WO2020075288A1 - Method and device for processing nickel oxide ore - Google Patents

Abstract

A method for processing nickel oxide ore, the method having an oxidation roasting step for converting FeOOH included in nickel oxide ore to Fe₂O₃ or Fe₃O₄, and a sulfuric acid roasting step for heating and roasting the roasting product obtained in the oxidation roasting step under conditions of an oxygen partial pressure and a sulfur dioxide partial pressure at which nickel sulfate is more thermodynamically stable than nickel oxide in the Ni-S-O system, and iron oxide is more thermodynamically stable than iron sulfate in the Fe-S-O system, and generating a nickel sulfate compound.

Description

Nickel oxide ore processing method and processing apparatus

The present invention relates to a nickel oxide ore processing method and processing apparatus.

As nickel oxide ores, laterite ores such as limonite and saprolite produced from tropical or subtropical areas are known. Saprolite is in the process of producing clayey ores due to weathering of rocks, and is located on the rocks below the soil mainly consisting of mulch and limonite (limonite). In tropical regions, silica and base are leached during the weathering of rocks, and metal elements such as iron (Fe) and nickel (Ni) are concentrated in saprolite. Limonite forms when weathering progresses more than that of saprolite. Limonite has a higher Fe content and a lower Ni content than saprolite.

In Non-patent Document 1, as a method of utilizing nickel oxide ore, a method of producing ferro-nickel as a stainless steel raw material by subjecting saprolite to a dry smelting method and a hydrometallurgical method such as high pressure sulfuric acid leaching (HPAL) from limonite are used. A method for recovering nickel is described.

In recent years, not only saprolite having a high Ni content, but also limonite having a low Ni content is required to be used. However, conventionally, a hydrometallurgical method such as HPAL has been the mainstream of a limonite treatment method having a small iron content. There is a problem that even if limonite is treated by a dry smelting method like saprolite, it cannot be treated, or the Ni concentration of the ferronickel product does not increase, and the application range is limited to SUS200 or the like as a stainless steel raw material. When designing equipment for treating both limonite and saprolite, there is a problem that both hydrosmelting of limonite and dry smelting of saprolite are required, resulting in high cost.
Therefore, at present, saprolite having a high nickel content (for example, a nickel content of 1.8 wt% or more) has a lower nickel content (for example, a nickel content of about 1.6 wt% or 1. Saprolite (about 3 wt%) is used for the production of NPI (Nickel Pig Iron) having a low nickel concentration by the same method as the production of ferronickel described above. On the other hand, limonite having a low iron content and a nickel content of about 1.2 wt% is subjected to HPAL treatment, and limonite having a high iron content has a low nickel concentration (a nickel content of 8 wt% in a blast furnace). The actual situation is that NPI is manufactured (up to 3 wt%).

An object of the present invention is to provide a nickel oxide ore treatment method and a treatment device capable of treating various nickel oxide ores such as limonite and saprolite by a dry smelting method regardless of the content of nickel. That is.

According to a first aspect of the present invention, an oxidation roasting step of roasting a nickel oxide ore in an atmosphere containing oxygen and a roasting product obtained in the oxidation roasting step in a Ni—S—O system Heating under the conditions of oxygen partial pressure and sulfur dioxide partial pressure, which makes nickel sulfate thermodynamically more stable than nickel oxide, and iron oxide is more thermodynamically stable than iron sulfate in the Fe-SO system. And a roasting process of sulfuric acid for producing a nickel sulfate compound by roasting, and a method for treating a nickel oxide ore.

A second aspect of the present invention, the in the oxidation roasting step, said FeOOH contained in nickel oxide ore, a first aspect of the nickel oxide, characterized by converting the _Fe 2 _{O 3} or _Fe 3 _{O 4} It is a method of processing ore.

A third aspect of the present invention is the method for treating nickel oxide ore according to the first or second aspect, wherein the roasting temperature in the sulfuric acid roasting step is 600 ° C to 700 ° C.

In a fourth aspect of the present invention, the roasting furnace used in the oxidative roasting step is a rotary kiln, and the rotary kiln is used in a smelting step from the nickel oxide ore to ferro-nickel in combination with an electric furnace. The method for treating a nickel oxide ore according to any one of the first to third aspects is characterized in that it can be performed.

A fifth aspect of the present invention is the method for treating nickel oxide ore according to any one of the first to fourth aspects, wherein the nickel oxide ore contains limonite or saprolite.

A sixth aspect of the present invention is to provide an oxidation roasting furnace that roasts nickel oxide ore in an atmosphere containing oxygen, and a roasting product obtained in the oxidation roasting furnace in a Ni—S—O system. Heating under the conditions of oxygen partial pressure and sulfur dioxide partial pressure, which makes nickel sulfate thermodynamically more stable than nickel oxide, and iron oxide is more thermodynamically stable than iron sulfate in the Fe-SO system. It is a sulfuric acid roasting furnace which roasts and produces | generates a nickel sulfate compound, It is a processing apparatus of the nickel oxide ore characterized by the above-mentioned.

According to the first aspect, even when the nickel oxide ore contains iron, the nickel content is converted to a nickel sulfate compound, and the conversion of iron content to iron sulfate is suppressed. The consumption efficiency of nickel sulfate compound can be suppressed and the production efficiency of the nickel sulfate compound can be improved.

According to the second aspect, since the iron content contained in the nickel oxide ore is suppressed from being reduced to FeO in the oxidation roasting step, the heating temperature is low and the consumption of the reducing agent is small. Costs such as energy consumption can also be reduced compared to the operating conditions of the calcination furnace used to produce nickel.

According to the third aspect, the reduction of iron content is suppressed, and the iron content can coexist with the nickel sulfate compound in the state of iron oxide, iron sulfide, etc., so that the coagulation of particles in the roasted product is suppressed, and the post-process Can be easily processed. Even when the nickel oxide ore contains manganese, manganese forms a spinel structure with iron, so that manganese can be easily removed as an insoluble matter.

According to the fourth aspect, even when operating in an area producing nickel oxide ore, a facility for producing a nickel sulfate compound according to the nickel content of the ore, the demand for the product, the price, etc., It is possible to properly use equipment for producing ferronickel. By carrying out the production of nickel sulfate compound by the dry smelting method, the rotary kiln can be used in common for both the production of nickel sulfate compound and the production of ferronickel, thus reducing the investment cost for equipment. it can.

According to the fifth aspect, since nickel oxide ore that is relatively easy to procure can be used, productivity can be improved.

According to the sixth aspect, even when the nickel oxide ore contains iron, the nickel content is converted to a nickel sulfate compound, and the conversion of iron content to iron sulfate is suppressed. The consumption efficiency of nickel sulfate compound can be suppressed and the production efficiency of the nickel sulfate compound can be improved.

It is a block diagram which shows the outline of the processing method and processing apparatus of the nickel oxide ore by embodiment. It is a schematic diagram which shows an example of a roasting apparatus. FIG. 3 is a conceptual state diagram of Ni—S—O system and Fe—S—O system. It is a block diagram which illustrates the apparatus used in the Example.

The present invention will be described below based on preferred embodiments.

FIG. 1 is a configuration diagram showing an outline of a processing method and a processing apparatus for nickel oxide ore according to the present embodiment. In the treatment method of the present embodiment, for example, when the nickel sulfate compounds 32 and 42 are produced from the nickel oxide ore 12, the first heating step 10 performed using the first heating furnace 11 is an oxidation roasting step. When ferro-nickel 52 is produced from the nickel oxide ore 12, the first heating step 10 performed using the first heating furnace 11 is a calcination step.

When a nickel sulfate compound is produced from nickel oxide ore, the roasted product 13 obtained by oxidative roasting of nickel oxide ore is a sulfuric acid roasting step 20 (second heating step) performed using a second heating furnace 21. ). In the sulfuric acid roasting step 20, the nickel content contained in the roasted product 13 derived from the nickel oxide ore 12 is converted into a nickel sulfate compound by sulfation roasting. A sulfur source 23 may be added in the sulfuric acid roasting step 20. The roasted product 22 produced in the sulfuric acid roasting step 20 is added with water 34 in the water dissolving step 30 (water dissolving means 31) and then solid-liquid separated to obtain a solution containing the nickel sulfate compound 32 and iron oxide. And insoluble matter 33, etc. It is also possible to obtain the nickel sulfate compound 42 from which the impurities 43 have been removed by the purification step 40 (purification means 41) after the water dissolution step 30.
When ferro-nickel is produced from nickel oxide ore, the calcination product 14 obtained by calcination of the nickel oxide ore can be subjected to the smelting step 50 by providing it to a smelting furnace such as an electric furnace 51.

In the case of producing a nickel sulfate compound from nickel oxide ore, separate oxidation roasting steps (roasting devices) may be used for the oxidation roasting step and the sulfuric acid roasting step. Further, for example, as shown in FIG. 2, a roasting device 60 having a roasting furnace 61 in which a section 61A for performing the oxidation roasting step and a section 61B for performing the sulfuric acid roasting step are continuously provided is also used. Good. The roasting furnace 61 may be a rotary kiln. The roasting furnace 61 has an inlet 62 to which nickel oxide ore is supplied, a sulfur source supply unit 63 arranged in the middle of the roasting furnace 61, and an outlet 64 from which roasted products are discharged. An oxidation roasting process is performed between the inlet 62 and the sulfur source supply part 63, and a sulfuric acid roasting process is performed between the sulfur source supply part 63 and the outlet 64, thereby producing a roasting product containing a nickel sulfate compound. You can get things.

Examples of nickel oxide ores include laterite ores containing nickel such as limonite and saprolite. The limonite may be a low iron content limonite or a high iron content limonite, 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). Saprolite may be used (less than 1.8 wt%). It is also possible to add a raw material containing nickel components such as nickel oxide and nickel hydroxide to the nickel oxide ore supplied to the roasting furnace.

Prior to the oxidation roasting step, it is preferable to reduce the particle size of nickel oxide ore and other raw materials by operations such as shredding, crushing and abrasion. Since the reaction starts from the surface of the raw material in the roasting step, the smaller the particle size of the raw material, the shorter the reaction time, which is preferable. The crushing means is not particularly limited, but one or more kinds such as a ball mill, a rod mill, a hammer mill, a fluid energy mill and a vibration mill can be used. The particle size after pulverization is not particularly limited. In the case of a raw material that can be obtained in the form of fine particles, such as limonite ore, it may be directly supplied to the oxidation roasting step. When the raw material ore is supplied to the oxidation roasting step, it may be a dry powder or a slurry containing water. The apparatus for performing preliminary drying of the raw material ore is not particularly limited, and may be an apparatus that performs crushing and drying as a series of operations like a jaw crusher, or a drying apparatus such as a rotary dryer or an impact dryer may be used. it can. Since limonite ore has a large amount of fine powder, when using limonite ore, it is preferable to add an operation of recovering dust to a roasting furnace.

The oxidation roasting step is a step of roasting a nickel oxide ore in an oxidizing atmosphere containing oxygen (O ₂ ) such as air. In the oxidation roasting step, FeOOH contained in the nickel oxide ore is preferably converted into Fe ₂ O ₃ or Fe ₃ O ₄ in order to maintain the iron content of the iron oxide in the sulfuric acid roasting step described later. . The roasting temperature (oxidative roasting temperature) in the oxidative roasting step is, for example, 700 ° C. or lower, and specific examples include 500 ° C., 550 ° C., 600 ° C., 650 ° C., 700 ° C., or a temperature range before, after, or in the middle thereof. Is mentioned. The oxidation roasting temperature is preferably lower than the calcination temperature, as a temperature at which FeOOH, Fe ₂ O ₃ or Fe ₃ O ₄ is less likely to be thermally decomposed into FeO.
The heating temperature in the calcining step when smelting nickel oxide ore into ferro-nickel is, for example, 800 to 1100 ° C. as the temperature at which FeOOH, Fe ₂ O ₃ or Fe ₃ O ₄ is easily converted to FeO. By converting the iron oxide in the ore to FeO, it becomes easy to take out as FeO.SiO ₂ slag when performing the smelting process of ferronickel from the calcined product in an electric furnace or the like.

Since the oxidation roasting furnace can also be used as a calcining furnace in the conventional ferronickel smelting equipment, simply adding the equipment and the melting and refining equipment required for sulfuric acid roasting to this, A treatment method can be implemented. Ferro nickel production and nickel sulfate compound production can be selectively carried out in areas where nickel oxide ores are obtained.
For example, when using saprolite having a high Ni content as a raw material, ferronickel may be produced from saprolite. The Ni content contained in the saprolite used for the production of ferronickel is preferably 1.8 wt% or more on a dry basis excluding water. Examples of the Ni content of the above-mentioned saprolite include, but are not limited to, 1.8 wt%, 2.0 wt%, 2.5 wt%, and 3.0 wt%. When saprolite having a low Ni content (for example, Ni content of less than 1.8 wt%) or limonite is used as a raw material, the nickel sulfate compound may be produced through sulfuric acid roasting. Examples of the Ni content in saprolite or limonite having a low Ni content include, but are not limited to, 1.6 wt%, 1.5 wt%, 1.3 wt%, 1.0 wt% and the like. . In determining which of ferronickel and nickel sulfate compound should be produced, in addition to the Ni content of nickel oxide ore, the demand, price, production cost, etc. of the product ferronickel and nickel sulfate compound may be taken into consideration. . It is also possible to produce the nickel sulfate compound from the above-mentioned saprolite having a high Ni content.
When the calcination furnace is operated as an oxidative roasting furnace, as described above, the heating temperature is low and the reducing agent consumption is small so that the generation of FeO is suppressed. Costs such as energy consumption can also be reduced compared to the conditions.

The sulfuric acid roasting step is a step of producing a nickel sulfate compound by roasting the roasted product obtained in the oxidation roasting step with sulfuric acid. In the sulfuric acid roasting step, as shown in FIG. 3, the oxygen partial pressure and the sulfur dioxide partial pressure are such that nickel sulfate becomes thermodynamically more stable than nickel oxide in the Ni—S—O system, and Fe—S— The condition is that iron oxide is thermodynamically more stable than iron sulfate in the O system.

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

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

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

According to the state diagram shown in FIG. 3, SO ₂ partial pressure and the partial pressure of _{O 2} is lower than the boundary line _{L Fe,} and, SO ₂ partial pressure and the partial pressure of _{O 2} is in the higher region A than the boundary line _{L Ni,} Ni In the —SO system, nickel sulfate is a thermodynamically stable phase, and in the Fe—S—O system, iron oxide is a thermodynamically stable phase. Therefore, under the condition 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 (sulfuric acid roasting temperature) in the sulfuric acid roasting step is preferably in the range of 400 to 750 ° C, more preferably in the range of 550 to 750 ° C. Specific examples of the sulfuric acid roasting temperature include 400 ° C., 450 ° C., 500 ° C., 550 ° C., 600 ° C., 650 ° C., 700 ° C., 750 ° C., and the 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.
Furthermore, the sulfuric acid roasting temperature is preferably 600 to 700 ° C. At this temperature, even if the object of roasting with sulfuric acid, that is, the product of roasting with oxidation contains manganese (Mn) as an impurity derived from a raw material such as nickel oxide ore, manganese is spinel with iron. The formation of the structure facilitates removal of manganese as an insoluble matter.

The O ₂ partial pressure in the sulfuric acid roasting step is preferably such that the common logarithm of the O ₂ partial pressure in terms of atmospheric pressure (atm) log p (O ₂ ) is in the range of −4 to −6, and depending on the conditions, etc., log p _{(O 2)} is -4 to -5, or log p _{(O 2)} is more preferably in the range of -5 to -6. By decreasing the O ₂ partial pressure, the SO ₂ partial pressure tends to increase even in the overlapping region A of FIG. 3, so that the generation of nickel sulfate can be promoted while suppressing the generation of iron sulfate. This optimum region is slightly shifted depending on the sulfuric acid 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)).

As the SO ₂ partial pressure in the sulfuric acid 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 −1. The range of to 0 is more preferable. In the overlapping region A in FIG. 3, the SO ₂ partial pressure can be made higher to promote the production of sulfate. Furthermore, by setting the SO ₂ partial pressure to about normal pressure or less (the common logarithm of partial pressure is about 0 or less), the total pressure of the roasting atmosphere in the sulfuric acid roasting step does not become excessive, and the equipment Can be easily handled.

The roasting device for carrying out the sulfuric acid roasting step is not particularly limited, and examples thereof include a rotary kiln, a fluidized bed type heating furnace, a shelf type roasting furnace, a multi-stage roasting furnace, and various other roasting furnaces. In order to maintain the condition of low O ₂ partial pressure in the roasting device, an inert gas such as nitrogen (N ₂ ) or argon (Ar) may be supplied to the roasting device. These inert gases can also be used as a carrier when supplying volatile components such as gas and vapor to the roasting device. When the raw material such as nickel oxide ore has a low sulfur content, the sulfur content may be supplied to the sulfuric acid roasting step. The source of sulfur content (sulfur source) is not particularly limited, but solid sulfur (elementary sulfur, S), sulfur oxides (SO _2, etc.), sulfuric acid (H ₂ SO ₄ ), sulfate, sulfide, pyrite Examples include sulfide ores such as (FeS ₂ ). When the sulfur source is elemental sulfur, it is preferable to generate SO ₂ gas in an oxygen-enriched state.

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

The water added to the roasted product in the water dissolution step is preferably pure water that has been treated so as not to contain impurities. The water treatment method is not particularly limited and may be one or more of filtration, membrane separation, ion exchange, distillation, disinfection, chemical treatment, adsorption and the like. As the water for dissolution, tap water obtained from a water source, industrial water, or the like may be used, or water obtained by treating the 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 sulphate in water is highest at 150 ° C., 100 g of solution contains 55 g of NiSO _4, but even at 0 ° C. 100 g of solution contains 22 g of NiSO ₄ . Therefore, it is desirable to carry out the dissolving operation at a temperature below the boiling point of water. Further, it is preferable that the solution obtained in the water dissolving step has a concentration at which NiSO ₄ does not precipitate even at room temperature, and it is preferable that the solution having a higher concentration of NiSO ₄ maintains a heated state.

The solid-liquid separation method after the water dissolution step is not particularly limited, and examples thereof include a filtration method, a centrifugal separation method, and a sedimentation separation method. Desirably, it is preferable to use an apparatus having a high performance of separating fine particles contained in the solid phase. 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 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, etc., and impurities can be easily removed from the nickel sulfate compound. In the sulfuric acid roasting step of the present embodiment, conditions are set such that the iron content is unlikely to become iron sulfate, and therefore, a nickel sulfate compound having a low iron content can be obtained through water dissolution and solid-liquid separation. The residue containing iron oxide or the like after dissolving the nickel sulfate compound can be reused as the iron content of cement. Further, the iron-rich residue such as iron oxide can be used for producing pig iron or the like as an iron-making raw material using a smelting reduction furnace, an electric furnace or the like, or for pigments, ferrites, magnetic materials, sintered materials, etc. . In particular, when the area producing nickel oxide ore is a remote area away from industrial areas, cities, etc., it is advantageous from the viewpoint of transportation costs to commercialize iron as well as nickel in the field. is there. For example, if pig iron is produced using an electric furnace provided in the smelting process of ferronickel 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 are 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. Solids containing these impurities can also be recycled as valuable resources.

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

In the case of solvent extraction, it is preferable to use an extractant that can preferentially or selectively extract cobalt over nickel in 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 metal ions 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 immiscible 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 used in the production of pharmaceuticals and the like, for example, an organic solvent is added to a solution containing a nickel sulfate compound to precipitate a nickel sulfate compound. The organic solvent used for crystallization is preferably an organic solvent miscible with water, and examples thereof include at least one 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 nickel oxide ore processing method and the processing apparatus of the present embodiment, the following effects can be obtained.
(1) A high-purity nickel sulfate compound can be produced from nickel oxide ore by a combination of oxidation roasting and sulfuric acid roasting.
(2) The roasting furnace can also be used as a calcining furnace in the step of producing ferronickel from nickel oxide ore by dry smelting.
(3) Generation of iron sulfate can be suppressed in the sulfuric acid roasting step. Further, generation of hydrogen (H ₂ ) gas can also be suppressed.
(4) 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.
(5) The equipment cost can be reduced as compared with the conventional method, and the existing equipment can be used as a roasting furnace.

Although the present invention has been described above based on the 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.
For example, at the time of equipment design, it is possible to carry out layout design as equipment for manufacturing ordinary ferronickel and add design so that roasted products can be transferred from the outlet of the calcining furnace to the sulfuric acid roasting furnace. is there. For example, when only the nickel sulfate compound needs to be produced, the installation of the electric furnace for producing ferronickel may be omitted. On the contrary, when the demand for ferronickel is high, the electric furnace may be installed or the production of ferronickel may be started first, and the sulfuric acid roasting furnace or the production of the nickel sulfate compound may be started later. In this way, even when there is uncertainty about the market and demand for nickel products, both the nickel sulfate production facility using limonite oxide ore and the ferronickel production facility using saprolite oxide ore are treated by the dry process. As a result, it is possible to perform operations that can be consistently processed in the same area that produces nickel oxide ore, which is also advantageous from the viewpoint of avoiding investment risk.

(1) Nickel Oxide Ore Nickel limonite ore from Surigao Island, Philippines was used in the test described below. The analysis results of the mineral composition (wt%) are shown below.

Fe _{content: 41%, MgO: 16%} , SiO 2: 3%, Al 2 O 3: 2.7%, Cr content: 0.15%, Ni content: 1.2%, Co content: 0.05% , Other solid content: 5.9%, water content: 30%

Of the Fe content (41% of the ore), goethite: FeOOH accounted for 55%. MgO (16% of ore) was mainly montmorillonite: CaMg ₂ Si ₄ O ₁₀ (OH) ₂ . SiO ₂ (3% of ore) was mainly montmorillonite and the serpentine: (Mg, Fe) ₃ Si ₂ O ₅ (OH) ₄ . The sample ore also contained Ni content (1.2% of ore), Co content (0.05% of ore), etc., and had a water content of 30%.

(2) Test apparatus used for roasting test For the roasting test, the test apparatus 100 shown in FIG. 4 was used. A sample of nickel oxide ore is placed on the pan 101. The saucer 101 is set inside a glass container 102 installed in an electric furnace 103. The glass container 102 is provided with a thermometer 104 such as a thermocouple that can measure the ambient temperature, an injection pipe 105 that can inject various gases, and an outlet 106 for exhaust gas generated inside. The electric furnace 103 can raise the temperature to a desired temperature to heat the sample. In the injection pipe 105, dry air or SO ₂ gas containing nitrogen gas can be supplied as needed while constantly injecting argon gas. The exhaust gas discharged from the outlet 106 can be processed by the exhaust gas processing device 108 via the gas analyzer 107. Data of various gas amounts and analytical values can be collected by a computer (not shown).

(3) Oxidation and Roasting Step 10 g of nickel limonite ore was collected in a container, and the ore was dried at 110 ° C. for 2 hours to remove water. 5 g of dried ore was weighed on the saucer 101. The glass container 102 was set in the electric furnace 103, and the saucer 101 in which the ore was weighed was set in the glass container 102. The glass container 102 is provided with a thermometer 104 composed of a thermocouple capable of measuring the ambient temperature, an injection pipe 105 capable of injecting various gases, and a generated exhaust gas outlet 106, and heated to a specified temperature in the electric furnace 103. The sample was oxidatively roasted. The oxidation roasting temperature was 600 ° C and 700 ° C. During the oxidation roasting, Ar or air was appropriately supplied to the sample through the injection pipe 105 (SO ₂ was not supplied).

(4) Sulfuric acid roasting step Following the (3) oxidative roasting step, the sulfuric acid roasting step was performed under the following three conditions.
(Condition example 1) 50% concentrated sulfuric acid is added to the sample, and adjusted at a temperature of 600 ° C. so that log p (O ₂ ) is −4 and log p (SO ₂ ) is in the range of +1 to −1.
(Condition example 2) Sulfur was added to the sample and oxygen was added in a reaction-deficient manner so that the log p (O ₂ ) was -4 and the log p (SO ₂ ) was in the range of +1 to -1 at a temperature of 600 ° C. Adjust to.
(Condition example 3) Sulfur was added to the sample and oxygen was added in a reaction-deficient manner so that the log p (O ₂ ) was -4 and the log p (SO ₂ ) was in the range of +1 to -1 at a temperature of 700 ° C. Adjust to.

(5) Water Dissolving Step Each of the three types of samples that had been subjected to the above (3) oxidation roasting step and (4) sulfuric acid roasting step was stirred with 50 g of pure water for 1 hour. The solid content of the stirred slurry was filtered with a Millipore filter separator. The filtrate that passed through Millipore was subjected to atomic absorption spectrometry, and the concentrations of nickel (Ni), iron (Fe), and manganese (Mn) were measured. From this measurement result, the proportion (dissolution rate) dissolved in pure water was determined with the amount contained in the sample used for roasting being 100 wt%. For example, the dissolution rate of Ni means the ratio of Ni dissolved in pure water to Ni contained in the roasted product. The results of calculating the dissolution rate (wt%) are shown below. The number of the condition example corresponds to each condition example shown in the above (4) sulfuric acid roasting step.

(Condition example 1) Ni dissolution rate: 89%, Fe dissolution rate: 1%, Mn dissolution rate: 75%
(Condition example 2) Ni dissolution rate: 86%, Fe dissolution rate: 1%, Mn dissolution rate: 74%
(Condition example 3) Ni dissolution rate: 86%, Fe dissolution rate: 1%, Mn dissolution rate: 2%

From the calculation results of the dissolution rate, when sulfuric acid roasting is performed at 600 ° C. or higher (particularly higher than 600 ° C.), manganese forms a spinel structure with iron in the reaction of Fe ₂ O ₃ + MnO → MnFe ₂ O ₄ , It was found that Mn becomes difficult to dissolve in water. It is known that when the sulfuric acid roasting temperature is 700 ° C. or higher (particularly higher than 700 ° C.), the decomposition of the sulfate occurs, so it is considered preferable that the sulfuric acid roasting temperature is 600 ° C. to 700 ° C. .

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 ... 1st heating process (oxidation roasting process or calcination process), 12 ... Nickel oxide ore, 20 ... Sulfuric acid roasting process, 30 ... Water dissolution process, 32 ... Nickel sulfate compound, 40 ... Purification process, 42 ... Purification Nickel sulfate compound, 50 ... smelting process, 51 ... electric furnace, 52 ... ferronickel, 60 ... roasting device, 61 ... roasting furnace, 61A ... section for performing oxidation roasting process, 61B ... sulfuric acid roasting process Compartment to do.

Claims (6)

1. An oxidation roasting step of roasting nickel oxide ore in an atmosphere containing oxygen,
   In the roasting product obtained in the oxidation roasting step, nickel sulfate is more thermodynamically stable than nickel oxide in the Ni—S—O system, and iron oxide is iron sulfate in the Fe—S—O system. A sulfuric acid roasting step of producing a nickel sulfate compound by heating and roasting under conditions of oxygen partial pressure and sulfur dioxide partial pressure that are more thermodynamically stable than
   A method for treating nickel oxide ore, which comprises:
2. The method for treating nickel oxide ore according to claim 1, wherein FeOOH contained in the nickel oxide ore is converted to Fe ₂ O ₃ or Fe ₃ O ₄ in the oxidation roasting step.
3. The method for treating nickel oxide ore according to claim 1 or 2, wherein the roasting temperature in the sulfuric acid roasting step is 600 ° C to 700 ° C.
4. The roasting furnace used in the oxidation roasting step is a rotary kiln,
   The rotary kiln can be used in a smelting process from the nickel oxide ore to ferro-nickel by combining with an electric furnace, wherein the nickel oxide ore according to any one of claims 1 to 3 is used. Processing method.
5. The method for treating nickel oxide ore according to any one of claims 1 to 4, wherein the nickel oxide ore contains limonite or saprolite.
6. An oxidation roasting furnace that roasts nickel oxide ore in an atmosphere containing oxygen,
   In the Ni—S—O system, nickel sulfate is thermodynamically more stable than nickel oxide in the roasting product obtained in the oxidation roasting furnace, and in the Fe—S—O system, iron oxide is iron sulfate. And a sulfuric acid roasting furnace that produces a nickel sulfate compound by heating and roasting under conditions of oxygen partial pressure and sulfur dioxide partial pressure that are more thermodynamically stable than
   An apparatus for treating nickel oxide ore, comprising:

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