JPH05311258A - Wet process treatment of copper electrolyzing anode slime - Google Patents

Abstract

PURPOSE:To efficiently recover the valuable matter, such as Ag, and to return the soln. after the treatment directly to an electrolysis stage by using an oxygen- enriched gas and specifying a leaching temp., oxygen partial pressure, free sulfuric acid concn. and slurry concn. CONSTITUTION:Valuable matter is recovered by a wet process from the anode slime produced from a copper electrolytic refining stage. The anode slime is put into an autoclave and is subjected to the leaching treatment under the conditions of >=180 deg.C liquid temp., <=200g/l slurry concn. and pressurization with the oxygen-enriched gas of >=5kg/cm<2> oxygen partial pressure in a sulfuric acid soln. of 100 to 200g/l free sulfuric acid concn. Since the decopperized slime after the leaching contains unleached Ag at a high level, the Ag is recovered by treating the slime with an ordinary method. Se, Te, etc., are recovered at a high yield from the inside of the liquid after the desilvering. The copper sulfate soln. after the treatment is returned directly to the electrolyzing stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet treatment method for anode slime produced in a copper electrolytic refining process. More specifically, it is a method for recovering valuable metals such as silver, selenium and tellurium by a wet method. It is about. This anode slime is a valuable material such as Ag, S
Although it contains e, Te, Au, Pt, etc., a dry method is generally used to recover these valuable materials.

[0002]

_2. Description of the Related Art Conventionally, as a purification method for separating Se and Te from an anode slime containing the above-mentioned valuables, the anode slime is sulphated or oxidatively roasted and Se is SeO ₂
Sublimation separation was performed, and the resulting roasted product was reduced and dissolved, treated with soda, and Te was separated from the soda (Na ₂ TeO ₃ ). However, with this method, the recovery rate of valuable materials is as low as about 50 wt%, and the generation of harmful gases such as SeO ₂ and SO ₂ cannot be avoided.

On the other hand, a method of recovering valuable substances from the anode slime by a wet method is also known. According to this method, the anode slime is leached by an autoclave in a solution to which H ₂ SO ₄ , FeSO _{4 and the} like are added (Nippon Mining Industry). Magazine,
Vol. 84, No. 963 (19688.7), No. 84
See pages 6-851). Here, iron sulfate is an oxidizing agent for dissolving Ni that is insoluble in sulfuric acid together with Cu from the anode slime, and avoids that the insoluble Ni becomes a semi-finished product containing a large amount of Au and Ag in the silver separating step. It is a thing. Further, AgCl separated from the autoclave leachate by adding HCl is replaced with Fe in an acidic HCl solution to form Ag metal.

Further, in the above method, hydrochloric acid is added to the autoclave leachate to precipitate silver chloride, and dissolved Se is blown with SO ₂ gas to be reduced and recovered as crude selenium.

However, in the above-described known wet recovery method for valuables, by adding iron ions to the solution of the anode slime, Ag, Se and Te are added.
Filtrate after recovery of valuable materials such as solids (for example, C
u50g / L, As7g / L, free H ₂ SO ₄ 100g
(Including / L) will contain Fe ²⁺ , Na, etc.,
Since the filtrate cannot be directly returned to the electrolysis step and a step of removing iron or the like is required, the process becomes complicated and the economy is low.

Also, in this known method, AgCl separated from the autoclave leachate is treated with Fe in an acidic HCl solution.
The material of the reaction tank for the replacement becomes a problem, and the cost therefor becomes a problem. Furthermore, the known method has a problem that the Se leaching efficiency is as low as 80 to 89 wt%.
The leaching rate of Te is as low as 70 to 80 wt%, and there is a similar problem.

Therefore, according to the present invention, the filtrate after recovery of valuable materials can be directly returned to the electrolysis step, and Se, T
It is an object of the present invention to provide a copper electrolytic anode slime treatment method using an autoclave, which is characterized by a high leaching rate of e and the like and that the requirement for corrosion resistance of the material of the tank is not high.

[0007]

As a result of various studies on the method of recovering valuable substances from anode slime, the present inventors have found that as a method of recovering Ag, Se, Te, the anode slime is in a sulfuric acid acid solution. At a liquid temperature of 180 ° C or higher, a free sulfuric acid concentration of 100 to 200 g / L, and a slurry concentration of 20.
The invention of a method characterized by carrying out a leaching treatment under a pressurized condition with an oxygen-enriched gas having an oxygen partial pressure of 0 g / L or less and an oxygen partial pressure of 5 kg / cm ² or more has been completed.

Anode slime is produced from a copper electrolysis process, and its composition is generally Cu: 20 to 30 w.
t%, As: 2 to 5 wt%, Te: 1 to 5 wt%, S
e: 5 to 15 wt%, Ag: 10 to 20 wt%, Au:
0.5-2 wt% and Pb: 5-10 wt%.

The results of autoclave leaching of anode slime in the above composition range under the following conditions will be described with reference to FIG. Slurry concentration: 50 g / L H ₂ SO ₄ concentration: 200 g / L Oxygen partial pressure: 5 kg / cm ² Rotation speed: 800 rpm Heating temperature (pressurized oxygen leaching temperature): 80 to 250 ° C.

FIG. 2 shows the leaching rate of each valuable component with respect to the pressurized oxygen leaching temperature. From the figure, it can be seen that when the pressure leaching temperature is 180 ° C., the leaching rate of valuable components, especially Se and Ag, rapidly increases. From this result, in the present invention, the pressure leaching temperature was limited to 180 ° C or higher.

When the pressurized gas in the autoclave is air, the pressure increases and the leaching rate tends to increase, but the leaching rates of Se, Te and Ag are low. On the other hand, by using an oxygen-enriched gas as the pressurized gas and setting the oxygen partial pressure to 5 kg / cm ² , the leaching rate is Cu:
99wt% or more, Ag: 85wt% or more, Se: 95w
Leaching is possible with t% or more and Te: 85 wt% or more. The oxygen enrichment rate is preferably 25% by volume or more.

If the concentration of the sulfuric acid acidic solution used for autoclave leaching is less than 100 g / L, the leached S
e ⁺⁴ , Te ⁺⁴ , Ag ⁺ , Cu ⁺² , As ⁺⁵ are hydrolyzed to form CuSeO ₃ , CuTeO ₃ , Cu (OH) ₂ , T
eO ₂ , Cu (AsO ₃ ) _{2 and the} like are produced, and these hydrolysis products hinder the leaching of valuables. On the other hand, the concentration is 2
If it exceeds 00 g / L, Fe and C in the anode slime
The leaching rate of valuable materials such as u and As decreases due to the common ion effect. As the sulfuric acid, a solution after removal of Ni from the copper electrolytic cleaning step can be used, but the Ni concentration is 20 g /
It is preferably L or less. This is because when the Ni concentration is higher than 20 g / L, the leaching rate of valuables decreases due to the effect of common ions (SO ₄ ^-2 , H ⁺ ).

Further, when the slurry concentration in the autoclave is higher than 200 g / L, the leaching rate of Ag, Cu, As, etc. decreases from the aspect of solubility, and it becomes difficult to recover valuable substances from the liquid after leaching.

Since the above-mentioned leached slime (referred to as "copper-free slime") contains a high concentration of unleached Au, it is processed in a usual fine gold and silver step to recover these valuables.

Silver chloride is obtained in the desilvering step in which HCl is added to the post-copper removal solution obtained by autoclave leaching.
Chloride ions are preferably added to the leachate at 1.05 times or more the chemical equivalent to fix Ag ¹⁺ as AgCl for desilvering.
Contact with chloride ions adds aqueous HCl. Alternatively, it is performed by simultaneously blowing Cl ₂ and SO ₂ . This is because it is desired to salify immediately after reduction. The amount of chlorine ions added is 0.34 to 0.36 kg per 1 kg of Ag,
The sodium thiosulfate solution has a concentration of 10 to 20 wt%,
Each is preferred. Electrolytic extraction conditions for Ag are usual.

By the above method, the Cl ⁻ concentration in the desilvered solution can be suppressed to 30 mg / l or less. The solid content (silver chloride) obtained after the subsequent solid-liquid separation is dissolved in a sodium thiosulfate solution, and silver is electrolytically collected from the obtained solution. 70 g of silver chloride was repulsed in 200 g / L-Na ₂ S ₂ O ₃ solution 1 L and stirred at room temperature for about 60 minutes,
Silver chloride is almost completely dissolved, and a silver solution having the following composition is obtained. Ag: 51.6 g / L Sb: 0.10 g / L As: 0.01 g / L

Electrodeposited silver can be efficiently recovered from a silver-sodium thiosulfate solution by ordinary silver electrowinning. The electrolysis conditions and electrolysis results are as follows, for example. Electrolysis conditions Cathode: Stainless steel (SUS316) Current density: 100 A / m ^{2 Between} electrodes (between electrode surfaces) Distance: 50 mm Electrolyte temperature: 25-28 ° C. Liquid circulation rate: 200 cc / min (electrolyte rate-4 L) Electrolysis result current Efficiency: 85% Electrolysis voltage: 2-3V (average) Electrodeposited silver grade: 99 wt% or more

Alternatively, the solid content and soda ash can be mixed to be carbonized, the silver carbonate can be thermally decomposed, and the silver metal can be separated and recovered from other valuable components. Carbonation by mixing with soda ash is preferably carried out at 700 to 1100 ° C. Separation and purification of silver in the fine gold and silver process.

[0019]

As described above, the valuable component can be leached in the autoclave at a high leaching rate by specifying the autoclave leaching temperature, using the oxygen-enriched gas, and specifying the oxygen partial pressure, free oxygen concentration and slurry concentration. Also, A
Since g is recovered by electrolysis or soda treatment through AgCl, the pH of the treatment solution can be efficiently recovered without excessively lowering the pH.

[0020]

Embodiments of the present invention will be described below with reference to the flow sheet of FIG.

The composition of the copper electrolysis anode slime (copper oxide) is Cu: 25.4 wt%, As: 4.3 wt%, T
e: 3.1 wt%, Se: 11.6 wt%, Ag: 1
8.4wt%, Au: 1.54wt%, Pb: 6.3w
The amount of the processing liquid and the like will be described below on the premise that it is 1%. In a SUS316 autoclave, 1 kg of the copper precipitate and the solution after Ni removal from the copper electrolytic purification step (free H ₂ SO ₄ : 200 g / L, N
10 g of i: 8.5 g / L) was added, heated to 190 ° C., oxygen partial pressure was set to 10 kg / cm ^2, and pressure was applied to perform leaching. The results are shown in Table 1.

[0022] (Table 1) Article matter leaching immersion ejection fraction (wt%) Experimental free slurry liquid amount Se Te Ag Cu As Pb Description acid concentration g / L wt% L ratio 1 50 50 10.6 70 80 85 80 90 0.3 Comparison 2 50 100 10.5 50 65 66 70 75 0.2 Example 3 50 200 10.4 42 35 41 62 53 0.1 4 100 50 10.6 93 92 93 95 95 0.2 5 5 100 100 10.5 80 87 60 85 90 0.1 Departure 6 100 200 10.4 60 80 50 80 85 0.1 7 200 50 10.6 99 90 91 99 98 0.2 Might 8 200 100 10.5 95 85 85 97 95 0.1 9 200 200 10.4 90 77 75 95 93 0.1 Ratio 10 300 50 10.6 95 75 80 99 97 0.1 Comparison 11 300 100 10.5 90 60 70 95 93 0.0 Example 12 300 200 10.4 85 30 50 90 90 0.0

[0023]

As described above, according to the present invention, silver can be recovered from the anode slime by the wet method, and the following advantages are brought about. (A) Since the copper sulfate solution after removing Ag, Se, and Te can be directly returned to the copper electrolysis step, the treatment efficiency is increased and the raw materials used can be reduced. (B) Further, Se and Te are recovered in the autoclave leachate in high yield. (C) Since it is easy to make the process continuous and automated, the number of days that gold and silver are stalled in the separation and purification process is greatly reduced, and labor can be saved.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention.

FIG. 2 is a graph showing the relationship between the pressure oxidation leaching temperature and the leaching rate.

Claims (1)

[Claims] 1. A method for recovering valuables by wet treatment of a copper electrolytic anode slime, wherein the anode slime is in a sulfuric acid acidic solution having a free sulfuric acid concentration of 100 to 200 g / L at a liquid temperature of 180 ° C. or higher and a slurry concentration of 200 g / L. A wet treatment method for a copper electrolytic anode slime, which comprises leaching under an oxygen-enriched gas pressure condition of L or less and an oxygen partial pressure of 5 kg / cm ² or more.