KR101172897B1 - Method for recovering nickel from nickel containing raw material - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively recovering nickel from a nickel-containing raw material, wherein a reducing gas containing at least twice the number of moles of hydrogen relative to the (Fe + Ni) mole of the nickel-containing raw material is used at a temperature of 550-950 ° C. Reducing the nickel-containing raw material at a temperature; A slurrying step of slurrying the reduced nickel-containing raw material; Leaching step of leaching nickel by dissolving the nickel-containing raw material by adding a slurry-containing raw material and acid to the reactor in an oxygen-free state; A solid-liquid separation step of filtering and removing the residue sludge from the solution obtained by the leaching step by a solid-liquid separator; And an iron removing step of removing iron from the nickel-containing solution.
According to the present invention, nickel recovery can be performed at a relatively low temperature (25-80 ° C.) and atmospheric pressure, which can be applied to materials of general installations, high-speed acid leaching, stable and effective recovery, and In addition, it is economical to reduce the amount of hydrogen used in recovering nickel.

Description

How to recover nickel from nickel-containing raw materials {METHOD FOR RECOVERING NICKEL FROM NICKEL CONTAINING RAW MATERIAL}

The present invention relates to a method for effectively recovering nickel from a raw material containing nickel, and more particularly, to a method for effectively acid leaching and recovering nickel from a nickel ore having a high metal content.

Nickel-containing ores include ore such as limonite and saprolite, and these ores have passivation properties, so they are acid resistant and slow to dissolve. Therefore, as a method for effectively leaching nickel, methods for recovering nickel by dissolution in an autoclave under high temperature and high pressure have been proposed, which is called 'HPAL (High Pressure Acid Leaching)'.

Nickel leaching at room temperature does not exceed 85% nickel recovery even after leaching for several months or more.However, HPAL method can be used for leaching more than 90% nickel within 2 hours. Can be.

As a technique for recovering nickel by the HPAL method, Korean Unexamined Patent Publication No. 2007-7020915, Japanese Unexamined Patent Publication No. 2010-031341 and the like can be given. However, HPAL method should be carried out under the high temperature and high pressure of the autoclave, and it is known that only titanium material can be used mainly because of its strong acidity, and thus has the disadvantage of high facility cost and high maintenance cost.

On the other hand, the present inventors have proposed a method for recovering nickel by acid leaching after the hydrogen reduction of the nickel-containing raw material in Korea Patent Publication No. 2009-0031321. The technique of the patent document, the step of recovering V, Mo in the petrochemical desulfurization waste catalyst and treating the remaining residue with an acid to remove alkali elements in the residue; Drying the residue from which the alkaline elements have been removed, and then heat-treating at a temperature range of 600-1300 ° C. in a reducing atmosphere to reduce Ni and Fe present in the form of oxides in the residue with a metal; Leaching the reduction product obtained in the step with an acid to selectively dissolve iron and nickel; Filtering the solution to obtain a leached nickel and iron ion containing solution; Neutralizing the solution containing Ni and Fe ions with alkali to form Fe, Ni hydroxide; Disclosed is a method for producing an iron nickel-containing raw material from a petrochemical desulfurization waste catalyst recycling residue comprising the step of filtering and drying the product obtained in the above step to obtain Fe and Ni-containing raw materials.

However, in the case of recovering Ni from Ni ore by applying the above method, a large amount of hydrogen is required, which greatly affects economic efficiency. That is, the waste catalyst residue usually contains reduced metal (Fe + Ni) in a content of 15% by weight or less, but in the case of nickel ore, the content of metal (Fe + Ni) is 15-65% by weight, which is very high. You must do it.

Therefore, in recovering Ni from Ni ore, minimization of the use of hydrogen is required, and development of a more economical Ni recovery method is required.

In addition, since nickel ore contains a large amount of iron, extraction of a sample after reduction has a problem in that iron is oxidized while reacting with oxygen in air to ensure safety.

The present invention provides a more improved method for recovering nickel compared to the conventional method in which Ni recovery can be performed at a relatively low temperature (25-80 ° C.) and atmospheric pressure, which can be applied to materials of general equipment, and high-speed acid leaching is possible. To provide.

Furthermore, the present invention is to provide a method for effectively solving the stability problem due to oxidation during sampling after reduction caused by the high iron content of nickel oxide ore.

The present invention seeks to provide a method of recycling hydrogen to minimize the use of hydrogen in recovering Ni.

The present invention relates to a method for recovering nickel from a nickel-containing raw material, the nickel at a temperature of 550-950 ℃ using a reducing gas containing at least two times the number of moles of hydrogen relative to the (Fe + Ni) mole of the nickel-containing raw material A reducing step of reducing the containing raw material; A slurrying step of slurrying the reduced nickel-containing raw material; Leaching step of leaching nickel by dissolving the nickel-containing raw material by adding a slurry-containing raw material and acid to the reactor in an oxygen-free state; A solid-liquid separation step of filtering and removing the residue sludge from the solution obtained by the leaching step by a solid-liquid separator; And an iron removing step of removing iron from the nickel-containing solution.

The nickel-containing raw material may be dust obtained in the process of dry smelting nickel ore, or nickel ore, when the nickel-containing raw material is nickel ore, the nickel ore is dried, ground to a particle size of 1 mm or less, and What is obtained by baking at 250-850 degreeC can be used.

In addition, the reducing gas containing hydrogen may be a gas containing only hydrogen or a mixed gas of nitrogen and hydrogen.

On the other hand, the slurrying step is preferably carried out by immersing the reduced nickel-containing raw material in a tank containing oxygen-blocked water.

In addition, the acid may be sulfuric acid or hydrochloric acid, and in the case of sulfuric acid, at least one mole of the number of moles of (Fe + Ni) of the nickel-containing raw material is added, and in the case of hydrochloric acid, twice the number of moles of (Fe + Ni) are added. It is desirable to.

The leaching step is preferably stopped when the pH of the solution is in the range of 0.1-1.0, it is preferably carried out for 0.5 to 2 hours at a reaction temperature of 25-80 ℃.

In addition, the iron removing step may be performed by blowing the oxygen-containing gas to adjust the pH of the nickel-containing solution in the range of 2.5-5.5 to produce iron hydroxide, filtering the generated iron hydroxide, or by solvent extraction.

Furthermore, it is preferable to collect hydrogen from the exhaust gas discharged from the reduction step and re-supply it to the reduction step. The collection of hydrogen from the exhaust gas may be done by cooling the exhaust gas containing water vapor and hydrogen to remove dust containing water produced by the condensation of the water vapor.

In addition, the hydrogen generated in the leaching step may be collected and re-supplied to the reduction step, using a scrubber from the exhaust gas containing hydrochloric acid mist and hydrogen discharged in the leaching step to remove the dust containing hydrochloric acid mist, Hydrogen can be resupplied to the reduction step by capture.

According to the present invention, in recovering Ni, unlike in the prior art, it is not necessary to perform Ni at a high temperature and high pressure in order to leach nickel from a nickel-containing raw material, so that high-speed acid leaching is possible at low temperature and normal pressure, and thus the reactor is maintained at high temperature and high pressure. There is no need to use expensive titanium to withstand it.

In addition, it is possible to stably and effectively recover Ni from nickel ore, so that it can be suitably applied to nickel nickel smelting.

Furthermore, according to the present invention, the amount of hydrogen used in recovering Ni from nickel ore can be reduced and economical.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively recovering nickel from a nickel-containing raw material, and in particular, to a method for recovering nickel by effectively acid leaching nickel from a nickel ore having a high metal content.

The nickel ore to which the present invention is applied is not particularly limited as long as it contains nickel, and examples thereof include ore such as limonite and sapolite. In order to recover nickel from the nickel ore, it is preferable to undergo a pretreatment of drying, grinding and firing. Hereinafter, the drying, grinding, and firing steps, which are pretreatment steps, will be described in detail.

In general, when nickel is recovered from nickel-containing ore, it has been leached by the wet method, and for this purpose, it is usually pulverized in a state containing water. However, in the present invention, since there is a subsequent heat treatment step, it is preferable to go through a drying step to remove the pre-moisture. Dry grinding after the drying step may improve the grinding efficiency more than the wet grinding process. Furthermore, when it is necessary to uniformly control the ore particle size required for the reduction and leaching reactions, it is possible to easily classify the particles by particle size using the wind speed of the dust collector, so that the uniform particle size required for the reduction and leaching reactions can be achieved. It is possible to obtain a powder having

In the present invention, it is preferable to use an ore powder having a particle size of 1 mm or less. When the particle size of the ore powder is larger than 1 mm, the reduction / leaching rate is slow, and in particular, the acid and leaching reactions are not preferable because of large clogging of the pump and pipes and poor workability. If the particle size of the powder is 1 mm or less, the lower limit thereof is not particularly limited, but in order to obtain a powder having a particle size smaller than 10 μm, the grinding process must be performed for a long time or more than several times. It is more preferable to do.

In general, nickel ore contains crystal water, and if it is not subjected to calcination, crystal water contained in the ore is released as water in a subsequent reduction process to slow down the reduction reaction, and therefore, it is preferable to undergo a calcination process. Among nickel ores, limonite emits crystal water at about 250-350 ° C and sapprite at around 650-750 ° C. Therefore, the ore powder obtained in the grinding process is in the range of 250-850 ° C. It is preferable to remove the crystal water contained in nickel ore by baking.

On the other hand, saprolite having a high nickel content is mainly used as a raw material for dry smelting, and nickel can be recovered by applying the present invention to rotary kiln dust generated in the dry smelting process. However, since the dust is included in a range suitable for applying the present invention and exposed to high temperature during the dry smelting process, the grinding and calcining process as in nickel-containing ore is not required. However, if the particle size is out of the range required by the present invention, for example, because the dust is exposed to air and contains moisture, it may be subjected to a pulverization or firing treatment as necessary.

Nickel ore is different depending on the type of ore, but usually contains 1-2.5% by weight of Ni and 15-55% by weight of Fe. Nickel can be recovered by reducing nickel from such a nickel ore.

In order to recover such a nickel-containing raw material, the reduction is performed using a reducing gas.

Hydrogen is preferably used as the reducing gas used in reducing nickel. By using hydrogen as the reducing gas in this way, excess hydrogen in the reduction reaction and hydrogen generated in the leaching reaction can be recovered and reused, thereby reducing the cost associated with the use of the reducing gas.

In reducing the nickel-containing raw material using hydrogen as the reducing gas, the theoretical reaction is expressed by the following equation (1).

(NiFe) OFe ₂ O _{3 ,} + 4H ₂ = (NiFe) + 2Fe + 4H ₂ O (1)

However, in actual reduction reaction, more than twice as much hydrogen is required, and this is expressed by the following equation (2).

(NiFe) OFe ₂ O _{3 ,} + 8H ₂ = (NiFe) + 2Fe + 4H ₂ O + 4H ₂ (2)

As described above, in recovering the nickel-containing raw material using hydrogen as the reducing gas, it is preferable to use a reducing gas containing two or more moles of hydrogen relative to the number of moles of (Fe + Ni) contained in the nickel-containing raw material. . At this time, the temperature of the reduction furnace is preferably in the range of 550-950 ℃. This is because the reduction rate does not sufficiently occur at the reduction temperature of 550 ° C. or lower, and the recovery rate is lowered at subsequent leaching.

Meanwhile, an inert gas may be used together to remove oxygen other than hydrogen present in the reduction furnace during the reduction reaction, and the inert gas may include nitrogen and the like, and such an inert gas may be recovered and reused.

In reducing and recovering nickel from a nickel-containing raw material, a large amount of hydrogen is required as described above, and thus a problem of increasing costs due to hydrogen occurs, and thus, it is necessary to solve such a problem. Therefore, it is preferable to recycle excess hydrogen obtained after the reaction.

Excess hydrogen and water vapor are generated by the reduction reaction as in Equation (2), which requires separation of water vapor and hydrogen to recycle hydrogen. Separation of water vapor and hydrogen can be separated from excess hydrogen by cooling the exhaust gas discharged after the reaction to change the water vapor into water. That is, when the exhaust gas is cooled, water vapor condenses to become water, whereby it can be separated and recovered from hydrogen through separation and recovery of gas and liquid.

On the other hand, since the reduced nickel-containing raw material obtained in the reduction process is dust having a particle size of 1 mm or less, these must be separated from the exhaust gas. Therefore, it is necessary to separate both the liquid water and the hydrogen gas and the solid dust. For this purpose, a scrubber can be used. When the exhaust gas is cooled in the scrubber, dust and water vapor are discharged to the lower part, hydrogen is discharged to the upper part, and hydrogen can be recovered by separating and collecting the compressed hydrogen gas and compressing the recovered hydrogen gas. It can be reloaded into the furnace.

On the other hand, if the nickel ore is reduced, the iron component is very high, the reoxidation occurs when extraction into the air after reduction. In this reification, the heat generation accelerates the oxidation reaction, which poses a fire hazard. Therefore, the reduced nickel-containing raw material may be discharged into a tank containing oxygen-blocked water to slurry the reduced nickel-containing raw material to prevent oxidation of the iron component.

The slurry obtained is transferred to a pump and subjected to a subsequent leaching step. In the leaching step, the slurried nickel-containing raw material is introduced into an oxygen-free reactor, and acid is added to dissolve the nickel by dissolving the nickel-containing raw material.

The acid used in the leaching step is not limited thereto, and hydrochloric acid, sulfuric acid and nitric acid, as well as various other acids may be used. However, it is more preferable to use hydrochloric acid and sulfuric acid in terms of wastewater treatment and cost.

When the reduced nickel-containing raw material is leached using an acid of sulfuric acid and hydrochloric acid, metal acid reactions such as the following formulas (3) and (4) proceed to generate hydrogen gas.

(NiFe) + 2Fe + 6HCl → (NiFe) Cl ₂ + 2FeCl ₂ + 3H ₂ (3)

(NiFe) + 2Fe + 3H ₂ SO ₄ → (NiFe) SO ₄ + 2FeSO ₄ + 3H ₂ (4)

Therefore, as can be seen from the above formulas (3) and (4), sulfuric acid in the acid should be added at a mole number of one or more times the number of moles of (Fe + Ni) of the nickel-containing raw material, and hydrochloric acid is (Fe + Ni). The equivalence ratio can be reached by adding twice the number of moles.

On the other hand, when the reduced nickel-containing raw material is leached with an acid, nickel and iron are selectively dissolved as ions by the reactions of the formulas (3) and (4), and Al ₂ O ₃ and SiO ₂ contained in the nickel-containing raw material , Cr ₂ O ₃ and the like hardly occur due to acid dissolution and are obtained as a solid residue. Therefore, the nickel-containing solution obtained by the leaching step and the residue of the solid phase are very easy to be separated by filtration, so that the nickel-containing solution can be separated by a solid-liquid separator such as a filter press or a decanter.

The leaching step may be carried out at a temperature of 25-80 ℃. Leaching of nickel by acid can be completed within 2 hours even if the present invention is applied at room temperature. The leaching step is faster as the reaction temperature is higher, but the energy cost is higher as the reaction temperature is higher, especially when the leaching reaction is carried out at 80 ℃ or more, the generation of hydrogen gas exploded, it is difficult to control the pressure of hydrogen Hydrogen recovery and reuse becomes difficult. Therefore, it is preferable to carry out the leaching reaction in the above temperature range.

Termination of the leaching reaction can be confirmed by changing the pH. When the free acid is removed by the leaching reaction, the pH of the solution in the reactor rises. It is preferable to terminate the leaching reaction when the pH is in the range of 0.1-1. If the pH is lower than 0.1, free acid must be removed in a subsequent process, which increases the alkali consumption. In addition, when the pH is higher than 1 because hydrochloric acid is less than the equivalent ratio, substitution substitution of Ni occurs by the unreacted Fe metal, resulting in a problem that the nickel recovery rate decreases. Therefore, when the pH of the solution in the reactor reaches the range of 0.1-1, the leaching reaction is terminated and filtered to separate the solution containing nickel ions and the residue sludge.

When the leaching step is performed in the same manner as above, leaching is terminated within 2 hours. At this time, 90% or more nickel leaching rate can be secured. More preferably, if the leaching step is performed in less than 30 minutes, since the nickel is not sufficiently leached from the nickel-containing raw material, the leaching step is preferably performed for 30 minutes or more.

Hydrogen used in the reaction of formula (1) is generated in the leaching step as shown in formulas (3) and (4). Therefore, the hydrogen demand can be greatly reduced by recovering and reusing hydrogen generated in the formulas (3) and (4). The recovery of the hydrogen may be recovered by removing the dust containing hydrochloric acid mist using a scrubber from the exhaust gas containing hydrochloric acid mist and hydrogen discharged in the leaching step, by collecting the hydrogen, the recovered hydrogen is reduced Can be reused by resupplying

Hydrogen generated in the leaching step was recovered according to the method of the present invention and the hydrogen generation amount and recovery amount were measured. As a result, 95% of the theoretical hydrogen generation amount could be recovered. The reason for not reaching the recovery rate of 100% is that the leaching rate is rapidly slowed at the end of the reaction, so that the leaching rate of the metals of nickel and iron does not reach 100% and the reduction rate of iron and nickel does not reach 100%. .

The method for recovering nickel from the nickel-containing raw material of the present invention includes the step of removing iron from the nickel-containing solution in the leaching step after separating the nickel-containing solution from the nickel-containing solution with the solid residue. .

After obtaining a nickel-containing solution containing iron, blowing air while adjusting the pH of the solution to be in the range of 2.5-5.5 to remove the Fe component, Fe is converted to iron hydroxide to produce orange iron hydroxide, which is filtered And iron can be separated. In addition, a solvent extraction method may be used to separate iron and nickel ions.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example

Example  One

In order to measure the reduction rate and nickel leaching rate according to the pretreatment conditions of the nickel-containing raw material, the following experiments were performed using nickel ore of limonite and sapolite having the composition shown in Table 1.

Ni Fe Mg Si Al Limonite 1.32 47.17 1.36 1.93 2.49 Sapolite 1.96 24.37 9.94 16.1 1.5

In Table 1, the content unit of each component is weight percent, the balance is oxygen, and includes a trace amount of Mn.

The nickel ore of Table 1 was ground and calcined under the pretreatment conditions as shown in Table 2 to prepare a sample.

Ni-containing raw materials were reduced at a temperature of 700 ° C. by using twice the number of moles of hydrogen as the reducing gas with respect to the number of moles of (Fe + Ni) included in each of the samples. Water vapor and excess hydrogen produced in the reduction reaction were discharged as exhaust gas.

The reduced nickel-containing raw material was slurried by feeding to a tank containing oxygen and containing water. Hydrochloric acid was added to the obtained slurry at a molar number of 1 times the number of moles of (Fe + Ni) contained in the sample, and the sample was dissolved at a temperature of 30 ° C. to leach nickel. The leaching reaction was performed until the pH of the solution was 0.5, the time required for this time was 1 hour 45 minutes. Hydrogen gas produced in the leaching reaction was discharged as exhaust gas.

After completion of the leaching reaction, the solid residue sludge was removed using a solid-liquid separator to obtain a nickel-containing solution. Oxygen was added while adjusting the obtained nickel-containing solution to pH 3 to convert iron in the solution to iron hydroxide, and iron hydroxide was filtered to recover nickel.

The reduction rate and nickel recovery rate of the sample were investigated, and the results are shown in Table 2.

Ore class Crushing granularity
(mm) Firing temperature
(℃) Nickel leaching rate
(%) Remarks Comparative Example 1 Limonite 2 500 87 Pump clogging Inventory 1 Limonite 0.8 500 95 Inventory 2 Limonite 0.4 500 95 Comparative Example 2 Limonite 0.8 200 89 Some non-reduced Comparative Example 3 Sapolite 0.8 500 89 Some non-reduced Inventory 3 Sapolite 0.8 700 95 Comparative Example 4 Limonite 0.8 900 95

From Table 1, when the particle size of the ore exceeds 1 mm (Comparative Example 1), the acid dissolution rate is slow during the reduction reaction and the leaching reaction, so the leaching rate of nickel is lowered. You can see pump clogging.

On the other hand, in the case of Comparative Examples 2 and 3, the calcination temperature is low so that the crystallized water in the ore is not sufficiently dehydrated. When hydrogen reduction is performed in such a state, hydrogen reduction is poor and the leaching rate is low. On the other hand, in the case of Comparative Example 4, the firing was carried out at a temperature higher than the firing temperature range of the present invention, it is possible to obtain a high nickel leaching rate even under these conditions, but the subsequent increase in hydrogen reduction rate and nickel leaching rate is insignificant However, there is a problem of only increasing energy consumption.

On the other hand, in the case of Inventive Examples 1 to 3 satisfying the conditions of the crushing particle size and the firing temperature as the pretreatment conditions of the present invention it can be confirmed that the hydrogen reduction occurs well, the leaching reaction occurs well, and even within two hours even leaching at room temperature It can be seen that a high nickel leaching rate is obtained.

Example  2

In the present Example, the reduction rate when reducing by reduction temperature using nickel ore as shown in Table 3 and the ignition or combustion phenomenon according to the method at the time of extraction after reduction are observed.

Ni Fe Mg Si Al Limonite 1.32 47.17 1.36 1.93 2.49 Sapolite 1.96 24.37 9.94 16.1 1.5 Kiln Dust from Nickel Ore Dry Smelting Process 2.27 18.51 14.60 16.80 0.90

* In Table 3, the content unit of each component is weight percent, the balance is oxygen, and includes a trace amount of Mn.

Of the samples in Table 2, limonite was prepared by pretreatment as inventive example 1 of Example 1, and saprolite was prepared by pretreatment as inventive example 3 of Example 1 to prepare a sample.

For each sample of dust (hereinafter referred to as 'dust') from the prepared limonite, saffolite and nickel ore dry smelting process, the reduction temperature for each sample was performed at a temperature as shown in Table 3. Except that was reduced as in Example 1.

The reduction rate of the sample obtained by the reduction step was collected by cooling the steam generated by the reaction of the formula (1) and calculating the amount of steam generated relative to the FeNi input equivalent. The results are shown in Table 4.

As shown in Table 4, the reduced sample was fed to a tank containing oxygen and contained water, and slurried or extracted into air. Accordingly, it is observed whether or not the sample is ignited by the exothermic due to Fe oxidation and the flame propagation due to the exotherm during extraction outside the reduction furnace, and the results are shown in Table 4.

Ore class Reduction temperature (℃) Reduction rate Extraction of Reduced Samples Comparative Example 5 Limonite 500 35% - Comparative Example 6 Limonite 625 88% Air extraction. Fire Comparative Example 7 Limonite 750 97% Air extraction. Fire Comparative Example 8 Limonite 825 98% Air extraction. Fire Comparative Example 9 Limonite 960 98% Sintered Comparative Example 10 Sapolite 725 98% Air extraction. Fire Reference Example 1 Dust 825 98% Air extraction. Good Honorable 4 Limonite 625 88% Water extraction. Good Inventory 5 Limonite 750 97% Water extraction. Good Inventory 6 Limonite 825 98% Water extraction. Good Honorable 7 Dust 725 98% Water extraction. Good

As can be seen from the results of Comparative Example 5 in Table 4, the reduction of the hydrogen gas of nickel and iron occurs at a temperature of 550 ° C. or higher, and is not reduced at a temperature below that, and the reduction rate is significantly low. You can check it. On the other hand, as described in Comparative Example 9, when the reduction temperature is higher than 950 ° C., the sintering reaction of the sample occurs, which causes problems such as adhesion to equipment in the reduction furnace.

On the other hand, in the case of Comparative Examples 6 to 8 and 10 to extract the sample outside the furnace after the reduction, the phenomenon that the sample is ignited by the heat generated by the oxidation of Fe and the flame propagation due to the heat generated during the extraction process. This ignition phenomenon was confirmed to occur more severely in limonite containing a large amount of Fe in the sample.

On the other hand, as in Comparative Example 10, raising the reduction temperature prevents the ignition problem occurring during extraction in the air, but causes the sintering of the sample, causing a problem of sticking in a facility such as a rotary kiln. Furthermore, there exists a possibility that it may have a bad influence also in a subsequent leaching process. In Reference Example 1, when the kiln dust is reduced at 825-850 ° C., the iron content in the dust is low, so even if extracted into the air, no problem of ignition of the sample occurs, but it is applied to a sample having a high iron content. There is also a risk of fire.

On the other hand, Inventive Examples 4 to 7 performed a reduction reaction within the temperature range defined by the present invention, and showed a high reduction rate. Also, by extracting the reduced sample into a tank filled with oxygen-blocked water, The reduced iron content prevented the sample from igniting. The reduced sample deposited in water is limited in oxidation due to the small oxygen in the water. It may also be supplied in the form of a slurry in a subsequent leaching process. In addition, the water storage tank in the reduction furnace extraction unit as a barrier to prevent out-of-hydrogen discharge and ingress of oxygen in the furnace, can provide a so-called water sealing effect to provide a base for hydrogen recycling.

Example  3

In order to verify the hydrogen recycling due to the reaction of Equations 1 and 3, 1 mol of nickel oxide and 1 mol of iron oxide were used as a reducing gas with hydrogen gas in a tube furnace at 750 ° C, and the following equations (5) and (6) and Reduction was carried out in the same reaction, and the discharged water vapor was collected by passing through a condenser. The amount of water vapor collected was quantified.

NiO + H ₂ = Ni + H ₂ O (5)

Fe ₂ O ₃ + H ₂ = 2Fe + 2H ₂ O (6)

The steam produced after the reduction of iron oxide and nickel oxide was 17.8g and 35.9g, respectively, which is almost in agreement with the theoretical amount.

NiFe + 4HCl = NiCl ₂ + FeCl ₂ + 2H ₂ (7)

Meanwhile, reduced nickel and 1 mol of iron were dissolved in hydrochloric acid to generate hydrogen. The reaction was completed within 1 hour (pH = 0.5. No hydrogen gas was observed visually). At this time, the amount of hydrogen discharged during the reaction was collected and the amount thereof was measured. As a result, about 42.7 L was collected. It did not reach 44.8 liters corresponding to 2 mol hydrogen which is a theoretical value of Formula (7). The reason behind the theoretical value is that the leaching rate is rapidly slowed at the end of the reaction, so the metal leaching rate is not 100%, and the reduction rate of the used iron and nickel is not 100% as confirmed in Example 1.

Claims (14)

A reduction step of reducing the nickel-containing raw material at a temperature of 550-950 ° C. using a reducing gas containing at least two times the number of moles of hydrogen with respect to the number of moles of Fe + Ni of the nickel-containing raw material;
A slurrying step of slurrying the reduced nickel-containing raw material;
Leaching step of leaching nickel by dissolving the nickel-containing raw material by adding a slurry-containing raw material and acid to the reactor in an oxygen-free state;
A solid-liquid separation step of filtering and removing the residue sludge from the solution obtained by the leaching step by a solid-liquid separator; And
And removing iron from the nickel-containing solution. 2.
The method for recovering nickel from a nickel-containing raw material according to claim 1, wherein the nickel-containing raw material is obtained by drying nickel ore, pulverizing to a particle size of 1 mm or less, and firing at 250-850 ° C.
The method for recovering nickel from a nickel-containing raw material according to claim 1, wherein the nickel-containing raw material is dust obtained in a step of dry smelting nickel ore.
The method of claim 1, wherein the reducing gas containing hydrogen is a gas containing only hydrogen or a mixed gas of nitrogen and hydrogen.
The method of claim 1, wherein the slurrying step is performed by immersing the reduced nickel-containing raw material in a tank containing oxygen-blocked water.
The method for recovering nickel from a nickel-containing raw material according to claim 1, wherein the acid is sulfuric acid, and the sulfuric acid is added at a molar number of one or more times the number of moles of (Fe + Ni) of the nickel-containing raw material.
The method for recovering nickel from a nickel-containing raw material according to claim 1, wherein the acid is hydrochloric acid, and the hydrochloric acid is added at a molar number not less than twice the number of (Fe + Ni) moles of the nickel-containing raw material.
The method of claim 1, wherein the leaching step is stopped when the pH of the solution is in the range of 0.1-1.0.
The method of claim 1, wherein the leaching step is to recover the nickel from the nickel-containing raw material, characterized in that carried out for 0.5 to 2 hours at a reaction temperature of 25-80 ℃.
The method of claim 1, wherein the iron removal step is performed by adjusting the pH of the nickel-containing solution in the range of 2.5-5.5 by injecting an oxygen-containing gas to produce iron hydroxide, filtering the produced iron hydroxide, or by solvent extraction. A method for recovering nickel from a nickel-containing raw material, characterized in that it is carried out.
The method for recovering nickel from a nickel-containing raw material according to any one of claims 1 to 10, wherein hydrogen is collected from the exhaust gas discharged in the reduction step and re-supplied to the reduction step.
12. The nickel-containing raw material according to claim 11, wherein the hydrogen collection from the exhaust gas is performed by cooling the exhaust gas containing steam and hydrogen to remove dust containing water generated by condensation of the steam. How to recover.
The method for recovering nickel from the nickel-containing raw material according to any one of claims 1 to 10, wherein the hydrogen generated in the leaching step is collected and re-supplied to the reduction step.
11. The method according to any one of claims 1 to 10, wherein the dust containing hydrochloric acid mist is removed by using a scrubber from a flue gas containing hydrochloric acid mist and hydrogen discharged in the leaching step, and hydrogen is collected to reduce the dust. A method for recovering nickel from a nickel-containing raw material, characterized in that it is resupplied to.