KR20070098455A - Method for recycling a platinum from a waste water comprising selenium using hydrazine - Google Patents

Abstract

A method for recovering platinum from waste fluid with selenium using hydrazine is provided to decrease the quantity of the repeatedly-treated platinum by realizing favorable recovering yield of a platinum-group element. In a method for recovering platinum from waste fluid with selenium using hydrazine, a platinum-group metal is recovered selectively from a solution by adding the hydrazine to the solution including at least one type of foreign materials, the selenium, and 4.0 g/L of platinum-group element or less. The concentration of platinum of the solution is less than 2.0 g/L, and the concentration of palladium thereof is less than 2.0 g/L. The concentration of the existed selenium is less than 10.0 g/L.

Description

Method for recovering platinum from waste liquid containing selenium using hydrazine {METHOD FOR RECYCLING A PLATINUM FROM A WASTE WATER COMPRISING SELENIUM USING HYDRAZINE}

1 is a flowchart showing a process of recovering a platinum group element or the like from a noble metal-containing residue.

[Document 1] Japanese Unexamined Patent Publication No. 2001-107156

[Document 2] Japanese Patent No. 3480216

[Document 3] Japanese Unexamined Patent Application Publication No. 10-102156

The present invention relates to a method for reducing and recovering a platinum group metal from an aqueous solution containing a relatively low concentration of the platinum group metal. In particular, the present invention relates to a method for efficiently recovering platinum-group metals (PGM) from a drainage solution generated in the process of purifying a noble metal-containing residue generated from a copper smelting process by a wet method. .

The present invention is particularly useful for the treatment of aqueous solutions containing at least one or more kinds of platinum group elements, selenium and other impurities in low concentrations.

The slag generated in the copper manufacturing process contains a significant amount of platinum, palladium and other platinum group elements. As a method of recovering and separating these platinum group elements, for example, Japanese Patent Laid-Open No. 2001-107156 discloses a method for extracting palladium using dialkyl sulfide from an aqueous solution containing palladium (Patent Document 1). In addition, Japanese Patent No. 3480216 discloses a separation method of platinum and ruthenium which selectively extracts platinum with tributylphosphate after dissolving slag in hydrochloric acid to adjust the redox potential to a specific range (Patent Document 2) Japanese Unexamined Patent Application Publication No. 10-102156 discloses a solution of platinum, tellurium, and copper which is neutralized with chloroplatinic acid solution under specific conditions and filtered, and after contacting with ammonium chloride after adjusting the acid concentration of the filtrate to a specific range. The separation method of is described (patent document 3).

However, the waste solution discharged from the extraction, filtration, washing process and the like contained a large amount of other impurities to be cut and a low concentration of platinum group metal was present. Although it is not suitable to dispose of them, the above conventional method is also not applicable, so it was recovered, recycled to the previous step, and repeatedly treated.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-107156

[Patent Document 2] Japanese Patent No. 3480216

[Patent Document 3] Japanese Patent Application Laid-Open No. 10-102156

The present invention aims to efficiently recover platinum group elements from an aqueous solution containing at least one or more kinds of platinum group elements, selenium and other impurities, and specifically, in the process of recovering platinum group elements and the like from a noble metal-containing residue. An object of the present invention is to efficiently recover a platinum group element, particularly platinum, contained in a waste solution.

The present invention relates to the following metal recovery method.

(1) A method for selectively recovering a platinum group metal from the aqueous solution by adding hydrazine to an aqueous solution containing at least one or more kinds of platinum group elements, selenium and other impurities and containing 4.0 g / L or less in the total amount of platinum group elements.

(2) The method of the above-mentioned (1), wherein the composition of the aqueous solution has a Pt concentration of 2.0 g / L or less, a Pd concentration of 2.0 g / L or less, and a more coexisting selenium concentration of 10.0 g / L or less.

(3) The method according to the above (1) or (2), wherein the concentration of selenium in the aqueous solution coexists with the concentration of platinum in the range of 5 to 100 times.

(4) The method as described in any one of said (1)-(3) which adds 50-200 reaction equivalent of hydrazine of the total amount of platinum group metals contained.

(5) The method as described in any one of (1)-(4) whose temperature of the said aqueous solution at the time of adding hydrazine is 70 degreeC or more.

(6) The method according to any one of (1) to (5), wherein the hydrazine is added in two or more times.

(7) The aqueous solution is any one of the following steps (a) to (e) which are carried out on the leaching liquor by leaching the residual amount of precious metals contained in the copper smelting process with sulfuric acid and / or hydrochloric acid. Metal recovery method in any one of said (1)-(6) which arises from:

(A) A step of contacting the leaching liquor with at least one solvent (A) selected from the group of dialkylcarbitol, methyl isobutyl ketone and isopropyl ether to solvent extraction of gold or reduction precipitation of gold for removal.

(B) reducing and recovering selenium and / or tellurium by contacting a leaching liquor or the treatment liquid of step (a) with at least one reducing agent (B) selected from the group consisting of sulfite gas, hydrazine, boron hydride and sodium borohydride.

(C) A step of extracting and recovering palladium by contacting a solution obtained by hydrochloric acid leaching the reduced residue of step (B) with at least one solvent (C) selected from the group of dialkyl sulfides (DAS), oximes and amines.

(D) back-extracting palladium from an aqueous ammonia solution from the treating solvent of step (c), crystallizing palladium from the aqueous palladium-containing ammonia solution, and filtering it; Palladium purification process which redissolves and recrystallizes palladium from this palladium containing ammonia aqueous solution, and filters it.

(E) Platinum is extracted by contacting the palladium extraction treatment after-treatment of step (c) with tributyl phosphate, and one kind selected from the group consisting of tributyl phosphate containing platinum and water or a highly dilute acid or alkaline solution. A step of back-extracting platinum by contacting a solution, and a step of filtering the ammonium platinum chloride precipitated by contacting an aqueous solution with ammonium chloride after back-extraction containing the platinum.

An example of the present invention will be described in detail with reference to a flowchart showing a process of recovering a platinum group element or the like from the noble metal-containing residue of FIG.

The noble metal-containing residues generated incidentally in the copper smelting step refer to, for example, raw materials other than the distillation residue of copper ore smelting containing the noble metal and the anode slime at the time of electrolytic smelting of copper.

Examples of methods used for leaching noble metal-containing residues include acid leaching, alkali leaching and water leaching, sulfuric acid leaching for removal of copper and tellurium, which are impurities during recovery of precious metals, and hydrochloric acid for removal of selenium. Leaching is preferred.

(A) Gold may be extracted by contacting the hydrochloric acid leaching liquid and at least one solvent (A) selected from the group of dialkylcarbitol, methyl isobutyl ketone and isopropyl ether, or gold may be removed by reduction precipitation. As the dialkyl carbitol of the solvent (A), dibutylcarbitol (DBC) is preferable for having a very large partition coefficient with respect to gold and having high selective extractability. In addition, oxalic acid or the like may be added to the hydrochloric acid leaching liquor to reduce gold to precipitate and remove it.

(B) The selenium and / or tellurium are reduced and recovered by contacting the leaching liquor or the treatment liquid of step (a) and at least one reducing agent (B) selected from the group consisting of sulfite gas, hydrazine, boron hydride and sodium borohydride. As the reducing agent (B), sulfurous acid gas, which is inexpensive and relatively easy to obtain, is preferred without consuming acid coexisting in the liquid.

(C) at least one selected from the group consisting of distilled hydrochloric acid (residue from which gold and / or copper and selenium and / or tellurium) and dialkylsulfide (DAS), oximes and amines Palladium is extracted and recovered by contacting a kind of solvent (C).

The concentration of hydrochloric acid in the treatment liquid of step (c) is preferably adjusted to 3 mol / L to 4 mol / L. If it is this range, extraction of remaining platinum and selenium can be suppressed and palladium can be selectively extracted.

Dioctyl sulfide, dihexyl sulfide, methyldecyl sulfide, t-butyl decyl sulfide, etc. are mentioned as dialkyl sulfide of a solvent (C). Dihexyl sulfide (DHS) is preferable because of the high partition coefficient for palladium and high selectable extraction.

The concentration of the dialkyl sulfide in the solvent (C) is, for example, 15 to 60 vol%, preferably 20 to 50 vol%. If the amount is less than 20 vol%, the throughput increases due to the decrease of the loading capacity, and the process management becomes difficult. If the amount exceeds 50 vol%, the phase separation becomes difficult due to the increase of the specific gravity. . Moreover, when dialkyl sulfide is less than 4 mol times with respect to the amount of palladium in the raw material liquid of a process (C), sufficient extraction effect cannot be acquired. On the other hand, if this amount exceeds 10 molar times, the effect is saturated.

(D) If the solvent (C) containing palladium is scribed from the treating solvent of step (c) with an aqueous hydrochloric acid solution and the accompanying impurities are removed as hydrochloric acid drainage (I ₁ ), and back-extracted with ammonia water, Palladium can be obtained by dissolving in ammonia aqueous solution as a dichloroammine palladium complex {[Pd (NH ₃ ) ₂ ] Cl ₂ }. When dichloroamminepalladium is crystallized by adding an aqueous hydrochloric acid solution to the amminepalladium solution and filtered, drainage (I ₂ ) is generated as a filtrate. The obtained palladium crystallization salt is crystallized again for further purification. The dichloroammine palladium recrystallized salt generated at this time is filtered and dissolved by heating to obtain sponge-like palladium. Along with the filtration of this palladium recrystallization, the waste water I ₂₃ is generated as a filtrate.

(E) Platinum is extracted in TBP by contacting the treatment liquid (residue from which palladium has been removed) of step (c) with tributyl phosphate (TBP). In this case, by adjusting the hydrochloric acid concentration of the residual liquid from which palladium has been removed to about 5 prescribed amounts and contacting with tributyl phosphate, extraction of bismuth can be suppressed to promote extraction of platinum. Drainage (II) is generated as a residual liquid after extraction.

Tributyl phosphate containing extracted platinum is scribed with hydrochloric acid, and impurities such as Cu, Bi, Se, Pb and Pt contained in tributyl phosphate are transferred in hydrochloric acid drainage (III). When the concentration of the hydrochloric acid aqueous solution to be scribed is 4 to 5.5, bismuth ions extracted with platinum can be transferred to hydrochloric acid drainage and separated from platinum ions in tributyl phosphate.

Tributyl phosphate washed with hydrochloric acid is brought into contact with water or a highly dilute acid or alkaline solution to back extract the chloroplatinic acid into an aqueous phase to obtain an aqueous chloroplatinic acid solution.

The obtained aqueous platinum chloride solution was adjusted to alkalinity, and the precipitates containing Cu, Te, etc. generated by neutralization were filtered. Get by The filtrate is a drain (IV). Sponge-like platinum can be obtained by roasting the obtained ammonium platinum chloride in air | atmosphere.

The aqueous solution of the present invention may contain a solid matter, a washing drainage of an organic phase, and the like, in addition to the above-mentioned wastewater (I) to (IV).

The platinum group element total amount of aqueous solution becomes 4.0 g / L or less normally through the (a)-(e) process of hydrochloric acid leaching after-treatment of the noble metal containing residue which is incidentally produced in the said copper smelting process.

The composition of the aqueous solution is Pt, for example, 0.01 to 2.0 g / L, preferably 0.1 to 0.5 g / L, and Pd, for example, 0.1 to 2.0 g / L, preferably 0.1 to 0.5 g / L.

In this aqueous solution, selenium coexists, for example, 0.01 to 10.0 g / L, preferably 0.01 to 3.0 g / L.

The present invention adds at least 50 to 200 reaction equivalents, more preferably 100 to 150 reaction equivalents of hydrazine, of the amount of platinum contained in the aqueous solution to at least one kind selected from the group of platinum group elements, selenium and other impurities. It is collected by filtration as a precipitate.

Hydrazine is a strong reducing agent and can be crystallized in aqueous solution by reducing platinum group elements, selenium and other impurities.

Here, the reaction equivalent means the chemical reaction equivalent weight of platinum in each element of the platinum group metal contained in the aqueous solution. If it is less than 50 reaction equivalents, the recovery rate of the target platinum group element will fall, and even if it exceeds 200 reaction equivalents, since an effect cannot be expected further, it is unpreferable.

Hydrazine may be used in a commercially available concentration of about 60% by weight.

The temperature of the said aqueous solution at the time of adding hydrazine is 50 degreeC or more, Preferably it is 70 degreeC or more. The upper limit is the boiling point of the aqueous solution, and if it is less than 50 ° C, the recovery of platinum is lowered. In addition, since selenium in the liquid is reduced and precipitated in a poor filterability, it is not industrially preferable.

When the hydrazine is added to the acidic solution, the reaction is vigorous, and therefore it is preferable that the hydrazine is added in two or more times instead of once. Although the addition method does not limit this invention, you may add sequentially, for example, dividing into two times or more continuously, stirring. After hydrazine addition, it is preferably stirred for 2 to 4 hours.

Filtration at the completion of crystallization yields a solid comprising platinum group elements, selenium and other impurities. The obtained solid can be separated and purified by the usual method to obtain a product.

The present invention will be described in more detail with reference to the following Examples.

(First embodiment)

500 mL (pH 0.1, hydrochloric acid stock solution containing platinum (0.16 g / L), palladium (0.02 g / L), selenium (3.25 g / L) and tellurium (0.01 g / L) obtained as a filtrate after platinum crystallization Hydrochloric acid concentration of 3.7) was heated at 80 ° C, and 1.0 ml of hydrazine (concentration: 60 mass%) manufactured by Mg Otsuka Chemical Co., Ltd. was added dropwise. After stirring at 80 ° C for 1 hour, 1.0 ml of hydrazine was further added dropwise. The total amount of hydrazine was 100 times the Pt reaction equivalent. Moreover, solid content (reduced residue) obtained by filtering and drying after stirring at 80 degreeC for 1 hour was 1.25g. Table 1 shows the results of the recovery of each element from the stock solution.

(2nd Example)

The same procedure as in Example 1 was carried out except that 0.5 ml of hydrazine was added dropwise twice and the total hydrazine amount was 50 times the Pt reaction equivalent. The results are shown in Table 1.

(Third Embodiment)

Stirring was carried out at room temperature (about 20 ° C) without heating the stock solution, and the same treatment was conducted as in the first example except that the mixture was stirred for 23 hours after the addition of the second hydrazine. The results are shown in Table 1. Seven hours after the recovery, a precipitate formed from the filtrate.

(Example 4)

The same procedure as in Example 1 was carried out except that 82 ml of a 25% aqueous sodium hydroxide solution was added to adjust the pH of the stock solution to 7.0 before the addition of hydrazine. The results are shown in Table 1.

Table 1

Total hydrazine reaction equivalent Temperature Recovery Pt standard Metal total basis (℃) Pt (%) Pd (%) Se (%) Te (%) First embodiment 100 1.95 80 97 98 90 6 Second embodiment 50 0.97 80 70 68 58 - Third embodiment 100 1.95 Room temperature 83 99 72 14 Fourth embodiment 100 1.95 80 79 98 67 100

From Table 1, the second example in which 50 reaction equivalents of hydrazine was added on a platinum basis was lower in recovery than the first example of 100 reaction equivalents. Also, the third embodiment in which hydrazine was added at room temperature (about 20 ° C.) also had a deterioration in recovery rate other than palladium. In the fourth example in which an aqueous sodium hydroxide solution was added before the addition of hydrazine, the recovery of platinum and selenium was lowered, while the recovery of tellurium was 100%.

According to the present invention, since the platinum group element, selenium and other impurities can be directly reduced from an aqueous solution containing at least one or more kinds even under acidic conditions to obtain a solid containing platinum group metal, it is repeated by achieving a high recovery rate of the platinum group element or the like. The amount can be reduced.

Claims (7)

A method for selectively recovering a platinum group metal from the aqueous solution by adding hydrazine to an aqueous solution containing at least one or more kinds of platinum group elements, selenium and other impurities and containing 4.0 g / L or less in the total amount of platinum group elements. The method according to claim 1, wherein the composition of the aqueous solution has a Pt concentration of 2.0 g / L or less, a Pd concentration of 2.0 g / L or less, and a coexisting selenium concentration of 10.0 g / L or less. The process according to claim 1 or 2, wherein the concentration of selenium in the aqueous solution is 5 to 100 times the concentration of platinum in the coexisting platinum group metal, in particular. The method according to any one of claims 1 to 3, wherein 50 to 200 reaction equivalents of hydrazine of the total amount of platinum group metals included are added. The method of any one of Claims 1-4 whose temperature of the said aqueous solution at the time of adding hydrazine is 50 degreeC or more. The method according to any one of claims 1 to 5, wherein the hydrazine is added in two or more times. The aqueous solution according to any one of claims 1 to 6, wherein the aqueous solution is carried out with respect to the leaching liquor by leaching noble metal-containing residues generated incidentally in the copper smelting process with sulfuric acid and / or hydrochloric acid. (A) contacting the leaching liquor with at least one solvent (A) selected from the group of dialkylcarbitol, methyl isobutyl ketone and isopropyl ether to remove gold by solvent extraction or reduction precipitation of gold; (B) reducing and recovering selenium and / or tellurium by contacting the leaching liquor or the treatment liquid of step (a) with at least one reducing agent (B) selected from the group consisting of sulfurous acid gas, hydrazine, boron hydride and sodium borohydride; , (C) extracting and recovering palladium by contacting a solution obtained by hydrochloric acid leaching the reduced residue of step (b) with at least one solvent (C) selected from the group of dialkyl sulfides (DAS), oximes and amines; (D) back-extracting palladium with an aqueous ammonia solution from the treating solvent of step (c), crystallizing palladium from this aqueous palladium-containing ammonia solution, and filtering the separated palladium; A palladium purification step of re-refining palladium from the palladium-containing ammonia aqueous solution and filtering it; (E) Platinum is extracted by contacting the palladium extraction treatment after-treatment of step (c) with tributyl phosphate, and one kind selected from the group consisting of tributyl phosphate containing platinum and water or a highly dilute acid or alkaline solution. The method which arises from the process of any one of the process of contacting a solution back-extracting platinum, and the process of filtering the ammonium platinum chloride precipitated by contacting aqueous solution and ammonium chloride after back-extraction containing this platinum.

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