WO2018073891A1

WO2018073891A1 - Ferronickel production method

Info

Publication number: WO2018073891A1
Application number: PCT/JP2016/080843
Authority: WO
Inventors: 俊介持田; 賢三左右田
Original assignee: 日揮株式会社
Priority date: 2016-10-18
Filing date: 2016-10-18
Publication date: 2018-04-26

Abstract

A ferronickel production method characterized in that saprolite is melted and ferronickel is obtained by charging saprolite and a reducing agent from the upper part of a furnace body in a smelting furnace provided with a lance that is immersed inside the starting material and feeding fuel and a combustion improver from the lance while burning the fuel inside the smelting furnace.

Description

Method for producing ferronickel

The present invention relates to a method for producing ferronickel.

Ferronickel (iron nickel alloy) such as nickel pig iron (NPI) is often used as a raw material for stainless steel. Conventionally, ferronickel has been produced in large quantities by reducing an oxide mineral containing iron and nickel using an electric furnace or the like.

Non-Patent Document 1 describes a technique of smelting nickel ore such as nickel sulfide and nickel laterite using a top submerged lance (TSL) furnace.

In Patent Document 1, powdered metal oxide is supplied from a burner into a high-temperature flame and melted in a reaction furnace, and further the metal oxide is reacted with a reducing agent to give metal (iron, chromium, nickel, etc.). The method of obtaining is described.

Non-Patent Document 2 reports the examination items when the capacity is increased in a facility for producing ferronickel by the RKEF (Rotary Kiln Electric Furnace) method using a rotary kiln and an electric furnace.

JP 9-310126 A

According to Non-Patent Document 1, attempts have been made to produce ferronickel using nickel laterite, that is, low-grade limonite (limonite) as a raw material. However, after reducing the ore in the TSL furnace, a step of removing slag is necessary, and the process is complicated.

In the method described in Patent Document 1, even if powdered metal oxide is supplied into the flame, the powder particles are easily discharged into the exhaust gas, and the yield is reduced. However, iron ore containing 2.0 wt% of water (H ₂ O) is used as a raw material, but it has not been studied to use ore with a higher water content as a raw material. When ores with a high water content are supplied into the flame, foaming increases due to the boiling of water, which may adversely affect the stable operation of the reactor.

According to Non-Patent Document 2, since the amount of electric power used is large, it is necessary to attach power generation equipment (coal-fired power generation, LNG thermal power generation, diesel power generation, etc.) to the facility. When a smelter is established near the ore production area, ore transportation costs can be reduced, but power generation equipment construction and operation costs are incurred, and the profitability of the smelter decreases.

The present invention has been made in view of the above circumstances, and provides a method for producing ferronickel capable of smelting nickel oxide mineral at a lower cost even in remote areas where power supply is low. Let it be an issue.

According to a first aspect of the present invention, saprolite and a reducing agent are charged into a smelting furnace including a lance immersed in the raw material from the upper part of the furnace body, and fuel and an auxiliary combustor are supplied from the lance. A ferronickel production method characterized in that ferronickel is obtained by melting the saprolite by burning fuel in the smelting furnace.

According to a second aspect of the present invention, the water content of saprolite supplied to the smelting furnace is in the range of 21.5 to 22.5 wt% on a moisture basis. This is a method for producing ferronickel.

According to a third aspect of the present invention, any of the inner peripheral surfaces of the smelting furnace in contact with the molten metal and slag is any of MgO—C, MgO—Cr ₂ O ₃ and MgO, or A ferronickel production method according to the first or second aspect, characterized in that a refractory material is provided as a combination thereof.

According to a fourth aspect of the present invention, any one of the first to third aspects is characterized in that the carbon dioxide in the exhaust gas is removed by passing the exhaust gas of the smelting furnace twice through the amine-based solution. This is a method for producing ferronickel.

According to a fifth aspect of the present invention, ferronickel obtained from the smelting furnace is transferred to a refining furnace, and oxygen is blown in the refining furnace and flux (for example, a melting aid such as quartz) is added from the ferronickel. The method for producing ferronickel according to any one of the first to fourth aspects, comprising a step of removing an impurity element.

According to the first aspect, by using saprolite whose nickel quality is higher than that of limonite as raw material ore, the reduced metal component can be easily separated from the slag, and ferronickel can be produced at low cost. Become. By burning the fuel in the smelting furnace and melting the ore, it is possible to ease the location conditions of the production facility without requiring electric power to melt the ore (that is, it is not necessary to newly install or enhance the power generation facility) Become). By supplying the fuel and the auxiliary combustor from the lance into the furnace, the raw material is agitated and the reduction reaction can be made more efficient.

According to the 2nd aspect, the ore in a smelting furnace is hard to be discharged | emitted in waste gas, and foaming of the molten metal and slag can be suppressed.

According to the third aspect, even if the temperature fluctuation in the smelting furnace is large, the deterioration of the furnace body can be suppressed and long-term stable operation can be achieved. The inner peripheral surface of the smelting furnace becomes difficult to get wet with the molten slag, and at the same time, thermal shock resistance is ensured by the action of graphite (C) having a high thermal conductivity and a low thermal expansion coefficient.

According to the fourth aspect, even when a large amount of carbon dioxide is generated by the combustion of fuel, it is possible to efficiently separate the carbon dioxide from the exhaust gas and suppress the discharge of carbon dioxide into the atmosphere (outside air). In addition, carbon dioxide absorbed in the amine-based solution is easily released into the gas phase by heating the amine-based solution, so that the amine-based solution can be reused for the recovery of carbon dioxide in the exhaust gas. In addition, carbon dioxide released into the gas phase can be recovered at a high concentration.

According to the fifth aspect, impurities such as phosphorus (P), sulfur (S), silicon (Si), and carbon (C) can be removed from the metal component as a slag or gas component. Ferronickel can be obtained.

It is a schematic diagram which shows an example of a smelting furnace. It is a schematic diagram which shows an example of a refinement | purification furnace. It is a schematic diagram which shows the 1st example of a preliminary drying apparatus. It is a schematic diagram which shows the 2nd example of a preliminary drying apparatus. It is a schematic diagram which shows an example of the system which isolate | separates a carbon dioxide from waste gas.

Hereinafter, the ferronickel production method (smelting method) of the present invention will be described based on a preferred embodiment.

(First embodiment)
In the smelting method of the first embodiment, ferronickel is manufactured by using a saprolite as a raw material in a smelting furnace including a lance.

As a raw material of ferronickel, saprolite containing iron oxide and nickel oxide is used among nickel oxide ores. Saprolite is in the process of generating clayey ore by the weathering of rock, and on the rock is located in the lower part of soil mainly composed of mulch and low-grade limonite (limonite). In the tropical region, silica and base are leached in the process of rock weathering, and metal elements such as iron (Fe) and nickel (Ni) are concentrated in saprolite. When weathering proceeds more than saprolite, limonite is produced. Limonite has a higher Fe ratio and lower Ni quality than saprolite.

By using saprolite as a raw material among nickel oxide minerals, separation of metal components and slag obtained by smelting becomes easy. For this reason, it becomes possible to produce ferronickel at low cost. The Ni content contained in saprolite is preferably 1.6 wt% or more on the dry basis excluding moisture. Examples of the Ni content include, but are not limited to, 1.8 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, and the like.

Figure 1 shows an example of a smelting furnace. In this embodiment, the smelting furnace 10 provided with the lance 12 immersed in the inside of the mixture 16, such as a raw material, from the upper part of the furnace body 11 is used. An example of such a smelting furnace 10 is a TSL furnace. In the furnace body 11, ore (saprolite) and a reducing agent are charged as raw materials. The mixture 16 during smelting may contain one or more raw materials such as ore, reducing agent, molten metal, and slag.

Examples of the reducing agent include substances that include one or both of a carbon source and a hydrogen source, and generate carbon dioxide or water by oxidation. Specific examples of the reducing agent include carbon such as coal, coke, and charcoal, hydrocarbon such as natural gas and heavy oil, and reducing gas such as hydrogen (H ₂ ). Although there are various types of coal, it is not particularly limited and can be selected from anthracite, bituminous coal, lignite, lignite, and the like. One reducing agent may be used, or two or more reducing agents may be used in combination.

A flux may be added to the raw material in order to lower the melting point of the mixture 16. As the flux used in the smelting process, one or more of quartz (SiO ₂ ), calcium oxide (CaO), calcium hydroxide (Ca (OH) ₂ ), calcium carbonate (CaCO ₃ ), iron scrap, etc. Is mentioned.

A lance 12 is provided above the furnace body 11 in order to burn the fuel in the smelting furnace 10. Fuel and auxiliary fuel can be supplied through the lance 12. Examples of the fuel include carbon such as coal, coke, and charcoal, hydrocarbon such as natural gas and heavy oil, biofuel, and waste plastic. One type of fuel may be used, or two or more types of fuel may be used in combination. The fuel is preferably supplied to the lance 12 as a fluid such as liquid, gas or powder.

Examples of the auxiliary combustor include oxygen-containing gas such as oxygen (O ₂ ) and oxygen-enriched air. One type of auxiliary combustion agent may be used, or two or more types of auxiliary combustion agents may be used in combination.

The lance 12 may have a multi-pipe structure such as a double pipe in order to supply the fuel and the auxiliary combustor separately. A mixture of fuel and combustion aid is blown from the lance 12 into the mixture 16. Since the lower part of the lance 12 is submerged in the mixture 16, the mixture 16 is agitated by the injected fuel, the auxiliary combustor, and the gas generated by the combustion thereof, so that the reduction reaction can be made efficient. it can.

In order to supply substances such as ore, a reducing agent, and flux into the furnace body 11, a port 13 may be provided on the top of the furnace body 11. However, some or all of the ore, the reducing agent, the flux, and the like can be supplied from the lance 12 into the furnace body 11. It is also possible to supply a part of the fuel or auxiliary fuel from the port 13.
The port 13 only needs to be able to supply a material onto the mixture 16 by charging or the like, and does not need to be immersed in the mixture 16. The smelting furnace 10 may have ports 13 at two or more locations.

By burning the fuel in the smelting furnace 10, the ore (saprolite) melts and reacts with the reducing agent to obtain ferronickel. The exhaust gas generated at the time of combustion is discharged from an exhaust pipe 15 provided at the upper part of the smelting furnace 10.
It is also possible to recover the thermal energy in the generated exhaust gas with an exhaust heat boiler and use this energy or water vapor for pre-drying of saprolite (see, for example, the third embodiment).

For example, when the reducing agent is carbon (C), the oxide in the ore is reduced to a metal by the following reaction formula.

NiO _(l) + C _(s) → Ni _(l) + CO _(g)
FeO _(l) + C _(s) → Fe _(l) + CO _(g)

In the reaction formula, “ _(s) ” represents a solid state, “ _(l) ” represents a liquid state, and “ _(g) ” represents a gas state.

Further, carbon monoxide (CO) generated by the metal reduction reaction with carbon is further oxidized to generate carbon dioxide (CO ₂ ) as shown in the following reaction formula.

CO _(g) + (1/2) O _{2 (g)} → CO _{2 (g)}

A molten metal containing molten metal and slag is generated in the furnace body 11. Metal components with high specific gravity (Ni, Fe, etc.) collect at the bottom of the molten metal, and slag components (SiO ₂ , MgO, etc.) with low specific gravity collect at the top of the molten metal. Since the metal component and the slag component are separated in the furnace body 11, ferronickel can be obtained by removing the metal component from the discharge port 14. The smelting furnace 10 may have discharge ports 14 at two or more locations. A discharge port for discharging the slag component may be provided separately from the discharge port for discharging the metal component.

Reducing the location conditions of the production facility without the need for electric power to melt or reduce the ore by obtaining the heat energy that causes the reduction reaction to proceed while burning the fuel in the smelting furnace 10 Can do. The temperature of the mixture 16 melted in the furnace body 11 is preferably 1400 to 1650 ° C., and more preferably 1450 to 1600 ° C., for example.

As described above, when a TSL furnace is adopted as the smelting furnace 10, the mixture in the furnace body 11 is effectively agitated by the granules supplied from the lance 12. However, the molten metal surface level changes greatly, and the temperature of the inner peripheral surface of the smelting furnace 10 such as the furnace body 11 frequently fluctuates. For this reason, it is preferable to provide one or more refractories such as MgO—C, MgO—Cr ₂ O ₃ and MgO on the inner peripheral surface of the smelting furnace 10. These refractories have a high melting point, are basic, and have excellent basic resistance even when in contact with molten slag. For example, when refractory bricks such as MgO-C are installed on the inner peripheral surface of the furnace body 11, it is easy to ensure the thickness of the refractory, and the damaged refractory can be inspected and replaced for each brick. Is possible. It is also possible to make the refractory a uniform coating layer in the plane.
The range in which the refractory is provided in the furnace preferably includes the side surface and the bottom surface in contact with the molten metal and slag. It is also possible to combine two or more refractories. For example, two or more kinds of refractories may be divided and installed at different locations in the smelting furnace 10. It is also possible to install two or more refractories in the same location in the smelting furnace 10.

In particular, when an MgO—C refractory is used, deterioration of the furnace body 11 is suppressed even if the temperature fluctuation in the smelting furnace 10 is large, and long-term stable operation can be achieved. The inner peripheral surface of the smelting furnace 10 is not easily wetted by the molten slag, and at the same time, thermal shock resistance is ensured by the action of graphite (C) having a high thermal conductivity and a low thermal expansion coefficient.

(Second Embodiment)
In the smelting method of the second embodiment, the ferronickel obtained from the smelting furnace of the first embodiment is transferred to the refining furnace, and the impurity element is removed from the ferronickel by blowing oxygen and adding flux in the refining furnace. (Purification step).

FIG. 2 shows an example of the refining furnace 20. In the refining furnace 20, molten metal 25 containing ferronickel as a main component is placed in the pan portion 21, and a flux is supplied from the hopper 23 to the pan portion 21, and a gas such as oxygen is blown into the pan portion 21 from the gas supply portion 24. It is a configuration. It is preferable that the pan portion 21 is disposed on the carriage 22 because it is easy to move. In order to make it easy to take out the molten metal 25 from the pan portion 21, it is preferable that the refining furnace 20 includes a mechanism (not shown) for tilting the pan portion 21. When the pan portion 21 is tilted on the cart 22, the bottom surface of the pan portion 21 may be tilted with respect to the mounting surface of the cart 22.

As the flux used in the refining process, one or more of quartz (SiO ₂ ), calcium oxide (CaO), calcium hydroxide (Ca (OH) ₂ ), calcium carbonate (CaCO ₃ ), iron scrap, etc. Can be mentioned. When flux is used in the smelting process, the flux used in the refining process may be the same as or different from the flux used in the smelting process.

By blowing oxygen into the molten metal, phosphorus (P), silicon (Si), and carbon (C) contained in the metal component can be removed from the metal component as slag or gas component. An example of the reaction formula at this time is shown below. Note that “(metal)” represents a component included in the metal component, and “(slag)” represents a component included in the slag component.

Si _(metal) + O _{2 (g)} → SiO _{2 (slag)} + Heat
2C _(metal) + O _{2 (g)} → 2CO _(g) + Heat
4P _(metal) + 5O _{2 (g)} + 6CaO _(slag) → 2Ca ₃ (PO ₄ ) _{2 (slag)}

Also, silicon (Si) and aluminum (Al) can be added for deoxidation (killing), and sulfur (S) can be reacted with a flux (solvent) to be removed as slag. The reaction formula at this time is shown below.

2O _(metal) + Si _(metal) → SiO _{2 (slag)}
3O _(metal) + 2Al _(metal) → Al ₂ O _{3 (slag)}
S _(metal) + CaO _(slag) → CaS _(slag) + O _(metal)

(Third embodiment)
The smelting method of the third embodiment includes a step of pre-drying the raw material ore (pre-drying step) before supplying the raw material ore (saprolite) to the smelting furnace of the first embodiment. In order to produce ferronickel with the desired chemical composition with high yield and productivity, the raw ore is dried to a predetermined moisture content, and the discharge of the raw ore to the exhaust gas system and the foaming in the smelting furnace are suppressed. It is desirable to do.

FIG. 3 shows an example of a steam dryer as a first example of the preliminary drying apparatus. The preliminary drying apparatus 30 supplies the raw ore crushed in the pulverization unit 31 to the drying unit 32, and passes the water vapor generated in the steam generation unit 33 in the longitudinal direction of the drying unit 32, thereby drying from the discharge unit 34. It is a device that discharges the processed ore.

FIG. 4 shows an example of a jaw crusher as a second example of the preliminary drying apparatus. The preliminary drying apparatus 40 inputs raw material ore from an upper path 41 of the pulverizing unit 42, pulverizes the raw material ore by a jaw (not shown) provided inside the pulverizing unit 42, and a lower path 43 of the pulverizing unit 42. Is a device that dries the ore from the discharge unit 44 by supplying hot air from the outlet and drying the ore.

Preliminary drying apparatus is not particularly limited, and in addition to the above, a rotary dryer, an impact dryer, or the like can also be used.

The water content of saprolite supplied to the smelting furnace through the preliminary drying step is preferably in the range of 21.5 to 22.5 wt% (wet basis). The moisture content on the moisture basis is represented by the left side w of the following equation, where Ws is the weight of solids and Ww is the weight of moisture.

w = (Ww / (Ws + Ww)) × 100 (%)

When the moisture content is equal to or higher than the lower limit, an appropriate amount of water is secured in the smelting furnace, and the pulverized raw material ore is less likely to be discharged from the smelting furnace into the exhaust gas. Moreover, when a moisture content is below the said upper limit, excessive water content can be avoided and foaming of the molten metal and slag can be suppressed.
The water content of the raw material ore before preliminary drying is, for example, about 30 to 40 wt% (wet basis).

(Fourth embodiment)
The smelting method of the fourth embodiment includes a step of removing carbon dioxide (CO ₂ ) by passing the exhaust gas (combustion gas) discharged from the smelting furnace of the first embodiment twice or more through the amine-based solution.

FIG. 5 shows an example of the CO ₂ removal device 50. A CO ₂ absorber 51 is provided in the middle of the exhaust gas paths 52 and 53. The exhaust gas paths 52 and 53 are connected to the exhaust pipe 15 of the smelting furnace 10.

A first flow path 54 is installed in communication between the middle stage and the lower stage of the CO ₂ absorber 51. Inside the first flow path 54, an amine-based solution flows as a CO ₂ absorbent. The amine-based solution at the stage of exiting from the lower stage of the CO ₂ absorption unit 51 is a rich solution having a large amount of CO ₂ absorption, but the amine-based solution is heated in the first diffusion unit 55 provided in the middle of the first flow path 54. And part of the CO ₂ contained in the amine-based solution is released into the gas phase.

Amine solution through the first stripping unit 55, become the semi-lean solution CO ₂ absorption amount is reduced, is supplied to the middle stage of the CO ₂ absorbing section 51. The semi-lean solution absorbs most of CO ₂ (for example, about 70%) from the exhaust gas passing through the CO ₂ absorbing portion 51.

Further, the CO ₂ removal device 50 is provided with a second flow path 56 in communication between the first flow path 54 that has passed through the first diffusion section 55 and the upper stage of the CO ₂ absorption section 51. An amine-based solution branched from the first flow path 54 flows inside the second flow path 56. The amine-based solution branched from the first flow path 54 is a semi-lean solution as described above. However, the amine-based solution is heated in the second diffusion portion 57 provided in the middle of the second flow path 56, and the amine-based solution. CO ₂ contained in is released into the gas phase.

The amine-based solution that has passed through the second diffusion unit 57 becomes a lean solution in which the amount of CO ₂ absorption is greatly reduced, and is supplied to the upper stage of the CO ₂ absorption unit 51. By this lean solution, from the exhaust gas passing through the CO ₂ absorbing section 51, the semi-lean solution many CO ₂ remaining in the exhaust gas is absorbed without being absorbed. Thereby, 90% or more or 99% or more of CO ₂ can be removed from the exhaust gas as compared with the exhaust gas before entering the lower stage of the CO ₂ absorber 51.

By providing a process for removing CO ₂ in two or more stages as described above, even if a large amount of carbon dioxide is generated by the combustion of fuel, carbon dioxide is efficiently separated from the exhaust gas, and is released into the atmosphere (outside air). The emission of carbon dioxide can be suppressed. In addition, since carbon dioxide absorbed in the amine-based solution is easily released into the gas phase by heating the amine-based solution, the amine-based solution can be reused for the recovery of carbon dioxide in the exhaust gas. In addition, carbon dioxide released into the gas phase can be recovered at a high concentration.

Examples of the amine-based solution include an aqueous solution of an organic amine compound. Examples of amines include primary amines, secondary amines, and tertiary amines. Among these, it can be selected in consideration of performance such as CO ₂ absorption capacity and avoidance of equipment corrosion. Specific examples include methyldiethanolamine (MDEA) and monoethanolamine (MEA). In order to increase the absorption rate of CO ₂ , an additive such as an activator may be added to the amine-based solution.

The CO ₂ diffused from the first diffuser 55 and the second diffuser 57 can be recovered as dry ice by compression solidification and used as a cooling agent or the like. Since the vapor phase containing CO ₂ is accompanied by high-temperature water vapor, even if the residual heat of CO ₂ diffused from the second diffusion unit 57 is used as an auxiliary to the heat source when the rich solution is heated in the first diffusion unit 55, Good.

As mentioned above, although this invention has been demonstrated based on suitable embodiment, this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary of this invention. Examples of modifications include addition, omission, and substitution. It is possible to combine the configurations of two or more embodiments from the first to fourth embodiments.

Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited only to these Examples.

As an example of the present invention, the result of a test example using a small crucible will be described.
The raw material nickel oxide ore (raw material ore) was saprolite from the Philippines, and its chemical composition was as shown in Table 1. Here, LOI represents ignition loss. Moreover, the moisture content calculated | required from the weight after drying this raw material ore to a completely dry state was 30 wt% (humidity reference | standard).

(Test Example 1)
First, as a preliminary drying step, 1000 g of raw material ore was placed in a shelf-type dryer and dried at an ambient temperature of 110 ° C. for 0.5 hour. As a result, the water content was 22.2 wt% (wet basis). In addition, about this moisture content, preferable conditions were employ | adopted based on Test Example 2 mentioned later. Next, 55.0 g of Indonesian bituminous coal as a reducing agent was added to the raw ore after preliminary drying, and mixed for 10 minutes in a stainless mortar.

On the other hand, as a model of the smelting furnace, an Inconel (registered trademark) pipe having an inner diameter of 100 mm, a height of 150 mm, made of MgO—C refractory (92 wt% MgO, 8 wt% C) and an inner diameter of 10 mm extending from the top to the inside is used. A prepared crucible (melting reduction crucible) was prepared, and this melting reduction crucible was placed in a small electric furnace and kept soaked at an ambient temperature of 1450 ° C. for 1.0 hour.

The mixture of raw ore and bituminous coal obtained by mixing in the described mortar was charged from the top of the melting and reducing crucible held soaked in a small electric furnace and allowed to stand for 1.0 hour. Preheated. Here, the electric furnace was turned off, and the mixture was allowed to stand for another hour while continuously supplying combustion air having an oxygen concentration of 75% and powdered bituminous coal from the pipe. As a result, the mixture melted to obtain a molten metal. Was separated at the bottom and the slag component at the top. The smelting reduction crucible was broken and only the metal components after smelting were taken out from the smelting reduction crucible.

As a refining furnace model, a crucible made of MgO—C refractory (92 wt% MgO, 8 wt% C) (refining crucible) having an inner diameter of 40 mm and a height of 60 mm was prepared and smelted in the refining crucible. When the later metal component was transferred, the weight of the metal component was 53.3 g. The obtained metal component was ferronickel, and its chemical composition was as shown in Table 2.

5.0 g of calcium oxide (CaO) was added as a flux to the purification crucible, and 95% pure oxygen (O ₂ ) was blown into the crucible for purification. Next, 0.5 g of aluminum (Al) was added, and the inside of the purification crucible was set to a deoxidizing atmosphere. As a result, 48.4 g of ferronickel having the chemical composition shown in Table 3 could be obtained.

By comparing Table 2 and Table 3, silicon (Si), carbon (C), phosphorus (P), and sulfur (S) in the metal component were removed, and ferronickel was refined to the desired chemical composition. I was able to confirm.

(Test Example 2)
The moisture content (wet basis) of the raw ore after being dried by the shelf dryer described in Test Example 1 was set every 0.5 wt% in the range of 21.0 to 23.0 wt%. The smelting process was implemented like the test example 1 using the raw ore of each moisture content. Under each condition, discharge of raw ore into the exhaust gas generated in the melting reduction crucible (Carry Over) and generation of foaming of the raw ore in the melting reduction crucible (Foaming) were investigated. The results are shown in Table 4.

“Emissions into exhaust gas” tended to be reduced as the moisture content of the raw material ore increased, and “foaming of the raw material ore” tended to decrease as the moisture content of the raw material ore decreased. It was found that both “exhaust into exhaust gas” and “foaming of raw ore” are most reduced when the moisture content of the raw ore is in the range of 21.5 to 22.5 wt%.

(Test Example 3)
By changing the material of the refractory material of the melting reduction crucible described in Test Example 1, the influence of the material (chemical composition) of the refractory material on the damage amount of the refractory material was investigated. The results are shown in Table 5. The amount of damage to the refractory material was a ratio to the amount of nickel smelted.

For MgO—Cr ₂ O ₃ refractories, MgO refractories, and MgO—C refractories, the amount of damage to the refractory was measured from the weight loss of the smelting reduction crucible after the purification process. We were able to confirm that the amount of damage was small and could be used. Among them, it was found that the damage amount of the MgO—C refractory (92 wt% MgO, 8 wt% C) was the smallest.

According to the present invention, it is possible to construct and operate a smelter even in remote areas where power supply is low. Ferronickel produced according to the present invention can be used as a raw material for stainless steel and the like.

DESCRIPTION OF SYMBOLS 10 ... Smelting furnace, 11 ... Furnace body, 12 ... Lance, 13 ... Port, 14 ... Discharge port, 15 ... Exhaust pipe, 16 ... Mixture, 20 ... Refining furnace, 21 ... Pot part, 22 ... Dolly, 23 ... Hopper , 24 ... Gas supply unit, 25 ... Molten metal, 30 ... Pre-drying device, 31 ... Crushing unit, 32 ... Drying unit, 33 ... Steam generating unit, 34 ... Discharge unit, 40 ... Pre-drying device, 41 ... Upper path, 42 Pulverizing section, 43 ... lower path, 44 ... discharge section, 50 ... CO2 removal device, 51 ... CO2 absorption section, 52, 53 ... exhaust gas path, 54 ... first flow path, 55 ... first diffusion section, 56 ... first 2 flow paths, 57 ... 2nd diffusion part.

Claims

Saprolite and reducing agent are charged into a smelting furnace equipped with a lance immersed in the raw material from the upper part of the furnace body, and fuel is burned in the smelting furnace while supplying fuel and a combustor from the lance. To produce the ferronickel by melting the saprolite.
The method for producing ferronickel according to claim 1, wherein the water content of saprolite supplied to the smelting furnace is in the range of 21.5 to 22.5 wt% on a moisture basis.
Of the inner peripheral surface of the smelting furnace, a refractory material that is either MgO—C based, MgO—Cr 2 O 3 based, MgO based, or a combination thereof is provided on the surface that contacts molten metal and slag. The method for producing ferronickel according to claim 1 or 2.
The method for producing ferronickel according to any one of claims 1 to 3, wherein the exhaust gas from the smelting furnace is passed through an amine-based solution twice or more to remove carbon dioxide in the exhaust gas.
The ferronickel obtained from the smelting furnace is transferred to a refining furnace, and the impurity element is removed from the ferronickel by blowing oxygen and adding flux in the refining furnace. The manufacturing method of the ferronickel of any one of these.