AU2019331801B2 - Method for producing nickel sulfate compound - Google Patents

Abstract

A method for producing a nickel sulfate compound, said method comprising a roasting step for heating a nickel-containing starting material which also contains iron under such conditions, wherein an oxygen partial pressure p(O

Description

DESCRIPTION METHOD FOR PRODUCING NICKEL SULFATE COMPOUND

Technical Field

[0001]

The present invention relates to a nickel sulfate

compound manufacturing method.

This application claims priority to Japanese Patent

Application No. 2018-161837 filed August 30, 2018, the

contents of which are hereby incorporated by reference.

Background Art

[0002]

In the related art, a nickel sulfate compound is

used as a raw material of various nickel compounds and

metal nickel for use in, for example, electrolysis nickel

plating, electroless nickel plating, and catalyst

materials. The recent demand of secondary batteries using

a nickel compound or metal nickel in a positive electrode

material is expected to expand as a power supply of

transport machines, such as electric vehicles, and

electronic devices. To produce high-performance secondary

batteries, there is a need to stably supply a high-purity

nickel sulfate compound.

[0003]

Examples of impurities that may be contained in low purity nickel compounds include other metal compounds, such as iron, copper, cobalt, manganese, and magnesium compounds. Examples of conventional methods for producing a high-purity nickel compound include a solvent extraction method. The solvent extraction method involves removing other metal compounds by selective extraction or taking a nickel compound out by selective extraction. In both cases, a particular agent is needed to selectively extract particular metal ions, resulting in high costs.

[0004]

Known methods for manufacturing nickel sulfate also

include a method in which the anion of a nickel compound is

exchanged with a sulfate ion through ion exchange, and a

method in which a nickel metal powder is dissolved in a

sulfuric acid solution with hydrogen gas generated. Patent

Literature 1 describes a method for producing water-soluble

nickel sulfate. The method involves heating, in sulfuric

acid, a green nickel oxide powder having a specific gravity

of higher than 6.30 and then leaching the reaction mass

with hot water. In Patent Literature 1, examples of

sulfuric acid used in the heat treatment include a 30% to

60% sulfuric acid solution (Claims 1 to 5) and 95%

concentrated sulfuric acid (Claims 6 to 7). The use of 95%

concentrated sulfuric acid (Examples 7 to 9) in Patent

Literature 1 needs a high temperature of 2750C or higher.

Citation List

Patent Literature

[00051

Patent Literature 1: US 3002814

Summary of Invention

Technical Problem

[00061

A method for producing nickel sulfate using sulfuric

acid in the liquid phase may be associated with concerns

about, for example, consumption of a large amount of

sulfuric acid due to dissolution of iron, which is present

together with nickel in the raw material, in sulfuric acid,

and possible generation of hydrogen gas during the

reaction.

[0007]

In light of the above circumstances, the present

invention may provide a nickel sulfate compound

manufacturing method that enables the manufacture of the

nickel sulfate compound even under a gas phase atmosphere.

Solution to Problem

[00081

A first aspect of the present invention is a nickel sulfate compound manufacturing method including a roasting step of producing a nickel sulfate compound by heating a nickel-containing raw material containing iron at an oxygen partial pressure and a sulfur dioxide partial pressure under which nickel sulfate is more thermodynamically stable than nickel oxide in a Ni-S-O system, and iron oxide is more thermodynamically stable than iron sulfate in an Fe-S o system.

[0009]

A second aspect of the present invention is the

nickel sulfate compound manufacturing method according to

the first aspect, wherein in the roasting step, the

roasting temperature is in the range of from 4000C to

7500C.

[0010]

A third aspect of the present invention is the

nickel sulfate compound manufacturing method according to

the first or second aspect, wherein in the roasting step,

the common logarithm log p(02) of the oxygen partial

pressure in terms of atmosphere (atm) unit is in the range

of from -4 to -6, and the common logarithm logp(S02) of

the sulfur dioxide partial pressure in terms of atmosphere

(atm) unit is in the range of from -1 to +1. It is noted

that the common logarithm is the logarithm (logio) with

base 10.

[0011]

A fourth aspect of the present invention is the

nickel sulfate compound manufacturing method according to

any one of the first to third aspects further including,

after the roasting step, a water dissolution step of

dissolving the nickel sulfate compound in water.

[0012]

A fifth aspect of the present invention is the

nickel sulfate compound manufacturing method according to

the fourth aspect further including, after the water

dissolution step, a solid-liquid separation step of

separating a liquid phase containing the nickel sulfate

compound and a solid phase containing iron.

[0013]

A sixth aspect of the present invention is the

nickel sulfate compound manufacturing method according to

any one of the first to fifth aspects, wherein the nickel

containing raw material contains at least one selected from

the group consisting of nickel sulfide ores, nickel

sulfide, nickel matte, nickel oxide, and ferronickel.

[0014]

A seventh aspect of the present invention is the

nickel sulfate compound manufacturing method according to

any one of the first to sixth aspects further including,

before the roasting step, an oxidation roasting step of performing oxidation roasting on the nickel-containing raw material under conditions different from those of the roasting step.

Advantageous Effects of Invention

[0015]

According to the first aspect, even when the nickel

containing raw material contains iron, nickel is converted

into a nickel sulfate compound while the conversion from

iron into iron sulfate is suppressed. This can reduce

consumption of sulfur by iron to improve the efficiency of

producing the nickel sulfate compound.

[0016]

According to the second aspect, the reduction of

iron is suppressed, and iron in the form of iron oxide,

iron sulfide, and the like may be present together with the

nickel sulfate compound. This can suppress the coagulation

of particles in the roasted product and facilitate the

processing in the later step.

[0017]

According to the third aspect, the production of the

nickel sulfate compound can be promoted under the

conditions of low oxygen partial pressure and high sulfur

dioxide partial pressure.

[0018]

According to the fourth aspect, it is easy to remove

iron by preferentially dissolving the nickel sulfate

compound.

[0019]

According to the fifth aspect, it is easy to remove

impurities containing iron from the nickel sulfate compound

through the solid-liquid separation step.

[0020]

According to the sixth aspect, the use of relatively

easily available nickel-containing raw materials can

improve productivity.

[0021]

According to the seventh aspect, iron, sulfur, and

the like contained in the nickel-containing raw material

can be oxidized before the roasting step. This can improve

the efficiency of separating impurities after the roasting

step.

Brief Description of Drawings

[0022]

Fig. 1 is a conceptual phase diagram of a Ni-S-O

system and an Fe-S-O system.

Fig. 2 is a schematic flow diagram of a nickel

sulfate compound manufacturing method according to an embodiment.

Fig. 3 is a structural diagram illustrating an

apparatus used in Examples.

Description of Embodiments

[0023]

The present invention will be described below on the

basis of preferred embodiments.

[0024]

A nickel sulfate compound manufacturing method

according to an embodiment includes a roasting step of

producing a nickel sulfate compound by heating a nickel

containing raw material at an oxygen partial pressure and a

sulfur dioxide partial pressure under which nickel sulfate

is more thermodynamically stable than nickel oxide in a Ni

S-O system, and iron oxide is more thermodynamically stable

than iron sulfate in an Fe-S-O system, as illustrated in

Fig. 1.

[0025]

Fig. 1 is an example conceptual phase diagram of a

Ni-S-O system and an Fe-S-O system. The boundary lines

between phases in the Ni-S-O system are denoted by dashed

lines (-----), and the boundary lines between phases in the

Fe-S-O system are denoted by dash-dotted lines (-----)

The chemical formulas along with the arrows each represent a thermodynamically stable phase extending from the corresponding boundary line in the direction of the arrow.

The horizontal axis of the phase diagram illustrated in

Fig. 1 represents the logarithm of the 02 partial pressure.

The 02 partial pressure increases toward the right side,

and the 02 partial pressure decreases toward the left side.

The vertical axis of the phase diagram illustrated in Fig.

1 represents the logarithm of the SO 2 partial pressure.

The S02 partial pressure increases toward the upper side,

and the SO 2 partial pressure decreases toward the lower

side. The unit of the partial pressure is, for example,

atmosphere (atm = 101325 Pa).

[0026]

In the Ni-S-0 system, examples of nickel sulfate

include NiSO 4 , and examples of nickel oxide include NiO.

In the phase diagram illustrated in Fig. 1, the boundary

line LNi represents a boundary line between a region in

which nickel sulfate is thermodynamically stable and a

region in which nickel oxide is thermodynamically stable.

In the region having higher SO 2 partial pressure and higher

02 partial pressure than the boundary line LNi, nickel

sulfate is a thermodynamically stable phase. In the region

having lower SO 2 partial pressure and lower 02 partial

pressure than the boundary line LNi, nickel oxide is a

thermodynamically stable phase.

[0027]

In the Fe-S-0 system, examples of iron sulfate

include FeSO4 and Fe2(S04) 3 , and examples of iron oxide

include Fe203. In the phase diagram illustrated in Fig. 1,

the boundary line LFe represents a boundary line between a

region in which iron sulfate is thermodynamically stable

and a region in which iron oxide is thermodynamically

stable. In the region having higher SO 2 partial pressure

and higher 02 partial pressure than the boundary line LFe,

iron sulfate is a thermodynamically stable phase. In the

region having lower SO 2 partial pressure and lower 02

partial pressure than the boundary line LFe, iron oxide is

a thermodynamically stable phase.

[0028]

According to the phase diagram illustrated in Fig.

1, in a region A having lower SO 2 partial pressure and

lower 02 partial pressure than the boundary line LFe and

having higher SO 2 partial pressure and higher 02 partial

pressure than the boundary line LNi, nickel sulfate is a

thermodynamically stable phase in the Ni-S-0 system, and

iron oxide is a thermodynamically stable phase in the Fe-S

system. Thus, roasting a system containing nickel (Ni),

oxygen (0), and sulfur (S) under the conditions of the

overlapping region A can convert nickel into nickel sulfate

while suppressing generation of iron sulfate even when the system contains iron.

[0029]

The roasting temperature is preferably in the range

of from 4000C to 750°C, and more preferably in the range of

from 5500C to 750°C. At such a roasting temperature, the

reduction of iron is suppressed, and iron in the form of

iron oxide, iron sulfide, and the like may be present

together with the nickel sulfate compound. This can

suppress the coagulation of particles in the roasted

product and facilitate the processing in the later step.

Since the carbonate decomposes at this temperature, the

carbonate even if present can be prevented from remaining

as an impurity as a result of dissolution in water. This

facilitates the processing in the later step.

[0030]

Regarding the 02 partial pressure in the roasting

step, the common logarithm log p(02) of the 02 partial

pressure in terms of atmosphere (atm) unit is preferably in

the range of from -4 to -6, and log p(02) is more

preferably in the range of from -5 to -6. As the 02

partial pressure decreases, the SO 2 partial pressure tends

to increase in the overlapping region A in Fig. 1. This

can promote production of nickel sulfate while suppressing

generation of iron sulfate.

[0031]

Regarding the SO 2 partial pressure in the roasting

step, the common logarithm logp(S02) of the SO 2 partial

pressure in terms of atmosphere (atm) unit is preferably in

the range of from -1 to +1, and logp(S02) is more

preferably in the range of from -1 to 0. In the

overlapping region A shown in Fig. 1, the generation of the

sulfate can be promoted by increasing the SO 2 partial

pressure. Furthermore, when the SO 2 partial pressure is in

the range of about normal pressure or lower (the common

logarithm of the partial pressure is substantially 0 or

lower), the total pressure of the roasting atmosphere is

not too high, and it is easy to handle the equipment.

[0032]

The nickel-containing raw material may be a nickel

compound or metal nickel as long as it contains metal

nickel. The nickel-containing raw material in the roasting

step preferably contains at least one selected from the

group consisting of nickel sulfide ores, nickel sulfide,

nickel matte, nickel oxide, and ferronickel. The nickel

containing raw material may contain iron or may not contain

iron. Iron is separated from the nickel sulfate compound

in the later step, but the raw material preferably contains

as little iron as possible in view of energy consumption.

The nickel-containing raw material may be used alone or in combination of two or more. When two or more nickel containing raw materials are used, these raw materials may be supplied in the form of a mixture or may be supplied separately.

[0033]

Examples of nickel matte include a nickel matte

having a composition (by weight ratio) with 45% to 55% Ni,

about 20% Fe, 20% to 25% S, and about 1% or less Co.

Examples of nickel matte having a nickel concentration

increased in a converter include a nickel matte having a

composition (by weight ratio) with about 78% Ni, about 1%

Co, about 1% Fe, and about 20% S. Examples of ferronickel

include a ferronickel having a composition (by weight

ratio) with 18% to 23% Ni, about 1% Co, and 76% to 81% Fe.

[0034]

Prior to the roasting step, the particle size of the

nickel-containing raw material is preferably reduced by

chipping, grinding, abrasion, or other process. Since the

reaction starts from the surface of the raw material in the

roasting step, a smaller particle size of the raw material

results in a shorter reaction time, which is preferred.

The grinding unit is not limited but may be one or a

combination of two or more selected from a ball mill, a rod

mill, a hammer mill, a fluid energy mill, and a vibrating

mill. The particle size after grinding is not limited but may be, for example, from about 1 to 1000 pm or from about

10 to 100 pm. A raw material available in the form of fine

particles, such as limonite ore, may be supplied to the

roasting step without any processing.

[0035]

Examples of the roasting apparatus that performs the

roasting step include, but are not limited to, a rotary

kiln, a fluidized bed heating furnace, and an electric

furnace. To maintain the 02 partial pressure low in the

roasting apparatus, an inert gas, such as nitrogen (N2 ) or

argon (Ar), may be supplied to the roasting apparatus.

These inert gases can also be used as a carrier for

supplying a volatile component, such as gas or steam, to

the roasting apparatus. When the nickel-containing raw

material has a low sulfur content, sulfur may be supplied

to the roasting step. Examples of sulfur sources include,

but are not limited to, element sulfur, sulfur oxides,

sulfuric acid, sulfates, and sulfides.

[0036]

Prior to the roasting step under the conditions of

the overlapping region A, a preliminary oxidation roasting

step under conditions different from those of the roasting

step may be carried out in order to, for example, oxidize

iron, sulfur, and the like contained in the raw material.

In the preliminary oxidation roasting step, 02 gas or the like may be supplied as an oxidizing agent.

[0037]

Fig. 2 illustrates a schematic flow of the nickel

sulfate compound manufacturing method according to this

embodiment. A roasted product 11 containing a nickel

sulfate compound is produced through a roasting step S1 of

a nickel-containing raw material 10 described above. A

solution 21 containing the nickel sulfate compound is

formed through a water dissolution step S2 of dissolving

the nickel sulfate compound in water by supplying water 20

to the roasted product 11. Since iron contained in the

roasted product 11 is present in water-insoluble forms,

such as iron oxide and iron sulfide, as described above,

the separation of the solution 21 into a solid phase and a

liquid phase in a solid-liquid separation step S3 provides

a crude nickel sulfate compound 31 as a liquid phase and

causes impurities 32 containing iron and the like to be

separated as a solid phase. As necessary, a purifying step

S4 is further performed by adding a purifying agent 40 to

the crude nickel sulfate compound 31 in order to remove

coexisting substances, such as cobalt, thereby yielding a

purified nickel sulfate compound 41 without impurities 42,

such as cobalt.

[0038]

Water added to the roasted product in the water dissolution step is preferably pure water treated so as not to contain impurities. The water treatment method is not limited but may be, for example, one or more selected from filtration, membrane separation, ion exchange, distillation, sterilization, chemical treatment, and adsorption. Water for dissolution may be, for example, clean water obtained from water sources, or industrial water or may be water obtained by treating wastewater generated in other process. Two or more types of water may be used.

[0039]

The solubility of nickel sulfate in water is the

highest at 1500C. At 1500C, 55 g NiSO 4 is contained in 100

g of the solution, and even at 00C, 22 g NiSO 4 is contained

in 100 g of the solution. For this, the dissolving process

is preferably performed at a temperature equal to or lower

than the boiling point of water. The solution obtained in

the water dissolution step preferably has a NiSO 4

concentration at which NiSO 4 does not precipitate even at

normal temperature. The solution having a NiSO 4

concentration higher than this concentration is preferably

maintained in a heated state.

[0040]

In the solid-liquid separation step, examples of the

solid-liquid separation process include, but are not limited to, filtration, centrifugation, and sedimentation.

Desirably, an apparatus having a great ability to separate

fine particles contained in the solid phase is preferably

used. For example, in filtration, the type of filtration

is not limited, and examples of the type of filtration

include gravity filtration, reduced pressure filtration,

pressure filtration, centrifugal filtration, filtration

with addition of filter aid, and squeeze filtration.

Pressure filtration in which it is easy to control

differential pressure and which enables rapid separation is

preferred.

[0041]

Examples of impurities that may be present together

with the nickel sulfate compound include iron (Fe), cobalt

(Co), and aluminum (Al). In the case where salts of these

metals are sulfates in the roasting step and when the

nickel sulfate compound is dissolved in water, iron

sulfate, cobalt sulfate, and the like are also dissolved.

Furthermore, for example, iron in the form of oxides, such

as FeOOH, Fe203, and Fe304, or other form precipitates in

water, and it is easy to remove impurities from the nickel

sulfate compound. Since the roasting step in this

embodiment is set to conditions under which iron is

unlikely to form iron sulfate, a crude nickel sulfate

compound having a low iron content is obtained after the solid-liquid separation step.

[0042]

Among impurities, metals having lower ionization

tendency than hydrogen (H), such as copper (Cu), gold (Au),

silver (Ag), and platinum-group metals (PGM), remain as

solid in the water dissolution step and thus can be removed

by the solid-liquid separation step. The solid removed by

the solid-liquid separation step may contain compounds of

arsenic (As), lead (Pb), zinc (Zn), and the like, in

addition to the above impurities. The solid containing

these impurities can be recycled as a valuable resource.

[0043]

The solutions obtained in the water dissolution step

and the solid-liquid separation step contain the nickel

sulfate compound as a main component. The solutions of the

nickel sulfate compound can be transported and used without

any processing or after being, for example, dried to form a

solid of the nickel sulfate compound. In the case where it

is preferred to reduce the amount of, for example, cobalt

sulfate and the like, which are impurities in the solution,

depending on the application, techniques, such as solvent

extraction, electrowinning, electrorefining, ion exchange,

crystallization, can be used.

[0044]

In solvent extraction, an extractant capable of extracting cobalt more preferentially or selectively than nickel is preferably used. The use of such an extractant allows the nickel sulfate compound to remain in an aqueous solution and enables efficient purification. Examples of the extractant include organic compounds having a functional group that may be bonded to a metal ion, such as phosphinic acid group or thiophosphinic acid group. In solvent extraction, an organic solvent capable of separating the extractant from water may be used as a diluent. By dissolving the extractant bonded to a metal ion, such as cobalt ion, in a diluent, it is easy to separate impurities from an aqueous solution containing the nickel sulfate compound without using a large amount of the extractant. The diluent is preferably an organic solvent immiscible with water.

[0045]

In crystallization, at least one factor selected

from a change in temperature, a decrease in solvent volume,

addition of other substance, and the like may cause

crystallization of the nickel sulfate compound of interest

from the solution. In this method, at least part of

impurities is allowed to remain in the liquid phase, which

makes purification possible. Specific examples include

evaporation crystallization and poor solvent

crystallization. The evaporation crystallization involves concentrating the solution by boiling or evaporation under reduced pressure to crystallize the nickel sulfate compound. The poor solvent crystallization is a crystallization process used in pharmaceutical manufacturing and involves, for example, adding an organic solvent to a solution containing the nickel sulfate compound to precipitate the nickel sulfate compound. The organic solvent used in crystallization is preferably an organic solvent compatible with water. The organic solvent is, for example, at least one selected from the group consisting of methanol, ethanol, propanol, isopropanol, butyl alcohol, ethylene glycol, and acetone. Two or more organic solvents may be used. The concentration range in which the organic solvent is mixed with water is preferably such that the organic solvent is added to the extent that the nickel sulfate compound precipitates. The organic solvent can be mixed with water at any ratio as long as the nickel sulfate compound precipitates. The organic solvent added in the crystallization step is not limited to an anhydrous organic solvent and may be an organic solvent containing water to the extent that water does not hinder crystallization. The ratio of water to the organic solvent is not limited and may be set in the range of, for example, from 1 : 20 to 20 : 1. The ratio of water to the organic solvent is preferably about 1 : 1, for example, from 1 : 2 to 2 : 1.

[0046]

When the solid nickel sulfate compound is obtained

after crystallization or the like, the nickel sulfate

compound may be in the form of anhydrous, monohydrate,

dihydrate, pentahydrate, hexahydrate, or heptahydrate of

nickel sulfate. The nickel sulfate compound precipitated

by crystallization can be separated from the solution

through solid-liquid separation. Examples of the solid

liquid separation process include, but are not limited to,

filtration, centrifugation, and sedimentation. The metals

dissolved in the solution are preferably neutralized and

removed from the solution through precipitation and the

like. When the cleaned solution is mainly composed of a

mixture of water and an organic solvent, water and the

organic solvent can be separated from each other by

distillation or other process.

[0047]

The nickel sulfate compound manufacturing method

according to this embodiment provides the following

advantageous effects.

(1) A nickel sulfate compound with a high added

value can be manufactured from various nickel-containing

raw materials. This enables production near the site where

the nickel sulfate compound is in demand and results in low transportation costs.

(2) A high-purity nickel sulfate compound can be

produced.

(3) Generation of iron sulfate can be suppressed in

the roasting step. Generation of hydrogen (H 2 ) gas can

also be suppressed.

(4) In the roasted product, iron is in the form of

water-insoluble chemical species, and nickel in the form of

nickel sulfate compound easily dissolves in water. It is

thus easy to remove iron from the roasted product.

(5) It is easy to remove impurities containing iron.

(6) The equipment costs are lower than those in the

related art, and existing equipment can be used as a

roasting furnace.

(7) Iron contained in the nickel-containing raw

material can be oxidized before the roasting step, which

can improve the efficiency of iron removal.

[0048]

The present invention is described above on the

basis of preferred embodiments, but the present invention

is not limited to the above embodiments. Various

modifications are possible without departing from the

spirit of the present invention.

Examples

[0049]

The present invention will be described below in

detail by way of Examples.

[0050]

(Example-1: Roasting Test)

The sulfating roasting test was carried out using a

test apparatus 100 illustrated in Fig. 3. A nickel

compound was weighed to obtain 5 g of nickel compound as a

sample and placed on a receiving table 101. The receiving

table 101 was then set on the inner side of a glass case

102 installed in an electric furnace 103. The glass case

102 was equipped with a thermometer 104, such as a

thermocouple capable of measuring the temperature of an

atmosphere, an injection tube 105 through which various

gases can be injected, and an outlet 106 of waste gas

generated inside. The sample was heated to a predetermined

temperature and steamed in the electric furnace 103. From

the injection tube 105, argon gas was always injected,

while dry air or SO 2 gas containing nitrogen gas was

supplied at regular intervals. The waste gas discharged

from the outlet 106 was treated in a waste gas treatment

device 108 after passing through a gas analyzer 107. The

data about the amount of various gases and the analysis

values were collected in the computer.

[0051]

The nickel compound used in the test was a nickel

sulfide alloy produced by reducing the iron content of

nickel matte through processing in a converter. The

composition of the nickel compound was as described below.

Ni: 78%, Co: 1%, Fe: 1%, S: 20%

[0052]

Sulfating roasting was performed on 5 g of the

sample at 6800C. The sample was purged with argon gas for

20 minutes until the sample was heated to a predetermined

temperature. After the sample reached a predetermined

temperature of 6800C, the sample was burned with air

supplied for 20 minutes in order to oxidize iron. As soon

as air was injected, the weight of the sample was reduced,

and generation of SO 2 gas was observed. Subsequently, the

gas to be injected was switched to SO 2 , and sulfating

roasting was performed for 40 minutes while the 02 partial

pressure and the S02 partial pressure were controlled.

During sulfating roasting, a certain level of S02

consumption was observed. The roasted product was analyzed

by X-ray diffraction (XRD). As a result, it was found that

iron was converted into the form of Fe203 and Ni was

converted into the form of NiSO 4 .

[0053]

(Example-2: Water Dissolution Test)

The roasted product produced from 5 g of the nickel

compound in Example-1 was placed in 100 g of pure water and

dissolved by stirring at 900C. Part of the solution was

sampled, and the concentration of each metal (Ni, Fe, Co)

in the solution was obtained by using an atomic absorption

spectrometer. Furthermore, the amount of each metal in the

solution, that is, the total amount of each metal dissolved

in pure water, was determined from the obtained

concentration, and the percentage (dissolution percentage)

of each metal dissolved in pure water was obtained provided

that the amount of each metal contained in 5 g of the

sample used in sulfating roasting was 100%. For example,

the dissolution percentage of Ni means the percentage of Ni

dissolved in pure water relative to Ni contained in the

roasted product. The results of the dissolution percentage

are shown in Table 1.

[0054]

[Table 1]

Metal Dissolution Percentage Ni 85.0% Fe 0.1% Co 95.0%

[00551

These results indicate that iron in the roasted

product is hardly dissolved, and Ni and Co are easily

dissolved. This shows that a high-purity nickel sulfate

compound having low iron content can be manufactured by

sulfating roasting in Example-1.

Industrial Applicability

[00561

The present invention can be used to manufacture a

high-purity nickel sulfate compound useful as a raw

material of various nickel compounds and metal nickel used

in, for example, electric components of secondary batteries

and like, and chemical products.

[0057]

Throughout this specification and the claims which

follow, unless the context requires otherwise, the words

"comprise" and "include", and variations such as

"comprises", "comprising", "includes" and "including" will

be understood to imply the inclusion of a stated integer or

step or group of integers or steps but not the exclusion of

any other integer or step or group of integers or steps.

[00581

The reference to any prior art in this specification

is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia.

Reference Signs List

[0059]

Si Roasting step

S2 Water dissolution step

S3 Solid-liquid separation step

S4 Purifying step

Nickel-containing raw material

11 Roasted product

Water

21 Solution

31 Crude nickel sulfate compound

32 Impurities separated in solid-liquid separation step

Purifying agent

41 Purified nickel sulfate compound

42 Impurities separated in purifying step

Claims (7)

The claims defining the invention are as follows:

1. A nickel sulfate compound manufacturing method

comprising: a roasting step of producing a nickel sulfate

compound by heating a nickel-containing raw material

containing iron at an oxygen partial pressure and a sulfur

dioxide partial pressure under which nickel sulfate is more

thermodynamically stable than nickel oxide in a Ni-S-O

system, and iron oxide is more thermodynamically stable

than iron sulfate in an Fe-S-O system, wherein an inert gas

is separately supplied during the roasting step and a

roasting temperature in the roasting step is in a range of

from 4000C to 680°C.

2. The nickel sulfate compound manufacturing method

according to claim 1, wherein in the roasting step, a

common logarithm log p(02) of the oxygen partial pressure

in terms of atmosphere (atm) unit is in a range of from -4

to -6, and a common logarithm logp(S02) of the sulfur

dioxide partial pressure in terms of atmosphere (atm) unit

is in a range of from -1 to +1.

3. The nickel sulfate compound manufacturing method

according to claim 1 or 2, further comprising: after the

roasting step, a water dissolution step of dissolving the

nickel sulfate compound in water.

4. The nickel sulfate compound manufacturing method

according to claim 3, further comprising: after the water

dissolution step, a solid-liquid separation step of

separating a liquid phase containing the nickel sulfate

compound and a solid phase containing iron.

5. The nickel sulfate compound manufacturing method

according to any one of claims 1 to 4, wherein the nickel

containing raw material contains at least one selected from

the group consisting of nickel sulfide ores, nickel

sulfide, nickel matte, nickel oxide, and ferronickel.

6. The nickel sulfate compound manufacturing method

according to any one of claims 1 to 5, further comprising:

before the roasting step, an oxidation roasting step of

performing oxidation roasting on the nickel-containing raw

material under conditions different from those of the

roasting step.

7. The nickel sulfate compound manufacturing method

according to any one of claims 1 to 6, wherein the inert

gas is argon.