 19 needs to be a temperature at which at least zinc can be vaporized and supplied to the subsequent splash condenser 23 together with the exhaust gas. For that purpose, the temperature in the smelting reduction tank 19 is set to 1200 ° C. to 1300 ° C. It is preferable to maintain the temperature at about ° C. By using the molten slag W4 as a heat source, it is possible to maintain this temperature state. By setting the temperature of the smelting reduction tank 19 to 1200 ° C. to 1300 ° C., the zinc in the fly ash Fa supplied to the smelting reduction tank 19 is smelted and reduced to be vaporized and introduced into the splash condenser 23 together with the exhaust gas. On the other hand, the residue in the fly ash Fa is discharged from the slag discharge part 19h together with the molten slag W4.

  The splash condenser 23 is provided adjacent to the smelting reduction tank 19. As shown in FIG. 5, the splash condenser 23 includes a storage tank 23a that stores molten zinc, and an introduction portion 23b that introduces gaseous zinc into the storage tank 23a. The introduction part 23b is connected to a zinc discharge part 19d of the smelting reduction tank 19 via a zinc transfer pipe 23c (see FIG. 4), and the zinc vaporized in the smelting reduction tank 19 passes through the zinc transfer pipe 23c and the introduction part 23b. It passes through and is supplied to the storage tank 23a.

  The splash condenser 23 includes a plurality of stirring blades 23d that stir and scatter molten zinc stored in the storage tank 23a. Gaseous zinc is efficiently condensed by coming into contact with the scattered zinc. The zinc condensed in the storage tank 23a is withdrawn from the recovery pipe 23f and recovered as crude zinc Z1. Zinc that has not been condensed in the storage tank 23a is discharged from the discharge portion 23g together with the exhaust gas.

  As shown in FIGS. 1 and 2, the zinc cooling unit 24 is provided adjacent to the splash condenser 23. The zinc cooling unit 24 includes a settling tank 25 that stores makeup water (cooling water) W for cooling and washing zinc in the exhaust gas. The settling tank 25 is connected with a makeup water W introduction pipe 25a and a discharge pipe 25b. Furthermore, the zinc cooling unit 24 includes a circulation line 26 for makeup water W connected to a precipitation tank 25. The circulation line 26 includes an ejector 26 a that injects makeup water W into the precipitation tank 25, a makeup water transfer pipe 26 b that communicates the ejector 26 a and the lower part of the precipitation tank 25, and makeup water W in the precipitation tank 25. And a pump 26c that draws out and feeds the ejector 26a to the ejector 26a with a predetermined pressure. The ejector 26a is connected to the discharge part 23g of the splash condenser 23 via the duct pipe 26d.

  Gaseous zinc reaches the ejector 26a through the duct pipe 26d, is cooled in contact with the makeup water W efficiently while being stirred by the ejector 26a, and is injected into the sedimentation tank 25 together with the makeup water W. . The zinc cooled by the makeup water W undergoes a phase transition from a gas to a solid, that is, solidifies and precipitates in the precipitation tank 25. A discharge port 25c for zinc Z2 is provided at the bottom of the precipitation tank 25. Since the zinc Z2 recovered by the zinc cooling unit 24 has a high purity and a small post-treatment burden, it can be reused efficiently. In particular, since chlorine is removed by the makeup water W, it can be recovered as high-quality zinc Z2.

  Next, a zinc recovery method using the zinc recovery device 5A will be described. In the roasting furnace 7 of the kiln rotary furnace 3 </ b> A, the temperature in the furnace is maintained at about 1500 ° C. or higher to roast the zinc-containing material W <b> 1, and the zinc-containing combustion exhaust gas is discharged into the secondary combustion chamber 9. In the secondary combustion chamber 9, combustible substances in the combustion exhaust gas are subjected to secondary combustion, the remaining fly ash Fa containing zinc is discharged from the secondary combustion chamber 9, and the fly ash Fa is captured by the bag filter 17.

  On the other hand, the roasting furnace 7 discharges the melt W2 containing a metal having a relatively high boiling point such as iron to the molten slag separation unit 11, and the molten slag separation unit 11 causes the molten metal W3 and the molten slag W4 to differ due to the specific gravity difference. And the molten metal W3 is withdrawn and recovered for reuse. The molten slag W4 is supplied to the smelting reduction tank 19 as a heat source for the smelting reduction tank 19.

  The zinc-containing fly ash Fa captured by the bag filter 17 is supplied to the smelting reduction tank 19. The smelting reduction tank 19 is maintained at about 1200 ° C. to 300 ° C. by the molten slag W4, and vaporizes zinc in the fly ash Fa in the smelting reduction tank 19 (vaporization step). In addition, when temperature becomes unstable only by molten slag W4, the smelting reduction tank 19 is hold | maintained at about 1200-1300 degreeC by heat exchange using the auxiliary burner 19f or preheating air. Further, the smelting reduction tank 19 is maintained in a reducing atmosphere, and zinc in the fly ash Fa is melted and reduced, and then vaporized and supplied to the splash condenser 23.

  In the splash condenser 23, the vaporized zinc is condensed and recovered as crude zinc Z1. Further, the zinc that could not be condensed in the splash condenser 23 is supplied to the zinc cooling unit 24 together with the exhaust gas, cooled, and precipitated and separated in the precipitation tank 25 of the zinc cooling unit 24 to be recovered as high-purity zinc Z2 ( Recovery process).

  According to the above zinc recovery apparatus 5A, at least zinc is vaporized among the metals contained in the fly ash Fa discharged from the secondary combustion chamber 9 of the kiln rotary furnace 3A, and the vaporized zinc is splashed into the splash condenser 23 or the zinc cooling. Since it is recovered by the unit 24, there is little mixing of impurities, and zinc can be efficiently recovered in a state suitable for reuse. Usually, a zinc refining manufacturer or the like does not purchase a raw material unless the zinc concentration is at least 50%. Therefore, if the fly ash Fa is to be processed, it is necessary to have an outside contractor or the like process it for a fee. However, in this embodiment, since zinc Z1 and Z2 can be efficiently recovered from the fly ash Fa, it becomes possible to recover zinc having a high concentration of 80% or more, and it can be sold as a zinc raw material to a zinc refining manufacturer. There are also significant economic advantages in terms of cost.

  Furthermore, since zinc is vaporized by using the molten slag W4 discharged from the roasting furnace 7 in a high temperature state as a heat source, consumption of new fuel for obtaining the heat source is suppressed, and zinc can be recovered efficiently. It becomes possible. In particular, in the present embodiment, the melt W2 discharged from the roasting furnace 7 is separated into the molten metal W3 and the molten slag W4 by the molten slag separation unit 11, and only the molten slag W4 is supplied to the reduction melting tank. The molten metal W3 can be recovered and reused.

  Further, in the present embodiment, the splash condenser 23 is arranged on the upstream side where the vaporized zinc flows, and the zinc cooling unit 24 is arranged on the downstream side, so that the vaporized zinc is condensed and collected by the splash condenser 23, Since the remaining zinc that could not be condensed by the splash condenser 23 is solidified and recovered by the zinc cooling unit 24, the evaporated zinc can be recovered efficiently without escaping.

  Further, in the zinc cooling unit 24, gaseous zinc is cooled and solidified by makeup water (cooling water) W, and the chlorine content is washed and removed by the makeup water W. In recent years, waste plastics are often used as an alternative fuel from the viewpoint of saving fossil fuels and effectively using waste in steelmaking processes, etc., and the chlorine content in fly ash Fa recovered by the bag filter tends to increase. It is in. If the chlorine content is high, there will be a problem of chlorination at the zinc refining manufacturer, and the zinc raw material will be of low quality. In the present embodiment, by providing the zinc cooling unit 24, the chlorine content is washed and removed by the makeup water W, so that high-quality zinc Z2 can be recovered.

  Moreover, since the zinc-containing exhaust gas discharged from the splash condenser 23 is introduced into the ejector 26a, the gaseous zinc is cooled in contact with the makeup water W efficiently while being stirred by the ejector 26a. As a result, the phase transition from the gas to the solid is efficiently performed, and further, the precipitate is separated in the precipitation tank 25, so that the solid zinc Z2 having a high purity can be efficiently recovered.

(Second Embodiment)
Next, a zinc recovery system according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram schematically showing a zinc recovery system according to the second embodiment. Note that in the second embodiment, elements substantially similar to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the zinc recovery system 1B includes a kiln rotary furnace 3A including a roasting furnace 7 and a secondary combustion chamber 9, and a zinc recovery device 5B. The zinc recovery device 5B includes a molten slag separation unit 11 provided in the lower part of the secondary combustion chamber 9, a smelting reduction tank 19 that stores the molten slag W4 supplied from the molten slag separation unit 11 as a heat source, and a smelting reduction tank. 19 includes an FA feeder 21 for supplying zinc-containing fly ash Fa, and a splash condenser 23 for condensing and recovering zinc vaporized in the smelting reduction tank 19 as crude zinc Z1.

  In the present embodiment, unlike the first embodiment, there is no zinc cooling unit for solidifying and recovering the remaining zinc discharged from the splash condenser 23. Instead, the exhaust gas from the splash condenser 23 is not recovered. An exhaust gas return line 27 for returning to the next combustion chamber 9 is provided.

  Also in the zinc recovery apparatus 5B according to the present embodiment, at least zinc is vaporized and vaporized among the metals contained in the fly ash Fa discharged from the secondary combustion chamber 9 of the kiln rotary furnace 3A, as in the first embodiment. Since the collected zinc is recovered by the splash condenser 23, there is little mixing of impurities, and zinc can be efficiently recovered in a state suitable for reuse.

(Third embodiment)
Next, a zinc recovery system according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a diagram schematically showing a zinc recovery system according to the third embodiment. FIG. 9 is a cross-sectional view schematically showing the kiln rotary furnace according to this embodiment, and FIG. 10 is a view schematically showing the zinc recovery apparatus according to this embodiment. Note that in the third embodiment, elements that are substantially similar to those in the first embodiment are denoted by the same reference numerals, and a detailed description thereof is omitted.

  As shown in FIG. 8, the zinc recovery system 1C includes a kiln rotary furnace 3B and a zinc recovery device 5C. As shown in FIG. 9, the kiln rotary furnace 3B includes a cylindrical roasting furnace 29 that roasts the zinc-containing material W1, and a secondary combustion chamber 31 that performs secondary combustion of combustion exhaust gas discharged from the roasting furnace. And. The roasting furnace 29 and the secondary combustion chamber 31 are maintained in a reducing atmosphere. In the roasting furnace, the furnace temperature is maintained at about 1500 ° C. or higher, and a low-boiling point metal such as zinc is combusted together with the combustion exhaust gas. Discharge into chamber 31.

  Unlike the first embodiment, the molten slag separation part is not provided in the lower part of the secondary combustion chamber 31. The molten material W2 including the molten metal W3 discharged from the roasting furnace 29 is cooled by the molten metal recovery unit 11b and then conveyed and recovered by a metal conveyor. Further, the flying dust dropped in the secondary combustion chamber 31 is returned to the roasting furnace 29 and burned again.

  The secondary combustion chamber 31 is provided with a preheated oxygen pipe 33 and a preheated air pipe 35 for preheating oxygen and air by heat exchange with the high temperature exhaust gas. The preheating oxygen pipe 33 is connected to the solid reduction tank 37 in order to supply combustion oxygen and reduction oxygen to the solid reduction tank 37. The preheating air pipe 35 is connected to the molten solid reduction tank 37 and functions as a heat exchanging unit using preheating air as a heat source as a heat source.

  As shown in FIGS. 8 and 10, the zinc recovery device 5 </ b> C includes a solid reduction tank (heating chamber) 37 that heats zinc-containing fly ash Fa in a reducing atmosphere, and fly ash captured by the bag filter 17. FA supplier 21 that supplies Fa to the solid reduction tank 37, a splash condenser 23 that condenses the zinc vaporized in the solid reduction tank 37, and zinc that cools and solidifies the remaining zinc that has not been condensed in the splash condenser 23 And a cooling unit 24.

  The solid reduction tank 37 includes a fly ash storage chamber (storage unit) 37a that stores fly ash Fa. A conveyor 37g for circulating a plurality of trays 37b is installed in the fly ash storage chamber 37a. One end side of the fly ash storage chamber 37a is an upstream position Up of the tray 37b, and the other end side is a downstream position Dp of the tray. The plurality of trays 37b move in the forward direction from the upstream position Up to the downstream position Dp and turned upside down, and then move in the reverse direction from the downstream position Dp to the upstream position Up to return to the original state again at the upstream position Up. . The fly ash supply pipe 21a of the FA feeder 21 is provided so that the fly ash Fa can be supplied to the tray 37b at the upstream position Up, and the dust discharge portion 37c is formed from the tray 37b turned upside down at the downstream position Dp. It is provided at a position where it can receive and discharge the fallen dust.

  A preheated air pipe 35 through which preheated air heated in the secondary combustion chamber 31 of the kiln rotary furnace 3B passes is laid in the fly ash storage chamber 37a. The preheated air pipe 35 functions as a heat exchanging part and uses preheated air as a heat source for vaporizing zinc in the fly ash Fa. The fly ash storage chamber 37a is further provided with an auxiliary burner 37d for vaporizing zinc in the fly ash Fa. The fly ash storage chamber 37a is maintained at 1200 ° C. to 1300 ° C. by the preheated air pipe 35 and the auxiliary burner 37d.

  The splash condenser 23 is provided adjacent to the solid reduction tank 37. The introduction part 23b of the splash condenser 23 is connected to the zinc discharge part 37f of the solid reduction tank 37 via the zinc transfer pipe 23c, and the zinc vaporized in the solid reduction tank 37 is passed through the zinc transfer pipe 23c and the introduction part 23b. It passes through and is supplied to the storage tank 23a. In the storage tank 23a, molten zinc is stirred and scattered by the stirring blade 23d, and the gaseous zinc is efficiently condensed by coming into contact with the scattered zinc. The zinc stored in the storage tank 23a is withdrawn from the recovery pipe and recovered as crude zinc Z1. Zinc that has not been condensed in the storage tank 23a is discharged from the discharge portion 23g together with the exhaust gas.

  The zinc cooling unit 24 is provided adjacent to the splash condenser 23. The zinc cooling unit 24 includes a settling tank 25 that stores makeup water (cooling water) W for cooling and washing zinc in the exhaust gas. The settling tank 25 is connected with a makeup water W introduction pipe 25a and a discharge pipe 25b. Furthermore, the zinc cooling unit 24 includes a circulation line 26 for makeup water W connected to a precipitation tank 25. The circulation line 26 includes an ejector 26 a that injects makeup water W into the precipitation tank 25, a makeup water transfer pipe 26 b that communicates the ejector 26 a and the lower part of the precipitation tank 25, and makeup water W in the precipitation tank 25. And a pump 26c that draws out and feeds the ejector 26a to the ejector 26a with a predetermined pressure. The ejector 26a is connected to the discharge part 23g of the splash condenser 23 via the duct pipe 26d.

  The gaseous zinc reaches the ejector 26a through the duct pipe 26d, is cooled in contact with the makeup water W efficiently while being stirred by the ejector 26a, and is injected into the zinc precipitation tank 25 together with the makeup water W. The The zinc cooled by the makeup water W undergoes a phase transition from a gas to a solid, that is, solidifies and precipitates in the zinc precipitation tank 25. A discharge port 25c for zinc Z2 is provided at the bottom of the zinc precipitation tank 25. Zinc Z2 recovered in the zinc precipitation tank 25 has a high purity and a small post-treatment burden, so that it can be reused efficiently.

  Next, a zinc recovery method using the zinc recovery device 5C will be described. In the roasting furnace 29 of the kiln rotary furnace 3B, the temperature in the furnace is maintained at about 1500 ° C. or more to roast the zinc-containing material W1, and the zinc-containing combustion exhaust gas is discharged into the secondary combustion chamber 31. In the secondary combustion chamber 31, combustible substances in the combustion exhaust gas are subjected to secondary combustion, the remaining fly ash Fa containing zinc is discharged from the secondary combustion chamber 31, and the fly ash Fa is captured by the bag filter 17.

  Zinc-containing fly ash Fa captured by the bag filter 17 is supplied to the solid reduction tank 37, and the zinc in the fly ash Fa is vaporized using preheated air as a heat source (vaporization step). The solid reduction tank 37 needs to be maintained at about 1200 ° C. to 1300 ° C. When the temperature becomes unstable only by preheated air, the auxiliary reduction burner 37d is used to place the solid reduction tank 37 at about 1200 ° C. to 1300 ° C. Hold on. Further, the solid reduction tank 37 is maintained in a reducing atmosphere, and the zinc in the fly ash Fa is melted and reduced and then vaporized and supplied to the splash condenser 23.

  In the splash condenser 23, the vaporized zinc is condensed and recovered as crude zinc Z1. Further, the zinc that could not be condensed by the splash condenser 23 is supplied to the zinc cooling unit 24 and cooled, and is precipitated and separated in the precipitation tank 25 of the zinc cooling unit 24 to be recovered as high-purity zinc Z2 (recovery step).

  According to the zinc recovery device 5C described above, at least zinc is vaporized among the metals contained in the fly ash Fa discharged from the secondary combustion chamber 31 of the kiln rotary furnace 3B, and the vaporized zinc is splashed into the splash condenser 23 or the zinc cooling. Since it is recovered by the unit 24, there is little mixing of impurities, and zinc can be efficiently recovered in a state suitable for reuse. Usually, a zinc refining manufacturer or the like does not purchase a raw material unless the zinc concentration is at least 50%. Therefore, if the fly ash Fa is to be processed, it is necessary to have an outside contractor or the like process it for a fee. However, in this embodiment, since zinc can be efficiently recovered from the fly ash Fa, it becomes possible to recover zinc having a high concentration of 80% or more, and it can also be sold as a zinc raw material to a zinc refining manufacturer. There are also significant economic advantages in terms of cost.

  Furthermore, since zinc is vaporized by using preheated air as a heat source, consumption of new fuel for obtaining the heat source can be suppressed, and zinc can be recovered efficiently.

  Further, in the present embodiment, similarly to the first embodiment, the splash condenser 23 is arranged on the upstream side where vaporized zinc flows, and the zinc cooling unit 24 is arranged on the downstream side. Therefore, the vaporized zinc is splashed into the splash condenser. Since the remaining zinc that has not been condensed by the splash condenser 23 is solidified and recovered by the zinc cooling unit 24, the vaporized zinc can be recovered efficiently without escaping.

  Further, in the zinc cooling unit 24, gaseous zinc is cooled and solidified by makeup water (cooling water) W, and the chlorine content is washed and removed by the makeup water W. In recent years, waste plastics are often used as an alternative fuel from the viewpoint of saving fossil fuels and effectively using waste in steelmaking processes, etc., and the chlorine content in fly ash Fa recovered by the bag filter tends to increase. It is in. If the chlorine content is high, there will be a problem of chlorination at the zinc refining manufacturer, and the zinc raw material will be of low quality. In the present embodiment, by providing the zinc cooling unit 24, the chlorine content is washed and removed by the makeup water W, so that high-quality zinc Z2 can be recovered.

  Moreover, since the zinc-containing exhaust gas discharged from the splash condenser 23 is introduced into the ejector 26a, the gaseous zinc is cooled in contact with the makeup water W efficiently while being stirred by the ejector 26a. As a result, the phase transition from the gas to the solid is efficiently performed, and further, the precipitate is separated in the precipitation tank, so that the solid zinc having high purity can be efficiently recovered.

(Fourth embodiment)
Next, a zinc recovery system according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram schematically showing a zinc recovery system according to the fourth embodiment. Note that in the fourth embodiment, elements that are substantially the same as in the first embodiment and the third embodiment are denoted by the same reference numerals, and a detailed description thereof is omitted.

  As shown in FIG. 11, the zinc recovery system 1D includes a kiln rotary furnace 3B including a roasting furnace 29 and a secondary combustion chamber 31, and a zinc recovery device 5D. The zinc recovery device 5 </ b> D is vaporized by heating in the solid reduction tank 37 that contains the zinc-containing fly ash Fa, the FA supply device 21 that supplies zinc-containing fly ash Fa to the solid reduction tank 37, and heating in the solid reduction tank 37. A splash condenser 23 for condensing the recovered zinc and recovering it as crude zinc Z1.

  In the present embodiment, unlike the third embodiment, there is no zinc cooling unit that solidifies and collects the remaining zinc discharged from the splash condenser 23. Instead, the exhaust gas from the splash condenser 23 is not recovered. An exhaust gas return line 39 for returning to the next combustion chamber 31 is provided.

  In the zinc recovery apparatus 5D according to the present embodiment, as in the third embodiment, at least zinc of the metal contained in the fly ash Fa discharged from the secondary combustion chamber 31 of the kiln rotary furnace 3B is vaporized and vaporized. Since the collected zinc is recovered by the splash condenser 23, there is little mixing of impurities, and zinc can be efficiently recovered in a state suitable for reuse.

(Fifth embodiment)
Next, a zinc recovery system according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a diagram schematically showing a zinc recovery system according to the fifth embodiment. Note that in the fifth embodiment, elements that are substantially the same as those in the first embodiment and the third embodiment are denoted by the same reference numerals, and a detailed description thereof is omitted.

  As shown in FIG. 12, the zinc recovery system 1E includes a kiln rotary furnace 3B including a roasting furnace 29 and a secondary combustion chamber 31, and a zinc recovery device 5E. The zinc recovery device 5E includes a solid reduction tank 37 that contains zinc-containing fly ash Fa, an FA feeder 21 that supplies zinc-containing fly ash Fa to the solid reduction tank 37, and zinc vaporized in the solid reduction tank 37. There is provided a zinc precipitation tank 25 that is cooled and solidified by the makeup water W, and further precipitates and separates from the makeup water W to recover high-purity zinc Z2.

  In the present embodiment, unlike the fourth embodiment, the splash condenser 23 is not provided, and the exhaust gas containing zinc vaporized in the solid reduction tank 37 is directly introduced into the ejector 26a for circulating the makeup water W. ing.

  Even in the zinc recovery apparatus according to the present embodiment, at least zinc of the metal contained in the fly ash Fa discharged from the secondary combustion chamber 31 of the kiln rotary furnace 3B was vaporized and vaporized, as in the third embodiment. Since zinc is recovered by the zinc cooling unit 24, there is little contamination of impurities, and zinc can be recovered efficiently in a state suitable for reuse.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. For example, in the zinc recovery apparatus according to the first embodiment or the second embodiment, the splash condenser is provided as the recovery means, but zinc may be recovered by the zinc cooling unit without providing the splash condenser. Moreover, in 1st Embodiment and 3rd Embodiment, although the splash condenser was arrange | positioned upstream and the sedimentation tank was arrange | positioned downstream, a zinc cooling unit is arrange | positioned upstream and a splash condenser is arrange | positioned downstream. An aspect may be sufficient.

It is a figure showing roughly the zinc recovery system concerning a 1st embodiment of the present invention. It is sectional drawing which shows typically the kiln rotary furnace which concerns on this embodiment. It is sectional drawing along the III-III line of FIG. It is a figure showing typically the zinc recovery device concerning this embodiment. It is a figure which shows typically the splash capacitor | condenser which concerns on this embodiment. It is a figure which shows melting | fusing point, boiling point, and equilibrium vapor pressure of each metal. It is a figure showing roughly the zinc recovery system concerning a 2nd embodiment of the present invention. It is a figure showing roughly the zinc recovery system concerning a 3rd embodiment of the present invention. It is sectional drawing which shows typically the kiln rotary furnace which concerns on this embodiment. It is a figure showing typically the zinc recovery device concerning this embodiment. It is a figure which shows schematically the zinc collection | recovery system which concerns on 4th Embodiment of this invention. It is a figure showing roughly the zinc recovery system concerning a 5th embodiment of the present invention.

Explanation of symbols

  3A, 3B ... Kiln rotary furnace (roasting device), 5A, 5B, 5C, 5D, 5E ... Zinc recovery device, 7, 29 ... Roasting furnace, 9, 31 ... Secondary combustion chamber, 11 ... Molten slag separator , 19 ... Smelting reduction tank (heating chamber), 37 ... Solid reduction tank (heating chamber), 23 ... Splash condenser (recovery means), 24 ... Zinc cooling unit (recovery means, cooling means), 25 ... Precipitation tank, 26a ... Ejector 35 ... Preheated air pipe (heat exchange part) 37a ... Fly ash accommodating chamber (accommodating part), Fa ... Fly ash (ash containing zinc), Z1 ... Crude zinc, Z2 ... Zinc.

Claims (10)

In a zinc recovery device that recovers zinc from zinc-containing ash,
A heating chamber that contains and heats the ash, and vaporizes at least the zinc in a reducing atmosphere among the metals contained in the ash;
Recovery means for recovering the zinc vaporized in the heating chamber;
A zinc recovery apparatus comprising: The ash is discharged from a roasting apparatus equipped with a roasting furnace for roasting zinc-containing materials,
The zinc recovery apparatus according to claim 1, wherein the heating chamber contains molten slag discharged from the roasting furnace, and heats the ash by the molten slag.   A molten slag separation unit that separates the molten material discharged from the roasting furnace into molten metal and the molten slag by a specific gravity difference, and supplies the molten slag having a low specific gravity separated from the molten metal to the heating chamber. The zinc recovery apparatus according to claim 2, further comprising:   The zinc recovery apparatus according to any one of claims 1 to 3, wherein the recovery means includes a splash condenser that stores molten zinc and condenses the zinc vaporized in the heating chamber.   The zinc recovery apparatus according to any one of claims 1 to 4, wherein the recovery means includes a cooling means for cooling the zinc vaporized in the heating chamber to cause a phase transition from a gas to a solid. The cooling means is in contact with gaseous zinc and stores cooling water that causes phase transition of the zinc from a gas to a solid, and is extracted from a precipitation tank that precipitates and separates the zinc in the cooling water, and the precipitation tank. An ejector for injecting cooling water into the settling tank,
The zinc recovery apparatus according to claim 5, wherein the gaseous zinc is introduced into the ejector and mixed with stirring in the cooling water. The ash is discharged from a roasting apparatus equipped with a roasting furnace for roasting zinc-containing materials,
The heating chamber includes: a housing unit that houses the ash; and a heat exchange unit that heats the ash housed in the housing unit by preheated air heated by the roasting device. The zinc recovery apparatus according to claim 1.   8. The zinc recovery apparatus according to claim 7, wherein the recovery means has a splash condenser that stores molten zinc and condenses the zinc vaporized in the heating chamber.   The zinc recovery apparatus according to claim 7 or 8, wherein the recovery means includes a cooling means for cooling the zinc vaporized in the heating chamber to cause phase transition from gas to solid. The cooling means is in contact with gaseous zinc and stores cooling water that causes phase transition of the zinc from a gas to a solid, and is extracted from a precipitation tank that precipitates and separates the zinc in the cooling water, and the precipitation tank. An ejector for injecting cooling water into the settling tank,
The zinc recovery apparatus according to claim 9, wherein the gaseous zinc is introduced into the ejector and stirred and mixed with the cooling water.

Images