JPH0757895B2 - Oxidation leaching method of decoppered slime - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxidation leaching method of decopperized slime, more specifically, at the end point of the reaction when the oxidation-reduction potential of the slurry rapidly rises and then gradually rises. The present invention relates to a method of determining by

[Conventional technology]

Conventionally, for the end point determination of this type of oxidative leaching method, a method has been put into practical use in which the processing time of the raw material is sufficiently taken and the processing is performed for a considerably longer time than the actual processing.

In order to solve this problem, there has been proposed a method of stopping the reaction when the electrolytically precipitated copper is oxidatively leached in a sulfuric acid aqueous solution and the color of the slurry turns from black to white turbidity (JP-A-60-138026). Gazette).

However, this method has a problem in terms of accuracy because it is a visual judgment method, and there is a drawback in that a person must perform processing while monitoring.

[Problems to be solved by the invention]

It is an object of the present invention to provide an oxidative leaching process for decopperized slime that does not have the above mentioned drawbacks.

[Means for solving problems]

To achieve this object, the method of the present invention, when extracting decoppered slime with an aqueous sulfuric acid solution in the presence of an oxidizing agent such as air, oxygen, and hydrogen peroxide, the movement of the redox potential of the slurry is observed to The potential suddenly rises with the progress of the reaction, and the time point when the potential rises gradually becomes the end point of the reaction regardless of the magnitude of the redox potential.

[Action]

Decopperized slime is produced from decoppered electrolysis, which is a purification process of copper electrolytic refining, and the main components contained are Cu and As.
It is a slimy substance that accompanies b and Bi. Its main form is metallic copper and copper arsenide (Cu _X As _Y : for example Cu ₃ As).

The oxidation leaching reaction of decopperized slime is generally expressed as follows.

Generally, this leaching operation is performed by charging decoppered slime into a sulfuric acid aqueous solution in a leaching tank to form a slurry, and blowing air, oxygen or the like while stirring the slurry.

In the method of the present invention, the oxidation-reduction potential of the slurry sharply rises as the reaction progresses, and the end point of the reaction is defined as the end point of the reaction. According to the results of experimental confirmation that almost 100% by weight of both main components of slime, copper and arsenic, are leached.

As is well known, the content of valuables and impurities contained in decopperized slime varies considerably due to its nature, so the above-mentioned copper and arsenic are not always extracted close to 100% by weight. Irrespective of the size of the value, the leaching rate of the valuable material leveles off at least when the rapid increase in the redox potential stops.

Leaching conditions for carrying out the method of the present invention are not specified, but pulp concentration 50 to 300 g /, treatment temperature 60 ° C. or higher, initial acid concentration 100 to 500 g /, air blowing amount 0.2 to ² m ³ slurry / The range of minutes is preferred.

Among the above ranges, particularly the pulp concentration can be set to a considerably high concentration (twice or more of the above range) as long as the reaction is not hindered.

〔Example〕

 Examples will be described below.

Example 1 230 kg of decoppered slime containing 48.8% by weight of copper, 28.4% by weight of residual arsenic sulfur, etc. was charged into an aqueous solution of 1 m ³ containing 190 kg of sulfuric acid prepared in advance in a reaction tank to prepare a slurry, and a jacket was attached. The mixture was agitated with a flotation type agitator that automatically sucks air at, and the reaction temperature was maintained at 70 ° C for oxidative leaching.

The liquid temperature was initially warmed by passing water vapor through the jacket, but when the reaction started, the temperature rose due to the heat of reaction, so after that, the reaction temperature was adjusted by water cooling and this treatment was continued for 7 hours and 30 minutes, during which the slurry was oxidized. The reduction potential (hereinafter abbreviated as ORP) is continuously measured, and each time a part of the slurry is sampled to remove insoluble residues and Cu and As are quantified, and the leaching rate of each is determined from the amount of the slurry. Find the Cu and As leaching rate and
I sought a relationship with ORP. The average amount of sucked air during this period was 0.8 m ³ / min. The results are shown in FIGS. 1 and 2, respectively. As is clear from these figures, the rapid increase in ORP value in Fig. 1 stopped after 7 hours of treatment, and then changed to a gentle increase. At this point, the leaching rate of Cu and As (Fig. 2) It was found that the peak was reached and the end point of the reaction was suppressed.

This makes it possible to know the end point of the reaction by monitoring the ORP value and setting a set such as sounding an alarm and stopping the air supply so that the time when the sudden rise has ended can be automatically known.

Example 2 Sulfuric acid aqueous solution 1 containing 198 kg of decoppered slime containing 170% of sulfuric acid as a main component containing 50.8% by weight of Cu and 16.6% by weight of As 1
Oxidative leaching of valuables was performed in the same manner as in Example 1 except that m ³ and the average air suction amount were 1.2 m ² / min. The result is the third
Shown in Figures and 4.

As can be seen from FIGS. 3 to 4, even if the composition of the decoppered slime is different and the redox potential is different, according to the present invention, the accurate end point of the oxidative leaching can be known.

〔The invention's effect〕

Since the method of the present invention does not rely on the visual determination method as in the conventional method, the end point of oxidative leaching can be correctly known even by people who are far away or who are performing other work. Since it is not necessary to use useless power, there is an advantage that the reaction tank can be used efficiently.

[Brief description of drawings]

FIG. 1 is the processing time and ORP value of Example 1, FIG. 2 is the processing time of Example 1 and the leaching rate of valuables, FIG. 3 is the processing time and ORP value of Example 2, and FIG. It is a figure which shows the relationship between the processing time of Example 2, and the leaching rate of a valuable material.

Claims (1)

[Claims] 1. In a method of dissolving a decoppered slime in an aqueous sulfuric acid solution in the presence of an oxidizing agent to dissolve a soluble substance, the point at which the redox potential of the slurry is gently increased regardless of the magnitude of the redox potential. An oxidative leaching method of decopperized slime, which is characterized as the end point of the reaction.