JP2021167461A - Method for smelting oxide ore - Google Patents

Abstract

To provide a method for smelting an oxide ore which can efficiently manufacture metal having high quality.SOLUTION: A method for smelting an oxide ore includes: a mixing step S1 of obtaining a mixture M containing an oxide ore and a carbonaceous reducer; and a reduction step S3 of subjecting the mixture M to reduction treatment in a reduction furnace 10 having a movable burner (burner)14, in which the reduction step S3 subjects the mixture M to the reduction treatment while changing a flame ejection position and/or a flame ejection direction ejected from the movable burner (burner) 14. The reduction step S3 preferably obtains a melt by subjecting the mixture M to the reduction treatment.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pyrometallurgy method for oxide ore, and more specifically, smelting to produce a metal as a reduced product by reducing an oxide ore such as nickel oxide ore as a raw material with a carbonaceous reducing agent. Regarding the method.

As a method for smelting nickel oxide ore called limonite or saprolite, which is a type of oxide ore, a pyrometallurgical method for producing nickel matte using a smelting furnace, iron and nickel using a rotary kiln or a mobile hearth furnace. Pyrometallurgical smelting method for producing ferronickel, which is an alloy of ing.

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

Specifically, when the nickel oxide ore is agglomerated, that is, when the powdery or finely granular ore is agglomerated, the nickel oxide ore is mixed with other components, for example, a reducing agent such as a binder or coke. After the water content is adjusted, the mixture is charged into a lump manufacturing machine, and for example, a lump (pellet, briquette, etc.) having a side or a diameter of about 10 mm to 30 mm is simply referred to as "pellet". ) Is common.

The pellets obtained in the form of agglomerates need to have a certain degree of air permeability in order to "fly" the contained moisture. Further, if the reduction does not proceed uniformly in the pellets in the subsequent reduction treatment, the composition of the obtained reduced product becomes non-uniform, causing inconveniences such as metal being dispersed or unevenly distributed. Therefore, it is important to mix the mixture uniformly when producing the pellets and to maintain the temperature as uniform as possible when reducing the obtained pellets.

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 it from the slag produced at the same time, and the recovery rate (yield) as ferronickel is greatly reduced. It ends up. Therefore, a treatment for coarsening the reduced ferronickel is required.

For example, Patent Document 1 describes that in producing a granular metal by heating an agglomerate containing a metal oxide and a carbonaceous reducing agent and reducing and melting the metal oxide contained in the agglomerate. A technology aimed at proposing a technology that further enhances productivity is disclosed.

Specifically, a mass containing a metal oxide and a carbonaceous reducing agent is supplied onto the hearth of a mobile bed type reduction melting furnace and heated to reduce and melt the metal oxide, and then the obtained granular metal is obtained. This is a method for producing a granular metal that is cooled and then discharged to the outside of the furnace to be recovered. When the temperature inside the furnace in the latter half region of the furnace where the reduced iron in the agglomerates is carburized, melted, and agglomerated is set to 1400 to 1550 ° C., and the distance between the agglomerates spread on the furnace bed is set to 0. When the relative value of the projected area ratio of the agglomerates spread on the hearth to the maximum projected area ratio of the agglomerates on the hearth is taken as the spread density, the agglomerates spread on the hearth. A method for producing a granular metal, which comprises supplying an agglomerate having an average diameter of 19.5 mm or more and 32 mm or less onto a hearth when heating with a density of 0.5 or more and 0.8 or less is disclosed. ..

Further, Patent Document 1 also shows that the productivity of granular metallic iron can be improved by controlling the lump density and the average diameter of the agglomerates together.

However, although the technique described in Patent Document 1 is only a technique relating to the reaction on the outer surface side of the agglomerate, it goes without saying that the most important factor for the reduction reaction is the state in the agglomerate where the reduction reaction occurs. stomach. That is, it is considered that the reaction efficiency and uniform reduction reaction can be realized by controlling the reduction reaction inside the agglomerate, and as a result, high quality metal can be produced.

Further, as in the technique described in Patent Document 1, if the diameter of the agglomerate is limited to a predetermined range, a decrease in the yield when producing the agglomerate is unavoidable, and as a result, the cost is reduced. There is a concern that it will be up. In addition, when the spread density of the agglomerates is in the range of 0.5 to 0.8, it is not finely packed and it is difficult to stack the agglomerates, so that the treatment is inefficient.

As mentioned above, in producing metal containing nickel and iron by mixing and reducing nickel oxide ore, it is important to increase productivity, reduce cost, and improve quality. Nevertheless, there were many problems.

Japanese Unexamined Patent Publication No. 2011-256414

The present invention has been proposed in view of such circumstances, and an object of the present invention is to provide a method for smelting an oxide ore capable of efficiently producing high-quality metal.

As a result of diligent studies, the present inventor has found that the above-mentioned problems can be solved by subjecting the mixture to a reduction treatment while changing the ejection position of the flame ejected from the burner using a reduction furnace equipped with a burner. We have found and completed the present invention.

(1) The first aspect of the present invention includes a mixing step of obtaining a mixture containing an oxide ore and a carbonaceous reducing agent, and a reduction step of reducing the mixture in a reduction furnace equipped with a burner. The reduction step is a method for smelting oxide ore in which the mixture is reduced while changing the ejection position of the flame ejected from the burner.

(2) The second aspect of the present invention includes a mixing step of obtaining a mixture containing an oxide ore and a carbonaceous reducing agent, and a reduction step of reducing the mixture in a reduction furnace equipped with a burner. The reduction step is a method for smelting oxide ore in which the mixture is reduced while changing the ejection direction of the flame ejected from the burner.

(3) The third aspect of the present invention is the smelting method according to the first or second invention, in which the reduction step is a smelting method in which the mixture is subjected to a reduction treatment to obtain a melt.

(4) The fourth aspect of the present invention is that in any one of the first to third inventions, the oxide ore is a nickel oxide ore, and the mixture containing the nickel oxide ore is subjected to a reduction treatment to obtain ferronickel. This is a method for smelting oxidized ore to be produced.

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

It is a process drawing which shows an example of the flow of the smelting method of nickel oxide ore. It is a schematic diagram which shows an example of the structure of the reduction furnace, and is the figure for demonstrating the state of the reduction process in the reduction furnace.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention. Further, in the present specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Outline of the present invention ≫
According to the present invention, for example, an oxide ore such as nickel oxide ore is used as a raw material, and the oxide obtained by mixing the oxide ore and a carbonaceous reducing agent is reduced to produce an oxide ore for producing a metal as a reduced product. It is a smelting method. For example, when nickel oxide ore is used as a raw material ore, ferronickel metal, which is an alloy of nickel of iron, is produced as a reduced product.

Specifically, in the method for smelting oxide ore according to the present invention, a mixture of oxide ore and a carbonaceous reducing agent is charged into a reduction furnace having a burner (burner furnace), and a flame ejected from the burner is used. It is characterized in that the mixture is subjected to a reduction treatment while changing the ejection direction and / or the ejection position.

According to such a method, the quality of the obtained metal can be improved by subjecting the mixture to the reduction treatment while changing the ejection direction and / or the ejection position of the flame.

≪2. Nickel oxide ore smelting method ≫
In the following, as a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”), nickel oxide ore is used as a raw material ore, and nickel (nickel oxide) and iron (iron oxide) contained in the nickel oxide ore are used. ) And are subjected to a reduction treatment to produce a melt of an iron-nickel alloy (ferronickel), and a smelting method for producing ferronickel by separating the metal from the melt is described as an example. do.

In the present invention, it is not an essential aspect to subject the mixture to a reduction treatment to obtain a melt, but by changing the ejection direction and / or ejection position of the flame, the entire mixture is uniformly heated to obtain the mixture. Since it is possible to effectively reduce the mixture in a short treatment time by obtaining the melt of the above, high quality ferronickel can be produced at a lower cost and with higher productivity.

≪2-1. Method for smelting nickel oxide ore of the first embodiment ≫
FIG. 1 is a process diagram showing an example of a flow of a nickel oxide ore smelting method according to the present embodiment. As shown in FIG. 1, the smelting method of the nickel oxide ore includes a mixing step S1 of mixing the nickel oxide ore and a carbonaceous reducing agent to obtain a mixture, a drying step S2 of drying the obtained mixture, and a burner. It has a reduction step S3 in which a reduction treatment is performed on the mixture after drying in a reduction furnace provided with the above, and a recovery step S4 in which the obtained metal and slag are separated and the metal is recovered.

[Mixing process]
The mixing step S1 is a step of mixing the raw material powder containing nickel oxide ore to obtain a mixture. Specifically, in the mixing step S1, nickel oxide ore, which is a raw material ore, and a carbonaceous reducing agent are mixed, and as an additive of an optional component, iron ore, a flux component, a binder, etc., for example, have a particle size of 0. . Mix powders of about 1 mm to 0.8 mm to obtain a mixture.

At the time of mixing, a predetermined amount of water can be added. By adding water and mixing, the mixability of the raw material powder can be improved. The mixing process can be performed using a known mixer or the like.

In the mixing step S1, each raw material powder may be mixed and kneaded in order to improve the mixing property. By kneading, a shearing force is applied to the mixture obtained by mixing the raw material powders, and the agglomeration of the raw material ore, the carbon reducing agent, etc. can be released, and the mixture can be mixed more uniformly and the voids between the particles can be formed. It can be reduced and a uniform reaction can be produced when subjected to the reduction treatment. The kneading can be performed using a twin-screw kneader or the like.

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

When using nickel oxide ore, it may be classified or pulverized to a predetermined size. By classifying, crushing, etc., the particle size can be made uniform within a certain range, and by eliminating large-sized ores by crushing, etc., the miscibility with carbonaceous reducing agents, etc. can be improved, and in the reduction treatment. Uniformity can be improved.

The carbonaceous reducing agent is not particularly limited, and examples thereof include coal powder and coke powder. The carbonaceous reducing agent preferably has a particle size equivalent to that of the nickel oxide ore, which is the raw material ore described above. As a result, the mixing property with the nickel oxide ore can be improved, and the uniformity during the reduction treatment can be improved.

The mixing amount of the carbonaceous reducing agent is 80% by mass or less when the amount of the carbonaceous reducing agent required to reduce the nickel oxide and iron oxide constituting the nickel oxide ore in just proportion is 100% by mass. The ratio is preferably 60% by mass or less, more preferably 60% by mass or less. By setting the mixing amount of the carbonaceous reducing agent to 80% by mass or less with respect to the total value of 100% by mass of chemical equivalents in this way, the reduction reaction can be efficiently promoted. The lower limit of the mixing amount of the carbonaceous reducing agent is not particularly limited, but is preferably 15% by mass or more, preferably 20% by mass or more, based on 100% by mass of the total chemical equivalent. It is more preferable to do so.

The amount of carbonaceous reducing agent required to reduce nickel oxide and iron oxide in just proportion is the chemical equivalent required to reduce the total amount of nickel oxide to nickel metal, and iron oxide is iron metal. It can be rephrased as the total value with the chemical equivalent required for reduction to (hereinafter, also referred to as "total value of chemical equivalent").

The iron ore as an additive of an optional component is not particularly limited, and for example, iron ore having an iron grade of about 50% by mass or more, hematite obtained by hydrometallurgy of nickel oxide ore, or the like can be used.

Examples of the binder include bentonite, polysaccharides, resins, water glasses, dehydrated cakes and the like. Moreover, as a flux component, for example, calcium oxide, calcium hydroxide, calcium carbonate, silicon dioxide and the like can be mentioned.

Table 1 below shows an example of the composition (% by weight) of some of the raw material powders to be mixed in the mixing step S1. The composition of the raw material powder is not limited to this.

[Drying process]
The drying step S2 is a step of drying the obtained mixture. In the present embodiment, it is not essential to provide the drying step S2, but by drying the mixture prior to the reduction treatment, the reduction treatment can be uniformly applied to the mixture and the mixture is surely ensured. It can be reduced by heating above the melting temperature.

When the treatment is performed in the drying step S2 in this way, the dried mixture is charged into the reduction furnace and then subjected to the treatment in the reduction step S3.

The drying temperature is not particularly limited, but is preferably in the range of 150 ° C. or higher and 400 ° C. or lower. By performing the drying treatment in such a range, the mixture can be efficiently dried while suppressing the reaction of the mixture from proceeding in the treatment. Further, even when the mixture is molded into a predetermined shape and subjected to the reduction treatment, by drying in the above temperature range, it is possible to prevent the molded product from being rapidly heated by the reduction treatment and bursting. Can be done.

The drying method is not particularly limited. For example, a method of charging the mixture into a drying facility whose inside is adjusted to a predetermined drying temperature and holding the mixture for a predetermined time to dry the mixture, a method of blowing hot air having a predetermined drying temperature onto the mixture to dry the mixture, and the like. Can be mentioned.

Alternatively, the exhaust gas generated in the reduction furnace that performs heat reduction may be used for drying. Since the exhaust gas generated through the reduction treatment has a very high temperature, it is suitable for drying a mixture containing nickel oxide ore. Further, since the temperature is high, the drying treatment can be performed while suppressing the gas flow rate, and thereby the dust generation rate in the drying treatment can be suppressed. When the exhaust gas from the reduction furnace is used, it is preferable to connect the reduction furnace and the drying equipment with a pipe and directly transfer the exhaust gas generated from the reduction furnace to the drying equipment.

Table 2 below 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.

In addition, the drying treatment may be performed at the same time as the mixing in the above-mentioned mixing step S1, and in the case where the drying is also performed in such a mixing step S1 or when the ore that does not need to be dried is used as a raw material, the drying step S2 Can be omitted. Further, for example, when an ore having a strong adhesiveness is used as a raw material, it may be mixed after being dried, and the process may be appropriately selected according to the properties of the ore, the carbonaceous reducing agent and the like.

[Reduction process]
The reduction step S3 is a step of charging the mixture into a reduction furnace and reducing the mixture to produce metal and slag. Specifically, in the method for smelting nickel oxide ore according to the present embodiment, a reduction furnace equipped with a burner (hereinafter, also referred to as “burner furnace”) is used, and the oxide ore is reduced by heating the mixture with a burner. do.

Here, in the reduction treatment using the burner furnace in the reduction step S3, the reduction reaction of the nickel oxide ore gradually proceeds with the heating of the mixture charged in the furnace by the burner, so that the mixture is not in a molten state. The reduction reaction also occurs in the solid state of. In the burner furnace, as the reduction reaction to the nickel oxide ore progressed, the mixture gradually changed from the solid state to the liquid state by the burner heating, that is, the molten state, and finally produced by the heat reduction treatment by the burner. A molten metal and slag can be obtained.

In heating using a burner, processing can be performed at a significantly lower cost than heating using electricity or the like, and economic efficiency can be improved. Specifically, in the burner furnace, for example, LPG gas, LNG gas, coal, coke, pulverized coal, etc. are used as fuel, but the cost of these fuels is very low, and the equipment cost and maintenance cost are also high. It can be suppressed at a much lower cost than an electric furnace or the like.

Further, in the burner furnace, maintenance is very easy, continuous operation can be effectively performed, and operation efficiency can be improved as compared with a kiln or the like. For example, in the case of an operation using a kiln, the ore adheres to the furnace in a semi-melted state and grows, so the operation is stopped about once every two weeks to remove the deposits, etc. Will need to be done. On the other hand, in the burner furnace, the charged ore can be reduced in a short time and the entire amount can be discharged as metal and slag, so that the semi-melt can be suppressed from adhering to the inside of the furnace. In addition, since the structure is simpler and the number of attached equipment is smaller than that of the electric furnace of the Elchem method, it is possible to reduce the operation cost and the cost of regular maintenance.

By the way, in the conventional method of reducing nickel oxide ore, since the entire mixture cannot be heated uniformly, it takes a long time for the metal grains to grow, and the quality of the obtained metal cannot be improved. There was a problem that the cost was high because it took time.

Further, if the entire mixture cannot be heated uniformly, the mixture is partially in a semi-melted state, which may cause the semi-melt to adhere to the reduction furnace. If this semi-melt grows in the reduction furnace, the operation for maintenance must be stopped, and there is a problem that the operation efficiency is significantly lowered.

Therefore, the nickel oxide ore smelting method according to the present embodiment is characterized in that the mixture is subjected to a reduction treatment while changing the ejection position of the flame ejected from the burner. As a result, it is possible to effectively reduce the nickel in a short processing time, and nickel can be reduced at a rate of approximately 100% by controlling the atmosphere in the furnace, which enables sufficient operation. In addition, since it can be reduced by a short-time treatment, composition variation due to oxidation of the produced metal is less likely to occur.

Furthermore, by reducing the mixture while changing the position of the flame ejected from the burner, it is possible to more effectively prevent the semi-melt from adhering to the inside of the furnace, which makes maintenance easier and reduces troubles. The cost can be reduced accordingly. Furthermore, the operation is stabilized because the mixture can be melted uniformly. As a result, high-quality ferronickel can be produced inexpensively and with high productivity.

FIG. 2 is a diagram (cross-sectional view) schematically showing a configuration example of a reduction furnace having a burner. As shown in FIG. 2, in the reduction furnace 10, the processing unit 11 that heats the mixture M to perform the reduction treatment, the charging inlet 12 that charges the mixture M into the processing unit 11, and the metal M1 obtained by the reduction treatment. It is provided with a discharge port 13 for discharging the above.

Then, in the processing section 11 of the reduction furnace 10, a movable burner 14 is provided above the movable burner 14, and the flame ejection direction of the movable burner 14 is fixed in the vertical downward direction and in the vertical direction (vertical direction). It is movable. Then, in the processing unit 11, a reduction reaction is caused by heating by the movable burner 14, and the mixture is brought into a molten state as the reduction reaction progresses. At this time, by moving the movable burner 14 in the vertical direction (vertical direction), the position where the flame is ejected is changed and the mixture is reduced. By applying the reduction treatment to the mixture while changing the ejection position of the flame ejected from the burner in the vertical direction (vertical direction) in this way, it is possible to uniformly heat the inside of the reduction furnace, which is a short-time treatment. You will be able to effectively reduce it in time. As a result, high-quality ferronickel can be produced inexpensively and with high productivity. The vertical direction (vertical direction) may be substantially the vertical direction (substantially vertical direction).

In particular, by reducing the mixture while changing the flame ejection position in the vertical direction (vertical direction), not only the lower mixture M in the reduction furnace but also the upper part in the reduction furnace is effectively heated and reduced. It is possible to more effectively suppress the growth of the semi-melt adhering to the upper part of the furnace.

A movable burner that can move the flame ejection position in the vertical direction (vertical direction) fixes the burner to a rail extending in the vertical direction (vertical direction), and the burner fixed to the rail is moved up and down manually or electrically. It may be movable in the direction (vertical direction), or the shaft itself provided with the flame ejection port may be extendable manually or electrically.

The method for smelting oxide ore is not limited to changing the position of the flame ejected by moving the movable burner in the vertical direction (vertical direction). For example, the flame ejected direction is fixed in the vertical downward direction. The movable burner may be moved in the horizontal direction in a translational manner to change the position of the flame ejected. By making it possible to heat the entire mixture more uniformly, it becomes possible to effectively reduce the mixture in a short treatment time. The flame ejection position may be changed in the vertical direction (vertical direction) and in the horizontal direction. Further, the horizontal direction may be a substantially horizontal direction.

A movable burner that can move the flame ejection position in the horizontal direction is, for example, one in which the burner is fixed to a horizontally extending rail and the burner fixed to the rail can be moved horizontally by manual or electric operation. It should be.

By heating with the movable burner 14, the mixture becomes a molten state as the reduction reaction progresses, and finally the molten metal M1 and the slag M2 are formed. Further, when the molten metal (molten metal) M1 is deposited under the slag M2 due to the difference in specific gravity, even if the oxygen partial pressure and the CO partial pressure fluctuate in the furnace atmosphere, the metal under the slag M2 is under the slag M2. The influence of the metal M1 accumulated on the bottom of the furnace on the composition can be suppressed.

The molten metal separated by the difference in specific gravity is discharged from the discharge port 13. The discharge port 13 is provided at a position where the metal M1 (metal layer) constituting the lower layer of the reduced product exists, and the metal M1 separated by the difference in specific gravity can be selectively discharged and recovered. A slag discharge port may be provided above the discharge port 13.

Further, in heating using a burner, it is preferable to control the air-fuel ratio of the burner within a predetermined range. Oxidation of metal M1 accumulated in the bottom of the furnace under the slag is relatively difficult to proceed, but by controlling the air-fuel ratio of the burner within a predetermined range, the oxygen concentration in the atmosphere inside the furnace is reduced, and the metal is further reduced. Oxidation of M1 can be suppressed, and high-quality fernick can be stably produced.

Specifically, the air-fuel ratio of the burner is controlled to be preferably in the range of 0.8 or more and 1.1 or less, more preferably in the range of 0.85 or more and 0.95 or less to heat the mixture. The air-fuel ratio refers to the mass ratio of air to fuel.

Here, in the reduction treatment using a burner, it is preferable to heat the obtained metal M1 and the slag M2 so that the respective temperatures are in the range of 1300 ° C. or higher and 1700 ° C. or lower. In particular, it is preferable to heat the obtained metal M1 so that the temperature is in the range of 1400 ° C. or higher and 1600 ° C. or lower, and the temperature of the slag M2 is in the range of 1480 ° C. or higher and 1680 ° C. or lower. By heating the metal M1 and the slag M2 so that the temperatures are in such a range, the reduction reaction can be effectively promoted, and a high-quality metal M1 having a high nickel content can be produced.

The temperatures of the obtained metal M1 and slag M2 can be controlled by controlling the heating temperature by increasing or decreasing the fuel heating amount in the burner.

[Recovery process]
The recovery step S4 is a step of separating the metal obtained by reduction and the slag and recovering the metal. As described above, in the reduction treatment in the reduction step S3, the mixture using the movable burner is brought into a molten state and reduced, so that the molten metal M1 and the molten slag M2 are produced. Since the metal M1 has a larger specific gravity and is heavier than the slag M2, each of them naturally separates due to the difference in specific gravity, and the metal accumulates in the bottom of the reduction furnace. Therefore, only the metal can be selectively recovered by removing the metal from the vicinity of the bottom of the reduction furnace and recovering the metal. On the other hand, since the slag M2 floats on the metal M1, it can be recovered by pulling it out from the furnace wall, for example. Since the obtained metal M1 and slag M2 are in a molten state as described above, they can be easily separated and recovered due to the difference in specific gravity.

Alternatively, the metal M1 and the slag M2 may be recovered in a mixed state from one hole in the reduction furnace. By doing so, the structure of the reduction furnace 10 can be simplified and the workability can be improved. When the metal M1 and the slag M2 are extracted from one hole in a mixed state, the recovered metal M1 and the slag M2 can be recovered by cooling, solidifying, and then separating by magnetic separation or the like. can. Since the metal M1 and the slag M2 are already separated when they are in the molten state, the metal M1 and the slag M2 are basically maintained in a separated state even in the solid state, and a method such as magnetic separation is used. However, the metal M1 can be easily recovered.

Since the metal M1 and the slag M2 are already separated when they are in the molten state, the metal M1 and the slag M2 are basically maintained in a separated state even in the solid state, and a method such as magnetic separation is used. However, the metal M1 can be easily recovered.

By easily separating the metal M1 and the slag M2 in this way, the metal M1 can be recovered with a high recovery rate.

≪2-2. Method of smelting nickel oxide ore of the second embodiment ≫
A method for smelting nickel oxide ore of the second embodiment, which is different from the method for smelting nickel oxide ore of the first embodiment, will be described. This embodiment is configured in the same manner as the first embodiment, except that the mode of the burner is different.

This embodiment is characterized in that, instead of changing the ejection position of the flame ejected from the burner, the mixture is subjected to the reduction treatment while changing the ejection direction of the flame. As a result, it is possible to obtain the same effect as the method for smelting nickel oxide ore of the first embodiment.

In the processing section 11 of the reduction furnace 10, a burner 14 is provided above the processing section 11, and the burner 14 is fixed in the reduction furnace at one point. Then, the burner 14 itself can be manually or electrically rotated around one point to change the orientation direction of the flame ejection port while the burner 14 itself is fixed, whereby the flame ejection direction can be changed. Can be changed. At this time, by performing the reduction treatment on the mixture while changing the ejection direction of the flame, the entire mixture can be heated more uniformly, and the mixture can be effectively reduced in a short treatment time.

The method for smelting the oxide ore of the present invention is not limited to a mode in which the mixture is reduced while changing either the ejection position or the ejection direction of the flame ejected from the burner, and is ejected from the burner. The mixture may be reduced while changing both the flame ejection position and the flame ejection direction.

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

<< Examples, Comparative Examples >>
(Mixing process)
Nickel oxide ore as a raw material ore, iron ore, silica sand and limestone as a flux component, a binder, and a carbonaceous reducing agent (coal powder, carbon content: 82% by mass, average particle size: about 63 μm) are added to an appropriate amount of water. Was added and mixed using a mixer to obtain a mixture. Regarding the carbonaceous reducing agent, when the amount required to reduce nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore in just proportion is 100% by mass, 27 It was contained in an amount of mass%.

(Drying process, reduction process)
The obtained mixture was charged into a drying facility as it was without being molded, dried at a temperature of 180 ° C. or higher for 1 hour, and the dried mixture was charged into a reduction furnace (burner furnace) equipped with a burner. .. As the burner, a gas burner using gaseous fuel was used. In the burner furnace, the charged mixture was heated by a burner to be in a molten state and subjected to a reduction treatment. By this reduction treatment, metal and slag in a molten state were generated in the burner furnace, and the slag was separated into the upper layer and the metal was separated into the lower layer due to the difference in specific gravity. In the reduction treatment, the operations were divided into Examples 1 to 9 and Comparative Examples 10 to 11, and the mixture was prepared so that the temperature of the obtained metal and slag was the temperature shown in Table 3 below as the reduction temperature in each operation. Was heated and reduced.

In Examples 1 to 11, as shown in FIG. 2, a burner (movable burner 14) was arranged above the inside of the furnace (processing unit 11). Then, in Examples 1 to 9, the flame ejection port of the movable burner 14 is oriented in the vertical downward direction, and the ejection position is changed in the vertical direction (vertical direction) of the flame while the flame ejection direction is fixed, and the mixture is mixed. Was reduced. Further, in Examples 10 and 11, the flame ejection direction of the movable burner 14 is changed from 0 ° to the angle of the movable range shown in Table 3 below with the vertical downward direction as a reference (0 °). However, the mixture was subjected to a reduction treatment.

On the other hand, in Comparative Examples 1 to 3, the flame ejection position and the ejection direction were fixed, and the mixture was reduced (indicated as "fixed" on the burner in Table 3). In addition, it was confirmed from the inspection port in the furnace that there was no semi-melted mixture adhering to the inner wall of the furnace.

(Recovery process)
The molten metal was extracted from the vicinity of the bottom of the burner furnace and recovered.

(Analysis of the obtained metal)
For each metal sample obtained as described above, the nickel metallization rate, the nickel content in the metal (nickel grade), and the metal recovery rate were analyzed. The analysis results are shown in Table 3 below.

Here, the nickel content in the metal was measured using an ICP emission spectrophotometer (SHIMAZU S-8100), the nickel metal content was measured by the following formula (1), and the nickel content in the metal was described in the following (2). Calculated by the formula.

Nickel metallization rate = Amount of metallized Ni in pellets ÷ (Amount of all nickel in the mixture) × 100 (%) ・ ・ ・ Equation (1) Nickel content in metal = Metallicized Ni in pellets Amount ÷ (total amount of metallic nickel and iron in the mixture) × 100 (%) ・ ・ ・ Eq. (2)

As shown in the results of Table 3, in Examples 1 to 11 in which the mixture was reduced while changing the ejection position and ejection direction of the flame ejected from the burner, the nickel metallization rate and the nickel content in the metal were obtained. Good results were obtained in. From this, it can be seen that the method for smelting oxidized ore according to the present invention can efficiently produce high-quality metal.

Further, in Examples 1 to 11, it was not possible to confirm the adhesion of the semi-melted mixture to the inner wall of the furnace after the reduction treatment. From this, even when the mixture is reduced to obtain a melt, the semi-melt adheres to the mixture by reducing the mixture while changing the flame ejection position and the ejection direction. It can be seen that the decrease in operational efficiency can be suppressed by growing.

10 Reduction furnace 11 Processing unit 12 Equipment inlet 13 Discharge port 14 Movable burner (burner)
M mixture M1 metal M2 slag

Claims (4)

A mixing step of obtaining a mixture containing an oxide ore and a carbonaceous reducing agent,
It has a reduction step of applying a reduction treatment to the mixture in a reduction furnace equipped with a burner.
In the reduction step, a method for smelting an oxidized ore in which the mixture is reduced while changing the ejection position of the flame ejected from the burner. A mixing step of obtaining a mixture containing an oxide ore and a carbonaceous reducing agent,
It has a reduction step of applying a reduction treatment to the mixture in a reduction furnace equipped with a burner.
In the reduction step, a method for smelting an oxidized ore in which the mixture is reduced while changing the ejection direction of the flame ejected from the burner. The method for smelting an oxidized ore according to claim 1 or 2, wherein in the reduction step, the mixture is subjected to a reduction treatment to obtain a melt. The oxide ore is a nickel oxide ore.
The method for smelting an oxide ore according to any one of claims 1 to 3, wherein a ferronickel is produced by subjecting the mixture containing the nickel oxide ore to a reduction treatment.

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