JP2006176830A - Method for concentrating and recovering metallic nickel from powder containing elemental nickel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To concentrate and recover metallic nickel from powder containing nickel element capable of recovering high-purity metallic nickel in powder form without generating a metal bath from powder containing nickel element Provide.
SOLUTION: Powder containing elemental nickel is supplied into a high-temperature reducing gas flow at 500 ° C. or more, causing a reduction reaction in the high-temperature reducing gas stream, and metallic nickel is locally concentrated in the powder. Let
[Selection] Figure 1

Description

  The present invention is a method for concentrating and recovering metallic nickel from a powder containing elemental nickel, and concentrates high-purity metallic nickel with a very low amount of impurities at low cost without generating a metal bath. It relates to the method of recovery.

  Conventionally, many wastes containing nickel elements such as dust and sludge have been discharged from stainless steel factories and plating factories. Some of these are recycled as steelmaking raw materials, but many are still landfilled. The reason why it is difficult to recycle is that impurities such as phosphorus are mixed in the waste, and these impurities are mixed into the product and have an adverse effect.

As a method for obtaining metal from metal oxide-based dust, which is a kind of such waste, powdered metal oxide is supplied into a high-temperature flame from a burner in a reaction furnace, and heated and heated. There has been proposed a method in which a metal is obtained by reducing a molten metal oxide and a reducing agent in a molten metal with a reducing agent that is melted and supplied into a reaction furnace (for example, see Patent Document 1).
JP-A-9-310126

  However, when the method according to Patent Document 1 is used, metal can be obtained from metal oxides contained in dust, sludge, etc., but in order to obtain a metal product as molten steel (molten metal), phosphorus, sulfur, etc. in the metal There is a problem that it becomes difficult to recycle as a steelmaking raw material. Further, in order to maintain a high melting point metal and oxide (slag) melt in the furnace, particularly the refractory in contact with the slag is greatly damaged, so the durability of the furnace body is low and the cost is high. There was also a problem.

  In view of the above-described problems of the prior art, the present invention contains a nickel element that can recover high-purity metallic nickel in powder form from a powder containing nickel element without generating a metal bath. An object is to provide a method for concentrating and recovering metallic nickel from powder.

To solve this problem,
According to the first aspect of the present invention, a powder containing nickel element is supplied into a high-temperature reducing gas stream at 500 ° C. or more, and a reduction reaction is caused in the high-temperature reducing gas stream, and a metal is locally contained in the powder. A method for concentrating and recovering metallic nickel, characterized in that nickel is concentrated.

  The invention according to claim 2 is the method for concentrating and recovering metallic nickel according to claim 1, wherein the high-temperature reducing air stream is a reducing flame air stream generated by a burner.

  The invention according to claim 3 is the method for concentrating and recovering metallic nickel according to claim 2, wherein the powder containing the nickel element is supplied from the burner.

  According to a fourth aspect of the present invention, a mixed fluid in which the nickel element-containing powder and fuel are mixed in advance is ejected from the ejection hole of the burner, and a combustion-supporting gas is ejected from around the mixed fluid. The method for concentrating and recovering metallic nickel according to claim 3, wherein a high-temperature reducing air flow is formed so as to wrap the mixed fluid.

  The invention according to claim 5 is characterized in that the flow rate of the fuel is 40% by volume or more and 95% by volume or less with respect to the flow rate of the combustion-supporting gas sufficient for the fuel to completely burn. This is a method for concentrating and recovering metallic nickel.

  The invention according to claim 6 divides the combustion-supporting gas to be ejected from the periphery of the mixed fluid into two or more systems, and causes the periphery of the mixed fluid to be ejected so as to be wrapped more than twice from the inside to the outside. The method for concentrating and recovering metallic nickel according to claim 4 or 5.

  The invention according to claim 7 is the method for concentrating and recovering metallic nickel according to any one of claims 4 to 6, wherein the combustion-supporting gas ejected from the periphery of the mixed fluid is a swirl flow.

  The invention according to claim 8 is the method for concentrating and recovering metallic nickel according to any one of claims 1 to 7, wherein a solid carbon substance is further added to the high-temperature reducing gas stream.

  The invention according to claim 9 is characterized in that the nickel element-containing powder is at least one selected from the group consisting of steelmaking dust, sludge, waste catalyst, waste, nickel ore, and nickel oxide. The method for concentrating and recovering nickel metal according to claim 8.

According to the method for concentrating and recovering metallic nickel of the present invention, a powder containing nickel element is supplied into a high-temperature reducing gas stream, and the metallic nickel is locally concentrated in the powder to generate a metal bath. Therefore, high-purity nickel metal can be recovered as a powder-treated product.
Further, according to the present invention, high-purity metallic nickel with very few impurities can be produced from waste containing nickel element, and waste can be recycled as a steelmaking raw material.

  Hereinafter, the concentration recovery apparatus for metallic nickel according to the present invention and the method for concentration recovery of metallic nickel from powder containing nickel element will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic block diagram showing an embodiment of a metallic nickel concentration and recovery apparatus according to the present invention, where (a) shows the first embodiment, (b) shows the second embodiment, and (c). These are the schematic diagrams which show 3rd Embodiment.

  As shown in FIG. 1 (a), the metallic nickel concentration recovery apparatus of the present embodiment includes a raw material supply device that supplies a certain amount of powder (raw material powder) containing nickel element to a furnace, and high-temperature reducing gas generation. The apparatus basically includes an apparatus, a furnace, and a dust collector for recovering the generated powder processed product by solid-gas separation of the furnace exhaust gas.

  The powder containing nickel element as the raw material powder is a substance containing a nickel compound in the form of oxides, hydroxides, sulfides, chlorides, etc. or a mixture thereof, and is used in steelmaking and plating processes. Examples include generated dust, sludge, etc., waste such as a waste catalyst containing nickel element, and high purity nickel oxide. Among these, it is preferable that it is at least one selected from the group consisting of steelmaking dust, sludge, waste catalyst, waste, nickel ore, and nickel oxide. Is more preferable. This nickel element-containing powder (raw material powder) may contain other metal elements and impurities such as phosphorus and sulfur as elements other than the nickel element. Among these, the concentration of nickel element is preferably 2% by mass or more, and more preferably 10% by mass or more.

Moreover, when the waste etc. which contain this nickel element are not a powder form, it can apply by performing a grinding | pulverization process. The particle size of the raw material powder is preferably 50 μm or less.
The raw material powder is supplied into a furnace filled with a high-temperature reducing airflow by a raw material supply device. The supply of the raw material powder can be introduced from one place or a plurality of places.

  The high-temperature reducing gas generator is for generating a high-temperature reducing airflow, and the high-temperature reducing airflow is at least one of reducing gases such as carbon monoxide, hydrogen, and hydrocarbons at a high temperature of 500 ° C. or higher. An airflow containing This high-temperature reducing airflow is preferably 1500 ° C. in order to cause a reductive melting reaction in the upper part of the furnace where the raw material powder first contacts, and in the vicinity of the dust collector that collects the powder processed product in the lower part of the furnace In view of preventing the generation of a metal bath, the temperature is preferably 500 to 600 ° C.

  After the raw material powder is supplied into the furnace, it is brought into contact with a high-temperature reducing air flow of 500 ° C. or higher to cause a reduction reaction in the high-temperature reducing air current, and the nickel elements scattered in the raw material powder particles are Concentrates at one or more locations within the particle. By heating and reducing the raw material powder in a high-temperature reducing gas stream, the reduced metallic nickel is melted and concentrated in the particles and spheroidized. Since metallic nickel and other substances are separated in the particles, the obtained powder-treated product has a form in which metallic nickel can be easily separated and recovered.

  The powder processed product obtained by the reduction reaction in the high-temperature reducing airflow is mixed with the exhaust gas and discharged from the furnace, so this is separated into solid and powder and produced by a dust collector such as a bag filter. The treated product (powder containing metallic nickel) is collected. The particle size of the powder-treated product is almost the same as that of the raw material powder, and the melting of nickel occurs only in the particles. Therefore, the raw material powders are not melted and fused to increase the particle size.

  High purity metallic nickel can be obtained by performing the process of separating the powder-treated product enriched with metallic nickel into metallic nickel and other components. Further, the exhaust gas can be reused as a fuel for generating a high-temperature reducing airflow.

According to the method for concentrating and recovering metallic nickel according to the present embodiment, powder containing nickel element is supplied into a high-temperature reducing gas stream, and the temperature inside the furnace is controlled to concentrate metallic nickel locally in the powder. By making it, high-purity metallic nickel can be recovered as a powder-treated product without generating a metal bath.
In addition, according to the method for concentrating and recovering metallic nickel according to the present embodiment, it is possible to produce high-purity metallic nickel with very few impurities at a low cost from waste containing nickel element, etc. Can be recycled.

[Second Embodiment]
As shown in FIG.1 (b), since the metallic nickel concentration collection | recovery apparatus of this embodiment is the same as that of 1st Embodiment except having used the burner instead of the high temperature reducing gas generator, those description is Omitted.

  In this embodiment, a burner is used as the high-temperature reducing gas generator, and the high-temperature reducing airflow is a reducing flame airflow generated by the burner. This reduced flame air flow may be generated by a combustion reaction between the fuel from the burner and the combustion-supporting gas. As this fuel, a gas fuel containing hydrocarbons or a liquid fuel such as kerosene or heavy oil should be used. Can do. As the combustion-supporting gas for burning this fuel, pure oxygen or oxygen-enriched air is used in order to accelerate the reduction reaction by raising the temperature inside the furnace and increasing the partial pressure of carbon monoxide, hydrogen, etc. It is preferable. Further, the fuel and the combustion-supporting gas may be simultaneously supplied into the furnace.

  The flow rate of the combustion-supporting gas is preferably less than an amount sufficient to completely burn the fuel. Specifically, it is preferably 40% by volume or more and 95% by volume or less, and preferably 50% by volume or more and 90% by volume or less with respect to the flow rate of the combustion-supporting gas sufficient for complete combustion of the fuel. More preferred. By setting the flow rate of the combustion-supporting gas to 40% by volume or more and 95% by volume or less, the raw material powder can be heated sufficiently, and the fuel is incompletely burned to generate a high-temperature reducing airflow. A reducing atmosphere can be formed, and the reduction rate of nickel can be improved.

  In the present embodiment, the raw material powder may be supplied from a burner. In order to supply the raw material powder from the burner, the raw material powder is preferably mixed with a carrier gas such as air or nitrogen, and more preferably supplied from the center of the burner. By supplying the raw material powder from the burner, the heating efficiency of the raw material powder can be increased and the reaction time can be shortened.

  FIG. 2 is a cross-sectional view of the tip of a burner of a type that supplies raw material powder from the burner according to this embodiment, and FIG. 4 is a plan view of the tip of the burner according to this embodiment.

The burner 1 shown in FIG. 2 and FIG. 4 is provided in the center part of the burner, the raw material powder flow injection hole 2 by carrier gas, the fuel gas injection hole 3 provided in the circumference | surroundings, and also the circumference | surroundings. The combustion-supporting gas injection hole 4, the piping 5 through which the cooling water flows, and the outermost water-cooling jacket 6 are formed. The fuel gas ejection hole 3 and the combustion-supporting gas ejection hole 4 can be either multi-holes or slit shapes, and these gases are centered on the burner so that the central axis of the ejection hole is wrapped around the raw material powder flow. It is preferable to eject toward the part.
Moreover, the raw material powder flow ejection holes 2 are structured so as to open at a plurality of locations at the tip of the burner instead of at the center of the burner, or to eject the direction of the central axis of the ejection hole toward the outer periphery of the burner. Also good.

[Third Embodiment]
As shown in FIG.1 (c), the metallic nickel concentration collection | recovery apparatus of this embodiment is 2nd Embodiment except ejecting the mixed fluid which mixed the powder and fuel containing nickel element beforehand from a burner. Since they are the same as those described above, description thereof will be omitted.

  In the present embodiment, a mixed fluid in which raw material powder and fuel are mixed in advance is ejected from an ejection hole of a burner, and a combustion-supporting gas is ejected from around the mixed fluid so as to enclose the mixed fluid. It is preferable to form a high-temperature reducing air flow. When the fuel is a gas, it is used as a carrier gas for conveying the raw material powder. When it is a liquid fuel such as kerosene or heavy oil, the raw material powder and the liquid fuel are mixed to form a slurry and supplied to the burner by a pump. There is a way. By mixing the raw material powder and the fuel in advance, the reaction field around the raw material powder becomes a higher temperature reducing atmosphere in the furnace, and the reduction efficiency can be further increased.

  In addition, by using a mixed fluid in which the raw material powder and the fuel are mixed in advance, the atmosphere around the raw material powder can be made strongly reducing when the mixed fluid is reacted with the combustion-supporting gas. . When using a burner, it is preferable to use oxygen-enriched air or pure oxygen as the combustion-supporting gas.

  As a method for supplying the combustion-supporting gas to be ejected from the periphery of the mixed fluid, it is preferable to divide into two or more systems and to eject the mixed fluid so as to wrap around the inside from the inside to the outside. By supplying the combustion-supporting gas in two or more systems, it is easy to control the atmosphere (temperature and gas composition) in the mixed fluid, and in the state of particles in the reaction process in the high-temperature reducing airflow. It is easy to control the required atmosphere.

  Moreover, it is preferable that the combustion-supporting gas ejected from the periphery of the mixed fluid is a swirling flow. By supplying the combustion-supporting gas in a swirling flow, the dispersibility of the powder in the reducing flame stream can be improved, and the heating / reduction reaction can be promoted.

  FIG. 3 is a cross-sectional view of the tip of a burner of a type that supplies a mixed fluid of raw material powder and fuel from the burner according to this embodiment, and FIG. 4 is a plan view of the tip of the burner according to this embodiment. is there.

The burner 1 shown in FIG. 3 and FIG. 4 has a mixed fluid injection hole 20 of a carrier gas and a raw material powder located in the center of the burner, and a primary combustion-supporting gas injection hole provided in the periphery thereof. 41, a secondary combustion-supporting gas injection hole 42 provided in the periphery thereof, a pipe 5 through which cooling water flows, and an outermost water-cooling jacket 6. The primary combustion-supporting gas ejection holes 41 and the secondary combustion-supporting gas ejection holes 42 can be either multi-holes or slit shapes as in the second embodiment, and these gases wrap around the mixed fluid. Moreover, it is preferable to eject the central axis of the ejection hole toward the center of the burner.
By dividing the combustion-supporting gas into a primary system, a secondary system, and two or more systems, and ejecting each of them in an independently controllable state, the heating / reduction reaction can be performed more effectively. By providing vanes in the supply portion of the combustion-supporting gas, or by tilting the central axis of the primary combustion-supporting gas ejection hole in the circumferential direction, the combustion-supporting gas can be ejected as a swirling flow.
When liquid fuel is used as the fuel, the mixed fluid may be sprayed at a high pressure or may be sprayed using compressed air or the like.

  Further, the high-temperature reducing air stream can also be generated using a solid carbon substance such as pulverized coal or coke. In that case, a reducing gas obtained by burning the burner fuel or a separately supplied high-temperature reducing gas can be used. It is preferable to further add a solid carbon material to the reactive gas. By further adding a solid carbon substance into the high-temperature reducing air stream, a stronger reduction reaction can be achieved. This solid carbon substance can be supplied as particles having a particle size larger than the raw material powder in the mixed fluid into the mixed fluid or from the vicinity of the jet outlet of the mixed fluid.

  Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

  As an example of the present invention, the raw material powder and fuel according to the third embodiment shown in FIG. 3 are mixed using the metallic nickel concentration recovery apparatus according to the third embodiment shown in FIG. A case where a burner of a type that supplies fluid from a burner is used is shown.

  The raw material powder was supplied using a table feeder, and LPG was used as a carrier gas. The exhaust gas discharged from the furnace and the obtained powder containing metallic nickel were solid-gas separated by a bag filter, and the powder containing metallic nickel was recovered.

  Table 1 shows the operating conditions. LPG was used as the fuel, and this was used as a carrier gas for supplying raw material powder. Oxygen was used as the combustion-supporting gas. The burner was burned at a supply rate of 40 to 90% with respect to the amount of oxygen required to completely burn the fuel. As the raw material powder, a powder having a particle size of 2 to 200 μm obtained by pre-drying plating sludge was used.

A burner was installed in the upper part of the furnace, and the treated powder containing metallic nickel was collected in the lower part of the furnace.
At this time, the furnace inner wall temperature was about 1500 ° C. in the vicinity of the burner corresponding to the raw material powder input side and about 600 ° C. at the furnace end corresponding to the recovery side of the powder containing metallic nickel. For this reason, a metal bath was not generated at the bottom of the furnace.

  Elemental analysis of the raw material powder was performed with a fluorescent X-ray analyzer. Table 2 shows the elemental analysis values (mass%) of the raw material powder. The nickel element concentration was about 13 to 20% by mass. These nickel forms are mainly nickel hydroxide. Nickel hydroxide changes to nickel oxide when heated. Therefore, in order to obtain metallic nickel, it is necessary to reduce the produced nickel oxide.

  The particle diameter of the processed powder obtained after processing the raw material powder under the operating conditions shown in Table 1 was almost the same as the size of the raw material powder and remained unchanged. About this powder processed material, the ratio of nickel oxide and metallic nickel in the total amount of nickel was analyzed by the bromine methanol method. The chemical analysis values are shown in Table 3. The reduction rate (%) is obtained by dividing the amount of metallic nickel (% by mass) by the total amount of nickel (% by mass). From this result, it was found that the smaller the particle size of the raw material powder, the higher the reduction rate, that is, the metallization rate, and a high reduction rate of 95% or more can be obtained with the raw material powder having a particle size of 2 to 6 μm.

  Next, the processed powder obtained by processing the raw material powder having a particle diameter of 2 to 6 μm was analyzed with a scanning electron microscope (SEM) to obtain an SEM image. 5A and 5B are SEM images of the raw material powder and the processed powder, wherein FIG. 5A is an SEM image of the raw material powder, FIG. 5B is an SEM image of the processed powder, and FIG. 5C is an enlarged powder. It is a SEM image of a processed material. FIG. 5 (c) shows that the nickel metal particles in the powder after the treatment exist as white particles in the raw material particles shown in black. Moreover, it turns out that metallic nickel is contained in the powder after a process in the state isolate | separated completely from other substances.

  Further, when surface analysis was performed (image is not shown), nickel element was distributed almost uniformly in the raw material powder before processing, whereas in the powder after processing, It was found that there was a part where nickel element was concentrated.

  FIG. 6 shows an analysis image of the powder processed product using an electron probe micro analyzer (EPMA). 6A is an SEM image of the processed powder, FIG. 6B is an EPMA analysis image of nickel element performed on the particles at the center of the SEM image, and FIG. 6C is an EPMA analysis of phosphorus element. It is an image. From FIG. 6, it was found that the nickel element contained in the treated powder, that is, metallic nickel particles, contained no phosphorus and distributed around the metallic nickel. Thus, it was found that high-purity metallic nickel was concentrated in the powder after the treatment.

  In this embodiment, nickel hydroxide is used as the form of nickel in the raw material, but nickel hydroxide changes to nickel oxide when ignited. Therefore, even if the form of nickel in the raw material powder is nickel oxide, the same result can be obtained, so that it can be applied to other forms.

  From the above results, according to the present invention, a powder containing nickel element is supplied into a high-temperature reducing gas stream, and the metallic nickel is locally concentrated in the powder without generating a metal bath. It was possible to recover high-purity nickel metal as a powder-treated product.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows one Embodiment of the metallic nickel concentration collection apparatus which concerns on this invention, (a) is 1st Embodiment, (b) is 2nd Embodiment, (c) is 3rd. It is the schematic which shows embodiment. It is sectional drawing of the burner front-end | tip part of the type | mold which supplies the raw material powder which concerns on 2nd Embodiment from a burner. It is sectional drawing of the burner front-end | tip part of the type | mold which supplies the mixed fluid of the raw material powder and fuel which concern on 3rd Embodiment from a burner. It is a top view of the burner tip part concerning the 2nd and 3rd embodiments. It is a SEM image of a raw material powder and a powder processed product, (a) is an SEM image of the raw material powder, (b) is an SEM image of the powder processed product, and (c) is an SEM of an enlarged powder processed product. It is an image. It is the analysis image using the electron probe microanalyzer of a powder processed material, (a) is the SEM image of a powder processed material, (b) is EPMA about the nickel element performed with respect to the particle | grains in the center of a SEM image (C) is an EPMA analysis image of phosphorus element.

Explanation of symbols

1 Burner

Claims (9)

Supplying powder containing nickel element in a high-temperature reducing air flow of 500 ° C. or higher,
A method for concentrating and recovering metallic nickel, characterized in that a reduction reaction is caused in the high-temperature reducing air stream to locally concentrate metallic nickel in the powder.   The method for concentrating and recovering metallic nickel according to claim 1, wherein the high-temperature reducing airflow is a reducing flame airflow generated by a burner.   The method for concentrating and recovering metallic nickel according to claim 2, wherein the powder containing the nickel element is supplied from the burner.   The mixed fluid in which the powder containing the nickel element and the fuel are mixed in advance is ejected from the ejection hole of the burner, and the combustion-supporting gas is ejected from around the mixed fluid, thereby enclosing the mixed fluid. The method for concentrating and recovering nickel metal according to claim 3, wherein a high-temperature reducing air stream is formed as described above.   The method for concentrating and recovering metallic nickel according to claim 4, wherein the flow rate of the fuel is 40% by volume or more and 95% by volume or less with respect to the flow rate of the combustion-supporting gas sufficient for complete combustion of the fuel.   6. The combustion-supporting gas to be ejected from the periphery of the mixed fluid is divided into two or more systems, and the periphery of the mixed fluid is ejected so as to be wrapped in double or more from the inside toward the outside. A method for concentrating and recovering metallic nickel.   The method for concentrating and recovering metallic nickel according to any one of claims 4 to 6, wherein the combustion-supporting gas ejected from the periphery of the mixed fluid is a swirling flow.   The method for concentrating and recovering metallic nickel according to any one of claims 1 to 7, wherein a solid carbon substance is further added to the high-temperature reducing gas stream. The powder containing the nickel element is at least one selected from the group consisting of steelmaking dust, sludge, waste catalyst, waste, nickel ore, and nickel oxide. A method for concentrating and recovering metallic nickel.

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