JP7285423B2 - Method for smelting oxide ore - Google Patents

Description

TECHNICAL FIELD The present invention relates to a smelting method for oxide ore, and for example, to a smelting method for obtaining a reduced product by reducing oxide ore such as nickel oxide ore as a raw material with a carbonaceous reducing agent.

Nickel oxide ore called limonite or saprolite, which is a type of oxide ore, is smelted using a pyrometallurgical method that uses a smelting furnace to produce nickel matte, a rotary kiln or a moving hearth furnace that uses iron and nickel. A pyrometallurgical refining method to produce an alloy of iron and nickel (an alloy of iron and nickel is hereinafter referred to as "ferronickel"). ) are known.

Among the various methods described above, when the nickel oxide ore is reduced and smelted using the pyrometallurgical method, the raw material nickel oxide ore is crushed to an appropriate size in order to proceed with the reaction. Agglomeration processing is performed as a pretreatment.

Specifically, when the nickel oxide ore is agglomerated, that is, when powdery or fine-grained ore is agglomerated, the nickel oxide ore and other components such as a binder and a reducing agent such as coke are mixed. After adjusting the moisture content, etc., the mixture is charged into a lump manufacturing machine, for example, a molded product (pellets, briquettes, etc.) having a side or a diameter of about 10 mm or more and 30 mm or less. Hereinafter, simply “pellets” It is common to assume that

Pellets obtained by agglomeration require a certain degree of air permeability in order to "fly off" the contained moisture. Furthermore, in the subsequent reduction treatment, if the reduction does not proceed uniformly within the pellet, the composition of the resulting reduced product becomes non-uniform, causing problems such as dispersion or uneven distribution of the metal. Therefore, it is important to uniformly mix the mixture when producing pellets, and to maintain as uniform a temperature as possible when reducing the obtained pellets.

In addition, coarsening the metal (ferronickel) produced by the reduction treatment is also a very important technique. If the generated ferronickel has a fine size of, for example, several tens of micrometers or more and several hundred micrometers or less, it becomes difficult to separate it from the slag that is generated at the same time, and the recovery rate (yield) as ferronickel is greatly reduced. put away. Therefore, a treatment for coarsening ferronickel after reduction is required.

For example, in Patent Document 1, an agglomerate containing a metal oxide and a carbonaceous reducing agent is supplied onto the hearth of a moving bed type reduction melting furnace and heated to reduce and melt the metal oxide. In the manufacturing method, when the relative value of the projected area ratio of the agglomerate to the hearth with respect to the maximum projected area ratio of the agglomerate to the hearth when the distance between the agglomerates is 0 is taken as the laying density , a method of supplying agglomerates having an average diameter of 19.5 mm or more and 32 mm or less onto a hearth so as to have a bed density of 0.5 or more and 0.8 or less and heating them. It is described that in this method, the productivity of granular metallic iron can be increased by controlling both the bed density and the average diameter of the agglomerates.

However, when the diameter of the agglomerate is limited to a predetermined range as in the technique described in Patent Document 1, a decrease in yield when producing the agglomerate is unavoidable, resulting in cost I am worried about going up. When the laying density of the agglomerates is in the range of 0.5 or more and 0.8 or less, it is difficult to stack the agglomerates in addition to the close packing, resulting in a low efficiency treatment.

As described above, when nickel oxide ore is mixed and reduced to produce a metal containing nickel and iron, it is important to increase productivity, reduce costs, and improve quality. Despite this, there were many problems.

JP 2011-256414 A

The present invention is a smelting method for producing metal by reducing a mixture containing oxide ore such as nickel oxide ore, which can increase the grade of the obtained metal and efficiently produce high-quality metal. An object of the present invention is to provide a method for smelting oxide ore.

The present inventors have solved the above problems by supplying hydrogen into the reducing furnace and reducing the oxide ore with a carbonaceous reducing agent in a method of performing heat reduction treatment using a burner in a reducing furnace. The present inventors have found that it is possible to complete the present invention.

(1) The first aspect of the present invention includes a mixing step of mixing an oxide ore and a carbonaceous reducing agent to obtain a mixture, charging the obtained mixture into a reducing furnace heated by a burner flame, and a reduction step of subjecting the oxide ore to a reduction treatment with the included carbonaceous reducing agent to obtain a reduced product containing metal and slag, wherein in the reduction step, hydrogen is supplied into the reducing furnace and the carbonaceous reducing agent This is a smelting method for oxide ore in which the oxide ore is subjected to a reduction treatment by

(2) The second aspect of the present invention is the smelting method for oxide ore according to the first aspect, wherein in the reduction step, hydrogen is ejected toward the mixture in the reduction furnace.

(3) A third aspect of the present invention is the method for smelting oxide ore according to the first or second aspect, wherein in the reduction step, hydrogen is ejected toward the flame of a burner.

(4) In the fourth aspect of the present invention, in any one of the first to third aspects, in the reduction step, the hydrogen concentration in the reduction furnace is 0.5% by volume or more and 5.0% by volume or less. It is a method of smelting oxide ore that supplies hydrogen to

(5) A fifth aspect of the present invention is the method for smelting an oxide ore according to any one of the first to fourth aspects, wherein the oxide ore is a nickel oxide ore.

According to the method for smelting oxide ore according to the present invention, high-quality metal can be efficiently produced.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing which shows an example of the flow of the smelting method of a nickel oxide ore. 1 is a diagram (side view) showing one example of the configuration of a reducing furnace that is used for reduction treatment and supplies hydrogen. FIG. FIG. 5 is a diagram (plan view) showing another example of the configuration of a reducing furnace that is used for reduction treatment and supplies hydrogen.

Specific embodiments of the present invention will be described in detail below. In addition, the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention. Further, in this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Outline of smelting method for oxide ore≫
In the method for smelting oxide ore according to the present embodiment, an oxide ore (oxide), which is a raw material ore, is mixed with a carbonaceous reducing agent, and the mixture (pellets) is placed in a smelting furnace (reducing furnace). Metal and slag are generated by performing a reduction treatment.

For example, as the oxide ore, a nickel oxide ore containing nickel oxide, iron oxide, or the like is used as a raw material, and the nickel oxide ore and a carbonaceous reducing agent are mixed to obtain a mixture, and nickel contained in the mixture is preferentially used. reduction and partial reduction of iron to produce ferronickel, which is an alloy of iron and nickel.

In the method for smelting oxide ore according to the present embodiment, a heat reduction treatment method using a burner in a reducing furnace is adopted. At that time, hydrogen is supplied into the reducing furnace and It is characterized by subjecting the oxide ore to a reduction treatment.

According to such a method, the oxidation of the reduced product due to water can be suppressed, and the quality of the obtained metal can be enhanced.

≪2. Smelting method for producing ferronickel using nickel oxide ore>>
In the following, nickel (nickel oxide) and iron (iron oxide) contained in nickel oxide ore, which is the raw material ore, are reduced to produce iron-nickel alloy metals, and then the metals are separated into ferromagnetic A smelting method for producing nickel will be described as an example.

Specifically, as shown in FIG. 1, the nickel oxide ore smelting method according to the present embodiment includes a mixing step S1 in which a nickel oxide ore and a carbonaceous reducing agent are mixed to obtain a mixture; It includes a reduction step S2 in which the mixture is subjected to reduction treatment, and a separation step S3 in which metal and slag are separated from the reduced product.

<2-1. Mixing process>
The mixing step S1 is a step of mixing a nickel oxide ore and a carbonaceous reducing agent as a reducing agent to obtain a mixture. Specifically, in the mixing step S1, first, a carbonaceous reducing agent, which is a first reducing agent, is added to and mixed with a nickel oxide ore, which is a raw material ore. Components, binders, and the like, for example, powders having a particle size of about 0.2 mm or more and 0.8 mm or less are added and mixed to obtain a mixture. The mixing treatment can be performed using a mixer or the like.

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

Examples of the carbonaceous reducing agent include, but are not particularly limited to, coal powder, coke powder, and the like. It is preferable that the carbonaceous reducing agent has the same particle size and particle size distribution as the nickel oxide ore, which is the raw material ore, because it is easily mixed uniformly and the reduction reaction proceeds uniformly.

The content of the carbonaceous reducing agent (the content of the carbonaceous reducing agent contained in the mixture) includes the chemical equivalent required to reduce the total amount of nickel oxide constituting the nickel oxide ore to nickel metal, and iron oxide ( 50.0% by mass when the total value of both chemical equivalents required to reduce ferric oxide) to metallic iron (also referred to as the “total value of chemical equivalents” for convenience) is 100% by mass The following ratio is preferable, and the ratio of 40.0% by mass or less is more preferable. The amount of iron to be reduced can be suppressed, the nickel grade can be improved, and high-quality ferronickel can be produced. The amount of the carbonaceous reducing agent mixed is preferably 10.0% by mass or more, and preferably 15.0% by mass or more, when the total chemical equivalent is 100% by mass. is more preferred. Nickel reduction can be efficiently advanced, and productivity is improved.

As the iron ore, which is an optional component additive, for example, iron ore having an iron grade of about 50.0% by mass or more, hematite obtained by hydrometallurgy of nickel oxide ore, and the like can be used. Examples of flux components include calcium oxide, calcium hydroxide, calcium carbonate, and silicon dioxide. Examples of binders include bentonite, polysaccharides, resins, water glass, and dehydrated cakes.

In the mixing step S1, a mixture is obtained by uniformly mixing raw material powders containing nickel oxide ore. Table 1 below shows an example of the composition (% by mass) of some of the raw material powders mixed in the mixing step S1, but the composition of the raw material powder is not limited to this.

At the time of mixing, kneading may be carried out at the same time in order to improve mixability, or kneading may be carried out after mixing. Kneading can be performed using a batch type kneader such as Brabender, Banbury mixer, Henschel mixer, helical rotor, roll, single-screw kneader, twin-screw kneader, or the like. By kneading the mixture, a shearing force is applied to the mixture, and the agglomeration of the carbonaceous reducing agent, the raw material powder, etc. can be released and uniformly mixed, and the adhesion of each particle can be improved, and the voids can be reduced. can be done. As a result, the reduction reaction can easily occur in the mixture, and the reaction can be performed uniformly, and the reaction time for the reduction reaction can be shortened. In addition, it is possible to suppress variations in quality.

Alternatively, after mixing, or after mixing and kneading, extrusion may be performed using an extruder. As a result, pressure (shearing force) is applied to the mixture, and the aggregation of the carbonaceous reducing agent, the raw material powder, etc. is released, and the mixture can be mixed more uniformly. Additionally, voids within the mixture can be reduced. For these reasons, the reduction reaction of the mixture is more likely to occur uniformly in the reduction step S2, which will be described later, and the quality of the obtained metal can be improved, so that a high-quality metal can be produced.

The extruder is preferably one capable of kneading and molding the mixture under high pressure and high shear force, and examples thereof include a single-screw extruder and a twin-screw extruder. In particular, it is preferable to have a twin-screw extruder. By kneading the mixture under high pressure and high shear, the agglomeration of the mixture of raw material powders can be broken off, the mixture can be kneaded effectively, and the strength of the mixture can be increased. Moreover, by using a machine equipped with a twin-screw extruder, a mixture can be obtained continuously while maintaining high productivity.

Alternatively, the mixture may be molded into a molded product (pellet) having a predetermined shape. The shape of the molding can be, for example, a spherical shape, a rectangular parallelepiped shape, a cubic shape, a cylindrical shape, or the like. Since such a shape is simple and not complicated, it is possible to suppress the occurrence of defective products while suppressing the molding cost, and the quality of the obtained molded product is uniform, suppressing the decrease in yield. can do.

The shape of the molding is particularly preferably spherical. Since the spheroidal molding is used, the reduction treatment can be performed uniformly, and smelting can be performed with little variation and high productivity. When the shape of the molded product is spherical, it can be molded to have a diameter of about 10 mm or more and 30 mm or less. In the case of rectangular parallelepiped, cubic, cylindrical, or the like, the shape can be generally formed so that the inner dimensions in length and width are about 500 mm or less.

The size of the molded product is not particularly limited, but the volume of the molded product is preferably 8000 mm ³ or more. Since the volume of the molded product is 8000 mm ³ or more, the molding cost is suppressed, and the ratio of the surface area to the entire molded product is low, so the reduction treatment is uniformly performed, the variation is small, and the productivity is improved. High smelting is possible.

Also, the obtained mixture may be filled into a predetermined container for reduction. By subjecting the mixture filled in the container to the reduction treatment while the mixture is still filled in the container, the metal reduced in the separation step S3 described later can be easily separated and recovered by a treatment such as magnetic separation, and loss can be reduced. can be suppressed.

In the mixing step S1, the obtained mixture may be subjected to drying treatment. The mixture is mixed with a large amount of water in kneading, molding of moldings, or the like. Although it is not an essential aspect to perform the drying treatment in the present embodiment, by performing the drying treatment on the mixture containing a large amount of water, it is possible to prevent the expansion of the mixture due to the evaporation of water in the reduction treatment described later. .

Furthermore, by subjecting the mixture to a drying treatment, it is possible to suppress contamination of water due to the mixture in the reduction furnace. As a result, the amount of water contained in the atmospheric gas in the reducing furnace can be more effectively reduced, and the oxidation of metals contained in the reduced product can be more effectively suppressed.

The method of drying the mixture is not particularly limited, and includes a method of maintaining the mixture at a predetermined drying temperature (for example, 300° C. or more and 400° C. or less), a method of blowing hot air at a predetermined drying temperature to the mixture, and the like. , conventionally known means can be used. By such drying treatment, for example, the solid content of the mixture is about 70% by mass and the water content is about 30% by mass. The temperature of the mixture itself during this drying treatment is preferably less than 100° C., which can prevent the mixture from bursting due to bumping of moisture or the like.

Moreover, the drying treatment may be continuously performed at once or may be performed in multiple steps. Explosion of the mixture can be more effectively suppressed by performing the drying treatment in multiple steps. In addition, when the drying treatment is performed in a plurality of times, the drying temperature for the second and subsequent times is preferably 150° C. or more and 400° C. or less. By drying in this range, it becomes possible to dry without progressing the reduction reaction.

Table 2 below shows an example of the solid content composition (parts by mass) of the mixture after drying. In addition, the composition of the molding is not limited to this.

<2-2. Reduction process>
The reduction step S2 is a step of charging the obtained mixture into a reduction furnace and subjecting the mixture to a reduction treatment to obtain a reduced product containing metal and slag. By the reduction treatment in the reduction step S2, a smelting reaction (reduction reaction) proceeds based on the carbonaceous reducing agent in the mixture, and in the mixture, ferronickel metal (hereinafter simply referred to as “metal”) and ferronickel Slag (hereinafter simply referred to as "slag") is generated separately.

In the reduction treatment, the nickel oxide ore and iron oxide in the mixture are reduced and metallized in the vicinity of the surface of the mixture where the reduction reaction is likely to proceed, for a short period of time, for example about 1 minute, to form a shell. Form. On the other hand, in the shell, the slag components are gradually melted as the shell is formed to form liquid phase slag. As a result, metal and slag are separated from each other in the mixture.

Then, after about 10 minutes of treatment time, excess carbonaceous reducing agent that does not participate in the reduction reaction is incorporated into the metal, lowering the melting point of the metal and turning the metal into a liquid phase.

The temperature (reduction temperature) in the reduction treatment is not particularly limited, but is preferably in the range of 1200° C. or higher and 1450° C. or lower, and more preferably in the range of 1300° C. or higher and 1400° C. or lower. By performing the reduction within such a temperature range, the reduction reaction can be uniformly induced, and ferronickel with suppressed variations in quality can be produced. Moreover, the desired reduction reaction can be caused in a relatively short period of time by reducing at a reduction temperature in the range of more preferably 1300° C. or higher and 1400° C. or lower.

The time (treatment time) in the reduction treatment is set according to the temperature of the reducing furnace, and is preferably 10 minutes or longer, more preferably 15 minutes or longer.

The amount of heat required for the reduction obtained by multiplying the values of the reduction temperature (°C) and the reduction time (minutes) is preferably in the range of 20000 (°C x minutes) to 40000 (°C x minutes). High quality metal can be efficiently manufactured.

Now, in the reduction step S2, a reduction furnace equipped with a burner is used, and the burner heats the material to a predetermined reduction temperature for reduction treatment. By heating with a burner, reduction treatment can be performed by heating with less energy, making it possible to perform efficient smelting operations. As fuel for the burner, for example, LPG gas (liquefied petroleum gas), LNG gas (natural gas), coal, coke, pulverized coal, or the like can be used. The cost of these fuels is very low, and equipment costs and maintenance costs can be remarkably reduced compared to electric furnaces and the like.

In the conventional method of smelting oxide ore, for example, moisture generated when fuel such as a burner that raises the internal temperature of the reducing furnace is burned may remain in the reducing furnace. If moisture in the atmospheric gas remains in the reducing furnace, the metal contained in the reduced product obtained by the reduction treatment may be oxidized due to the moisture.

This is because an oxidation-reduction reaction proceeds between the metal and water, that is, the metal is oxidized by donating oxygen atoms constituting water molecules to the metal contained in the reduced product.

Therefore, the nickel oxide ore smelting method according to the present embodiment is characterized in that hydrogen is supplied into the reduction furnace when the oxide ore is subjected to a reduction treatment using a carbonaceous reducing agent. By supplying hydrogen, which is a reduced product of water, to the reducing furnace, it is possible to change the chemical equilibrium in the oxidation-reduction reaction between metal and water, thereby suppressing the oxidation reaction of metal.

In addition, when the oxygen supplied to the burner flows into the mixture in the reduction furnace, the reduction reaction of the mixture may be inhibited, and part of the once-produced metal may be oxidized again by the oxygen. Therefore, by supplying hydrogen into the reducing furnace, the hydrogen acts as a deoxidizing agent and reacts with the unreacted oxygen supplied to the burner, so that the oxygen in the reducing furnace can be removed. This makes it possible to further suppress the oxidation reaction of the metal.

In this way, by supplying hydrogen into the reducing furnace when the oxide ore is reduced by the carbonaceous reducing agent, the oxidation reaction of the produced metal is suppressed, and oxygen in the reducing furnace is removed. It is possible to further suppress the oxidation reaction of the metal, thereby efficiently producing a high-quality metal.

In this reduction step, the oxide ore is subjected to a reduction treatment by the carbonaceous reducing agent contained in the mixture, and the mode of performing the reduction treatment with hydrogen itself, such as the reduction treatment using a so-called hydrogen reduction furnace, is clearly different. .

It is preferable to supply hydrogen into the reducing furnace so that the hydrogen concentration in the reducing furnace is 0.5% by volume or more in 100% by volume of the atmospheric gas in the reducing furnace. Oxidation of the metal contained in the reduced product can be more effectively suppressed by setting the concentration to 0.5% by volume or more in 100% by volume of the atmospheric gas in the reducing furnace. It is preferable to supply hydrogen into the reducing furnace so that the hydrogen concentration in the reducing furnace is 5.0% by volume or less in 100% by volume of the atmospheric gas in the reducing furnace. Excessive reduction of the mixture can be suppressed and a high-quality metal can be produced by setting the amount to 5.0% by volume or less in 100% by volume of the atmospheric gas in the reducing furnace.

In addition, the mode of supplying hydrogen into the reducing furnace is not particularly limited as long as it can be supplied into any space in the reducing furnace, but hydrogen is jetted toward the mixture in the reducing furnace. is preferred. As a result, it is possible to increase the concentration of hydrogen in the atmospheric gas that comes into direct contact with the mixture, so that it is possible to more effectively prevent part of the generated metal from being oxidized.

FIG. 2 is a diagram (side view) for explaining a specific mode example of supplying hydrogen into the reducing furnace (an example of ejecting hydrogen toward the mixture from a pipe arranged above the mixture P). . As shown in FIG. 2, in the reducing furnace 1, a pipe 12 is provided above the mixture P, and hydrogen H is jetted toward the mixture P from holes provided in the pipe 12. there is In such a reduction furnace 1, reduction treatment is performed in a state in which the hydrogen concentration in the atmospheric gas directly contacting the mixture P is increased. This makes it possible to more effectively prevent part of the generated metal from being oxidized.

Further, FIG. 3 is a diagram (plan view) for explaining another embodiment of supplying hydrogen into the reducing furnace (an example in which hydrogen is jetted toward the mixture from a pipe arranged on the furnace wall of the reducing furnace). is. As shown in FIG. 3 , the reducing furnace 2 is provided with a pipe 22 on a furnace wall 23 of the reducing furnace 2 , and hydrogen H is jetted out from the pipe 22 toward the mixture P. In such a reducing furnace 2 as well, the reduction treatment is performed in a state where the hydrogen concentration in the atmospheric gas directly contacting the mixture P is increased. This makes it possible to more effectively prevent part of the generated metal from being oxidized.

2 and 3, an example in which hydrogen is jetted toward the mixture in the reducing furnace has been described. It is not limited to what is ejected. As for the mode of supplying hydrogen into the reducing furnace, it is also preferable to jet hydrogen toward the flame of the burner. Oxygen in the reducing furnace can be more effectively removed, and the inflow of oxygen into the mixture in the reducing furnace can be more appropriately suppressed. This makes it possible to more effectively prevent part of the generated metal from being oxidized.

Specifically, the oxygen concentration in the reduction furnace after the reduction treatment is preferably 0.5% by volume or less in 100% by volume of the atmospheric gas in the reduction furnace. Moreover, it is more preferable to carry out the reduction treatment so that the oxygen concentration in the reduction furnace is 0.3% by volume or less. Here, since the oxygen concentration in the reducing furnace after the reduction treatment depends on the amount of hydrogen supplied to the reducing furnace, it is adjusted by the amount of air supplied to the burner and the amount of hydrogen supplied to the reducing furnace. be able to.

Moreover, from the viewpoint of further suppressing the reduction reaction of water, the water contained in the atmosphere gas generated by the reduction treatment may be discharged from the reduction furnace to the outside. When the unreacted oxygen supplied to the burner reacts with hydrogen, water is produced, but by discharging the moisture contained in the atmospheric gas from the reduction furnace to the outside, part of the produced metal is oxidized. It can be prevented more effectively. The method of discharging water from the reduction furnace is not particularly limited, and for example, a method of discharging water by liquefying the water contained in the atmosphere gas generated by the reduction process can be used.

<2-3. Separation process>
The separation step S3 is a step of separating metal and slag from the reduced product obtained in the reduction step S2. Specifically, the metal phase is separated and recovered from the mixture (mixture) containing the metal phase and the slag phase obtained by the reduction heat treatment of the mixture filled in the container.

Methods for separating the metal phase and the slag phase from the mixture of the metal phase and the slag phase obtained as a solid include, for example, in addition to removing unnecessary substances by sieving, separation by specific gravity, separation by magnetic force, etc. method can be used.

In addition, the obtained metal phase and slag phase can be easily separated from each other due to their poor wettability. Alternatively, the metal phase and the slag phase can be easily separated from the mixture by applying an impact such as giving a predetermined vibration during sieving.

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

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

<Example 1, Comparative Example 1>
Nickel oxide ore as a raw material ore, iron ore, silica sand and limestone as flux components, a binder, and a carbonaceous reducing agent (coal powder, carbon content: 82% by mass, average particle size: about 75 μm) are mixed in appropriate amounts. of water was added and mixed using a mixer to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would be a proportion of 28.5% by mass. The resulting mixture was then evenly divided into 18 samples.

Next, with a pan-type granulator, 18 mixtures (samples) having a diameter of 14.5 ± 1.0 mm, which were formed into spheres by adding water as appropriate to the mixture obtained (Examples 2-1 to 2- 14, Comparative Examples 2-1 to 2-4) were obtained. Before reduction, each sample was dried by blowing hot air at 170° C. to 250° C. so that the solid content was about 70% by mass and the water content was about 30% by mass.

Next, the mixtures (samples) of Examples 1-1 to 1-14 and Comparative Examples 1-1 to 1-4 were charged into a reducing furnace, and hydrogen was supplied through piping in the reducing furnace. "Hydrogen concentration (% by volume)" in Table 3 means the hydrogen concentration near the center of the reduction furnace.

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _SiO2 , _and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such a reduction treatment, the samples of Examples 1-1 to 1-14 and Comparative Examples 1-1 to 1-4 after the cooling of the resulting reduced material were pulverized, and then the metal was recovered by magnetic separation.

For each sample after the reduction heat treatment, the nickel metallization rate, the nickel content rate in the metal, and the metal recovery rate were analyzed and calculated using an ICP emission spectrometer (SHIMAZU S-8100 type).

The nickel metallization rate, nickel content rate in metal, and nickel metal recovery rate were calculated by the following equations (1), (2), and (3).
Nickel metallization rate = mass of nickel in metal/(mass of all nickel in reduced product) x 100 (%) (1) formula Nickel content in metal = mass of nickel in metal/(metal Total mass of nickel and iron in the inside) × 100 (%) (2) formula Nickel metal recovery rate = amount of nickel recovered / (amount of ore charged × content of nickel in ore) × 100・・(3) formula

Table 3 below shows the oxygen concentration in the reducing furnace after the heat reduction treatment, the nickel metallization rate, the nickel content in the metal, and the nickel metal recovery rate for each sample.

As can be seen from the results in Table 3, in Examples 1-1 to 1-14 in which hydrogen was supplied into the reducing furnace, the nickel metallization rate and the nickel content in the metal were higher than those in Comparative Examples 1-1 to 1-4. and the metal recovery rate were both high. It is considered that this is because the oxidation of the reduced product could be suppressed by supplying hydrogen into the reducing furnace to carry out the reduction treatment.

<Example 2, Comparative Example 2>
As in Example 1 and Comparative Example 1, nickel oxide ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder, carbon content: 85% by mass, average particle diameter: about 75 μm) were mixed using a mixer while adding an appropriate amount of water to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would give a ratio of 28.0% by mass. The resulting mixture was then evenly divided into 18 samples.

Next, by appropriately adding water to the obtained mixture and using a pan-type granulator, 18 mixtures (samples) having a diameter of 16.0 ± 1.0 mm formed into spheres (Example 2-1 2-14, Comparative Examples 2-1 to 2-4) were obtained. Before reduction, each sample was dried by blowing hot air at 170° C. to 250° C. so that the solid content was about 70% by mass and the water content was about 30% by mass.

Next, the mixtures (samples) of Examples 2-1 to 2-14 and Comparative Examples 2-1 to 2-4 were charged into a reducing furnace, and hydrogen was supplied from piping in the reducing furnace as shown in FIG. supplied. At this time, hydrogen was jetted toward the mixture from a pipe provided above the mixture P in the reduction furnace. "Hydrogen concentration (% by volume)" in Table 4 means the hydrogen concentration near the center of the reduction furnace.

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _SiO2 , _and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such a reduction treatment, the samples of Examples 2-1 to 2-14 and Comparative Examples 2-1 to 2-4 after cooling of the resulting reduced material were pulverized, and then the metal was recovered by magnetic separation.

Table 4 below shows the oxygen concentration in the reducing furnace after the heat reduction treatment, the nickel metallization rate, the nickel content in the metal, and the nickel metal recovery rate for each sample.

As can be seen from the results in Table 4, in Examples 2-1 to 2-14 in which hydrogen was supplied into the reducing furnace, the nickel metallization rate and the nickel content in the metal were higher than those in Comparative Examples 2-1 to 2-4. and the metal recovery rate were both high. It is considered that this is because the oxidation of the reduced product could be suppressed by supplying hydrogen into the reducing furnace to carry out the reduction treatment.

Furthermore, in Examples 2-1 to 2-14, hydrogen was jetted toward the mixture from the pipe provided above the mixture P in the reduction furnace, so the hydrogen concentration in the atmospheric gas that directly contacted the mixture was increased. It is considered that this is because the reduction treatment could be performed in a state in which a portion of the generated metal was more effectively prevented from being oxidized.

<Example 3, Comparative Example 3>
As in Example 1 and Comparative Example 1 above, nickel oxide ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder, carbon content: 82% by mass, average particle size diameter: about 75 μm) were mixed using a mixer while adding an appropriate amount of water to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would be 29.0% by mass. The resulting mixture was then evenly divided into 18 samples.

Next, 18 spherically shaped mixtures (samples) with a diameter of 15.0 ± 1.0 mm were prepared by adding water as appropriate to the resulting mixture and using a pan-type granulator (Example 3- 1 to 3-14 and Comparative Examples 3-1 to 3-4). Before reduction, each sample was dried by blowing hot air at 170° C. to 250° C. so that the solid content was about 70% by weight and the water content was about 30% by weight.

Next, the mixtures (samples) of Examples 3-1 to 3-14 and Comparative Examples 3-1 to 3-4 were charged into a reducing furnace, and as shown in FIG. Hydrogen was supplied from the pipe. At this time, hydrogen was jetted toward the mixture from a pipe provided on the furnace wall of the reduction furnace. "Hydrogen concentration (% by volume)" in Table 5 means the hydrogen concentration near the center of the reduction furnace.

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _SiO2 , _and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such reduction treatment, the obtained reduced material cooled sample was pulverized, and then the metal was recovered by magnetic separation.

Table 5 below shows the oxygen concentration in the reducing furnace after the heat reduction treatment, the nickel metallization rate, the nickel content rate in the metal, and the nickel metal recovery rate for each sample.

As can be seen from the results in Table 5, in Examples 3-1 to 3-14, in which hydrogen was supplied into the reduction furnace by blowing hydrogen toward the mixture from a pipe provided on the furnace wall of the reduction furnace, comparison Compared with Examples 3-1 to 3-4, the nickel metallization ratio, the nickel content in the metal, and the metal recovery ratio all increased. It is considered that this is because the oxidation of the reduced product could be suppressed by supplying hydrogen into the reducing furnace to carry out the reduction treatment.

Furthermore, in Examples 3-1 to 3-14, hydrogen was jetted toward the mixture from the pipe provided on the furnace wall of the reduction furnace, so that the hydrogen concentration in the atmosphere gas in direct contact with the mixture was increased. It is believed that this is because the fact that the reduction treatment could be applied made it possible to more effectively prevent a part of the generated metal from being oxidized.

<Example 4, Comparative Example 4>
As in Example 1 and Comparative Example 1 above, nickel oxide ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder, carbon content: 82% by mass, average particle size diameter: about 75 μm) were mixed using a mixer while adding an appropriate amount of water to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would give a ratio of 28.0% by mass.

Next, 18 spherically shaped mixtures (samples) with a diameter of 14.0 ± 1.0 mm were prepared by adding water as appropriate to the resulting mixture and using a pan-type granulator (Example 4- 1 to 4-14 and Comparative Examples 4-1 to 4-4). Before reduction, each sample was dried by blowing hot air at 170° C. to 250° C. so that the solid content was about 70% by weight and the water content was about 30% by weight.

Next, the mixtures (samples) of Examples 4-1 to 4-14 and Comparative Examples 4-1 to 4-4 were charged into a reducing furnace, and from a pipe provided above the burner in the reducing furnace. Hydrogen was supplied. At this time, hydrogen was jetted from the piping toward the mixture toward the flame of the burner. "Hydrogen concentration (% by volume)" in Table 6 means the hydrogen concentration near the center of the reduction furnace.

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _SiO2 , _and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such reduction treatment, the obtained reduced material cooled sample was pulverized, and then the metal was recovered by magnetic separation.

Table 6 below shows the oxygen concentration in the reducing furnace after the heat reduction treatment, the nickel metallization rate, the nickel content in the metal, and the nickel metal recovery rate for each sample.

As can be seen from the results in Table 6, in Examples 4-1 to 4-14 in which hydrogen was supplied into the reduction furnace by blowing hydrogen toward the mixture from a pipe provided on the furnace wall of the reduction furnace, comparison Compared with Examples 4-1 to 4-4, the nickel metallization ratio, the nickel content in the metal, and the metal recovery ratio all increased. It is considered that this is because the oxidation of the reduced product could be suppressed by supplying hydrogen into the reducing furnace to carry out the reduction treatment.

Furthermore, in Examples 4-1 to 4-14, hydrogen was jetted toward the flame of the burner from a pipe provided above the burner in the reducing furnace, so the flow of oxygen into the mixture in the reducing furnace was suppressed. It is believed that this is because it has become possible to more effectively prevent oxidation of a part of the generated metal by appropriately suppressing it.

Reference Signs List 1, 2 reducing furnace 1r, 2r furnace space 11, 21 hearth 12, 22 piping 13, 23 furnace wall P mixture H hydrogen

Claims (3)

A nickel oxide ore smelting method for producing ferronickel by reducing nickel oxide and iron oxide contained in the nickel oxide ore,
a mixing step of mixing nickel oxide ore and a carbonaceous reducing agent to obtain a mixture;
The resulting mixture is charged into a reduction furnace equipped with a burner, and the mixture is heated by the burner, so that the nickel oxide ore is reduced by the carbonaceous reducing agent contained in the mixture to produce metal and slag. a reduction step of obtaining a reduced product containing
In the reduction step, hydrogen is supplied into the reduction furnace equipped with a burner so that the hydrogen concentration is 0.5% by volume or more and 5.0% by volume or less, thereby reducing the oxygen concentration in the reduction furnace to 100% of the atmosphere gas. A method for smelting a nickel oxide ore, wherein the nickel oxide ore is subjected to a reduction treatment at a temperature of 1300° C. or higher and 1400° C. or lower with the carbonaceous reducing agent so as to achieve a state of 0.5% by volume or less in vol%. The method for smelting nickel oxide ore according to claim 1, wherein in the reduction step, hydrogen is jetted toward the mixture in the reduction furnace. The method for smelting nickel oxide ore according to claim 1, wherein in the reduction step, hydrogen is jetted toward a flame of a burner.

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