WO2020165974A1

WO2020165974A1 - Sulfation roasting method

Info

Publication number: WO2020165974A1
Application number: PCT/JP2019/005100
Authority: WO
Inventors: 賢三左右田
Original assignee: 日揮グロ－バル株式会社
Priority date: 2019-02-13
Filing date: 2019-02-13
Publication date: 2020-08-20
Also published as: PH12021550534A1; AU2019429311A1; JPWO2020165974A1

Abstract

In a process in which feedstock including nickel and iron is sulfation roasted, a burner is arranged in a roasting furnace, sulfur is supplied to the burner and combusted, and a sulfur oxide is generated inside the roasting furnace.

Description

Sulfation roasting method

The present invention relates to a sulfated roasting method.

Conventionally, nickel sulfate compounds have been used as raw materials for various nickel compounds or metallic nickel for electrolytic nickel plating, electroless nickel plating, catalyst materials, etc. In recent years, it is expected that demand for secondary batteries using a nickel compound or metallic nickel as a positive electrode material will increase as a power source for transportation equipment such as electric vehicles and electronic equipment. In order to obtain a high-performance secondary battery, stable supply of high-purity nickel sulfate compound is desired.

Impurities that may be contained in low-purity nickel compounds include other metal compounds such as iron, copper, cobalt, manganese, and magnesium. Conventionally, as a method for obtaining a high-purity nickel compound, there are a method of dissolving metallic nickel whose nickel purity is increased by an electrolytic extraction method with a sulfuric acid solution, and a solvent extraction method. In the solvent extraction method, another metal compound is selectively extracted and removed, or a nickel compound is selectively extracted and taken out. In either case, a special agent was required to selectively extract a specific metal ion, resulting in high cost.

As a method for producing nickel sulfate, a method of exchanging the anion of a nickel compound with a sulfate group by an ion exchange method and a method of dissolving nickel metal powder in a sulfuric acid solution while generating hydrogen gas are also known. Further, Patent Document 1 describes a method of obtaining water-soluble nickel sulfate by subjecting green nickel oxide powder having a specific gravity of more than 6.30 to heat treatment in sulfuric acid and then leaching with hot water. ing. In Patent Document 1, as a sulfuric acid used for the heat treatment, a sulfuric acid solution having a concentration of 30% to 60% (claims 1 to 5) and concentrated sulfuric acid having a concentration of 95% (claims 6 to 7) are mentioned. When concentrated sulfuric acid having a concentration of 95% is used in Patent Document 1 (Examples 7 to 9), a high temperature of 275° C. or higher is required.

U.S. Pat. No. 3,002,814

An object of the present invention is to provide a sulfation roasting method capable of treating a raw material containing nickel and iron by a dry smelting method.

A first aspect of the present invention is to install a burner in a roasting furnace and supply sulfur to the burner for combustion in a step of performing sulfation roasting of a raw material containing nickel and iron in the roasting furnace. The sulfurization and roasting method is characterized in that sulfur oxides are generated by.

A second aspect of the present invention is the sulfation roasting method of the first aspect, characterized in that the sulfur is supplied in liquid form to the burner by air pressure.

A third aspect of the present invention is characterized in that the concentration of sulfur oxide in the roasting furnace is measured, and the amount of sulfur or air supplied to the burner is controlled based on the measured value. It is the sulfated roasting method of the 1st or 2nd aspect.

A fourth aspect of the present invention is to measure the concentration of sulfur oxides in the exhaust gas discharged from the roasting furnace, and control the amount of sulfur or air supplied to the burner based on this measurement value. It is the sulfated roasting method of the first to third aspects characterized.

A fifth aspect of the present invention is characterized in that the raw material is a fluidized bed in the roasting furnace, and the burner is installed above a position where a roasted product is taken out from the roasting furnace. It is the sulfated roasting method of the fourth aspect.

In a sixth aspect of the present invention, the burner is installed along the wall surface of the roasting furnace, and sulfur is supplied in a direction along the inner wall surface of the roasting furnace and in a direction intersecting the vertical direction. A sulfated roasting method according to a fifth aspect, characterized in that

A seventh aspect of the present invention is the sulfated roasting method according to the fifth or sixth aspect, wherein the burner is installed below a position where the raw material is supplied to the roasting furnace.

According to an eighth aspect of the present invention, the oxygen partial pressure and the sulfur dioxide partial pressure are controlled such that nickel sulfate is thermodynamically more stable than nickel oxide in the Ni—S—O system and is oxidized in the Fe—S—O system. The sulfated roasting method according to any one of the first to seventh aspects is characterized in that the conditions are such that iron is thermodynamically more stable than iron sulfate.

According to the first aspect, since the raw material containing nickel and iron is treated by the dry smelting method, it is not necessary to use liquid sulfuric acid and the treatment is easy. Furthermore, since sulfur is supplied to the burner and burned to generate sulfur oxides in the roasting furnace, it becomes easy to control the conditions of the sulfate roasting.

According to the second aspect, since sulfur is supplied in liquid form to the burner by air pressure, sulfur can be easily transported and combustion control in the burner can be facilitated. In addition, since sulfur is supplied to the burner in a liquid state, it is difficult for the supply portion to be abraded by the sulfur.

According to the third aspect, it is possible to easily control the excess and deficiency of sulfur oxides in the roasting furnace.

According to the fourth aspect, the amount of sulfur required for roasting is supplied by controlling the concentration of sulfur oxides in the roasting furnace in consideration of the amount of sulfur oxides flowing out into the exhaust gas. Can be prevented from being excessively supplied.

According to the fifth aspect, when the raw material is a fluidized bed in the roasting furnace, the device becomes smaller than when using a stirring type roasting furnace, a rotary furnace type roasting furnace, or the like. In addition, by installing the burner above the position where the roasted product is taken out, the flow of the combustion gas from the fluidized bed and the burner is less likely to interfere with each other.

According to the sixth aspect, the combustion gas from the burner generates a swirling flow that flows along the inner wall surface of the roasting furnace with the substantially vertical direction as the central axis, and the floating layer formed above the fluidized bed. The sulfur oxide contained in the combustion gas can be easily reacted with the raw material without obstructing the flow of the raw material in the above.

According to the seventh aspect, the sulfur oxides contained in the combustion gas from the burner easily come into contact with the raw material, so that the reaction can be promoted.

According to the eighth aspect, since the nickel content of the raw material is converted to nickel sulfate and the conversion of iron content to iron sulfate is suppressed, the consumption of sulfur content by the iron content is suppressed and the production efficiency of nickel sulfate is increased. Can be improved.

It is a system block diagram which shows the outline of the sulfation roasting method by embodiment. It is a cross-sectional view of the roasting furnace in the embodiment. FIG. 2 is a conceptual state diagram of Ni—S—O system and Fe—S—O system.

In the sulfation roasting method of the present embodiment, the roasting target is roasted in a roasting furnace to obtain a roasted product. Examples of the object to be roasted include nickel-containing raw materials. The roasted product contains a sulfate such as nickel sulfate.

The nickel-containing raw material may be a nickel compound or metallic nickel as long as it contains nickel element. The nickel compound is not particularly limited, but examples thereof include nickel salts such as nickel oxide, nickel hydroxide, nickel sulfide, and nickel chloride. The nickel compound may be a hydrate. The metallic nickel may be a nickel alloy such as ferronickel. When metallic nickel (a simple substance or an alloy) is used as a nickel-containing raw material, shots obtained by slicing molten metal into small pieces may be used. Nickel ore can also be used as the nickel-containing raw material. Examples of the nickel ore include one or more of nickel oxide ore and nickel sulfide ore. A nickel matte containing nickel sulfide as a main component can also be used as the nickel-containing raw material.

Examples of the nickel mat include a composition (weight ratio) in which Ni is 45 to 55%, Fe is about 20%, S is 20 to 25%, and Co is about 1% or less. Further, as the nickel matte whose nickel concentration is increased in the converter, for example, there is a composition (weight ratio) in which Ni is about 78%, Co is about 1%, Fe is about 1%, and S is about 20%. This nickel mat is in a state where Ni ₃ S ₂ and metallic nickel (Ni) are mixed due to the amount of sulfur content. Examples of ferronickel include a composition (weight ratio) in which Ni is 18 to 23%, Co is about 1%, and Fe is 76 to 81%.

The nickel oxide ores include laterite ores containing nickel such as limonite and saprolite. The limonite may be a limonite having a low iron content or a limonite having a high iron content, and the saprolite may have a high nickel content (for example, a Ni content of 1.8 wt% or more) or a low nickel content (for example, a low nickel content. (Less than 1.8 wt%) Saprolite may be used. Examples of the nickel sulfide ore include iron sulfate nickel ore (Pentland ore), acicular nickel ore, chalcopyrite containing nickel, and pyrrhotite containing nickel.

The nickel-containing raw material in the roasting step preferably contains at least one selected from the group consisting of nickel sulfide ore, nickel oxide ore, nickel sulfide, nickel matte, nickel oxide, and ferronickel. The nickel-containing raw material may not contain iron, but in many cases iron coexists with nickel. The iron content is separated from the nickel sulfate compound in a later step, but from the viewpoint of energy consumption, the smaller the iron content in the raw material, the more desirable. Although it is possible to treat even if the iron content is higher than the nickel content, it is preferable that the iron content is lower than the nickel content. The nickel-containing raw material is not limited to one type, and two or more types may be used. When using two or more kinds of nickel-containing raw materials, these raw materials may be mixed and supplied separately. When sulfating and roasting a nickel-containing raw material, a nickel-containing raw material containing no sulfur may be used, and/or a nickel-containing raw material containing a sulfur content as at least a part of the raw material, for example, nickel sulfide ore, nickel. Sulfide, nickel matte or the like may be used.

Prior to the roasting process, it is preferable to reduce the particle size of the nickel-containing raw material by operations such as shredding, crushing and abrasion. Since the reaction starts from the surface of the nickel-containing raw material in the roasting step, the smaller the particle size of the nickel-containing raw material, the shorter the reaction time, which is preferable. The crushing means is not particularly limited, but one or more kinds such as a ball mill, a rod mill, a hammer mill, a fluid energy mill and a vibration mill can be used. The particle size after pulverization is not particularly limited. When a nickel-containing raw material such as limonite ore is available in the form of fine particles, it may be supplied to the roasting step as it is.

Before performing the sulfation roasting step of the present embodiment, an oxidizing roasting step may be provided for the purpose of oxidizing iron, sulfur, etc. contained in the nickel-containing raw material. In this oxidation roasting process, O ₂ gas or the like may be supplied as an oxidant. The oxidation roasting step may be performed in the same roasting furnace as the sulfate roasting step, or an oxidation roasting furnace different from the sulfate roasting step may be provided. When another oxidation roasting furnace is provided, the roasting product of the oxidation roasting furnace may be supplied as a raw material to the sulfation roasting furnace.

Examples of the roasting furnace for performing the sulfation roasting include a stirring roasting furnace, a rotary furnace roasting furnace, and a fluidized roasting furnace having a fluidized bed. Regarding roasting of ores and the like, conventionally, sulfated roasting using a stirring type roasting furnace or a rotary furnace type roasting furnace is performed after roughly crushing the mined ore. In this case, the burden of pre-treating the object to be roasted is small and the rotation speed is slow, but the reaction speed is slow and the apparatus becomes large. Therefore, a fluidized roasting furnace of a type in which a to-be-roasted object is roasted while being floated with combustion air and flowing has become popular. By adopting a fluidized roasting furnace, the device can be downsized.

FIG. 1 shows a schematic configuration of a system for performing the sulfation roasting method according to this embodiment. In this embodiment, the case where the roasting furnace 10 is a fluidized roasting furnace is illustrated. It should be noted that FIG. 1 is a simplified conceptual diagram, and does not necessarily show an optimum state or value with respect to relationships such as shape, position, size, angle, ratio, and the like. A gas inlet 12 is provided below the furnace body 11 of the roasting furnace 10, and a gas outlet 13 is provided above the furnace body 11. Above the gas inlet 12, a gas dispersion plate 14 that crosses the furnace body 11 in the radial direction is provided. A supply port 15 for the roasting target and a takeout port 16 for the roasted product are provided on the side of the furnace body 11. In the case of this embodiment, the supply port 15 is provided above the outlet 16. When the roasted product has a higher density (specific gravity) than the roasting target, the roasting product gathers on the lower side (on the gas dispersion plate 14) of the roasting target and flows on the gas dispersion plate 14. The layer P1 is formed. Then, the roasted products that have reached the outlet 16 are sequentially discharged. Therefore, by disposing the take-out port 16 below the supply port 15, the fluidized bed P1 does not hinder the supply of the roasting target and promotes the take-out of the roasted product.

The height of the supply port 15 and the take-out port 16 may be approximately the same as the height of the fluidized bed P1. A floating layer P2 may be formed above the fluidized bed P1 in which fine particles such as an object to be roasted, components mixed therein, and roasted products are suspended. The flowing gas flowing from the gas inlet 12 causes an ascending flow over the entire cross section of the furnace body 11 through the gas dispersion plate 14 having a large number of holes to float the object to be roasted.

As a sulfur source (sulfur source), solid sulfur (elementary sulfur, S) that is solid at room temperature, sulfur oxides (SO _2, etc.), sulfuric acid (H ₂ SO ₄ ), sulfate, sulfide, Examples thereof include sulfide ores such as pyrite (FeS ₂ ). For example, the reaction formula of Ni ₃ S ₂ (solid) in the raw material and the external sulfur content (S) and oxygen (O ₂ ) is as follows.

S (solid) + O ₂ (gas) → SO ₂ (gas)
Ni ₃ S ₂ (solid)+5O ₂ (gas)+SO ₂ (gas)→3NiSO ₄ (solid)
Ni (solid)+SO ₂ (gas)+O ₂ (gas)→NiSO ₄ (solid)

For example, in order to convert the nickel content of Ni ₃ S ₂ into nickel sulfate, the sulfur content of 1/3 mol is insufficient with respect to 1 mol of nickel. Further, in order to convert metallic Ni into nickel sulfate, 1 mol of sulfur is insufficient with respect to 1 mol of nickel. If the supply of sulfur is insufficient, there is a problem that the nickel content is discharged as a roasting product without being converted into nickel sulfate. As described above, when the sulfur content in the raw material is insufficient as the sulfur content necessary to obtain nickel sulfate (NiSO ₄ ) as a roasting product, the sulfur content needs to be supplied to the sulfation roasting step. ..

When sulfuric acid is used as the sulfur source, the roasting furnace 10 and the auxiliary equipment must have durability against sulfuric acid corrosion. Generally, a tantalum material is required as a material having both heat resistance and acid resistance, which is expensive. Further, when the sulfur source is oxidized to an oxidation number of +VI like sulfuric acid or sulfate, in order to suppress the iron content from becoming iron sulfate, setting of reaction conditions in the sulfation roasting step as described later is performed. Is not easy.
As the sulfur source other than the solid sulfur (S), a sulfur content contained in the nickel-containing raw material, or a solid sulfur source having a low oxidation number of the sulfur content such as sulfide or sulfide ore may be used together. If the temperature at which is decomposed into sulfur oxides is too high, it is not easy to set reaction conditions in the sulfation roasting step.
In addition, when the raw material contains a sulfur content such as Ni ₃ S ₂ , the sulfur content in the raw material is oxidized during the roasting to generate SO ₂ gas, which may result in cracking of the particles. Particles during roasting are less likely to coagulate with each other when nickel sulfate is formed on the surface to form a coating layer, but when the particles break and the raw material is exposed, fragmented particles coagulate and coarse particles are formed. If formed, the reactivity may be reduced. Therefore, it is preferable to employ a sulfur source that can shorten the time until it reacts with the raw material to produce nickel sulfate.
Therefore, as the sulfur source, in addition to the sulfur content contained in the raw material, a sulfur source that is easily decomposed to the same level or higher than the raw material is preferable. Therefore, it is preferable that at least a part of the sulfur source is solid sulfur (S). Then, the solid sulfur (S) may be supplied to the roasting furnace 10 after being changed into powder, liquid, or gas. In this case, it is possible to generate a sulfur oxide gas such as SO ₂ in the roasting furnace 10 in an oxygen enriched state. Since sulfur oxides are diffused in the furnace in a gas state, the solid sulfur (S), which is easily burned at high temperature, can be used as a sulfur source to shorten the time required to react with the raw materials. ..

Solid sulfur may be mixed with the object to be roasted, and the object to be roasted may be supplied to the roasting furnace 10 in the form of powder or slurry, but due to the difference in particle size between the two, nickel content and sulfur content may be different. There may be unevenness in the ratio. It is also possible to pelletize so that the ratio of nickel content and sulfur content is constant, but it is a huge man-hour to measure the nickel content and sulfur content before pelletizing and adjust the addition amount of sulfur. Requires. When the composition of the raw material is not always constant, real-time control is required to supply the sulfur content according to the nickel content.

Therefore, it is preferable to be able to control the amount of sulfur supply. Therefore, the roasting furnace 10 of the present embodiment has the sulfur combustion burner 21 on the side portion of the furnace body 11. By installing the sulfur combustion burner 21 in the roasting furnace 10, it is possible to supply sulfur to the sulfur combustion burner 21 and burn it, thereby generating sulfur oxides in the roasting furnace 10. This facilitates control of the conditions for sulfation roasting. The roasting furnace 10 may have a burner that burns an auxiliary fuel such as liquefied natural gas (LNG) as the auxiliary burner 17 other than the sulfur combustion burner 21. As the auxiliary fuel, for example, hydrocarbons can be cited as a component whose components generated by combustion do not affect the sulfation roasting. According to the present embodiment, it is not necessary to use liquid sulfuric acid as the sulfur source, the acid resistance level of the equipment is lower than the sulfuric acid corrosion resistance, and the treatment is easy during operation.

When the raw material is the fluidized bed P1 in the roasting furnace 10, the sulfur combustion burner 21 is preferably installed at a position where the roasted product is taken out from the roasting furnace 10, that is, above the outlet 16. This makes it difficult for the fluidized bed P1 and the flow of the combustion gas from the sulfur combustion burner 21 to interfere with each other. Furthermore, it is preferable to install the sulfur combustion burner 21 at a position where the raw material is supplied to the roasting furnace 10, that is, below the supply port 15. This makes it easier for the sulfur oxides contained in the combustion gas from the sulfur combustion burner 21 to come into contact with the raw material, so that the reaction can be promoted. Further, even when the particle surface of the raw material is metallic and aggregation between particles is likely to occur, the reaction on the particle surface is promoted, whereby the aggregation can be suppressed.

In this embodiment, the sulfur combustion burner 21 is provided with the sulfur supply system 20. The sulfur supply system 20 includes a sulfur melting tank 22 that melts solid sulfur into a liquid state, and a sulfur supply passage 26 that supplies liquid sulfur from the sulfur melting tank 22 to the sulfur combustion burner 21. The sulfur supply system 20 includes a heater 23 for heating the sulfur melting tank 22. Liquid sulfur can obtain fluidity even in a solution or dispersion of sulfur such as hydrocarbon, but it is preferably prepared by melting solid sulfur because it has a wide stable temperature range as a liquid. Since liquid sulfur is passed through the sulfur supply passage 26, it is preferable to maintain the temperature higher than the melting point of sulfur (about 115° C.) and lower than the boiling point of sulfur (about 444° C.).

The sulfur supply passage 26 preferably has a pump 24 for supplying liquid sulfur to the sulfur combustion burner 21. This facilitates the transportation of sulfur and facilitates the control of combustion in the sulfur combustion burner 21. Further, it is preferable that the sulfur supply passage 26 includes a valve 25 capable of adjusting the flow rate of the liquid sulfur stepwise or continuously. As a result, the flow rate of sulfur can be easily controlled, and the amount of sulfur oxide generated in the sulfur combustion burner 21 can be controlled with higher accuracy.

An auxiliary combustion gas supply passage 27 is connected to the sulfur combustion burner 21 in order to supply an auxiliary combustion gas containing oxygen for burning sulfur. Air is generally used as the combustion supporting gas. It is preferable to remove dust from the air with a filter or the like. Furthermore, moisture may be removed to obtain dry air. It is also possible to add oxygen or nitrogen to the air to appropriately change the concentration of the oxygen gas (O ₂ ). The auxiliary combustion gas supply passage 27 preferably includes a valve 28 capable of adjusting the flow rate of the auxiliary combustion gas stepwise or continuously. This facilitates the control of the flow rate of the auxiliary combustion gas, and the amount of sulfur oxide generated in the sulfur combustion burner 21 can be controlled with higher accuracy.

In the case of the present embodiment, in order to control the concentration of sulfur oxide in the roasting furnace 10 with higher accuracy, the roasting furnace 10 can be provided with a sulfur oxide concentration control system 30. For example, the densitometer 32 is installed in the furnace body 11 to measure the sulfur oxide concentration in the roasting furnace 10. The controller 31 controls the amount of sulfur or air supplied to the sulfur combustion burner 21 based on the measured value of the sulfur oxide concentration in the roasting furnace 10 transmitted from the concentration meter 32 via the signal line 34. This makes it possible to easily control excess and deficiency of sulfur oxides in the roasting furnace 10. For example, when the measured value of the sulfur oxide concentration in the roasting furnace 10 is low, the supply amount of sulfur or oxygen is increased, and when the measured value of the sulfur oxide concentration in the roasting furnace 10 is high, sulfur or Reduce the supply of oxygen. Whether to change the supply amount of sulfur or the supply amount of oxygen may be determined differently depending on the situation.

Further, the concentration meter 33 is installed at the gas outlet 13 for measuring the sulfur oxide concentration in the exhaust gas discharged from the roasting furnace 10. The controller 31 controls the amount of sulfur or air supplied to the sulfur combustion burner 21 based on the measured value of the sulfur oxide concentration in the exhaust gas transmitted from the concentration meter 33 via the signal line 35. As a result, the sulfur oxide concentration in the roasting furnace 10 can be controlled in consideration of the amount of sulfur oxide flowing out into the exhaust gas. For example, when the sulfur oxide concentration in the exhaust gas is high and it is determined that the sulfur oxide concentration in the roasting furnace 10 is excessive, the sulfur oxide concentration in the roasting furnace 10 may be controlled to decrease. ..

In the case of the present embodiment, the controller 31 determines the opening degrees of the

valves

25 and 28 based on the signals from the

densitometers

32 and 33. Specifically, when controlling the supply amount of sulfur, the controller 31 opens and closes the valve 25 via the signal line 36. In addition, the controller 31 opens and closes the valve 28 via the signal line 37 when controlling the supply amount of the auxiliary combustion gas.

2 is a cross-sectional view taken along a plane perpendicular to the centerline C extending in the vertical direction of the furnace body 11 shown in FIG. Note that FIG. 2 is a simplified conceptual diagram, and does not necessarily show an optimum state or value with respect to the relationship such as shape, position, size, angle, and ratio. As shown in the cross-sectional view of FIG. 2, the sulfur combustion burner 21 is installed along the wall surface of the furnace body 11 of the roasting furnace 10, and intersects in the direction along the inner wall surface 10A of the roasting furnace 10 and in the vertical direction. It is preferable to supply sulfur in the direction in which it does. As a result, the swirling flow F in which the combustion gas from the sulfur combustion burner 21 flows in the roasting furnace 10 along the inner wall surface 10A of the roasting furnace 10 (furnace body 11) with the substantially vertical direction as the central axis (Fig. (See also 1), the sulfur oxide contained in the combustion gas is easily diffused in the entire furnace body 11. As a result, the sulfur oxide can be easily reacted with the raw material without impeding the flow of the raw material in the floating layer P2 formed above the fluidized bed P1. In this case, the combustion gas from the sulfur combustion burner 21 may rise along with the upward flow of the flow gas and generate a spiral swirling flow F. The swirling flow F may be diffused from the vicinity of the inner wall surface 10A to the vicinity of the center line C.

The furnace body 11 of this embodiment is formed in a cylindrical shape. The wall thickness between the inner wall surface 10A and the outer wall surface 10B may be uniform or non-uniform. The inner wall surface 10A and the outer wall surface 10B may be both surfaces of the same wall material, or may be inner surfaces and outer surfaces of different wall materials. Each of the inner wall surface 10A and the outer wall surface 10B may be a flat cylindrical surface, or may have minute surface undulations or the like. The wall structure may be a multi-layer structure in which the inner surface of the structural material is lined. An acid resistant lining material or the like may be used as the inner wall material of the furnace body 11, but the lining material or the like may be omitted. At least the tip of the sulfur combustion burner 21 may protrude from the inner wall surface 10A. The sulfur combustion burner 21 itself may penetrate the outer wall surface 10B on the rear end side (the side connected to the sulfur supply passage 26) opposite to the tip end of the sulfur combustion burner 21, or the sulfur combustion burner 21 may be a wall surface. The outer wall surface 10B may be passed through the sulfur supply passage 26 on the rear side thereof. The direction of the sulfur combustion burner 21 with respect to the wall surface of the furnace body 11 is, for example, about 5 to 45° in angle R with respect to the tangent line of the wall surface in the horizontal section. Specifically, the sulfur combustion burner 21 includes a main body portion 21A connected to the sulfur supply passage 26, and a crater 21B for injecting combustion gas into the roasting furnace 10. The crater 21B is provided at the tip of the main body 21A. In the present embodiment, the sulfur combustion burner 21 is installed so that the body portion 21A has an angle R of 5 to 45° with respect to the tangent line T of the wall surface of the furnace body 11. Here, as an example of the tangent line T, the tangent line of the inner wall surface 10A at the installation position of the main body portion 21A is shown in the cross section of FIG. 2, but the angle R may be an angle with the tangent line of the outer wall surface 10B. In FIG. 2, the sulfur supply passage 26 is extended on the extension line of the main body portion 21A of the sulfur combustion burner 21, but the sulfur supply passage 26 is not particularly limited to this, and inside the wall surface of the furnace body 11 or on the outer wall surface 10B. The sulfur supply passage 26 may be bent along or further outside. Depending on the length of the sulfur combustion burner 21, it may be possible to connect the sulfur supply passage 26 in the middle of the main body portion 21A, but in that case as well, the angle R is closer to the crater 21B than the connection portion with the sulfur supply passage 26. It is set between the tangent line T and the side. The angle R may be the angle between the tangent line T and the central axis line that is perpendicular to the surface of the crater 21B. When the swirl flow F is generated closer to the inner wall surface 10A of the furnace body 11, the main body portion 21A is installed so as to be about 5 to 30° with respect to the tangent line T of the wall surface of the furnace body 11. Is preferred. Examples of the value of the angle R include 5°, 10°, 15°, 20°, 25°, 30°, or values in the vicinity or in the middle thereof. Further, the main body portion 21A of the sulfur combustion burner 21 with respect to the vertical direction may be a horizontal direction, or may be upward or downward from the horizontal direction, but when tilted from the horizontal direction, for example, within 5° or 10° upward or downward. It is preferably within. When a fluidized roasting furnace is used as the roasting oven 10, it may be adjusted according to the flow velocity of the fluidizing gas so as to resist the upward flow of the fluidizing gas.

In the sulfation roasting of a nickel-containing raw material, the oxygen partial pressure and the sulfur dioxide partial pressure are such that nickel sulfate is more thermodynamically stable than nickel oxide in the Ni—S—O system and the Fe—S—O system is used. In the above, it is preferable that the iron oxide is thermodynamically more stable than iron sulfate. As a result, even when the nickel-containing raw material contains iron, the nickel is converted to nickel sulfate and the conversion of iron to iron sulfate is suppressed, so that the consumption of sulfur by iron is suppressed. The production efficiency of nickel sulfate can be improved.

FIG. 3 is an example of a conceptual state diagram of the Ni—S—O system and the Fe—S—O system. The boundary line of each phase in the Ni-S-O system is shown by a broken line (---), and the boundary line of each phase in the Fe-S-O system is shown by a one-dot chain line (-.-.-). .. The chemical formulas attached to the arrows indicate thermodynamically stable phases on the side from each boundary toward the arrow. The horizontal axis in the state diagram shown in FIG. 3 shows the logarithm of the partial pressure of O _2, the right side as the O ₂ partial pressure is high, the left as O ₂ partial pressure is low. The vertical axis in the state diagram shown in FIG. 3 shows the logarithm of the SO ₂ partial pressure, the upper as SO ₂ partial pressure is high, the lower the lower SO ₂ partial pressure. The unit of partial pressure is, for example, atmospheric pressure (atm=101325 Pa).

Examples of nickel sulfate contained in the Ni—S—O system include NiSO ₄ , and examples of nickel oxide include NiO. In the state diagram shown in FIG. 3, a boundary line L _Ni indicates a boundary line between a region where nickel sulfate is thermodynamically stable and a region where nickel oxide is thermodynamically stable. In the region where the SO ₂ partial pressure and the O ₂ partial pressure are higher than the boundary line L _Ni , nickel sulfate is a thermodynamically stable phase. Further, in the region where the SO ₂ partial pressure and the O ₂ partial pressure are lower than the boundary line L _Ni , nickel oxide becomes a thermodynamically stable phase.

Examples of the iron sulfate contained in the Fe—S—O system include FeSO ₄ and Fe ₂ (SO ₄ ) ₃ , and examples of the iron oxide include Fe ₂ O ₃ . In the state diagram shown in FIG. 3, a boundary line L _Fe indicates a boundary line between a region where iron sulfate is thermodynamically stable and a region where iron oxide is thermodynamically stable. In the region where the SO ₂ partial pressure and the O ₂ partial pressure are higher than the boundary line L _Fe , iron sulfate is a thermodynamically stable phase. Further, in a region where the SO ₂ partial pressure and the O ₂ partial pressure are lower than the boundary line L _Fe , iron oxide becomes a thermodynamically stable phase.

According to the state diagram shown in FIG. 3, SO ₂ partial pressure and the partial pressure of _{O 2} is lower than the boundary line _{L Fe,} and, SO ₂ partial pressure and the partial pressure of _{O 2} is in the higher region A than the boundary line _{L Ni,} Ni In the —SO system, nickel sulfate is a thermodynamically stable phase, and in the Fe—S—O system, iron oxide is a thermodynamically stable phase. Therefore, under the conditions of the overlapping region A, by roasting a system containing nickel (Ni), oxygen (O), and sulfur (S), iron sulfate is produced even if iron is present in the system. The nickel content can be converted to nickel sulfate while suppressing.

The roasting temperature (sulfate roasting temperature) in the sulfation roasting step of the present embodiment is preferably in the range of 400 to 750°C, more preferably in the range of 550 to 750°C. Specific examples of the sulfation roasting temperature include 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., or a temperature range before, after, or in the middle thereof. With such a roasting temperature, reduction of iron content is suppressed, and iron content can coexist with a nickel sulfate compound in a state of iron oxide, iron sulfide, etc., thus suppressing aggregation of particles in a roasted product, It is possible to facilitate the processing in the subsequent steps. Further, at these temperatures, the carbonate decomposes, so even if the carbonate is mixed, it is possible to prevent the carbonate from being dissolved in water and remaining as an impurity. Can be easily processed.
Further, the sulfation roasting temperature is preferably 600 to 700°C. At this temperature, even if the object to be roasted contains manganese (Mn) as an impurity derived from the nickel-containing raw material, manganese forms a spinel structure with iron to remove manganese as an insoluble material. Easier to do.

As the O ₂ partial pressure in the sulfation roasting step, the common logarithm of the O ₂ partial pressure in terms of atmospheric pressure (atm) log p(O ₂ ) is preferably in the range of −4 to −6, and depending on the conditions etc., log p _{(O 2)} is -4 to -5, or log p _{(O 2)} is more preferably in the range of -5 to -6. By decreasing the O ₂ partial pressure, the SO ₂ partial pressure tends to increase even in the overlapping region A of FIG. 3, so that the generation of nickel sulfate can be promoted while suppressing the generation of iron sulfate. The optimum region is slightly shifted depending on the sulfation roasting temperature, and the higher the temperature, the more the log p(O ₂ ) in the overlapping region A increases (the closer to zero (0)). Depending on the relationship between log p(SO ₂ ) and the sulfation roasting temperature, log p(O ₂ ) may be selected from the range of −8 to 0, for example.

The SO ₂ partial pressure in the sulfation roasting step, pressure (atm) preferably common logarithm log p (SO ₂₎ range is -1 to + 1 SO ₂ partial pressure in units, log p (SO ₂₎ is - The range of 1 to 0 is more preferable. In the overlapping region A of FIG. 3, the SO ₂ partial pressure can be made higher to promote the production of sulfate. Furthermore, by setting the SO ₂ partial pressure to about normal pressure or less (the common logarithm of partial pressure is approximately 0 or less), the total pressure of the roasting atmosphere in the sulfation roasting step does not become excessive, The equipment can be easily handled. The log p(SO ₂ ) may be selected from the range of −4 or more and +1 or less depending on the relationship with the log p(O ₂ ) and the sulfation roasting temperature.

In order to maintain the condition of low O ₂ partial pressure in the roasting furnace, an inert gas such as nitrogen (N ₂ ) or argon (Ar) may be supplied to the roasting furnace. These inert gases can also be used as a carrier when supplying volatile components such as gas and steam to the roasting furnace. The SO ₂ partial pressure can be adjusted by controlling the supply amount of the sulfur source as described above.
The preferable partial pressure range can be determined from the positions of the boundary line L _Ni and the boundary line L _Fe by examining the above-mentioned phase diagram according to the sulfation roasting temperature. For example, when the sulfation roasting temperature is 650 to 750° C., the preferable partial pressure range is as follows: log p(O ₂ ) is about −8 to −4, log p(SO ₂ ) is about −2 to +2, log p(O ₂ ) is about -3 to -2, log p(SO ₂ ) is about -3 to +1 and log p(O ₂ ) is about -1 to 0, log p(SO ₂ ) is -4 to 0 is mentioned.

The roasting product containing nickel sulfate compound is obtained by the sulfation roasting process. A solution containing a nickel sulfate compound is obtained by a water dissolving step of supplying water to the roasted product and dissolving the nickel sulfate compound in water. As described above, the iron content contained in the roasted product of the sulfation roasting process is insoluble in water such as iron oxide and iron sulfide, so it is separated into a solid phase and a liquid phase by solid-liquid separation. By doing so, a nickel sulfate compound is obtained as a liquid phase, and impurities containing iron and the like are separated as a solid phase. Further, if necessary, a nickel sulfate compound from which impurities such as cobalt have been removed can be obtained by performing a purification step in order to separate nickel sulfate from cobalt sulfate or the like.

The water added to the roasted product in the water dissolution step is preferably pure water that has been treated so as not to contain impurities. The water treatment method is not particularly limited and may be one or more of filtration, membrane separation, ion exchange, distillation, disinfection, chemical treatment, adsorption and the like. As the water for dissolution, tap water obtained from a water source, industrial water, or the like may be used, or water obtained by treating wastewater generated in another process may be used. You may use 2 or more types of water. Not only pure water but also a sulfuric acid acidic solution having a pH of about 4 can be used for dissolution. For example, in a region where the pH of the solution is about 4 to 5, for example, 3.8 to 5.5, which is an oxidation region in the redox potential measurement, nickel sulfate compound is suppressed while suppressing dissolution of other impurities such as sulfates. Is preferred because it is advantageous to selectively extract the broth in the aqueous phase.

The solubility of nickel sulfate in water is highest at 150° C., 55 g of NiSO ₄ dissolves in 100 g of solution, but 22 g of NiSO ₄ dissolves in 100 g of solution even at 0° C. Therefore, it is desirable to carry out the dissolving operation at a temperature not higher than the boiling point of water. Further, the solution obtained in the water dissolution step preferably has a concentration at which NiSO ₄ does not precipitate even at room temperature, and a solution having a higher concentration of NiSO ₄ is preferably kept warm.

The solid-liquid separation method after the water dissolution step is not particularly limited, and examples thereof include a filtration method, a centrifugation method, and a sedimentation method. Desirably, it is preferable to use an apparatus having high separation performance for media and fine particles contained in the solid phase. For example, in the filtration method, the filtration method is not particularly limited, and examples thereof include gravity filtration, reduced pressure filtration, pressure filtration, centrifugal filtration, filter aid addition type filtration, squeezing filtration and the like. Pressure filtration is preferable because the differential pressure can be easily adjusted and rapid separation is possible.

Examples of impurities that can coexist with the nickel sulfate compound include iron (Fe), cobalt (Co), and aluminum (Al). When these metal salts are sulfates in the roasting step, when the nickel sulfate compound is dissolved in water, iron sulfate, cobalt sulfate, etc. are also dissolved. Further, in water, for example, iron precipitates as oxides such as FeOOH, Fe ₂ O ₃ , Fe ₃ O _{4 and the} like, which facilitates removal of impurities from the nickel sulfate compound. In the sulfated roasting step of the present embodiment, the conditions in which the iron content is unlikely to become iron sulfate are set, and therefore, a nickel sulfate compound having a low iron content can be obtained through water dissolution and solid-liquid separation. The residue containing iron oxide or the like after dissolving the nickel sulfate compound can be reused as the iron content of cement. Further, the iron-rich residue such as iron oxide can be used for producing pig iron or the like as an iron-making raw material using a smelting reduction furnace, an electric furnace, etc., or for pigments, ferrites, magnetic materials, sintered materials, etc. .. Especially when the area producing nickel-containing raw materials is an industrial area or a remote place away from cities, it is advantageous from the viewpoint of transportation cost to commercialize iron as well as nickel. is there. For example, if pig iron is produced using an electric furnace provided in the ferronickel smelting process and the volume of the pig iron is reduced, it can be easily carried out as iron ingot.

Among impurities, for example, metals having a lower ionization tendency than hydrogen (H) such as copper (Cu), gold (Au), silver (Ag), and platinum group metal (PGM) remain as solids in the water dissolution step, and thus solid It can be removed by a liquid separation step. The solids removed by the solid-liquid separation step may include compounds such as As, Pb, and Zn in addition to the above impurities. The solid containing these impurities can also be recycled as a valuable resource.

Since the solution obtained through water dissolution and solid-liquid separation has a nickel sulfate compound as a main component, it can be transported and used as a solution of the nickel sulfate compound or as a solid of the nickel sulfate compound by drying or the like. .. Depending on the application, if it is desired to reduce impurities such as cobalt sulfate in the solution, solvent extraction, electrolytic dialysis (Electrodialysis), electrowinning, electrolytic refining, ion exchange, Techniques such as crystallization can be used.

In the case of solvent extraction, it is preferable to use an extractant that can preferentially or selectively extract cobalt over nickel over the solvent. This allows the nickel sulfate compound to remain in the aqueous solution for efficient purification. Examples of the extractant include organic compounds having a functional group capable of binding to a metal ion, such as a phosphinic acid group and a thiophosphinic acid group. In the solvent extraction, an organic solvent capable of separating the extractant from water may be used as the diluent. Dissolving the extractant combined with a metal ion such as cobalt in the diluent facilitates separation from the aqueous solution containing the nickel sulfate compound without using a large amount of the extractant. The diluent is preferably an organic solvent that is difficult to mix with water.

In the case of crystallization, the target nickel sulfate compound may be crystallized from the solution by at least one factor such as temperature change, solvent reduction, addition of another substance, and the like. At this time, purification can be performed by leaving at least a part of the impurities in the liquid phase. Specific examples include an evaporation crystallization method and a poor solvent crystallization method. In the evaporative crystallization method, the solution is concentrated by boiling or evaporation under reduced pressure to crystallize the nickel sulfate compound. The poor solvent crystallization method is a crystallization method utilized in the production of pharmaceuticals, for example, a solution containing a nickel sulfate compound is added with an organic solvent to precipitate a nickel sulfate compound. The organic solvent used for crystallization is preferably an organic solvent miscible with water, and examples thereof include one or more selected from the group consisting of methanol, ethanol, propanol, isopropanol, butyl alcohol, ethylene glycol, and acetone. Two or more kinds of organic solvents may be used. Regarding the concentration range in which the organic solvent is miscible with water, it is preferred that the organic solvent is miscible at a concentration at which the nickel sulfate compound is precipitated, and it is more preferred that the organic solvent is freely mixed at an arbitrary ratio. The organic solvent added in the crystallization step is not limited to an anhydrous organic solvent, and may be a water-containing organic solvent as long as it does not hinder crystallization. The ratio of water to the organic solvent is not particularly limited and may be set, for example, in the range of 1:20 to 20:1, but is preferably about 1:1 and is preferably 1:2 to 2:1.

When a solid nickel sulfate compound is obtained through crystallization, etc., it is in the state of anhydrous nickel sulfate, monohydrate, dihydrate, pentahydrate, hexahydrate, heptahydrate, etc. May be. The nickel sulfate compound deposited by crystallization can be separated from the solution by solid-liquid separation. The solid-liquid separation method is not particularly limited, and examples thereof include a filtration method, a centrifugation method, and a sedimentation method. The metal dissolved on the solution side is preferably removed from the solution by a method such as neutralization and precipitation. When the purified solution is mainly composed of a mixture of water and an organic solvent, the water and the organic solvent can be separated by a method such as distillation.

According to the sulfated roasting of this embodiment, the following effects can be obtained.
(1) Even when a raw material having a non-uniform composition is roasted, the SO ₂ partial pressure can be immediately controlled according to the reaction state in the roasting furnace. In addition, since the SO ₂ partial pressure can be controlled immediately, it is easy to control the reaction conditions when performing the sulfated roasting in the overlapping region A described above.
(2) The conversion reaction from the nickel-containing raw material to nickel sulfate can be accelerated, and the reactivity is improved.
(3) A high-purity nickel sulfate compound can be produced from a nickel-containing raw material by sulfation and roasting.
(4) Generation of iron sulfate can be suppressed in the sulfation roasting process. Further, generation of hydrogen (H ₂ ) gas can also be suppressed.
(5) In the roasted product, the iron content becomes a chemical species that is difficult to dissolve in water, and the nickel content easily dissolves in water as a nickel sulfate compound, so that the iron content is easily removed.
(6) The equipment cost can be reduced as compared with the conventional method.
(7) Since the conversion reaction of the nickel-containing raw material can be promoted, for example, when iron is supplied in the state of iron oxide, iron oxide forms an opportunity to form iron sulfate and forms an iron-nickel ferrite alloy. The conversion reaction proceeds without giving the opportunity to do so. Therefore, a roasting product containing high-purity nickel sulfate can be obtained.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

The object to be roasted is not limited to a nickel-containing raw material, and a raw material containing a metal other than nickel (Cu, Zn, Co, Fe, etc.) may be considered. It is also possible to apply roasting of the nickel-containing raw material according to the above-described embodiment to roasting for obtaining a compound of the metal from a raw material containing another metal.

An electric furnace manufactured by Takasago Industry (core tube: SUS316L, outer diameter 50 mm, length 400 mm, maximum temperature 1100°C) was installed so that the core tube was vertical, and a gas dispersion plate was installed under the core tube. And constituted a fluidized roasting furnace. The material to be roasted as the raw material supplied into the fluidized roasting furnace is a nickel matte (composition: Ni ₃ S ₂ , average particle diameter: 0.3 mm, density: 3.5 g/cm ³ , Mohs hardness: 4 to 5). ) Was 1000 g. A gas absorption tube and a vacuum pump were installed above the fluidized-bed roasting furnace.

Regarding the method of supplying the sulfur source, the following five methods were used.
(No. 1) A sulfur source is not added and only the sulfur content contained in the nickel matte is used.
(No. 2) Sulfur content is mixed and supplied to the nickel mat as solid sulfur powder.
(No. 3) Sulfur content is mixed as solid sulfur with nickel matte, and pelletized in advance and supplied.
(No. 4) Sulfur content is sprayed as a sulfuric acid solution as a liquid from the upper part of the core tube.
(No. 5) A sulfur combustion burner is inserted from the side of the core tube, the direction of the sulfur combustion burner is adjusted so that the combustion gas becomes a spiral flow, and sulfur is burned by the sulfur combustion burner.

No. 1, No. 2, No. 4, No. In No. 5, after the nickel matte was supplied into the core tube of the fluidized roasting furnace, the air for fluidization was supplied from the lower part of the fluidized roasting furnace to maintain the fluidized bed of the nickel matte. No. In No. 3, in order to make the conditions as uniform as possible, the air for fluidization was supplied from the lower part of the fluidized roasting furnace, but since the nickel mat was also in pellet form, the fluidized bed was not formed.

The atmosphere of the sulfated roasting conditions was a roasting temperature of 700° C. and a log p(O ₂ ) of −2. No. 2 and No. In 3, the amount of 1.2 times the theoretically required number of moles of the sulfur component with respect to the nickel component was used as a guide, and then the insufficient amount of solid sulfur was added in advance. No. 4 and No. In 5, the addition amount of the sulfur source was controlled in real time so that log p(SO ₂ ) was −2. When the sulfur content burned in the roasting furnace, the output of the electric furnace was adjusted according to the combustion energy to maintain the temperature of 700°C. The time when the temperature in the roasting furnace reached 700° C. was set as the start time, and then the sulfated roasting was continued for up to 30 minutes, and the SO ₂ partial pressure in the roasting furnace was measured.

Table 1 shows the common logarithm of the SO ₂ partial pressure in terms of atmospheric pressure (atm) log p(SO ₂ ) as the measurement results of the SO ₂ concentration at the elapsed times of 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 30 minutes. Indicates the value of. No. 1, No. 2 and No. In No. 3, the SO ₂ partial pressure was not constant while the roasting was continued at 700° C. for 30 minutes from the start of roasting. No. In No. 4, the core tube was corroded 30 minutes after the start of roasting, and roasting at 700° C. for 30 minutes could not be continued. No. In No. 5, log p(SO ₂ ) could be kept constant at −2.0 while the roasting was continued at 700° C. for 30 minutes from the start of roasting. From the preliminary examination of the phase diagrams of Ni—S—O system and Fe—S—O system, log p(O ₂ ) is −2.0 and log p(SO ₂ ) is −2.0 at the roasting temperature of 700° C. The condition of 2.0 is considered suitable for conversion to NiSO ₄ .

Further, the roasted product was dissolved in pure water, and the Ni recovery rate was measured as the rate at which the nickel content was recovered as NiSO ₄ . The Ni recovery rate is the ratio of the Ni content (the quantity corresponding to Ni in NiSO ₄ ) dissolved in pure water, with the Ni content contained in the sample used for the sulfation roasting being 100 wt %.
The Ni recovery rate is No. 18% for No. 1, No. 1 65% in No. 2, No. 75% in No. 3, No. 3 80% in No. 4, No. 4 5 was 91%. No. corresponding to the embodiment of the present invention. In the case of 5, the Ni recovery rate was the highest.

From this result, it can be seen that the No. In No. 1, it is considered that the SO ₂ partial pressure rises while the roasting is continued because the sulfur content in the nickel matte did not sufficiently react with the nickel content and diffused into the atmosphere. No. 1 in which sulfur was added in advance so that the sulfur content became excessive. 2 and No. In Example 3, the initial SO ₂ partial pressure was low, and while the roasting was continued, the oxidation of sulfur proceeded to gradually increase the SO ₂ partial pressure, but the Ni recovery rate was not so high. This is considered to be because the situation where the SO ₂ partial pressure is low in spite of the high O ₂ partial pressure in the initial stage had an adverse effect on the conversion to NiSO ₄ . No. ₂ whose SO ₂ partial pressure was controlled using a sulfuric acid solution. In No. ₄ , although the partial pressure of SO ₂ suitable for conversion to NiSO ₄ was maintained, the situation was such that the roasting was stopped midway, so it is considered that the Ni recovery rate did not become so high. No. 1 in which SO ₂ partial pressure was controlled by burning sulfur with a burner. In No. 5, it was considered that the Ni recovery rate was high because the SO ₂ partial pressure suitable for conversion to NiSO ₄ could be maintained.

The present invention can be used for producing high-purity nickel sulfate compounds useful as raw materials for various nickel compounds or metallic nickel used in electric parts such as secondary batteries and chemical products.

10... Roasting furnace, 10A... Inner wall surface, 11... Furnace body, 12... Gas inlet, 13... Gas outlet, 14... Gas dispersion plate, 15... Supply port, 16... Outlet, 17... Auxiliary burner, 20... Sulfur Supply system, 21... Sulfur combustion burner, 21A... Main body part, 21B... Crater, 22... Sulfur melting tank, 23... Heater, 24... Pump, 25... Sulfur supply passage valve, 26... Sulfur supply passage, 27... Combustion gas Supply path, 28... Valve of auxiliary combustion gas supply path, 30... Control system, 31... Controller, 32, 33... Densitometer, 34, 35, 36, 37... Signal line.

Claims

In the step of performing sulfation roasting of a raw material containing nickel and iron, a burner is installed in a roasting furnace, sulfur is supplied to the burner and burned, and a sulfur oxide is generated in the roasting furnace. Characterized sulfate roasting method.
The sulfurization and roasting method according to claim 1, wherein the sulfur is supplied in liquid form to the burner by air pressure.
The sulfation according to claim 1 or 2, wherein the concentration of sulfur oxide in the roasting furnace is measured, and the amount of sulfur or air supplied to the burner is controlled based on the measured value. Roasting method.
The concentration of sulfur oxide in the exhaust gas discharged from the roasting furnace is measured, and the amount of sulfur or air supplied to the burner is controlled based on the measured value. The sulfated roasting method according to any one of items.
5. The burner is installed in the roasting furnace as a fluidized bed, and the burner is installed above a position where a roasted product is taken out from the roasting furnace. Sulfate roasting method.
The burner is installed along the wall surface of the roasting furnace, and sulfur is supplied in a direction along the inner wall surface of the roasting furnace and in a direction intersecting the vertical direction. The sulfated roasting method described.
The sulfation roasting method according to claim 5 or 6, wherein the burner is installed below a position where the raw material is supplied to the roasting furnace.
Regarding oxygen partial pressure and sulfur dioxide partial pressure, nickel sulfate is thermodynamically more stable than nickel oxide in the Ni—S—O system, and iron oxide is more thermodynamic than that in the Fe—S—O system than iron sulfate. 8. The sulfated roasting method according to any one of claims 1 to 7, wherein the conditions are such that it becomes stable.