JP2018178219A - Method for smelting oxide ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of enhancing a metal collection rate to improve productivity and capable of inexpensively, efficiently producing a high-quality metal in a smelting method for producing the metal by reducing a mixture including oxide ores such as nickel oxide ore.SOLUTION: There is provided a smelting method comprising mixing oxide ores with a carbonaceous reducer and reduction-treating the obtained mixture by heating to obtain a metal being a reducing substance and a slag. The method is characterized by reduction-treating the mixture in such a state that an oxidation inhibitor coexists. An oxide mixture, for example, having the oxide content of 90 mass% or more, or an oxidation-inhibiting mixture including the above oxide mixture and a carbonaceous reducer may be used as an oxidation-inhibiting material. The oxidation-inhibiting material, for example, may be made to coexist by placing on the upper face of the mixture, or may be made to coexist through surrounding the mixture thereby.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of smelting oxide ore, and more specifically, an oxide ore such as nickel oxide ore is mixed with a reducing agent and reduced under high temperature to obtain a metal-containing reduced ore. It relates to the smelting process.

  As a method of smelting nickel oxide ore called limonite or saprolite which is a kind of oxide ore, dry smelting method of producing nickel mat using smelting furnace, iron and nickel using rotary kiln or moving hearth furnace A dry smelting method of producing ferronickel which is an alloy of the above, a wet smelting method of producing mixed sulfide using an autoclave, and the like are known.

  Among the various methods described above, in particular, in the case of reducing and smelting nickel oxide ore using a dry smelting process, the nickel oxide ore of the raw material is crushed to a suitable size or the like in order to advance the reaction. Bulking is performed as pretreatment.

  Specifically, when the nickel oxide ore is agglomerated, that is, when the powder or fine ore is agglomerated, the nickel oxide ore is mixed with other components such as a reducing agent such as a binder or coke. The mixture is adjusted to moisture, etc., and then charged into a block making machine, for example, a block having a side or a diameter of about 10 mm to 30 mm (pellets, briquettes, etc.) It is common to assume.

  Pellets obtained by massing require a certain degree of air permeability in order to "fly" the contained water. Furthermore, if the reduction does not proceed uniformly in the pellet in the subsequent reduction treatment, the composition of the obtained reduced product becomes uneven, and disadvantages such as dispersion and uneven distribution of metal occur. Therefore, when producing a pellet, it is important to mix the mixture uniformly or to maintain the temperature as uniform as possible when reducing the obtained pellet.

  In addition, coarsening the metal (ferronickel) produced by the reduction treatment is also a very important technique. When the produced ferronickel has a fine size of, for example, several tens of μm to several hundreds of μm or less, it becomes difficult to separate from the slag that is produced simultaneously, and the recovery rate (yield) as ferronickel is greatly reduced. I will. Therefore, the process which coarsens the ferronickel after reduction is needed.

  Furthermore, how low the smelting cost can be kept is an important technical issue, and continuous processing that can be operated with compact equipment is desired.

  For example, Patent Document 1 discloses that particulates are produced by heating an agglomerate containing a metal oxide and a carbonaceous reducing agent and reducing and melting the metal oxide contained in the agglomerate to produce a particulate metal. A technique aimed at further enhancing productivity is disclosed. Specifically, granular materials obtained by supplying an agglomerate containing a metal oxide and a carbonaceous reducing agent onto the hearth of a moving bed reduction melting furnace and heating to reduce and melt the metal oxide are obtained. There is disclosed a method of producing particulate metal which is cooled and then discharged out of the furnace for recovery. And in this technique, the furnace temperature in the first half of the furnace for solid reduction of iron oxide in agglomerates is 1300 ° C. to 1450 ° C., and the furnace in which reduced iron in agglomerates is carburized, melted and agglomerated The furnace temperature in the second half region of the furnace is 1400 ° C. to 1550 ° C., and the maximum projected area ratio of the agglomerates to the hearth of the blast furnace when the distance between the agglomerates laid on the hearth is 0 When the relative density of the projected area ratio to the hearth of the agglomerates laid on the floor is the bed density, when heating the bed density of the agglomerates on the hearth to 0.5 or more and 0.8 or less, The method is characterized in that agglomerates having an average diameter of 19.5 mm or more and 32 mm or less are supplied onto the hearth, and according to such a method, by controlling the bed density and the average diameter of the agglomerates, It is said that the productivity of granular metallic iron can be improved.

  Certainly, it is considered that the productivity of granular metallic iron can be improved by controlling the bed density and the average diameter of agglomerates in comparison with the prior art proposed by the technology disclosed in Patent Document 1 mentioned above. Be However, this technique is strictly a technique for reactions outside the lumped organisms, and the most important factor in the reduction reaction is the state in the lumped organisms in which the reduction reaction takes place.

  That is, by controlling the reduction reaction in the lump organism, for example, the reaction efficiency can be further enhanced, and the reduction reaction can be uniformly generated, and it can be said that high quality metal can be produced. .

  Moreover, the yield at the time of manufacture of lumped organisms will fall by making the diameter of lumped organisms into the determined range like the technique disclosed by patent document 1, and cost will be increased. Furthermore, if the bed density of agglomerates is in the range of 0.5 to 0.8, it is not close-packed and, on the other hand, it is impossible to stack lumped organisms, resulting in a very inefficient treatment process, and the manufacturing cost Leads to the rise of

  Furthermore, in the process using the so-called total dissolution method in which all the raw materials are dissolved and reduced as in the technique disclosed in Patent Document 1, there is a big problem in terms of operation cost. For example, in order to completely melt the raw material nickel oxide ore, it is necessary to raise the temperature as high as 1500 ° C. or more, but such high temperature conditions require a lot of energy cost and use at such high temperature Furnaces are easily damaged, and repair costs also increase. Furthermore, since the raw material nickel oxide ore contains only about 1% of nickel, it is not necessary to recover other than iron corresponding to the nickel, but a large amount of components not necessary for recovery Will also melt everything and become extremely inefficient.

  Therefore, a partial dissolution reduction method has been considered, in which only necessary nickel is reduced preferentially to reduce iron contained in a much larger amount than nickel. However, in such a partial reduction method (also referred to as nickel preferential reduction method), in order to carry out the reduction reaction while maintaining the raw material in a semi-solid state which is not completely dissolved, while completely reducing nickel 100%, It is not easy to control the reaction so that iron reduction is limited to only a small part. As a result, partial reduction occurs in the reduction within the raw material, and there is a problem that efficient operation such as a reduction in nickel recovery rate is difficult.

  As described above, in mixing nickel oxide ore as a raw material and reducing the mixture to produce metal, there are many ways to produce high quality metal while improving the productivity and suppressing the production cost. There was a problem with

JP 2011-256414 A

  The present invention has been proposed in view of such circumstances, and in a smelting process for producing a metal by reducing a mixture containing an oxide ore such as nickel oxide ore, the productivity is improved by increasing the metal recovery rate. It is an object of the present invention to provide a method by which high quality metal can be manufactured inexpensively and efficiently.

  The present inventors diligently studied to solve the problems described above. As a result, it has been found that high-quality metals of high nickel quality can be efficiently produced by subjecting a mixture containing the raw material oxide ore to reduction treatment in the presence of an oxidation inhibitor, thereby completing the present invention. It reached.

  (1) According to the first aspect of the present invention, an oxide ore and a carbonaceous reductant are mixed, and the resulting mixture is heated and subjected to a reduction treatment to smelt the metal which is a reductant and slag. The method is a method of smelting oxide ore, wherein the mixture is subjected to reduction treatment in the coexistence of an oxidation inhibitor.

  (2) The second invention of the present invention is the method of smelting oxide ore according to the first invention, wherein an oxide mixture having an oxide content of 90% by mass or more is used as the oxidation inhibitor. .

  (3) In the third invention of the present invention according to the first invention, the oxidation inhibitor includes an oxide mixture having an oxide content of 90% by mass or more and a carbonaceous reductant as the oxidation inhibitor. It is a method of smelting oxide ore using a mixture.

  (4) The fourth invention of the present invention is the method for smelting oxide ore according to the third invention, wherein the carbonaceous reductant contained in the oxidation suppression mixture is coal and / or coke.

  (5) The fifth invention of the present invention is the method for smelting oxide ore according to any one of the first to fourth inventions, wherein the oxidation inhibitor is placed on the upper surface of the mixture and subjected to reduction treatment.

  (6) The sixth invention of the present invention is the method for smelting oxide ore according to any one of the first to fourth inventions, wherein the mixture is surrounded by the oxidation inhibitor and subjected to reduction treatment.

  (7) The seventh invention of the present invention is the method of smelting oxide ore according to any one of the first to sixth inventions, wherein ash of the carbonaceous reducing agent is used at least in part as the oxidation inhibitor. It is.

  (8) In the eighth invention of the present invention according to any one of the first to seventh inventions, at least a portion of one or more selected from coal ash, charcoal ash, and bamboo charcoal ash as the oxidation inhibitor. It is a method of smelting oxide ore used.

  (9) In the ninth invention according to any one of the first to sixth inventions, the oxidation inhibitor is selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite. It is a method of smelting oxide ore using at least one of one or more of the following.

  (10) The tenth invention of the present invention is the method for smelting oxide ore according to any one of the first to ninth inventions, wherein the reduction temperature in the reduction treatment is set to 1200 ° C. or more and 1450 ° C. or less.

  (11) The eleventh invention of the present invention is the method for smelting oxide ore according to any one of the first to tenth inventions, wherein said oxide ore is nickel oxide ore.

  (12) The twelfth invention of the present invention is the method for smelting oxide ore according to any of the first to eleventh inventions, wherein said metal is ferronickel.

  According to the present invention, in a smelting process for producing a metal by reducing a mixture containing an oxide ore such as nickel oxide ore, a metal recovery rate is increased to improve productivity, and high quality metal can be made inexpensive. And it can manufacture efficiently.

It is process drawing which shows an example of the flow of the smelting method of a nickel oxide ore. It is a figure which shows typically the state when the oxidation inhibitor is put and coexisted on the upper surface (upper surface) of the mixture to be subjected to reduction treatment. It is a figure which shows typically the state when the mixture to be subjected to reduction treatment is made to coexist by being surrounded by an oxidation inhibitor.

  Hereinafter, specific embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. 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. Moreover, in this specification, the expression with "X-Y" (X and Y are arbitrary numerical values) is the meaning of "X or more and Y or less".

<< 1. Outline of the Invention >>
In the method of smelting oxide ore according to the present invention, the oxide ore and the carbonaceous reductant are mixed by using the oxide ore as a raw material to form a mixture, and the obtained mixture is subjected to reduction treatment under high temperature to be a reduced product Is a method of manufacturing metal. For example, a nickel oxide ore containing nickel oxide or iron oxide is used as a raw material as an oxide ore, and the nickel oxide ore is mixed with a carbonaceous reducing agent to preferentially reduce nickel contained in the mixture at high temperatures. And a method of producing ferronickel which is an alloy of iron and nickel by partially reducing iron.

  Specifically, in the method of smelting oxide ore according to the present invention, the oxide ore and the carbonaceous reducing agent are mixed, and the obtained mixture is heated as a raw material and subjected to reduction treatment, and the metal which is a reduced product A method of obtaining slag is characterized in that the mixture is subjected to reduction treatment in the state where an oxidation inhibitor coexists.

  According to such a smelting and refining method, the oxidation treatment in the mixture is effectively suppressed by subjecting the mixture containing the oxide ore and the carbonaceous reducing agent to a reduction treatment in the state where the oxidation inhibitor coexists. It is possible to increase the metalization rate of nickel and the like, and to manufacture high quality metal of high metal grade such as nickel. Moreover, since it is a simple method of making an oxidation inhibitor coexist, it can process cheaply and efficiently.

In the following, as a specific embodiment of the present invention (hereinafter referred to as "the present embodiment"), a method of smelting nickel oxide ore will be described as an example. As mentioned above, the nickel oxide ore which is a smelting raw material contains at least nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ), and the reduction treatment is carried out using the nickel oxide ore as a smelting raw material. By doing this, an iron-nickel alloy (ferronickel) can be produced as a metal.

  The present invention is not limited to nickel oxide ore as the oxide ore, and the refining method is not limited to the method of producing ferronickel from nickel oxide ore including nickel oxide and the like.

<< 2. Method of smelting nickel oxide ore >>
In the method of smelting nickel oxide ore according to the present embodiment, the nickel oxide ore is mixed with a carbonaceous reductant to form a mixture, and the mixture is subjected to reduction treatment to obtain ferronickel as a metal as a reductant. And slag. In addition, ferronickel which is a metal can be collect | recovered by isolate | separating the metal from the mixture containing the metal and slag which were obtained through reduction process.

  FIG. 1: is process drawing which shows an example of the flow of the smelting method of a nickel oxide ore. As shown in FIG. 1, this smelting process comprises a mixing process step S1 of mixing raw materials containing nickel oxide ore, a mixture forming step S2 of forming the obtained mixture into a predetermined shape, and a formed mixture ( It has a reduction step S3 of reducing and heating the pellet at a predetermined reduction temperature, and a separation step S4 of separating the metal and slag generated in the reduction step S3 and recovering the metal.

<2-1. Mixed treatment process>
The mixing treatment step S1 is a step of mixing raw material powders containing nickel oxide ore to obtain a mixture. Specifically, in the mixing treatment step S1, a carbonaceous reducing agent is added to and mixed with the raw material ore, nickel oxide ore, and iron ore, a flux component, a binder, etc., as an additive of an optional component, for example Powders having a particle size of about 0.1 mm to 0.8 mm are added and mixed to obtain a mixture. The mixing process can be performed using a mixer or the like.

The nickel oxide ore, which is a raw material ore, is not particularly limited, and limonite ore, saprolite ore, etc. can be used. The nickel oxide ore contains at least nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ).

  The carbonaceous reducing agent is not particularly limited, and examples thereof include coal powder, coke powder and the like. The carbonaceous reducing agent is preferably of the same size as the particle size or particle size distribution of the raw material ore, nickel oxide ore, since it is easy to mix uniformly and the reduction reaction is easily uniform, which is preferable.

  As the mixing amount of the carbonaceous reductant, it is necessary to reduce the total amount of nickel oxide constituting the nickel oxide ore to nickel metal, and the chemical equivalent necessary to reduce iron oxide (ferric oxide) to metallic iron. The ratio of the carbon amount is preferably 5% by mass or more and 60% by mass or less, more preferably, when the total value with both chemical equivalents (also referred to as “total value of chemical equivalents” for convenience) is 100% by mass. It can adjust so that it may become a ratio of the amount of carbon of 10 mass% or more and 40 mass% or less. Thus, by setting the mixing amount of the carbonaceous reducing agent to a ratio of 5% by mass or more based on 100% by mass of the total value of the chemical equivalents, the reduction of nickel can be efficiently advanced, and the productivity is improves. On the other hand, by setting the ratio of 60 mass% or less to the total value 100 mass% of chemical equivalents, the reduction amount of iron can be suppressed, the deterioration of nickel grade can be prevented, and high quality ferronickel can be manufactured. it can. Thus, preferably, the mixing amount of the carbonaceous reducing agent is a ratio of the carbon amount of 5% by mass to 60% by mass with respect to 100% by mass of the total value of the chemical equivalents, and the metal component on the surface of the mixture The shell (metal shell) thus produced can be uniformly generated to improve the productivity, and high quality ferronickel of high nickel grade can be obtained, which is preferable.

  Moreover, as iron ore which is an additive of an optional component, for example, iron ore having an iron grade of about 50% or more, hematite obtained by wet refining of nickel oxide ore, and the like can be used.

  Moreover, as a flux component, calcium oxide, calcium hydroxide, calcium carbonate, silicon dioxide etc. can be mentioned, for example. Moreover, as a binder, bentonite, polysaccharides, resin, water glass, a dehydration cake etc. can be mentioned, for example.

  In the mixing treatment step S1, a mixture is obtained by uniformly mixing the raw material powder containing the nickel oxide ore as described above. At the time of this mixing, kneading may be performed simultaneously in order to improve the mixing property, or may be performed after mixing. Specifically, kneading can be carried out using, for example, a twin-screw kneader, and the mixture is kneaded to apply a shearing force to the mixture to break the aggregation of the carbonaceous reductant, the raw material powder, etc. to be uniform. And improve the adhesion of each particle and reduce the voids. As a result, the reduction reaction easily occurs and can be reacted uniformly, and the reaction time of the reduction reaction can be shortened. In addition, variations in quality can be suppressed. And as a result, highly productive processing can be given and high quality ferronickel can be manufactured.

  Moreover, after kneading, you may extrude using an extruder. By extruding in this manner, a higher kneading effect can be obtained.

  In addition, although an example of a composition (weight%) of a one part raw material powder mixed in mixing treatment process S1 is shown in following Table 1, as a composition of a raw material powder, it is not limited to this.

2-2. Mixture molding process>
The mixture forming step S2 is a step of forming the mixture obtained in the mixing step S1. Specifically, the mixture obtained by mixing the raw material powder is formed into a mass (mass, hereinafter also referred to as "pellet") of a certain size or more. Therefore, mixture formation process S2 can be put in another way also as a pellet manufacturing process.

  The forming method is not particularly limited, but an amount of water necessary to form a mass of the mixture is added, for example, a mass production apparatus (a rolling granulator, a compression molding machine, an extrusion molding machine, etc. or a pelletizer) It is molded into pellets of a predetermined shape using

  As a shape of the lump thing (pellet) obtained by shape | molding a mixture, it can be set as rectangular solid shape, cylindrical shape, spherical shape etc., for example. With such a shape, the mixture can be easily formed, and the cost for forming can be suppressed. In addition, since the above-described shape is a simple shape and not complicated, the generation of defective products can be suppressed, and the quality of the obtained pellets can be made uniform.

  Moreover, as the shape of the agglomerate, it is preferable that the pellet can be treated in a laminated state in the treatment in the subsequent reduction step, and in that respect as well, if the pellet is rectangular, cylindrical, spherical or the like, It is easy to stack and place in the reduction furnace, and the amount of treatment to be provided for the reduction treatment can be increased. In addition, by stacking in this way and subjecting to reduction treatment, the processing amount at the time of reduction can be increased without making one pellet large, so handling becomes easy, and it also falls off during movement, etc. And the occurrence of defects etc. can be suppressed.

The volume of the formed mixture (pellet) is not particularly limited, but is preferably 8000 mm ³ or more. If the volume of the pellet is too small, the molding cost will be high, and it will take time to put it into the reduction furnace. In addition, when the volume of the pellet is small, the ratio of the surface area to the whole pellet becomes large, so the difference between the reduction degree on the surface and the inside of the pellet tends to appear, and it may be difficult to promote the reduction uniformly. It becomes difficult to produce high quality ferronickel. On the other hand, if the volume of the pellet made of the mixture is 8000 mm ³ or more, the molding cost can be effectively suppressed and the handling becomes easy. In addition, high quality Fell nickel can be stably obtained.

  After the mixture is formed, the mixture may be subjected to a drying treatment. The mixture may contain a predetermined amount of water, and there is a concern that the mixture may be shattered if the internal water is vaporized and expanded at once due to a rapid temperature rise during reduction treatment. From the viewpoint of preventing such expansion, a step of drying the formed mixture can be provided.

  Specifically, in the drying treatment, for example, the treatment can be performed so that the solid content of the pellet is about 70% by weight and the water content is about 30% by weight. For example, hot air of 150 ° C. to 400 ° C. is blown onto the pellets to dry them.

  In the case of relatively large pellets, the mixture before and / or after the drying process may have cracks or cracks. When the lump is large, even if the surface area is increased due to cracking or the like, the influence is small and does not become a major problem. Therefore, there is no particular problem even if there is a crack or the like in the molded pellet to be subjected to the reduction treatment.

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

<2-3. Reduction process>
In the reduction step S3, the mixture formed through the mixture forming step S2 is charged into a reduction furnace, and reduction heating is performed at a predetermined reduction temperature. By the reduction heat treatment in the reduction step S3, the smelting reaction (reduction reaction) proceeds to generate metal and slag which are reductants.

  In the reduction step S3, the slag in the mixture is melted to form a liquid phase, but the metal that has already been separated and generated by the reduction treatment and the slag do not mix, and the metal solid phase is obtained by subsequent cooling. It becomes a mixture mixed as a separate phase with the slag solid phase. The volume of this mixture is shrunk to a volume of about 50% to 60% as compared to the mixture to be charged.

  In the reduction step S3, when the mixture is charged into the reduction furnace, the hearth of the reduction furnace is previously covered with a carbonaceous reductant (hereinafter, also referred to as "furnace carbonaceous reductant"), The mixture may be placed on top of the hearth carbonaceous reductant for processing. In addition, a floor covering material such as alumina, zirconia, magnesia or the like may be placed on the hearth, and the mixture may be placed thereon for processing. In addition, as a floor covering material, what has an oxide as a main component can be used.

  As described above, the carbonaceous reductant, the floor covering material, etc. are placed on the hearth of the reduction furnace, and the mixture is placed thereon for reduction treatment, thereby suppressing the direct reaction between the hearth and the mixture. While preventing fusion to the hearth, the life of the hearth can be extended.

  Now, the present embodiment is characterized in that the mixture charged in the reduction furnace is subjected to the reduction treatment in the state where the oxidation inhibitor coexists. Thus, by performing reduction treatment on the mixture in the state where the oxidation inhibitors coexist, oxidation inside the mixture can be effectively suppressed, and the metallization rate of nickel is improved. , High quality nickel of high quality ferronickel can be obtained efficiently.

  More specifically, for example, a heavy oil combustion atmosphere usually contains several percent of oxygen. Therefore, the reduced mixture may be oxidized to become oxide again. Thus, if the oxidation of the mixture proceeds, the reduction ratio of the raw material ore decreases, and the oxidation of nickel, which is more easily oxidized than iron, progresses, and the nickel content (nickel grade) in the obtained ferronickel decreases. I will.

  On the other hand, the reduction of the mixture in the presence of the oxidation inhibitor can prevent the entry of oxygen contained in the atmosphere into the mixture. In particular, since oxidation proceeds from the surface of the mixture, the oxidation inhibitor is allowed to coexist in the reduction furnace, and in particular, the oxidation inhibitor is effectively adhered to the surface of the mixture, thereby preventing oxidation effectively. It is possible to suppress the reduction of the reduction rate and the reduction of the grade of nickel in ferronickel based thereon.

  As the oxidation inhibitor, for example, an oxide mixture having a composition in which the content of the oxide is 90% by mass or more can be used. Thus, by using an oxide mixture containing a high proportion of oxides as an oxidation inhibitor, it is possible to effectively prevent the entry of oxygen into the mixture, and to suppress oxidation more efficiently. it can.

  Moreover, the mixture which made the oxide mixture of the composition whose content of an oxide is 90 mass% or more, and a carbonaceous reducing agent can also be used as an oxidation inhibitor. In addition, this mixture is called "an oxidation suppression mixture." The carbonaceous reductant contained in the oxidation suppression mixture is preferably at least one or more of coal and coke. At this time, as the oxidation suppressing mixture, it is preferable that the weight ratio of the oxidation mixture: carbonaceous reducing agent = 9: 1, that is, the content of the carbonaceous reducing agent be about 10%.

  Thus, by using an oxidation suppression mixture containing a high proportion of oxides as an oxidation inhibitor and further containing coal and coke, it is possible to prevent the entry of oxygen into the mixture, and at the same time, it is possible to It can be removed actively. Further, even if oxygen is present in the vicinity of the mixture, the presence of coal or coke causes them to react with the oxygen to suppress the oxidation of the mixture. Also, even if oxidation of the mixture has progressed, the mixture can be reduced again by the presence of coal and coke in the vicinity of the mixture.

  Moreover, as the oxidation inhibitor, it is preferable to use at least a part of the ash obtained by the carbonaceous reductant that constitutes the mixture together with the raw material nickel oxide ore. Moreover, it is preferable to use at least one type or more selected from coal ash, charcoal ash, and bamboo charcoal ash as an oxidation inhibitor. These are mainly oxides (oxide mixtures having an oxide content of 90% by mass), and oxidation can be effectively suppressed by making them coexist around the mixture to be subjected to reduction treatment .

  Moreover, as an oxidation inhibitor, at least one type selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite can also be used at least in part. These are oxide mixtures having an oxide content of 90% by mass, and oxidation can be effectively suppressed by coexisting around the mixture to be subjected to the reduction treatment. In addition, even if oxidation of the mixture proceeds, it also has the effect of reducing the mixture again.

  Here, the state in which the oxidation inhibitor coexists can be, for example, a state in which the oxidation inhibitor 11 is placed on the upper surface (upper surface) of the mixture 10 as schematically shown in FIG. 2 as an example. . As described above, since the oxidation of the mixture proceeds from the surface, the mixture 10 can be thus obtained by placing the oxidation inhibitor 11 on the “surface” of the mixture 10 and keeping the mixture in contact with the surface. Can be effectively suppressed. In addition, the code | symbol 20 in FIG. 2 shows the hearth of a reduction furnace, The code | symbol 21 shows the bed covering material (Carbon reducing agents, such as coal, floor covering materials, such as an alumina, a zirconia, magnesia, etc.) spread on a hearth (The same applies to FIG. 3).

  Since it is sufficient to prevent the contact between oxygen and metal on the surface of the mixture, it is possible to effectively suppress the oxidation of the mixture as long as the oxidation inhibitor is present even in a part where the combustion gas etc. directly strikes. it can. In particular, when the reduction furnace is heated by a burner, the burner is often installed on the upper side of the object to be treated as a suitable place for equipment, and therefore, a gas containing a relatively large amount of oxygen is supplied from the upper side It will be done. For this reason, as shown in FIG. 2, it is possible to exhibit an effective oxidation suppressing effect by causing the oxidation inhibitor to be present on the surface of the mixture, particularly on the upper surface thereof, which is preferable. .

  In addition, as a state in which the oxidation inhibitor coexists, for example, as schematically shown in FIG. 3, the mixture 10 is surrounded by the oxidation inhibitor 11 so that the surface of the mixture 10 is not exposed. It can be in the state. In addition, the mixture 10 can also be expressed as "filling" inside the lump of the oxidation inhibitor 11. In this way, by burying the mixture 10 in the oxidation inhibitor 11 and surrounding it for reduction treatment, it is possible to construct a wall for so-called oxidation prevention, and it is more effective to make the penetration of oxygen into the mixture 10 more effective. Can be prevented, and oxidation can be further suppressed.

  In addition, as a specific aspect of the state in which an oxidation inhibitor coexists, it is not restricted to what was shown in FIG.2 and FIG.3, but it is an aspect which can prevent oxidation from entering the mixture and suppress oxidation efficiently. What is necessary is just to select the method according to the situation.

  The reduction furnace used for the reduction heat treatment is not particularly limited, but it is preferable to use, for example, a moving hearth furnace. By using a moving hearth furnace as the reduction furnace, the reduction reaction proceeds continuously, and the reaction can be completed in one facility, and the processing temperature is higher than that in each step using a separate furnace. Control can be performed precisely.

  In addition, the use of a mobile hearth furnace can reduce the heat loss between the processes and enable more efficient operation. That is, when the reaction is performed using different furnaces, the temperature is temporarily lowered by exposing the container in which the mixture is sealed to the outside air or a state close to it when moving the furnace between the furnaces. As a result, heat loss occurs and the reaction atmosphere changes. As a result, the reaction does not start immediately upon recharging to the furnace for the next treatment.

  On the other hand, by performing each processing with one facility using a moving hearth furnace, the heat loss can be reduced and the atmosphere in the furnace can be properly controlled, so that the reaction can progress more effectively. it can. As a result, it is possible to more effectively obtain high quality ferronickel having high nickel quality.

  Specifically, as the moving hearth furnace, for example, a rotary hearth furnace which is circular and divided into a plurality of processing regions can be used. In the rotary hearth furnace, each processing is performed in each area while rotating in a predetermined direction. In this rotary hearth furnace, the processing time in each region can be adjusted by controlling the time (moving time, rotation time) when passing through each region, and the rotary hearth furnace makes one rotation. Every time the mixture is smelted. Moreover, as a mobile hearth furnace, a roller hearth kiln etc. may be sufficient.

  In reduction processing using a reduction furnace, nickel oxide contained in the raw material ore, nickel oxide ore, is reduced as completely as possible, while iron oxide contained in the nickel oxide ore is only partially reduced Then, so-called partial reduction is carried out to obtain the target high nickel grade ferronickel.

  The reduction temperature is not particularly limited, but is preferably in the range of 1200 ° C. or more and 1450 ° C. or less, and more preferably in the range of 1300 ° C. or more and 1400 ° C. or less. By reducing in such a temperature range, a reduction reaction can be uniformly generated, and a metal (ferronickel) with suppressed variation in quality can be generated. Further, more preferably, reduction at a reduction temperature in the range of 1300 ° C. or more and 1400 ° C. or less can generate a desired reduction reaction in a relatively short time.

  In the reduction treatment, the internal temperature of the reduction furnace is raised by a burner or the like until the reduction temperature in the above-mentioned range is reached, and the temperature is maintained after the temperature rise.

<2-4. Separation process>
In the separation step S4, the metal generated in the reduction step S3 and the slag are separated to recover the metal. Specifically, the metal phase is separated and recovered from a mixture (mixture) including the metal phase (metal solid phase) and the slag phase (slag solid phase) obtained by reduction heat treatment on the mixture.

  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, separation by specific gravity, separation by magnetic force, etc. in addition to removal of unnecessary substances by sieving You can use the method of

  Further, the metal phase and the slag phase obtained can be easily separated due to poor wettability, and for example, a predetermined height difference with respect to a large inclusion obtained by the treatment in the reduction step S3 described above. The metal phase and the slag phase can be easily separated from the mixture by providing an impact such as dropping the sample or applying a predetermined vibration at the time of sieving.

  By separating the metal phase and the slag phase in this manner, the metal phase is recovered.

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

«Example 1 to Example 60»
[Mixing process]
Nickel oxide ore as raw material ore, iron ore, silica sand and limestone which are flux components, binder, and carbonaceous reductant (coal powder, carbon content: 85% by weight, average particle size: about 90 μm) The mixture was mixed using a mixer while adding water to obtain a mixture. The carbonaceous reductant is the total value of the amount necessary to reduce nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ) contained in the raw material ore, nickel oxide ore, to 100% by mass. When contained, in a proportion of 25%.

[Mixing process]
Next, the obtained mixture was granulated using a pan granulator and sieved to a size of φ15.5 ± 1.0 mm. Thereafter, the sieved sample is evenly divided into 60 pieces to obtain a mixture sample to be subjected to reduction treatment in the reduction step.

[Reduction process]
Using the prepared mixture sample, reduction treatment was performed under the conditions shown in Tables 4 to 6 below. Specifically, the mixture sample was charged into a reduction furnace, and in the state where specific oxidation inhibitors coexist, reduction heat treatment was performed at each reduction temperature and reduction time. In addition, the hearth of the reduction furnace is previously covered with “ash” containing SiO _{2 as} the main component and small amounts of oxides such as Al ₂ O ₃ and MgO as other components, and the mixture sample is placed thereon It was placed and processed.

  Each mixture sample was subjected to a drying treatment by blowing hot air at 170 ° C. to 250 ° C. so that the solid content was about 70 wt% and the water content was about 30 wt% before the reduction treatment. The solid composition (excluding carbon) of the sample after the drying treatment is shown in Table 3 below.

  Here, as the oxidation inhibitor, coal ash, charcoal ash, bamboo charcoal ash, alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite were selected and used in each example.

  In addition, as the coexistence state of the oxidation inhibitor (in the table, “How to place the oxidation inhibitor”), as shown in FIG. 2, an embodiment in which the oxidation inhibitor is placed on the upper surface of the mixture (table Among them, it is one of “glowing”) or a mode (described as “filling” in the table) in which the mixture is embedded in the oxidation inhibitor and the surface is not visible as illustrated in FIG.

«Comparative Example 1 to Comparative Example 3»
In Comparative Examples 1 to 3, a mixture sample was prepared in the same manner as in the example, and the mixture sample was charged into a reduction furnace and subjected to reduction heat treatment, but at this time, the oxidation inhibitor was not used. It was processed. The reduction temperature and the reduction time were in the same range as in the example.

«Evaluation»
The nickel metal ratio and the nickel content in the metal of the samples taken out after the reduction heat treatment were analyzed and calculated using an ICP emission spectrophotometer (SHIMAZU S-8100 type). Tables 4 to 6 below also show values calculated from the analysis results. In addition, the nickel metal ratio was calculated | required by (1) Formula and the nickel content rate in metal by (2) Formula.
Nickel metal ratio = amount of metallized Ni in the mixture ÷ (amount of all Ni in the pellet) x 100 (%) · · · (1) Nickel content in metal = amount of metallized Ni in the mixture ÷ (total amount of metalized Ni and Fe in the pellet) × 100 (%) (2)

In addition, after each sample collected was pulverized by wet treatment, metal was recovered by magnetic separation. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the content ratio of Ni therein, and the amount of recovered Ni. The Ni metal recovery rate was determined by equation (3).
Recovery rate of Ni metal = amount of recovered Ni ÷ (amount of input ore × content ratio of Ni in ore) × 100 (3)

  As shown in the results of Tables 4 to 6, in Examples 1 to 60 in which the mixture sample was subjected to reduction treatment in the state in which the oxidation inhibitor coexisted, the nickel metallization ratio, the nickel content in metal, and the metal recovery ratio The values were all high, and good results were obtained. It is considered that this is because oxygen was prevented from entering the inside of the mixture by being subjected to the reduction treatment in the state of coexistence of the oxidation inhibitor, and oxidation could be effectively suppressed.

  On the other hand, in Comparative Examples 1 to 3 in which the oxidation inhibitor was not used, the nickel metalization ratio was 85.0% to 85.5%, although the other reduction treatment conditions were equivalent. The nickel content in the metal was 14.2% to 14.6%, and the metal recovery rate was 75.0% to 75.8%, which were clearly lower than those in Examples.

  From the above results, it has been found that a nickel-containing metal can be obtained with high efficiency by performing reduction treatment on a mixture containing the raw material nickel oxide ore in the state in which the oxidation inhibitor coexists.

«Example 61 to Example 120»
[Mixing process]
Nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux component, binder, and carbonaceous reductant (coal powder, carbon content: 85% by weight, average particle size: about 83 μm), appropriate amounts The mixture was mixed using a mixer while adding water to obtain a mixture. The carbonaceous reductant is the total value of the amount necessary to reduce nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ) contained in the raw material ore, nickel oxide ore, to 100% by mass. When contained, in a proportion of 27%.

[Mixing process]
Next, the obtained mixture was granulated using a pan granulator and sieved to a size of φ14.5 ± 1.0 mm. Thereafter, the sieved sample was divided into 60 pieces to obtain a mixture sample to be subjected to reduction treatment in the reduction step.

[Reduction process]
Using the prepared mixture sample, reduction treatment was performed under the conditions shown in Tables 7 to 11 below. Specifically, the mixture sample was charged into a reduction furnace, and in the state where specific oxidation inhibitors coexist, reduction heat treatment was performed at each reduction temperature and reduction time. In addition, the hearth of the reduction furnace is previously covered with “ash” containing SiO _{2 as} the main component and small amounts of oxides such as Al ₂ O ₃ and MgO as other components, and the mixture sample is placed thereon It was placed and processed.

  Each mixture sample was subjected to a drying treatment by blowing hot air at 170 ° C. to 250 ° C. so that the solid content was about 70 wt% and the water content was about 30 wt% before the reduction treatment. The solid content composition of the sample after the drying treatment was the same as in Table 3 above.

  Here, as the oxidation inhibitor, an oxidation suppression mixture in which an oxide mixture having an oxide content of 90% by mass or more and coal as a carbonaceous reductant were mixed was used. The oxide mixture was selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite in each example. In addition, in the oxidation suppression mixture, the mixing ratio of the oxide mixture and the coal was 9: 1 by weight ratio.

  In addition, as the coexistence state of the oxidation inhibitor (in the table, “How to place the oxidation inhibitor”), as shown in FIG. 2, an embodiment in which the oxidation inhibitor is placed on the upper surface of the mixture (table Among them, it is one of “glowing”) or a mode (described as “filling” in the table) in which the mixture is embedded in the oxidation inhibitor and the surface is not visible as illustrated in FIG.

«Evaluation»
The nickel metal ratio and the nickel content ratio in the metal were determined for the samples taken out after the reduction heat treatment. Further, after each sample collected was pulverized by wet treatment, metal was recovered by magnetic separation to calculate a Ni metal recovery rate. Tables 7 to 11 below also show values calculated from the analysis results.

  As shown in the results of Tables 7 to 11, by subjecting the mixture sample to a reduction treatment in the presence of an oxidation inhibitor consisting of an oxidation inhibition mixture, the nickel metallization ratio, the nickel content in metal, and the metal recovery ratio are obtained. Both values were high, and good results were obtained. In particular, the nickel metallizing ratio was stably high at 94% or more as compared with Examples 1 to 60.

10 mixture 11 oxidation inhibitor 20 hearth of reduction furnace 21 bed material

Claims (12)

The method is a smelting method in which an oxide ore and a carbonaceous reductant are mixed, and the obtained mixture is heated and subjected to a reduction treatment to obtain a metal as a reductant and slag.
A method of smelting oxide ore, wherein the mixture is subjected to reduction treatment in the presence of an oxidation inhibitor. The method for smelting oxide ore according to claim 1, wherein an oxide mixture having an oxide content of 90% by mass or more is used as the oxidation inhibitor. The method for smelting oxide ore according to claim 1, wherein an oxidation suppression mixture containing an oxide mixture having an oxide content of 90% by mass or more and a carbonaceous reduct is used as the oxidation inhibitor. The method for smelting oxide ore according to claim 3, wherein the carbonaceous reductant contained in the oxidation suppression mixture is coal and / or coke. The method for smelting oxide ore according to any one of claims 1 to 4, wherein the oxidation inhibitor is placed on the upper surface of the mixture and subjected to reduction treatment. The method for smelting oxide ore according to any one of claims 1 to 4, wherein the mixture is surrounded by the oxidation inhibitor and subjected to reduction treatment. The method for smelting oxide ore according to any one of claims 1 to 6, wherein ash of the carbonaceous reducing agent is used at least in part as the oxidation inhibitor. The method for smelting oxide ore according to any one of claims 1 to 7, wherein one or more types selected from coal ash, charcoal ash, and bamboo charcoal ash are used at least in part as the oxidation inhibitor. The oxide ore according to any one of claims 1 to 6, wherein one or more types selected from alumina, alumina cement, magnesia, magmesia cement, zirconia, zirconia cement, and mullite are used as at least a part of the oxidation inhibitor. Smelting method. The method for smelting oxide ore according to any one of claims 1 to 9, wherein a reduction temperature in the reduction treatment is set to 1200 ° C or more and 1450 ° C or less. The method for smelting oxide ore according to any one of claims 1 to 10, wherein the oxide ore is nickel oxide ore. The method for smelting oxide ore according to any one of claims 1 to 11, wherein the metal is ferronickel.

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