JP6651372B2 - Method for treating Sb-containing residue - Google Patents

Description

  The present invention relates to a method for treating an Sb-containing residue.

  In recent years, in the nonferrous metal smelting business, the ratio of recycled materials has increased, and the need to efficiently separate and collect accompanying rare resources has increased. Antimony (Sb) has been added as a flame-retardant aid for preventing ignition of electronic substrate debris and the like, and is one of the metals whose input to the copper smelting process is increasing.

  Antimony is distributed to the mat and slag in a smelting process, after which the mat is refined and cast into an anode. The anode is electrolyzed in the electrolysis step. During the electrolysis, part of the antimony contained in the anode is eluted into the electrolytic solution, and the remainder is distributed to the copper electrolytic deposit as an insoluble antimony compound. Since the noble metal is concentrated in the copper electrolytic deposit, the residue containing antimony generated in the process of treating the copper electrolytic deposit is returned to the smelting process in order to prevent loss of the noble metal.

  In the process of treating a copper electrolytic deposit by a wet method, first, copper is separated by oxidizing and leaching the copper electrolytic deposit in a sulfuric acid bath. Next, the decoppered copper electrolytic precipitate is leached with hydrochloric acid and hydrogen peroxide to dissolve gold, platinum, palladium, selenium, tellurium, antimony, and lead, and to separate silver as silver chloride and reduce it with iron. (Patent Documents 1 and 2).

  For the chloride leaching solution from which silver chloride has been separated, the hydrochloric acid concentration and the liquid temperature must be lowered in advance to avoid the precipitation of impurities in the tank and piping in the subsequent process and to improve the quality of the product. , Lowers the solubility of antimony, lead and tellurium and separates the precipitates formed. Precipitates of antimony, lead and tellurium are dissolved in the alkaline leaching step and neutralized with sulfuric acid to recover crude tellurium dioxide. Antimony and lead are not dissolved but are collected as a residue and re-input to the flash furnace (Patent Document 3).

  Gold, platinum, palladium, selenium, tellurium, etc. are separated and recovered from the filtrate obtained by separating antimony, lead, and tellurium from the solution after the chlorination leaching. On the other hand, the effluent containing the components that could not be separated is neutralized and then re-input into the flash furnace (Patent Documents 1 and 2).

JP 2001-316735 A JP 2001-316736 A JP 2011-68528 A

  In the chloride leaching step, a part of antimony is distributed to silver chloride, so that the recovery rate of antimony decreases in the next precipitation step.

  Further, in the alkali leaching step, the alkali leaching residue containing antimony after leaching tellurium is recharged into the flash smelting furnace, and the recharged amount of antimony to the smelting step increases.

  In view of the above problems, an object of the present invention is to provide a method for treating an Sb-containing residue that improves the Sb recovery efficiency from the Sb-containing residue.

In the method for treating an Sb-containing residue according to the present invention, the Sb-containing residue obtained by decoppering and leaching the copper electrolytic deposit in the copper smelting step is chlorinated and leached with hydrochloric acid and hydrogen peroxide, and the hydrochloric acid concentration during the chlorination leaching reaction is 4 mol / mol. L and a step of adjusting the concentration to exceed L, separating silver chloride from the solution after chloride leaching, and diluting the solution after chloride leaching containing antimony after the separation of silver chloride so that the hydrochloric acid concentration becomes 4 mol / L or less. It is characterized by comprising a step of adjusting and depositing a precipitate containing lead and antimony, and a step of obtaining an alkali leaching residue containing lead and antimony by solid-liquid separation after the precipitate is leached with alkali .

In this case, the concentration may be adjusted so that the hydrochloric acid concentration during the chloride leaching reaction is 5 mol / L or more. The solution after chloride leaching containing antimony after the separation of silver chloride may be adjusted so that the concentration of hydrochloric acid is 3 mol / L or less.

The liquid after chloride leaching containing antimony after separation of the silver chloride may be cooled. In this case, the solution after the chloride leaching containing antimony after the separation of the silver chloride may be cooled so that the solution temperature is less than 50 ° C. Alternatively, the solution after chloride leaching containing antimony after separation of the silver chloride may be cooled so that the solution temperature is 25 ° C. or lower .

  According to the method for treating an Sb-containing residue according to the present invention, the efficiency of recovering Sb from the Sb-containing residue can be improved.

It is a flowchart showing the process of treating a copper electrolytic deposit.

  FIG. 1 is a process chart showing a process of treating a copper electrolytic deposit. As illustrated in FIG. 1, the starting material is a copper electrolytic deposit.

(Copper removal process)
Various valuable substances are concentrated in the copper electrolytic deposit. This copper electrolytic deposit is repulped into a sulfuric acid bath, and air is blown in to oxidize and leach, whereby the copper electrolytic deposit is decopperized. Antimony (Sb) in the copper electrolytic precipitate becomes an oxide and remains in the decopperized precipitate.

(Chlorination leaching process)
The decoppered precipitate is subjected to chloride leaching with hydrochloric acid and hydrogen peroxide. As shown in the following chemical reaction formula, antimony reacts and dissolves with hydrogen peroxide.
H ₃ SbO ₃ + H ₂ O ₂ → H ₃ SbO ₄ + H ₂ O
Metals that cause chloride precipitation include silver, lead, and antimony.

  When the hydrochloric acid concentration exceeds 4 mol / L, the solubility of antimony and lead becomes very large. Therefore, the concentration of hydrochloric acid during the chlorination leaching reaction is adjusted so as to exceed 4 mol / L. Thereby, the separability between silver and antimony and lead can be improved. By adjusting the hydrochloric acid concentration during the chlorination leaching reaction to exceed 4 mol / L, the hydrochloric acid concentration of the solution after chlorination leaching also exceeds 4 mol / L. Thereby, antimony can be dissolved even in the solution after leaching with chloride. In addition, the hydrochloric acid concentration during the chlorination leaching reaction is preferably 5 mol / L or more, more preferably 6 mol / L or more.

  Separation of silver chloride and antimony is more effective when the temperature is higher than 50 ° C., since the higher the temperature of the solution after leaching of chloride, the better the separation.

(Deposition process)
Next, silver chloride is separated from the solution after chloride leaching, and the hydrochloric acid concentration of the solution after chloride leaching after separation of silver chloride is adjusted to 4 mol / L or less by dilution or the like. As a result, the solubility of lead and antimony decreases, and lead and antimony precipitate. In addition, the hydrochloric acid concentration of the solution after the chloride leaching after separating silver chloride is preferably 3 mol / L or less, more preferably 2 mol / L or less. Further, the liquid after leaching with chloride may be cooled. In this case, the liquid temperature of the liquid after chlorination and leaching by cooling is preferably lower than 50 ° C, more preferably 25 ° C or lower, and further preferably 5 ° C or lower. Thereby, the solubility of lead and antimony can be further reduced. There is no particular lower limit on the temperature of the solution after chlorination and leaching by cooling, and it may be in a range where the solution after chlorination and leaching does not freeze. As a result of X-ray diffraction analysis of a precipitate precipitated from the solution after the leaching of chloride, it is estimated that the form of lead is lead chloride and the form of antimony is an oxide or a tellurium compound.

(Alkaline leaching)
The deposited precipitate containing lead and antimony contains tellurium and selenium. For this purpose, alkali leaching is performed to dissolve and separate tellurium and selenium. The leaching condition is preferably leaching with an 80 ° C. alkaline solution composed of 30 to 60 g / L of NaOH. The slurry concentration is 100-200 g / L and the leaching time is 2-4 hours. By this method, selenium and tellurium can be leached, and antimony can be concentrated in the leaching residue (Patent Document 3). This leaching residue is an alkaline leaching residue.

(Reduction process)
Since the alkali leaching residue contains water, the amount of water is reduced by drying. For example, the alkali leaching residue is placed in a corrugated can or the like, and dried by a drying facility using steam heat. Next, the alkali leaching residue after drying is put into a melting furnace, and coke having a weight ratio of 0 to 10% based on the alkali leaching residue is put into the melting furnace. At this time, when the amount of sodium required for slag formation cannot be secured by the sodium in the alkaline leaching residue, soda ash (anhydrous sodium carbonate) may be added together with the alkaline leaching residue. The temperature of the melting furnace is preferably set to 1000 ° C. ± 100 ° C. In this case, the inside of the melting furnace becomes a weak reducing atmosphere. It is estimated that in a weak reducing atmosphere, sodium antimonate (NaSbO ₃ ) contained in the alkali leaching residue decomposes into sodium oxide and antimony oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ). The melting point of sodium antimonate (NaSbO ₃ ) is 1427 ° C., whereas the melting point of Sb ₂ O ₃ is 656 ° C. and the melting point of Sb ₂ O ₅ is 380 ° C. Further, the melting points of Sb ₂ O ₃ and Sb ₂ O ₅ are lower than the melting furnace. Therefore, dissolution of the alkali leaching residue can be promoted.

  Further, the addition of the coke can reduce the alkaline leaching residue. By the reduction, chlorine is removed from the chloride component in the alkali leaching residue, and separated into molten metal and molten slag. The molten metal includes Sb, Pb, Ag, and the like. The molten slag contains Se, Te, etc., together with Na, O, etc. contained in the alkali leaching residue and soda ash. Since dust generated from the melting furnace contains Sb, Pb, and the like, the dust is again charged into the melting furnace together with the alkaline leaching residue.

  The coke exists in a solid state within the temperature range of the melting furnace. If the alkali leaching residue does not dissolve, the above reduction will proceed by a solid-solid reaction. In this case, since good reactivity cannot be obtained, the reduction rate decreases. On the other hand, if the alkali leaching residue is dissolved, the above reduction proceeds by a solid-liquid reaction. In this case, since good reactivity is obtained, the reduction rate is improved.

  If the input amount of coke is too small, the reduction reaction of Sb becomes insufficient, so that Sb may remain in the slag. On the other hand, if the input amount of coke is too large, the reduction rate of Sb may decrease. Therefore, there is an optimum range for the amount of coke charged. The inventor's earnest research has revealed that the charging amount of coke with respect to the charging amount of the alkaline leaching residue into the melting furnace is preferably 5% to 30% by weight. In this range, the distribution ratio of Sb to the molten metal is particularly high.

  Therefore, in order to improve the reduction rate, it is preferable to additionally add coke to the melting furnace as needed. In this case, coke is charged so that the total amount (weight ratio) of coke to the alkali leaching residue to be charged into the melting furnace is 5% to 30%. More preferably, the total amount (weight ratio) of coke with respect to the alkaline leaching residue charged into the melting furnace is 10% or more and 15% or less. The amount of coke charged in the charging step is preferably equal to or less than the amount of coke charged in the smelting reduction step. Metallic Sb obtained in this step can be “Sb containing impurities” targeted in the present embodiment. Further, it is possible to bring the molten metal into the volatilization step.

(Soda treatment process)
However, depending on the impurities and the amount of the impurities, it may not be preferable to directly bring the molten metal to the volatilization step. For example, this is a case where Se, Te, As, and the like are included in large amounts. In this case, it is necessary to soda-treat the molten metal with a caustic soda solution. By soda treatment, Se, Te, As, etc. can be separated from the molten metal as scum. Since one or more of Pb, Ag, and Bi are contained as impurities in the molten metal, the metal after the soda treatment step is brought into the volatilization step as “Sb containing impurities” targeted in the present embodiment. It is also possible to bring the molten metal into the volatilization process.

(Volatile process)
The metal obtained by the smelting reduction and the metal obtained by the soda treatment are put into a volatilization furnace as “Sb containing impurities” and melted by heat. Further, by oxidizing the molten metal, Sb is oxidized to generate volatile Sb ₂ O ₃ . For example, Sb can be oxidized by blowing, blowing, or adding an oxidizing agent to the molten metal. Since Sb ₂ O ₃ is highly volatile, it is volatilized from the molten metal. Thereby, Sb can be recovered. For example, the temperature of the molten metal is preferably 660 ° C. to 700 ° C., and the amount of air blown to the molten metal is preferably 51 to 56 Nm ³ / h per 1 m ^{2 of the} surface of the molten metal. More preferably, the temperature of the molten metal is 680 ° C to 700 ° C. Further, by setting the Sb concentration in the molten metal to 50 mass% or less, preferably 40 mass% or less, generation of non-volatile Sb ₂ O ₄ , Sb ₆ O _{13 and the} like is suppressed, and Sb ₂ O ₃ is generated. Can be. When diluting the Sb concentration in the molten metal, a raw material having a low Sb quality (40 mass% or less) can be used. For example, it is preferable to use a raw material mainly composed of a low melting point metal such as Pb or Bi. However, since Pb has volatility, it is more preferable to use Bi. In addition, it is preferable that the volatile residue obtained by volatilization is returned to the melting furnace and subjected to reduction.

  According to the present embodiment, the Sb-containing residue obtained by decoppering and leaching the copper electrolytic precipitate is leached with hydrochloric acid and hydrogen peroxide, and the concentration of hydrochloric acid during the leaching reaction is adjusted to always exceed 4 mol / L. Thus, the solubility of antimony in the liquid after chloride leaching can be increased. Thereby, the separation between antimony and silver chloride can be improved. That is, since antimony distributed to silver chloride can be reduced, the recovery efficiency of antimony can be improved. In addition, the hydrochloric acid concentration during the chlorination leaching reaction is preferably 5 mol / L or more, more preferably 6 mol / L or more.

  According to the present embodiment, silver chloride is separated from the solution after chloride leaching, and the hydrochloric acid concentration of the solution after chloride leaching containing antimony containing silver chloride after separation is adjusted to 4 mol / L or less. The solubility of antimony in the liquid can be reduced, and the precipitate containing antimony can be recovered. The concentration of hydrochloric acid in the solution after leaching from silver chloride after separation of silver chloride is preferably 3 mol / L or less, more preferably 2 mol / L or less.

  Further, according to the present embodiment, by cooling the solution after the chloride leaching after separating the silver chloride, the solubility of antimony in the solution after the chloride leaching can be further reduced, and the precipitate containing antimony can be recovered. In addition, the liquid temperature of the solution after chlorination and leaching by cooling is preferably less than 50 ° C, more preferably 25 ° C or less, and further preferably 5 ° C or less.

After preliminarily adjusting the hydrochloric acid concentration of the solution after the chloride leaching, the solution was heated to 80 ° C., and then excessively added antimony chloride and lead chloride until a saturated state was reached, followed by stirring. Sampling was performed in the process of lowering the temperature to ° C., and the concentrations of dissolved antimony and lead were measured. The same treatment was performed on silver chloride, and the concentration of dissolved silver was measured. The solubility of antimony with respect to the hydrochloric acid concentration and the liquid temperature is as shown in Table 1. The solubility of lead with respect to the hydrochloric acid concentration and the liquid temperature is as shown in Table 2. The solubility of silver with respect to the hydrochloric acid concentration is as shown in Table 3.

  As shown in Tables 1 and 2, when the hydrochloric acid concentration of the solution after chlorination and leaching exceeds 4 mol / L, the solubility of antimony and lead becomes extremely large, and the amount of antimony contained in the copper electrolytic precipitate is defined as a reference amount. Antimony distributed to silver chloride was reduced from 33% to 19%.

  On the other hand, as shown in Table 3, the solubility of silver in the solution after chlorination leaching increased as the hydrochloric acid concentration increased, but even when the hydrochloric acid concentration was 4 to 5 mol / L, the silver concentration was 200 to 400 mg / L. Since it is about L, the distribution rate of silver to the solution after the chloride leaching is about 0.3% with respect to the amount of silver in the silver chloride, which does not significantly affect the recovery rate of silver.

  Thereafter, the concentration of hydrochloric acid in the solution after chloride leaching after separation of silver chloride was adjusted to 2 mol / L, and the solution temperature was cooled to 5 ° C. As a result, the solubility of antimony could be reduced, and a residue in which antimony was concentrated could be obtained by leaching the collected precipitate with alkali. The amount of antimony distributed to the residue was increased from 63% to 70% based on the amount of antimony contained in the copper electrolytic deposit.

  The form of antimony in the alkali leaching residue was sodium antimonate, and the antimony grade was around 40 mass%. The lead in the residue was considered to be lead hydroxide, and the lead quality was around 10 mass%.

  According to the above results, it has been clarified that the recovery efficiency of antimony can be improved by adjusting the concentration of hydrochloric acid during the chlorination leaching reaction to be more than 4 mol / L. In addition, it was clarified that by adjusting the hydrochloric acid concentration of the solution after chloride leaching after separating silver chloride to 4 mol / L or less, the solubility of antimony can be reduced and antimony can be precipitated. Furthermore, it was clarified that by cooling the solution after the chloride leaching, the solubility of antimony could be further reduced and antimony could be precipitated. Furthermore, it was found that by leaching the precipitate containing antimony and lead with alkali, tellurium can be separated and the quality of antimony in the leach residue can be increased.

  Further, the Sb-containing residue obtained by the alkali leaching step was put into a melting furnace, oxidized, and then reduced by adding coke. In the reduction, the melting furnace was maintained at 1000 ° C., and the reduction time was 8 hours. Further, the distribution ratio of Sb to the metal was confirmed with the addition ratio of coke to the residue being 5%, 10%, 15%, and 25% by weight. As a result, when the addition ratio of coke to the residue was 10% or 15%, the distribution ratio could exceed 80%, but it was less than 70% at 5% and 25%.

Further, a volatilization step was performed on the molten metal after the soda treatment step. For 7.1 ton of molten metal, the temperature of the molten metal was set to 680 ° C. to 700 ° C., the amount of air blown to the molten metal was set to 100 m ³ / h, and the spray position was set to a height of 20 mm to 40 mm from the surface of the molten metal. Sb can be recovered by oxidizing Sb to generate volatile Sb ₂ O _3. However, when the Sb concentration is reduced to 50% or less by adding a Pb electrolytic precipitate reducing metal with low Sb grade, At a better rate, Sb ₂ O ₃ could be volatilized. In addition, at that time, as a result of performing XRD analysis on components on the surface of the molten metal, it was confirmed that non-volatile Sb ₂ O ₄ , Sb ₆ O _{13 and the} like were not generated on the surface of the molten metal.

  As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the specific embodiments, and various modifications and changes may be made within the scope of the present invention described in the appended claims. Changes are possible.

Claims (6)

A step of leaching the Sb-containing residue obtained by decoppering and leaching the copper electrolytic deposit in the copper smelting step with hydrochloric acid and hydrogen peroxide, and adjusting the hydrochloric acid concentration during the chlorination leaching reaction to be more than 4 mol / L;
Silver chloride is separated from the solution after chloride leaching, and the solution after chloride leaching containing antimony after separation of silver chloride is diluted so as to have a hydrochloric acid concentration of 4 mol / L or less, and contains lead and antimony. Depositing precipitates;
After the alkaline leaching of the precipitate, a step of obtaining an alkaline leaching residue containing lead and antimony by solid-liquid separation,
A method for treating an Sb-containing residue, comprising:   The method for treating an Sb-containing residue according to claim 1, wherein the concentration of hydrochloric acid at the time of the chlorination leaching reaction is adjusted to be 5 mol / L or more.   2. The method for treating an Sb-containing residue according to claim 1, wherein the chlorination leaching solution containing antimony after separation of the silver chloride is adjusted to have a hydrochloric acid concentration of 3 mol / L or less.   The method for treating an Sb-containing residue according to any one of claims 1 to 3, wherein the solution after the chloride leaching containing antimony after separating the silver chloride is cooled.   5. The method for treating an Sb-containing residue according to claim 4, wherein the liquid after leaching with chloride containing antimony after separating the silver chloride is cooled to a temperature of less than 50C.   5. The method for treating an Sb-containing residue according to claim 4, wherein the solution after the chloride leaching containing antimony after separating the silver chloride is cooled to a temperature of 25 ° C. or lower.

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