KR20130076555A - Method for recovering ferronickel from nickel ore - Google Patents

Abstract

PURPOSE: A ferronickel collecting method from a nickel (Ni) ore is provided to minimize the use of an expensive high purity hydrogen and to reduce energy consumption by using a process for preheating ore and a pre-reducing process. CONSTITUTION: A ferronickel collecting method from a nickel ore comprises the following steps. A nickel (Ni) reducing ore for leaching with 50-92% of the iron (Fe) reducing ratio is converted into slurry by mixing the nickel reducing ore with water. A solution which contains Ni ions is obtained by making Ni and Fe to be dissolved from a Ni-reducing ore for leaching after injecting acid into the slurry. The Ni-reducing ore for leaching which has 70-96% of the Fe reducing ratio is injected into the solution which includes the Ni ions, and the injected Ni reducing ore for leaching is replaced with the Ni ions in the solution which contains the Ni ions to extract ferronickel. The reducing ore for leaching is reduced by passing through the pre-reducing step and the main reducing step.

Description

Method for Recovering Ferronickel from Nickel Ore}

The present invention relates to a method for efficiently recovering ferronickel from a nickel ore by a wet process.

Ore containing nickel and iron includes ores such as limonite and saprolite, and these ores have passivation properties, so they are resistant to acids and are slow to dissolve in acids. As a method for effectively leaching nickel, there have been proposed methods for recovering nickel by dissolving in an acid in an autoclave under high temperature and high pressure, which is called 'HPAL (High Pressure Acid Leaching) method'.

When the nickel leaching reaction is performed at room temperature, the nickel recovery rate does not exceed 85% even after leaching for several months or more.However, the HPAL method enables 90% or more of nickel leaching within 2 hours. It is a representative method of smelting.

Examples of techniques for recovering nickel by the HPAL method include Korean Patent Laid-Open Publication No. 2007-7020915 and Japanese Laid-Open Patent Publication No. 2010-031341. However, HPAL method should be carried out under the high temperature and high pressure of the autoclave, and it is known that it can be mainly used only for the titanium material due to its strong acidity, and thus has the disadvantage of very high equipment cost and high maintenance cost. In addition, since a caustic soda, which is an expensive precipitant, or an environmentally hazardous precipitant such as H ₂ S must be used for nickel concentration, there is a problem in that a facility cost for treating this is increased.

On the other hand, the present inventors have proposed a method of recovering nickel by acid leaching after reducing the nickel-containing raw material in Korean Patent Publication No. 2009-0031321. The technique of the patent document is to recover V, Mo from the petrochemical desulfurization waste catalyst and to remove the alkali element in the residue by treating the remaining residue with an acid, drying the residue from which the alkali element is removed 600- in a reducing atmosphere Heat treating at a temperature in the range of 1300 ° C. to reduce Ni and Fe present in the form of an oxide in the residue with a metal, and leaching the reduced 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 Ni and Fe ion-containing solution into alkali to form Fe, Ni hydroxide, and filtering and drying the product obtained in the step to produce Fe and Ni Disclosed is a method for producing iron nickel-containing raw material from a petrochemical desulfurization waste catalyst recycling residue comprising the step of obtaining the containing raw material.

However, when leaching limonite nickel ore using the above method, high-speed leaching is possible, but limonite ore has a high iron content and a low nickel content, and when leaching nickel by acid dissolution, Fe is relatively high. While leached, nickel is leached in small amounts, which makes it difficult to separate iron and nickel from the leachate.

According to one embodiment of the present invention, to minimize the use of expensive high-purity hydrogen through the preheating and preliminary reduction process of ore in order to overcome the disadvantages of energy saving and expensive high-purity hydrogen, and to reduce the energy consumption To provide.

Furthermore, according to one embodiment of the present invention, to provide a method for producing a leaching ore and precipitation reducing ore to optimize the ferronickel recovery in nickel smelting.

The present invention relates to a method for recovering ferronickel from nickel ore. According to a first embodiment of the present invention, a slurry for mixing and slurrying a leaching nickel reducing ore having a reduction rate of iron of 50 to 92% in water is slurryed. step; Leaching step of adding an acid to the slurry to dissolve nickel and iron from the leaching nickel reducing ore to obtain a nickel ion-containing solution; And depositing nickel reduction ore having a reduction rate of 70-96% of iron in the nickel ion-containing solution, and replacing nickel ions in the nickel ion-containing solution with metal iron of the introduced nickel reduction ore to precipitate as ferronickel. It provides a method for recovering ferronickel from nickel ore comprising the step.

According to a second embodiment of the present invention, the leaching nickel reduction ore is a preliminary reduction step of preliminarily reducing the nickel ore with hydrogen-containing gas at 450-600 ℃; And it may be reduced by a method comprising a main reduction step of obtaining a reduced ore by reducing the preliminary reduced ore obtained in the preliminary reduction step with a hydrogen-containing gas at 600-950 ℃.

According to the third embodiment of the present invention, the precipitation nickel reduction ore is a preliminary reduction step of preliminarily reducing nickel ore with hydrogen-containing gas at 500-700 ° C .; And a main reduction step of main reduction of the preliminary reduction ore obtained in the preliminary reduction step into a hydrogen-containing gas at 700-1050 ° C.

According to a fourth embodiment of the present invention, the hydrogen-containing gas in each of the preliminary reduction steps may be a COG or LNG reformed gas or a mixed gas of nitrogen and hydrogen.

According to one embodiment of the present invention, by including a pre-reduction step in reducing the nickel ore it is possible to reduce the energy consumption in the reduction process of the ore.

Furthermore, according to one embodiment of the present invention, a lower hydrogen-containing gas may be used as a reducing gas in a preliminary reduction step, thereby reducing the amount of expensive hydrogen used.

In addition, the recovery of ferronickel is prepared by separately preparing the reduced ore for the leaching ore used for the acid leaching step in the wet smelting process of nickel and the precipitation ore for the precipitation of the nickel for substitution precipitation according to one embodiment of the present invention. Can be improved.

The present invention relates to a method for recovering nickel in a ferronickel form by a wet method from nickel ore, and the present invention will be described in detail below.

When nickel concentrate is acid-dissolved from a raw material containing nickel and iron, and nickel is recovered in the form of ferronickel by substitution precipitation of nickel ions, the nickel concentration is low and the iron concentration is high. While leaching a lot, nickel may be leached in small amounts, so that the present invention may be more suitably applied when it is difficult to separate iron and nickel.

The nickel-iron-containing raw material to which the present invention can be applied is not particularly limited, and any nickel-iron-containing raw material can be applied as long as it contains nickel and iron, and preferably nickel ore, for example, nickel such as limonite and sapolite Ore. 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 ore, the ore may be subjected to a pretreatment step as necessary in order to effectively reduce the ore in the reduction step described below. Such a pretreatment step includes a drying step, a pulverizing step and a baking step. Hereinafter, the pretreatment step will be described in detail.

Nickel ore, which is a raw material used for nickel recovery, preferably uses atomized powder to perform an efficient reduction process. Therefore, it is preferable to grind nickel ore into predetermined particle size range previously.

At this time, the nickel ore generally contains about 30 to 40% of the number of adhered water and about 10% of the crystal water. When the nickel ore is pulverized, the grinding efficiency is lowered. In the case of pulverizing the nickel ore after firing, there is a risk of causing a load on the crushing equipment due to high heat. Therefore, it is preferable to dry the nickel ore before pulverizing the nickel ore into fine particles. There is no particular limitation on the condition that the adhesion water in the nickel ore can be evaporated in performing the drying process for the nickel ore. For example, the heating may be performed at a temperature ranging from 100 to 200 ° C.

After drying the nickel ore may be subjected to a step of grinding for the reduction efficiency of the nickel ore. In the case of the above-mentioned grinding | pulverization, it is not necessarily limited to this, It is preferable to grind | pulverize the particle size of nickel ore to 1 mm or less for the reduction and leaching efficiency improvement. The lower the particle size of the pulverized ore is, the smaller the particle size of the pulverized ore is, so that the reduction and leaching efficiency can be improved. However, 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 a plurality of times, and it is preferable to use a powder of 10 μm or more.

On the other hand, the crystal water contained in the nickel iron-containing raw material is not removed in the drying process. The crystallized water is released as the water of crystallization contained in the ore in the reduction process during the reduction reaction of the nickel iron-containing raw material, this water is to act as a factor to slow the reduction reaction to reduce the reaction efficiency. Therefore, it is preferable to perform the reduction treatment after removing the crystal water. In order to remove such crystallized water, it is preferable to fire a nickel iron containing raw material.

Nickel ore, especially limonite ore, has the property of releasing crystal water at a temperature of about 250 ° C. or more. Therefore, by calcining the nickel iron-containing raw material powder obtained in the grinding step in the range of 250-450 ° C., the crystal water contained in the raw material can be effectively removed.

Since the calcined ore calcined to remove the crystal water in the ore has sensible heat according to the calcining temperature at the time of calcining, it is possible to save energy required for heating to the temperature for reduction if it is directly put into the reduction process without cooling. .

In one embodiment of the invention, the reduction is preferably carried out divided into a preliminary reduction and a main reduction step. In this way, the energy consumption can be reduced by reducing the nickel ore by the main reduction step after the preliminary reduction step. In particular, in the preliminary reduction step, the reducing gas can be used as a low-cost hydrogen-containing mixed gas, thereby reducing the cost of the process. Can be reduced.

The reduction reaction when hydrogen is used as the reducing gas for the calcined nickel ore can be expressed by the following equation (1).

On the other hand, in the case of recovering ferronickel by wet smelting from nickel ore, such reduced ore is applied to a process of leaching nickel ions by dissolving with an acid and of depositing and recovering nickel from the leached nickel ions as a metal. Also used for.

Therefore, hereinafter, the preliminary reduction and main reduction processes will be described separately by dividing into reduced leaching or reducing ore.

First, the preliminary reduction step will be described.

The reduced nickel ore leaches nickel and iron into ions from the ore using an acid such as hydrochloric acid or sulfuric acid, and precipitates it to be recovered as ferronickel metal. In the leaching process, for example, the reaction of leaching the nickel reduced ore using hydrochloric acid can be represented by the following reaction formula (2).

As can be seen from the above formula (2), 4 mol of hydrogen is required to reduce the nickel ore, and 3 mol of hydrogen can be recovered by the leaching reaction of the reduced ore. At this time, one mole of hydrogen is not recovered, but Fe ₂ O ₃ contained in the raw material nickel ore is trivalent iron and is reduced to reducing ore such as Fe ₃ O ₄ and FeO before being reduced to metal to generate water.

That is, when the reduction reaction of Fe ₂ O _{3 in} the reaction formula (1) is represented by the reaction formula can be expressed as the following formula (3).

On the other hand, if the formula (3) is divided again by the reduction step, it can be expressed as the following reaction formula (4) to (6).

As such, the metal Fe is generated by the reaction formula (6), and hydrogen is generated during the leaching reaction with an acid. However, according to the reaction formulas (4) and (5), the oxide containing divalent Fe is leached by iron, but no hydrogen gas is produced.

Therefore, since hydrogen recovery is not possible during the leaching reaction in the reactions of the reaction formulas (4) and (5), the preliminary reduction may be performed using a low-cost mixed reducing gas containing hydrogen, thereby reducing the use of expensive hydrogen-containing gas. desirable. As such a low-cost hydrogen-containing gas, for example, COG (Cokes Oven Gas, containing 50% or more of hydrogen) generated in an iron ore smelting process or hydrogen-containing gas (containing 65% or more of hydrogen) generated in a methane hydrogen reforming reaction can be used. Can be.

In addition, such a preliminary reduction is preferable because it can be carried out at a relatively low temperature compared to the reduction temperature of the main reduction process. The preliminary reduction may be performed by introducing a reducing gas into the furnace at 450-600 ° C. in the production of reduced ore for leaching. On the other hand, in preparing the reduced ore for precipitation can be carried out by introducing a reducing gas into the furnace in the temperature range of 500 to 700 ℃. Thereby, iron can be reduced at a reduction rate of about 30% or more.

A main reduction process is performed on the reduced light that has undergone such preliminary reduction. At this time, the reducing gas used in the main reduction may be hydrogen, nitrogen gas may be added to the hydrogen reduction gas for the system purge. In the case where hydrogen is used as the reducing gas, hydrogen is generated during the nickel recovery process, in particular, in the leaching of nickel, which is preferable because hydrogen can be recovered and recycled into the reducing gas.

In the main reduction step, the production of reduced ore for leaching will first be described.

First, in preparing the leaching ore, the main reduction process may be performed using a high purity hydrogen-containing gas at 600-950 ℃. When the main reduction process is carried out below 600 ° C, it is difficult to obtain iron reduction rate of 50% or more. In terms of thermodynamics, nickel is easier to reduce than iron, and as a result of many reduction experiments on nickel ore, when the reduction rate of iron in nickel ore exceeds 50%, nickel in nickel ore proceeds to be reduced more easily than iron, so it becomes a metal. , Nickel may be reduced to the metal. Therefore, the nickel metal can be dissolved when the acid leaching process is performed to ensure a good leaching rate of nickel. Therefore, in preparing the leaching ore, it is preferable to perform the main reduction reaction of nickel ore at a temperature of 600 ° C or higher.

On the other hand, when the reduction of the nickel ore is performed at a temperature exceeding 950 ℃, it is difficult to expect further increase in the nickel leaching rate, rather it may lead to a decrease in nickel leaching rate. In other words, when the reduction process is performed at a high temperature, it is possible to obtain a higher reduction rate of iron, but the activity of the reduced ore tends to be lowered, which may lower the leaching rate of nickel. Furthermore, it is more preferable not to exceed 950 degreeC also from an energy efficiency viewpoint.

As such, in preparing the leaching ore, it is preferable to carry out at a temperature range of 600 to 950 ° C. such that the iron reduction rate reaches 50-92%. When the reduced nickel reduced ore is leached with hydrochloric acid, nickel in the ore can be dissolved into ions at a recovery rate of 90% or more within 2 hours.

On the other hand, in the case of recovering nickel by wet smelting from nickel ore, the reduced light of nickel ore is also applied to a nickel precipitation process as in the following formula (7).

The principle of Scheme (7) is due to the natural potential difference between iron and nickel, and occurs by a battery reaction as shown in the following scheme.

Anodic Reaction:

Cathodic Reaction:

Over all Reaction:

That is, a battery is formed by a natural potential difference between nickel in the ion-containing solution of iron and nickel and iron in the reducing raw material, and a dissolution reaction by oxidation of iron proceeds at the anode site of the reducing raw material, and at the negative electrode site of the reducing raw material. The reaction in which nickel ions in the ion-containing solution of iron and nickel are reduced to precipitate proceeds.

As can be seen from the reaction formula (7), it can be seen that the reduced ore used for the precipitation is advantageous to substitute and precipitate nickel ions dissolved by an acid in the leaching process only when iron is present as a metal.

In the production of such reduced ore for precipitation, if the iron reduction rate is less than 70% in the temperature of the main reduction reaction, the recovery rate of nickel metal due to substitutional precipitation is sharply lowered. It is preferable to adjust so that. On the other hand, when the iron reduction rate exceeds 96%, the recovery rate of nickel due to substitution precipitation is insignificant, and sintering, etc., may occur severely, which may lower the precipitation efficiency of nickel. Therefore, the reduction rate should be 96% or less. .

In order to obtain a reduced ore having the iron reduction rate in the above range, it is preferable to perform the main reduction reaction in the pre-reduced nickel light in the temperature range of 700 to 950 ℃. That is, when the main reduction reaction is carried out at a temperature of less than 700 ℃, only iron reduction of less than 70% is obtained, the poor recovery of nickel precipitation is obtained, the production rate of the target ferronickel metal is low, the main at 1050 ℃ When the reduction reaction is performed, a high reduction rate is obtained, but the precipitation efficiency is relatively lower than that of 950 ° C. On the other hand, if the reduction at a temperature exceeding 1050 ℃ the reduction rate is increased, but the precipitation rate does not increase any more, it is preferable to reduce at 1050 ℃ or less during the production of reduced ore for precipitation.

Thus, after reducing nickel ore by the method for obtaining a leaching ore, the obtained leaching ore is slurried in an anoxic state, and hydrochloric acid or sulfuric acid is added to the slurry obtained as described in the reaction formula (2). The same leaching reaction can be carried out.

When the reduced metal is present in the aqueous solution during the acid dissolution reaction, the Oxygen Reduction Potential (ORP) shows a-value. When the metal is completely dissolved in the acid, the ORP becomes 0 and then changes to a + value. 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 nickel ion-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-ion-containing solution can be obtained by separating with a solid-liquid separator such as a filter press or a decanter.

Next, a step of depositing ions of iron and nickel dissolved in the reaction of formula (7) in the ion-containing solution of iron and nickel as a metal. Precipitation of the iron and nickel ions may be performed by inputting the reduced ore for precipitation obtained according to the method for producing the reduced ore for the precipitation.

The precipitation ore may be used in the range of 10 to 40% by weight relative to the total weight of the raw material used in the entire ferronickel recovery process, that is, the total weight of the leaching reducing material and the precipitation reducing material, but is not limited thereto. It is not.

Example

Hereinafter, the present invention will be described in detail with reference to Examples. The following examples relate to an example of the present invention, but the present invention is not limited thereto.

Example 1

Limonite nickel ore containing 1% by weight of nickel and 29% by weight of iron was kept at an ore temperature of about 150 ° C. for 1 hour using a rotary kiln to remove moisture adhered to the ore, and then crushed by a super mill to average. A powder having a particle size of 800 µm was obtained.

The crushed ore was put into a calcination furnace maintained at 300 ° C. and calcined for 1 hour to remove crystal water.

The calcined nickel ore was discharged from the kiln and immediately introduced into a rotary kiln reduction furnace where oxygen was blocked, followed by preliminary reduction reaction at 550 ° C. for 1 hour by injecting hydrogen gas three times as many moles of iron as hydrogen. Was performed.

At this time, the reducing gas includes a COG gas containing 51% by volume of hydrogen as a preliminary reducing gas, an LNG reforming gas containing 65% by volume of hydrogen, and a gas containing 29% by volume and 71% by volume of nitrogen and hydrogen. Each was used.

At this time, the reduction rate of reduced ore was investigated 1 hour after the start of the preliminary reduction. As a result, it was confirmed that the iron reduction rate is 30%, 33% and 35%, respectively.

From this, it can be seen that the iron reduction rate is somewhat higher when using a gas mixed with nitrogen and hydrogen having a high hydrogen content. However, even when using COG gas and LNG gas, it can be seen that the iron reduction rate of 30% or more is obtained. Even when using a low-grade reducing gas, it was confirmed that the effect to obtain by preliminary reduction is sufficiently achieved.

Example 2

Nickel ore was pulverized in the same manner and in the same manner as in Example 1 to obtain nickel ore powder having an average particle size of 800 µm and fired.

When the calcined nickel light is discharged from the kiln and immediately put into the rotary kiln reduction furnace in an anoxic state, when a mixed gas of nitrogen and hydrogen of Example 1 mixed at 29% by volume and 71% by volume is injected as a reducing gas. In the same manner as in the pre-reduction reaction for 1 hour at 550 ℃.

The preliminarily reduced reduced ore was continuously injected with 99.99% high-purity hydrogen by injecting hydrogen gas twice the number of moles of iron, and the reducing temperature for leaching and the reduced ore for precipitation as shown in Table 1 were changed. Was prepared respectively.

The prepared reduced ore was cooled in an anoxic tank filled with nitrogen gas, and then 200 g of the reduced ore was mixed with 200 ml of water and slurried.

A solution of 1 liter was prepared by adding a concentration of 20% to the prepared slurry, followed by stirring at room temperature to perform a leaching reaction. After 40 minutes from the start of the leaching reaction, the redox potential was changed from-to + and the leaching reaction was stopped. Solid content was separated from the slurry to obtain a nickel solution.

Leaching reduced ore was leached with hydrochloric acid, and the leached nickel solution was analyzed by ICP to obtain a leaching recovery rate. The results are shown in Table 1.

On the other hand, the precipitated recovery ore obtained by varying the reduction temperature in an acid dissolution solution in which 4 g / liter of melted nickel was administered, and the nickel recovery rate was analyzed by ICP to determine the precipitation recovery rate. The results are shown in Table 1.

Usage Reduction temperature (캜) Reduction rate Nickel Leaching Recovery (%) Nickel precipitation recovery rate (%) Comparative Example 1 Leaching 550 35 56 Inventory 1 Leaching 650 55 90 Inventory 2 Leaching 750 74 96 Inventory 3 Leaching 850 88 98 Honorable 4 Leaching 950 92 96 Comparative Example 2 For precipitation 650 55 64 Inventory 5 For precipitation 750 74 91 Inventory 6 For precipitation 850 88 94 Honorable 7 For precipitation 950 92 95 Honors 8 For precipitation 1050 96 94

As can be seen from Table 1, in the case of Comparative Example 1, the reduction rate is low as 35% due to the low reduction temperature, thereby showing a low leaching recovery rate of nickel. On the other hand, in the case of Inventive Examples 1 to 4 shows a reduction result of more than 50%, the use of this reduced ore for leaching shows a high result of 90% or more nickel leaching recovery.

However, in the case of Inventive Example 4 having a reduction temperature of 950 ° C., although the reduction rate is higher than that of Inventive Example 3, nickel leaching recovery rate tends to be lowered. Therefore, nickel leaching recovery is expected to decrease when the reduction reaction is performed at a higher temperature.

On the other hand, as can be seen from Inventive Examples 5 to 8, when the reduction was reduced at a temperature of 700 ° C. or higher as the precipitation reducing light, a high Fe reduction rate of 70% or more was observed. When used in the precipitation reaction, it can be seen that the precipitation recovery rate of nickel shows a high result of 90% or more. However, as can be seen from Comparative Example 2, when the nickel temperature is reduced at a reduction temperature of less than 700 ° C, a low Fe reduction rate is shown, whereby a low nickel precipitation rate is obtained.

On the other hand, from the results of the invention example 8, as the reduction temperature for the production of the reduced ore for precipitation increases, the reduction rate increases, but the precipitation recovery rate of nickel tends to be lowered. When used as reduced ore, it can be seen that the precipitation recovery rate of nickel will decrease rather.

Claims (4)

A slurrying step of slurrying a leaching nickel reducing ore having a reduction rate of iron of 50 to 92% in water;
Leaching step of adding an acid to the slurry to dissolve nickel and iron from the leaching nickel reducing ore to obtain a nickel ion-containing solution; And
Precipitation step of depositing nickel ions in the nickel ion-containing solution by replacing the nickel ions in the nickel ions containing solution with metal iron of the deposited nickel reduction ore by depositing ferronickel with a reduction rate of 70-96% of iron in the nickel ion-containing solution.
A method for recovering ferronickel from nickel ore comprising a.
The method of claim 1, wherein the leaching nickel reduction ore is
A preliminary reduction step of preliminarily reducing the nickel ore with a hydrogen-containing gas at 450-600 ° C. to obtain a preliminary reduced ore; And
The main reduction step of reducing the preliminary reduced ore obtained in the preliminary reduction step with a hydrogen-containing gas at 600-950 ℃ to obtain a reduced ore
Method for recovering ferronickel from nickel ore reduced by a method comprising a.
The method of claim 1, wherein the nickel nickel ore for precipitation is
A preliminary reduction step of preliminarily reducing the nickel ore with a hydrogen-containing gas at 500-700 ° C .; And
The main reduction step of mainly reducing the preliminary reduction ore obtained in the preliminary reduction step with a hydrogen-containing gas at 700-1050 ℃
Method for recovering ferronickel from nickel ore reduced by a method comprising a.
4. The method of claim 2 or 3, wherein the hydrogen-containing gas in the preliminary reduction step is COG or LNG reforming gas or a mixture of nitrogen and hydrogen.