JPH09291317A - Treatment for waste material of iron-containing nickel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover nickel by adding a flux containing elements of specific contents to a waste material of iron-containing nickel and performing specific heat treatment. SOLUTION: This process is a treatment process for a waste material of iron-containing nickel, in which a flux containing silica, alumina, and lime is added to a waste material of iron-containing nickel and the resultant mixture is heated and melted under an inert-gas atmosphere, and then, oxygen is introduced and iron as impurity is passed in the form of oxide into a slag to separate iron and recover nickel. Further, this process is a treatment process where a flux, in which the contents of the above silica, alumina, and lime are regulated to 55-70wt.%, >=20wt.%, and 2-10wt.%, respectmvely, is used. Further, this process is a treatment process described in either of the above processes, in which the waste material of iron-containing nickel is composed of an iron-containing nickel-cobalt alloy or nickel-hydrogen battery waste.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method for recovering nickel and cobalt by easily and efficiently separating and removing iron from iron-containing nickel-cobalt waste material such as hydrogen storage alloy represented by nickel-hydrogen battery waste. Regarding

[0002]

2. Description of the Related Art Nickel-cobalt alloys are used as a hydrogen storage material in nickel-hydrogen batteries (Ni-MH batteries), etc. Complete Ni-MH batteries contain a significant proportion of nickel and cobalt. For this reason, in order to effectively utilize resources and protect the environment, it is required to efficiently recover and reuse nickel and cobalt from these wastes.

Conventionally, as a method of recovering nickel and the like,
(A) JP-A 1-228586 discloses that Ni-Cd battery waste is put into pig iron or steel held in a molten state to recover metallic cadmium from volatile matter, while nickel is replaced with ferronickel (F
(e-Ni alloy). Further, (b) JP-A-55-158238 discloses that pickling sludge containing heavy metals, plating sludge, scale, waste containing heavy metals such as dust, or waste containing light metals such as alumina by alumina cement. There is disclosed a method in which heavy metals are recovered as alloys and used as raw materials for steelmaking by solidifying and reducing smelting into briquettes, while light metals are slagged and recovered as alumina cement and alumina raw materials.

However, in any of these methods, nickel is ferronickel or C-Si-Ni-Cr containing a large amount of iron.
Therefore, it is not suitable as a method for treating nickel-hydrogen battery waste, which is limited to steelmaking raw materials and the like and is required to be separated from iron and nickel.

[0005]

DISCLOSURE OF THE INVENTION The present invention has solved the above problems in the conventional method for treating nickel-containing waste,
An object of the present invention is to provide a method for easily and efficiently separating iron from iron-containing nickel waste represented by nickel-hydrogen battery waste and recovering Ni of relatively high purity.

[0006]

Means for Solving the Problems According to the present invention, (1) a flux containing silica, alumina and lime is added to a nickel waste material containing iron, and the mixture is heated and melted in an inert gas atmosphere, and oxygen is added to this. It is a method for treating an iron-containing nickel waste material, which is characterized in that iron is separated and nickel is recovered by introducing and transferring iron as an oxide into a slag as an oxide.

In the above treatment method, (2) the silica content is 55 to
The above-mentioned (1) using a flux comprising 70% by weight, 2-10% by weight of lime and 20% by weight or more of alumina.
(3) the iron-containing nickel waste material is an iron-containing nickel-cobalt alloy, (4) the iron-containing nickel waste material is a nickel-hydrogen battery waste The processing method according to any one of (1) to (3) above is included.

[0008]

[Detailed Description] Hereinafter, the present invention will be specifically described with reference to Examples. In the following description,% is% by weight unless otherwise indicated.

According to the treatment method of the present invention, a flux containing silica, alumina and lime is added to nickel-containing waste material containing iron, the mixture is heated and melted in an inert gas atmosphere, and oxygen is introduced into this to remove impurities. It is a method of separating iron and recovering nickel by transferring iron to the slag as an oxide. Examples of the nickel waste material containing iron include nickel-hydrogen battery waste containing a large amount of nickel-cobalt alloy known as a hydrogen storage alloy, as described above.

As the flux, a ternary flux composed of silica (SiO ₂ ) -alumina (Al ₂ O ₃ ) -lime (CaO) is used. In addition to being inexpensive, this flux has good separability from iron in terms of specific gravity and viscosity, and metal (Ni, C
Good separation of o) and slag. In addition, since an alumina component is contained, corrosion and erosion of an alumina container are prevented, so that there is an advantage that the container can be used safely.

As shown in Examples and Comparative Examples described later, the amount ratio of each component is such that the silica content is 55 to 70% by weight, the lime content is 2 to 10% by weight, and the alumina content is 20% by weight or more. Is preferred. When the silica content is less than 55% by weight, the effect of separating iron is reduced, and especially when the silica content is about 10% by weight, the residual iron amount becomes remarkable. Further, when the silica content exceeds 70% by weight, the alumina content and the lime content are relatively small, and when the lime content is less than 2% by weight, the effect of separating iron becomes low. On the other hand, when the lime content exceeds 15% by weight, the silica content and the alumina content are relatively reduced, and the iron separation effect is reduced, so 10% by weight is suitable for the lime content. Further, when the alumina content is about 10% by weight, the effect of separating iron is also low. Therefore, the alumina content is preferably 20% by weight or more. On the other hand, when the alumina content is about 85% by weight, the silica content or the lime content is relatively lower than a predetermined amount ratio, the separation effect of iron decreases, and the recovery rate of nickel and the like also decreases, which is not preferable.

The flux may be a mixture of silica, alumina and lime so that the silica content, the alumina content and the lime content may be in the above amount ratio, and these components may be adjusted to the above amount ratio in terms of oxide. You may use the silicate containing. The amount of flux to be added depends on the composition of the nickel waste material, but is generally 20 to 100 parts by weight of the nickel waste material.
35 parts by weight, preferably 25-30 parts by weight are suitable. If the amount of the flux added is less than the above range, the effect of separating iron will not be sufficient, and if the amount of the flux added exceeds the above range, the treatment cost will be wasted against the nickel recovery efficiency.

A mixture of iron-containing nickel waste material and the above flux is heated in an inert gas atmosphere to a temperature not lower than the melting point of nickel, preferably 1500 to 1530 ° C., and volatile components such as hydrogen gas generated from the waste material are converted into an inert gas. It melts while being driven out. As a result of this heating, a slag is formed on the surface of the molten material, which is composed of a portion of the nickel waste material in which the metal content has been melted, and the waste material and the silica content and lime content of the flux.

By heating and melting under an inert gas atmosphere, hydrogen gas can be safely expelled from the system. When heated in the air without using an inert gas, hydrogen gas generated may react violently with oxygen and explode. Further, if oxygen remains, nickel and cobalt are oxidized and become slag loss, which is not preferable.

After heating and melting in an inert gas atmosphere,
By introducing oxygen into this melt, iron and rare earth metals in the melt,
Impurities such as aluminum and manganese are oxidized, and this oxide is separated from the melt by transferring to slag.
The introduction of oxygen is performed after the processing waste material is dissolved. At the end of melting of the treated waste material, it is empirically possible to grasp it by inserting an alumina test rod into the melt and feeling it, but in general,
After reaching the set melting temperature, heating may be further performed for about 60 minutes.

The introduction of oxygen may be performed by blowing air, and any method such as a top blowing method through a lance provided on the upper side of the melt or a bottom blowing method in which the furnace bottom is blown into the melt may be used. The amount of air blown into the melt is preferably about equimolar to the impurities in the melt in terms of oxygen. When the amount of air is less than this, the oxidation of impurities such as iron becomes insufficient and remains in the melt. Further, if the amount of air is larger than this, the oxidation of nickel or cobalt is promoted and slag loss occurs, which is not preferable.

As described above, since the impurities in the melt are oxidized and absorbed by the slag floating on the surface of the melt, the slag is removed from the surface of the melt and separated from the metal content of the melt.
Alternatively, the metal melt may be extracted from the bottom of the melting furnace or the melting container leaving the slag. The metal component separated from the slag and recovered is cooled, washed if necessary, and reused.

As described above, the treatment method of the present invention is a method capable of efficiently and easily separating iron from an iron-containing nickel waste material to recover nickel, and thus is known as a hydrogen storage material. It is useful as a method for treating nickel-hydrogen battery waste containing a large amount of nickel-cobalt alloy. This hydrogen storage alloy is used as a negative electrode active material for nickel-hydrogen batteries, and the battery waste material includes
For example, Ni: about 34%, Co: about 3.3%, Fe: about 25%, Al: about 0.5.
%, Mn: Approximately 3.2% of nickel and cobalt, and iron and other metallic impurities are contained.

In order to apply the method of the present invention to the above-mentioned waste battery material, first, a part of the outer can of the waste battery material is opened or cut so that hydrogen gas generated during heating is discharged to the outside of the can. 20 to 35% by weight of the above flux is added to a battery waste material and heated under an inert gas atmosphere to melt the generated hydrogen gas while expelling the generated hydrogen gas with the inert gas. After melting, the nickel-cobalt alloy can be recovered by cooling and removing the slag.

The above-mentioned method for treating battery waste material is extremely simple and does not require the conventional pretreatment such as crushing the entire battery waste material or separating the outer can from the electrode.
Iron-free nickel-cobalt alloys can be recovered.

[0021]

Hereinafter, examples of the present invention and comparative examples will be described. In addition, these are illustrations and do not limit the scope of the invention.

Example 1 25 g of Ni-hydrogen battery waste (Ni: 3) discarded from a commercial product
About 3.9%, Co: 3.3%, Fe: 25.3%, Al: 0.5%, Mn: 3.2%), part of the outer can is opened, and 25% of the amount of waste battery charged
Was added to a crucible made of alumina, charged into a high-temperature heating furnace, and heated and melted at 1500 ° C. for 1 hour in an Ar gas atmosphere. After melting, blow 10.8 liters of air corresponding to 0.1 mol amount of oxygen in the waste battery at a rate of 90 cc / min to the iron content (corresponding to 0.1 mol) in the waste battery, and leave it still. After cooling, except for slag, 8.8
g of Ni-Co alloy was recovered. The composition of the flux and the recovery results are shown in Table 1. In addition, Table 2 shows the amount of impurities in the recovered Ni-Co alloy.

Examples 2 and 3 A Ni-Co alloy was recovered in the same manner as in Example 1 except that the composition of the flux was changed as shown in Table 1. The results are shown in Table 1. In addition, Table 2 shows the amount of impurities in the recovered Ni-Co alloy.

Comparative Examples 1 to 7 Ni-Co alloys were recovered in the same manner as in Example 1 except that the fluxing agents having the compositions shown in Table 1 were used. In Comparative Example 1, when the flux does not contain lime, Comparative Examples 2 and 3 have too little or too much lime, Comparative Example 4 uses calcium fluoride instead of lime, and Comparative Example 5 uses silica. When the amount is excessive, Comparative Example 6
Indicates the case where the alumina content is excessive. In Comparative Example 7, the Ni-Co alloy was recovered without using the flux. The results and the like are shown in Table 1, and the amount of impurities in the recovered Ni-Co alloy is shown in Table 2.

As shown in Tables 1 and 2, according to the treatment method of the present invention, 90% or more of the amount of Ni-Co in the waste material of nickel-hydrogen battery can be recovered. The content of iron in the recovered Ni-Co alloy is 1.2% by weight or less, and the contents of aluminum, manganese, and rare earth elements are all 0.1% by weight or less.

On the other hand, in each of the comparative examples, the Ni—Co alloy recovery rate is in the range of 80% to 50%, which is significantly low. Moreover, the content of iron in the recovered Ni-Co alloy was about 3 in the above example.
It is twice to 30 times, and the amount of other impurities is considerably large.

Among them, in Comparative Example 1 in which the flux containing no lime was used, the recovery rate of the Ni—Co alloy was as low as 81% and the iron content was as high as 4%. Further, Comparative Example 2 in which the lime content is too small is similar to Comparative Example 1. On the other hand, in Comparative Example 3 in which the lime content is excessive, the recovery rate of the Ni—Co alloy is higher than that in the other Comparative Examples, and the iron content is also reduced, but it is still about three times as large as that in the Examples. Comparative Example 4 in which calcium fluoride was used instead of lime
Has a significantly lower Ni-Co alloy recovery rate and an iron content of 1
Remarkably high at 4% level. In Comparative Example 4, corrosion of the alumina crucible used was observed.

Further, in Comparative Example 5 in which the amount of silica is excessive and the amount of alumina is insufficient, the viscosity of the melt is so high that the separation of metal and slag is poor, the recovery rate is lowered, and the effect of separating impurities such as iron is also low. . Comparative Example 6 in which the alumina content was excessive,
Since unmelted alumina remains in part and proper slag is not formed, separation and removal of impurities are insufficient and the recovery rate is low. Further, in Comparative Example 7 in which no flux was used, the metal and the oxide were mixed, and the impurities could hardly be separated and removed.

[0029]

[0030]

[0031]

As described above, according to the treatment method of the present invention, nickel can be recovered from iron-containing nickel waste material by efficiently and easily separating and removing impurities such as iron. Therefore, it is useful as a method for treating nickel-hydrogen battery waste containing a large amount of nickel-cobalt alloy known as a hydrogen storage material.

Claims (4)

[Claims] 1. A flux containing silica, alumina and lime is added to nickel-containing waste material containing iron, the mixture is heated and melted in an inert gas atmosphere, and oxygen is introduced into this to convert iron as an oxide into an oxide. A method for treating an iron-containing nickel waste material, characterized in that iron is separated and nickel is recovered by shifting to slag. 2. The processing method according to claim 1, wherein a flux having a silica content of 55 to 70% by weight, a lime content of 2 to 10% by weight, and an alumina content of 20% by weight or more is used. 3. The processing method according to claim 1, wherein the iron-containing nickel waste material is an iron-containing nickel-cobalt alloy. 4. The processing method according to claim 1, wherein the iron-containing nickel waste material is a nickel-hydrogen battery waste material.