KR20150131394A - Method for collecting valuable metal - Google Patents

Abstract

The present invention relates to a method for recovering a cyanide waste liquid which is capable of treating a medium to high-concentration cyanide waste liquid at a low cost and easily, and recovering a so-called valuable metal such as a noble metal, a rare earth element and other metals remaining in the waste liquid, ≪ / RTI > The present invention relates to a method for producing a waste solution (100), comprising concentrating a concentrate (101) of a waste solution (100) containing a cyanide compound, inorganic carbonate and a valuable metal at 400 to 650 캜, And recovering the valuable metal from the fired residue (102) after separation.

Description

[0001] METHOD FOR COLLECTING VALUABLE METAL [0002]

The present invention relates to a method for recovering valuable metals.

So-called valuable metals such as noble metals, rare earth elements and other metals are industrially very useful materials and are used in a wide range of fields. For example, an electrolytic plating method or an electroless plating method using gold is widely known, and a cyanide gold plating liquid having excellent stability in a liquid as a gold supply source has conventionally been used as the plating liquid.

However, since the cyanide compound has strong toxicity and the concentration of the cyanide compound in the plating solution as described above is generally in a medium to high concentration, it is necessary to thoroughly treat the waste solution after plating. On the other hand, a valuable metal, which is a valuable material, is required to be recovered as much as possible from the waste solution after plating to be reused.

Conventionally, as a method of treating a waste liquid (medium to high concentration cyanide waste liquid) containing a cyanide compound in a medium to high concentration, for example, an in-spray method is known. Here, the medium concentration means that the concentration of the cyanide compound in the waste solution is, for example, 100 mg / L or more and less than 1000 mg / L. The high concentration means that the concentration of the cyanide compound in the waste solution is, for example, 1000 mg / L or more.

The furnace spraying method is a method of decomposing a cyanide compound by spraying the waste liquid in a furnace at a high temperature exceeding 1000 캜. However, this method is disadvantageous in that it is expensive, and the inorganic carbonate such as alkali metal carbonate or alkaline earth metal carbonate which is a heat-fusible salt is melted and is deposited in the furnace to break down the furnace, There is a problem.

It is also known to treat a waste solution (low-concentration cyanide waste solution) containing a cyanide compound at a low concentration. Here, the low concentration means that the concentration of the cyan compound is, for example, less than 100 mg / L.

For example, Patent Document 1 discloses an alkali chlorine method in which sodium hydroxide is added to a low-concentration cyanide waste solution, sodium hypochlorite is added while the pH is adjusted to 10 to 11, and a cyanide compound is decomposed to nitrogen. However, if it is desired to recover valuable metals from a medium to high-concentration cyanide waste solution by the alkali chlorine method, a large amount of chemicals are required to be used and the sieve body with the treated waste liquid becomes large, accompanied by remarkable heat generation due to heat of reaction, There is a problem that harmful chlorine is generated.

In addition, a method of thermally hydrolyzing at a high temperature and a high pressure (see, for example, Patent Document 2), and an ozone oxidation method using an oxidizing power of ozone gas (see, for example, Patent Document 3). The former method can not sufficiently decompose the cyanide compound, and the latter method has a problem of high cost.

Japanese Patent Laid-Open No. 50-118962 Japanese Patent Laid-Open No. 1-194997 Japanese Patent Laid-Open No. 2006-341229

Accordingly, an object of the present invention is to provide a process for producing a cyanide-containing waste liquid, which is capable of easily and efficiently treating cyanide waste liquid of medium to high concentration at a low cost and which is capable of treating a so-called valuable metal such as noble metal, rare earth element, Which can be recovered in a sufficiently large amount.

The present inventors have found that the above problems can be solved by carrying out a step of calcining a concentrate of a waste liquid containing a cyanide compound, an inorganic carbonate and a valuable metal at a relatively low temperature and separating cyanide from the waste liquid as cyanogen gas , Thereby completing the present invention.

That is, the present invention is as follows.

1. A process for recovering a valuable metal from a calcined residue after calcining a concentrate of a waste solution containing a cyanide compound, an inorganic carbonate and a valuable metal at 400 to 650 DEG C, separating cyanide from the concentrate of the waste solution as cyanogen Containing metal recovery method.

2. The method of recovering valuable metals according to 1 above, comprising a step of recovering liquid metal in liquid form.

3. The method of recovering valuable metals according to 1 or 2 above, wherein the inorganic carbonate is an alkali metal carbonate and / or an alkaline earth metal carbonate.

4. The method according to any one of items 1 to 3 above, wherein the concentration of the cyanide compound and the concentration of carbonate carbonate in the inorganic carbonate are in the range of 2 to 200 g / kg, 20 g / kg or more and less than 1000 g / Metal recovery method.

In the present invention, the concentrate of the waste solution containing the cyanide compound, the inorganic carbonate and the valuable metal is calcined at a relatively low temperature of 400 to 650 占 폚 to separate the cyanide compound as the cyanide gas and the inorganic carbonate as the heat- It does not melt and does not corrode the furnace. In addition, the occurrence of alkali fumes is also prevented, and safety is enhanced. Further, since the firing temperature is low, a low cost is achieved. The fired residue from which the cyanide compound is separated has low toxicity, and subsequent metal recovery is easy. Further, according to the mode in which the separated cyan gas is further burned, the cyan gas can be decomposed into water, carbon dioxide, and nitrogen, thereby facilitating further processing of the exhaust gas.

1 is a process diagram for explaining a preferred embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

The waste liquid used in the present invention contains a cyanide compound, an inorganic carbonate and a valuable metal. Examples of the waste liquid include noble metals such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir) and ruthenium (Ru), rare earth metals such as scandium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Sn), lead (Pb), zinc (Zn), copper (Zn), and the like, which are other metals (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium A waste liquid containing a valuable metal such as copper (Cu), nickel (Ni), cobalt (Co), thallium (TI), indium (In) or gallium (Ga) It is preferably a waste liquid containing gold.

For example, those derived from a plating solution in an electrolytic plating method using a noble metal and an electroless plating method. For example, known plating solutions such as Au-Ni, Pd-Ni and Au-Pd-Ni are known.

The waste solution in the present invention is not limited to the above-mentioned form, and examples thereof include a cyanide waste liquid generated by a precious metal recycling, a surface treatment, an electric / electronic component manufacturing, and a pharmaceutical or agricultural chemical manufacturing industry. Hereinafter, a waste solution of a plating solution containing gold (hereinafter referred to as a gold plating waste solution) is taken as an example.

The concentration of the cyanide compound in the gold plating waste solution is generally in a medium to high concentration range. When the gold plating waste solution is processed by employing the conventional in-spraying method as described above, high temperature heating is required, There is a problem that the furnace carbonate (heat-melting salt) adheres to the furnace to break the furnace, and the recovery of the gold becomes impossible.

Further, the inorganic carbonate in the gold plating waste liquid is derived from an additive suitably added to the plating liquid; During the operation of electroplating, a part of the CN is anodized and decomposed into carbonate ions; For example, carbon dioxide in the air is absorbed and carbonate ions are built up. The concentration thereof is, for example, 1 to 100 g / L as carbonate ion.

Accordingly, in the present invention, the concentrate of the waste solution containing a cyanide compound, an inorganic carbonate and a valuable metal is sintered at a relatively low temperature of 400 to 650 DEG C, and a step of separating the cyanide compound as a cyanide gas is performed, It is.

First, in the present invention, a concentrate of a waste solution containing a cyanide compound, an inorganic carbonate and a valuable metal is prepared. Examples of the method for concentrating the waste liquid include a method of evaporating and drying at 100 to 110 占 폚, and a method of heating or drying in a vapor dryer in an evaporation dish. Concentration of the waste liquid to a solid such as a powder or bulk by these various means is preferable because the subsequent treatment can be facilitated.

In the present invention, even when the concentration of the cyan compound in the waste solution concentrate is 2 g / kg or more, it is possible to efficiently separate the cyanide compound as cyanogen gas, preferably 2 to 200 g / kg, more preferably 5 to 200 g / Kg. ≪ / RTI >

The inorganic carbonate may be preferably a waste liquid concentrate containing an alkali metal carbonate and / or an alkaline earth metal carbonate, more preferably a waste liquid concentrate containing an alkali metal carbonate having a melting point of 700 to 1000 ° C .

The inorganic carbonate in the waste liquid concentrate can efficiently separate the cyanide compound as a cyanide gas even if the concentration in terms of carbonate ion is a high concentration of 20 g / kg or more, preferably 20 g / kg or more and less than 1,000 g / kg can do.

Further, even if the concentration of the valuable metal in the waste liquid concentrate is not more than 1000 mg / kg, the cyanide compound can be efficiently separated as cyanogen gas to efficiently recover the valuable metal, and is preferably carried out at 10 mg / kg or more can do.

The concentrate is then calcined at 400-650 占 폚. The firing can be carried out under hermetic conditions, under atmospheric pressure, under pressure or under reduced pressure (for example, from -60 to -10 Pa). The heating rate is, for example, 1 to 10 占 폚 / min, preferably 1 to 5 占 폚 / min. The high-temperature holding time of the firing is, for example, 30 to 120 minutes.

By this firing, the organic matter contained in the waste liquid is burned to generate carbon dioxide and water. The cyanide compound reacts with this carbon dioxide and water and is separated as cyanogen gas, for example, by the following reaction formula (1). Further, in the case of forming a complex of a cyanine with a valuable metal such as gold, a part or the whole thereof is decomposed and separated into a valuable metal and a cyanide gas by thermal decomposition and separated.

Gold and the like form a complex with cyan, it is difficult to decompose at low temperatures. Therefore, when the temperature is lower than 400 ° C, it is difficult to separate the cyanide complex from a valuable metal such as gold and cyanide, . If the temperature is higher than 650 ° C, there is a problem that the alkali metal carbonate is melted and adhered to the furnace so that the furnace is broken and the valuable metal can not be recovered.

The separation as cyanide gas in the present invention means separation by cyanogen gas generated by the decomposition of the waste liquid concentrate produced by the decomposition of the cyanide or decomposition of the generated cyanide gas by decomposition or combustion of carbon dioxide and nitrogen Lt; RTI ID = 0.0 > a < / RTI > waste liquid concentrate.

[Formula 1]

Generally, the decomposition of cyan is initiated at about 600 to 850 DEG C, but in the present invention, cyanide gas can be produced by firing the concentrate at a relatively low temperature, and the cyanide compound can be removed from the concentrate.

In the above Reaction Scheme 1, NaCN or KCN usually contained in the gold plating waste solution readily reacts with light, heat or CO ₂ to generate HCN. In the above-described calcination temperature range, these reactions are promoted and the production of HCN is increased.

Subsequently, in the present invention, after the cyanide is separated from the concentrate of the waste liquid as cyanide gas, the inorganic carbonate is not subjected to hard sintering by thermal melting, but the liquid metal is recovered from the soft and porous sintered residue. At this time, since the inorganic residue of the inorganic carbonate is in a fine powder state without sintering due to thermal melting, the inorganic carbonate has high solubility in water and is excellent in liquid permeability, and the inorganic carbonate is washed with water, It is suitable for liquid phase recovery. As a method for recovering the liquid phase of the valuable metal, for example, there is a method of dissolving in water and reducing with a reducing agent.

The cyanide gas in the separated exhaust gas 106 can be collected by alkali and oxidatively decomposed by a known alkali chlorine method, ozone or electrolysis method, or can be treated by burning at a high temperature of 800 DEG C or higher. In the present invention, it is preferable to further include a step of burning at a high temperature of 800 DEG C or more so as to completely burn out the cyanide gas after the step of sintering to 400 to 650 DEG C described above.

The combustion temperature is, for example, preferably 800 to 950 占 폚. The heating rate is, for example, preferably 1 占 폚 / min to 10 占 폚 / min, more preferably 1 占 폚 / min to 5 占 폚 / min. The burning time is, for example, preferably 30 to 120 minutes after reaching the specified temperature. By this process, the cyan gas is decomposed into water, carbon dioxide and nitrogen, for example, by the following reaction formula 2, and the treatment of the exhaust gas becomes easy.

[Formula 2]

1 is a process for explaining a preferred embodiment of the present invention. In Fig. 1, the gold plating waste liquid 100 is evaporated to dryness, and a concentrate 101 is obtained. The obtained concentrate (101) is calcined at 400 to 650 占 폚 and separated into calcined residue (102) and cyanide (103).

The fired residue 102 is washed with water and separated into a water residue and a waste alkali 105. The washing with water at this time is carried out by adding water, preferably hot water, of about 5 to 10 times the mass of the fired residue 102 to the washing bath, and stirring them.

The washed washed residue 104 is calcined at 500 to 800 ° C for 1 to 4 hours, if necessary, after which gold is recovered by the method as described above. Since the waste alkali 105 has a low cyanide concentration, it can be detoxified by the conventional alkali chlorine method.

On the other hand, the cyan gas 103 is introduced into the combustion furnace, and is burned as described above to become the exhaust gas 106. The exhaust gas 106 is harmless by being cooled in a saturated water-vapor type quenching tower or a completely evaporated quenching tower by caustic alkali water, and collected by an electric dust collector, and is discharged into the air.

Example

Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited to the following examples.

[Example 1]

A gold plating waste solution having the following composition was prepared. Table 1 below shows the measurement results of the composition in the gold plating waste solution.

The gold plating waste solution was treated by the process shown in Fig. First, a gold plating waste solution (100) was used as an apparatus, and a concentric apparatus (101) was obtained by evaporating and drying at 110 DEG C using a rotary-circulation type evaporation apparatus. The concentrate 101 was subjected to quantitative analysis. The results are shown in Table 2 below.

Subsequently, 10 kg of the concentrate 101 was put into a rectangular firing container with a thickness of 10 cm, introduced into a firing furnace, and fired at 500 ° C. The firing was carried out under reduced pressure, and the rate of temperature rise was 3 ° C / min., And the firing time was 30 minutes after reaching 500 ° C. The obtained fired residue 102 was subjected to quantitative analysis. The results are shown in Table 3 below.

Subsequently, 200 g of the obtained fired residue 102 was taken and put in a water bath together with one liter of water, and the two were washed with water by stirring. The washed residue 104 obtained as an insoluble matter was calcined at 600 ° C under a reduced pressure (-10Pa) for 1 hour at a high temperature holding time, and then subjected to quantitative analysis. The results are shown in Table 4 below.

Subsequently, 9 mg of gold was recovered as a liquid by the method of dissolving the washed water residue 104 in aqua regia and reducing it with a reducing agent. In addition, other valuable metals other than gold can be recovered by a usual method, if necessary.

In addition, the waste alkali 105 was also quantitatively analyzed. The results are shown in Table 5 below. In the following Table 5, T-CN represents the total amount of CN of the complex cyanide compound and the free cyanide compound in the spent alkali (105).

[Example 2]

Except for the sintering condition, the same procedure as in Example 1 was carried out before washing. The firing was carried out under a reduced pressure of 400 占 폚, the rate of temperature rise was 3 占 폚 / min, and the firing time was 120 minutes after reaching 400 占 폚. The obtained fired residue 102 was subjected to quantitative analysis. The results are shown in Table 3.

[Example 3]

Except for the sintering condition, the same procedure as in Example 1 was carried out before washing. The firing was carried out under a reduced pressure of 650 占 폚, the rate of temperature rise was 3 占 폚 / min, and the firing time was 60 minutes after reaching 650 占 폚. The obtained fired residue 102 was subjected to quantitative analysis. The results are shown in Table 3.

[Comparative Example]

The concentrate 101 of the gold plating waste solution used in Example 1 was introduced into a sintering furnace and fired at 800 ° C. The firing was carried out under reduced pressure, and the rate of temperature rise was 3 ° C / min., And the firing time was 30 minutes after reaching 800 ° C.

As a result, it was confirmed that the alkali metal carbonate was melted and adhered to the wall surface of the furnace in the form of a glass, thereby corroding the furnace.

Although the gold recovery method has been described in the above embodiments, it is needless to say that other valuable metals such as noble metals and rare earth elements can also be recovered.

Although the present invention has been described in detail using specific forms, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. The present application is based on Japanese Patent Application (Japanese Patent Application No. 2013-091266) filed on April 24, 2013, which is incorporated by reference in its entirety.

Claims (4)

A step of firing a concentrate of a waste solution containing a cyanide compound, an inorganic carbonate and a valuable metal at a temperature of 400 to 650 DEG C, separating cyanide from the concentrate of the waste solution as a cyanide gas, and recovering the valuable metal from the calcined residue , A method for recovering valuable metals. The method according to claim 1,
And recovering the liquid metal from the liquid metal. 3. The method according to claim 1 or 2,
Wherein the inorganic carbonate is an alkali metal carbonate salt and / or an alkaline earth metal carbonate salt. 4. The method according to any one of claims 1 to 3,
Wherein the concentration of the cyanide compound and the carbonate concentration of the inorganic carbonate in the concentrate of the waste solution are 2 to 200 g / kg, 20 g / kg or more and less than 1000 g / kg, respectively.

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