JPH01111824A - Method for recovering gold from gold-containing liquid - Google Patents

Abstract

PURPOSE:To recover Au at a high yield by adjusting the pH of a liquid contg. Au and other heavy metals to a specific value, then passing the liquid through a chelate type ion exchange resin of a pyridine system to selectively adsorb the Au thereon, then eluting the Au by an alkaline liquid. CONSTITUTION:Industrial waste water or the like in which the Au and the heavy metals such as Fe, Ni, Cu, Zn, Sn, and Pb are dissolved and incorporated is adjusted to <=9 pH. This liquid is then passed in a column in which the chelate type ion exchange resin of the pyridine system is packed to adsorb the Au in the liquid selectively on the ion exchange resin. The other heavy metals are passed through the column without being adsorbed on the ion exchange resin. After this ion exchange resin is rinsed, an aq. soln. of an alkali metal cyanide such as NaCN or KCN or aq. soln. such as thiocyanate or thiosulfate is passed through the resin to elute the Au adsorbed thereon. The Au is thus recovered at the high yield.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention utilizes adsorption of gold present as ions in a solution onto an ion exchange resin and elution of the adsorbed gold with an alkaline solution to efficiently recover the gold. Concerning how to.

(Prior art and its problems) As a method for recovering gold from a gold-containing liquid, hydrazine, sodium borohydride, oxalic acid, metal powder (A
Common methods include a method in which a reducing agent (such as Z powder, Zn powder, Mg powder, Cu powder, etc.) is added and recovered, and an electrodeposition method. However, with these methods, several ppm of gold remains in the solution without being recovered, and when the total concentration of the gold-containing liquid is dilute, a large proportion of gold remains in the solution without being recovered. , there is a problem that the recovery rate decreases.

In addition to gold, gold-containing liquids intended for recovery often contain large amounts of heavy metals such as iron, nickel, copper, zinc, lead, and tin, and these are removed during gold dioxidation. There are problems in that heavy metals are mixed into the gold, making it difficult to obtain high-quality gold, and subsequent refining of the gold is time-consuming.

To solve the former problem, a method is known in which gold is concentrated and recovered using an ion exchange resin, but when recovering gold from a resin that has adsorbed gold, H (eluting gold from fat) is used. If gold cannot be recovered, the expensive resin must first be ashed to recover the gold, or even if it can be eluted, the elution rate is low and the recovery rate decreases, or the resin cannot be reused. There are some problems.

Furthermore, when a gold-containing liquid containing many impurities as mentioned above is used, gold and these heavy metals are adsorbed at the same time, which not only reduces the amount of gold adsorbed per ion exchange resin and increases recovery costs, but also increases the recovery cost. There are also problems such as heavy metals being mixed into the gold, reducing the quality of the gold obtained.

(Objective of the Invention) The present invention has been made in view of these problems, and it is an object of the present invention to provide a method for recovering high-grade gold that has a high recovery rate, allows reuse of ion exchange resin, and It is something.

(Means for solving the problems) As described above, the method for recovering gold from a gold-containing liquid according to the present invention includes:
The method is characterized by preparing a gold-containing solution to pH 9 or less, passing it through a pyridine-based chelating ion exchange resin to adsorb gold, and then recovering the gold by eluting the adsorbed gold with an alkaline eluent. That is.

(Function) The function of the present invention will be described below. The liquid containing gold is p
It is desirable to adjust it to 119 or less.

This is because if the pH is higher than 9, the amount of gold adsorbed to the ion exchange resin may decrease or may not be adsorbed at all.

Gold-containing liquids include those extracted from gold-containing scrap, gold-containing waste liquids discharged from gold-using processes, and trace amounts of gold discharged from gold recovery and refining processes. There are many things such as waste liquid.

A gold-containing liquid containing a large amount of heavy metals such as iron, nickel, copper, lead, zinc, and tin as impurities is suitable for the present invention.
There is no problem in applying the present invention to liquids that do not contain many impurities.

Also, the gold concentration in the gold-containing liquid is 50g/j! Although the following range is preferable, the present invention can be applied even if it is higher than this, and it can be said to be a preferable method especially when the amount of heavy metals is large (it is difficult to apply the conventional wet method).

It is also particularly effective for recovering several ppm of gold that cannot be precipitated by chemical reduction methods. This is because the solution after reduction in the chemical reduction method contains a large amount of heavy metals as impurities in addition to several ppm of gold.

When a gold-containing liquid is passed through a pyridine-based chelating ion exchange resin, gold is selectively adsorbed, and most of the heavy metals mentioned above are not adsorbed and flow out. This process separates gold and impurities, and high-quality gold can be obtained in the process described later.

Although there are many types of pyridine-based chelating ion exchange resins, Sumikylate CR-2 (trade name) was used in the examples.

Further, the adsorption operation is preferably carried out in a column manner, but may also be carried out in a batch manner.

The gold adsorbed on the resin is eluted with an alkaline eluent, but the case where the gold adsorbed on the resin is a chlorocomplex (chloroauric acid) will be described below.

When a gold-containing liquid is added to a resin, the gold (chloroauric acid) in the liquid binds to and is adsorbed to the sensitive groups of the resin at a certain distribution ratio.

When alkali cyanide is used as an alkaline eluent, the gold ligands adsorbed on the resin are removed from (C6-).
is substituted with cyanide (CN-) to form a stable gold-cyanide complex, and the distribution ratio between the resin and gold changes, and the properties of the resin itself also change depending on the pH, so the gold adsorbed on the resin is eluted as a gold cyano complex.

Since the gold cyano complex is the most stable gold complex in alkaline conditions, it can be said that the eluent containing alkali cyanide is excellent among the eluents of the present invention.

The alkaline eluent should contain alkali cyanide (sodium cyanide, potassium cyanide, etc.) as well as a compound capable of supplying a ligand such as thiocyanate or thiosulfate. If it contains one or more of these, it is possible to elute gold.

? 8 The syneresis was made alkaline because an alkaline eluent can elute gold from the resin more easily than an acidic eluent, and in addition to the above-mentioned compound for supplying the ligand. You may also add alkali hydroxide (sodium hydroxide, potassium hydroxide, etc.) or aqueous ammonia to the solution.

Furthermore, the resin after gold has been eluted can be used again after undergoing processes such as water washing and regeneration, which is advantageous.

When using resin in a column, adsorption (liquid passage),
In operations such as elution and regeneration, 5V is preferably 0.5 to 10, and in operations such as washing with water, 5V is preferably 5 to 30.

The obtained gold concentrate contains almost no heavy metals, so when gold is obtained from it, metallic gold with few impurities is obtained, and its quality is approximately 80% or higher. As methods for obtaining gold, the method using the aforementioned reducing agent and the electrodeposition method are common, but there are many other methods. Gold may be obtained by repeating the process multiple times or by performing separation operations such as membrane separation, solvent extraction, and ROJ (ROJ) UP to further remove impurities.

(Example 1) As shown in the drawing (gold-containing liquid obtained by dissolving Au-containing scrap in aqua regia (Au: 0.23 g/l, Fe:
0.55g/j! ,,Ni: L5g/11P
b: 0.023 g/l, Cu: 0.9 g/j! , p
H=0.8) 200 liters of pyridine-based chelating ion exchange resin (Sumichelate CR-
2) 0.5 liter of solution was passed through at 5V=2. 50th liter, 100th liter, 150th liter, 200th liter
When we analyzed the liquid that passed through the liter, gold was adsorbed as shown in the table, and heavy metals other than gold passed through without being adsorbed.

Table Resin passing liquid analysis results ND: Undetectable The resin after fitting was washed with 5 liters of pure water at 5 V = 20, and then with 2.5 liters of 5% KCN water at 5 V = 2.
Elute with 2.5 liters of washing water and wash with 5V=5, then add 2.5 liters of eluent containing gold and 2 liters of washing water containing gold.
．． I got 5 liters. When both liquids containing gold were mixed and analyzed to make 5 liters, Au: 9.28g/11
Fe: 3mg/II, Ni: 6mg/l, Cu:
6 mg/l, Pb: 2 rvr/l.

This solution was adjusted to pH=8 with dilute sulfuric acid, 100% of hydrazine hydrate (80%) was added to reduce the gold, filtered, washed, and dried.The dry weight was 45.98 g and the grade was 99. 9
5% metallic gold was obtained. The yield from charging the gold-containing liquid to recovering metallic gold was as high as 99.9% based on the pure amount of gold.

(Conventional Example 1) Gold-containing liquid obtained by dissolving Au-containing scrap in aqua regia (A u: 0.23 g/1, F'e:
0.55g/1, Ni: 1.5g/l, P
b: 0.023 g//l.

Cu: 0.9g/l, pH=0.8) Add 10g of hydrazine dihydrochloride to 1 liter to reduce gold, filter, wash, and dry. Dry weight is 0.22g and grade is 96.5.
% metallic gold was obtained. The yield from injecting the gold-containing liquid to recovering metallic gold was 92.3% based on the gold purity, which was lower than in Example 1, and the quality was also extremely low at 96.5%.

(Example 2) As shown in the drawing <Au: 5.8 g/l, Fe: 1
．． 7g/l, Cu: 1.2g/it, Zn: 0
．． Hydrochloric acid acidic gold-containing liquid containing 55g/j2 (pH=3)
was passed through 0.5 liter of pyridine-based chelating ion exchange resin packed in a column at 5v=i. Gold was adsorbed, and heavy metals other than gold passed through without being adsorbed.

After passing 8.3 liters of liquid, the gold concentration of the passing liquid was 2.
Since it became 2/l, the flow of liquid was stopped and the tube was washed with 5 liters of pure water at 5V=10. When the amount of gold adsorbed to the resin was calculated, it was found to be extremely high at 96.3 g per 1 liter of resin.

The resin after washing with water is KCN50g per liter, Kol
(Elute with 1.5 ZSV = 1 of eluent containing 10 g, and wash with 1.5 liters of washing water and 5 V = 5 to obtain 1.5 liters of eluent containing gold and 1.5 liters of washing water containing gold. Both gold-containing solutions were mixed to make a gold concentrate.

The resin after gold elution was then dissolved in 1 liter of 5% H2SO4.
Regenerate by passing the liquid at V=2, wash 2.5 liters of pure water at 5V=5, and remove the above liquid until the gold concentration of the passing liquid is 1.
The solution was passed until the concentration was in the range of ~10 mg/J.

According to the above method, the operation of uniform suit - water washing - gold elution -> water washing - resin regeneration - water washing = (coat suit) was repeated 9 times. During the process, the amount of gold-containing liquid passed through was determined to be 98.6 g on average per liter of resin.

In a total of 10 operations, 85 liters of gold-containing liquid was treated, and 30 liters of gold concentrate (Au: 16.40 g/j2) was obtained.

This concentrated solution was adjusted to pH=10 with dilute sulfuric acid, and then electrolyzed at a current density of 3 A/dm2 using a platinum-plated titanium plate as the anode and a stainless steel plate as the cathode to deposit gold.

After gold electrodeposition, gold with a grade of 99.5% is 494.5% from the cathode.
g was obtained. The yield from injecting the gold-containing liquid to recovering metallic gold was as high as 99.8% based on the amount of gold dose.

(Conventional example 2) Au: 5.8 g/l, Fe: 1.7 g/j2, Cu
: L2g/l, Zn : 0.55g/1 containing a hydrochloric acid acidic gold-containing solution (pH = 3) packed into a column using a weakly basic ion exchange resin (Diaion 5A20 (trade name), which is not a pyridine type). ) The solution was poured into 0.5 liter at SV=1. Heavy metals other than gold were adsorbed along with gold, and when 5.0 liters of liquid was passed through, the gold concentration of the passing liquid became 2 ■/L, so the passing of the liquid was stopped, and 5V = 1 with 5 liters of pure water.
Washed with water at 0. After calculating the amount of gold adsorbed to the resin,
The weight was 58.0 g per liter of resin, which was lower than in Example 2.

After washing the resin, SV with 1.5 liters of 5% KCN water.
= 1, and then 1.5 liters of washing water 5V = 5
When the two solutions were mixed, 3.0 liters of a solution was obtained in which part of the gold and most of the heavy metals other than gold were eluted. Analysis of this liquid revealed that A u: 4.27g
/ 1, Fe: 2.7g/l, Cu: 2.1g
/l, Zn: 0.50g/l, and the adsorbed gold (5
,8 g/l x 5.01 = 29.0 g) versus gold (4,27 g/l x 3.01
= 12.81 g), and only about half could be eluted.

The gold-containing eluent (3 liters) was diluted with dilute sulfuric acid to p + -
After preparing 1-8, sodium borohydride was added to 20
g was added to reduce gold and precipitate metallic gold.

Since the resin could not be reused, the gold was recovered after being incinerated and turned into ashes. 12.6 g of gold was recovered from the eluate and 16.0 g of gold was recovered from the ashed resin, but the former was of low quality as it was contaminated with heavy metals and the latter was contaminated with carbon. . The yield from injecting the gold-containing liquid to recovering metallic gold was 98.6% based on the gold dose, which was lower than in other examples.

(Example 3) As shown in the drawing <Au: 5.8g//! , Fe:1
, 7g/l, cu: 1.2g/l, Z n : 0.55
A hydrochloric acid acidic gold-containing solution (pH=3) containing g/It,
The solution was passed through 0.5 liter of pyridine-based chelating ion exchange resin packed in a column at 5V=1. gold is adsorbed,
Heavy metals other than gold passed through without being adsorbed. Since the gold concentration of the passed liquid became 2/1, the passing of the liquid was stopped and the sample was washed with 5 liters of pure water at 5V=10. After washing with water, the resin was eluted with 1.5 liters of eluent containing 50 g of KSCN and 10 g of SKOH per liter at a rate of 5V=1.
It was further washed with 1.5 liters of washing water (5V=5) to obtain 1.5 liters of a solution containing gold and 1.5 liters of washing water containing gold. Both gold-containing liquids were mixed to form a gold concentrate.

The resin after gold elution was then dissolved in 5% H2SO, 1 liter 5
Regenerate by passing the liquid at V=2, wash 2.5 liters of pure water at 5V=5, and pass the above liquid until the gold concentration of the passing liquid is 1~1.
The solution was passed until the ratio was within the range of 10 μ/1.

In the above method, the operations of gold adsorption, water washing, gold elution, water washing, resin regeneration, water washing, and (total adsorption) were repeated nine times.

A gold concentrate was obtained through a total of 10 operations. This concentrated solution was adjusted to pH=12 with dilute sulfuric acid, and then heated at 3 A/2 using a platinized titanium plate as the anode and a stainless steel plate as the cathode.
Gold was deposited by electrolysis at a current density of d m''.

High-grade gold could be obtained from the cathode, and the resin could be used multiple times.

(Example 4) As shown in the drawing, scrap containing Au was dissolved in aqua regia and then reduced with hydrazine.
0.006g/j2, Fe: 1.7g/l, N
i: 0.8g/12, Pb: 0.42g/j
! , Cu: 3.5g/l, 3n: 0.85g/
1,000 liters of pyridine-based chelating ion exchange resin (pH=1.5) was packed into a column.
The solution was passed through 0.1 liter of Sumikylate CR-2) at 5V=2. 250 liters, 500 liters, 750
When the 1 J liter and 1000 liter passing liquid was analyzed, gold was adsorbed as shown in the table, and heavy metals other than gold passed through without being adsorbed.

Table Analytical results of resin passing liquid Resin after coating was 5V = 20 with 2.0 liters of pure water.
After washing with water, turn the voltage to 5V with 0.5 liters of 5% KCN water.
= 2, and further washed with 0.5 liters of washing water and 5V=5 to obtain 0.5 liters of eluent containing gold and 0.5 liters of washing water containing gold. When both liquids containing gold were mixed to make 1 liter and analyzed, Au: 5.91 g/
l, Fe: 5mg/l, Ni: 4ttvg/1.
, Cu: 8mg/l, Pb: 1trg/l.

Sn: 1■/l, concentrated 1000 times.

After adjusting this liquid to pH=10 with dilute sulfuric acid, 10 g of sodium borohydride was added to reduce the gold, filtered, washed, and dried. The dry weight was 5.90 g and the grade was 99.7%.
of metallic gold was obtained, and the yield from the time the gold-containing liquid was introduced to the time when the metallic gold was recovered was 98.0% of the total amount of pure gold. Both yields were very high.

(Effects of the Invention) The present invention provides the following advantages when recovering gold from a gold-containing liquid:
Gold is selectively adsorbed on a pyridine-based chelating ion exchange resin, and gold is eluted with an alkaline eluent.
The ion exchange resin is reused, while high-grade gold can be recovered.

In the present invention, there are fewer impurities mixed in the gold recovered as in the past, and high-quality gold can be obtained, and the resin adsorbed with gold can be easily eluted, and it can be used many times. In addition, it has other effects such as greatly improving yields and reducing recovery and refining costs, making it a great contribution to industry in recovering rare metals like gold.

[Brief explanation of the drawing]

The accompanying drawing is a block flow diagram of a complete recovery process illustrating the implementation of the present invention. Applicant Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (2)

[Claims] (1) Prepare the gold-containing solution to pH 9 or less, pass it through a pyridine-based chelating ion exchange resin to adsorb the gold, and recover the gold by eluting the adsorbed gold with an alkaline eluent. A method for recovering gold from a gold-containing liquid. (2) The method according to claim 1, wherein the alkaline eluent contains at least one of alkali cyanide, thiocyanate, and thiosulfate.