JP6428528B2 - Nickel oxide ore smelting method - Google Patents

Description

  The present invention relates to a method for smelting nickel oxide ore, and more specifically, a nickel oxide ore that is smelted by forming pellets from nickel oxide ore as a raw ore and reducing and heating the pellets in a smelting furnace. It relates to the smelting method.

  As a smelting method of nickel oxide ore called limonite or saprolite, a dry smelting method using a smelting furnace to produce nickel matte, an iron-nickel alloy (ferronickel) using a rotary kiln or moving hearth furnace A dry smelting method for manufacturing, a wet smelting method for manufacturing mixed sulfide using an autoclave, and the like are known.

  As dry smelting of nickel oxide ore, a process is generally performed in which ferro-nickel metal is obtained and slag is separated by roasting in a rotary kiln and then melting the sinter in an electric furnace. At this time, the nickel concentration in the ferronickel metal is kept high by leaving a part of iron in the slag. However, since it is necessary to melt the entire amount of nickel oxide ore to produce slag and ferronickel, it has a drawback of requiring a large amount of electric energy.

  Here, in Patent Document 1, nickel oxide ore and a reducing agent (anthracite) are charged into a rotary kiln and reduced in a semi-molten state to reduce a part of nickel and iron to metal, followed by specific gravity separation and A method for recovering ferronickel by magnetic separation has been proposed. According to this method, since ferronickel metal can be obtained without melting using electricity, there is an advantage that energy consumption is small. However, since it is a reduction in a semi-molten state, the produced metal is dispersed in small particles, and the loss of nickel metal is relatively low due to the loss in specific gravity separation and magnetic separation. is there.

  Patent Document 2 discloses a method for producing ferronickel using a moving hearth furnace. In this document, a raw material containing nickel oxide and iron oxide and a carbonaceous reducing agent are mixed to form pellets, and the mixture is heated and reduced in a moving hearth furnace to obtain a reduced mixture. It has been shown that ferronickel is obtained by melting the reduced mixture in a separate furnace. Alternatively, it has been shown to melt both or one of the slag and metal in a moving hearth furnace. However, melting the reducing mixture in a separate furnace requires a great deal of energy, similar to the melting process in an electric furnace. In addition, when melted in the furnace, the melted slag and metal are fused to the hearth, which makes it difficult to discharge out of the furnace.

  In order to prevent such a problem, that is, to prevent slag and metal from adhering to the hearth (hereinafter also referred to as “fusion”) even when melted, for example, coal is laid on the hearth, A method of placing pellets thereon is employed. According to this method, adhesion during melting can be prevented.

  Now, when selling ferronickel, it is preferable that the nickel quality in the ferronickel is high. However, when the total amount of nickel and iron contained in the nickel oxide ore is reduced, for example, in the case of limonite which is one of the nickel oxide ores, the nickel quality in the ferronickel obtained is lowered to less than 3%. In order to obtain ferronickel with high nickel quality, it is necessary to leave a part of iron as an oxide and not to be metallized, but lay coal on the hearth as a carbonaceous reducing agent. When reduced, a large amount of carbonaceous reducing agent comes into contact with the pellet, making it very difficult to suppress the reduction of iron to metal, and the quality of nickel in ferronickel is reduced. There is a problem of variation.

Japanese Patent Publication No. 01-21855 JP 2004-156140 A

  The present invention has been proposed in view of such circumstances, and is a nickel oxide ore obtained by forming pellets from nickel oxide ore and reducing and heating the pellets in a smelting furnace to obtain an iron-nickel alloy. In a smelting method, it aims at providing the smelting method which can advance the smelting reaction in a smelting process (reduction process) effectively, and can obtain the iron-nickel alloy which has high nickel quality. .

  The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, a carbonaceous reducing agent is mixed with nickel oxide ore as a raw material to produce pellets, and the pellets are placed on the hearth in a smelting furnace having a metal hearth at a predetermined temperature. The inventors have found that an iron-nickel alloy having a high nickel quality can be obtained by carrying out the reduction heat treatment so that the reduction reaction can proceed effectively, thereby completing the present invention. That is, the present invention provides the following.

  (1) A first invention of the present invention is a nickel oxide ore smelting method for forming an iron-nickel alloy by forming pellets from nickel oxide ore and reducing and heating the pellets, wherein the nickel oxide A pellet production process for producing pellets from ore, and a reduction process for reducing and heating the obtained pellets in a smelting furnace, and in the pellet production process, at least the nickel oxide ore, a carbonaceous reducing agent, The raw material containing is mixed to form a mixture, and the mixture is agglomerated to form pellets. In the reduction step, the pellets obtained in the pellet manufacturing step are converted into the smelting furnace having a metal hearth. A nickel oxide ore smelting method comprising reducing heat treatment at a temperature of 1000 ° C. or higher and 1300 ° C. or lower while being placed on a hearth.

  (2) The second invention of the present invention is the nickel oxide ore smelting method according to the first invention, wherein the metal of the metal hearth is nickel.

  (3) According to a third aspect of the present invention, there is provided the nickel oxide ore according to the first or second aspect, wherein the temperature when the pellets are charged into the smelting furnace is 600 ° C. or less. It is a smelting method.

  (4) According to a fourth aspect of the present invention, in any one of the first to third aspects, in the pellet manufacturing process, the nickel oxide contained in the formed pellet is required to be reduced to nickel metal. When the total value of the chemical equivalent and the chemical equivalent required to reduce ferric oxide contained in the pellet to metallic iron is 100%, the ratio of the carbon amount of 5% or more and 60% or less In this method, the mixing amount of the carbonaceous reducing agent is adjusted so that the nickel oxide ore is smelted.

  According to the present invention, the reduction reaction can be effectively advanced, and an iron-nickel alloy having high nickel quality can be obtained effectively.

It is process drawing which shows an example of the flow of the refining method of nickel oxide ore. It is a processing flowchart which shows an example of the flow of the process in the pellet manufacturing process in the smelting method of nickel oxide ore. It is an Ellingham figure of metal. It is a figure which shows typically the mode of the reductive reaction in a pellet when reducing heat processing are performed in a reduction process.

  Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention. In this specification, the notation “X to Y” (X and Y are arbitrary numerical values) means “X or more and Y or less”.

≪Smelting method of nickel oxide ore≫
The nickel oxide ore smelting method according to the present embodiment uses nickel oxide ore pellets that are raw ores, and the pellets are charged into a smelting furnace (reduction furnace) and subjected to reduction heating to obtain nickel quality. Is, for example, an iron-nickel alloy (ferronickel) of 4% or more.

  In the following, nickel oxide ore, which is a raw ore, is pelletized, nickel and iron in the pellet are reduced, iron-nickel alloy metal is generated, and ferronickel is produced by separating the metal. The smelting method will be described as an example.

  Specifically, in the method for smelting nickel oxide ore according to the present embodiment, as shown in FIG. 1, a pellet manufacturing step S1 for manufacturing pellets from nickel oxide ore and the obtained pellets in a reduction furnace It has reduction process S2 which carries out reduction heating at predetermined reduction temperature, and separation process S3 which isolate | separates the metal produced | generated in reduction process S2 and collect | recovers metal. In addition, you may have further the fusion | melting process which fuses the metal which isolate | separated and collect | recovered and makes ferronickel into a molten material.

<1. Pellet manufacturing process>
In the pellet manufacturing step S1, pellets are manufactured from nickel oxide ore which is a raw material ore. FIG. 2 is a process flow diagram showing an example of a process flow in the pellet manufacturing process S1. As shown in FIG. 2, the pellet manufacturing process S1 includes a mixing process S11 for mixing raw materials containing nickel oxide ore, an agglomeration process S12 for forming (granulating) the obtained mixture into a lump, A drying treatment step S13 for drying the obtained lump.

(1) Mixing treatment step The mixing treatment step S11 is a step of obtaining a mixture by mixing raw material powders containing nickel oxide ore. In this mixing treatment step S11, in addition to nickel oxide ore which is a raw material ore, a raw material powder such as a binder having a particle size of about 0.2 mm to 0.8 mm is mixed to obtain a mixture.

  Although it does not specifically limit as a nickel oxide ore which is a raw material ore, Limonite ore, saprolite ore, etc. can be used. Examples of the binder include bentonite, polysaccharides, resins, water glass, and dehydrated cake.

  Here, in this embodiment, when manufacturing pellets, a predetermined amount of carbonaceous reducing agent is mixed to form a mixture, and the mixture is formed into pellets. Although it does not specifically limit as a carbonaceous reducing agent, For example, coal powder, coke powder, etc. are mentioned. In addition, it is preferable that this carbonaceous reducing agent is equivalent to the particle size of the raw material nickel oxide ore.

  In addition, 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 pellets to nickel metal and ferric oxide contained in the pellets. The ratio of the carbon amount of 5% or more and 60% or less when the total value of both of the chemical equivalents required for reduction to metallic iron and the total value (also referred to as “total value of chemical equivalents” for convenience) is 100%. Can be adjusted.

  In this way, the amount of the carbonaceous reducing agent mixed is adjusted to a predetermined ratio, that is, a carbon amount having a ratio of 5% to 60% with respect to 100% of the total value of the chemical equivalents described above. Although it will be described in detail later, the reduction heat treatment in the next reduction step S2 is more effective in reducing the trivalent iron oxide to the divalent iron oxide and metallizing the nickel oxide. In addition, a metal shell can be formed by further reducing divalent iron oxide to metal, while a partial reduction treatment such as leaving a part of the iron oxide contained in the shell as an oxide. Can be applied. Thereby, in one pellet, ferronickel metal (metal) having a high nickel quality of, for example, 4% or more and having a recovery rate of nickel to ferronickel of 90% or more, Ferronickel slag (slag) can be generated separately.

(2) Agglomeration treatment step The agglomeration treatment step S12 is a step of forming (granulating) the mixture of the raw material powders obtained in the mixing treatment step S11 into a lump. Specifically, water necessary for agglomeration is added to the mixture obtained in the mixing step 1, and a lump production apparatus such as a rolling granulator, a compression molding machine, or an extrusion molding machine is used. Used or formed into a pellet-like lump by human hands.

  Although it does not specifically limit as a shape of a pellet, For example, it can be made spherical. In addition, the size of the lump to be pelletized is not particularly limited. For example, the size of the pellet (spherical shape) charged into the smelting furnace or the like in the reduction step S2 through a drying process and a pre-heat treatment described later. In the case of pellets, the diameter is about 10 mm to 30 mm.

(3) Drying process process Drying process process S13 is a process of drying the lump obtained in lump processing process S12. The agglomerated material that has become a pellet-like mass by the agglomeration treatment contains a moisture content of, for example, about 50% by weight, and is in a sticky state. In order to facilitate the handling of the pellet-like lump, in the drying process step S13, for example, a drying process is performed so that the solid content of the lump is about 70% by weight and the moisture is about 30% by weight.

  More specifically, the drying process for the lump in the drying step S13 is not particularly limited. For example, hot air of 300 ° C. to 400 ° C. is blown against the lump to be dried. In addition, the temperature of the lump at the time of this drying process is less than 100 degreeC.

  Table 1 below shows an example of the composition (% by weight) in the solid content of the pellet-like lump after the drying treatment. In addition, as a composition of the lump after a drying process, it is not limited to this.

  In the pellet manufacturing step S1, as described above, the raw material powder containing the nickel oxide ore which is the raw material ore is mixed, the obtained mixture is granulated (agglomerated), and dried to dry the pellet. To manufacture. At this time, when mixing the raw material powder, a carbonaceous reducing agent is mixed according to the composition as described above, and pellets are manufactured using the mixture. The size of the pellets obtained is about 10 mm to 30 mm, and the strength is such that the shape can be maintained, for example, the pellet has such strength that the proportion of pellets that collapse even when dropped from a height of 1 m is about 1% or less. Manufactured. Such pellets can withstand impacts such as dropping when charged in the subsequent reduction step S2, can maintain the shape of the pellets, and are suitable between the pellets. Since a gap is formed, the smelting reaction in the reduction step S2 proceeds appropriately.

  In addition, in this pellet manufacturing process S1, you may make it provide the pre-heating process which pre-heats the pellet which is the lump which performed the drying process in the drying process S13 mentioned above to predetermined | prescribed temperature. In this way, by performing pre-heat treatment on the lump after drying treatment to produce pellets, even when the pellets are reduced and heated at a high temperature of about 1300 ° C. in the reduction step S2, for example, It is possible to more effectively suppress pellet cracking (breakage, collapse). For example, the proportion of the collapsing pellets of all the pellets charged in the smelting furnace can be made a small proportion, and the shape of the pellets can be more effectively maintained.

  Specifically, in the preheat treatment, the pellets after the drying treatment are preheated to a temperature of 350 ° C. to 600 ° C. Moreover, it preheat-processes to the temperature of 400 to 550 degreeC preferably. Thus, by pre-heat treatment to a temperature of 350 ° C. to 600 ° C., preferably 400 ° C. to 550 ° C., the crystal water contained in the nickel oxide ore constituting the pellet can be reduced, for example, about 1300 ° C. Even when the temperature is rapidly increased after charging in the smelting furnace, the collapse of the pellet due to the detachment of the crystal water can be suppressed. Moreover, by performing such pre-heat treatment, the thermal expansion of particles such as nickel oxide ore, carbonaceous reducing agent, binder, etc. constituting the pellet proceeds slowly in two stages. Disintegration of the pellet due to the expansion difference can be suppressed. In addition, it does not specifically limit as processing time of pre-heat processing, What is necessary is just to adjust suitably according to the magnitude | size of the lump containing a nickel oxide ore, but the normal magnitude | size from which the magnitude | size of the pellet obtained will be about 10 mm-30 mm. If it is a lump-like thing, it can be set as the processing time of about 10 minutes-60 minutes.

<2. Reduction process>
In the reduction step S2, the pellets obtained in the pellet manufacturing step S1 are reduced and heated at a predetermined reduction temperature. By the reduction heat treatment of the pellets in the reduction step S2, a smelting reaction (reduction reaction) proceeds, and metal and slag are generated.

  Specifically, the reduction heat treatment in the reduction step S2 is performed using a smelting furnace (reduction furnace) or the like, and by charging a pellet containing nickel oxide ore into a smelting furnace heated to a predetermined temperature. Reduce and heat.

  Although it does not specifically limit as temperature at the time of charging a pellet in a smelting furnace, It is preferable that it is 600 degrees C or less. Moreover, it is more preferable to set it as 550 degrees C or less from a viewpoint of suppressing more efficiently the possibility that a carbonaceous reducing agent will burn.

  If the temperature at which the pellets are charged into the smelting furnace exceeds 600 ° C., the carbonaceous reducing agent contained in the pellets may start to burn. On the other hand, in the case of the process of continuously performing the reduction heat treatment, if the temperature is lowered too much, it is disadvantageous in terms of cost of raising the temperature, so the lower limit value is not particularly limited but is preferably 500 ° C. or higher. Even if the temperature at the time of charging the pellet is not controlled to the above-described temperature, it is particularly problematic if the pellet is charged into the smelting furnace in a short time so as not to affect the combustion and sintering. There is no.

  Now, in this embodiment, when processing the obtained pellets in a smelting furnace, the pellets are placed on the hearth of a smelting furnace having a metal hearth, and in that state A reduction heat treatment is performed. Thereby, it is possible to prevent the pellets after the reduction heat treatment from being fused to the hearth, and to suppress variation in nickel quality in the obtained metal. As a metal constituting the metal hearth, for example, nickel or cobalt can be used.

  Here, as the hearth of the smelting furnace, there is a method of spreading ceramics such as alumina or brick, or a carbonaceous reducing agent in addition to metals. However, when ceramics are used as the hearth of the smelting furnace, the wettability with the slag components in the pellets is high because both are oxides. Will progress. For this reason, the pellet cannot be separated from the hearth after the reduction reaction.

  In addition, in the method in which the carbonaceous reducing agent is spread and the pellet is reduced and heated on the carbonaceous reducing agent, the peeling after the completion of the reduction reaction can be easily performed. The reduction of iron will proceed. Then, the progress of the reduction changes depending on how the pellets and the carbonaceous reducing agent are in contact with each other, and it is difficult to control the degree of reduction. For example, when coal is spread as a carbonaceous reducing agent, when pellets are buried in about half of the coal, and when pellets and coal are in close contact with a point, the pellets are clearly buried in coal This causes a phenomenon in which the ratio of metallization of iron increases and the nickel quality in the metal produced in the pellet decreases. Thus, the nickel quality in the pellets varies, making it difficult to operate to obtain a stable product.

  As described above, the material of the metal hearth (hereinafter, also referred to as “flooring material”) is not limited as long as it is a metal or alloy that does not melt at the treatment temperature of the reduction treatment. For example, nickel or cobalt is used. Among them, nickel metal is particularly preferable among them.

FIG. 3 shows a metal Ellingham diagram. In the Ellingham diagram shown in FIG. 3, the one located at the top indicates that it is less likely to be reduced. For example, when metalizing iron, which is the main component in the pellet, if the processing temperature is 1300 ° C. (temperature line indicated by a dotted line in FIG. 3), the reduction of iron from divalent to zero or iron In the reduction of trivalent to divalent metal, a metal that is more easily oxidized causes substitution of oxygen with iron oxide, resulting in a phenomenon that the flooring material is oxidized and consumed. As shown in FIG. 3, for example, at a treatment temperature of 1300 ° C., the reaction of “4Fe ₂ O ₃ + O ₂ → 6Fe ₃ O ₄ ” cannot be avoided. It can be seen that lead, nickel, and cobalt can avoid substitution of oxygen with iron. In addition, since copper and lead have remarkably lower melting points than nickel, depending on the processing temperature conditions, there is a possibility of melting during the reduction reaction. In addition, since cobalt may start substitution of oxygen with iron from around 1200 ° C., for example, it is necessary to adjust the processing temperature condition more appropriately. For this reason, it is particularly preferable to use nickel metal as a flooring material among the metals described above.

  Further, in the nickel oxide ore smelting method according to the present embodiment, in this reduction step S2, reduction is performed at a temperature of 1000 ° C. or higher and 1300 or lower with pellets placed on a hearth made of metal such as nickel metal. A heat treatment is performed. As a result, the nickel quality in the obtained metal can be made as high as 4% or higher, and the recovery rate of nickel into the metal can be made as high as 90% or higher.

  When the reduction temperature in the reduction heat treatment is less than 1000 ° C., the reduction rate of nickel to metal becomes slow, and there arises a problem that the recovery rate of nickel becomes low within a practical operation time. Therefore, the lower limit of the reduction temperature is set to 1000 ° C. or higher.

  In addition, for example, if a reducing atmosphere is maintained with a carbonaceous reducing agent, carburization of a hearth metal, such as nickel metal, occurs, and this lowers the melting temperature of nickel used as the hearth metal to around 1330 ° C. If the temperature is higher than this, melting of the hearth metal occurs, and the pellet cannot be held. However, in actual operation, in order to prevent exhaustion of carbonaceous reductants such as coal contained in pellets due to leak air into the furnace, the burner is slightly incompletely burned, or carbonaceous reductants such as coal Therefore, it is inevitable that carbonaceous materials coexist and carburization of nickel, which is the hearth metal, is inevitable. Therefore, based on these conditions, considering the temperature variation in the furnace and the softening of the metal in the vicinity of the melting temperature, the upper limit value of the reduction temperature is preferably 1300 ° C. or less. Nickel grade metal can be produced.

  Here, FIG. 4 schematically shows the state of the reduction reaction in the pellets when the reduction heat treatment is performed in the reduction step S2. In the schematic diagram of FIG. 4, the symbol “10” indicates a metal hearth, the symbol “15” indicates a carbonaceous reducing agent contained in the pellet, and the symbol “20” indicates the pellet. Reference numeral “30” indicates a metal shell, reference numeral “40” indicates a metal grain, and reference numeral “50” indicates a semi-molten slag.

First, in the present embodiment, as described above, a smelting furnace having a metal hearth 10 is used, and pellets 20 are placed on the metal hearth 10 and reduced in that state. Start the heat treatment. In this reduction heat treatment, heat is transferred from the surface (surface layer portion) 20a of the pellet 20 and, for example, a reduction reaction as shown in the following reaction formula (i) proceeds based on the carbonaceous reducing agent 15 contained in the pellet 20 ( FIG. 4 (A)).
Fe ₂ O ₃ + C → Fe ₃ O ₄ + CO (i)

When the reduction in the surface layer portion 20a of the pellet 20 proceeds and the reduction to FeO proceeds (Fe ₃ O ₄ + C → FeO + CO), the replacement of nickel oxide (NiO) that has been combined as NiO—SiO ₂ with FeO is performed. In the surface layer portion 20a, the reduction of Ni as shown by the following reaction formula (ii) starts (FIG. 4B). Along with heat propagation from the outside, a reaction similar to this Ni reduction reaction gradually proceeds inside.
NiO + CO → Ni + CO ₂ (ii)

In this way, the reduction reaction of the iron oxide in the surface layer portion 20a of the pellet 20 along with the reduction reaction of the nickel oxide proceeds, for example, as shown in the following reaction formula (iii). In a short time, metallization proceeds in the surface layer portion 20a to become an iron-nickel alloy (ferronickel), and a metal shell (metal shell) 30 is formed (FIG. 4C). Since the metal shell 30 formed at this stage is thin and the CO / CO ₂ gas easily passes through, the reaction toward the inside gradually proceeds with the heat propagation from the outside.
FeO + CO → Fe + CO ₂ (iii)

  When the metal shell 30 in the surface layer portion 20a of the pellet 20 gradually becomes thick due to the progress of the reaction to the inside, the inside 20b of the pellet 20 is gradually filled with CO gas. Then, the reducing atmosphere in the inside 20b of the pellet 20 is increased, and the metallization of Ni and Fe proceeds to generate metal particles 40 (FIG. 4D). On the other hand, inside the metal shell 30, that is, inside 20b of the pellet 20, the slag component contained in the pellet 20 is gradually melted to generate a liquid phase (semi-molten state) slag 50.

When the carbonaceous reducing agent 15 contained in the pellet 20 is completely consumed, the metallization of Fe stops, and the non-metalized Fe remains in the form of FeO (partially Fe ₃ O ₄ ). The inner semi-molten slag 50 remains semi-molten or melts completely.

  In this manner, the metal particles 40 are recovered in a state of being dispersed in the melted slag 50, and an iron-nickel alloy can be obtained by separating the slag by a magnetic separation process or the like after a process such as pulverization.

  As described above, the carbonaceous reducing agent mixed in the pellet reduces the trivalent iron oxide to the divalent iron oxide, metalizes the nickel oxide, and further converts the divalent iron oxide into the metal. The metal shell and the metal grains can be formed.

  And in particular, in the method for smelting nickel oxide ore according to the present embodiment, a smelting furnace having a hearth made of metal such as nickel is used, and reduction is performed in a state where pellets are placed on the hearth made of metal. By performing the heat treatment, it is possible to prevent the pellets from being fused to the hearth after the treatment, and to suppress variation in nickel quality in the obtained metal.

  In addition, by setting the temperature of the reduction heat treatment performed in a state where the pellets are placed on the metal hearth in the range of 1000 ° C. or higher and 1300 ° C. or lower, the nickel quality in the obtained ferronickel metal is increased to 4% or higher. The quality can be improved, and the nickel recovery rate can be a high ratio of 90% or more.

  Further, the amount of carbonaceous reducing agent to be mixed in the pellet is a predetermined ratio, that is, the amount of carbonaceous reducing agent is 5% or more and 60% or less with respect to 100% of the total value of the chemical equivalents described above. In the reduction reaction, the total amount of iron oxide in the formed metal shell can be reduced without reducing the total amount of iron oxide in the reduction reaction. Thus, a part can be left as an oxide. Thus, ferronickel metal can be produced with a higher nickel quality and a higher nickel recovery rate in one pellet.

  Note that the slag in the pellets is in a semi-molten state or melted, but the separately formed metal and slag do not mix and are then mixed as separate phases of the metal solid phase and the slag solid phase by subsequent cooling. To become a mixture. The volume of this mixture has shrunk to a volume of about 50% to 60% as compared with the pellets to be charged.

<3. Separation process>
In the separation step S3, the metal and slag generated in the reduction step S2 are separated and the metal is recovered. Specifically, the metal phase is separated and recovered from the mixture containing the metal phase (metal solid phase) and the slag phase (slag solid phase containing a carbonaceous reducing agent) obtained by the reduction heat treatment on the pellets. As described above, the slag that has been melted by the reduction heat treatment into a liquid phase becomes a solid phase by cooling, and exists as a phase separate from the metal solid phase.

  As a method for 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, a method of separating a metal having a large particle diameter by sieving after crushing or pulverization, and a specific gravity It is possible to use a method such as separation by magnetic force or separation by magnetic force. The obtained metal phase and slag phase can be easily separated because of poor wettability.

  In this way, the metal phase is recovered by separating the metal phase and the slag phase.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to the following Examples at all.

[Example 1]
Nickel oxide ore as a raw material ore, a binder, and a carbonaceous reducing agent were mixed to obtain a mixture. The mixing amount of the carbonaceous reducing agent contained in the mixture is the chemical equivalent required to reduce nickel oxide contained in the formed pellets to nickel metal and ferric oxide contained in the pellets. When the total value of chemical equivalents required for reduction to metallic iron (total value of chemical equivalents) was 100%, the amount was 10% in terms of carbon content.

  Next, a spherical lump was formed by adding water appropriately to the obtained mixture of raw material powders and kneading by hand. Then, the pellets were dried by blowing hot air at 300 ° C. to 400 ° C. so that the solid content of the mass was about 70% by weight and the water content was about 30% by weight. (Diameter): 17 mm). Table 2 below shows the solid content composition of the pellets after the drying treatment.

  Next, in the smelting furnace, 25 manufactured pellets were placed on a dish-shaped hearth made of nickel metal and charged. The charging of the pellets into the smelting furnace was performed under a temperature condition of 600 ° C. At this time, in order to prevent oxidation due to leak air into the smelting furnace, coal powder (carbon content: 85% by weight, particle size: 0.0% by weight) corresponding to 10% by weight of the pellets. 4 mm) were allowed to coexist in the furnace.

  And reduction | restoration temperature was set to 1300 degreeC and the reduction heat processing was performed in the state which mounted the pellet on the hearth of nickel metal in the smelting furnace.

  Pellets were taken out from the furnace 5 minutes after the start of the reduction heat treatment. It was confirmed that it was cooled to 500 ° C. or less within 1 minute after taking out from the furnace.

  By such reduction heat treatment, an iron-nickel alloy (ferronickel metal) and slag were obtained. Table 3 below shows the nickel quality and iron quality of the obtained ferronickel metal. Calculated from the mass balance, the recovery rate of nickel into the metal (nickel recovery rate) was 90% or more.

[Example 2]
After the raw materials were mixed by the same method as in Example 1 to obtain a mixture, dry pellets were produced. At this time, in Example 2, the mixing amount of the carbonaceous reducing agent as a raw material was set to an amount that would be a ratio of 25% in terms of carbon to the total value of 100% of the chemical equivalents described above.

  Next, in the smelting furnace, 25 manufactured pellets were placed on a dish-shaped hearth made of nickel metal and charged. The charging of the pellets into the smelting furnace was performed under a temperature condition of 600 ° C. At this time, in order to prevent oxidation due to leak air into the smelting furnace, coal powder (carbon content: 85% by weight, particle size: 0.0% by weight) corresponding to 10% by weight of the pellets. 4 mm) were allowed to coexist in the furnace.

  And reduction | restoration temperature was 1000 degreeC and the reduction heat processing was performed in the state which mounted the pellet on the hearth of nickel metal in the smelting furnace.

  Pellets were taken out from the furnace 30 minutes after the start of the reduction heat treatment. It was confirmed that it was cooled to 500 ° C. or less within 1 minute after taking out from the furnace.

  By such a reduction heat treatment, ferronickel metal and slag were obtained. Table 4 below shows the nickel quality and iron quality of the obtained ferronickel metal. Calculated from the mass balance, the nickel recovery rate was 90% or more.

[Example 3]
After the raw materials were mixed by the same method as in Example 1 to obtain a mixture, dry pellets were produced. At this time, in Example 2, the mixing amount of the carbonaceous reducing agent as a raw material was set to an amount that would be a ratio of 25% in terms of carbon to the total value of 100% of the chemical equivalents described above.

  Next, in the smelting furnace, 25 manufactured pellets were placed on a dish-shaped hearth made of nickel metal and charged. The charging of the pellets into the smelting furnace was performed under a temperature condition of 600 ° C. At this time, in order to prevent oxidation due to leak air into the smelting furnace, coal powder (carbon content: 85% by weight, particle size: 0.0% by weight) corresponding to 10% by weight of the pellets. 4 mm) were allowed to coexist in the furnace.

  And reduction | restoration temperature was 1200 degreeC and the reductive heat processing was performed in the state which mounted the pellet on the hearth of nickel metal in the smelting furnace.

  Pellets were taken out from the furnace 10 minutes after the start of the reduction heat treatment. It was confirmed that it was cooled to 500 ° C. or less within 1 minute after taking out from the furnace.

  By such a reduction heat treatment, ferronickel metal and slag were obtained. Table 5 below shows the nickel quality and iron quality of the obtained ferronickel metal. Calculated from the mass balance, the nickel recovery rate was 90% or more.

[Comparative Example 1]
In the smelting furnace, the treatment was performed in the same manner as in Example 1 except that the reduction temperature was set to 1400 ° C. while the pellets were placed on the hearth of nickel metal.

  As a result, the nickel metal used for the hearth was melted, and all the pellets dropped during the reduction heat treatment, and the treatment could not be performed effectively.

[Comparative Example 2]
In the smelting furnace, the treatment was performed in the same manner as in Example 1 except that the reduction temperature was set to 800 ° C. while the pellets were placed on the hearth of nickel metal.

  As a result, although reduction heat treatment could be performed, the nickel recovery rate was very low at 20%.

10 Metal hearth 15 Carbonaceous reducing agent 20 Pellet 30 Metal shell (metal shell)
40 metal grains 50 slag

Claims (3)

A method for smelting nickel oxide ore to obtain an iron-nickel alloy by forming pellets from nickel oxide ore and reducing and heating the pellets,
A pellet manufacturing process for manufacturing pellets from the nickel oxide ore;
A reduction step of reducing and heating the obtained pellets in a smelting furnace,
In the pellet manufacturing process, at least the nickel oxide ore and a raw material containing a carbonaceous reducing agent are mixed to form a mixture, the mixture is agglomerated to form pellets,
In the reduction step, the pellets obtained in the pellet production step are placed on the hearth of a smelting furnace having a hearth made of nickel metal as a flooring material, and the temperature is 1000 ° C. or higher and 1300 ° C. or lower. A method for smelting nickel oxide ore, characterized by subjecting to a reduction heat treatment at temperature. The temperature at the time of charging the said pellet into the said smelting furnace shall be 600 degrees C or less. The smelting method of the nickel oxide ore of Claim 1 characterized by the above-mentioned. In the pellet manufacturing process, the chemical equivalent required to reduce nickel oxide contained in the formed pellet to nickel metal and the ferric oxide contained in the pellet are necessary to reduce to metallic iron. the sum of the chemical equivalent is 100% claim 1 or 2, characterized in that for adjusting the mixing amount of the carbonaceous reducing agent such that the amount of 5% to 60% or less of the carbon content The smelting method of the nickel oxide ore as described in 2.

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