JPH1017949A - Vacuum heat treating device of powder and granular material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover valuable metals at a high yield by supplying a prescribed amt. of a reducing gas as a carrier gas for the metal vapor generated from powder and granular materials to a treating chamber. SOLUTION: The treating chamber 23 is evacuated to vacuum and a heater 33 is operated to maintain the treating chamber 23 at a prescribed temp. A valve 43a is opened to drop the powder and granular materials from a hopper 15 to a plate 111 of the uppermost stage and a valve 53a is opened to supply the reducing gas from plural nozzles 53b. The dropped powder and granular materials are extruded to fall onto the plate 112 of the lower stage while the powder and granular materials are agitated on the plate 111 and are simultaneously spread thin. Henceforce, the powder and granular materials are successively dropped to the lower stages in the same manner and are finally dropped to a discharge chute 23a. When the reducing gas is supplied as the carrier gas to the surfaces of the powder and granular materials in such a state, the temp. boundary layers of the metal vapor formed around the powder and granular materials are made sufficiently thinner or are substantially destroyed. The zinc, lead, etc., in the powder and granular materials are efficiently and rapidly evaporated and are recovered into a condenser 73.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum heat treatment apparatus for granular materials. For example, dust captured by a dust collector in a steelmaking plant contains metal oxides such as iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ), zinc oxide (ZnO), and lead oxide (PbO). I have. Discarding such dust as it is wastes resources, and it is desired to recover valuable metals such as iron, zinc and lead from the dust. The present invention relates to an apparatus for recovering valuable metals such as iron, zinc, and lead from a granular material represented by dust as described above by heat-treating the granular material in a vacuum atmosphere.

[0002]

2. Description of the Related Art Conventionally, as a vacuum heat treatment apparatus for recovering valuable metals such as iron, zinc, and lead from powders and granules, a closed vessel and a treatment chamber formed by being surrounded by a heat insulating material in the vessel are known. ,
It is proposed to provide a heater provided in the processing chamber, a vacuum pump connected to the container to make the processing chamber a vacuum atmosphere, and a condenser interposed between the container and the vacuum pump. As a condenser used in such a vacuum heat treatment apparatus, a water-cooled condensation chamber, a first vacuum chamber formed below the condensation chamber, and a first vacuum chamber are described. And a second vacuum chamber formed in the lower part of the device (Japanese Utility Model Laid-Open No. 5-30149). In this conventional apparatus, powder and granules are supplied to a processing chamber, and heat treatment is performed in a vacuum atmosphere to condense generated zinc and lead vapors in a condenser while leaving iron in the processing chamber. . However, this conventional apparatus actually has a problem that valuable metals such as iron, zinc, and lead cannot be recovered from the granular material with a high yield, and the recovery takes time.

[0003]

The problem to be solved by the present invention is that the conventional apparatus cannot recover valuable metals such as iron, zinc, lead and the like from the granular material in a high yield, and the recovery thereof It takes time.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an apparatus for recovering valuable metal from a granular material by heating the granular material under a vacuum atmosphere in a processing chamber formed in a closed vessel. And supplying the processing chamber with a sufficient amount of reducing gas as a carrier gas for the metal vapor generated from the powder or granules to sufficiently thin or substantially destroy the concentration boundary layer of the metal vapor. The present invention relates to a vacuum heat treatment apparatus for a granular material characterized by comprising:

[0005] Also in the present invention, a closed system container, a processing chamber surrounded by a heat insulating material in the container, a heating source provided in the processing chamber, and a processing source connected to the container. A vacuum pump for evacuating the chamber to a vacuum atmosphere, and a condenser interposed between the container and the vacuum pump are provided.

According to the present invention, a reducing gas such as H ₂ gas, CO gas, RX gas or the like is used as a carrier gas for metal vapor generated from the granular material in the processing chamber of the container, and the concentration boundary layer of the metal vapor is sufficiently increased. And is configured to provide an amount sufficient to make it thin or substantially destroyed. When the powder is heat-treated in a vacuum atmosphere in a processing chamber, a metal vapor such as zinc or lead is generated from the powder. The reducing gas supplied as a carrier gas from the metal vapor around the powder is used as a carrier gas. To lower the concentration of metal vapor around the granules,
That is, the partial pressure of the metal vapor is lowered to promote the evaporation of the metal from the granular material. Generally, the evaporation of the metal from the granular material depends on the concentration of the metal vapor formed around the granular material. It is greatly influenced by the boundary layer, and when the concentration boundary layer is thick, the evaporation of the metal from the granular material becomes slower, and conversely, when the concentration boundary layer is thin, the evaporation of the metal from the granular material becomes faster. Supply sufficient reducing gas to sufficiently thin or substantially destroy the concentration boundary layer of the metal vapor formed around the granules.

[0007] In order to make the concentration boundary layer of the metal vapor formed around the granular material easy to be sufficiently thin or to be substantially broken, reducing gas is added to each part of the granular material in the processing chamber. Is preferably supplied, or the granules are preferably agitated in the processing chamber, but it is particularly preferable that the granules are spread thinly and stirred in the processing chamber. It is preferable to supply the reducing gas toward the powdery particles in the state in which the particles are kept.

Therefore, according to the present invention, a reducing gas supply pipe is inserted into the processing chamber, a plurality of nozzles are attached to the reducing gas supply pipe, and the reducing gas is supplied from the nozzles into the particles in the processing chamber. Preferably, in this case, it is more preferable to stir the granules in the processing chamber. Further, in the present invention, a plurality of plates are arranged in the processing chamber in multiple stages at predetermined intervals, and the stirring member and the transfer member are rotatably arranged near the upper surface of each of the plates, and the uppermost plate It is preferable to stir the powder and granules supplied to the stirring member by the stirring member, and simultaneously spread the thinner and thinner by the transfer member and successively drop it to the lower plate to perform a continuous heat treatment. It is preferable that a reducing gas supply pipe is inserted, a plurality of nozzles are attached to the reducing gas supply pipe, and the reducing gas is supplied from the nozzles toward the particles on each plate.

Further, in the present invention, the supply of the reducing gas to the processing chamber and the exhaust from the processing chamber can be kept constant, and the pressure in the processing chamber can be kept constant. Alternatively, the pressure in the processing chamber is preferably repeatedly changed by intermittently adjusting exhaust gas from the processing chamber. This is because the metal vapor trapped between the powders can be forcibly entrained in the reducing gas and recovered.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall view partially illustrating a vacuum heat treatment apparatus according to the present invention in a longitudinal section. A heat insulating material 11a is lined with a closed system container 11, and the heat insulating material 11a
, A processing chamber 21 is formed, and a tube heater 31 is inserted into the processing chamber 21. A powder supply pipe 41 communicating with the processing chamber 21 is connected to the upper surface of the container 11, and a valve 41 a is interposed in the powder supply pipe 41. A reducing gas supply pipe 51 is provided on the upper left side of the container 11.
Is connected, and the reducing gas supply pipe 51 is connected to the processing chamber 21.
Are inserted into the lower part through the center of the nozzle, and a plurality of nozzles 51 having different lengths are inserted into the inserted reducing gas supply pipe 51.
b is attached. A valve 51 a is interposed in the reducing gas supply pipe 51, and a reducing gas supply source (not shown) is connected upstream of the reducing gas supply pipe 51.
An exhaust pipe 61 communicating with the processing chamber 21 is connected to an upper right portion of the container 11, and a valve 61 a is interposed in the exhaust pipe 61. A condenser 71 is connected downstream of the exhaust pipe 61, and a vacuum pump 81 is connected downstream of the condenser 71.

FIG. 2 is an overall view partially exemplifying another vacuum heat treatment apparatus according to the present invention in a longitudinal section. A heat insulating material 12a is lined in a closed container 12 formed as a whole in a cylindrical shape, and a processing chamber 22 is formed surrounded by the heat insulating material 12a. A panel heater 32 is provided inside the heat insulating material 12a. Has been established. A powder supply pipe 42 communicating with the processing chamber 22 is connected to the upper surface of the container 12, and a valve 42 a is interposed in the powder supply pipe 42. An inclined surface descending toward the axis is formed at a lower portion of the container 12, and an outlet 22 communicating with the processing chamber 22 is provided at a lower end of the inclined surface.
a has been established. The outlet 22a is connected to a discharge pipe 13 having an inclined surface rising toward the axis, and the discharge pipe 13 is provided with a valve 13a. An exhaust pipe 63 is connected to the upper part on the right side of the large-diameter portion of the exhaust pipe 13, and a downstream side of the exhaust pipe 63 is a valve 6.
It is connected to a vacuum pump 82 via 3a.

An exhaust pipe 62 communicating with the processing chamber 22 is connected to an upper portion on the right side of the container 12, and the exhaust pipe 62 is provided with a valve 62a. A condenser 72 is connected downstream of the exhaust pipe 62, and a vacuum pump 82 is connected downstream of the condenser 72. A reducing gas supply pipe 52 is connected to the lower inclined surface of the container 12, and the reducing gas supply pipe 52 is inserted upward through the side of the processing chamber 22, and the inserted reducing gas A plurality of nozzles 52b are attached to the gas supply pipe 52. A valve 52a is interposed in the reducing gas supply pipe 52, and a reducing gas supply source (not shown) is connected upstream of the reducing gas supply pipe 52.

A rotary cylinder 91 is inserted into the processing chamber 22 along the axis thereof, and a plurality of plate-like blades 92 are mounted on the rotary cylinder 91. The rotating cylinder 91 is supported by the container 12, and the upper part thereof is taken out of the container 12 and connected to a drive motor 93. An elevating shaft 94 is inserted through the rotating cylinder 91, and the upper part thereof is taken out of the rotating cylinder 91 and connected to a cylinder mechanism 95. Elevating shaft 94
The lower part of the valve 9 reaches the discharge pipe 13 through the outlet 41, and the valve 9 having an inclined surface formed at the end thereof rising toward the axis.
6 are attached. When the lifting shaft 94 moves up, the valve 9
6 is close to the inclined surface of the discharge pipe 13 and the outlet 22a
Is closed, and when the elevating shaft 94 descends, the inclined surface of the valve 96 is separated from the inclined surface of the discharge pipe 13 to open the outlet 22a.

FIG. 3 is an overall view partially illustrating a further example of a vacuum heat treatment apparatus according to the present invention in a longitudinal section, FIG. 4 is a partially enlarged longitudinal sectional view showing the internal structure of the same vacuum heat treatment apparatus as FIG.
3 is a partially enlarged horizontal sectional view showing the internal structure of the same vacuum heat treatment apparatus as FIG. 3, and FIG. 6 is a partially enlarged vertical sectional view showing the internal structure of the same vacuum heat treatment apparatus as FIG. In FIG. 3, a heat insulating material 1 is placed in a closed container 14 having a cylindrical shape as a whole.
4a is lined, and a heat insulating material 14a
A processing chamber 23 is formed, and a tube heater 33 is provided in the processing chamber 23. The axis of the container 14 passes through the heat insulating material 14a and the processing chamber 23, and the rotating shaft 1
The rotation shaft 110 is connected to a drive shaft (not shown) of a drive motor 110 a attached to the container 14.

In the processing chamber 23, plates 111 to 119 are arranged at predetermined intervals in a total of nine stages in the vertical direction. The plates 111 to 119 are formed in a disc shape having the same diameter, The bearing is mounted on the rotating shaft 110 at the portion. Disc-shaped plates 111 to 11 having the same diameter
9 are arranged around the same axis. On the periphery of the plates 111 to 119, ring-shaped wall pieces 111a, 1
, And the wall piece 11 is provided.
.. Are attached to a bar 110b mounted in the vertical direction of the container 14. Therefore, the plates 111 to 119 are supported by the rotating shaft 110, but do not rotate when the rotating shaft 110 rotates.

The openings 111 are provided in the plates 111 to 119.
, 114b, 119b, ... are provided in a slit shape along the radial direction. Openings 111b, 114
, are sequentially arranged from the uppermost plate 111 to the lowermost plate 119.
Is provided at a position deviated in the direction opposite to the rotation direction of the.
4 and 5, the rotation shaft 110 rotates clockwise when viewed from the plane, but the opening 1
11 b is provided at a position counterclockwise from immediately below the granular material supply pipe 43 facing the plate 111, and the opening (not shown) of the second stage plate 112 is
The opening 111b is located further counterclockwise than the opening 111b. Similarly, from the third stage plate 113 to the lowermost stage plate 119, these openings are sequentially provided at leftwardly shifted positions. Of these, the fourth stage plate 114 is provided. The opening 114b is provided on the rightmost side, and the opening 1b of the lowermost plate 119 is formed.
19b is provided on the leftmost side, and the opening 119b is located immediately above the discharge chute 23a formed in a funnel shape.

4 to 6, the plates 111, 1
Are arranged on the upper surfaces of 14, 119,... Provided with two comb-like objects each having a plurality of projecting bars in close proximity to them. The transfer members 131, 134, 139,... Each having two blades are disposed at a position slightly clockwise from the stirring members 121, 124, 129,. The stirring members 121, 124, 129,... And the transfer members 131, 134, 139,.
10, which rotate integrally with the rotating shaft 110. For example, the rotating shaft 110
Is rotated intermittently in the forward direction as a whole while rotating in the forward and reverse directions, that is, as the whole is intermittently rotated clockwise while the rotation shaft 110 is alternately rotated clockwise and counterclockwise. , Stirring members 121, 124, 129,
... and transfer members 131, 134, 139, ...
Also intermittently rotate in the forward direction as a whole while rotating in the forward and reverse directions, ie, the stirring members 121, 124, 12
9, and the transfer members 131, 134, 139,.
・ ・ Also intermittently rotate clockwise as a whole while rotating clockwise and counterclockwise alternately.

A powder supply pipe 43 is inserted into the processing chamber 23 so as to face the uppermost plate 111 directly below. The powder supply pipe 43 provided with a valve 43 a is connected to the hopper 15. The valve 15a is located upstream of the hopper 15.
Is connected to the powder supply pipe 15b. An exhaust pipe 66 is connected to the upper right side of the hopper 15.
The exhaust pipe 66 is provided with a valve 66a, and the downstream side of the exhaust pipe 66 is connected to a vacuum pump 83. The processing chamber 23 has an opening 11 of the lowermost plate 119.
A funnel-shaped discharge chute 23a is arranged facing 9b directly above. The discharge chute 23a is connected to a discharge pipe 23c having a valve 23b interposed therebetween.
Is connected to a hopper 16, and a discharge pipe 16b provided with a valve 16a is connected downstream of the hopper 16. An exhaust pipe 65 is connected to the upper right side of the hopper 16, and a valve 65 a is interposed in the exhaust pipe 65, and the downstream side of the exhaust pipe 65 is connected to a vacuum pump 83.

An upper portion of the right side of the container 14 is connected to an exhaust pipe 64 communicating with the processing chamber 23. The exhaust pipe 64 is provided with a valve 64a. A condenser 73 is connected downstream of the exhaust pipe 64, and a vacuum pump 83 is connected downstream of the condenser 73. A reducing gas supply pipe 53 is inserted into the processing chamber 23, and a plurality of nozzles 53b are attached to the inserted reducing gas supply pipe 53.
11 to 119. Reducing gas supply pipe 5
3 is provided with a valve 53 a, and a reducing gas supply source (not shown) is connected upstream of the reducing gas supply pipe 53.

A case will be described in which the granular heat treatment is performed in a vacuum atmosphere by using the vacuum heat treatment apparatus according to the present invention described with reference to FIGS. With the valve 15a opened and the valve 43a closed, the granular material is put into the hopper 15. Valve 15a,
43a, 16a are closed and valves 66a, 23b, 65a
Is opened, the vacuum pump 83 is operated, and the processing chamber 2 is opened.
The inside of the chamber 3 and the hoppers 15 and 16 are set to a vacuum atmosphere, and the drive motor 110a and the tube heater 33 are operated. When the temperature inside the processing chamber 23 reaches a predetermined temperature, the valve 43a is opened and the uppermost plate 11 is opened from the hopper 15.
1 and the valve 53 a is opened, and the reducing gas is supplied from the plurality of nozzles 53 b through the reducing gas supply pipe 53. The dropped powder is plate 1
It is agitated by the agitating member 121 on the surface 11, and at the same time, is extruded while being thinly spread by the transfer member 131, and drops from the opening 111 b of the plate 111 to the second-stage plate 112. The dropped powder is plate 1
Similarly, the mixture is extruded while being agitated and spread at the same time, and falls from the opening of the plate 112 to the third plate 113. In the same manner as described above, the granular material sequentially falls to the lower plate, and finally falls from the opening 119b of the lowermost plate 119 to the discharge chute 23a. The powdery and granular materials are agitated on the upper surfaces of the plates 111 to 119 having a total of nine steps, 121, 124, 129,.
.. Repeatedly agitated and simultaneously transferred member 13
1, 134, 139,... Are repeatedly spread thinly. In addition, a total of 9 stages of plates 111 to 11
119, a reducing gas is supplied as a carrier gas from each of the nozzles 53b to the surface of the granular material which is agitated and spread thinly at the same time as described above, whereby the metal vapor formed around the granular material is supplied. The concentration boundary layer is made sufficiently thin or substantially destroyed. Zinc, lead and the like in the powder and particles evaporate very efficiently and in a short time, and these metal vapors are collected in the condenser 73. Discharge chute 23a
The treated material that falls into the container is, for example, iron remaining after evaporating zinc, lead, and the like from the powder and granular material. After the treated material is stored in the hopper 16, the valve 23b is closed, and the pressure inside the hopper 16 is restored. Open and remove 16a.

FIG. 7 is a graph schematically showing the pressure fluctuation in the processing chamber when the reducing gas is intermittently supplied to the processing chamber in the vacuum heat treatment apparatus according to the present invention as shown in FIGS. . In FIG. 7, the exhaust from the processing chamber is kept constant. As shown in FIG. 7, when the pressure in the processing chamber is repeatedly changed, the metal vapor trapped between the particles can be forcibly collected together with the reducing gas, so that the valuable metal can be recovered more efficiently. . The pressure fluctuation in the processing chamber as shown in FIG. 7 may be caused by the supply of the reducing gas to the processing chamber or the exhaust of the reducing gas from the processing chamber, including the case where the reducing gas is intermittently supplied to the processing chamber. It can be achieved by intermittent adjustments, such adjustments being made by the valves 51a, 52 of FIGS.
This can be achieved by adjusting the opening of the valves a, 53a or the valves 61a, 62a, 64a.

Using the vacuum heat treatment apparatus described above with reference to FIGS. 3 to 6, a mixture of coke as a reducing agent and zinc having a zinc content of 7.0% by weight captured by a dust collector at a steelmaking plant was subjected to a vacuum of 2 Torr. After heating at 900 ° C. for 2 hours in the processing chamber, the residual zinc content in the processed material dropped from the discharge chute to the hopper was 0.4% by weight. On the other hand, when a reducing gas was not supplied as a carrier gas and heat treatment was carried out under the same conditions as above, the residual zinc content in the treated product was 1.7% by weight.

[0023]

As is clear from the above, the present invention described above has an effect that valuable metals can be recovered from powders and granules in high yield in a short time.

[Brief description of the drawings]

FIG. 1 is an overall view partially illustrating a vacuum heat treatment apparatus according to the present invention in a longitudinal section.

FIG. 2 is an overall view exemplifying a partial longitudinal section of another vacuum heat treatment apparatus according to the present invention.

FIG. 3 is an overall view exemplifying still another vacuum heat treatment apparatus according to the present invention in a partial longitudinal section.

FIG. 4 is a partially enlarged longitudinal sectional view showing the internal structure of the same vacuum heat treatment apparatus as in FIG.

FIG. 5 is a partially enlarged cross-sectional view showing the internal structure of the same vacuum heat treatment apparatus as in FIG.

FIG. 6 is a partially enlarged longitudinal sectional view showing the internal structure of the same vacuum heat treatment apparatus as FIG. 3 from another angle.

FIG. 7 is a graph schematically showing pressure fluctuation in the processing chamber when a reducing gas is intermittently supplied to the processing chamber in the vacuum heat treatment apparatus according to the present invention.

[Explanation of symbols]

11, 12, 14 ... container, 11a, 12a, 14a
... heat insulating material, 21, 22, 23 ... processing chamber, 31,
33: tube heater, 32: panel heater,
51, 52, 53 ... reducing gas supply pipe, 51b, 5
3b: nozzle, 71, 72, 73: condenser, 8
1, 82, 83: vacuum pump, 92: blade, 1
11 to 119: plate, 121, 124, 129
... Stirring members, 131, 134, 139 ... Transfer members

Claims (5)

[Claims] 1. An apparatus for heating a granular material under a vacuum atmosphere in a processing chamber formed in a closed container to recover valuable metal from the granular material, wherein the processing chamber comprises Characterized in that a sufficient amount of reducing gas is supplied as a carrier gas for the metal vapor generated from the body so as to sufficiently thin or substantially destroy the concentration boundary layer of the metal vapor. Vacuum heat treatment equipment for body. 2. A reducing gas supply pipe is inserted into the processing chamber, and a plurality of nozzles are attached to the reducing gas supply pipe, and the reducing gas is supplied from the nozzles into the particles in the processing chamber. The vacuum heat treatment apparatus for a granular material according to claim 1, wherein the powder is supplied. 3. A plurality of plates are arranged in a multistage manner at a predetermined interval in a processing chamber, and a stirring member and a transfer member are rotatably arranged close to respective upper surfaces of the plates. 2. The powdery material supplied to the upper plate is agitated by the agitating member, and is simultaneously dropped on the lower member while being spread thinly by the transferring member, so as to be continuously heated. Vacuum heat treatment equipment for granular materials. 4. A reducing gas supply pipe is inserted into the processing chamber, and a plurality of nozzles are attached to the reducing gas supply pipe. The vacuum heat treatment apparatus for a granular material according to claim 3, wherein a neutral gas is supplied. 5. The vacuum heat treatment apparatus for granular material according to claim 1, wherein the pressure in the processing chamber is repeatedly changed by intermittently adjusting the supply or exhaust of the reducing gas.