JP7191215B2 - Method for treating nickel-containing raw materials - Google Patents

Description

The present invention relates to a method for treating nickel-containing raw materials.

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, and the like. In recent years, as a power source for transportation equipment such as electric vehicles and electronic equipment, the demand for secondary batteries using a nickel compound or metallic nickel as a positive electrode material is expected to increase. A stable supply of high-purity nickel sulfate compounds is desired in order to obtain high-performance secondary batteries.

Impurities that can be included in low-purity nickel compounds include other metal compounds such as iron, copper, cobalt, manganese, magnesium, and the like. Conventional methods for obtaining high-purity nickel compounds include a method of dissolving metallic nickel whose purity has been increased by electrowinning with a sulfuric acid solution, and a solvent extraction method. Solvent extraction involves selectively extracting out other metal compounds or selectively extracting out nickel compounds. In either case, a special chemical is required to selectively extract specific metal ions, resulting in high costs.

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 heat-treating nickel oxide powder having a specific gravity exceeding 6.30 in sulfuric acid and then leaching it with hot water. . In Patent Document 1, sulfuric acid solutions with a concentration of 30% to 60% (claims 1 to 5) and concentrated sulfuric acid with a concentration of 95% (claims 6 to 7) are mentioned as the sulfuric acid used in the heat treatment. When using concentrated sulfuric acid with a concentration of 95% 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 nickel-containing raw material treatment method capable of efficiently treating even a nickel-containing raw material containing a high concentration of magnesium.

A first aspect of the present invention is a method for treating a nickel-containing raw material, comprising an oxidative roasting step of oxidizing and roasting a nickel-containing raw material containing magnesium to convert the magnesium content into magnesium oxide. be.

A second aspect of the present invention is characterized in that the nickel-containing raw material contains nickel ore, and has a magnesium removing step of removing the magnesium content from the nickel-containing raw material after the oxidizing roasting step. 1 is a method of processing a nickel-containing feedstock of an embodiment.

A third aspect of the present invention is a nickel-containing raw material according to the first or second aspect, characterized by having a step of pulverizing the nickel-containing raw material containing the magnesium content before the oxidizing roasting step. is a processing method.

A fourth aspect of the present invention is the method for treating a nickel-containing raw material according to the second aspect, wherein at least part of silica contained in the nickel ore is removed in the magnesium removing step.

A fifth aspect of the present invention is a sulfate roasting step of obtaining a roasted product containing nickel sulfate by sulfate roasting the nickel-containing raw material from which the magnesium content has been removed after the magnesium removal step. A method for treating a nickel-containing raw material according to the second or fourth aspect, characterized by having

A sixth aspect of the present invention is that the nickel-containing raw material contains iron, and the sulfated roasting step makes nickel sulfate more thermodynamically stable than nickel oxide in the Ni—S—O system, and A nickel-containing raw material according to a fifth aspect, characterized in that heat roasting is performed under conditions of oxygen partial pressure and sulfur dioxide partial pressure at which iron oxide is thermodynamically more stable than iron sulfate in the Fe—S—O system. is a processing method.

According to the first aspect, in the nickel-containing raw material after oxidizing roasting, the difference in properties between nickel oxide converted from nickel and magnesium oxide converted from magnesium is used in the post-process. can facilitate the processing of As a result, even a nickel-containing raw material containing a high concentration of magnesium can be efficiently treated.

According to the second aspect, by removing the magnesium content contained in the nickel-containing raw material, it is possible to facilitate the treatment of the nickel-containing raw material in the post-process.

According to the third aspect, the particle size of the nickel-containing raw material can be adjusted to promote oxidative roasting of the magnesium content in the nickel-containing raw material.

According to the fourth aspect, it is possible to facilitate the treatment of the nickel-containing raw material in the post-process by removing excess silica from the nickel-containing raw material.

According to the fifth aspect, since the nickel-containing raw material is treated by the pyrometallurgical method, there is no need to use liquid sulfuric acid, which facilitates the treatment.

According to the sixth aspect, the nickel content is converted to the nickel sulfate compound, and the conversion of the iron content to iron sulfate is suppressed, so the consumption of the sulfur content by the iron content is suppressed, and the production efficiency of the nickel sulfate compound is reduced. can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the outline of the processing method of the nickel containing raw material by embodiment. 1 is a conceptual phase diagram of Ni--S--O system and Fe--S--O system. FIG.

The processing method of the present embodiment has an oxidative roasting step of oxidizing and roasting a nickel-containing raw material containing magnesium to convert the magnesium into magnesium oxide.

The nickel-containing raw material may be a nickel compound or metallic nickel as long as it contains the nickel element. Nickel compounds include, but are not limited to, 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 (single substance or alloy) is used as the nickel-containing raw material, shots or the like obtained by breaking the molten metal into small pieces may be used. Nickel ores can also be used as nickel-containing raw materials. Nickel ores include one or more of nickel oxide ores and nickel sulfide ores. Nickel matte or the like containing nickel sulfide as a main component can also be used as the nickel-containing raw material.

Nickel oxide ores include laterite ores containing nickel such as limonite and saprolite. The limonite may be a limonite with a low iron content or a limonite with a high iron content. less than 1.8 wt%) saprolite. Examples of the nickel sulfide ore include sulfite nickel ore (pentland ore), needle nickel ore, chalcopyrite containing nickel, and pyrrhotite containing nickel.

The nickel-containing feedstock may or may not contain iron. When the nickel-containing raw material contains iron, the iron is separated from the nickel sulfate compound in a post-process. From the viewpoint of energy consumption, the lower the iron content in the raw material, the better. Although the treatment can be performed even if the iron content is higher than the nickel content, it is preferable that the iron content is lower than the nickel content. Nickel-containing raw materials are not limited to one type, and two or more types may be used. When two or more kinds of nickel-containing raw materials are used, these raw materials may be supplied in a mixed state, or may be supplied separately. For example, a nickel-containing raw material that does not contain sulfur may be used, and/or a nickel-containing raw material that contains sulfur, such as nickel sulfide ore, nickel sulfide, nickel matte, etc., may be used as at least part of the raw material. may

Nickel-containing feedstocks suitable for this embodiment include at least one nickel-containing feedstock containing a magnesium content. For example, nickel sulfide ores such as heazlewoodite and pentlandite are included in host rocks such as magnesium-containing serpentine. As an example, the ratio of nickel sulfide ore is about 0.2 to 5 wt %, and the particle size is about 2 μm to 1 mm. Also, when the ore contains a high concentration of magnesium-containing minerals such as dolomite and talc, the nickel-containing raw material may be contaminated with magnesium. Although the ratio of the nickel content and the magnesium content is not particularly limited, for example, Mg/Ni may be about 5 to 15 or 8 to 12.5, or more. When the nickel-containing raw material contains magnesium and iron, their ratio is not particularly limited, but Mg/Fe is about 0.6 to 2, for example. The nickel-containing raw material may contain a high concentration of magnesium content. For example, if the chemical formula of serpentine is Mg ₃ Si ₂ (OH) ₄ O ₅ , the proportion of Mg is about 26% by weight. The proportion of magnesium in the nickel-containing raw material is, for example, 10% by weight or more, and includes 15% by weight, 20% by weight, 25% by weight, 30% by weight, or ratios around or between these.

FIG. 1 shows a schematic configuration of a system for performing a sulfated roasting method using the processing method according to this embodiment. The treatment system of this embodiment comprises an oxidizing roasting furnace 12 for carrying out the oxidizing roasting process 10, a hydrating device 22 and classifier 24 for carrying out the magnesium removing step 20, and a sulfated roasting process 30. It includes a sulphating roaster 32 for carrying out the extraction process 40 and a cooling section 41 and a dissolution vessel 43 for carrying out the extraction process 40 .

Prior to the oxidizing roasting step 10, it is preferable to reduce the particle size of the nickel-containing raw material 11 by operations such as chopping, pulverizing, and attrition. Since the oxidation roasting reaction starts from the surface of the nickel-containing raw material 11, the smaller the particle size of the nickel-containing raw material 11, the shorter the reaction time, which is preferable. The means for pulverizing the nickel-containing raw material 11 is not particularly limited, but one or more of ball mills, rod mills, hammer mills, fluid energy mills, vibration mills, and the like can be used. The particle size of the nickel-containing raw material 11 after pulverization is not particularly limited. If the nickel-containing raw material is available in the form of fine particles such as limonite ore, it may be supplied to the oxidizing roasting step 10 as it is.

Examples of the oxidation roasting furnace 12 include a stirring roasting furnace, a rotary furnace roasting furnace, and a fluidized bed roasting furnace having a fluidized bed. As for the roasting of ores and the like, conventionally, mined ores are coarsely pulverized and then roasted using an agitation type roasting furnace or a rotary furnace type roasting furnace. In this case, the burden of pretreating the roasting object is small and the number of revolutions is slow, but the reaction speed is slow and the size of the apparatus is increased. For this reason, fluidized-bed roasting furnaces have become popular, in which the roasting object is roasted while floating in combustion air. By adopting a fluidized bed roasting furnace, the apparatus can be downsized. For the oxidation roasting furnace 12, an optimum method can be selected according to the characteristics of the ore to be treated. For example, when the ore is mainly composed of fine powder of limonite or the like, scattering of the fine powder can be suppressed by using a rotary furnace type roasting furnace.

The roasting temperature (oxidizing roasting temperature) in the oxidizing roasting step of the present embodiment is preferably 600° C. or higher, for example. Although the upper limit of the oxidizing roasting temperature is not particularly limited, an oxidizing roasting temperature of about 600 to 800° C. is mentioned from the viewpoint of the cost of the refractory material of the oxidizing roasting furnace 12 and the like. Compared with the case of discharging slag of about 1500 to 1550° C. in a smelting furnace, it is possible to treat at a relatively low temperature. Specific examples of the oxidative roasting temperature include 600°C, 650°C, 700°C, 750°C, 800°C, or temperature ranges around or between these. When the nickel-containing raw material 11 such as raw ore is pulverized before the oxidizing roasting step 10, it is preferable to pulverize it to a particle size of 30 mm or less, for example, about 150 μm. The structure of the oxidizing roasting furnace 12 is not particularly limited, but the inlet for the nickel-containing raw material 11 and the outlet for the oxidizing roasting product 13 may be provided on the side surface of the furnace body, for example, in an oblique direction. An outlet for the exhaust gas 14 may be provided in the upper part of the furnace body.

The cost can be reduced by supplying the raw ore to the oxidizing roasting process 10 using only a simple pretreatment method such as crushing without being treated by flotation. Ores such as serpentine are pulverized and then treated with flotation, where they become fine particles and migrate to the floating side in the same way as the metallic nickel content, separating and concentrating the nickel content from the host rock components it becomes difficult to Also, when the host rock components migrate to the sedimenting side, a large amount of nickel tends to accompany the host rock components, resulting in a large loss. Therefore, the recovery rate of the nickel content can be improved by treating the ore by oxidative roasting without flotation.

In the oxidizing roasting step 10, O ₂ gas, air, or the like may be supplied as an oxidizing agent. In the oxidative roasting product 13 obtained by oxidative roasting of the nickel-containing raw material 11 containing magnesium, the magnesium is converted to magnesium oxide. Additionally, the nickel content may be converted to nickel oxide. The iron content, sulfur content, and the like contained in the nickel-containing raw material 11 may be oxidized. Ore such as serpentine can be decomposed to form magnesium silicate such as MgSiO ₂ and further oxidized to MgO+SiO ₂ .

In the magnesium removing step 20 , water 21 is added to the oxidized roasted product 13 by a hydrating device 22 . As a result, magnesium oxide reacts with water to form magnesium hydroxide. A classifier 24 separates the magnesium content 26 from the residue 25 containing the nickel content in the mixture 23 that has passed through the hydrating device 22 . The method of removing the magnesium content 26 from the oxidized roasting product 13 may be a method of separating based on the difference in particle size as in the classifier 24, or may employ a specific gravity difference, solubility, or any other method. It is preferable to spray water in the hydrating device 22 while the oxidized roast product 13 is still hot, because MgO changes to Mg(OH) ₂ and is pulverized due to the effect of volume expansion. In this case, even if the nickel-containing raw material 11 before oxidizing roasting has a relatively large particle size, the residue 25 with a small particle size can be obtained. When the nickel-containing raw material 11 contains silica (SiO ₂ ) such as nickel ore, at least part of the silica may be separated and removed from the residue 25 together with the magnesium content 26 .

In this specification, the removal of the magnesium content 26 means that at least a part of the magnesium content 26 is removed from the oxidized roasting product 13, but when the residue 25 is used as the sulfated roasting object 31, It is preferable to remove as much of the magnesium content 26 as possible. If the sulfated roasting step 30 is performed while the magnesium content 26 remains in the sulfated roasting object 31, in addition to the excessive consumption of sulfur, magnesium sulfate is mixed in the sulfated roasting product 33, resulting in sulfuric acid. Separation problems between nickel and magnesium sulphate may arise.

The residue 25 of the classifier 24 obtained by removing the magnesium content 26 from the oxidized roasting product 13 is supplied to the sulfated roasting furnace 32 as the object 31 to be sulfated roasted. Examples of the sulfated roasting furnace 32 include a stirring roasting furnace, a rotary furnace roasting furnace, and a fluidized bed roasting furnace having a fluidized bed. As described above, when a fluidized bed roasting furnace is employed, the size of the device can be reduced. The sulfating roasting furnace 32 may be a roasting furnace different from the oxidizing roasting furnace 12, but the oxidizing roasting step 10 and the sulfonating roasting step 30 may be performed in the same roasting furnace. The structure of the sulfated roasting furnace 32 is not particularly limited, but the inlet for the object to be sulfated roasted 31 and the outlet for the sulfated roasted product 33 may be provided on the side surface of the furnace body, for example, in an oblique direction. An outlet for exhaust gas 34 may be provided in the upper portion of the furnace body. If the particle size of the residue 25 is small, the sulfonation roasting reaction starts from the surface of the object 31 to be sulfonation roasting, which shortens the reaction time, which is preferable.

The sulfated roasting furnace 32 treats the object to be sulfated roasted 31 by sulfated roasting to convert nickel contained in the nickel-containing raw material 11 into nickel sulfate. The sulfated roasting furnace 32 may be supplied with a sulfur content lacking in the object to be sulfated roasted 31, oxygen for oxidizing the sulfur content, or the like. In FIG. 1, for the sake of simplification, the supply routes of the various materials supplied to the sulfation roasting furnace 32 are not distinguished. Along with the object 31 to be sulfated roasted, an auxiliary substance or material may be supplied to the sulfated roaster 32 for the purpose of improving conversion efficiency of the sulfated roasting.

For example, a material harder than nickel contained in the object 31 to be sulfated roasted may be supplied to the sulfated roasting furnace 32 as media. As a result, the reactivity due to abrasion of nickel can be improved. When the object 31 to be sulfated roasted contains silica, the silica may also function as a medium. The material of the media is preferably softer than the inner wall material of the sulfate roasting furnace 32 . As a result, deterioration, damage, etc. of the inner wall material can be reduced. Specific examples of media include aluminum oxide such as synthetic alumina, zirconia, silica, silicon nitride, silicon carbide, tungsten carbide, and glass. The particle shape of the media is not particularly limited, but may be spherical, cylindrical, polyhedral, or the like. The average particle size of media is, for example, 0.02 to 10 mm. If the sulfated roast product 33 is water-soluble, the media can be separated according to water solubility, so it is preferable that the media be insoluble or sparingly soluble in water.

The sulfated torrefaction step 30 yields a sulfated torrefaction product 33 comprising nickel sulfate compounds. In the extraction step 40, water is supplied to the sulfated roasted product 33 in the dissolution tank 43, and a nickel sulfate solution 44 is obtained by a water dissolution step of dissolving the nickel sulfate compound in water. Although details will be described later, it is preferable to cool the sulfated roasted product 33 in the cooling unit 41 before adding water to the sulfated roasted product 33 . Alternatively, the sulfated roast product 33 may be pulverized before water is added to the sulfated roast product 33 . Since the iron contained in the sulfated roasting product 33 is poorly soluble in water, such as iron oxide and iron sulfide, a solid-phase residue 45 precipitates in the dissolving tank 43 . Therefore, from the dissolving tank 43, a nickel sulfate solution 44 is obtained as a liquid phase, and a residue 45 containing iron oxide as a solid phase is separated. Further, if necessary, a nickel sulfate compound from which impurities such as cobalt are removed can be obtained by performing a purification step of the nickel sulfate solution 44 in order to separate, for example, nickel sulfate and cobalt sulfate. The separation of the iron contained in the sulfated roasting product 33 is not limited to the method based on the difference in solubility, but the method based on the difference in magnetism, specific gravity, particle size, etc., or two or more of these methods. good too.

In the sulfated roasting of nickel-containing raw materials, the oxygen partial pressure and the sulfur dioxide partial pressure are thermodynamically more stable than nickel oxide in the Ni—S—O system, and the Fe—S—O system It is preferable to set conditions in which iron oxide is more thermodynamically 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 consumption of sulfur by iron is suppressed. , can improve the production efficiency of nickel sulfate.

FIG. 2 is an example of a conceptual phase diagram of Ni--S--O system and Fe--S--O system. The boundary line of each phase in the Ni—S—O system is indicated by a dashed line (-----), and the boundary line of each phase in the Fe—S—O system is indicated by a dashed-dotted line (----). . The chemical formulas attached to the arrows indicate the thermodynamically stable phases on the side of the respective boundary towards the arrows. The horizontal axis of the state diagram shown in FIG. 2 indicates the logarithm of the O ₂ partial pressure, with the O ₂ partial pressure increasing toward the right side and the O ₂ partial pressure decreasing toward the left side. The vertical axis of the state diagram shown in FIG. 2 indicates the logarithm of the SO ₂ partial pressure, the higher the SO ₂ partial pressure, and the lower the lower the SO ₂ partial pressure. The unit of partial pressure is atmospheric pressure (atm=101325 Pa), for example.

Examples of nickel sulfate contained in the Ni—S—O system include NiSO ₄ , and examples of nickel oxide include NiO. In the phase diagram shown in FIG. 2, the boundary line L _Ni indicates the boundary line between the thermodynamically stable region of nickel sulfate and the thermodynamically stable region of nickel oxide. 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 becomes 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 _Ni , nickel oxide becomes a thermodynamically stable phase.

Examples of iron sulfate contained in the Fe—SO system include FeSO ₄ and Fe ₂ (SO ₄ ) ₃ , and examples of iron oxide include Fe ₂ O ₃ . In the phase diagram shown in FIG. 2, the boundary L _Fe indicates the boundary between the thermodynamically stable region of iron sulfate and the thermodynamically stable region of iron oxide. 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 becomes a thermodynamically stable phase. In addition, 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 phase diagram shown in FIG. ₂ , in region A where the SO2 partial pressure and _O2 partial pressure are lower than the boundary line L _Fe and the SO2 partial pressure and _O2 partial pressure are higher _than the boundary line L _Ni , Ni Nickel sulfate in the -SO system and iron oxide in the Fe-S-O system are thermodynamically stable phases. Therefore, by roasting a system containing nickel (Ni), oxygen (O), and sulfur (S) under the conditions of this overlapping region A, iron sulfate is not generated even if iron is present in the system. The nickel content can be converted to nickel sulfate while being suppressed.

The roasting temperature (sulfated roasting temperature) in the sulfated 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 sulphated roasting temperature include 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or temperature ranges around or between these. At such a roasting temperature, the reduction of iron is suppressed, and the iron can coexist with the nickel sulfate compound in the form of iron oxide, iron sulfide, or the like. Post-process processing can be facilitated. In addition, at these temperatures, the carbonate is decomposed, so even if the carbonate is mixed, it is possible to prevent the carbonate from dissolving in water and remaining as an impurity. can facilitate the processing of
Furthermore, the sulfidation roasting temperature is preferably 600 to 700°C. At this temperature, even if the roasting target contains manganese (Mn) as an impurity derived from the nickel-containing raw material, manganese forms a spinel structure with iron, thereby removing manganese as an insoluble matter. easier to do.

As the O ₂ partial pressure in the sulfated roasting process, the common logarithm log p (O ₂ ) of the O ₂ partial pressure in units of atmospheric pressure (atm) is preferably in the range of -4 to -6. More preferably, p(O ₂ ) is in the range of −4 to −5, or log p(O ₂ ) is in the range of −5 to −6. By lowering 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 production of nickel sulfate can be promoted while suppressing the production of iron sulfate. This optimum region shifts slightly depending on the sulphated roasting temperature, and as the temperature increases, the log p(O ₂ ) in the overlap region A shifts toward greater (approaching zero (0)). Depending on the relationship between log p(SO ₂ ) and the sulphated roasting temperature, log p(O ₂ ) may be selected, for example, from the range of -8 to 0.

As the SO ₂ partial pressure in the sulfation roasting step, the common logarithm log p (SO ₂ ) of the SO ₂ partial pressure in units of atmospheric pressure (atm) is preferably in the range of -1 to +1, and log p (SO ₂ ) is - A range of 1 to 0 is more preferred. Even in the overlapping region A in FIG. ₂ , the formation of sulfate can be promoted by increasing the SO2 partial pressure. Furthermore, by setting the SO ₂ partial pressure to about normal pressure or less (the common logarithm of the partial pressure is approximately 0 or less), the total pressure of the roasting atmosphere in the sulfated roasting process does not become excessive, Equipment handling can be facilitated. Depending on its relationship to log p(O ₂ ) and the sulphated roasting temperature, log p(SO ₂ ) may be selected, for example, from the range of -4 to +1.

An inert gas such as nitrogen (N ₂ ) or argon (Ar) may be supplied to the roasting furnace to maintain a low O ₂ partial pressure in the roasting furnace. These inert gases can also be used as carriers when supplying volatile components such as gases and vapors to the roasting furnace. _The SO2 partial pressure can be adjusted, for example, by controlling the supply amount of the sulfur source. If the nickel-containing feedstock has a low sulfur content, the sulfur content may be fed to the sulfonated roasting step. Sulfur sources (sulfur sources) include solid sulfur (elementary sulfur, S) which is solid at room temperature, sulfur oxides (SO ₂ etc.), sulfuric acid (H ₂ SO ₄ ), sulfates, sulfides, Examples include sulfide ores such as pyrite (FeS ₂ ). When the sulfur source is sulfur (S), it is preferred to generate SO2 gas in an oxygen _- enriched state. Sulfur oxides may be produced by burning sulfur in an atmosphere containing oxygen.

A preferred partial pressure range can be determined from the position of the boundary line L _Ni and the boundary line L _Fe by examining the above-described phase diagram according to the sulfation roasting temperature. For example, when the sulfated roasting temperature is 650 to 750 ° C., the preferred partial pressure range is about -8 to -4 for log p (O ₂ ) and about -2 to +2 for log p (SO 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, and log p(SO ₂ ) is −4 to 0 degree is mentioned.

Next, the refining of nickel sulfate obtained by the sulfated roasting will be described in more detail. The water added to the sulfated roast products 33 and 42 in the dissolution tank 43 in the water dissolution step is preferably pure water treated so as not to contain impurities. Water treatment methods include, but are not limited to, one or more of filtration, membrane separation, ion exchange, distillation, disinfection, chemical treatment, adsorption, and the like. As water for dissolution, clean water obtained from a water source, industrial water, or the like may be used, or water obtained by treating waste water generated in another process may be used. Two or more types of water may be used. It is also possible to dissolve in not only pure water but also a sulfuric acid acid solution with a pH of about 4. For example, in a region where the pH of the solution is about 4 to 5, such as 3.8 to 5.5, and which is an oxidation region in oxidation-reduction potential measurement, while suppressing the dissolution of impurities such as other sulfates, nickel sulfate compounds is preferred because it is advantageous for selectively extracting into the aqueous phase.

The solubility of nickel sulfate in water is highest at 150 °C, 55 g NiSO ₄ in 100 g solution, but 22 g NiSO ₄ in 100 g solution even at 0 °C. Therefore, it is desirable to carry out the dissolving operation below the boiling point of water. In addition, the nickel sulfate solution 44 obtained in the water dissolution step preferably has a concentration at which NiSO ₄ is not precipitated even at room temperature, and when the concentration of NiSO ₄ is higher than that, it is preferable to maintain the nickel sulfate solution 44 in a heated state. . In order to adjust the temperature of the nickel sulfate solution 44, it is preferable to adjust the temperature of the sulfated roast products 33, 42 or the temperature of water before performing the melting operation. As at least part of the heat source for maintaining the nickel sulfate solution 44 in a heated state, residual heat of the sulfated roast products 33 and 42 may be used. Therefore, it is preferable to set the temperature of the sulfated roast products 33 and 42 before being dissolved in water to an appropriate temperature.

As described above, the system shown in FIG. The cooling unit 41 may be of a batch type or a continuous type. In the case of a batch system, the composition may be such that the sulfated roasting products 33 and 42 are left to stand until the temperature drops to a desired level without adding moisture. In the case of a continuous type, for example, a cooling unit 41 may be provided in a pipe connecting between the sulfated roasting furnace 32 and the dissolving tank 43 . In the cooling section 41, for example, a heat exchanger may be provided to recover excess residual heat from the sulfated roasted products 33 and 42, and the recovered residual heat may be used as various heat sources.

Depending on the state of the sulfated roasted products 33 and 42 obtained from the sulfated roasting furnace 32 or the state change during cooling in the cooling unit 41, the particles of the sulfated roasted products 33 and 42 are It may caking or form a poorly water-soluble film on the surface of the particles. Therefore, a step of pulverizing the sulfated roasted products 33, 42 may be added before water is added to the sulfated roasted products 33, 42. The means for pulverizing the sulfated roast products 33 and 42 is not particularly limited, but one or more of ball mills, rod mills, hammer mills, fluid energy mills, vibration mills, and the like can be used. The comminution of the sulfated torrefaction product 33,42 may begin prior to cooling the sulfated torrefaction product 33,42 or may begin after cooling the sulfated torrefaction product 33,42. .

After the water dissolution step, the method of solid-liquid separation is not particularly limited, and includes filtration, centrifugation, sedimentation, and the like. When a solid-liquid separation tank is installed separately from the dissolution tank 43, it is preferable to use a solid-liquid separation tank with high separation performance for solid-phase fine particles that become the residue 45. For example, a filtration tank, a centrifugation tank, One or more of sedimentation tanks and sedimentation tanks may be used. For example, in the filtration method, the method of filtration is not particularly limited, and examples thereof include gravity filtration, reduced pressure filtration, pressure filtration, centrifugal filtration, filter aid-added filtration, compression squeeze filtration, and the like. Pressure filtration is preferred because it allows easy adjustment of the differential pressure and enables rapid separation.

Impurities that can coexist with the nickel sulfate compound include iron (Fe), cobalt (Co), aluminum (Al), and the like. When these metal salts become sulfates in the roasting process, iron sulfate, cobalt sulfate, etc. are also dissolved when the nickel sulfate compound is dissolved in water. Furthermore, in water, for example, iron precipitates as oxides such as FeOOH, Fe ₂ O ₃ and Fe ₃ O ₄ , making it easier to remove impurities from the nickel sulfate compound. In the sulfated roasting step of the present embodiment, conditions are set so that the iron content is less likely to become iron sulfate, so a nickel sulfate solution 44 with a low iron content is obtained through water dissolution and solid-liquid separation. The residue 45 containing iron oxide and the like after the nickel sulfate solution 44 is separated can be reused as the iron content of cement. The iron oxide separated from the residue 45 can also be used as a raw material for ironmaking using a smelting reduction furnace, an electric furnace, or the like for the production of pig iron or the like, or for pigments, ferrite, magnetic materials, sintering materials, and the like. In particular, when nickel-containing raw materials are produced in remote areas far from industrial areas or cities, it is advantageous from the viewpoint of transportation costs to produce iron locally as well as nickel. be. For example, an electric furnace installed in the ferronickel smelting process is used to produce pig iron, and if the volume is reduced, it can be easily transported as iron ingots.

Among the impurities, metals with a lower ionization tendency than hydrogen (H), such as copper (Cu), gold (Au), silver (Ag), and platinum group metals (PGM), remain as solids in the water dissolution process. It can be removed by a liquid separation process. Solids removed by the solid-liquid separation step may contain compounds such as As, Pb, and Zn in addition to the impurities described above. Solids containing these impurities can be recycled as valuables.

The nickel sulfate solution 44 obtained through water dissolution and solid-liquid separation contains a nickel sulfate compound as the main component, so it can be transported and used as a solution of the nickel sulfate compound or as a solid nickel sulfate compound after drying or the like. be able to. Depending on the application, when it is desired to reduce, for example, cobalt sulfate as an impurity in the nickel sulfate solution 44, solvent extraction, electrodialysis, electrowinning, electrorefining, Techniques such as ion exchange and crystallization can be used.

In the case of solvent extraction, it is preferable to use an extractant capable of preferentially or selectively extracting cobalt over nickel into the solvent. This allows efficient purification, leaving the nickel sulfate compound in the aqueous solution. Examples of extractants include organic compounds having functional groups capable of bonding with metal ions, such as phosphinic acid groups and thiophosphinic acid groups. In solvent extraction, the diluent may be an organic solvent capable of separating the extractant from water. By dissolving the extractant bound with metal ions such as cobalt in the diluent, separation from the aqueous solution containing the nickel sulfate compound is facilitated without using large amounts of the extractant. The diluent is preferably an organic solvent that is poorly miscible 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 other substances, and the like. At this time, purification becomes possible by leaving at least part of the impurities in the liquid phase. Specific examples include evaporative crystallization and poor solvent crystallization. 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 used in the manufacture of pharmaceuticals and the like. For example, an organic solvent is added to a solution containing a nickel sulfate compound to precipitate the nickel sulfate compound. The organic solvent used for crystallization is preferably a water-miscible organic solvent, such as one or more selected from the group consisting of methanol, ethanol, propanol, isopropanol, butyl alcohol, ethylene glycol, and acetone. Two or more organic solvents may be used. Regarding the concentration range in which the organic solvent is miscible with water, it is preferable that the nickel sulfate compound is mixed at a concentration in which the organic solvent is added to the extent that the nickel sulfate compound is precipitated. The organic solvent added in the crystallization step is not limited to an anhydrous organic solvent, and may be a water-containing organic solvent to the extent that crystallization is not hindered. The ratio of water to the organic solvent is not particularly limited, but may be set in the range of, for example, 1:20 to 20:1, preferably about 1:1, for example, 1:2 to 2:1.

When a solid nickel sulfate compound is obtained through crystallization or the like, it is in the state of nickel sulfate anhydride, monohydrate, dihydrate, pentahydrate, hexahydrate, heptahydrate, etc. may The nickel sulfate compound precipitated by crystallization can be separated from the solution by solid-liquid separation. The solid-liquid separation method is not particularly limited, but includes filtration, centrifugation, sedimentation and the like. The metal dissolved in the solution is preferably neutralized and removed from the solution by a method such as precipitation. If the clarified solution is predominantly a mixture of water and organic solvent, the water and organic solvent can be separated by a method such as distillation.

According to the sulfated roasting method of the present embodiment, the following effects are obtained.
(1) The yield of the nickel sulfate compound can be improved by removing the magnesium content contained in the nickel-containing raw material.
(2) The conversion reaction from the nickel-containing raw material to nickel sulfate can be accelerated, and the reactivity is improved.
(3) High-purity nickel sulfate compounds can be produced from nickel-containing raw materials by sulfate roasting.
(4) It is possible to suppress the generation of iron sulfate in the sulfation roasting process. Moreover, generation of hydrogen (H ₂ ) gas can also be suppressed.
(5) In the sulfonated roasting product, the iron becomes a chemical species that is difficult to dissolve in water, and the nickel becomes a nickel sulfate compound that dissolves easily in water, making it easy to remove the iron.
(6) Equipment costs can be reduced compared to conventional methods.
(7) Since it can promote the conversion reaction of nickel-containing raw materials, for example, when iron is supplied in the form of iron oxide, iron oxide has the opportunity to form iron sulfate and form an iron-nickel ferrite alloy. The conversion reaction proceeds without giving an opportunity to do so. Therefore, a sulfated roast product containing high-purity nickel sulfate can be obtained.

Although the present invention has been described above based on preferred embodiments, 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 nickel-containing raw materials, but raw materials containing other metals (Cu, Zn, Co, Fe, etc.) other than nickel can also be considered. It is also possible to apply the roasting of the nickel-containing raw material according to the above-described embodiment to the roasting of raw materials containing other metals to obtain compounds of those metals.

The methods of treating nickel-containing feedstocks described above can also be used to process the oxidized roast product in processes other than sulfonated roasting.

EXAMPLES The present invention will be specifically described below with reference to Examples.

<Example 1>
Raw ore with a high magnesium content was pulverized using a tabletop ceramic ball mill to an average particle size of 150 μm. The mineral composition (weight ratio) of the raw ore used is as follows: Serpentine containing Mg and silica accounts for 82.89%, and magnetite containing Fe accounts for 9%. 0.06%, Mg-bearing Brucite 4.65%, Ni-bearing Heazlewood ore 2.92%, Ni-bearing pentlandite 0.19%, Mg-bearing callingite (coalingite) was 0.08%, chlorite containing Mg or the like was 0.07%, and olivine containing Mg or Fe was 0.04%. The total ratio of the minerals listed as the main components here is 99.88%. The proportion of serpentine is the sum of 82.25% Mg-Serpentine and 0.64% Fe-Serpentine.

A TG/DTA (thermogravimetric/differential thermal analysis) analyzer was used to collect the pyrolysis curve of serpentine from the pulverized raw ore. As a result, it was found that the samples were thermally decomposed at 600° C. to 650° C. although there were variations in the samples. Further, as a result of X-Ray analysis, the raw ore had a peak indicating the chemical formula of serpentine, Mg ₃ Si ₂ (OH) ₄ O ₅ , but this peak disappeared after oxidizing roasting. X-Ray detection peaks appeared in the portions showing the chemical formulas of Mg ₂ SiO ₄ and MgSiO ₃ . From this result, it was found that the oxidizing roasting temperature is desirable to be 650° C. or higher.

<Example 2>
A rubber tube electric furnace manufactured by Siliconit Co., Ltd. (furnace core tube: SUS316L, outer diameter 50 mm×400 mm length, maximum temperature 1500° C.) was installed so that the rubber tube was vertical, and a gas distribution plate was installed at the bottom. 1000 g of the same raw ore (containing Mg and Ni) as in Example 1 was pulverized to an average particle size of 2 mm and supplied to this roasting test apparatus, and fluidizing air was supplied from the bottom to maintain the fluidized state. At the same time, a gas absorption pipe and a vacuum pump were installed on the exhaust gas side. Oxygen was supplied to the green ore through a gas distribution plate. The oxidative roasting temperature of the green ore was set to 650°C. After oxidative roasting for 0.5 _hours , the oxidative roasting product was sprayed with water while it was at a _high temperature. was pulverized to a particle size of 150 μm to 0.8 mm. Analysis by X-Ray confirmed peaks indicative of Mg(OH) ₂ in the oxidized roast product. When the nickel content of the pulverized material obtained by this water spraying was concentrated by vibrating sieve and specific gravity separation, almost all Mg(OH) ₂ and SiO ₂ could be separated.

<Example 3>
Experiments were carried out to determine how many grams of various compounds dissolved in 100 ml of pure water at 25° C. were saturated. The results were 0.0086 g of magnesium oxide (MgO), 0.0012 g of magnesium hydroxide [Mg(OH) ₂ ], 25.5 g of magnesium sulfate (MgSO ₄ ), and 39.3 g of manganese sulfate (MnSO ₄ ). , nickel sulfate (NiSO ₄ ) was 65 g. From this result, it was speculated that it is easy to separate and remove magnesium oxide and magnesium hydroxide from nickel sulfate by solubility, but it is not easy to separate magnesium sulfate and manganese sulfate from nickel sulfate by solubility.

<Example 4>
Assuming that the nickel content is nickel sulfide ore (Ni ₃ S ₂ ), an equimolar amount of sulfur (S) was added to the nickel residue from which the Mg content and silica content were removed in Example 2. Using the same roasting test apparatus as that used for oxidizing roasting in Example 2, sulfate roasting was performed in an electric furnace at 650° C. for 30 minutes. The sulfated roasted product was dissolved in pure water to obtain a nickel sulfate solution. As a result of comparing the total amount of Ni in the raw ore before oxidation roasting and the total amount of Ni recovered as nickel sulfate solution after sulfate roasting and water dissolution, 98% of Ni was recovered.

INDUSTRIAL APPLICABILITY The present invention can be used to produce various nickel compounds used in electrical parts such as secondary batteries, chemical products, etc., or high-purity nickel sulfate compounds useful as raw materials for metallic nickel.

10 Oxidizing roasting step 11 Nickel-containing raw material 12 Oxidizing roasting furnace 13 Oxidizing roasting product 14 Exhaust gas 20 Magnesium removal step 21 Water 22 Hydrating device 23 Mixture 24 Classifier 25 Classifier residue 26 Magnesium content 30 Sulfated roasting process 31 Sulfated roasting object 32 Sulfated roasting furnace 33 Sulfurized roasting product Substances 34 Exhaust gas from sulfation roasting furnace 40 Extraction process 41 Cooling unit 42 Cooled sulfonation roasting product 43 Dissolving tank 44 Nickel sulfate solution 45 Dissolving apparatus residue.

Claims (5)

an oxidative roasting step of oxidizing and roasting a nickel-containing raw material containing a magnesium content and a nickel ore to convert the magnesium content into magnesium oxide ;
a magnesium removing step of removing the magnesium content from the nickel-containing raw material after the oxidizing roasting step;
A method for treating a nickel-containing raw material, comprising: 2. The method for treating a nickel-containing raw material according to claim 1 , further comprising a step of pulverizing the nickel-containing raw material before the oxidizing roasting step. 3. The method for treating a nickel-containing raw material according to claim 1 , wherein at least part of silica contained in said nickel ore is removed in said magnesium removing step. 4. A method for obtaining a roasted product containing nickel sulfate by sulfate roasting the nickel-containing raw material from which the magnesium content has been removed, after the magnesium removal step. 4. The method for treating a nickel-containing raw material according to any one of 1 to 3 . The nickel-containing raw material contains iron, and the sulfated roasting step makes nickel sulfate more thermodynamically stable than nickel oxide in the Ni—S—O system, and iron oxide in the Fe—S—O system. 5. The method of treating a nickel-containing raw material according to claim 4 , wherein the heat-roasting is performed under conditions of oxygen partial pressure and sulfur dioxide partial pressure that are thermodynamically more stable than iron sulfate.

Images