JPS60208435A - Recovering method of gold - Google Patents

Abstract

PURPOSE:To recover high-purity gold of >=99.998% without an electrolytic refining method by subjecting an aq. soln. contg. thickened gold to solvent extraction, dissolving the reduced crude gold formed by reducing said soln. at a high temp. and blowing the dissolved crude gold to a gaseous mixture composed of gaseous chlorine and inert gas. CONSTITUTION:The precipitate of copper electrolysis or the precipitate of decopperization obtd. by decopperizing and arsenizing said precipitate is made into a slurry by using an aq. metallic chloride soln. of NaCl, MgCl2, etc. and is then subjected to gaseous chlorine leaching. Preferably an aq. NH3 soln. is added to the resultant decoction in which gold is leached at >=99.5% to precipitate and remove Pt, etc. in the form of insoluble salt. The decoction from which Pd and Pd are removed is subjected to solvent extraction of gold by using a solvent having good selectivity with gold (e.g.; dibutyl carbitol). The reduced crude gold obtd. by reducing the soln. of gold extraction by a reducing agent such as oxalic acid or the like is dissolved at 1,100-1,200 deg.C and a gaseous mixture composed of gaseous chlorine and inert gas is blown thereto to evaporate and remove impurities. The above-described gold having high purity is thus recovered.

Description

[Detailed description of the invention]

The present invention relates to a method for recovering 99.998% or more of gold from an aqueous solution containing gold by omitting an electrolytic refining step. Gold is recovered as a by-product of smelting copper, ships, zinc, etc., as well as by smelting whole ores, and various refining methods are used depending on the raw material. Generally, these methods involve a number of problems, as the gold bullion is recovered only after several long and complicated processing steps. To explain specifically using an electrolytic solution of copper as an example, in the process of electrolytically manufacturing copper, a copper electrolytic solution, also called anode mud, is deposited at the bottom of the electrolytic tank. This copper electrolyte contains gold, silver,
Because it contains valuable elements such as platinum group elements, selenium, and tellurium, recovering these elements at the right time, in high yield, and at low cost will not only help improve the profitability of the smelter, but will also
This is extremely desirable for our country, which is poor in resources. Gold is the most expensive of these valuable elements, and rationalization of the recovery method for gold is most strongly desired. According to the conventional example of recovery of dismantled steel materials in Japan,
The slime is first decoppered by sulfuric acid leaching or sulfated roasting, and then oxidized and roasted at 900 to 100 OK to volatilize and separate Se to 8e01. The main component of the roasted powder is PbSO4, which is then reductively smelted in a blast furnace with the addition of a solvent to collect Au and Ag in noble lead, which is then treated using the shebuki method in a silver separation furnace. Ag is recovered by the Mocbius electrolysis method after being made into rough g, and further Au is recovered from the anode slime. That is, the anode slime from As IK Wt is HN
After treatment with Oa and dissolving Ag and Pd, Au95-98%,
The anode is Kawahara metal plate containing 1 to 3% Ag, and the Woh 1w
19 yen purification by method 111. During electrolysis, direct current alone will passivate the anode and make it difficult to dissolve Au, so alternating current is used in combination with heavy weight 1 to advance the electrolysis. This requires extremely long process steps, and since the process involves smelting a material that is an aggregate of complex compounds, the direct extraction rate varies and repeated smelting is unavoidably necessary. So,
It was disadvantageous not only in terms of yield and cost but also in terms of interest rate because it required a long mortar for collection. Furthermore, the amount of gold required to maintain total electrolysis is high, and platinum, palladium, etc. dissolve in the electrolyte, so periodic purification is required, and AC/DC superposition is required for electrolysis. In addition, there are many drawbacks such as a large amount of anode sludge (gold powder, etc.) generated during electrolysis. Recently, gold in aqueous solution was extracted from organic phase by solvent extraction method [I
A method has also been proposed in which gold is reduced and back-extracted and reduced from it, but this method alone is by no means sufficient when applied to the treatment of materials containing a wide variety of impurities, such as metal electrolytes. It's not possible. Therefore, it is desired to establish a method to easily, reliably, and quickly recover gold from raw materials that coexist with various impurities in the form of high-purity gold of 99.998% or more, but conventional methods All of them have their merits and merits, and no method that is completely satisfactory has yet been found. Therefore, recently, the chlorine gas leaching method has been attracting attention as an alternative method. The basic gas leaching method is to make a slurry of copper-decompressed material or decopper-removed dispersion obtained by decoppering and dearsenizing it, and blowing chlorine gas into it. Silver is separated from the leaching residue fixed in the form of Ag01. The chlorine gas leaching method uses an aqueous slurry as the slurry into which chlorine gas is blown, a method in which the material is slurried in an aqueous hydrochloric acid solution, and a method in which chlorides of Group 1 and Group II metals of the periodic table (Na11, Mg
G! There is a method in which the transported material is made into a slurry using a slurry (e.g., It is superior to the previous two Nagisa in that it is able to elute 99.5% or more of Ag01 into the leachate and at the same time confine 99.5% or more of the silver in the transported material in the leaching residue as Ag01. In any case, the leachate in the chlorine gas leaching process is an important source of total recovery. In addition to gold, this leachate also contains some Ag, Pt, and P.
d, Pb, Se STe, Bi, sb, Fe
other mild impurities coexist

[There is. In order to efficiently recover gold from the leachate, a solvent extraction method is advantageously used in which gold is fused with a solvent that has excellent selectivity for gold, such as J) BO (dibutylcarpitol or diethylene glycol-D-butyl ether). It can be done. However, in addition to gold, Ag,
Since impurities such as Te, Fe, and Pb are inevitably extracted at the same time, some of these impurities are inevitably included in the reduced gold that is precipitated by adding a reducing agent to the extract. Therefore, it is desired to establish a simple and efficient method for separating impurities from reduced gold obtained by solvent extraction, and this is the objective of the present invention. However, most of the other recovery methods currently in use ultimately result in the step of obtaining reduced gold by solvent extraction, and in subsequent steps It is also necessary to remove impurities from gold.In order to obtain high purity reduced gold obtained from solvent extraction, it is necessary to cast raw metal plate anodes and use them. It was common knowledge in the industry that the only option was to electrolytically MH the gold.For example, a method was proposed in which reduced gold obtained by solvent extraction was oxidized and then melted with the addition of soda ash. Although this is a very useful method, K to obtain high-grade (ffl) gold ultimately requires electrolytic refining. Therefore, it would be extremely beneficial if gold with a purity of 99.998% or higher could be recovered by omitting the electrolytic refining process. We have repeatedly investigated a method for recovering 99.998% or more of highly concentrated gold from an aqueous solution containing gold, preferably a hydrochloric acid solution, without going through the electrolytic purification method. After solvent extraction, reduced crude gold is obtained using an appropriate organic reducing agent, melted at a high temperature of 1,100 to 1,200°C, and mixed gas of chlorine gas and inert gas is blown into it to form a mold as it is. It is 441E that TJJ is capable of recovering high-grade gold of over 99.998%.
llJshita. The production of coarse gold by injecting at gas has long been known as the Miller method; There has yet to be an attempt to volatilize and remove impurities by applying an inert gas to reduced gold obtained through solvent extraction and purification from a water bath solution, thereby obtaining high-purity gold without performing full electrolysis. Thus, the present invention provides reduced crude gold produced by solvent extraction and reduction of a concentrated aqueous solution of gold to 110
To provide a method for recovering high-purity gold from a trap by melting it at a high temperature of 0 to 1200°C and blowing a mixed gas of chlorine gas and inert gas. A typical example of a gold concentrated aqueous solution is a leaching solution obtained by leaching copper-removed material or decopper-removed dispersion obtained by decoppering and arsenization with chlorine gas to condense gold. The present invention will be described below. First, a method for leaching copper electrolyte with chlorine gas will be described as an example of a prerequisite step to the present invention. Copper electrolyte still contains a significant amount of copper, so
It is common that copper is removed and arsenization is removed. Various methods have already been established for copper removal treatment, and methods such as sulfuric acid leaching, sulfated roasting and acid leaching, or leaching with the addition of Fe''+Imene can be used.
70D [AuSAg5Pe, depending on source and processing method;
Pd5Ou1As, Se. Te, Pb, Bi, Fe, Sb, S, Si
ng etc. in various ranges. As mentioned above, the most important target to be considered in a system for recovering these valuable elements is total recovery. The electrolytic waste or copper-removed powder, preferably the copper-removed powder, is leached with chlorine gas in a slurry state in a chlorine gas leaching step. Copper't11. As mentioned above, water, hydrochloric acid solution, and aqueous chloride solutions of metals from Groups 1 to 2 of the periodic table have been proposed as media for slurrying precipitate or decoppered powder. When hydrochloric acid is used, the bathing rate of gold and the fixation rate of silver are poor, so Na11 and Mg0
1. It is convenient to use an aqueous chloride solution of metals from Groups 1 to 2 of the periodic table represented by the following to form a slurry of the powder. For example, when a hydrochloric acid slurry is used, a significant amount of chloride is redissolved, reducing the total concentration in the leachate and reducing the silver recovery as Ag01 residue to a maximum of 98%.
．． In contrast, when Na(!1 slurry is used, the leachate containing more than 99.5% of gold and 99%
．． A residue with 5% or more of silver fixed as AgCl is produced. In the above chlorine leaching method using metal chlorides, Na11 and MgC1 are typically used as metal chlorides, but in addition, KC1, OaO1, BaCl2, Be
11 is also preferably used. The metal chloride concentration is generally 1
-5N, preferably 2.5-3.5N. In an open or closed container, the slurry is
Blown with chlorine gas at a temperature of ~80°C. The slurry is stirred by stirring blades installed in the container, for example, 200~
Preferably, the mixture is stirred at a stirring speed of 11,000 rpm. The amount of chlorine gas blown is determined to be an appropriate amount to bring about the specified total elution, but it is possible to reduce the amount of silver to more than 99.5% by infusing the slurry at a rate of 200 to 1,500 cc/min/l for 5 to 7 hours. It is possible to immobilize and extract more than 99% of gold and other valuable metals. The preferred method of recording is to have the first half 15 to 3 times more effective than the second half. For example, 400-600 for the first 2-4 hours.
It is preferable to use half the slurry for 1 to 4 hours per minute per minute. Slurry concentration is 200-4009
/"l. If the slurry concentration is too low, the liquid field will drop and silver and lead will be easily eluted. The scattered slurry, which has been blown with chlorine gas for a specified period of time, becomes a leachate in which more than 995% of the gold has been eluted. and 99.5% silver
The residue retained as Ag01 is converted into the residue, and after solid-liquid separation, it is subjected to post-processing to recover the valuable elements contained in each. The chlorine leaching method is an advantageous method in that early in the process, the powdered gold can be obtained as a highly concentrated leachate and the silver can be obtained as a leaching residue concentrated in the form of Ag01. Another notable advantage is that the separation rate between gold and silver is good. More than 99.5% of the gold contained in the material is eluted in the leaching solution obtained in this way, but at the same time, Pt,
Platinum group elements such as Pd and silver are also eluted, and Pb, Se,
Te5Ei, 8b% Fo and other impurities are also present. After this, although optional, platinum group elements such as pt and pd are recovered prior to total recovery. Solvent extraction methods may also be used for this purpose, but a simpler and more efficient method is to add aqueous ammonia, generally at an acid concentration of 6 to 8N (Naoa
The method is to adjust the acid concentration of the leached waves having a concentration of 4 to 4.5 N (addition equivalent) to precipitate Pt, Pd, etc. as insoluble salts. The leachate is then processed by solvent extraction using a solvent with good selectivity for gold. As the solvent, DBO (dibutylcarpitol or diethylene glycol-n-butyl ether) is typically used, but methyl isobutyl ketone or a mixture thereof with isoamyl acetate may also be used. Solvent extraction is carried out by thoroughly mixing the leaching liquid and the solvent at room temperature at an A10 ratio of 1 to 2, and then standing to separate the organic phase and the aqueous phase. The gold present in it migrates to the organic phase. At that time, Ag, T
Impurities such as e, Fa, and Pb are also transferred. It has been found that during extraction, the rate at which impurities are extracted together with gold is largely dependent on the free hydrochloric acid concentration of the leaching solution. That is, the concentration of free hydrochloric acid in normal leaching waves is 6 to 8N, but this is diluted to 0.5 to 3N1, preferably IN
It was found that when solvent extraction was carried out after the pre- and post-treatment, a considerable amount of impurities remained in K without being extracted. Note that reducing the acid concentration by adding ammonia water for the recovery of platinum group elements as described above approaches the above-mentioned optimal total extraction concentration ((), and the ammonia water addition method is advantageous in this respect as well. Dilution of free hydrochloric acid is Partial neutralization with NaOH, adjustment to the target hydrochloric acid concentration by diluting the leachate with water, ion dialysis, etc. are used as appropriate. Although reductive precipitation may be used, it has been found that a considerable amount of the extracted impurities can be removed by scrubbing after the extraction process. This has the advantage of facilitating the reduction process using a reducing agent and saving the amount of reducing agent consumed for impurities.For scrubbing, water or 0.5-2N hydrochloric acid is used to reduce o/A = 1-2. , usually carried out at around 0/A = 1/1. Since phase separation is poor with water alone, it is preferable to use dilute hydrochloric acid. After this, a suitable reducing agent, preferably an organic reducing agent such as oxalic acid, dextrose or ascorbic acid, is added. The gold is reduced using
As a result, gold is reduced and precipitated. When using oxalic acid, 60-80'C1, preferably 2-80'C1 at around 70°C.
By shaking for 4 hours, gold is reduced and deposited on the gold plate, and the residual gold becomes substantially zero in both the solvent phase and the aqueous phase. The reduced crude gold thus obtained has a quality of 99.3 to 99.5%. Usually contains 100-300 ppm of Ag, etc.) CPt, Pd, Pb, Sb%As, se
,T. etc. exist in extremely small amounts. According to the invention, the gold is melted at 1100-1200 DEG C. in a non-contaminating container, such as a high purity graphite crucible produced by special atmosphere firing or the like. At this point, the total purity increases to 99.95%. 11
Below 00°C, the vapor pressure of chlorides, which are various impurities, decreases and it takes a long time to purify the loquat.On the other hand, when the temperature exceeds 1200°C, there is a concern about loss of gold, and a higher vapor pressure is not necessarily required. After that, a mixed gas of chlorine gas and inert gas is blown in. The cleaning effect is improved by simultaneously blowing inert gas rather than chlorine gas alone. The gas injection conditions are the amount to be treated,
It is determined by impurities, especially silver grade, blowing method, etc., but the general conditions are as follows: C1g gas oil inertness ratio 1 to 02 injection ratio 2Ag grade to 1 .100 hits or more (as Ag01) Blow time = 1 to 3 hours Typical inert gases include nitrogen, argon, etc. As a blowing method, a double pipe having an inner pipe and an outer pipe was used, and the chlorine mixed gas was blown through the inner pipe and the exhaust gas was discharged from the outer pipe, and the /lf result was obtained. Auf) There is almost no volatilization loss. Even if there is, there will be no problem if measures are taken to recover it from exhaust gas. A gc! It was confirmed that 1 was volatilized and no scum remained. In this way, more than 99,998% of the gold is refined and immediately made into molds and manufactured into products. No.11 decomposition and purification steps are involved at all. Reference examples, comparative examples, and examples are shown below.
Chlorine gas leaching from wf cargo) tMI8! Table 1: Copper electrolysis by-products produced in the refinery are decoppered using Fe'' ions.
The chemical composition of the decoppered product was obtained. (1) This jQf @ slurry is made into a slurry with a slurry concentration of 3751//'l using ~5 N Mail, and chlorine gas is blown into the slurry. ! leach was performed. The leaching depth was fixed at 60° C. and the leaching time was fixed at 6 hours. 1'c500c for the first 3 hours for chlorine gas injection
c/min/l slurry and half the amount for the remaining time. The chemical composition of the leachate after treatment is shown in Table 2. The Ag concentration in the leachate is very low, and the Ag
01 indicates that it is fixed in the leaching residue. Incidentally, the leaching rate of Au is as high as 99% or more in the case of 3NNa01. The Na11g degree should be optimally selected depending on the slurry concentration, leaching conditions, etc. (li) Mg is representatively selected from Group Ⅰ of the periodic table as a chloride other than Na11,) dgol, aqueous solution sludge IJ
- A load α output test was conducted. Here, 3N Mg
2 s o 9/l of the decoppered material using O1 solution.
slurry to a concentration of Raise the leaching temperature to 80℃,
C1 gas was continuously blown for 6 hours. The amount of blowing is 11/min/l slurry for the first 0 to 3 hours, and o, 5/min/l slurry for the second 3 to 6 hours! It was made into a slurry. The obtained leach wheel is shown in Table 3. Table 3 Reaction time Ag Ago l residue Au leaching rate (h)
Recovery rate (Kon (%) 0 - - 0.5 99,70 0.79 1 98, 99, 9.07 2 9 B, 44 79.52 3 97, 85 95.23 4 97.98 99. 87 6 9 g, 27 99.90 Since the slurry concentration is as low as 250 l/l, Ag01
It appears that the re-solubility of . Ag01 recovery can be increased by properly selecting the slurry concentration. In any case, in the leaching of materials in a metal chloride system, group II of the periodic table (Na5K, itb, etc.),
It has been demonstrated that good results can be achieved by selecting an appropriate element from Group II (Be, Mg, etc.). The leachate thus produced is one of the most suitable examples for treatment according to the invention. Comparative Example: Liquid obtained by leaching chlorine gas (composition, 11/l)
i3.2243Au, 0.3451mg, 0.056
3Pt. 0.2359Pd, 47.338e, 7.43Te,
19.81Pb. 7.23μS, 4.278b) was subjected to solvent extraction → acid washing → back extraction with oxalic acid to obtain reduced crude gold. The analytical values of this crude gold are 99.35%Au (+0.013%Ag. <0.0001%Pt, <0.0001%pa, <o,
oooi%pb, < o, oooi%8b, 0.
41% muro, 0.019% 8e. Q, 0096%To), and simply oxidize it (51/
m1n/3jlAu, 1200°C x 1h) The purity of gold was 99.94% Kup, but it still did not reach the predetermined 99.998% Kup. On the other hand, this refund K
Similar oxidation blowing was performed by mixing 8 equivalents of soda ash with Au Ic, but the gold purity was only 99.95%. Example 1 When conducting a purification test of reduced crude gold using the chloride volatilization method, it is extremely difficult to obtain several hundred yards of sample.
A sample having the following composition was prepared by adding predetermined impurities to high purity electrolytic gold (99,998%) 6011. Level, Si element Sample A Sample B Ag O,010,2 Se O,0B 0.08 1'e 0.01 0.01 pb O,0120,012 sb O,010,01 Test (υ;00 engineering %Ag grade crude gold sample (sample A) 2
00y is the inner diameter of 30. , φ×height 45u crucible α with lid
(made of IT￥l purity graphite) at 1200℃, and 1:101□+N11 mixed gas was added to this goldmine for 3 minutes.
The air was blown at a rate of 0.00 CC/min. As a result of performing chloride volatilization treatment for 3 hours, Ag = 3 ppm and all other impurities were 1 ppm or less. Also, the gold loading in this test was approximately 0.01%. Test +21; 0.2% (2000 ppm) Ag grade crude gold sample (sample B) approximately 20011 tested) fi+
It was purified under the same conditions. In particular, we tracked the reaction time of silver and obtained the following results. Time (hr) Au91g0 degrees (ppm) 0 20
00 1 1000 1.5 570 3.5 <2 After 3.5 hours of chlorine gas treatment, Ag containing a large amount of Au, medium and thick
Levels of <2 ppm K were reached. Other impurities are also 1
It became less than ppm. The volatilization loss of gold was less than 0.001%. Example 2 A 200 g crude gold sample of 0.01% λg grade was subjected to a refining test under the same conditions as in Example 1, except that the temperature of the gold mine was lowered to 100°C. According to the test results of continuously blowing Ol and L mixed gas for 3 hours, the Ag grade was 6 ppm and 2 ・p
It still took 3.5 hours to bring the temperature below pm. All other impurities were below 2 ppm. As described above, the present invention particularly targets electrolytic f
This is the first method to establish a method of refining to a purity of 99.998% or higher by omitting the Ivi1 step, and as a result, it is possible to eliminate the drawbacks inherent in electrolytic refining, as well as reduce the amount of K, stagnant gold in the plant, and W. -It was a significant success in reducing the size of Ura Time. Agent's name: Motoi Kurauchi, Hirodo Kurahashi, Akira Special Application No. 1983-65090 #i The details are amended as follows. t Page 6, line 6 [oo-1oooKJ and l'6
50-700°C". 2. On page 5, line 11, correct "J in the middle to r in the middle." Q! + 111tt59-65090 specification 1riP as follows 1111 stop so 1゜t 9th true, line 6 [PeJ and t jpt J
And d1 is correct.

Claims (1)

[Claims] 1) Solvent extraction and reduction of a gold-concentrated water bath solution (1) reducing the resulting reduced crude gold at a temperature of 1100 to 1200°C.
A method of recovering high-purity gold from K by melting it at a high temperature and blowing a mixed gas of chlorine gas and inert gas. 2) The gold-concentrated water bath liquid is a leaching liquid obtained by leaching copper electrolyte material or copper-removed dispersion that has been decoppered and arsenized with chlorine gas to condense the gold, as claimed in claim 1. Method described. 3) Salt fit gas leaching is carried out by slurrying the material with an aqueous solution of chlorides of metals from Groups 1 to 2 of the periodic table, and blowing chlorine gas into the slurry. Method described. 4) Prior to intoxicant extraction, the concentration of free hydrochloric acid in the leachate is 15
3. The method of claim 2, wherein .about.3NK is adjusted.