KR20140043001A - Ferro-nickel recovery method by recycling the leached and washed solution - Google Patents

Abstract

The present invention relates to a method for recovering nickel from nickel ore containing nickel and iron as the form of ferronickel by recycling washing liquid of residual sludge generated in a process for manufacturing solution containing nickel ion by acid leaching the nickel ore. The method for recovering nickel comprises: a step for obtaining a reducing base material for leaching by reducing base material powder containing nickel and iron to reducing gas containing hydrogen, and for manufacturing reducing base material slurry for leaching by making the reducing base material for leaching the slurry by using water in the inert atmosphere; a step for separating the solution containing nickel and iron ion from the residual sludge after solution-leaching nickel and iron to ion by inserting acid such as sulfuric acid or hydrochloric acid into the reducing base material slurry for leaching; and a step for precipitating ferronickel by reducing iron of the reducing base material for precipitating to nickel inside the solution containing nickel and iron ion by inserting the reducing base material slurry for precipitating into the solution containing nickel and iron ion. The reducing base material for precipitating is obtained by reducing a base material containing nickel and iron to gas containing hydrogen in the solution containing nickel and iron ion. The reducing base material slurry for precipitating contains the reducing base material for precipitating of a content of 10-40 wt% about the total weight percentage of the reducing base material for precipitating and the reducing base material for leaching. Provided is the ferronickel recovery method to obtain washing liquid containing nickel ion among residual sludge by washing the residual sludge with water, and to use the washing liquid as water for making the reducing base material for leaching the slurry.

Description

Technical Field [0001] The present invention relates to a ferro-nickel recovery method using a residual sludge washing liquid in a nickel smelting process,

The present invention relates to a method for recovering nickel from a nickel ore containing nickel and iron by recycling the recovered wastewater from the residue sludge generated during the acid leaching of nickel ore to nickel ion containing solution .

Nickel-containing ores are limonite, saprolite, and ore. These ores have passive properties, so they are resistant to acids and thus have a slow acid dissolution reaction. As a method for effectively leaching nickel, there have been proposed methods for recovering nickel by dissolving the acid in an autoclave under high temperature and high pressure, and this is called 'HPAL (High Pressure Acid Leaching) method'.

When the nickel leaching reaction is carried out at room temperature, the nickel recovery rate does not exceed 85% even after leaching for several months or longer. However, when the HPAL method is used, leaching of nickel at 90% or more is possible within 2 hours, .

Examples of techniques for recovering nickel by the HPAL method include Korean Patent Publication No. 2007-7020915 and Japanese Patent Laid-Open No. 2010-031341. However, it is known that the HPAL method should be performed under high temperature and high pressure of the autoclave, and it is known that only the titanium material can be mainly used due to its strong acidity, and accordingly, the equipment cost is very high and the maintenance cost is high. In addition, the use of caustic soda, which is an expensive precipitant, or the use of an environmentally harmful precipitant (H ₂ S) is required to concentrate nickel, and thus there is a problem in that the equipment cost for treating such a problem is increased.

On the other hand, the present inventors have proposed a method for recovering nickel by acid leaching after hydrogen reduction of a nickel-containing raw material in Korean Patent Publication No. 2009-0031321. In the technique of the patent document, V and Mo are recovered from a petrochemical desulfurization spent catalyst and the remaining residue is treated with an acid to remove alkali elements in the residue; Drying the residue from which the alkali element has been removed, and then performing a heat treatment in a reducing atmosphere at a temperature range of 600-1300 캜 to reduce Ni and Fe existing in an oxide form in the residue to a metal; Leaching the reduced product obtained in the above step with an acid to selectively dissolve iron and nickel; Filtering the solution to obtain leached nickel and iron ion-containing solution; Neutralizing the solution containing Ni and Fe ions with alkali to make Fe and Ni hydroxide; And a step of filtering and drying the product obtained in the above step to obtain Fe and Ni-containing raw materials, and a method for producing iron nickel-containing raw materials from petrochemical desulfurization spent catalyst recycled residues.

However, in the past, waste generated during the nickel smelting process has been discharged and processed. As a result, separate costs are required for waste treatment.

The present invention provides a method for producing ferronickel by recovering nickel from a nickel ore, recycling the wash water of the residue sludge generated in the course of producing a nickel solution by acid leaching of the nickel ore.

The present invention relates to a method for recovering ferronickel, wherein the nickel iron-containing raw material powder is reduced with a reducing gas containing hydrogen to obtain a leaching raw material, and the leaching raw material is leached by slurrying with water in an inert atmosphere. Preparing a reducing raw material slurry for sulfuric acid, adding sulfuric acid or hydrochloric acid to the leaching raw material slurry, dissolving and leaching nickel and iron with ions, and separating a nickel iron ion-containing solution from the residue sludge; Precipitation including the precipitation reduction raw material obtained by reducing nickel and iron-containing raw materials with a gas containing hydrogen in the iron ion-containing solution in an amount of 10 to 40% by weight based on the total weight of the leaching reduction raw material and the precipitation reducing raw material. The reducing raw material slurry was added to the nickel iron ion-containing solution, and the iron of the reducing raw material for precipitation was nickel iron. Containing solution containing nickel ions in the residual sludge is obtained by washing the residue sludge with water to obtain a washing solution containing nickel ions, and the washing solution is slurried And recovering the ferronickel.

In the present invention, the washing liquid can be obtained by washing with 1 to 4 L of water per 1 kg of the residual sludge and removing the solid content.

It is preferable that the pH of the washing liquid is adjusted to 1.5 to 4.0.

In addition, it is preferable that the wash water is blown with nitrogen.

Further, the slurry for reducing raw materials for leaching can be prepared by mixing the wash liquid at 1 to 2 times the weight of each reducing raw material.

On the other hand, the precipitation reducing slurry can also be obtained using the wash water.

The precipitation reducing raw material slurry may also be prepared by mixing the wash water solution with 1 to 2 times the weight of each reducing raw material.

According to the method of the present invention, the leachate washing liquid generated in the process of recovering nickel from nickel ore can be recycled, and waste generation can be reduced.

Further, it is not necessary to use an environmentally hazardous precipitant such as H ₂ S or expensive caustic soda as a precipitant conventionally used in the nickel smelting process, thereby reducing burden on the environment and reducing the processing cost.

Hereinafter, the present invention will be described in detail.

The present invention relates to a nickel smelting method for recovering a nickel concentrate from a raw material containing nickel and iron, and a method for recovering ferronickel by recycling leachate washing liquid generated during the process.

The nickel-iron-containing raw material to which the present invention can be applied is not particularly limited, and any nickel or iron-containing raw material may be used as long as it contains nickel and iron, and preferably nickel ores such as limonite, . Nickel ore has a content of Ni 1-2.5% and Fe 15-55%, though the amount varies depending on the type of ore. In the case of limonite ores, the nickel concentration is as low as 1-1.8% and the iron concentration is 30-55 %. The present invention can also be effectively applied to recovering nickel from such a relatively low nickel content limbite.

In recovering nickel from the nickel-iron-containing raw material, the nickel-iron-containing raw material can be subjected to a pretreatment process if necessary in order to effectively reduce the nickel-iron-containing raw material in the reduction process described below. Such pretreatment processes include drying, grinding and calcining steps.

The nickel-iron-containing raw material, which is the raw material used for nickel recovery, is preferably an atomized powder for efficient reduction and a smooth leaching process. Therefore, it is preferable that the nickel-containing ore is previously pulverized and applied to the nickel recovery process.

In this case, the nickel-iron-containing raw material, which is usually used as raw material, generally contains about 30 to 40% of the number of the attached water and about 10% of the crystalline water. In order to improve the pulverization efficiency, . The drying of the nickel ore can be carried out under the condition that the water of adhesion in the nickel ore can evaporate, for example, by heating to a temperature in the range of 100 to 200 ° C.

And the step of pulverizing the nickel-iron-containing raw material after drying. At this time, it is preferable to crush the particle size to 1 mm or less in order to improve the reduction and leaching efficiency. On the other hand, the lower limit of the particle size is not particularly limited, but it is preferable to grind to a size of 10 탆 or more for convenience of the grinding process.

On the other hand, the crystal water contained in the nickel-iron-containing raw material that has not been removed in the drying process is released as water in the reduction process during the reduction reaction of the nickel-iron-containing raw material. , It is preferable to calcine the nickel-iron-containing raw material to remove such crystal number.

Among the nickel-iron-containing raw materials, the limonite ore has a property of emitting crystal water at about 250-350 ° C and the saprophorite ore at around 650-750 ° C. Therefore, the nickel iron-containing raw material powder can be subjected to a calcination treatment at 250-850 DEG C to remove crystal water.

On the other hand, nickel can be recovered from a rotary kiln dust generated in a dry smelting process using the saprophylite ore by applying the present invention. However, since dust is contained in a range suitable for applying the present invention to the particle size and is exposed to a high-temperature state during the dry smelting process, there is no need for a crushing and firing treatment process as in the case of the nickel-iron- Followed by grinding or firing.

In addition, when an oil refinery uses a catalyst containing nickel as a catalyst, a waste catalyst residue containing nickel and iron is generated, from which nickel can be concentrated and recovered. Such a waste catalyst residue is generally contained in a range suitable for applying the present invention, so that a pulverizing step is not necessary, but if it is aggregated, it can be pulverized by an appropriate means, and if necessary, . ≪ / RTI >

The present invention includes a step of reducing nickel and iron of the pretreated nickel-containing iron-containing raw material as described above. This reduction step can be performed at a temperature range of 550-950 DEG C using a reducing gas containing hydrogen as a reducing agent. When the reduction temperature is less than 550 ° C., the reduction does not occur sufficiently, so that the recovery rate upon leaching into the acid solution in the subsequent step is low, and the precipitation yield is also lowered. On the other hand, the higher the reducing temperature, the higher the leachate yield and precipitation yield. However, in the case of reduction at a temperature exceeding 950 占 폚, there is no problem in reducing the nickel-iron-containing raw material, however, no further reduction in the reduction efficiency can be obtained and, rather, intergranular sintering may occur, The specific surface area is reduced to 1 m < 2 > / g or less, which may result in a decrease in precipitation yield.

As the reducing gas, a gas containing hydrogen may be used. When a hydrogen-containing gas is used as the reducing gas, a reduction process can be performed at a lower temperature than the carbon reduction, and a nickel metal having a specific surface area of 1-100 m 2 / g can be produced, It can be easily dissolved by the acid, so that the subsequent acid leaching process can be carried out at high speed.

As such a reducing gas, not only hydrogen can be used alone, but also inert gases such as helium, argon, carbon dioxide, and nitrogen can be used together. Further, another example that can be used as the hydrogen-containing reducing gas is a gas generated from a coke oven gas (COG) containing 50% or more of hydrogen generated in the iron ore smelting process or a methane hydrogen reforming reaction, And hydrogen-containing LNG reforming gas containing 65% or more of hydrogen.

For example, in the case of using limonite ore (nickel: iron = 1: 29) as the nickel-iron-containing raw material as a reducing gas using hydrogen, a reducing raw material is obtained by a theoretical reduction reaction as shown in the following formula (1) Loses.

Hydrogen used as a reducing gas in this reduction reaction reacts with oxygen of nickel and iron present in the oxidized state in the nickel iron-containing starting material to produce water, thereby reducing the nickel and iron. Therefore, the amount of hydrogen contained in the reducing gas may be included in an amount equal to or greater than the theoretical equivalence ratio, and hydrogen may be added in excess of the theoretical equivalence ratio for efficient reduction reaction. However, such a hydrogen is expensive, and the higher the equivalent ratio of hydrogen to the hydrogen is, the higher the cost of the process is, and it is not preferable to use the hydrogen excessively, and hydrogen can be supplied in an appropriate amount. For example, the amount of hydrogen introduced may be included in the molar amount of, for example, 1 to 5 times, 2 to 5 times, or 2 to 4 times the theoretical equivalent ratio.

The nickel iron-containing raw material reduced by this reaction can be obtained. The reduced nickel iron-containing raw material is hereinafter also referred to as a reducing raw material.

After the exhaust gas obtained in the reduction step is discharged and separated, the reducing raw material is slurried by using water. Reduction of nickel ore results in a very high iron content, so when the iron ore is extracted into the air after reduction, the activity of the reducing powder becomes very high (specific surface area 1-100 m ² / g), and oxidation of the reduced iron component occurs at room temperature . Therefore, the oxidation reaction is accelerated due to the heat generated during the oxidation, so that the risk of fire is obtained. Therefore, it is preferable that the reduced nickel iron-containing raw material is immersed in water and slurried to prevent oxidation of the iron component. It is preferable that the slurrying proceeds in an oxygen-free state in which the inflow of external air is blocked in order to prevent the reducing raw material from being reoxidized by oxygen. For example, the reducing raw material may be discharged into a tank containing oxygen-blocked water to be slurried.

Water may be administered to bring the slurry concentration to 1-2 times the weight of the reducing raw material. If the water content is out of the above range and the water is too small, the concentration of the slurry may be high, which may cause transfer problems. If the water is excessively administered, the concentration of the solution after dilution becomes undesirably low.

At this time, general water may be used as the water to be used, but a washing liquid obtained in a washing process for washing the residue sludge to be described below may be used. Specific details will be described in detail below.

And an acid leaching step in which an acid is added to the slurry of the reducing raw material to dissolve the ferronickel of nickel iron contained in the reducing raw material in the slurry and leach out to ionize it with iron and nickel ions. The acid leaching step may dissolve the reducing raw material by adding an acid to the slurried reducing raw material in an anaerobic reactor and agitating it.

And leaching the reducing raw material with an acid to dissolve the nickel and iron components in an acid. At this time, the nickel iron ion-containing solution can be obtained by removing the residue by acid dissolution by filtration.

The acid used in the acid leaching step is not particularly limited, but hydrochloric acid or sulfuric acid may be used. Generally, when the reducing raw material reduced by the reduction reaction of the above formula (1) is leached out with an acid, the ferronickel in the reducing raw material is dissolved by the acid as shown in the following formulas (2) and (3) ≪ / RTI >

When hydrochloric acid is used as an acid in order to leach such a reducing raw material into an acid, hydrochloric acid should be added at a molar number twice or more the number of moles of (Fe + Ni), as can be seen from the above formula (2). However, when hydrochloric acid is added in a quantity exceeding 4 times the number of moles of (Fe + Ni), further improvement in leaching efficiency can not be obtained, and it is preferable that the molar amount is 2 to 4 times the number of moles of (Fe + Ni) Do. On the other hand, in the case of using sulfuric acid as an acid, it is preferable to be charged at a molar ratio of at least 1 and at most 2 times the number of moles of (Fe + Ni) of the nickel iron containing raw material, as can be seen from the above formula (3).

Such an acid leaching reaction is an exothermic reaction accompanied by a temperature rise in the reactor. Therefore, the acid leaching reaction can be performed even at room temperature, but it can be performed by heating the slurry to a temperature of up to 80 ° C to improve the leaching rate.

When the metal is present in the aqueous solution during the acid dissolution reaction, the ORP is negative, and when the metal is completely dissolved in the acid, the ORP is changed to zero after the ORP is zero. Therefore, when the ORP is 0 or more, the acid dissociation reaction can be stopped, and the end point of the acid dissociation reaction can be confirmed by measuring the ORP.

On the other hand, Al ₂ O ₃ , SiO ₂ , and Cr ₂ O ₃ contained in the nickel-iron-containing raw material hardly dissolve by the acid, and are obtained as solid phase residues. Therefore, the iron and nickel ion-containing solution and the solid residue obtained by the leaching step are easily separated by filtration, and are separated by a solid-liquid separator such as a filter press or a decanter to obtain iron and nickel ion-containing solutions , And separates the residue sludge which is a solid residue.

Next, the step of precipitating iron and nickel ions dissolved in the reaction of the formula (2) or (3) from the obtained iron and nickel ion-containing solution into a metal is included. The precipitation of the iron and nickel ions can be carried out by introducing a reducing raw material according to the reaction of the formula (1). In order to distinguish the reducing raw materials from the reducing raw materials used for the leaching reaction for the precipitation reaction used in the precipitation reaction, they are referred to as precipitation reducing raw materials and leaching reducing raw materials, respectively.

When the precipitation-reducing raw material is charged into the iron and nickel ion-containing solution, nickel of iron and nickel ions dissolved by the reaction represented by the following formula (4) or (5) And is substituted with metal.

The principle of the substitution reaction represented by the above formulas (4) and (5) is due to the natural potential difference between iron and nickel, and is caused by a cell reaction as shown in the following reaction formula.

Anode reaction:

Cathode reaction:

Overall reaction:

That is, a battery is formed by the natural potential difference between Ni and Fe in the iron and nickel ion-containing solution, and the dissolution reaction by the oxidation of Fe proceeds in the anode site, and the iron and nickel ion The reaction in which nickel ions in the solution are reduced and precipitated proceeds.

However, when the reducing raw material reduced by the reduction reaction of the formula (1) is fed into the iron and nickel ion-containing solution, nickel can be effectively precipitated and recovered even when it is added in a small amount.

The amount of the precipitation reducing material to be added to the iron and nickel ion-containing solution for the reduction of nickel may be adjusted according to the amount of the reducing reducing material for leaching.

The amount of the precipitation-reducing raw material is not necessarily limited to this, but may be 10 to 40% by weight based on the total amount of the raw materials used in the ferro-nickel recovery step, that is, Lt; / RTI >

(4) or (5) is carried out by adding a precipitation reducing raw material to the iron and nickel ion-containing solution obtained by the reaction of the above formula (2) or (3) to precipitate ferronickel .

From the solution obtained by the precipitation reaction as described above, the solid content containing ferronickel is separated by filtration to remove the iron ion-containing solution, thereby obtaining a nickel concentrate having increased nickel concentration.

When the concentration of nickel in the nickel concentrate thus obtained reaches 4.5-20%, raw materials can be obtained in the form of ferro-nickel.

Therefore, the ferronickel type nickel concentrate obtained by the reaction of the equations (4) and (5) and the Fe ion dissolved in FeCl ₂ can be separated through the solid-liquid separator, so that the solution containing Fe ions can be selectively removed , And the solid ferronickel can be concentrated.

Meanwhile, the leaching reaction may include a step of obtaining iron and nickel ion-containing solution, washing the separated residue sludge with water, and washing and recovering nickel ions contained in the residue sludge. Hereinafter, this step is referred to as a flushing step for convenience. The residue sludge may contain nickel ions. The residue sludge may be washed with water to recover nickel ions contained in the residue sludge. Whereby the wash water of the residue sludge containing nickel ions can be recycled in the present nickel smelting process.

In the nickel smelting process, water is used in slurrying the reducing raw material, and water may be used to wash the residual sludge. As described above, water is used to slurry the reducing raw material or to wash residual sludge. When the amount of water used increases, the concentration of Cl is lowered in the subsequent Cl recovery process in which Cl is recovered by evaporation concentration, There is a problem that gives. Therefore, as in the present invention, the amount of water used can be reduced by reusing the wash water of the residue sludge during the process, thereby minimizing the concentration decrease of Cl, which is preferable.

The amount of water used in the washing step is not particularly limited, but it is necessary that the amount of the sludge discharged is sufficient to wash the sludge sufficiently. When the amount of water is small, sufficient water washing can not be performed, and nickel ions contained in the residual sludge can not be sufficiently recovered. When a large amount of water is used, excessive use of nickel ions is excessively used, Further, it is possible to dilute the above-mentioned effect due to the recycling of the wash liquid. For example, water may be used in an amount of 1 to 4 L per 1 kg of residue sludge. Preferably 2 to 3L.

Typically, iron ions are contained in an amount of 15-30 g / L and nickel ions are contained in an amount of 0.5-1 g / L, and the pH of the washing liquid is 0.1 -1.5. Such a washing liquid can be used for slurrying the reducing raw material.

However, it is preferable that the pH of the washing liquid is adjusted to 1.5 to 4.0. Since the wash liquor obtained by the washing process has a low pH as described above, the slurry tank can be corroded when the wash liquor is directly used in the slurry of the reducing raw material. In other words, it is preferable to use a metal-made tank because the reducing material slurry tank can not use materials such as FRP because of the possibility of high heat of the reducing raw material. Since such metal tanks have very low resistance to acids, It is preferable to adjust the pH to the above range. If the pH is lower than 1.5, corrosion of the equipment will proceed rapidly even if the stainless steel material is used. If the pH is higher than 4.0, the amount of acid used in the subsequent leaching process may increase.

On the other hand, the obtained washing liquid contains iron ions, and if it is left in the air for a long time, it is likely to re-oxidize to Fe ^{+ 3} . Therefore, it is preferable that the obtained washing liquid is used for slurrying the ore by blowing nitrogen into the solution to prevent the oxidation of the iron ions in the solution.

In the case of using the washing solution (the washing solution obtained after the leaching reaction with hydrochloric acid) as the solution for slurrying the reducing raw material, the nickel ion in the washing solution is replaced with the reducing raw material by the following formula (6) Lt; / RTI >

That is, the nickel ion present in the washing liquid is displaced by the metallic iron of the reducing raw material, so that the nickel concentration of the reducing raw material becomes high. As a result, when the slurry of the reducing raw material having increased nickel concentration is re-leached with hydrochloric acid or sulfuric acid, a solution containing iron and nickel ions having a high nickel concentration can be obtained.

On the other hand, when a reducing material is added to the iron and nickel ion-containing solution obtained after leaching reaction with hydrochloric acid, a ferronickel precipitate having a higher nickel concentration can be obtained by the reaction of the following formula (7).

Particularly, since the concentration of nickel in the washing liquid is small, the substitutional precipitation reaction as described above does not occur normally. However, as described above, when the wash liquid is recycled as a slurry solution of a reducing raw material, the nickel concentration in the leaching solution can be naturally increased. Therefore, the recovery rate of nickel precipitation can be increased. Namely, when a part of the reduced ore is administered for precipitation, nickel can be effectively precipitated and recovered even when a small amount of a raw material for precipitation reduction is added.

Particularly, in the precipitation reaction, nickel in the reducing raw material for precipitation can be recovered 100%, and iron in the reducing light can effectively deposit nickel of the leaching solution with high efficiency, so that the nickel recovery rate is very high and the nickel concentration of the precipitate is high.

Nickel ions can be recovered from the residue sludge remaining after the iron and nickel ion-containing solution is obtained from the leaching reaction by the above-described method, and the nickel ion can be recovered by washing the remaining sludge. By using the wash liquid thus obtained, , An increase in the recovery rate of ferro nickel deposition, and an increase in the nickel concentration of the precipitate.

Example

Hereinafter, the present invention will be described in detail with reference to examples. The following examples are illustrative of the present invention and are not intended to limit the present invention.

Manufacturing example

Limonite  Pre-treatment of ore

The limonite ores having a composition as shown in Table 1 were dried in a rotary kiln at 150 ° C for 1 hour and then pulverized using a super mill to prepare powders. Powders were classified by particle size A powder having a particle size of 0.8 mm was obtained.

The obtained powder was fired in a firing furnace maintained at 300 캜 for 1 hour to remove crystal water from the ore powder.

Production of reducing raw materials

The calcined nickel light was discharged from a firing furnace and charged into a rotary kiln reduction furnace in which oxygen had been shut off. Thereafter, hydrogen at a molar ratio of (Ni + Fe) 4 times the molar amount contained in the prepared ore powder was used, Reduced light was produced by reducing ore.

The components of the reduced light obtained by such reduction are analyzed and shown in Table 1. [

Ni Fe Mg Si Al Limonite 1.4 42.3 1.1 1.1 2.5 Reduction light 2.0 60.5 1.65 1.6 3.6

In Table 1, the content of each component represents weight%, and the balance is oxygen and trace amounts of Mg and Mn.

The thus-prepared reduced light was cooled in an oxygen-free tank filled with nitrogen gas, and 200 ml of water was added to 200 g of the reduced light to prepare a slurry.

Leaching reaction

A 20% strength hydrochloric acid solution was added to the above-prepared reduced optical slurry to prepare a 1 L solution. The solution was stirred at room temperature to dissolve the reducing light to effect leaching of iron and nickel ions.

The ORP was measured while performing an acid leaching reaction of the reduction light on the slurry, and it was confirmed that the ORP value changed from - to +, and the reaction was stopped.

The solid residue was filtered from the leaching solution obtained by the leaching reaction to obtain 750 cc of iron and nickel ion-containing solution (simply referred to as leach solution), and the solid residue was separately separated. The nickel concentration in the obtained leachate was analyzed and found to be 4.9 g / L.

Residue Sludge  Wash step

250 ml of water was added to the obtained residue sludge, and the resultant was washed for 30 minutes. The solid component was removed by filtration to obtain a washing solution.

The nickel concentration in the obtained washing liquid was analyzed and found to be 0.8 g / L. On the other hand, the iron ion concentration in the washing solution was 25 g / L and the pH of the solution was 0.5.

Comparative Example  One

The washing liquid was mixed with the leaching solution. The ICP analysis of the leach solution thus obtained confirmed that the solution had a nickel content of 3.88 g / L. The precipitation reaction was carried out using this solution. The precipitation reaction was carried out as follows.

Precipitation reaction

In order to precipitate ferronickel from the obtained leaching solution, 80 g of water, which is the same as the reducing light used for the leaching reaction, was added to 80 g of water as a slurry for precipitation, and slurried to prepare a slurry for precipitation reduction. The above-mentioned reduced optical slurry for precipitation was charged into the obtained leaching solution to carry out a displacement precipitation reaction of ferronickel for 2 hours.

From the solution obtained by the precipitation reaction as described above, the solid content including ferronickel was separated by filtration with a solid-liquid separator and recovered.

The Ni in the precipitated ferronickel was analyzed by ICP to calculate the recovery rate of nickel (amount of Ni in the precipitate) / (Ni concentration in the ore). The results are shown in Table 2.

Example  1 to 3, Comparative Example  2 and 3

The pretreatment of the limonite ores, the preparation of the reducing raw material and the leaching reaction were carried out by the same conditions and methods as those of the above-mentioned production example. In the production process of the reducing raw material, the water used to prepare the slurry of the reducing raw material was used as the wash water obtained in the above Production Example.

On the other hand, when the wash liquid obtained in the above-mentioned production example was stored, the gas input conditions were changed as shown in Table 2 below. Further, CaO was used as an alkaline agent to adjust the pH of the washing liquid. The pH was adjusted by adjusting the amount of CaO to be varied as shown in Table 2.

The precipitation reaction was carried out in the same manner as in Comparative Example 1, using the wash liquor according to each of Examples 1 to 3 and Comparative Examples 2 and 3, and the solid content including ferronickel was recovered in the same manner.

The Ni in the precipitated ferronickel was analyzed by ICP to calculate the recovery rate of nickel (amount of Ni in the precipitate) / (Ni concentration in the ore). The results are shown in Table 2.

Washable recycled solution conditions Leachate concentration
(g / L) Nickel recovery Remarks atmosphere pH Comparative Example 1 Do not recycle 0.5 3.8 94% Inventory 1 nitrogen 1.5 4.9 98% Inventory 2 nitrogen 2.5 4.9 98% Inventory 3 nitrogen 3.5 4.9 98% Comparative Example 2 nitrogen 4.5 4.8 96% Increased use of hydrochloric acid Comparative Example 3 air 2.5 4.7 95% Co-ordination loss

According to Table 2, as can be seen from Examples 1 to 3, it can be confirmed that when the wash liquid is recycled and used, the concentration of the leachate increases, thereby increasing the recovery rate of nickel precipitation.

This is because the nickel concentration in the solution becomes higher, and the nickel substitution precipitation reaction is more likely to occur, thereby increasing the recovery rate of nickel precipitation.

On the other hand, if the pH of the washing liquid is not adjusted, the corrosion of the recycling tank may occur, and the pH of the solution should be 1.5 or more. On the other hand, as can be seen from Comparative Example 2, when the pH of the wash liquor is too high, hydrochloric acid is used in the leaching reaction instead of the leaching reaction in the subsequent leaching step to lower the leaching recovery rate.

In addition, it was confirmed from the comparative example 3 that if the non-oxidizing atmosphere was not maintained in the process of recycling the wash liquor, the Fe precipitates as FeOOH in the tank, and the nickel precipitate also occurs.

Claims (7)

A step of reducing the nickel-iron-containing feedstock powder with a reducing gas containing hydrogen to obtain a reducing raw material for leaching, and slurrying the leaching reducing raw material in an inert atmosphere using water to prepare a slurry for reducing leaching;
Adding an acid of sulfuric acid or hydrochloric acid to the leaching raw material slurry for dissolving and leaching nickel and iron with ions, and separating the nickel iron ion-containing solution from the residue sludge;
The precipitation reduction raw material obtained by reducing the nickel and iron containing raw material with the hydrogen-containing gas into the nickel iron ion-containing solution is contained in an amount of 10 to 40% by weight based on the total weight of the raw materials for leaching and the precipitation reducing raw material Wherein the precipitating reducing raw material slurry is introduced into the nickel iron ion containing solution so that the iron of the precipitation reducing raw material is replaced with nickel in the nickel iron ion containing solution to precipitate ferronickel,
Wherein the residue sludge is washed with water to obtain a wash water solution containing nickel ions in the residue sludge and the wash water is used as water for producing the slurry for leaching reduction raw material.
The ferronickel recovery method according to claim 1, wherein the wash liquid is obtained by washing with 1 to 4 L of water per 1 kg of the residue sludge and then removing solid content.
The ferronickel recovery method according to claim 1, wherein the washing liquid is adjusted to have a pH of 1.5 to 4.0.
The method of claim 1, wherein the wash liquor is nitrogen.
The ferronickel recovery method according to claim 1, wherein the reducing raw slurry for leaching is prepared by mixing the washing liquid at 1 to 2 times the weight of each reducing raw material.
The ferronickel recovery method according to claim 1, wherein the precipitation reducing raw material slurry is obtained by using the wash water.
The ferronickel recovery method according to claim 6, wherein the slurry for reducing raw material for leaching and the slurry for reducing raw material for precipitation are prepared by mixing the wash liquid at 1 to 2 times the weight of each reducing raw material.