JP4370401B2 - Smelting furnace and platinum group element recovery method using the same - Google Patents

Description

The present invention relates to a metal smelting furnace having a furnace wall that replaces a refractory by an iron skin and a water film flow, and further relates to a method for recovering platinum group elements using the smelting furnace.

Most metal smelting furnaces have an in-furnace temperature exceeding 1000 ° C., and it is therefore necessary to protect the furnace body by means of heat shielding or cooling. As a method for protecting such a furnace body, the lining of the refractory material on the inner wall surface of the furnace has been most commonly performed conventionally, and the outer wall surface of the furnace is blown, water-cooled jacket, oil-cooled jacket, etc. It is also arranged and cooled.

Refractory materials that protect the furnace interior are exposed to harsh environments such as high temperatures and erosion, so if they are damaged such as collapse or melting, the operation is stopped and repair work is required if it exceeds the limit. To do. In a smelting furnace in which the oxide raw material charged in the furnace is reduced with a carbonaceous reducing agent to obtain a molten metal, the refractory in the furnace is likely to be damaged, and its repair requires a large amount of cost. It had been.

In Patent Document 1 and Patent Document 2 by the same applicants, a smelting furnace (electric furnace) equipped with an electrode is mixed with an oxide-based material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing material, and a flux. A method is described in which the furnace interior charge is melted and reduced by energizing and heating the furnace interior with the electrodes. Even if the inner wall of such an electric furnace is lined with a sufficiently thick refractory material, the height level where the molten slag layer exists and the refractories on the inner wall at the upper level are significantly damaged. The inventors have learned to receive.
JP-A-4-317423 JP 2000-248322 A

Therefore, the present invention avoids damage to the inner wall including at least the molten slag level in a smelting furnace that obtains a molten metal by reducing the oxide raw material charged in the furnace with a carbonaceous reducing agent. More specifically, a smelting furnace (electric furnace) equipped with electrodes is charged with an oxide-based material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing material, and a flux. Therefore, it is intended to provide a method for recovering platinum group elements with good operability by avoiding the problem of damage to the inner wall during smelting.

According to the present invention, in a smelting furnace for obtaining a molten metal by reducing an oxide raw material charged in a furnace with a carbonaceous reducing agent, a furnace including a height level of a molten slag layer generated in the furnace. The wall is composed of an iron skin, and a water film flow descending in contact with the outer surface is formed on the outside of the iron skin, and further, a solidified layer of the melt in the furnace is formed on the inner surface of the furnace. A smelting furnace characterized by producing a self-coating layer is provided. Here, the water film flow descending in contact with the outer surface of the iron skin is transferred from the header installed on the outer upper part of the furnace wall toward the entire outer circumference of the same level of the iron skin. The water should be evenly distributed. The smelting furnace can be a closed electric furnace having an electrode for energizing and heating the furnace interior material and a lid for substantially shutting off the furnace interior material from the outside atmosphere. .

Furthermore, according to this invention, the recovery method of the platinum group element using the said smelting furnace is provided. Specifically, it is a sealed electric furnace comprising an electrode for energizing and heating the furnace interior material and a lid for substantially shutting off the furnace interior material from the outside air atmosphere. An electric furnace according to the present invention is used in which the furnace wall including the height level of the molten slag layer produced in step 1 is composed of iron skin, and a water film flow descending in contact with the outer surface is formed outside the iron skin. In addition, this electric furnace was charged with an oxide-based raw material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing material, and a flux, and these furnace interiors were electrically heated by the electrodes and melted. And a reduction treatment to form a molten metal layer below the molten slag layer, to concentrate the platinum group element in the molten metal, and to melt the in-furnace on the inner surface of the iron skin during the operation. A self-coating layer consisting of a solidified layer of To provide a method of recovering platinum group elements.

In this platinum group element recovery method, an oxide material, copper oxide, a solid carbonaceous reducing material and a flux are all prepared in the form of particulates, and these electrical particulates are mixed in advance before It is good to charge in the furnace, and after heating and melting the furnace interior material, after providing a standing step for holding at a temperature of 1200 to 1500 ° C. for at least 5 hours, a molten metal containing a platinum group element Should be discharged out of the furnace. At that time, the range of the component composition of the slag-based oxide generated in the furnace is Al ₂ O ₃ : 20 to 40 wt%, SiO ₂ : 25 to 40 wt%, CaO: 20 to 35
It is preferable to control wt% and FeO: 0 to 35 wt%.

FIG. 1 shows an example of a smelting furnace according to the present invention. The smelting furnace of FIG. 1 includes an electrode 2 for energizing and heating the furnace interior material 1 and a lid 3 for substantially blocking the furnace interior material 1 from the outside air atmosphere at the upper part of the furnace body 4. It is a closed electric furnace. The furnace interior material 1 is composed of a mixture of an oxide raw material, a carbonaceous reducing agent, and a flux. The furnace interior material 1 is melted by energization from the electrode 2 to form the molten slag layer 5, and at the same time, the molten metal 6 produced by reducing the oxide is stored below the molten slag layer 5. The generated molten slag layer 5 and molten metal 6 are appropriately discharged out of the furnace through the slag tapping port and the metal tapping port 8. Although not shown in the figure, the gas generated in the furnace is discharged outside the furnace through the exhaust gas path. FIG.
, 9 indicates a chute for material charging.

In the metal smelting furnace according to the present invention, the furnace wall including the height level of the molten slag layer 5 generated in the furnace is constituted by the iron shell 10, and the outer surface of the iron shell 10 is arranged outside the outer surface. A water film flow 11 that descends in contact with is formed. In the illustrated example, the furnace wall (the wall of the furnace excluding the furnace bottom and the ceiling cover 3) constituting the furnace body 4 is entirely composed of the iron skin 10. That is, not only the height level at which the molten slag layer 5 exists, but also the furnace wall above this (the furnace wall up to the portion in contact with the lid 3) is also composed of the iron shell 10. FIG. 2 schematically shows this state.

In FIG. 2, the entire furnace wall is formed of a cylindrical iron skin 10. When the furnace wall is constituted by the cylindrical iron skin 10 as described above, an annular header is formed on the outer upper portion of the iron skin 10 so as to surround the iron skin 10 and be separated from the iron skin 10 by a certain distance. 12 is similarly installed in the lower part of the outer side of the iron skin 10 so as to surround the iron skin 10 and in contact with the iron skin 10. Water is uniformly ejected from the header 12 toward the entire outer peripheral surface of the iron skin 10, thereby forming a curtain-like water film flow that falls along the outer surface of the iron skin 10. The coming water film flow is received by the annular trough 13.

In this way, by forming a continuous water film flow 11 (FIG. 1) on the outer surface of the iron skin 10, the inner surface of the iron skin 10 is continuously cooled, so that the melting generated in the furnace The slag solidifies to form a self-coating layer 14 (FIG. 1) having a predetermined thickness. This self-coating layer 14 may be formed not only on the presence level of the molten slag layer 7 in the furnace, but also on the inner surface above it. Therefore, even if the lining of the furnace wall is omitted during the construction of the furnace, a self-coating layer 14 composed of a solidified layer of the slag is formed inside the iron shell 10 mainly at the level of the molten slag phase 7, which is the lining. To play a role. Even if a part of the self-coating layer 14 is damaged during the operation, the damaged part naturally recovers during the operation, so that repair work for the damaged part is performed as in the case of lining with a refractory. Is rarely needed.

FIG. 3 schematically shows a water treatment system when a continuous water film flow 11 is formed on the outer surface of the iron skin 10. As shown in FIG. 3, a slit-like nozzle port 15 is provided on the side of the iron skin 10 in the header 12 arranged on the peripheral surface of the iron skin 10 with the axis horizontal. When cooling water having a predetermined head pressure is supplied to the header 12, the cooling water flows out from the slit-shaped nozzle port 15 in the horizontal direction toward the iron skin 10 and falls while drawing a parabola. A steady annular flow is formed. A process in which the steady annular flow naturally contacts the cylindrical surface of the iron skin 10, that is, a phenomenon in which the annular flow does not rebound on the surface of the iron skin 10 and falls after reaching the iron skin 10. The distance between the iron skin 10 and the nozzle mouth 15 and the size of the nozzle mouth so as to flow over the whole iron skin 10 with a natural spread without leaving the iron skin 10 or branching or converging. The water pressure in the header and the amount of water to be supplied are determined. For this purpose, the temperature control of the cooling water and the control of the water amount and the water pressure are performed as follows.

The water film flow 11 flowing down along the outer surface of the iron skin 10 is received by the annular ridge 13 and then stored in the storage tank 16. The storage tank 16 is supplied with makeup water corresponding to evaporation loss from a makeup water channel 17. The hot water in the storage tank 16 is sent to the watering device 20 of the cooling tower 19 by the pump 18, and the hot water is cooled by exchanging heat with the outside air in the cooling tower 19. The cooled water is pumped into the head tank 22 by the metering pump 21 and then supplied into the header 12. At that time, the amount of water fed from the head tank 22 to the header 12 is controlled so that the water level in the header 12 is constant. As a result, cooling water with a constant pressure is discharged from the nozzle port 15, so that a continuous water film flow 11 is constantly formed on the surface of the iron skin 10. The water film flow 11 is constantly formed, so that the self-coating layer 14 is held inside the iron skin 10 with a certain thickness.

In the following, when such a smelting furnace is used, smelting that efficiently recovers useful metals such as platinum group elements from spent spent catalysts and the like can be realized. The recovery method will be described below.

As described above, in Patent Documents 1 and 2, a smelting furnace (electric furnace) equipped with electrodes is charged with an oxide-based material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing material, and a flux. In addition, a method is described in which these furnace interior materials are heated and energized by the electrodes to be melted and reduced. In carrying out this method, the inventors of the present invention have made the inner wall of the electric furnace lined with a refractory material having a sufficient thickness, and the molten slag layer and the gas phase layer located above the molten slag layer. Even when lining was applied using appropriate refractories, it was experienced that the refractories on the inner wall at the height level where the molten slag layer exists and at the upper level were significantly damaged.

According to the present invention, an electric furnace (for example, FIG. 1) according to the present invention is charged with an oxide-based material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing material, and a flux as the furnace interior material 1. Then, the furnace interior charge 1 is electrically heated by the electrode 2 to be melted and reduced to form a molten metal 6 layer below the molten slag layer 5, and a platinum group element is formed in the molten metal 6. It was found that the self-coating layer 14 was formed on the inner side of the iron skin 10 and the continuous operation could be efficiently performed with the iron coating 10 protected by the self-coating layer 14.

With such an electric furnace, the following modes of operation can be realized.

First, the platinum group element-containing material to be treated in the present invention is, for example, a used petrochemical waste catalyst containing platinum, palladium or the like, a spent automobile exhaust gas purification waste containing platinum, palladium or rhodium or the like. This includes not only catalysts but also lot-out products and scraps obtained from the manufacturing process of these catalysts, and also includes used electronic boards, dental parts, lead frames and the like containing palladium. Such a material to be treated containing a platinum group element is usually in a state where a trace amount of the platinum group element is supported on a metal oxide or ceramics.

These platinum group element-containing substances to be treated are introduced into a smelting furnace and melted together with a copper source material containing copper oxide, a flux and a carbonaceous reducing agent, and below the formed oxide-based molten slag layer. The molten metal layer mainly composed of copper metal is allowed to settle, and the platinum group element is concentrated in the molten metal layer that has settled downward. In this case, the present invention can adopt the following characteristic aspects. it can.

1. A closed smelting furnace is constructed with a steel wall as a smelting furnace, a continuous water film flow is formed on the outer surface of the iron skin, and a self-coating layer is formed on the inner surface of the iron skin. Use an electric furnace of the type.
2. The platinum group element-containing material, copper oxide-containing copper source material, solid carbonaceous reductant, and flux are all prepared in the form of powder, and these powder are mixed in advance. To charge the electric furnace.
3. After heating and melting the furnace interior material, after providing a standing step for holding at a temperature of 1200 to 1500 ° C. for at least 5 hours, the molten metal containing the platinum group element is discharged out of the furnace.
4. Component ranges of slag-based oxides generated in the furnace are Al ₂ O ₃ : 20-30 wt%, SiO ₂ : 25-40 wt%, CaO: 20-35 wt%, FeO: 0-35 wt% The raw material composition is adjusted so that
5. The content of at least one oxide of Al, Si, and Fe contained in the oxide-based material accompanied by the platinum group element is analyzed and grasped in advance, and the furnace according to the content of these oxides The component composition of the oxide raw material is controlled by adjusting the flux component composition to be charged into the material.
6. Slag separated from molten metal is
Al: 10 to 22 wt%,
Si: 10 to 16 wt%,
Ca: 14-22 wt%,
Fe: 27 wt% or less (including 0%),
Pt: 10 ppm or less,
The balance is adjusted so that the composition is substantially composed of oxygen.
These aspects will be specifically described below.

To be treated with platinum group element (referred to as PGM-containing substance), flux component (eg silica, calcium oxide, calcium carbonate, etc.), carbonaceous reducing agent (eg coke powder) and copper source material (copper or copper oxide) Are mixed in an appropriate ratio and charged into an electric furnace. The mixing ratio of the flux components varies depending on the composition of the PGM-containing material, but the composition of the glassy oxide (electric furnace slag) after heating and melting is Al ₂ O ₃ : 20 to 40 wt%, SiO ₂ : 25 to 25%. It is preferable to blend so as to be 35 wt% and CaO: 20 to 35 wt%. The slag oxide produced in the furnace is ultimately determined by the PGM-containing material and the flux component charged into the furnace. This is because the carbonaceous reducing agent does not remain in the slag as an oxide, and substantially all of the copper oxide charged as the copper source material is reduced to metallic copper.

Therefore, in principle, it is possible to determine the composition range of the slag oxide generated in the furnace by the combination of the PGM-containing substance and the flux. However, for this purpose, it is premised that meltdown in the furnace, reduction reaction, slag metal phase separation, etc. are performed well. This precondition is that, as in the above-mentioned aspect 2, all the raw materials charged into the furnace are prepared in the form of powder and granular materials, and these powder and granular materials are mixed in advance and charged into the electric furnace. It turns out that it is satisfied by doing. More specifically, the metal copper or copper oxide charged in the electric furnace preferably has a diameter of 0.1 mm or more and less than 10 mm, and the PGM-containing substance also has a diameter of less than 10 mm by 50 wt%. It is preferable. Then, it is preferable that these are uniformly mixed with the powdery flux and the powdery carbonaceous reducing agent, and the mixed powder is charged into the furnace.

The reducing agent is mainly used to reduce copper oxide to metallic copper. As the reducing agent, coke is typically used, but base metals containing noble metal and PGM can also be used. In this case, the noble metal and PGM in the base metal can be recovered at the same time. Resin, activated carbon, etc. can also be used as a reducing agent. The copper source material is used as a medium in which PGM is dissolved, but metal copper itself may be used, but copper oxide can also be used.

In the electric furnace operation using these charged raw materials, the charged raw materials are first heated and melted (melted down). The temperature for heating and melting is 1200 ° C to 1700 ° C, preferably 1300 ° C to 1550 ° C. If it is less than 1200 degreeC, melting | fusing of slag will not be perfect, but viscosity will also increase and the recovery rate of PGM will fall. However, if the temperature exceeds 1700 ° C., it is not preferable because energy is wasted and the furnace body of the electric furnace is damaged. Due to this meltdown, the PGM support material (alumina and other oxides) that occupies most of the PGM-containing material floats as glassy molten slag, and the copper oxide is reduced by coke to become metallic copper. A metal copper layer (melted metal) is formed which settles and melts in the slag due to the specific gravity difference.

After the charging of the charge in the furnace is completed, the furnace interior is heated and melted by energizing and heating the furnace interior. After this heating and melting, as in the above-mentioned mode 3. , It is preferable to provide a standing step for holding at a temperature of 1200 to 1500 ° C. for at least 5 hours. A standing process of at least 5 hours or more is provided from the slag and meltdown to the discharge of the molten metal. When the charging raw material is a mixture of powdered and granular materials and this standing step is provided, PGM can be taken into the molten metal in the electric furnace containing almost all metallic copper at a high recovery rate.

If the temperature of the standing process is less than 1200 ° C, the recovery rate of PGM is not sufficient even if the standing time is extended, and if it exceeds 1500 ° C, the improvement of the recovery rate of PGM cannot be expected, leading to damage to the furnace. become. Although most of the PGM is recovered by standing at a temperature of 1200 to 1500 ° C. for at least 5 hours, the improvement tendency of the recovery rate reaches saturation even if the standing time is too long. For this reason, it is also thermoeconomic to take a standing time of about 5 to 10 hours and finish the standing step.

The PGM is absorbed by the copper metal in the process of sinking the metal copper into the slag, but the recovery rate of the PGM to the metal copper at this time varies depending on the material temperature after the meltdown and the standing time. Since it varies depending on the particle diameter of the metal copper or copper oxide introduced into the furnace, the particle diameter of the PGM-containing material introduced into the furnace, etc., it is important to appropriately manage as described above.

In this way, according to the present invention, when the stationary process is appropriately managed, and the charged raw materials are mixed as particulates and charged into the furnace, the molten metal in the electric furnace in which most of the metallic copper is contained. PGM can be taken in at a high recovery rate. The reason for this is not clear, but can be considered as follows.

When the carrier material (oxide such as alumina) that occupies most of the PGM-containing material is melted together with the flux, it is dispersed as slag having an appropriate viscosity. The metal copper reduced by slag is also dispersed in the slag, especially when it is mixed as a granular material, the dispersion is good, and the PGM dispersed and suspended in the slag is absorbed, and the weight of the metal copper in the lower layer is reduced. And is absorbed by the metal copper layer. This phenomenon starts from the meltdown, but if the temperature after standing still is low (for example, below 1200 ° C), the viscosity of the slag increases, and the momentum of both PGM and metallic copper in the slag decreases. It will continue to float. On the other hand, if the temperature at the time of standing is too high (for example, exceeding 1500 ° C.), the heating energy is consumed more than necessary, which is uneconomical.

Considering this, in the stationary process, molten metal copper is properly dispersed in the slag having an appropriate viscosity and the PGM is totally dispersed, and at a slow speed. It is important to sink with an appropriate momentum. In order to achieve a good dispersion state, it is necessary to granulate and mix the charged raw materials, and in order to achieve an appropriate viscosity, it is important to add the flux component, adjust the component, and control the temperature. This standing requires sufficient time for substantially all of the molten metallic copper to settle in the slag, so that the reduction of the copper oxide no longer proceeds and the molten metallic copper settles. When finished, the PGM will not be absorbed by the underlying metal melt. According to the method of the present invention that satisfies this condition, PGM can be absorbed into the molten metal with a high recovery rate.

When the stationary process is completed, most of the slag in the furnace can be drained out of the furnace while leaving a part of it. If you want to shorten the operation time, prepare two electric furnaces in parallel, charge the raw material in the second electric furnace and heat and melt it while it is left stationary in the first electric furnace. It is sufficient to carry out. Further, the heated and melted furnace contents can be transferred to another stationary furnace, where the stationary process can be carried out.

Range of component composition of the slag-based oxide produced in the _{furnace, Al 2 O 3: 20~40wt%} , SiO 2: 25~40wt%, CaO: 20~35wt%, FeO: become as 0～35Wt% It is preferable to adjust the raw material composition to this, but this is because the content of each oxide of Al, Si and Fe contained in the PGM-containing material is analyzed and grasped in advance. It is preferable to adjust the flux component composition charged into the furnace accordingly.

More specifically, the PGM-containing substance is pulverized into granular materials of 5 mm or less before being charged into the furnace, and an analytical sample is collected from the pulverized and mixed raw material. By adjusting the analysis value and the flux component (using at least one selected from the group of Al ₂ O ₃ , SiO ₂ , CaO and FeO), the range of the component composition of the slag oxide generated in the furnace is As in aspect 4 above,
Al ₂ O ₃ : 20 to 40 wt%,
SiO _2: 25~40wt%,
CaO: 20 to 35 wt%,
FeO: 0 to 35 wt%
To control.

As a result, the slag oxide separated from the molten metal is, as in the fifth aspect,
Al: 10 to 22 wt%,
Si: 10 to 16 wt%,
Ca: 14-22 wt%,
Fe: 27 wt% or less (including 0%),
Pt: 10 ppm or less,
The balance can be of a component composition consisting essentially of oxygen.

As component composition of the slag-based oxide of the _{Al 2 O 3: 20~40wt%,} SiO 2: 25~40wt%, CaO: 20~35wt%, FeO: If it is 0~35wt%, moderate viscosity In the process of specific gravity separation, the platinum group element mixed in the raw material to be processed is easily absorbed by the molten metal copper. As a result, the final slag at the end of the treatment is, as described above, Al: 10-22 wt%, Si: 10-16 wt%, Ca: 14-22 wt%, Fe: 27 wt% or less (including 0%), Pt: 10 ppm or less, the balance being substantially composed of oxygen.

If the slag generated in the electric furnace is out of the above control range, for example, if Al ₂ O ₃ exceeds 40 wt%, the viscosity of the slag will be extremely increased, and as a result, the molten material reduced from the platinum group elements and copper oxide. The reason for this is thought to be that the contact speed with the metallic copper becomes slow and the molten metallic copper that has absorbed the platinum group element is likely to float in the slag, but the absorption rate of the platinum group element into the molten metal is reduced. To do. A preferable range of Al ₂ O ₃ is 20 to 30 wt%.

After the standing step, most of the upper slag is left outside the furnace while leaving most of it in the furnace and discarded. Next, the molten metal that has absorbed the platinum group element is discharged from the electric furnace and transferred to a furnace that oxidizes in the molten state to concentrate the platinum group element. For this purpose, the molten metal is oxidized with oxygen gas or oxygen-containing gas in an oxidation furnace, and separated into specific gravity differences between an oxide layer composed mainly of copper oxide and a molten metal composed mainly of metallic copper enriched in platinum group elements. To do. The oxidation treatment is performed by introducing an oxygen gas or an oxygen-containing gas while maintaining a temperature of 1100 ° C. to 1600 ° C., preferably 1200 ° C. to 1500 ° C. If the temperature is lower than 1100 ° C, the oxidation rate is low. Conversely, if the temperature exceeds 1600 ° C, the furnace body will be damaged. After the oxidation process, the upper oxide layer is separated from the furnace by tilting the furnace, and then the molten metal enriched with the lower platinum group element is also flowed out of the furnace and sent to the next recovery step.

At the end of this oxidation treatment, after the upper oxide layer is usually discharged, the molten metal that has newly absorbed the platinum group element is received from the electric furnace by the reduced amount, and the remaining molten metal in the furnace. Repeat the oxidation process after making the combined hot water. By repeating this process, the molten metal is discharged from the oxidation furnace only when the content of the platinum group element in the molten metal in the lower layer becomes 10% to 75%, and is sent to the next platinum group element collecting process. Is good.

The oxide layer discharged from the oxidation furnace is mostly copper oxide and can be reused as a copper source material for the electric furnace after flowing out of the furnace and cooling and solidifying. As a result, platinum group elements accompanying the oxide layer can also be recovered. This oxide can be pulverized by rapid water cooling from the molten state, whereby a granular material having a size of 0.1 mm or more and 10 mm or less can be obtained, which is suitable as a raw material charged in an electric furnace. .

[Example 1]
Waste catalyst for purification of automobile exhaust gas containing about 1200 ppm Pt, about 300 ppm Pd and about 90 ppm Rh (average containing about 38.5 wt% Al ₂ O _3, about 39.6 wt% SiO _2, about 12.5 wt% MgO) ) Was crushed to 10 mm or less. To 1000 kg of this granular waste catalyst, 500 kg of CaO as a flux component and 100 kg of SiO ₂ , 30 kg of coke as a reducing agent, and copper oxide (about 80 wt% of granular material of 0.1 mm to 10 mm) 3
00 kg was mixed and charged into an electric furnace.

The used electric furnace has a furnace wall made of a cylindrical iron skin 10 having an outer diameter of about 5 m and a height of about 2.2 m. The material of the iron skin 10 is a carbon steel plate having a thickness of 22 mm. It is what was used. The total amount of water flowing out of the header 12 was 36 m ³ / hr, and the temperature when flowing out of the header 12 was 45 ° C. or less. During operation of the furnace, about 30-50mm inside the iron skin 10
It was estimated that the self-coating layer 14 was formed.

This charge was heated and melted at about 1500 ° C. in an electric furnace. After the meltdown, the material was allowed to stand while being energized so that the material temperature was maintained at about 1400 ° C., and a part of the upper slag was allowed to flow out from the side of the electric furnace every hour to be cooled and solidified. This operation was performed up to 20 hours after the meltdown, and the PGM in the slag collected every hour was analyzed. The analysis results are shown in Table 1.

From the results in Table 1, at this holding temperature, a considerable amount of Pt, Pd and Rh remain in the slag when the standing time is within 5 hours, but when it exceeds 5 hours, it decreases very much, and the tendency is about 8 hours. Can be seen to almost stop.

[Example 2]
Example 1 was repeated except that the holding temperature was 1200 ° C. and the standing time was 5 hours. When PGM in the slag was analyzed in the same manner as in Example 1, as shown in Table 1, Pt: 0.9 pp
m, Pd: 0.2 ppm, Rh: 0.1 ppm or less.

Example 3
Example 1 was repeated except that the holding temperature was 1300 ° C. and the standing time was 5 hours. The PGM in the slag was analyzed in the same manner as in Example 1. As shown in Table 1, Pt: 0.7 pp
m, Pd: 0.1 ppm, Rh: 0.1 ppm or less.

[Comparative Example 1]
Example 1 was repeated except that the holding temperature was 1100 ° C. and the standing time was 5 hours. The PGM in the slag was analyzed in the same manner as in Example 1. As shown in Table 1, Pt: 2.5 ppm, Pd: 0.9 ppm, Rh: 0.2 ppm, and when the holding temperature was less than 1200 ° C.
GM could not be fully transferred from the slag into the metal.

[Comparative Example 2]
Example 1 was repeated except that the holding temperature was 1550 ° C. and the standing time was 5 hours. The PGM in the slag was analyzed in the same manner as in Example 1. As shown in Table 1, Pt: 1.5 ppm, Pd: 0.4 ppm, Rh: 0.1 ppm, and the holding temperature exceeded 1500 ° C. Also, PGM could not be fully transferred from the slag into the metal.

Example 4
At the stage where the treatment was carried out in the same manner as in Example 1 and allowed to stand at 1400 ° C. for 8 hours, the molten metal was tapped from the electric furnace and introduced into a heated oxidation furnace. Oxygen-enriched air with an oxygen concentration of 40% is sprayed onto the molten metal in the oxidation furnace, and when the oxide layer with a thickness of approximately 1 cm is formed on the surface of the molten metal, the furnace is tilted to oxidize the molten metal. The layer of material was discharged from the furnace and put into a water tank in which a large amount of water flowed. Thereafter, the furnace was returned again, and the same oxygen-enriched air was sprayed onto the surface of the molten metal. When the oxide layer reached approximately 1 cm in thickness, the operation of throwing it into the water tank was repeated. By this water cooling, water granulation having a particle size of 10 mm or less was formed. This can be used as copper oxide as part of the raw material for electric furnace charging.

The molten metal in the oxidation furnace after the oxide layer was discharged outside the furnace was added with the molten metal that had undergone the treatment corresponding to Example 2 on the electric furnace side, and the same as described above on the surface of the molten metal. Oxygen-enriched air was blown. Then, when the thickness of the oxide layer reached approximately 1 cm, the operation of discharging out of the oxidation furnace was repeated twice. When the molten metal after treatment was discharged from the oxidation furnace and cooled and solidified, about 10.5 kg of metallic copper was obtained, and the content of PGM in this metallic copper was Pt: about 22 wt.
%, Pd: about 5.5 wt%, and Rh: about 1.5 wt%.

Example 5
1000 kg of spent honeycomb-shaped automobile exhaust gas purification catalyst was put on a conveyor and supplied to a jaw crusher in one stage and a double roll crusher in two stages, and the whole amount was crushed to 5 mm or less. Pass the entire amount of the crushed raw material through two three-stage bifurcaters (1/2 × 1/2 × 1/2 = 1/8), and 15.5 kg of 1/64 representative sample. Collected. The rest of the mother was stored in a silo. After drying the representative sample in its entirety and measuring the moisture content (moisture content = (0.5 wt%)), the whole amount was ground to 100 mesh with a pulverizer, mixed with a V-type mixer, An analytical sample of 100 g was obtained.

When this analysis sample was analyzed with an X-ray fluorescence analyzer, oxides were analyzed.
Al ₂ O ₃ : 40.5 wt%,
SiO ₂ : 41.6 wt%
MgO: 11.5 wt%,
FeO: 1.5 wt%.

The target composition of slag generated in the electric furnace is
Al ₂ O ₃ : 22.3 wt%,
SiO ₂ : 28.5 wt%
CaO: 28.1 wt%,
FeO: 12.1 wt%
Based on the analysis values, 984.5 kg of the base material stored in the silo, and 500 kg of CaO, 100 kg of SiO ₂ and 200 kg of FeO were weighed as flux components so that the target component composition was obtained. Further, 30 kg of coke as a reducing agent and 300 kg of copper oxide (about 80 wt% of powder particles of 0.1 mm to 10 mm) as a copper source material were weighed and all these four materials were mixed.

This mixture was charged into an electric furnace, heated and melted at about 1350 ° C., allowed to stand at a temperature of 1250 to 1300 ° C. for about 5 hours after melting down, and then the upper slag oxide was discharged from the side of the electric furnace. And allowed to cool and solidify. When the platinum group elements in the slag were analyzed, Pt = 0.7 ppm, Pd = 0.1 ppm, and Rh = 0.1 ppm or less, and the loss of the platinum group elements in the slag was very slight.

Moreover, when the oxide component of the slag was analyzed,
Al ₂ O ₃ : 21.5 wt%,
SiO ₂ : 29.2 wt%
CaO: 27.9 wt%,
FeO: 11.8 wt%, and each component was within ± 1.0 wt% of the target component composition.

[Reference Example 1]
Randomly withdrawing 1000 to 15 kg of waste catalyst (converter fragments) of honeycomb type automobile exhaust gas purification of large and small cracked lump in two flexible container bags. The representative sample was completely dried and the moisture content was measured (moisture = 0.8 wt%), and then crushed with a jaw crusher. Crush the crushed material with a pulverizer to 100 mesh or less,
After mixing with a V-type mixer, 100 g of an analytical sample was obtained using a rotary 12-minute device.

When this analytical sample was subjected to a fluorescent X-ray analyzer and analyzed for oxide components,
Al ₂ O ₃ : 37.8 wt%
SiO ₂ : 43.1 wt%,
MgO: 12.3 wt%,
FeO: 1.2 wt%.

The target composition of slag generated in the electric furnace is
Al ₂ O ₃ : 22.0 wt%,
SiO ₂ : 25.1 wt%,
CaO: 29.1 wt%,
FeO: 12.6 wt%,
Based on the analysis value, the used bulk honeycomb-type automobile exhaust gas purification catalyst (converter fragment) = 985 kg, CaO 500 kg, and FeO 200 kg as flux components are weighed to obtain the target component composition. 30 kg of coke and 300 kg of copper oxide (about 80 wt% of 0.1 mm to 10 mm powdered granular material) were charged into an electric furnace and heated and melted at 1350 ° C.

In the electric furnace, the charge is heated and melted at about 1350 ° C., and after standing down at a temperature of 1250 to 1300 ° C. for about 5 hours, the upper slag oxide is allowed to flow out from the side of the electric furnace and cooled. Solidified. When the platinum group element in this slag was analyzed, Pt = 1.8 ppm, Pd = 0.4 ppm, and Rh = 0.2 ppm. Compared with the case of Example 5, the loss of the platinum group element into the slag was Increased.

Moreover, when the oxide component of the slag was analyzed,
Al ₂ O ₃ : 23.5 wt%,
SiO ₂ : 22.1 wt%,
CaO: 29.5 wt%,
FeO: 11.8 wt%. That is, when compared with the value of the target component composition, A
As a result, the contents of l ₂ O ₃ and SiO ₂ were shifted by 1.5% or more.

Example 6
The molten metal containing platinum group elements in the electric furnace after carrying out Example 1 was discharged from the lower part of the electric furnace and led into a heated oxidation furnace. Then, 40% oxygen-enriched air is blown onto the surface of the molten metal in the oxidation furnace to oxidize it, and when the oxide layer formed on the molten surface has a thickness of about 1 cm, the furnace is The oxide was tilted to flow out of the furnace and put into a water tank in which a large amount of water flowed.

Furthermore, oxygen-enriched air was continuously blown into the molten metal in the oxidation furnace, and when the thickness of the oxide grew to about 1 cm, the operation of allowing this to flow out of the furnace and water cooling was repeated. After repeating this operation five times, the platinum group element-containing molten metal in the electric furnace obtained in Comparative Example 1 is led from the lower part of the electric furnace, led into the oxidizing furnace, and combined with the molten metal in the oxidizing furnace. I made hot water. Thereafter, the same oxygen-enriched air was blown into the molten metal in the furnace, and the generated oxide was discharged outside the furnace and water-cooled. The molten metal obtained after the treatment was completely discharged from the oxidation furnace, solidified by cooling, and analyzed. As a result, the metal copper was 5.4 kg, and the platinum group element content was Pt = 21.3 wt%, Pd = 6.7 wt%, Rh = 1.4 wt%
Met.

It is a schematic sectional drawing which shows the principal part of the smelting furnace according to this invention. It is a schematic perspective view which shows the principal part of the furnace wall of the smelting furnace according to this invention. It is a processing system diagram of the cooling water of the smelting furnace according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace interior 2 Electrode 3 Furnace 4 Furnace main body 5 Molten slag layer 6 Metal melt 7 Slag discharge port 8 Metal melt discharge port 9 Material injection chute 10 Iron skin 11 Water film flow 12 Header 13 Annular cage 14 Self-coating layer 15 Nozzle port 16 Storage tank 19 Cooling tower 22 Water head tank

Claims (13)

In a smelting furnace for obtaining a molten metal by reducing an oxide raw material charged in a furnace with a carbonaceous reducing agent, the furnace has a lid and an upper part for substantially shutting off the furnace interior material from the outside atmosphere. A closed electric furnace provided with an electrode for energizing and heating the furnace interior material, and including a furnace wall including a height level of a molten slag layer generated in the furnace. A self-coating layer composed of a solidified layer of the slag is formed in contact with the furnace inner surface of the iron skin, forming a water film flow falling in contact with the outer surface of the iron skin as the outermost peripheral surface. smelting furnace characterized by comprising Te. In a smelting furnace for obtaining a molten metal by reducing an oxide raw material charged in a furnace with a carbonaceous reducing agent, the furnace has a lid and an upper part for substantially shutting off the furnace interior material from the outside atmosphere. A closed electric furnace provided with an electrode for energizing and heating the furnace interior material, and including a furnace wall including a height level of a molten slag layer generated in the furnace. It is composed of an iron skin and is provided with a flange so as to surround the iron skin at the level near the lower end of the molten slag layer and in contact with the outer surface of the iron skin, in contact with the outer surface of the iron skin as the outermost peripheral surface. Solidification of the slag by forming a water film flow descending from a level above the upper end level of the molten slag layer to the level of the soot and in contact with the furnace inner surface including the height level of the molten slag layer of the iron skin be characterized in that the self-coating layer comprising a layer formed by generated Smelting furnace.   The water film flow descending in contact with the outer surface of the iron skin is caused by water of a predetermined head pressure from the header installed on the outer upper part of the furnace wall toward the entire outer circumference of the same level of the iron skin The smelting furnace according to claim 1 or 2, which is formed by being evenly distributed. A molten slag formed in a closed type electric furnace having a lid for substantially blocking the inside of the furnace from the outside atmosphere and an electrode inserted and arranged in the furnace from above and energized and heated. The smelting furnace , which is composed of a steel wall with the furnace wall including the level of the layer, is charged with an oxide raw material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing agent, and a flux. The charge is energized and heated by the electrode and forms a water film flow descending in contact with the outer surface of the iron skin as the outermost peripheral surface, and the charge is melted and reduced to be below the molten slag layer. Forming a self-coating layer comprising a solidified layer of the slag in contact with the furnace inner surface of the iron skin while forming a molten metal layer and concentrating the platinum group element in the molten metal Recovery method for platinum group elements using a furnace. A molten slag formed in a closed type electric furnace having a lid for substantially blocking the inside of the furnace from the outside atmosphere and an electrode inserted and arranged in the furnace from above and energized and heated. A smelting furnace in which a furnace wall including the height level of the layer is made of iron skin, and a slag is installed so as to surround the iron skin at a level near the lower end of the molten slag layer and in contact with the outer surface of the iron skin Into the outer surface of the iron skin , which is charged with an oxide raw material accompanied by a platinum group element, copper oxide, a solid carbonaceous reducing agent and a flux, and these furnace interiors are energized and heated by the electrodes and used as the outermost peripheral surface. Forming a water film flow that is in contact with the surface and descends from a level above the upper end level of the molten slag layer to the level of the soot, and melts and reduces the charge to form a metal melt below the molten slag layer. In this molten metal, a layer of platinum is formed Use the formulation smelting furnace, characterized in that to produce a self-coating layer composed of a solidified layer of the slag in contact with the height level of the molten slag layer of iron skin to encompass furnace inner surface causes the element to the concentrated Recovery method for platinum group elements. Oxide material, copper oxide, prepared in the form of a carbonaceous reducing agent and flux Any particulate matter in the solid, claims these particulate matter is charged into the formulation smelting furnace after having been premixed 4. The method for recovering a platinum group element according to 4 or 5 . After heating and melting of the furnace interior container, after having a standing step of holding at least 5 hours or more to a temperature of 1200 to 1500 ° C., claim to discharge the molten metal of the platinum group element-containing out of the furnace 4 to 6 A method for recovering a platinum group element according to any one of the above. The range of the component composition of the slag-based oxide generated in the furnace is controlled to Al ₂ O ₃ : 20 to 40 wt%, SiO ₂ : 25 to 40 wt%, CaO: 20 to 35 wt%, and FeO: 0 to 35 wt%. The method for recovering a platinum group element according to any one of claims 4 to 7 .   The content of at least one oxide of Al, Si and Fe contained in the oxide raw material accompanied by the platinum group element is analyzed and grasped in advance, and charged into the furnace according to the content of these oxides. The method for recovering a platinum group element according to claim 8, wherein the component composition of the slag oxide is controlled by adjusting a flux component composition to be performed. The method for recovering a platinum group element according to claim 9, wherein the flux contains at least one component selected from the group consisting of Al ₂ O ₃ , SiO ₂ , CaO, and FeO. Slag separated from molten metal
Al: 10 to 22 wt%,
Si: 10 to 16 wt%,
Ca: 14-22 wt%
Fe: 27 wt % or less (including 0 wt %),
Pt: 10 ppm or less,
The method for recovering a platinum group element according to claim 8 or 9, wherein the balance is adjusted so as to have a component composition substantially consisting of oxygen. The molten metal separated from the slag oxide is transferred to another furnace for oxidation treatment, an oxide layer mainly composed of copper oxide, and a molten metal mainly composed of metal copper enriched with platinum group elements, The method for recovering a platinum group element according to claim 4 or 5, wherein the platinum group element is separated by a specific gravity difference. The method for recovering a platinum group element according to claim 4 or 5, wherein the oxide layer mainly composed of copper oxide according to claim 12 is reused as the copper oxide according to claim 4 or 5 .

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