JPWO2018194165A1 - Metal oxide smelting method - Google Patents

Abstract

For example, in a smelting method in which a metal oxide such as nickel oxide ore containing nickel oxide or the like is used as a raw material and reduced by a carbonaceous reducing agent to obtain a reduced product, a high-quality reduced product can be obtained with high efficiency. Provide a way. Metal oxide smelting method according to the present invention, in a reduction furnace, when reducing the mixture obtained by mixing the metal oxide and carbonaceous reducing agent, alumina, alumina cement, magnesia, magnesia cement, A mixture obtained by mixing a metal oxide and a carbonaceous reducing agent is reduced by heating on a floor covering made of at least one material selected from zirconia, zirconia cement and mullite.

Description

  The present invention relates to a smelting method for metal oxides, for example, a smelting method for obtaining a reduced product by reducing nickel oxide ore or the like with a carbonaceous reducing agent as a raw material.

  As a method of smelting nickel oxide ore called limonite or saprolite, which is a kind of metal oxide ore, a dry smelting method using a smelting furnace to produce nickel matte, a rotary kiln or a moving hearth furnace HPAL which is a dry smelting method for producing ferronickel which is an alloy of iron and nickel, and a wet smelting method for obtaining nickel-cobalt mixed sulfide (mixed sulfide) by adding a high pressure acid leaching sulfide using an autoclave. Processes and the like are known.

  Among the various methods described above, in particular, when smelting by reducing nickel oxide ore using a dry smelting method, the nickel oxide ore as a raw material is crushed to an appropriate size in order to advance the reaction. The process of forming a block is performed as pre-processing.

  Specifically, when the nickel oxide ore is agglomerated, that is, when it is made into a mass from powder or fine particles, the nickel oxide ore is mixed with a reducing agent such as a binder or coke to form a mixture. After further adjusting the water content, the mixture is charged into a lump manufacturing machine, and the lump is called a pellet or a briquette having a size of about 10 mm to 30 mm on one side or about 10 mm to 30 mm (hereinafter, collectively referred to simply as “pellet”). ).

  By the way, the pellets need to have a certain degree of air permeability in order to “fly off” the contained moisture. In addition, if the reduction does not proceed uniformly in the pellet, the composition of the obtained reduced product becomes non-uniform, and inconveniences such as dispersion or uneven distribution of the metal occur. It is important to keep the temperature as uniform as possible when performing the reduction treatment.

  In addition, it is an important technique to coarsen the ferronickel produced by reduction. This is because, when the generated ferronickel has a fine size of, for example, several tens μm to several hundreds μm or less, it is difficult to physically separate the slag from the simultaneously generated slag, and the recovery rate (yield) as ferronickel ) Is greatly reduced.

  Also, how to keep the smelting cost low is an important technical matter, and continuous processing that can be operated with compact equipment is desired.

  For example, in Patent Document 1, an agglomerate containing iron oxide as a metal oxide and a carbonaceous reducing agent is supplied to the hearth of a moving bed type reduction melting furnace, heated, reduced and melted, and the resulting granular material is obtained. In the method of cooling and discharging the metal to the outside of the furnace to recover the iron oxide in the agglomerate, the furnace temperature in the first half region of the furnace for solid reduction of iron oxide is 1300 to 1450 ° C., and the reduced iron in the agglomerate is When the furnace temperature in the second half of the furnace to be carburized, melted and agglomerated is set to 1400 to 1550 ° C. and the distance between the agglomerates spread on the hearth is set to 0, the maximum For the projected area ratio, when the relative value of the projected area ratio of the agglomerate spread on the hearth to the hearth is defined as the floor density, the floor density of the agglomerate on the hearth is 0.5 or more and 0.8 or less. When heating, the average diameter is 19.5 mm or more and 32 mm or less A method of supplying Narubutsu the hearth is disclosed.

  According to such a method of Patent Document 1, it is described that the productivity of granular metallic iron can be improved by controlling together with the bed density and average diameter of the agglomerate. As disclosed in Patent Document 1, by controlling the bed density and average diameter of the agglomerate, the productivity of granular metallic iron can be improved. However, Patent Document 1 is a technique relating to a reaction on the outer surface of agglomerates. On the other hand, the reduction reaction is a reaction inside the agglomerate. Therefore, it is difficult to control the reduction reaction in the agglomerate by the method of Patent Document 1.

  Further, when the diameter of the agglomerate is limited to a predetermined range as in Patent Document 1, there is a problem that the yield at the time of producing the agglomerate decreases and the cost increases. Further, when the bed density of the agglomerate is in the range of 0.5 or more and 0.8 or less, the efficiency is low because the agglomerate is not in the most densely packed state and the agglomerate is not stacked. Furthermore, in the case of using a moving hearth furnace as disclosed in Patent Document 1, since the operation is performed continuously, it is also important to always maintain the state of the furnace stably.

  Further, in a process using a so-called total melting method in which all raw materials are melted and reduced as in Patent Document 1, there is a large problem in terms of operating costs. For example, in order to completely melt the above-mentioned nickel oxide ore, it is necessary to heat it to a high temperature of 1500 ° C. or more. Obtaining such a high temperature requires enormous energy costs, and the furnace used at such a high temperature is easily damaged, so that the repair cost also increases. The target nickel contains only about 1% of nickel oxide ore as a raw material. Therefore, although it is not necessary to recover the iron component in an amount exceeding the stoichiometric amount necessary to form ferronickel by reacting with nickel, it is necessary to melt all of the components that do not need to be recovered in a large amount. And is extremely inefficient.

  For this reason, only the necessary nickel is reduced preferentially, and the reduction of iron contained in a much larger amount than nickel is only partially performed. The reduction method by partial melting ("partial reduction method", or nickel preferential reduction method) Law) has been considered.

  However, in such a partial reduction method, since the raw material is not completely melted and the reduction reaction is performed while maintaining it in a semi-solid state, nickel is reduced 100% completely while reducing iron very little. It is not easy to control the reaction so that only the parts are kept. For this reason, there was partial variation in the reduction in the raw material, and it was difficult to efficiently operate such as a reduction in the nickel recovery rate.

  By the way, in a reduction furnace which performs a reaction at a high temperature, its material is a problem. Normal fixed-bed furnaces have a structure in which refractory bricks are placed on a frame made of cast iron or the like.However, in a rotary hearth furnace, the hearth and furnace walls are In many cases, a light weight thin structure is adopted. In such a case, a hearth material (also referred to as "floor material") is laid on the hearth to protect the hearth from reaction between the processed material and the hearth and from the burning of the processed material on the hearth. Measures have been taken.

  Conventionally, it has been common to use coal, coke, or the like as the floor covering material. Since these also act as reducing agents at the same time, they are not suitable when it is necessary to accurately control and maintain the reducing state in the furnace. In addition, at high temperatures, there is also a problem that the reaction as a floor covering material disappears due to the reaction with the atmospheric gas or the processed material, making it difficult to repeatedly use the material and increasing the cost.

  As described above, it is not easy to reduce the metal oxide with high efficiency and obtain a high-quality reduced product.

JP 2011-256414 A

  The present invention has been proposed in view of such circumstances. For example, a metal oxide such as nickel oxide ore containing nickel oxide or the like is used as a raw material and reduced by a carbonaceous reducing agent to obtain a reduced product. In a smelting method, a method capable of obtaining a high-quality reduced product with high efficiency is provided.

  The present inventors have intensively studied to solve the above-mentioned problem. As a result, using a specific floor covering material or laying the floor covering material in a specific arrangement on the hearth, reducing the metal oxide with a carbonaceous reducing agent on the floor covering material to obtain a reduced product As a result, it has been found that a smelting process can be performed efficiently, and the present invention has been completed. Specifically, the present invention provides the following.

  (1) A first invention of the present invention relates to a method for smelting a metal oxide which reduces a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, comprising: A metal oxide smelting method in which the mixture is heated and reduced on a floor covering made of at least one material selected from alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. .

(2) In the second invention of the present invention, in the first invention, the floor covering material is composed of particles of the material (floor covering particles), and is obtained by the following equations (1) and (2). A metal oxide smelting method in which the average floor covering material volume ratio is 3% or more and 85% or less.
Average floor covering volume ratio = sum of floor covering material volume ratios of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere whose diameter is the maximum particle length of floor covering particles) × 100 (2)

(3) In the third aspect of the present invention, in the first or second aspect, the floor covering material is composed of particles of the material (floor covering particles), and an average obtained by the following equation (3). This is a method for smelting a metal oxide having a maximum particle length of 10 μm or more and 6000 μm or less.
Average maximum particle length = sum of maximum particle length of 300 floor covering material particles / 300 (3)

(4) A fourth invention of the present invention relates to a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, comprising: Is not less than 0.001 μm ^{−1 and not} more than 3.0 μm ⁻¹ and the average maximum particle length is 15.0 μm or more and not more than 2000 μm or less (floor bedding material particles). This is a method for refining metal oxides by heating and reducing.

  (5) The fifth invention of the present invention is the fourth invention, wherein the floor covering material particles are at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. This is a method for smelting metal oxides.

(6) The sixth invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, wherein A floor bedding material is laid on the hearth of the furnace, and the floor bedding material is composed of particles (floor material particles), and the number of floor bedding material particles having a maximum particle length of 50.0 μm or less contained in the floor bedding material is as follows: It is 1% or more and 40% or less with respect to the total number of floor covering material particles contained in the floor covering material, and the floor covering material particles have an average maximum particle length determined by the following formula (3) of 40.0 μm to 1050 μm. The following is a method for refining a metal oxide.
Average maximum particle length = sum of maximum particle length of 300 floor covering material particles / 300 (3)

(7) A seventh invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
Laying a floor covering material on the hearth of the reduction furnace,
A metal oxide smelting method in which the mixture is arranged and heated and reduced on the floor covering so that the area of the hearth when viewed from above is 50% or less of the area of the hearth.

  (8) The eighth invention of the present invention is the metal oxide smelting method according to the seventh invention, wherein the mixture has a spherical, cubic, or rectangular parallelepiped shape.

  (9) A ninth invention of the present invention is the metal oxide smelting method according to any one of the first to eighth inventions, wherein the reduction temperature is 1200 ° C to 1450 ° C.

  (10) The tenth invention of the present invention is the method for refining a metal oxide according to any one of the first to ninth inventions, wherein the metal oxide is a nickel oxide ore.

  (11) An eleventh invention of the present invention is the method for refining a metal oxide according to any one of the first to tenth inventions, wherein the reduced product contains ferronickel.

  According to the present invention, for example, in a smelting method in which a metal oxide such as nickel oxide ore containing nickel oxide or the like is used as a raw material and is reduced with a carbonaceous reducing agent to obtain a reduced product, a high-quality reduced product is produced. It can be obtained with efficiency.

It is a flowchart showing an example of a flow of a smelting method of nickel oxide ore. It is a process showing a process performed in the reduction process. It is a figure (top view) showing the example of composition of the rotary hearth furnace with which a hearth rotates. FIG. 2 is a schematic view of an irregular particle and a sphere having a maximum particle length as a diameter. It is a schematic diagram which shows the maximum particle length of an irregular-shaped particle. It is a schematic diagram which shows the example of installation of the spherical mixture with respect to a floor covering material. It is a schematic diagram which shows the example of installation of a rectangular parallelepiped mixture with respect to a floor covering material.

≪1. Outline of the present invention≫
The metal oxide smelting method according to the present invention is a smelting method in which a metal oxide is used as a raw material and a reduction treatment is performed at a high temperature with a carbonaceous reducing agent to obtain a reduced product. For example, as a metal oxide, a nickel oxide ore containing nickel oxide, iron oxide, or the like is used as a raw material, and nickel is given priority to the smelting raw material at a high temperature by a carbonaceous reducing agent, and iron is partially removed. To produce ferronickel by reducing to

Specifically, this metal oxide smelting method uses a specific floor covering material, or lays a floor covering material in a specific arrangement on a hearth, and converts the metal oxide onto a carbonaceous material on the floor covering material. It is characterized by being reduced by a reducing agent, and has four specific embodiments. In the first aspect, a metal oxide and a carbonaceous reducing agent are formed on a floor covering made of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. And reducing the resulting mixture. In the second aspect, metal on a floor covering material composed of particles having a specific surface area of not less than 0.001 μm ^{−1 and not} more than 3.0 μm ⁻¹ and an average maximum particle length of not less than 15.0 μm and not more than 2000 μm. It is characterized in that a mixture obtained by mixing an oxide and a carbonaceous reducing agent is reduced. In the third aspect, when a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent is reduced in a reduction furnace, floor covering material particles composed of particles and having a maximum particle length of 50.0 μm or less are used. Is 1% or more and 40% or less with respect to the total number of particles of the floor covering material contained in the floor covering material, and the average maximum particle length is 40.0 μm or more and 1050 μm or less. I do. In the fourth aspect, in reducing the mixture obtained by mixing the metal oxide and the carbonaceous reducing agent in the reduction furnace, the metal oxide is reduced with the carbonaceous reducing agent in the former furnace. In the smelting process to obtain the reduced product, a floor covering material is laid on the hearth of the reduction furnace, and the mixture is placed on the floor covering material so that the area becomes 50% or less of the area of the hearth when the hearth is viewed in plan. It is characterized by placing and reducing.

  According to such a smelting method, the metal contained in the metal oxide can be effectively metallized, and an efficient smelting process can be performed.

  Hereinafter, as a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”), a smelting method of a nickel oxide ore will be described as an example. Nickel oxide ore, which is a smelting raw material, contains at least nickel oxide. In this method for smelting nickel oxide ore, ferronickel (iron-nickel alloy) is reduced by reducing nickel oxide and the like contained in the raw material. Can be manufactured.

  The present invention is not limited to a nickel oxide ore as a metal oxide, and the smelting method is not limited to a method of producing ferronickel from a nickel oxide ore containing nickel oxide or the like. Various changes can be made without changing the gist of the present invention.

{2. Nickel oxide ore smelting method≫
The method for smelting nickel oxide ore according to the present embodiment comprises mixing nickel oxide ore, which is a smelting raw material, with a carbonaceous reducing agent, kneading the mixture to form a mixture, and subjecting the mixture to a reduction treatment. In this method, ferronickel, which is a metal, and slag are produced as reductants. Note that ferronickel, which is a metal, can be recovered by separating the metal from a mixture containing the metal and slag obtained through the reduction treatment.

  FIG. 1 is a process chart showing an example of a flow of a method for smelting nickel oxide ore. As shown in FIG. 1, this method for smelting nickel oxide ore includes a mixing treatment step S1 of mixing nickel oxide ore and a material such as a carbonaceous reducing agent to obtain a mixture, and aggregating or mixing the obtained mixture. A pre-reduction charge treatment step S2 for filling and molding into a predetermined container, a reduction treatment step S3 for reducing the mixture at a predetermined temperature (reduction temperature), and a step of reducing the metal from the mixture containing the metal and slag generated by the reduction processing. And a separation step S4 for separating and collecting.

<2-1. Mixing process>
The mixing step S1 is a step of mixing a raw material powder containing nickel oxide ore to obtain a mixture. Specifically, in the mixing treatment step S1, nickel oxide ore as a smelting raw material, an iron source such as iron ore, a flux component, a binder, a carbonaceous reducing agent, and the like, for example, have a particle size of 0.1 mm to 0.8 mm. The raw material powder is mixed at a predetermined ratio to obtain a mixture.

  The nickel oxide ore that is the ore of the smelting raw material is not particularly limited, but limonite ore, saprolite ore, or the like can be used.

  The iron source supplies the iron necessary to react with nickel in the nickel oxide ore to form ferronickel. As the iron source, for example, iron ore having an iron grade of about 50% or more, hematite obtained by hydrometallurgy of nickel oxide ore, or the like can be used.

  Table 1 below shows an example of the composition (% by weight) of the nickel oxide ore, which is the raw material, and the iron ore. The composition of the raw material is not limited to this.

  Examples of the binder include bentonite, polysaccharide, resin, water glass, dehydrated cake, and the like. Examples of the flux component include calcium oxide, calcium hydroxide, calcium carbonate, and silicon dioxide.

  Although it does not specifically limit as a carbonaceous reducing agent, For example, coal powder, coke, etc. are mentioned. In addition, it is preferable that this carbonaceous reducing agent has a size equivalent to the particle size of the nickel oxide ore of the raw material ore. Further, as the mixing amount of the carbonaceous reducing agent, for example, the chemical equivalent required to reduce the total amount of nickel oxide contained in the formed mixture to nickel metal, and the ferric oxide contained in the pellets as a metal When the total value of the chemical equivalents required for reducing iron and the total value thereof (for convenience, also referred to as the "total value of chemical equivalents") is 100%, the carbon amount is preferably 5% by mass or more and 60% by mass or less. , More preferably 10% by mass or more and 40% by mass or less.

  When the amount of the carbonaceous reducing agent is 5% by mass or more with respect to the total chemical equivalent of 100%, the reducibility of nickel can be further increased, and the productivity can be increased. On the other hand, by controlling the carbon content to 60% by mass or less, it is possible to suppress the reduction reaction from proceeding excessively, and to suppress an increase in the amount of reduction of iron and a decrease in nickel quality in ferronickel accompanying the reduction. The quality in the obtained ferronickel alloy can be further enhanced. As described above, by setting the ratio of the carbon amount to 5% by mass or more and 60% by mass or less, a shell (metal shell) generated by the metal component can be uniformly formed on the surface of the raw material formed into a pellet or the like. More preferable in terms of productivity, quality and quality.

  The “pellet” refers to a lump obtained by molding a mixture obtained by mixing at least the oxide ore and the carbonaceous reducing agent, and may be simply referred to as a “mixture”.

  In the mixing step S1, a mixture is obtained by uniformly mixing the raw material powders containing nickel oxide ore as described above. In this mixing, kneading may be performed simultaneously, or kneading may be performed after mixing. As described above, by mixing and kneading the raw material powders, the contact area between the raw materials is increased, and the voids are reduced, so that the reduction reaction easily occurs and the reaction can be uniformly performed. Thereby, the reaction time of the reduction reaction can be shortened, and there is no variation in quality. As a result, a highly productive treatment can be performed, and high quality ferronickel can be produced.

  After kneading the raw material powder, the mixture may be extruded using an extruder. By extruding with an extruder in this manner, a higher kneading effect can be obtained, the contact area between the raw material powders can be increased, and the gap can be reduced. Thereby, high quality ferronickel can be efficiently produced.

<2-2. Pretreatment process for reduction input (pretreatment process)>
The reduction charging pretreatment step S2 is a step of agglomerating the mixture obtained in the mixing processing step S1 into a lump, or filling the mixture into a container and molding. That is, in the reduction charging pretreatment step S2, the mixture obtained by mixing the raw material powders is easily introduced into the furnace used in the reduction processing step S3 described below so that the reduction reaction occurs efficiently. Molding.

(Agglomeration of mixture)
When agglomerating the obtained mixture, the mixture is molded (granulated) into a lump. Specifically, a predetermined amount of water required for agglomeration is added to the obtained mixture, and for example, an agglomerate manufacturing apparatus (rolling granulator, compression molding machine, extrusion molding machine, etc., also referred to as a “pelletizer”). ) And the like (hereinafter, also referred to as “pellet”).

  The shape of the pellet is not particularly limited, and may be spherical, cubic, rectangular, or the like. For example, spherical pellets are preferable because the reduction reaction easily proceeds relatively uniformly. Further, since the pellets are cubic or rectangular, the pellets can be stably placed on the floor covering material laid on the hearth, and the handling property is improved.

  The size of the mass to be formed into pellets is not particularly limited. For example, in order to perform a reduction process (reduction process S33) through a drying process (drying process S31) and a pre-heat treatment (preheating process S32). The size (diameter in the case of a spherical pellet) of a pellet to be charged into a smelting furnace or the like to be used can be about 10 mm to 30 mm. The reduction step and the like will be described later in detail.

(Filling the mixture into a container)
When the obtained mixture is filled into a container and molded, the mixture can be filled into a predetermined container while being kneaded with an extruder or the like. It is preferable that the mixture filled in the container is compacted by a press or the like. The mixture is compacted and molded in a container, taken out of the container and subjected to the subsequent reduction treatment step S3, whereby the density of the mixture can be increased, and the density can be made uniform, so that the reduction reaction can proceed more uniformly. Thus, ferronickel with small quality variation can be manufactured.

  The shape of the mixture to be filled in the container is not particularly limited, but is preferably, for example, spherical, rectangular, cubic, cylindrical, or the like. Also, the size is not particularly limited. For example, if the size is spherical, the diameter is preferably about 500 mm or less. Further, for example, in the case of a rectangular parallelepiped shape or a cubic shape, it is preferable that the vertical and horizontal inner dimensions are generally 500 mm or less. By adopting such a shape and size, smelting with a small variation in quality and high productivity can be performed.

<2-3. Reduction process>
In the reduction processing step S3, for example, the mixture obtained by mixing the raw material powders in the mixing processing step S1 and agglomerating in the reduction input pretreatment step S2, or the mixture filled and molded into a container is subjected to a predetermined process in a reduction furnace. Is reduced and heated at the reduction temperature. Then, by the reduction heat treatment of the mixture in the reduction treatment step S3, the smelting reaction proceeds, and metal and slag are generated.

  Here, at the time of the heat reduction, a material composed of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite is used as the floor covering material. By spreading such a floor covering material on the hearth of the reduction furnace, placing the mixture on the floor covering material and reducing by heating, it is possible to suppress a direct reaction between the mixture and the hearth of the reduction furnace. it can. In addition, by using a floor covering material of the type described above, a reaction with the mixture can be suppressed, and high-quality ferronickel can be manufactured. Since the reaction with the mixture is suppressed, the floor covering material can be reused, and the smelting cost can be reduced.

  FIG. 2 is a process chart showing the processing steps executed in the reduction processing step S3. As shown in FIG. 2, the reduction treatment step S3 includes a drying step S31 for drying the mixture, a preheating step S32 for preheating the dried mixture, a reduction step S33 for reducing the mixture, and cooling the obtained reduced product. And a cooling step S35. Further, a temperature holding step S34 for holding the reduced product obtained through the reduction step S33 in a predetermined temperature range is provided.

  Here, the processing in the reduction step S33 is performed using a reduction furnace. As the reduction furnace, for example, a movable hearth furnace or a rotary hearth furnace can be used. Further, when performing the temperature holding step S34 for holding the reduced product in a predetermined temperature range, at least the processing in the reduction step S33 and the processing in the temperature holding step S34 are performed in one reduction furnace.

  Thus, by performing these processes in one reduction furnace, the temperature in the reduction furnace can be maintained at a high temperature, so that the temperature is raised or lowered with each process in each process. This eliminates the necessity of performing such operations, thereby reducing energy costs. From this, it is possible to continuously and stably produce high quality ferronickel with high productivity.

(1) Drying Step In the drying step S31, the mixture obtained by mixing the raw material powders is subjected to a drying treatment. The purpose of the drying step S31 is to mainly remove water and crystal water in the mixture.

  The mixture obtained in the mixing process step S1 contains a large amount of moisture and the like, and in such a state, when rapidly heated to a high temperature such as the reduction temperature during the reduction process, the moisture was vaporized, expanded, and agglomerated at once. The mixture is cracked and, in some cases, ruptured and shattered, making it difficult to perform a uniform reduction treatment. Therefore, prior to performing the reduction treatment, the mixture is subjected to a drying treatment to remove water, thereby preventing the destruction of pellets and the like.

  The drying process in the drying step S31 is preferably performed in a form connected to a reduction furnace. It is conceivable to provide an area (drying area) for performing the drying process in the reduction furnace, but in such a case, the drying process in the drying area is rate-determining, and the processing in the reduction step S33 and the temperature holding step are performed. This may affect the processing in S34.

  Therefore, the drying process in the drying step S31 is preferably provided outside the furnace of the reduction furnace, and is preferably performed in a drying chamber connected to the reduction furnace. As will be described in detail later, FIG. 3 shows a configuration example of a rotary hearth furnace 1 which is an example of a reduction furnace, and a drying chamber 20 connected to the rotary hearth furnace 1. As described above, by providing the drying chamber 20 outside the rotary hearth furnace 1, a drying chamber can be designed completely separately from the steps of preheating, reduction, and cooling described below, and desirable drying processing, preheating treatment, reduction processing, It becomes easier to execute the respective cooling processes. For example, when a large amount of moisture remains in the mixture depending on the raw material, the drying process takes a long time, and therefore, the entire length of the drying chamber 20 may be designed to be longer, or the mixture in the drying chamber 20 may be used. What is necessary is just to design so that a conveyance speed may become slow.

  The drying process in the drying chamber 20 can be performed, for example, so that the solid content in the mixture is about 70% by weight and the water content is about 30% by weight. The drying method is not particularly limited, but can be performed by blowing hot air on the mixture conveyed in the drying chamber 20. Also, the drying temperature is not particularly limited, but is preferably 500 ° C. or lower, and preferably uniformly dried at the temperature of 500 ° C. or lower, from the viewpoint of preventing the reduction reaction from starting.

  Table 2 below shows an example of the composition (parts by weight) of the solid content in the mixture after the drying treatment. The composition of the mixture is not limited to this.

(2) Preheating Step In the preheating step S32, the mixture from which moisture has been removed by the drying treatment in the drying step S31 is preheated (preheating).

  When the mixture is charged into a reduction furnace and suddenly heated to a high reduction temperature, the mixture may be cracked or powdered due to thermal stress. In addition, the temperature of the mixture does not rise uniformly, causing a variation in the reduction reaction, and the quality of the produced metal may vary. Therefore, after the mixture is subjected to the drying treatment, it is preferable to preheat the mixture to a predetermined temperature, whereby the destruction of the mixture and the variation in the reduction reaction can be suppressed.

  The preheat treatment in the preheating step S32 is preferably performed in a processing chamber provided outside the furnace of the reduction furnace, similarly to the drying processing, and is performed in a preheating chamber connected to the reduction furnace. Is preferred. FIG. 3 shows an example of the configuration of a preheating chamber 30 connected to the rotary hearth furnace 1 as an example of a reduction furnace. The preheating chamber 30 is provided outside the rotary hearth furnace 1. It is provided continuously from a drying chamber 20 for performing a drying process. As described above, by performing the pre-heat treatment in the preheating chamber 30 provided outside the furnace of the rotary hearth furnace 1, the temperature in the rotary hearth furnace 1 for performing the reduction process can be maintained at a high temperature, Energy required for reheating the inside of the floor furnace 1 can be significantly reduced.

  The pre-heat treatment in the pre-heating chamber 30 is not particularly limited, but is preferably performed at a pre-heating temperature of 600 ° C or higher, and more preferably at a pre-heating temperature of 700 ° C. or higher and 1280 ° C. or lower. By performing the treatment at a preheating temperature in such a range, the energy required for reheating to the reduction temperature in the subsequent reduction treatment can be significantly reduced.

(3) Reduction Step In the reduction step S33, the mixture preheated in the preheating step S32 is reduced at a predetermined reduction temperature. The reduction treatment in the reduction step S33 can be performed using a reduction furnace such as a movable hearth furnace or a rotary hearth furnace. Then, a floor covering material is placed on the hearth of this reduction furnace, and a mixture of nickel oxide ore and a carbonaceous reducing agent is placed on the floor covering material. As described above, there are four specific embodiments of the reduction. Hereinafter, each embodiment will be described.

(3-1) Reduction Step of First Aspect In the reduction step of the first aspect, at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite as a floor covering material And a mixture of nickel oxide ore and a carbonaceous reducing agent is placed on the floor of the reduction furnace to reduce nickel oxide ore.

  In this way, the specific floor covering material is placed on the hearth of the reduction furnace, and the mixture is placed on the floor covering material and subjected to the reduction treatment, whereby the reaction between the mixture and the hearth, The reaction with the floor covering material can be suppressed, and high-quality ferronickel can be manufactured. Further, the obtained reduced product can be effectively recovered. Further, by reusing the floor covering material, the cost of smelting can be reduced.

  Although the shape of the floor covering material is not particularly limited, it is preferable to use, for example, a material composed of particles (floor covering material particles). By composing the floor bedding material with the floor bedding particles, the contact area between the mixture and the floor bedding material becomes appropriate, and the operability when laying down on the hearth and the handling when collecting from the hearth Also excellent. If the contact area between the mixture and the floor covering material is too large, the reaction between the mixture and the floor covering material may proceed. On the other hand, if the contact area is too small, the generated slag or metal may permeate into the gap between the floor coverings.

  When a material composed of particles is used as the floor covering material, the average floor covering material volume ratio is, for example, preferably 3% or more, more preferably 4% or more, and more preferably 5% or more. More preferably, On the other hand, the average floor covering material volume ratio is preferably 85% or less, more preferably 82% or less, even more preferably 80% or less. By using the floor covering material having an average floor covering volume ratio in such a range, the contact area between the mixture and the floor covering material becomes more appropriate.

Here, in the first aspect, the “average floor covering material volume ratio” is an average value of the volume ratio (floor floor covering material volume ratio) of arbitrary 300 floor covering material particles, and is expressed by the following formula (1). Desired. The “floor material volume ratio” is a ratio of the volume of the bedding material when the volume of a sphere having a diameter of the maximum particle length of the bedding material is 100%, and the following formula (2) Required by
Average floor covering volume ratio = sum of floor covering material volume ratios of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere whose diameter is the maximum particle length of floor covering particles) × 100 (2)

  In the first embodiment, the “maximum particle length” in the above formula (2) refers to the longest diameter or side of a specific particle. Specifically, if the particles are elliptical, the maximum particle length is a long diameter, and if the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. Therefore, in the first embodiment, the “sphere having a diameter equal to the maximum particle length of the floor covering particles” refers to a sphere that is in contact with the floor covering particles and includes the floor covering particles.

  FIG. 4 is a schematic diagram of an amorphous particle and a sphere having a maximum particle length as a diameter. In the case of irregular particles, the maximum particle length is determined as shown in FIG. In the first embodiment, the “maximum particle length” can be measured using a metallographic microscope. On the other hand, the volume of the floor covering material particles can be calculated by measuring the weight since the density of the floor covering material is known. In this way, 300 floor covering material particles selected at random are measured, the floor covering material volume ratio is obtained, and the average floor covering material volume ratio is calculated by equation (1).

  When a material composed of particles is used as the floor covering material, the size of the floor covering material particles is not particularly limited, but the average maximum particle length is preferably 10 μm or more, and more preferably 15 μm or more. It is more preferably at least 20 μm. On the other hand, the average maximum particle length is preferably 6000 μm or less, more preferably 5500 μm or less, and still more preferably 5000 μm or less. When the floor covering material has the average maximum particle length in such a range, the contact area between the mixture placed on the floor covering material and the floor covering material becomes appropriate.

Here, in the first embodiment, the “average maximum particle length” refers to the average maximum particle length of 300 floor covering material particles selected at random, and is obtained by the following equation (3).
Average maximum particle length = sum of maximum particle lengths of 300 floor covering materials / 300 (3)

As bedding material, if used those composed of particles, the specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, 0.002 .mu.m ^-1 or Is more preferable, and more preferably 0.003 μm ⁻¹ or more. On the other hand, the specific surface area is, for example, preferably 3.0 μm ⁻¹ or less, more preferably 2.5 μm ⁻¹ or less, and still more preferably 2.0 μm ⁻¹ or less. By using a floor covering material having a specific surface area in such a range, the contact area between the mixture and the floor covering material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring device.

  Although the arrangement ratio of the mixture to the hearth is not particularly limited, for example, it is preferable to arrange the mixture so as to be 1% or more of the area of the hearth when the hearth is viewed in plan, and 1.5% It is more preferable to arrange the mixture so as to be as described above, and it is further preferable to arrange the mixture so as to be 2% or more. On the other hand, the arrangement ratio of the mixture with respect to the hearth is preferably such that the mixture is 50% or less of the area of the hearth, more preferably 45% or less. %, And more preferably, the mixture is 40% or less.

(3-2) Reduction Step of Second Embodiment In the reduction step of the second embodiment, the specific surface area is 0.001 μm ^{−1 to} 3.0 μm ⁻¹ , and the average maximum particle length is 15.0 μm to 2000 μm. The following bedding material (floor material particles) is placed on the hearth of a reduction furnace, and a mixture of nickel oxide ore and a carbonaceous reducing agent is placed on the floor material to reduce nickel oxide ore. I do.

  In this way, the specific bedding material particles are placed on the hearth of the reduction furnace, and the mixture is placed on the bedding material and subjected to the reduction treatment, whereby the reaction between the mixture and the hearth and the mixture are performed. The reaction with the floor covering material can be suppressed, and high-quality ferronickel can be manufactured and can be effectively recovered. Also, by reusing floor coverings, smelting costs can be reduced.

Here, as the floor covering material, a material composed of particles is used. Then, the bedding material particles, the specific surface area is at 0.001 [mu] m ^-1 or more 3.0 [mu] m ^-1 or less, and an average maximum particle length is less 2000μm or more 15.0 .mu.m. By using a floor covering material composed of particles and having a specific surface area and an average maximum particle length in such a range, the contact area between the mixture and the floor covering material becomes appropriate. If the contact area between the mixture and the floor covering material is too large, the reaction between the two may proceed. On the other hand, if the contact area is too small, the generated slag or metal may permeate into the gap between the floor coverings. The “specific surface area” can be measured using a general specific surface area measuring device.

  In the second embodiment, “maximum particle length” refers to the longest diameter or side of a specific particle. Specifically, if the particles are elliptical, the maximum particle length is a long diameter, and if the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. FIG. 5 is a schematic diagram showing the maximum particle length of the irregular-shaped particles. In the case of irregular particles, the maximum particle length is determined as shown in FIG. This “maximum particle length” can be measured using a metallographic microscope. In the second embodiment, the “average maximum particle length” is an average value of the maximum particle length of 300 randomly selected floor covering material particles.

  The floor covering material particles are not particularly limited, but it is preferable to use particles composed of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. By using such a floor covering material, the reaction between the mixture and the hearth and the reaction between the mixture and the floor covering material can be further suppressed, and high-quality ferronickel can be produced, and also effectively. Can be recovered. Also, by reusing floor coverings, smelting costs can be reduced.

The specific surface area of the bedding material particles is preferably 0.002 .mu.m ^-1 or more, and more preferably 0.003 .mu.m ^-1 or more. On the other hand, the specific surface area is preferably 2.5 [mu] m ^-1 or less, more preferably 2.0 .mu.m ^-1 or less. By using the floor covering material having the specific surface area of the floor covering material in such a range, the contact area between the mixture placed on the floor covering material and the floor covering material becomes more appropriate.

  The average maximum particle length of the floor covering material particles is preferably 17.0 μm or more, more preferably 20.0 μm or more. On the other hand, the average maximum particle length of the floor covering material particles is preferably 1500 μm or less, more preferably 1200 μm or less, and even more preferably 1000 μm or less. By using the floor covering material having the average maximum particle length of the floor covering material in such a range, the contact area between the mixture placed on the floor covering material and the floor covering material becomes more appropriate.

  Although the arrangement ratio of the mixture to the hearth is not particularly limited, for example, it is preferable to arrange the mixture so as to be 1% or more of the area of the hearth when the hearth is viewed in plan, and 1.5% It is more preferable to arrange the mixture so as to be as described above, and it is further preferable to arrange the mixture so as to be 2% or more. On the other hand, the arrangement ratio of the mixture with respect to the hearth is preferably such that the mixture is 50% or less of the area of the hearth, more preferably 45% or less. %, And more preferably, the mixture is 40% or less.

(3-3) Reduction Step of Third Aspect In the third aspect, the floor covering material is composed of particles (floor covering particles), and the maximum particle length contained in the floor covering material is 50.0 μm or less. A reduction furnace in which the number of bedding material particles is 1% or more and 40% or less with respect to the total number of bedding material particles contained in the bedding material, and whose average maximum particle length is 40.0 μm or more and 1050 μm or less. And a mixture of nickel oxide ore and a carbonaceous reducing agent is placed on the bed material to reduce nickel oxide ore.

Here, in the third aspect, “maximum particle length” refers to the longest side or diameter of a specific particle. Specifically, for example, when the particles are elliptical, the maximum particle length is a long diameter, and when the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. FIG. 5 is a schematic diagram showing the maximum particle length of the irregular-shaped particles. In the case of irregular particles, the maximum particle length is determined as shown in FIG. This “maximum particle length” can be measured using a metallographic microscope. In the third embodiment, the “average maximum particle length” refers to an average value of the maximum particle length of 300 randomly selected floor covering material particles, and is obtained by the following equation (3).
Average maximum particle length = sum of maximum particle length of 300 floor covering material particles / 300 (3)

  In this way, the specific floor covering material is placed on the hearth of the reduction furnace, and the mixture is placed on the floor covering material and subjected to the reduction treatment, whereby the mixture placed on the floor covering material and the furnace are processed. A reaction with the floor and a reaction between the mixture and the floor covering material can be suppressed, and high-quality ferronickel can be manufactured and can be effectively recovered. Also, by reusing floor coverings, smelting costs can be reduced.

  As described above, as the floor covering material, the number of floor covering material particles having a maximum particle length of 50.0 μm or less contained in the floor covering material is 1 to the total number of floor covering material particles contained in the floor covering material. % Or more and 40% or less. The number of floor covering material particles having a maximum particle length of 50.0 μm or less contained in the floor covering material is not particularly limited as long as it is within the above-described range. It is preferably at least 1.2%, more preferably at least 1.5%, even more preferably at least 1.7%, particularly preferably at least 2%, based on the number of material particles. preferable. On the other hand, the number of floor covering material particles having a maximum particle length of 50.0 μm or less contained in the floor covering material is, for example, 37% or less of the total number of floor covering material particles contained in the floor covering material. Is preferably 35% or less, more preferably 32% or less, and particularly preferably 30% or less.

  Further, as described above, as the floor covering material, one having an average maximum particle length of 40.0 μm or more and 1050 μm or less is used. Further, the average maximum particle length is preferably at least 42.0 μm, more preferably at least 45.0 μm, further preferably at least 47.0 μm, particularly preferably at least 50.0 μm. . On the other hand, the average maximum particle length is preferably 1030 μm or less, more preferably 1000 μm or less.

The specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, more preferably 0.002 .mu.m ^-1 or more, is 0.003 .mu.m ^-1 or Is more preferable. On the other hand, the specific surface area is, for example, preferably 3.0 μm ⁻¹ or less, more preferably 2.5 μm ⁻¹ or less, and still more preferably 2.0 μm ⁻¹ or less. By using a floor covering material having a specific surface area in such a range, the contact area between the mixture and the floor covering material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring device.

  Although there is no particular limitation on the floor covering material, it is preferable to use a material composed of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. By using such a floor covering material, the reaction between the mixture and the hearth and the reaction between the mixture and the floor covering material can be further suppressed, and high-quality ferronickel can be manufactured. In addition, the floor covering material can be reused, and as a result, the cost of smelting can be reduced.

  Although the arrangement ratio of the mixture to the hearth is not particularly limited, for example, it is preferable to arrange the mixture so as to be 1% or more of the area of the hearth when the hearth is viewed in plan, and 1.5% It is more preferable to arrange the mixture so as to be as described above, and it is further preferable to arrange the mixture so as to be 2% or more. On the other hand, the arrangement ratio of the mixture with respect to the hearth is preferably such that the mixture is 50% or less of the area of the hearth, more preferably 45% or less. %, And more preferably, the mixture is 40% or less.

(3-4) Reduction Step of Fourth Aspect In the fourth aspect, a floor covering material is laid on the hearth of a reduction furnace, and the area of the hearth when the hearth is viewed in a plan view is placed on the floor covering material. The nickel oxide ore is reduced by disposing the mixture so as to be 50% or less.

  In this way, by reducing the mixture by arranging the mixture at a specific arrangement ratio (arrangement area ratio) on the floor covering material, the reaction between the mixture and the hearth and the reaction between the mixture and the floor covering material are suppressed. , And high-quality ferronickel can be produced and can be effectively recovered. Also, by reusing floor coverings, smelting costs can be reduced.

  As described above, the mixture is disposed on the hearth of the reduction furnace such that the area of the hearth is 50% or less of the area of the hearth when the hearth is viewed in plan. By arranging the mixture on the hearth of the reduction furnace so as to be 50% of the area of the hearth in plan view, the contact area between the mixture and the floor covering material becomes appropriate. If the contact area between the mixture and the floor covering material is too large, the reaction between the two may proceed. On the other hand, if the contact area is too small, the generated slag or metal may permeate into the gap between the floor coverings.

  Further, as for the arrangement ratio (arrangement area ratio) of the mixture with respect to the hearth, for example, the mixture is preferably arranged so as to be 3% or more of the area of the hearth, and the mixture is arranged so as to be 5% or more. Is more preferable. On the other hand, it is preferable to arrange the mixture on the hearth of the reduction furnace so that the mixture becomes 45% or less, more preferably the mixture is arranged so as to be 42% or less, and the mixture is arranged so as to be 40% or less. Is more preferably arranged. By arranging the mixture in such an area with respect to the hearth, the contact area between the mixture and the floor covering material becomes more appropriate.

  Here, as described above, a floor covering material is laid on the hearth. With this floor covering material, the mixture and the hearth are subjected to a reduction treatment without contacting each other. Drawing 6 is a mimetic diagram showing an example of installation of a spherical mixture to floor covering material. FIG. 7 is a schematic diagram illustrating an example of installation of a rectangular parallelepiped mixture on a floor covering material. As shown in FIGS. 6 and 7, the mixture is preferably installed so that at least a part thereof is embedded in the floor covering material. By installing the mixture in this manner, the mixture can be stably installed on the floor covering material, and even if the reduction reaction proceeds while the hearth moves, the mixture may roll or move and the reactivity may vary. Can be suppressed. Further, the contact area between the mixture and the floor covering material can be kept constant within a certain range, and the reactivity is less likely to vary.

  Although there is no particular limitation on the shape of the floor covering material, it is preferable to use one composed of particles (floor covering particles). By using a material composed of particles as the floor covering material, the contact area between the mixture and the floor covering material becomes more appropriate, and also, the operability when laying on the hearth and the recovery when recovering from the hearth Excellent handleability.

As bedding material, if used those composed of particles, the specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, 0.002 .mu.m ^-1 or Is more preferable, and more preferably 0.003 μm ⁻¹ or more. On the other hand, the specific surface area is, for example, preferably 3.0 μm ⁻¹ or less, more preferably 2.5 μm ⁻¹ or less, and still more preferably 2.0 μm ⁻¹ or less. By using a floor covering material having a specific surface area in such a range, the contact area between the mixture and the floor covering material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring device.

  In addition, when using a material composed of particles as the floor covering material, the size of the floor covering material particles is not particularly limited, for example, the average maximum particle length is preferably 20.0μm or more and 1000μm or less, More preferably, it is 50.0 μm or more and 700 μm or less. When the average maximum particle length of the floor covering material is in such a range, the contact area between the mixture and the floor covering material becomes more appropriate.

  Here, in the fourth aspect, the “maximum particle length” refers to the longest side or diameter of a specific particle. Specifically, for example, when the particles are elliptical, the maximum particle length is a long diameter, and when the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. This “maximum particle length” can be measured using a metallographic microscope. In the fourth embodiment, the “average maximum particle length” is an average value of the maximum particle length of 100 floor covering material particles selected at random.

  The floor covering material is not particularly limited, but it is preferable to use a material composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. By using such a floor covering material, the reaction between the mixture and the hearth and the reaction between the mixture and the floor covering material can be further suppressed, and high-quality ferronickel can be manufactured. In addition, the floor covering material can be reused, and as a result, the cost of smelting can be reduced.

(3-5) Other Conditions Hereinafter, common reduction conditions and common reduction furnaces used in the reduction processes of the first to fourth aspects will be described.

  In the reduction treatment using a reduction furnace, nickel oxide, which is a metal oxide contained in nickel oxide ore, is reduced as completely as possible and preferentially to iron. It is preferable to perform so-called partial reduction, in which iron oxide derived from iron ore or the like mixed only partially is reduced to obtain ferronickel of the desired nickel grade.

  Specifically, the reduction temperature is not particularly limited, but is preferably in the range of 1200 ° C. to 1450 ° C., and more preferably in the range of 1300 ° C. to 1400 ° C. By performing the reduction in such a temperature range, a reduction reaction can be uniformly generated, and a metal (ferronickel metal) in which variation in quality is suppressed can be generated. More preferably, by performing the reduction at a reduction temperature in the range of 1300 ° C. or more and 1400 ° C. or less, a desired reduction reaction can be caused in a relatively short time.

  Usually, when reducing at a high temperature of 1300 ° C. or more using a reduction furnace having a metal hearth, slag or metal generated from the mixture reacts with the hearth and may damage the hearth in a short time. . Further, a metal component or the like of the hearth may be mixed into the mixture or the reduced metal, and the quality of the obtained metal may be deteriorated. Further, when a normal floor covering material such as coal or coke is used, slag or metal generated from the mixture may react with such floor covering material. Although such a reaction can be tolerated to a small extent, the floor covering may be deteriorated and cannot be reused.

  At the time of the reduction treatment, the internal temperature of the reduction chamber in the reduction furnace is increased until the reduction temperature falls within the above-described range, and the temperature is maintained after the temperature increase.

[Rotary hearth furnace]
As described above, for example, a movable hearth furnace or a rotary hearth furnace can be used as the reduction furnace. According to such a reduction furnace, the metal contained in the metal oxide can be effectively metallized, and the smelting process can be performed efficiently. Hereinafter, as an example of the reduction furnace, a configuration of a rotary hearth furnace will be described with reference to FIG.

  FIG. 3 is a diagram (plan view) illustrating a configuration example of a rotary hearth furnace in which a hearth rotates. As shown in FIG. 3, the rotary hearth furnace 1 has a region 10 in which the hearth rotates, and the region 10 is divided into four parts to form processing chambers (10 a, 10 b, 10 c, 10 d). I have. Specifically, in the rotary hearth furnace 1, for example, all four processing chambers denoted by reference numerals "10a" to "10d" can be reduction chambers for performing reduction processing. When a temperature holding step S34 to be described later is performed after the processing in the reduction step S33, for example, the processing chambers "10a", "10b", and "10c" are set as reduction chambers, and the processing chamber "10d" is set as temperature holding. A temperature holding chamber for performing the process in step S34 can be provided. Further, when a cooling step S5 described later is performed after the processing in the reduction step S33, for example, the processing chambers “10a”, “10b”, and “10c” are set as reduction chambers, and the processing chamber “10d” is set as the cooling step S5. Can be a temperature holding chamber for performing the processing in.

  In order to strictly control the reaction temperature and suppress the energy loss, it is preferable that the partition between the steps, that is, between the processing chambers is partitioned by a partition wall. As described above, according to the rotary hearth furnace having a structure capable of partitioning a sub-size of each step, as described later, the processing in the reduction step S33 and the processing in the temperature holding step S34 can suppress energy loss. However, it can be performed using the same rotary hearth furnace. However, if the partition wall is of a fixed type, it may be difficult to transport between processes, and particularly to charge and discharge the material into the rotary hearth furnace. It is preferable to have a structure that can be opened and closed to the extent that it does not interfere with the operation.

  The number of processing chambers formed by dividing the area 10 where the hearth rotates is not limited to four as illustrated in FIG. Further, the number of reduction chambers and the number of temperature holding chambers are not limited to the above-described example, and can be appropriately set according to the processing time and the like.

  As described above, the rotary hearth furnace 1 includes a hearth that rotates and moves on a plane, and the hearth on which the mixture is placed is rotated at a predetermined speed, so that each of the processing chambers (10a, 10a, 10b, 10c, 10d), and processing is performed at the time of passing. The arrows on the rotary hearth furnace 1 in FIG. 3 indicate the direction of rotation of the hearth and the direction of movement of the processed material (mixture).

  Further, in the rotary hearth furnace 1, a drying chamber 20 provided outside the furnace and a preheating chamber 30 are connected, and as described above, after the mixture is subjected to the drying process in the drying chamber 20, The mixture after drying is moved to the preheating chamber 30 and preheat-treated, and the mixture after preheating is sequentially transferred into the rotary hearth furnace 1. Further, the rotary hearth furnace 1 is connected to a cooling chamber 40 provided outside the furnace, and the reduced product obtained through the reduction chamber or the temperature holding chamber (10d) is subjected to a cooling process in the cooling chamber 40. (A cooling step S35 described later).

(4) Temperature holding step A temperature holding step S34 of holding the reduced product obtained through the reduction step S33 in the rotary hearth furnace at a predetermined high temperature condition may be performed. In this way, the reduced product obtained by the reduction treatment at the predetermined reduction temperature in the reduction step S33 is not immediately cooled, but is maintained in a high-temperature atmosphere, so that the metal component generated in the reduced product is reduced. It can settle and coarsen.

  In the temperature holding step S34, even if nickel metal or slag is generated by the reduction reaction by using the floor covering material, the nickel metal or slag does not react with the hearth, and the slag does not permeate or stick to the hearth.

  When the metal component in the reduced product is small in the state obtained by the reduction treatment, for example, when the metal is a bulk metal having a size of about 200 μm or less, the metal and the slag are separated in the subsequent separation step S4. Becomes difficult. For this reason, if necessary, by maintaining the reduced product at a high temperature, the metal having a specific gravity greater than that of the slag in the reduced product is settled and agglomerated, and the metal is coarsened.

  When the metal is coarsened to a level at which there is no problem in production by the reduction treatment in the reduction step S33, it is not particularly necessary to provide the temperature holding step S34.

  Specifically, it is preferable that the holding temperature of the reduced product in the temperature holding step S34 be in a high temperature range of 1300 ° C to 1500 ° C. By keeping the reduced product at a high temperature in such a range, the metal component in the reduced product can be efficiently settled to form a coarse metal. If the holding temperature is lower than 1300 ° C., a large part of the reduced product becomes a solid phase, so that the metal component does not settle or it takes time even if it is settled. On the other hand, when the holding temperature exceeds 1500 ° C., the reaction between the obtained reduced product and the floor covering material progresses, and it may not be possible to collect the reduced product, or the furnace may be damaged. .

  Here, the processing in the temperature holding step S34 is performed continuously after the reduction processing in the rotary hearth furnace 1 used in the reduction step S33. That is, as described with reference to FIG. 3, in the rotary hearth furnace 1, for example, the processing chambers “10a”, “10b”, and “10c” are set as reduction chambers, and the processing chamber “10d” is set in the temperature holding step S34. The reduced product obtained by passing through the reduction chambers (10a, 10b, 10c) is maintained in a predetermined temperature range in the temperature holding chamber (10d).

  As described above, the process of maintaining the reduced product obtained through the reduction process at a predetermined temperature is continuously performed using the rotary hearth furnace 1, so that the metal component in the reduced product is efficiently settled. Can be coarsened. Moreover, by performing the processing in the reduction step S33 and the processing in the temperature holding step S34 continuously using the rotary hearth furnace 1 instead of using separate furnaces, the heat loss between each processing can be reduced and the efficiency can be reduced. Enable operations.

(5) Cooling Step In the cooling step S35, the reductant obtained through the reductive step S33 or the reductant that has been maintained at a high temperature for a predetermined time in the temperature maintaining step S34 is separated and recovered in the subsequent separating step S4. Cool to a temperature where it can.

  Since the cooling step S35 is a step of cooling the reduced product obtained as described above, it is preferable to perform the cooling step S35 in a cooling chamber connected to the outside of the rotary hearth furnace 1. FIG. 3 shows a configuration example of the cooling chamber 40 connected to the rotary hearth furnace 1. The cooling chamber 40 is provided outside the rotary hearth furnace 1. As described above, by performing the cooling treatment in the cooling chamber 40 provided outside the furnace of the rotary hearth furnace 1, a decrease in the internal temperature of the rotary hearth furnace 1 can be prevented, and energy loss can be suppressed. it can. This enables efficient production of ferronickel.

  The temperature in the cooling step S35 (hereinafter, also referred to as “recovery temperature”) is a temperature at which the reduced product can be substantially treated as a solid, and is preferably as high as possible. By increasing the temperature at the time of recovery as much as possible, even when the hearth of the rotary hearth furnace 1 that rotates and returns to the connection point with the preheating chamber 30 that executes the preheating step S32, energy loss can be reduced, and reheating can be performed. The required energy can be further saved.

  Specifically, the temperature at the time of recovery is preferably set to 600 ° C. or higher. By setting the temperature at the time of recovery to a high temperature in this way, the energy required for reheating can be significantly reduced, and a low-cost and efficient smelting process can be performed. Further, by reducing the temperature difference inside the rotary hearth furnace 1, the thermal stress applied to the hearth, the furnace wall and the like can be reduced, and the life of the rotary hearth furnace 1 can be greatly extended. Furthermore, malfunctions during operation can be greatly reduced.

<2-4. Separation process>
In the separation step S4, metal (ferronickel metal) is separated and collected from the reduced product generated in the reduction processing step S3. Specifically, in the separation step S4, a mixture (reduced material) in which a metal phase (metal solid phase) and a slag phase (slag solid phase) are mixed, which is obtained by subjecting the mixture to reduction heat treatment, is converted to a metal phase. Is separated and collected.

  As a method of separating the metal phase and the slag phase from the mixture of the metal phase and the slag phase obtained as a solid, for example, in addition to removing unnecessary substances by sieving, separation by specific gravity, separation by magnetic force, and the like Method can be used. In addition, the obtained metal phase and slag phase can be easily separated because of poor wettability, and for large inclusions, for example, a predetermined head is provided for dropping, or when sieving. By giving an impact such as giving a predetermined vibration, the metal phase and the slag phase can be easily separated from the mixture.

  By separating the metal phase and the slag phase in this way, the metal phase can be recovered and made into a ferronickel product.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
(Mixing process)
A nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, a binder, and coal as a carbonaceous reducing agent are mixed using a mixer while adding an appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total chemical equivalent required to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or shortage is 100%. Was contained in an amount corresponding to.

  Then, the mixture obtained by mixing with the mixer was kneaded with a twin-screw kneader.

(Pretreatment process for reduction input)
Next, the mixture sample obtained by kneading was formed into spherical pellets of φ18 ± 1.5 mm using a pan-type granulator.

(Reduction process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, the reduction treatment was performed using the mixture sample while changing the treatment conditions. As shown in FIG. 3, as the rotary hearth furnace 1, a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously with the drying chamber 20, and a processing chamber in the furnace, outside the area 10. The one connected to the cooling chamber 40 for cooling the reduced product obtained through 10a to 10d was used. In Example 1, the processing chamber 10d was used as a cooling chamber.

  Specifically, the pellet sample was charged into a drying chamber 20 connected to the outside of the rotary hearth furnace 1 and subjected to a drying treatment. In the drying treatment, hot air at 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere substantially containing no oxygen so that the solid content in the pellets is about 70% by weight and the water content is about 30% by weight. Made by. Table 3 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

  Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 provided continuously to the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C or more and 1280 ° C or less, and the preheating of the pellets is performed. Heat treatment was performed.

  Subsequently, the pellets after the preheat treatment were transferred to the inside of the rotary hearth furnace 1 to perform a reduction treatment and a temperature holding treatment. Specifically, the rotary hearth furnace 1 has four processing chambers by dividing the area 10 in which the hearth rotates and moves, and all of the four processing chambers 10a to 10d perform reduction processing. Room.

  The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1, quickly cooled to room temperature while flowing nitrogen, and taken out to the atmosphere. The reduced product was recovered from the rotary hearth furnace 1 by transferring the reduced product to the cooling chamber 40, and the reduced product was recovered along a guide provided in the cooling chamber 40.

  In Examples 1-1 to 1-48, a floor covering material composed of particles was laid on a hearth, and a pellet of the mixture was placed thereon to perform a reduction treatment. In Comparative Examples 1-1 to 1-3, the pellets were directly placed on a metal hearth to perform a reduction treatment. Tables 4 to 6 below show the conditions of the reduction treatment in the reduction steps of Examples 1 to 48 and Comparative Examples 1-1 to 1-3.

  The average maximum particle length was determined from the average value of the maximum particle length of 300 floor covering material particles randomly selected and measured using a metallographic microscope. The volume of the floor covering material is determined by measuring the total weight of 300 particles used to determine the average value of the maximum particle length, and dividing the total weight by the density of the material constituting the floor covering material. I asked.

  The pellets, floor covering material and hearth after the reduction treatment were visually confirmed to confirm the mutual reaction. The results are shown in Tables 4 to 6 below.

The nickel quality of the sample taken out was analyzed by an ICP emission spectrometer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following equation (4), and the nickel content in the metal was calculated by the following equation (5). Tables 4 to 6 below show the nickel metal ratio and the nickel content in the metal of the samples obtained in Examples 1-1 to 1-48 and Comparative Examples 1-1 to 1-3.
Nickel metallization rate = amount of metallized Ni in pellets charged with reduction treatment / (amount of all Ni in pellets charged with reduction treatment) × 100 (%) (4)
Nickel content in metal = Amount of metallized Ni in pellets charged for reduction treatment / (Total amount of Ni and Fe metalized in pellets charged for reduction treatment) × 100 (%) (5)

  As described above, in Examples 1-1 to 1-48, by using the predetermined floor covering material, the floor covering material and the hearth do not react with the sample, and as a result, high quality with less impurities and the like is obtained. Was manufactured. Further, since the floor covering material can be reused, it can be realized at low cost. Further, since the metal component is large, the metal is likely to be coarse.

  On the other hand, in Comparative Examples 1-1 to 1-3, the sample reacted with the hearth and was mixed, and the metal could not be recovered effectively.

[Example 2]
(Mixing process)
A nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, a binder, and coal as a carbonaceous reducing agent are mixed using a mixer while adding an appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent has a carbon content of 36% when the total chemical equivalent required to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or shortage is 100%. Was contained in an amount corresponding to.

  Then, the mixture obtained by mixing with the mixer was kneaded with a twin-screw kneader.

(Pretreatment process for reduction input)
Next, the mixture sample obtained by kneading was formed into spherical pellets of φ16 ± 1.5 mm using a pan-type granulator.

(Reduction process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, a floor covering material composed of particles is spread on the hearth of the rotary hearth furnace 1, and the processing conditions are changed using the mixture sample. A reduction treatment was performed. As shown in FIG. 3, as the rotary hearth furnace 1, a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously with the drying chamber 20, and a processing chamber in the furnace, outside the area 10. The one connected to the cooling chamber 40 for cooling the reduced product obtained through 10a to 10d was used. In Example 2, the processing chamber 10d was used as a cooling chamber.

  Specifically, the pellet sample was charged into a drying chamber 20 connected to the outside of the rotary hearth furnace 1 and subjected to a drying treatment. In the drying treatment, hot air at 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere substantially containing no oxygen so that the solid content in the pellets is about 70% by weight and the water content is about 30% by weight. Made by. Table 7 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

  Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 provided continuously to the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C or more and 1280 ° C or less, and the preheating of the pellets is performed. Heat treatment was performed.

  Subsequently, the pellets after the preheat treatment were transferred to the inside of the rotary hearth furnace 1 to perform a reduction treatment and a temperature holding treatment. Specifically, the rotary hearth furnace 1 has four processing chambers by dividing the area 10 in which the hearth rotates and moves, and all of the four processing chambers 10a to 10d perform reduction processing. Room.

  The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1, quickly cooled to room temperature while flowing nitrogen, and taken out to the atmosphere. The reduced product was recovered from the rotary hearth furnace 1 by transferring the reduced product to the cooling chamber 40, and the reduced product was recovered along a guide provided in the cooling chamber 40.

  In Tables 8 to 10 below, in Examples 2-1 to 2-48 and Comparative Examples 2-1 to 2-12, the material of the floor covering, the specific surface area of the floor covering, the average maximum particle length of the floor covering, Shows the reduction temperature and reduction time.

  The specific surface area of the floor covering material was measured using a specific surface area measuring device (Flowsorb III2305) of Shimadzu Corporation. The average maximum particle length was determined from the average value of the maximum particle length of 300 floor covering material particles randomly selected and measured using a metallographic microscope. The volume of the floor covering material is determined by measuring the total weight of 300 particles used to determine the average value of the maximum particle length, and dividing the total weight by the density of the material constituting the floor covering material. I asked.

The nickel quality of the sample taken out was analyzed by an ICP emission spectrometer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following equation (4), and the nickel content in the metal was calculated by the following equation (5).
Nickel metallization rate = amount of metallized Ni in pellets charged with reduction treatment / (amount of all Ni in pellets charged with reduction treatment) × 100 (%) (4)
Nickel content in metal = amount of metallized Ni in pellets charged in reduction treatment / (total amount of metalized Ni and Fe in pellets charged in reduction treatment) × 100 (%) (5)

Further, each of the collected samples was pulverized by wet processing, and then metal was collected by magnetic force sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the amount of recovered Ni. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

  Tables 8 to 10 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery of the samples obtained in Examples 2-1 to 2-48 and Comparative Examples 2-1 to 2-12.

  As described above, in Examples 2-1 to 2-48, by using a predetermined floor covering material, uniform and stable reduction can be performed, and as a result, the Ni metallization rate and the recovery rate are high, High quality ferronickel for Ni could be produced. In addition, the floor covering material can be used continuously, and nickel can be produced at low cost. Furthermore, since the Ni content ratio is large, the metal is likely to be coarse.

[Example 3]
(Mixing process)
A nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, a binder, and coal as a carbonaceous reducing agent are mixed using a mixer while adding an appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total chemical equivalent required to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or shortage is 100%. Was contained in an amount corresponding to.

  Then, the mixture obtained by mixing with the mixer was kneaded with a twin-screw kneader.

(Pretreatment process for reduction input)
About Examples 3-1 to 3-12, Examples 3-25 to 3-36, Comparative examples 3-1, Comparative examples 3-2, Comparative examples 3-5, and Comparative examples 3-6, they were obtained by kneading. The obtained mixture sample was formed into a spherical pellet of φ16 ± 1.5 mm using a pan-type granulator.

  About Examples 3-13 to 3-24, Examples 3-37 to 3-48, Comparative Examples 3-3, Comparative Examples 3-4, Comparative Examples 3-7, and Comparative Examples 3-8, 15 mm length x width The mixture was fitted into a mold and molded into a rectangular parallelepiped shape having a size of 15 mm × 10 mm.

(Reduction process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, a floor covering material composed of particles is spread on the hearth of the rotary hearth furnace 1, and the processing conditions are changed using the mixture sample. A reduction treatment was performed. As shown in FIG. 3, as the rotary hearth furnace 1, a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously with the drying chamber 20, and a processing chamber in the furnace, outside the area 10. The one connected to the cooling chamber 40 for cooling the reduced product obtained through 10a to 10d was used. In Example 3, the processing chamber 10d was used as a cooling chamber.

  Specifically, the pellet sample was charged into a drying chamber 20 connected to the outside of the rotary hearth furnace 1 and subjected to a drying treatment. In the drying treatment, hot air at 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere substantially containing no oxygen so that the solid content in the pellets is about 70% by weight and the water content is about 30% by weight. Made by. Table 11 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

  Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 provided continuously to the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C or more and 1280 ° C or less, and the preheating of the pellets is performed. Heat treatment was performed.

  Subsequently, the pellets after the preheat treatment were transferred to the inside of the rotary hearth furnace 1 to perform a reduction treatment and a temperature holding treatment. Specifically, the rotary hearth furnace 1 has four processing chambers by dividing the area 10 in which the hearth rotates and moves, and all of the four processing chambers 10a to 10d perform reduction processing. Room.

  The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1, quickly cooled to room temperature while flowing nitrogen, and taken out to the atmosphere. The reduced product was recovered from the rotary hearth furnace 1 by transferring the reduced product to the cooling chamber 40, and the reduced product was recovered along a guide provided in the cooling chamber 40.

  Tables 12 to 14 below show the material of the floor covering material, the ratio of the number of particles having a maximum particle length of 50.0 μm or less, and the floor covering in Examples 3-1 to 3-48 and Comparative examples 3-1 to 3-12. The average maximum particle length, reduction temperature and reduction time of the material are shown.

  The specific surface area of the floor covering material was measured using a specific surface area measuring device (Flowsorb III2305) of Shimadzu Corporation. The average value of the maximum particle length was determined by using a metallurgical microscope, and the average value of the maximum particle length of 300 floor covering material particles randomly selected and measured.

The nickel quality of the sample taken out was analyzed by an ICP emission spectrometer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following equation (4), and the nickel content in the metal was calculated by the following equation (5).
Nickel metallization rate = amount of metallized Ni in pellets charged with reduction treatment / (amount of all Ni in pellets charged with reduction treatment) × 100 (%) (4)
Nickel content in metal = Amount of metallized Ni in pellets charged for reduction treatment / (Total amount of Ni and Fe metalized in pellets charged for reduction treatment) × 100 (%) (5)

Further, each of the collected samples was pulverized by wet processing, and then metal was collected by magnetic force sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the amount of recovered Ni. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

  Tables 12 to 14 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery of the samples obtained in Examples 3-1 to 3-48 and Comparative examples 3-1 to 3-12.

  Thus, in Examples 3-1 to 3-48, by using a predetermined floor covering material, uniform and stable reduction can be performed, and as a result, the Ni metallization rate and the recovery rate are high, High quality ferronickel for Ni could be produced. In addition, the floor covering material can be used continuously, and nickel can be produced at low cost. Furthermore, since the Ni content ratio is large, the metal is likely to be coarse.

[Example 4]
(Mixing process)
A nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, a binder, and coal as a carbonaceous reducing agent are mixed using a mixer while adding an appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total chemical equivalent required to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or shortage is 100%. Was contained in an amount corresponding to.

  Then, the mixture obtained by mixing with the mixer was kneaded with a twin-screw kneader.

(Pretreatment process for reduction input)
Examples 4-1 to 4-12, Examples 4-25 to 4-36, Comparative Examples 4-1, Comparative Examples 4-2, Comparative Examples 4-5 and 4-6 were obtained by kneading. The obtained mixture sample was formed into a spherical pellet of φ15 ± 1.5 mm using a pan-type granulator.

  About Examples 4-13 to 4-24, Examples 4-37 to 4-48, Comparative Examples 4-3, Comparative Examples 4-4, Comparative Examples 4-7, and Comparative Examples 4-8, 15 mm length × width The mixture sample was fitted into a mold and formed into a rectangular parallelepiped shape of 15 mm × 10 mm in height.

(Reduction process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, the reduction treatment was performed using the mixture sample while changing the treatment conditions. As shown in FIG. 3, as the rotary hearth furnace 1, a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously with the drying chamber 20, and a processing chamber in the furnace, outside the area 10. The one connected to the cooling chamber 40 for cooling the reduced product obtained through 10a to 10d was used. In Example 4, the processing chamber 10d was used as a cooling chamber.

  Specifically, the pellet sample was charged into a drying chamber 20 connected to the outside of the rotary hearth furnace 1 and subjected to a drying treatment. In the drying treatment, hot air at 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere substantially containing no oxygen so that the solid content in the pellets is about 70% by weight and the water content is about 30% by weight. Made by. Table 15 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

  Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 provided continuously to the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C or more and 1280 ° C or less, and the preheating of the pellets is performed. Heat treatment was performed.

  Subsequently, the pellets after the preheat treatment were transferred to the inside of the rotary hearth furnace 1 to perform a reduction treatment and a temperature holding treatment. Specifically, the rotary hearth furnace 1 has four processing chambers by dividing the area 10 in which the hearth rotates and moves, and all of the four processing chambers 10a to 10d perform reduction processing. Room.

  The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1, quickly cooled to room temperature while flowing nitrogen, and taken out to the atmosphere. The reduced product was recovered from the rotary hearth furnace 1 by transferring the reduced product to the cooling chamber 40, and the reduced product was recovered along a guide provided in the cooling chamber 40.

  In Tables 16 to 18 below, in Examples 4-1 to 4-48 and Comparative examples 4-1 to 4-12, the material of the floor covering material, the shape of the floor covering material, the area ratio of the mixture to the hearth, and the reduction Shows temperature and reduction time.

The nickel quality of the sample taken out was analyzed by an ICP emission spectrometer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following equation (4), and the nickel content in the metal was calculated by the following equation (5).
Nickel metallization rate = amount of metallized Ni in pellets charged with reduction treatment / (amount of all Ni in pellets charged with reduction treatment) × 100 (%) (4)
Nickel content in metal = amount of metallized Ni in pellets charged in reduction treatment / (total amount of metalized Ni and Fe in pellets charged in reduction treatment) × 100 (%) (5)

Further, each of the collected samples was pulverized by wet processing, and then metal was collected by magnetic force sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the amount of recovered Ni. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

  Tables 16 to 18 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery of the samples obtained in Examples 4-1 to 4-48 and Comparative Examples 4-1 to 4-8.

  As described above, in Examples 4-1 to 4-48, a uniform and stable reduction can be performed by disposing the mixture at a specific ratio with respect to the hearth. The rate was high, and high quality ferronickel for Ni could be produced. In addition, the floor covering material can be used continuously, and nickel can be produced at low cost. Furthermore, since the Ni content ratio is large, the metal is likely to be coarse.

1 Rotary hearth furnace 10 Area 10a, 10b, 10c, 10d Processing chamber (reduction chamber, temperature holding chamber, cooling chamber)
Reference Signs List 20 drying room 30 preheating room 40 cooling room 51 mixture (spherical)
52 Floor covering material 61 Mixture (cubic)
62 Floor covering material

Claims (11)

In a reduction furnace, a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent,
A metal oxide smelting method for heating and reducing the mixture on a floor covering made of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. The floor covering material is composed of particles of the material (floor covering particles),
The metal oxide smelting method according to claim 1, wherein the average floor covering material volume ratio obtained from the following formulas (1) and (2) is 3% or more and 85% or less.
Average floor covering volume ratio = sum of floor covering material volume ratios of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere whose diameter is the maximum particle length of floor covering particles) × 100 (2) The floor covering material is composed of particles of the material (floor covering particles),
The metal oxide smelting method according to claim 1 or 2, wherein the average maximum particle length determined by the following formula (3) is 10 µm or more and 6000 µm or less.
Average maximum particle length = sum of maximum particle length of 300 floor covering material particles / 300 (3) In a reduction furnace, a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent,
The specific surface area is at 0.001 [mu] m ^-1 or more 3.0 [mu] m ^-1 or less, and an average maximum particle length is bedding material onto comprised particles less 2000μm or more 15.0 .mu.m (bedding material particles), the A method for smelting metal oxides in which the mixture is heated and reduced. The metal oxide smelting method according to claim 4, wherein the floor covering material particles are composed of at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite. In a reduction furnace, a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent,
Laying a floor covering material on the hearth of the reduction furnace,
The floor bedding material is composed of particles (floor bedding material particles), and the total number of floor bedding materials having a maximum particle length of 50.0 μm or less contained in the bedding material is included in the floor bedding material. 1% or more and 40% or less based on the number of particles,
The metal oxide smelting method, wherein the floor covering material particles have an average maximum particle length of 40.0 μm or more and 1050 μm or less determined by the following formula (3).
Average maximum particle length = sum of maximum particle length of 300 floor covering material particles / 300 (3) In a reduction furnace, a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent,
Laying a floor covering material on the hearth of the reduction furnace,
A metal oxide smelting method in which the mixture is arranged and heated and reduced on the floor covering so that the area of the hearth is 50% or less of the area of the hearth when the hearth is viewed in plan. The metal oxide smelting method according to claim 7, wherein the mixture has any one of a spherical shape, a cubic shape, and a rectangular parallelepiped shape. The metal oxide smelting method according to any one of claims 1 to 8, wherein the reduction temperature is 1200C or more and 1450C or less. The metal oxide smelting method according to any one of claims 1 to 9, wherein the metal oxide is a nickel oxide ore. The metal oxide smelting method according to any one of claims 1 to 10, wherein the reduced product contains ferronickel.

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