JPH0421736B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to copper containing a large amount of impurities such as lead, zinc, bismuth, cadmium, arsenic, antimony,
This invention relates to a method for removing and recovering impurities such as tin by vacuum treatment. [Prior Art] In recent years, in copper smelting, the processing of ores with high impurity content has been increasing, and impurities in smelting intermediates such as produced slag, dust, and sludge are also increasing accordingly. A reduction smelting method is being considered as a method for recovering copper from these materials, but under strong reducing conditions to obtain a sufficient copper recovery rate, lead, zinc, tin, arsenic, It contains large amounts of elements such as antimony, bismuth, cadmium, iron, nickel, and cobalt. Therefore, if the copper smelting process is repeated in this manner, the amount of impurities circulated in the pyrometallurgical smelting process will increase, and the amount of impurities in the blister copper will increase, causing various troubles during electrolytic refining. Therefore, it is necessary to separate impurities from copper, which contains a large amount of impurities. In particular, relatively large amounts of lead, zinc, bismuth, antimony, arsenic, and tin are brought into copper smelting and concentrated during the refining or electrolysis process, so it is preferable to separate and recover them outside the smelting system. Conventionally, when separating zinc, lead, and tin from scrap, etc., which contains a large amount of impurities, they are melted together with slag, then coke and iron scrap are added in a converter, and smelted by blowing air to volatilize them. Although it is being collected, sufficient volatile recovery cannot be done at once.
A drawback was that a large amount of these metals circulated between the smelting furnace and the converter and could not be recovered economically. Also,
A flux treatment containing soda ash and limestone is a method for removing antimony and arsenic from blister copper, but in most cases copper is distributed into the generated flux salt;
Moreover, it was difficult to recover antimony and arsenic economically. [Problems to be Solved by the Invention] The present invention aims at removing harmful Pb, Zn, Bi,
The purpose is to provide a new method for efficiently separating and recovering impurities such as Cd, As, Sb, and Sn. [Means for Solving the Problems] The method of the present invention involves vacuum treating molten copper containing impurities in order to separate and recover impurities from copper, and then vulcanizing the molten copper to form a matte. Then, the produced pine is vacuum-treated in a molten state. When charging molten copper containing impurities into a vacuum processing container, when heating and melting copper charged at low temperature, or when adjusting the temperature to an appropriate temperature for processing in the next vacuum processing step, When returning the vacuum state to a normal pressure state, it is preferable to create an inert gas atmosphere such as N ₂ gas in the vacuum processing container in order to prevent oxidation of copper. The pressure inside the container when vacuum-treating molten copper containing impurities should be 25 mmHg or less, preferably 0.1 to 5.
It is desirable to set it to mmHg. An excessive increase in the degree of vacuum is unfavorable from the economic point of view of the exhaust system. In addition, the temperature of the molten copper at this time is preferably higher than the melting point and lower than 1350℃ in order to prevent splash caused by vacuum treatment.
Preferably below 1200℃. When vulcanizing the residual molten copper, it is preferable to vulcanize it at normal pressure in an inert gas atmosphere. Although high-grade sulfur can be used as a sulfur source, elemental sulfur is preferred in order to reduce the increase in the amount of processed material. Although a simple addition method may be used as the addition method, injection into the molten metal using a lance is effective for improving the sulfur yield. The amount of sulfur charged is 15% by weight of the 3 content of the produced pine.
If it is less than this, the mat and metal two-phase separation state will become noticeable and the volatilization of impurities will be insufficient, so it is preferable to add so that the S content of the produced matt will be 15% by weight or more. More preferably, in order to improve the volatility of Sb, the S content of the produced matte is
It is desirable to add it in an amount of 20 to 25% by weight. The pressure in the vacuum container during vacuum treatment of the produced mat is desirably 50 mmHg or less, preferably 0.1 to 5 mmHg, in order to sufficiently volatilize impurities such as As, Sb, and Sn. Further, the mat temperature at this time is preferably higher than the melting point and lower than 1200°C, preferably lower than 1100°C, in order to prevent splash caused by vacuum treatment. When vacuum processing molten copper or matte, the bath temperature should be kept as close to the melting point as possible when starting the vacuum processing to suppress the bumping phenomenon caused by gas generation at the start of the processing and to accelerate the rate of volatilization as the degree of vacuum increases.
It is important to gradually raise the temperature from the viewpoint of copper splash loss and economic efficiency of the vacuum evacuation system. Furthermore, since the rate of volatilization of impurities is controlled by the bath temperature, degree of vacuum, degree of stirring of the molten metal, etc., it is necessary to employ a system equipped with an appropriate stirring function. Further, dust consisting of impurities volatilized in these treatments is collected by a cyclone, a bath, a bag filter, etc., respectively. Dust consisting of Pb, Zn, Bi, Cd, etc., which was volatilized and collected during the vacuum treatment of molten copper, was processed during the lead and zinc smelting process, and dust consisting of As, which was volatilized and collected during the vacuum treatment of pine, was Dust consisting of Sn, Sb, etc. is treated in a separate treatment process including a leaching process and recovered as valuable materials. The material obtained by vacuum treating pine is processed in a copper smelting converter, etc. [Operation] When molten copper is vacuum treated, metal vapors such as Zn, Pn, Bi, Cd, etc. and some S are contained. In some cases, sulfide vapors evaporate, and when pine is vacuum treated,
Sulfide vapors such as As, Sb, and Sn evaporate and separate. [Example] Example 1 2000 g of blister copper (sample A, produced by reducing and melting slag, dust, and sludge from the copper smelting process) having the composition shown in Table 1 was melted in a vacuum melting furnace (high-frequency induction (heating method) and melted in a _N2 gas atmosphere. After the temperature of the molten copper reached 1120°C, evacuation was gradually started, and the vacuum treatment was continued until the generation of impurity vapor from the molten copper stopped as observed through the observation hole of the vacuum melting furnace. The ultimate vacuum level is
The vacuum treatment time was 30 minutes at 0.1 mmHg, and the temperature of the molten copper after treatment was 1300°C. A small amount of the molten copper after treatment was sampled and analyzed, and the results are shown in Table 2 (sample c). The volatility rates of Zn and Pb in this process are each 98
% by weight or more, and the volatilization rate of As, Sb, and Sn is 3%.
It was below. Next, after creating a N ₂ gas atmosphere in the vacuum melting furnace, sulfur was charged into the molten copper using a sulfur charging device to obtain matt (the analysis results of this matt are shown in Table 3. Sample E ). After maintaining the bath temperature of this mat at 1050° C., evacuation was gradually started and the vacuum treatment was continued until the generation of impurity vapor from the mat stopped. The ultimate vacuum degree was 0.5 mmHg, and the vacuum treatment time was 15 minutes. The analysis results of the pine after treatment are shown in Table 4 (Sample G). In this process
The volatilization rate of As and Sn was 98% by weight or more, and the volatilization rate of Sb was 78% by weight. Example 2 Scrap copper with the composition shown in Table 1 (Sample B)
2000 g was treated in the same manner as in Example 1 except for the following conditions. That is, the evacuation start temperature of the molten scrap copper was 1100°C, the ultimate degree of vacuum was 0.3 mmHg, the treatment time was 40 minutes, and the temperature of the molten copper after treatment was 1320°C. The analysis results of the molten copper after treatment are shown in Table 2 (Sample D). The volatility rates of Zn, Bi, and Cd in this process are
It was 99% by weight or more, and the volatilization rate of Pb was 97% by weight. Next, the analysis results of the pine obtained by vulcanization are shown in Table 3 (Sample F). This mat was subjected to vacuum treatment at an ultimate vacuum of 0.4 mmHg (the vacuum starting temperature and treatment time were the same as in Example 1).
Table 4 shows the analysis results of the pine after the treatment.
(Sample H) The volatilization rate of As and Sn in this step was 98% by weight or more, and the volatilization rate of Sb was 83% by weight.

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〔Effect of the invention〕

The effect of the present invention is that Pb, Zn, Bi, Cd, etc. and As,
Sn eutectoids in the electrolytic process of Sb, lead, and zinc smelting
By separating and recovering Pb, Zn, etc.
Dust containing Bi, Cd, etc. can be used as a raw material for existing lead and zinc smelting processes. In the conventional copper smelting process, it is possible to obtain dust containing high concentrations of Sn, As, Sb, etc., which are difficult to recover because they are contained in low concentrations in slag, so these can be economically recovered through a separate treatment process. . Moreover, there is almost no Cu loss, and the obtained refined pine can be directly used in the copper smelting converter process.

Claims (1)

[Claims] 1. A method for separating and recovering impurities from copper, which comprises vacuum-treating molten copper containing impurities, then vulcanizing the molten copper to form a matte, and vacuum-treating the produced matte in a molten state.