WO2020174573A1

WO2020174573A1 - Residue processing method and sulfatizing roasting method

Info

Publication number: WO2020174573A1
Application number: PCT/JP2019/007272
Authority: WO
Inventors: 賢三左右田
Original assignee: 日揮グローバル株式会社
Priority date: 2019-02-26
Filing date: 2019-02-26
Publication date: 2020-09-03
Also published as: JPWO2020174573A1; PH12021550518A1; AU2019431265A1

Abstract

This residue processing method is characterized by the application of a centrifugal force on a residue containing a nickel fraction and iron oxide to separate the nickel fraction from the iron oxide.

Description

Residue treatment method and sulfated roasting method

The present invention relates to a residue treatment method and 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 residue treatment method capable of efficiently treating a residue containing nickel and iron oxide, and a sulfation roasting method using the same.

A first aspect of the present invention is a residue treatment method, characterized in that a residue containing nickel and iron oxide is subjected to centrifugal force to separate the nickel and iron oxide.

A second aspect of the present invention is the residue treatment method according to the first aspect, characterized in that the average particle size of nickel and the average particle size of iron oxide are different.

A third aspect of the present invention is the residue treatment method according to the first or second aspect, characterized in that the average particle size of nickel is larger than the average particle size of iron oxide.

A fourth aspect of the present invention is the residue treatment method according to the first to third aspects, characterized in that the average particle diameter of the residue is within a range of 50 μm to 150 μm.

In a fifth aspect of the present invention, the residue has a partial pressure of oxygen and a partial pressure of sulfur dioxide of which nickel sulfate is more thermodynamically stable than nickel oxide in a Ni—S—O system, and Fe—S— In the O-system, the residue treatment method according to any one of the first to fourth aspects is characterized in that it is a residue obtained from sulfation roasting under the condition that iron oxide is more thermodynamically stable than iron sulfate. ..

A sixth aspect of the present invention is the residue treatment method according to any one of the first to fifth aspects, characterized in that the nickel component obtained by separating iron oxide from the residue is treated in a sulfation roasting furnace.

A seventh aspect of the present invention is the residue treatment method according to the sixth aspect, characterized in that a nickel component obtained by separating iron oxide from the residue is supplied to the sulfation roasting furnace in a slurry state.

An eighth aspect of the present invention is the residue treatment method according to the sixth aspect, characterized in that the nickel component from which iron oxide has been separated from the residue is dried and supplied to the sulfation roasting furnace.

A ninth aspect of the present invention is the residue treatment method according to the eighth aspect, characterized in that the nickel component obtained by separating iron oxide from the residue is dried by exhaust heat of the sulfation roasting furnace.

A tenth aspect of the present invention is that, in the above-mentioned sulfation roasting furnace, the oxygen partial pressure and the sulfur dioxide partial pressure are such that nickel sulfate is thermodynamically more stable than nickel oxide in the Ni—S—O system, and The residue treatment method according to any of the sixth to ninth aspects is characterized in that the Fe—S—O system is under the condition that iron oxide is thermodynamically more stable than iron sulfate.

An eleventh aspect of the present invention is a roasting step of treating a nickel-containing raw material containing iron in a sulfation roasting furnace, and an extraction for extracting a nickel sulfate compound from the roasted product obtained in the roasting step. And a residue treatment step of treating the residue obtained after extracting the nickel sulfate compound in the extraction step by the residue treatment method of the first to tenth aspects to separate nickel content and iron oxide. And a reuse step of supplying the nickel component obtained in the residue treatment step to a sulfation roasting furnace used in the roasting step, which is a sulfation roasting method.

According to the first aspect, since the specific gravity of iron oxide is larger than the specific gravity of nickel component, centrifugal force is applied to the residue containing nickel component and iron oxide, so that the nickel component and iron oxide are efficiently separated. be able to.

According to the second aspect, even when the average particle size of the nickel component and the average particle size of the iron oxide are different, the nickel component and the iron oxide can be efficiently separated by the centrifugal force.

According to the third aspect, even when the average particle size of the nickel component is larger than the average particle size of the iron oxide, the nickel component and the iron oxide can be efficiently separated by the centrifugal force.

According to the fourth aspect, the nickel content and the iron oxide can be efficiently separated even when the average particle size of the residue is in the range of 50 μm to 150 μm.

According to the fifth aspect, in the sulfation roasting, the nickel content of the raw material is converted to nickel sulfate and the conversion of iron content to iron sulfate is suppressed, so that the sulfur content consumption by the iron content is suppressed. The production efficiency of nickel sulfate can be improved.

According to the sixth aspect, the nickel component from which iron oxide has been separated from the residue can be converted to nickel sulfate for effective use.

According to the seventh aspect, by supplying the nickel content in a slurry state to the sulfation roasting furnace, the nickel content can be easily transported and steam can be generated in the sulfation roasting furnace. The efficiency of the sulfur source existing in the sulfation roasting furnace being oxidized to generate the sulfur oxide necessary for the sulfation roasting is improved.

According to the eighth aspect, by drying the nickel content and supplying it to the sulfation roasting furnace, it is possible to reduce the weight of the nickel content during transportation and reduce the loss.

According to the ninth aspect, the energy recovery rate can be improved by drying the nickel component by the exhaust heat of the sulfation roasting furnace.

According to the tenth aspect, since the nickel content of the residue is converted to nickel sulfate and the conversion of iron content to iron sulfate is suppressed, the sulfur content consumption by the iron content is suppressed, and the nickel sulfate production efficiency is reduced. Can be improved. Further, since the nickel content derived from the residue is in the form of fine powder at the residue stage, the conversion reaction is efficient even in the sulfation roasting, and the treatment becomes easy.

According to the eleventh aspect, the nickel component and the iron oxide can be efficiently separated by applying a centrifugal force to the residue after extracting the nickel sulfate compound from the roasted product of the nickel-containing raw material. .. Further, by recycling the recovered nickel content as at least a part of the nickel-containing raw material, the yield of sulfation roasting of the nickel-containing raw material can be improved.

It is a block diagram of the sulfation roasting method using the residue treatment method of embodiment. FIG. 2 is a conceptual state diagram of Ni—S—O system and Fe—S—O system.

In the sulfation roasting method using the residue treatment 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 approximately 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 nickel sulfide ore (Pentland ore), needle 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 means for pulverizing the nickel-containing raw material is not particularly limited, and one or more types of ball mill, rod mill, hammer mill, fluid energy mill, vibration mill and the like can be used. The particle size of the nickel-containing raw material 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.

The sulfated roasting method of the present embodiment is a roasting step in which a nickel-containing raw material containing iron is treated in a sulfated roasting furnace, and a nickel sulfate compound is extracted from the roasted product obtained in this roasting step. And a residue treatment step of treating the residue obtained after extracting the nickel sulfate compound in this extraction step by the residue treatment method of the present embodiment to separate nickel content and iron oxide, and this residue treatment And a reuse step of supplying the nickel component obtained in the step to a sulfation roasting furnace used in the roasting step.

FIG. 1 shows a schematic configuration of a system for performing a sulfation roasting method using the residue treatment method according to this embodiment. The treatment system according to the present embodiment includes a sulfate roasting furnace 10 for carrying out a roasting step, a dissolution tank 20 and a solid-liquid separation tank 30 for carrying out an extraction step, and a residue processing method. And a separator 40. The nickel component 42 obtained by the separator 40 can be reused for the sulfation roasting by supplying it to the sulfation roasting furnace 10.

The sulfation roasting furnace 10 processes the raw material 11 containing the nickel-containing raw material by the sulfation roasting to convert the nickel content contained in the nickel-containing raw material into nickel sulfate. The raw material 11 supplied to the sulfation roasting furnace 10 may include a sulfur content lacking in the nickel-containing raw material, oxygen for oxidizing the sulfur content, and the like. In FIG. 1, for simplification, the supply paths of the respective raw materials 11 are not distinguished. An auxiliary substance or material may be supplied to the sulfate roasting furnace 10 together with the raw material 11 for the purpose of improving the conversion efficiency of the sulfate roasting.

A roasted product 12 containing a nickel sulfate compound is obtained by the sulfation roasting process. Water 21 is supplied to the roasted product 12 in the dissolution tank 20 to dissolve the nickel sulfate compound in water to obtain a melt 22 containing the nickel sulfate compound. Although details will be described later, it is preferable to cool the roasted product 12 by the cooling unit 13 before adding the water 21 to the roasted product 12. Further, the roasted product 12 may be crushed before adding the water 21 to the roasted product 12. The iron component contained in the roasted product 12 is insoluble in water, such as iron oxide and iron sulfide, so that the melt 22 contains a solid phase. Therefore, by separating the melt 22 into a solid phase and a liquid phase in the solid-liquid separation tank 30, a nickel sulfate solution 31 is obtained as a liquid phase, and a residue 32 containing iron oxide as a solid phase is separated. Further, if necessary, for example, to separate nickel sulfate from cobalt sulfate or the like, a nickel sulfate compound in which impurities such as cobalt are removed can be obtained by performing a purification step of the nickel sulfate solution 31.

The residue 32 contains nickel and iron oxide. By applying a centrifugal force to the residue 32, the nickel component and the iron oxide can be separated. Since the specific gravity of iron oxide is larger than the specific gravity of nickel component, the nickel component and iron oxide can be efficiently separated. The average particle size of the nickel component contained in the residue 32 may be different from the average particle size of the iron oxide. In the above-mentioned sulfated roasting, iron oxide tends to become fine. Therefore, the average particle size of the nickel component may be larger than the average particle size of iron oxide. The average particle diameter of the residue 32 is, for example, in the range of 50 μm to 150 μm. The nickel component is a component of the nickel-containing raw material that has not been converted into nickel sulfate, and is, for example, nickel sulfide or oxide. Examples of iron oxide include Fe ₂ O ₃ , FeO, and Fe ₃ O ₄ .

In the present embodiment, a separator 40 is provided to separate the residue 32. Examples of the separator 40 or its separation method include cyclone, centrifugal separation, and centrifugal filtration. Examples of the cyclone include a gas cyclone that uses a gas as a fluid, a liquid cyclone that uses a liquid as a fluid, and a hydrocyclone that uses water as a fluid. It is preferable to use water as the fluid because the difference in specific gravity from the residue 32 is small and the cost is low. It is preferable that water is added to the residue 32 and pressure-fed by the pump 33 to supply the residue 32 to the separator 40 as a residue liquid 34 in which the residue 32 is dispersed in water. The residue liquid 34 may include the residue 32 in a slurry form. In order to stabilize the concentration of the residue contained in the residual liquid 34, a pipe that circulates in a loop is provided between the solid-liquid separation tank 30 and the pump 33 so that a part of the residue or water contained in the residual liquid 34 can be collected. It may be returned to the solid-liquid separation tank 30. When a gas is used as the fluid, the solid fine powder residue 32 may be directly supplied to the separator 40.

In the separator 40, the iron oxide 41 and the nickel component 42 are separated. The particle diameter (classification point) that serves as a reference when the iron oxide 41 and the nickel component 42 are separated by the separator 40 is preferably about 100 to 150 μm. Examples of the classification point (separation limit particle diameter) of the coarse powder having a large particle diameter and the fine powder having a small particle diameter include, for example, 50% separated particle diameter and equilibrium particle diameter (particles in which the coarse powder and the fine powder have the same mass). Diameter), the minimum particle size in the coarse powder, the maximum particle size in the fine powder, and the like. For example, particles larger than 100 μm may be nickel 42, and particles smaller than 100 μm may be iron oxide 41. The inner surface of the separator 40 is preferably made of soft rubber or the like to improve wear resistance.

The separator 40 may be provided in one stage, or may be provided in two or more stages in series, such as a separator 40 having a large classification point and a separator 40 having a small classification point. In order to improve the processing capacity of the separator 40, a plurality of separators 40 are provided in parallel, and the path of the residual liquid 34 supplied from the solid-liquid separation tank 30 or the pump 33 is branched toward the plurality of separators 40. May be.

The nickel content 42 separated from the iron oxide 41 can be supplied to the sulfation roasting furnace 10 for processing. Thereby, the nickel content in the residue 32 can be effectively utilized. When the nickel content 42 is returned to the sulfation roasting furnace 10, if the nickel content 42 is dispersed in the liquid, it may be returned to the sulfation roasting furnace 10 as it is. Alternatively, the nickel content 44 may be supplied to the sulfation roasting furnace 10 after being processed by the processing device 43. As the processing device 43, when the separated nickel component 42 is dispersed in the gas, a device that disperses the nickel component 42 in water to form a slurry, or the separated nickel component 42 is water or the like. A drying device for drying the nickel component 42 when it is dispersed in a liquid may be used. When the processing device 43 makes the nickel component 42 into a slurry form, the nickel component 44 supplied to the sulfation roasting furnace 10 becomes a slurry form. When the processing device 43 dries the nickel component 42, the nickel component 44 supplied to the sulfation roasting furnace 10 is in a dry state.

In the sulfation roasting furnace 10, nickel sulfate (NiSO ₄ ) can be obtained as the roasted product 12 by the dry smelting method without the need for treatment by a hydrometallurgical method using liquid sulfuric acid. SO ₂ is generated as a gas by burning the sulfur content in the raw material 11 or the sulfur content supplied from the outside, and is brought into contact with the nickel content in the raw material 11 to produce nickel sulfate. For example, when a nickel matte containing Ni ₃ S ₂ and Ni is sulphated and roasted, the reaction formula with 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)

It is considered that when SO ₂ gas comes into contact with the surface of the particles, a salt of NiSO ₄ is deposited on the surface of the particles and the reaction proceeds. The volume of NiSO ₄ deposited at this time is larger than that of Ni ₃ S ₂ . Furthermore, the SO ₂ gas diffuses through the voids generated by the precipitation of NiSO ₄ , so that the internal Ni ₃ S ₂ is sulphated and roasted. The conversion of Ni ₃ S ₂ to NiSO ₄ causes volume expansion of the nickel component, and as a result, the particles are broken and a residue having a smaller particle size remains. The finer the particle size of the raw material 11, the faster the rate of conversion to NiSO ₄ , but the harder the nickel matte, the greater the energy required for fine pulverization. The crushing operation has problems of time and energy, and there are restrictions or limitations in preparing a nickel mat raw material having a small particle size. Further, as described above, after the NiSO ₄ coating film is formed on the surface of the raw material particles, the diffusion of SO ₂ gas becomes rate-determining and the efficiency of the conversion reaction decreases. For this reason, it is not easy to increase the residence time in the roasting furnace to increase the NiSO ₄ conversion rate to 100% in one sulfation roasting step, and the productivity is also reduced. Therefore, from the viewpoint of economic efficiency, the conversion rate should be kept within a certain range, and nickel sulfate which is easily dissolved from the roasted product 12 should be dissolved in the dissolution tank 20 and then the residue 32 should be subjected to sulfation roasting again. Is efficient. However, iron oxide produced by the oxidation of iron contained in the raw material 11 is mixed in the residue 32. Therefore, it is desirable to supply the

nickel components

42 and 44 obtained by separating the iron oxide 41 from the residue 32 to the sulfation roasting furnace 10.

The iron oxide contained in the residue 32 is generated as the fine particles of the raw material 11 are cracked under the above-mentioned circumstances, and therefore, they are ultrafine particles having a very small particle size, and generally, filtration is difficult. Although there are various filtration methods, for example, when pressure filtration, vacuum filtration, or the like is adopted, it is difficult to separate the nickel component unless a filter aid is used. Therefore, in the separator 40, a centrifugal force is applied to the residue 32 to separate the nickel component and the iron oxide, so that the iron oxide 41 and the nickel component 42 can be easily separated.

When the

nickel components

42, 44 are in a slurry state when the

nickel components

42, 44 are supplied to the sulfation roasting furnace 10, the

nickel components

42, 44 can be easily transported and the inside of the sulfation roasting furnace 10 can be easily transported. Water vapor can be generated with. Therefore, the efficiency of generating the sulfur oxides required for the sulfation roasting by oxidizing them from the sulfur source is improved. When supplying the

nickel components

42, 44 to the sulfation roasting furnace 10, if the

nickel components

42, 44 are in a dry state, the weight of the

nickel components

42, 44 can be reduced during transportation, and the loss can be reduced. it can.

When the

nickel components

42 and 44 are dried, it is also possible to dry them by exhaust heat of the sulfation roasting furnace 10. Thereby, the energy recovery rate can be improved. As a method of transporting the exhaust heat of the sulfation roasting furnace 10 to the processing device 43 for drying the nickel content 42, a transport pipe for a heat medium such as hot water or steam or a heat transport path such as a heat pipe (not shown) May be connected to the sulfation roasting furnace 10. Alternatively, the waste heat of the sulfation roasting furnace 10 may be accumulated in the heat storage material as latent heat such as a phase change, and the stored heat storage material may be transported to the processing device 43 and used for drying.

The ratio of the nickel component contained in the nickel sulfate solution 31 and the nickel component contained in the residue 32 is not particularly limited after passing through the sulfation roasting step and the water dissolution step, but the nickel content contained in the residue 32 is from several% to several percent. Even if it becomes 10%, the nickel content contained in the residue 32 is separated from the iron content and then returned to the sulfation roasting furnace 10 to continue the treatment, thereby obtaining the nickel sulfate solution 31 from the nickel content of the raw material 11. The rate can be improved.

The sulfuric acid roasting furnace 10 from which the residue 32 is discharged and the sulfuric acid roasting furnace 10 from which the

nickel components

42 and 44 separated from the residue 32 are supplied may be the same sulfuric acid roasting furnace 10. However, different sulfation roasting furnaces 10 may be used. It is preferable to carry out the sulfation roasting method for obtaining nickel sulfate from a nickel-containing raw material containing iron under a predetermined condition in any of the sulfation roasting furnaces 10. Next, preferable conditions of the sulfation roasting method will be described in more detail. In addition, the nickel component in the sulfation roasting step includes the nickel component contained in the nickel-containing raw material of the raw material 11 and the

nickel components

42 and 44 separated from the residue 32.

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. 2 is an example of a conceptual state diagram of Ni—S—O system and 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. 2 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. 2 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. 2, 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. 2, 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. 2, 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 Nickel sulfate is a thermodynamically stable phase in the —SO system and iron oxide is a Fe—S—O system. 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. 2, 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.

As the SO ₂ partial pressure in the sulfation roasting step, the common logarithm of the SO ₂ partial pressure in atmospheric pressure (atm) log p(SO ₂ ) is preferably in the range of −1 to +1 and log p(SO ₂ ) is − The range of 1 to 0 is more preferable. In the overlapping region A in FIG. 2, 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, for example, by controlling the supply amount of the sulfur source. When the nickel-containing raw material has a low sulfur content, the sulfur content may be supplied to the sulfation roasting step. 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 ). When the sulfur source is sulfur (S), it is preferable to generate SO ₂ gas in an oxygen-enriched state. Sulfur oxides may be generated by burning sulfur in an atmosphere containing oxygen.

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, log p(O ₂ ) is about -1 to 0, log p(SO ₂ ) is -4 to 0 is mentioned.

Next, the purification of nickel sulfate obtained by sulfation roasting and the like will be described in more detail. The water 21 added to the roasted product 12 in the dissolving tank 20 in the water dissolving step is preferably pure water 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, it is preferable that the melt 22 obtained in the water dissolving step has a concentration at which NiSO ₄ does not precipitate even at room temperature, and it is preferable to maintain the heated state of the melt 22 when the concentration of NiSO ₄ is higher than that. In order to adjust the temperature of the melt 22, it is preferable to adjust the temperature of the roasted product 12 or the temperature of the water 21 before performing the melting operation. The residual heat of the roasted product 12 may be used as at least a part of the heat source that maintains the heated state of the melt 22. Therefore, the temperature of the roasted product 12 before being dissolved in the water 21 is preferably set to an appropriate temperature.

As described above, in the system shown in FIG. 1, the cooling unit 13 is provided between the sulfation roasting furnace 10 and the melting tank 20. The cooling unit 13 may be a batch type or a continuous type. In the case of the batch method, the roasted product 12 may be allowed to stand without being added with water until the temperature thereof decreases to a desired temperature. In the case of the continuous type, for example, the cooling unit 13 may be provided in the pipe connecting between the sulfation roasting furnace 10 and the dissolution tank 20. In the cooling unit 13, for example, a heat exchanger may be provided to recover excess residual heat from the roasted product 12, and the recovered residual heat may be used as various heat sources.

Depending on the state of the roasted product 12 obtained from the sulfation roasting furnace 10 or the state change during cooling in the cooling unit 13, the particles of the roasted product 12 are solidified, or the particles are A water-insoluble film may be formed on the surface of the. Therefore, a step of crushing the roasted product 12 may be added before adding the water 21 to the roasted product 12. The crushing means for the roasted product 12 is not particularly limited, but one or more of a ball mill, a rod mill, a hammer mill, a fluid energy mill, a vibration mill and the like can be used. Grinding of the roasted product 12 may be started before cooling the roasted product 12 or may be started after cooling the roasted product 12.

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, the solid-liquid separation tank 30 is a device having a high performance of separating solid-phase fine particles to be the residue 32. For example, one or two kinds such as a filtration tank, a centrifugal separation tank, a sedimentation tank, and a precipitation tank. The above is mentioned. 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 condition in which the iron content is less likely to be iron sulfate is set, and therefore, the nickel sulfate solution 31 having a low iron content can be obtained through the water dissolution and the solid-liquid separation. The residue 32 containing iron oxide or the like after separating the nickel sulfate solution 31 can be reused as the iron content of cement. Further, the iron oxide 41 separated from the residue 32 can be used for producing pig iron or the like as an iron-making raw material using a smelting reduction furnace, an electric furnace or the like, or for pigments, ferrites, magnetic materials, sintered materials and the like. .. 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 nickel sulfate solution 31 obtained through water dissolution and solid-liquid separation has a nickel sulfate compound as a main component, it is 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. be able to. Depending on the application, if it is desired to reduce, for example, cobalt sulfate, etc. as impurities in the nickel sulfate solution 31, solvent extraction, electrodialysis, electrowinning, electrorefining, electrorefining, Technologies such as ion exchange and 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 or the like, 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 sulfation roasting method of the present embodiment, the following effects can be obtained.
(1) The nickel content contained in the residue can be effectively used to improve the yield of the nickel sulfate compound.
(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 it is possible to accelerate the conversion reaction of the nickel-containing raw material, 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.

The above residue treatment method can also be used to treat residues discharged from a process different from the sulfate roasting.

<Experimental example>
A nickel matte containing iron (Ni ₃ S ₂ ) was roasted with a sulfation roasting tester. The roasting conditions were a roasting temperature of 650° C., a log p(O ₂ ) of −2.0, and a log p(SO ₂ ) of −2.0. The roasted product obtained was dissolved in pure water at a temperature of 80°C. The obtained dissolved material was allowed to stand for 1 hour, and the residue containing the nickel sulfate solution and iron oxide in the supernatant was separated by a filtration device using MILLIPORE (registered trademark). The residue remaining on the filtration membrane was dried in a thermostat bath at 110° C. for 2 hours, and the average particle size was measured with a Luzex (registered trademark) image analysis type particle size distribution analyzer manufactured by Nireco Corporation. As a result, the average particle size (p50) was 100 to 150 μm. In addition, as a result of analyzing the dried product with an electron beam microanalyzer (EPMA), the fraction having a larger particle size was nickel and the fraction having a smaller particle size was iron oxide.

From the preliminary study of the phase diagrams of Ni—S—O system and Fe—S—O system, log p(O ₂ ) was -2.0 and log p(SO ₂ ) was -2.0 at roasting temperature of 650°C. The condition of 2.0 is considered suitable for conversion to NiSO ₄ .

<Example 1>
The nickel matte was sulphated and roasted under the same conditions as in the above experimental example, and the obtained roasted product was dissolved in pure water at a temperature of 80°C. The obtained dissolved material was allowed to stand for 1 hour, and the residue containing the nickel sulfate solution and iron oxide in the supernatant was separated by a filtration device using MILLIPORE (registered trademark). The residue remaining on this filtration membrane was dispersed in pure water to obtain a dispersion liquid of the residue. The pump pressure (discharge pressure) was set to 1.0 kgf/cm ² and the flow rate of 38.0 L/min was used to cyclone the dispersion liquid of the residue (a hydrocyclone made by Lhasa Kogyo Co., Ltd.: Super-150-Cyclone alone). The amount of treatment at the time of being used was 2.2 m ³ /h. The pump pressure was changed to change the amount of the dispersion liquid of the residue supplied to the cyclone, and the treatment amount was changed as shown in Table 1. Note that 1 kgf/cm ² is 9.80665 N/cm ^2, that is, 98066.5 Pa.

<Example 2>
A dispersion liquid of the residue was obtained in the same manner as in Example 1. The pump pressure (discharge pressure) was set to 1.0 kgf/cm ^2, and the dispersion liquid of the residue was cyclone at a flow rate of 228 L/min (6 sets of hydrocyclone manufactured by Lhasa Kogyo Co., Ltd.: Super-150-Cyclone in parallel). The amount of treatment when it was subjected to 13.6 m ³ /h. The pump pressure was changed to change the amount of the dispersion liquid of the residue supplied to the cyclone, and the treatment amount was changed as shown in Table 2.

In Tables 1 and 2, the separation efficiency (%) is the weight ratio of the nickel content with the total of the nickel content recovered from the cyclone and the iron oxide as 100%. Iron oxide with a small particle size was separated upward from the center of the cyclone, and nickel with a large particle size was separated downward from the peripheral wall of the cyclone. When the amount of cyclone treated was large, the fluctuation range of the separation efficiency was slightly increased.

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... Sulfating roasting furnace, 11... Raw material, 12... Roasting product, 13... Cooling part, 20... Melting tank, 21... Water, 22... Melted material, 30... Solid-liquid separation tank, 31... Nickel sulfate solution , 32... Residue, 33... Pump, 34... Residual liquid, 40... Separator, 41... Iron oxide, 42, 44... Nickel content, 43... Treatment device.

Claims

A method for treating a residue, characterized in that the residue containing nickel and iron oxide is subjected to centrifugal force to separate the nickel and iron oxide.
The residue treatment method according to claim 1, wherein the average particle size of nickel and the average particle size of iron oxide are different.
The residue treatment method according to claim 1 or 2, wherein the average particle size of the nickel component is larger than the average particle size of the iron oxide.
The residue treatment method according to any one of claims 1 to 3, wherein the average particle size of the residue is within a range of 50 µm to 150 µm.
The residue shows that the oxygen partial pressure and the sulfur dioxide partial pressure are such that nickel sulfate is thermodynamically more stable than nickel oxide in the Ni—S—O system, and iron oxide is more than iron sulfate in the Fe—S—O system. The residue treatment method according to any one of claims 1 to 4, wherein the residue is obtained by sulfation roasting under a thermodynamically stable condition.
6. The residue treatment method according to any one of claims 1 to 5, wherein the nickel component obtained by separating iron oxide from the residue is treated in a sulfation roasting furnace.
The residue treatment method according to claim 6, wherein a nickel component obtained by separating iron oxide from the residue is supplied to the sulfation roasting furnace in a slurry state.
The residue treatment method according to claim 6, wherein the nickel component obtained by separating iron oxide from the residue is dried and supplied to the sulfation roasting furnace.
9. The residue treatment method according to claim 8, wherein the nickel component obtained by separating iron oxide from the residue is dried by exhaust heat of the sulfation roasting furnace.
In the sulfate roasting furnace, 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 iron oxide is in the Fe—S—O system. 10. The residue treatment method according to any one of claims 6 to 9, wherein the condition is that thermodynamically more stable than iron sulfate.
A roasting step of treating a nickel-containing raw material containing iron in a sulfation roasting furnace,
An extraction step of extracting a nickel sulfate compound from the roasted product obtained in the roasting step,
A residue treatment step of treating a residue obtained after extracting the nickel sulfate compound in the extraction step with the residue treatment method according to any one of claims 1 to 10 to separate a nickel component and an iron oxide. When,
A recycling step of supplying the nickel component obtained in the residue treatment step to a sulfation roasting furnace used in the roasting step,
A method for sulphating and roasting, comprising: