JP2706276B2 - How to remove silver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for removing silver from a solution containing silver ions, and more particularly, to recovery and refining of non-ferrous metals and precious metals, manufacturing processes of compounds, and the like. A method for selectively removing silver.

(Prior art and its problems) Conventionally, as a method for selectively removing silver from a solution containing silver, a method of adding a chloride to form a sparingly soluble silver salt or a method of substituting with a metal lower than silver is used. There is known a method of adsorbing on an adsorbent such as a chelate resin.

As an example of the silver removal treatment, the problems of the prior art in the copper refining process will be described.

In blister copper (anode) used for electrolytic refining of copper,
It contains hundreds to thousands of ppm of silver. Most of the silver is separated as anode slime by electrolytic refining, but a part of the silver is eluted into the electrolyte. Silver ions are deposited together with copper ions on the cathode, so several tens of pp
m of silver will be mixed. Also, when trying to obtain high-purity copper by lowering the silver concentration and increasing the silver concentration, this tendency becomes more remarkable, and ordinary copper (silver content about 10 ppm) is charged. Even so, several ppm of silver will be contained in the refined electrolytic copper.

Desilvering is performed to prevent these problems.However, it is difficult to reduce the silver concentration in the electrolytic solution to 0.1 ppm or less by the method of adding a chloride to the electrolytic solution to generate a hardly soluble silver salt. Since the copper concentration in the medium is about 50 to 100 g / l, it is difficult to reduce the amount of silver in the obtained electrolytic copper to 1 ppm or less.

In the method of substituting with a metal lower than silver, for example, there is a method of adding copper powder to an electrolytic solution to replace silver and copper, but it is still difficult to reduce the silver concentration in the electrolytic solution to 0.1 ppm or less,
It is difficult to reduce the amount of silver in the obtained electrolytic copper to 1 ppm or less.

It can be said that the above two methods are more suitable for a process in which an input material having a high silver concentration is used and silver may be slightly mixed in the obtained product.

On the other hand, the method of adsorbing silver on an adsorbent such as a chelate resin can reduce the silver concentration in the electrolytic solution to 0.1 ppm or less, so that a product having a low silver content can be obtained.
However, there are restrictions on the use of chelating resins, and when there is an oxidizing component in the electrolyte or when the electrolyte is strongly acidic, the resin is likely to deteriorate, shortening the life of the resin, and deteriorating the adsorption characteristics.
There are many cases where the range of use greatly depends on the pH and is limited. In addition, the adsorption capacity of resin is theoretically
Although it has the ability to adsorb several tens of g of silver per unit, it absorbs several g per unit in order to reduce the silver concentration in the electrolyte to 0.1 ppm or less as described above due to interference from other elements such as nickel. In some cases, the effect may be lost.

Further, when the silver concentration contained in the electrolyte is high, the destruction of the resin occurs quickly, so that application to a material having a high silver concentration is not suitable.

Furthermore, in order to regenerate and use the chelate resin on which silver is adsorbed, silver can be recovered using an alkali cyanide, EDTA, thiosulfate, or the like as a complexing agent, and the resin can be regenerated. With respect to the amount of silver adsorbed, complexing agents used for elution of silver are expensive, toxic,
There are problems such as deterioration of the resin due to alkali, and the running cost for regeneration is high. Therefore, it is not suitable for the purpose of recovering silver as a by-product.

As described above, the chelate resin method is suitable for a process in which a high-purity product is obtained by using an input material having a low silver concentration, but the reverse case is not suitable.

As mentioned above, the problem of the silver removal method has been described using copper electrolytic refining as an example.In addition, other processes involving silver, such as wet refining of noble metals such as gold and palladium, electrolytic refining, and gold and palladium containing silver There are many things such as recovery of precious metals and copper from waste materials of copper and copper, desilvering from plating solutions and waste solutions from the photographic industry, and production of copper and precious metal compounds.

Under these circumstances, a more desirable method of removing silver has been desired.

(Object of the Invention) The present invention has been made in order to solve the above problems, and is a method for selectively removing silver from a solution containing silver ions. It is an object of the present invention to provide a versatile desilvering method that can economically and easily perform desilvering in a process such as a compound manufacturing process.

(Means for Solving the Problems) The present invention provides a method for removing silver from a solution containing silver ions, wherein silver ions in the solution are selectively removed by an adsorbent containing tetratitanate as an ion exchanger. By doing so, it is possible to reduce the silver in the solution to a level of several ppb to several ppm, which is superior to conventional methods in terms of economy, simplicity, application range, versatility, etc. I found it.

(Operation) Hereinafter, in order to clarify the present invention, the operation of the present invention will be described.

The solution containing silver ions can be used mainly for the liquid used or generated in the recovery or refining process of the non-ferrous metal or the noble metal as described above.
Sulfuric acid electrolytic solution and washing solution in the copper refining process, hydrochloric acid acid solution containing a large amount of gold in gold refining, nitric acid solution or hydrochloric acid solution containing palladium generated during palladium refining, including noble metals and copper There are a solution in which scraps are dissolved with an acid or the like, a solution containing various metal ions, and the like, as well as a plating solution and a photographic waste solution.

Silver ion types include those derived from silver nitrate or silver sulfate, silver ammine complexes, thiosulfate complexes, chelate complexes that have a weak bond with silver, etc., but those that have too strong a cyano complex or complex coordination. Is less preferred.

Therefore, in addition to acidic liquids such as sulfuric acid, nitric acid and hydrochloric acid,
Since the present invention may contain a silver complexing agent such as ammonium ion, thiosulfate ion, and chelate, and may have a neutral or alkaline liquidity in acidity, the present invention provides a variety of methods compared to conventional methods. There is a feature that can correspond to the liquid properties of

When this solution is brought into contact with an ion exchanger containing tetratitanate, silver tetratitanate is formed by an ion exchange reaction, and silver in the solution can be removed.

The tetratitanate may be exchanged with hydrogen ions with a strong acid prior to ion exchange with silver to form hydrated tetratitanic acid and then used in the reaction with silver.

The reaction between tetratitanate and silver ion is represented by formula (1), and the reaction for forming hydrated tetratitanate from tetratitanate is represented by formula (2). The reaction is shown in equation (3).

X ₂ O · 4TiO ₂ + 2Ag ⁺ → Ag ₂ O · 4TiO ₂ + 2X ⁺ (1) X ₂ O · 4TiO ₂ + 2H ⁺ → H ₂ O · 4TiO ₂ + 2H ⁺ (2) H ₂ O · 4TiO ₂ + 2Ag ⁺ → Ag ₂ O · 4TiO ₂ + 2H ⁺ (3) where X is a monovalent ion typified by an alkali metal, and when treating an acidic silver-containing liquid such as lithium, potassium, sodium, and ammonium, tetratitanate is used. The former method or the latter method may be used since the ion exchange between the salt and silver ion occurs quickly.

The latter method is superior in treating a neutral or alkaline silver-containing liquid, and when the pH of the silver-containing liquid is generally 5 or less, the former method or the latter method may be used.
The latter method is better for pH 5 or higher.

Tetratitanate has very good selectivity for silver ions over a wide range of hydrogen ion concentrations, from alkali to strongly acidic, with little adsorption of other heavy metals. Therefore, in the present invention, it is not necessary to control the pH unlike the conventional chelate resin method. However, alkali metal ions exhibit adsorption characteristics near neutrality. Therefore, when the alkali metal ion is excessive, the pH is preferably 5 or lower, but may be 5 or higher if the alkali metal ion is small.

In the present invention, the adsorbed silver can be eluted with a complexing agent such as cyanide, and also with a strong acid. In order to elute silver with an acid, sulfuric acid or nitric acid of 6 N or more is preferable, and nitric acid is more preferable because it can be eluted with a lower acid normality than sulfuric acid and the solubility of silver ions can be increased. The use of hydrochloric acid is not preferred because silver chloride is formed.

In addition, titanates and / or hydrated tetratitanic acids have a feature that they have a large silver adsorption capacity. Conventional chelates could adsorb only tens of g of silver per resin, but silver titanate. Salt or hydrated tetratitanic acid can adsorb about 400 g of silver per kg. Therefore, the labor involved in the adsorption and desorption of silver is reduced compared to the conventional chelate resin method.
It can be reduced to 1/10 and an eluate enriched in silver can be obtained.

Hereinafter, examples according to the present invention will be described, but the present invention is not limited to these examples.

(Example 1) In this example, the present invention was applied to electrolytic refining of copper, and was performed using the apparatus shown in the figure.

500 ml of hydrated tetratitanic acid (H ₂ O · 4TiO ₂ ) in which potassium of potassium tetratitanate (K ₂ O · 4TiO ₂ ) was replaced by hydrogen was charged into the adsorption tower 6, and the electrolytic solution 5 contained (copper 45 g / l, free sulfuric acid 130g /
l, hydrochloric acid 0.5g / l, nickel 0.3g / l, glue 0.2g / l) 50l
(25 liters for both anode and cathode) and a blister copper plate (size: 250wX550hX10t, silver 99.5%, gold 0.02%, silver 0.21)
%, Nickel 0.05% or less) and two high-purity copper plates (size: 250wX550hX1t, copper 99.995% or more, gold 0.1ppm or less, silver 0.1ppm or less, nickel 0.1ppm or less) are hung on the cathode 2. I dropped it.

For the diaphragm 3, a 2 mm thick glass porous plate (glass filter) sandwiched between two 5t vinyl chloride reinforcing plates with many 10mm holes is used. 3 was set in the center.

The liquid on the anode side is circulated into the anode bag 4 by the pump 7, and a part of the liquid is transferred to the cathode side through the adsorption tower 6 at 2 l / hr.
The electrolytic refining of copper was performed over 12 days (288 hours) by supplying electricity at 60 ° C. and 55 A (2 A / dm ² ).

Table 1 shows the values obtained by analyzing silver in the electrolyte solution 5 on the cathode side and the anode side every 48 hours during electrolysis.

Analysis of the copper deposited on the anode revealed that the quality was 99.995% or more copper, 0.1 ppm or less gold, 0.3 ppm of silver, and 0.1 ppm of nickel.

In the present example, silver was desilvered when the electrolytic solution was sent from the anode side to the cathode side, so that high-grade copper could be obtained from low-grade crude copper.

(Conventional Example 1) In this conventional example, the chelating resin is filled in the adsorption tower 6 using the apparatus shown in the figure for the purpose of comparison with Example 1.

500ml thiol chelate resin (MA, Hokuetsu Carbon)
Is packed in an adsorption tower 6, and the electrolyte 5 contains (copper 45g / l, free sulfuric acid 130g / l, hydrochloric acid 0.5g / l, nickel 0.3g / l, glue 0.2g / l).
l) is used in 50 l (both anode and cathode are 25 l each), and the anode 1 is a blister copper plate (size: 250wX550hX10t, silver 99.5%, gold 0.02
%, Silver 0.21%, nickel 0.05% or less), and a high purity copper plate (size: 250wX550hX1t, silver 99.
995% or more, gold 0.1ppm or less, silver 0.1ppm or less, nickel 0.1
(ppm or less) Two were suspended.

For the diaphragm 3, a 2 mm thick glass porous plate (glass filter) sandwiched between two 5t vinyl chloride reinforcing plates with many 10mm holes is used. 3 was set in the center.

The liquid on the anode side is circulated into the anode bag 4 by the pump 7, and part of the liquid is discharged to the cathode side through the adsorption tower at a rate of 2 l / hr, and energized at 60 ° C. and 5 A (2 A / dm ² ). Then 12
Copper electrorefining was performed over a period of days (288 hours).

Table 2 shows the values obtained by analyzing silver in the electrolyte solution 5 on the cathode side and the anode side every 48 hours during electrolysis.

When the copper deposited on the anode was analyzed, it was found to be 99.995% or more copper, 0.1ppm or less gold, 27ppm silver, and 0.1ppm nickel. Was started to occur, and the silver concentration in the copper obtained was higher than that in Example 1 because the silver concentration on the cathode side increased.

Example 2 In this example, the present invention was applied to the production of high-purity gold by electrolytic refining of gold, and was performed using the apparatus shown in the figure.

500 ml of hydrated tetratitanic acid (H ₂ O · 4TiO ₂ ) in which potassium of potassium tetratitanate (K ₂ O · 4TiO ₂ ) was replaced with hydrogen was charged into the adsorption tower 6, and the electrolytic solution 5 contained (88 g / gold) l, free hydrochloric acid 100g /
l) was used in 50 liters (25 liters for both the anode and the cathode), and a coarse metal plate (size: 250wX300hX10t, gold 99.98%, silver 0.014) was used for the anode 1.
%) 1 sheet is suspended and a high purity gold plate (size: 100wX150hX1t, gold 99.999% or more, silver 0.5ppm or less) is placed on the cathode 2.
The pieces were hung.

For the diaphragm 3, a 2 mm thick glass porous plate (glass filter) sandwiched between two 5t vinyl chloride reinforcing plates with many 10mm holes is used. Was set in the center.

The liquid on the anode side is circulated into the anode bag 4 by the pump 7, and a part of the liquid flows through the adsorption tower 6 to the cathode side at 0.7 l / h.
Flow out each r, DC current 18A at 80 ° C (3A / dm ² )
An AC current of 35 A (6 A / dm ² ) was applied to the mixture to perform AC superposition electrolysis.

Two days after the start of electrolysis, the gold deposited on the cathode was taken out and analyzed. As a result, it was found that the purity was 99.999% or more and 0.5 ppm or less of silver.

(Conventional Example 2) In this conventional example, the apparatus shown in the figure is used in comparison with Example 2, and no desorbing substance is put into the adsorption tower 6 and a large excess of chloride ions causes desilvering by silver chloride formation. This is an example of performing. In gold electrolysis, since chloride ions are contained as hydrochloric acid, silver chloride is usually formed during electrolysis to remove silver.

For the electrolyte 5, 50 liters (95 g / l of gold, 95 g / l of free hydrochloric acid) were used (25 liters for both the anode and the cathode), and the anode 1 was a coarse gold plate (size: 200 wX300 hX10 t, 99.98% gold, 0.014% silver). , And a high-purity gold plate (size: 100wX150hX1
t, gold 99.999% or more, silver 0.5 ppm or less).

For the diaphragm 3, a 2 mm thick glass porous plate (glass filter) sandwiched between two 5t vinyl chloride reinforcing plates with many 10mm holes is used. Was set in the center.

The liquid on the anode side is circulated into the anode bag 4 by the pump 7, and a part of the liquid flows to the cathode side through the adsorption tower at 0.7 l / hr.
Flow at 80 ° C, DC current 18A (3A / dm ² )
An AC current of 35 A (6 A / dm ² ) was applied to the mixture to perform AC superposition electrolysis.

Two days after the start of the electrolysis, the gold deposited on the cathode was taken out and analyzed. As a result, it was found to be 99.997% or more in gold and 12ppm in silver.
It couldn't be higher than 9.999.

(Example 3) In this example, the present invention is applied to the separation and recovery of palladium and silver from an ammoniacal waste liquid (pH = 9) containing silver and palladium.

Ammonia waste liquid containing silver and palladium (pH = 9,
Silver: 2.1 g / l, palladium: 3.5 g / l), hydrated tetratitanic acid 10
SV into a cylindrical column with a diameter of 50 mm and a length of 35 cm filled with 00 ml
= 100 l and then 2.5 l of pure water to wash the resin.

The concentration of silver in the passing solution was 1 mg / l or less, and the concentration of palladium was 35 g / l. Silver was adsorbed and palladium was not adsorbed.

Silver was eluted by passing 5 l of 6N nitric acid through the column after silver adsorption, and then washed with 2.5 l of pure water.As a result, 209.6 g, 99.8% of the adsorbed silver, could be eluted and recovered. .

Example 4 In this example, the present invention was applied to the separation and recovery of palladium and silver from an ammoniacal waste liquid (pH = 9) containing silver and palladium, and tetratitanium was used instead of hydrated tetratitanic acid. It uses potassium acid.

Ammonia waste liquid containing silver and palladium (pH = 9,
(Silver: 2.1 g / l, palladium: 3.5 g / l) and sulfuric acid were added to adjust the pH to 1
And 100 l of liquid were passed through a cylindrical column having a diameter of 50 mm and a length of 35 cm filled with 1000 ml of potassium tetratitanate at a speed of SV = 1.
Further, 2.5 l of pure water was passed through to wash the resin.

Silver was adsorbed at a silver concentration of 1 mg / l or less in the flow-through liquid, and palladium was obtained without adsorption of 352.4 g corresponding to 100.7%.

Silver was eluted by passing 5 l of 6N nitric acid through the column after silver adsorption, and further washed with 2.5 l of pure water.As a result, 215.3 g, 102.5% of the adsorbed silver, could be eluted and recovered. .

(Conventional example 3) In this conventional example, the chloride ion addition method of the conventional example is applied to the separation and recovery of palladium and silver from an ammoniacal waste liquid (pH = 9) containing silver and palladium.

Ammonia waste liquid containing silver and palladium (pH = 9,
1.0 kg of sodium chloride was added to 100 l of silver (2.1 g / l, palladium: 3.5 g / l) and stirred well.

However, no silver chloride precipitate could be obtained, and silver could not be separated and recovered.

(Conventional Example 4) In this conventional example, a chelate resin method is applied to the separation and recovery of palladium and silver from an ammoniacal waste liquid (pH = 9) containing silver and palladium.

Ammonia waste liquid containing silver and palladium (pH = 9,
(Silver: 2.1 g / l, palladium: 3.5 g / l) with sulfuric acid to adjust the pH to 2.
5, 50m diameter filled with 100ml of chelating resin (Hokuetsu MA)
10 liters of liquid were passed through a cylindrical column having a length of 35 cm and a length of 35 cm at a speed of SV = 1, and then 2.5 liters of pure water was passed through the column to wash the resin. However, under the influence of ammonia, the passing solution contained about 100 ppm of silver, and only 95.7% of palladium was contained in the passing solution, so the remaining 4.3%, 0.8 g, was absorbed by the resin.

(Example 5) In this example, the present invention is applied to the recovery of silver from a waste liquid from a silver nitrate production process.

Wastewater from the silver nitrate production process containing a large amount of silver (pH = 0.3, silver:
87g / l), and put SV into a column filled with 25l of potassium tetratitanate.
After 100 l of liquid were passed through at a rate of = 1, dehydration was carried out well by vacuum.

Then, 40 l of 7.5 N nitric acid was passed through the column after silver adsorption to elute silver, and the solution was evacuated and vacuumed. The silver was dissolved and returned to the silver nitrate mother liquor where crystallization was repeated and used.

Conventionally, the waste liquid from such a process had to be once reduced with copper powder or the like to be silver and then reused, but according to the present invention, the contaminants in the waste liquid and silver were separated, and only silver was taken out. It can be reused.

(Example 6) In this example, the present invention is applied to the recovery of silver from photographic waste liquid, and the present invention is applied to a method for removing silver from a solution containing a large amount of thiosulfate.

Wastewater from the photography industry containing a large amount of thiosulfate (silver: 05g / l)
Was adjusted to pH 1 and 3000 l of liquid were passed through the column filled with 25 l of potassium tetratitanate at a speed of SV = 1 to adsorb silver.

Silver in the processing solution was 0.5 ppm or less, and silver could be recovered.

Then, 100 L of 9.0 N sulfuric acid was passed through the column after silver adsorption to elute silver, and silver could be recovered.

Conventionally, there has been no good recovery method when such a strong complexing agent is contained, but the present invention makes it possible to easily recover silver in a waste liquid.

(Effect of the Invention) As described above, in the method for removing silver according to the present invention, by using tetratitanate, it is possible to provide a versatile desilvering method that can be performed economically and easily.

There are many processes to which the present invention can be applied, such as refining non-ferrous metals and precious metals, manufacturing chemicals, and recovering valuable resources. However, it is important, and it can be said that the effect of the present invention is great.

[Brief description of the drawings]

The figure is a schematic drawing of an electrolysis apparatus using the present invention for electrolytic refining of copper and gold.

Claims (2)

(57) [Claims] 1. A method for removing silver from a solution containing silver ions, wherein silver ions in the solution are selectively removed by an adsorbent containing tetratitanate as an ion exchanger. Method. 2. The method for removing silver according to claim 1, wherein the tetratitanate is treated with an acid to obtain hydrated tetratitanic acid before silver ions are removed.