JP4158706B2 - Processing method and manufacturing method for separating gold from platinum group-containing solution - Google Patents

Description

  The present invention relates to a treatment method capable of efficiently precipitating and separating gold remaining in a platinum group-containing solution obtained from a treatment process of a selentellurium platinum group-containing material. The treatment method of the present invention is suitable as a demetalization method for separating and recovering selenium tellurium and the platinum group from a reducing soot obtained by reducing a solution after gold extraction in a process of recovering noble metal from copper electrolytic slime. . In the present invention, the selenium tellurium platinum group-containing material means a material containing at least one of selenium and tellurium and one of the platinum group elements. Selenium tellurium refers to selenium and / or tellurium.

  In the copper electrolysis process in copper refining, impurities insoluble in the electrolytic solution are by-produced as a residue. This by-product contains a considerable amount of platinum group elements such as gold, silver, copper, Pt, Rh, and Ru, Se, and Te, and many methods for separating and recovering these noble metals have been proposed. Yes. For example, the copper removal slime is leached with chloride, silver and lead are recovered from the leach cake, and gold is recovered from the leachate by solvent extraction. This post-gold extraction solution contains Se and Te together with platinum group elements. Therefore, sulfur dioxide gas is introduced into the solution after gold extraction and reduced, and the selenium soot previously precipitated is distilled to separate and recover high-purity selenium, and the distillation residue is further subjected to alkali melting treatment to obtain a selenium-containing leachate. Separated into platinum group-containing residues, while further introducing sulfurous acid gas into the above-mentioned post solution and precipitating tellurium soot, this tellurium soot was alkali leached to obtain selenium tellurium-containing leachate and platinum group containing Selenium, tellurium and platinum group elements are recovered from these leachates or leach residues.

  In such a precious metal recovery processing system, a solvent extraction method using dibutyl carbitol (DBC) has been known as a gold recovery method (Patent Document 1). An aqueous oxalic acid solution is added to the gold extract to reduce and deposit gold (Patent Document 2). However, in the solvent extraction method using DBC, about 0.3% of the solvent remains in the solution after extraction. Although this residual solvent is distilled and separated, a small amount of gold contained in the solvent remains, so that it is required to efficiently recover this gold in a subsequent step.

  In addition, oxalic acid is added to the leaching solution of copper electrolytic slime, and the resulting precipitate is treated with nitric acid and heated and melted (Patent Document 3). Bis (2-butoxyethyl) ether is added to the leaching solution of copper electrolytic slime. A method is known in which gold is mixed and extracted into an organic phase, and this organic phase is washed with hydrochloric acid and then reduced using oxalic acid (Patent Document 4). However, the method of selectively reducing gold using oxalic acid has a problem that when the chlorine concentration in the chlorine leaching solution of the copper electrolytic slime is high, the reaction rate is remarkably slow, and the gold cannot be substantially reduced.

On the other hand, a method using hydroxylamine hydrochloride, nitrous acid, or sulfurous acid as a reducing agent for extracting gold from a gold-containing material is known (Patent Document 5). In addition, a method of using alkylhydroxyamine as a complexing agent when electroplating a metal substance containing palladium, gold or the like is also disclosed (Patent Document 6). However, gold contained in the solution after copper extraction of copper removal slime is in a very small amount and contains a larger amount of tellurium, selenium, platinum group elements, etc. than gold. Even if the alkylhydroxyamine is added directly, it is difficult to efficiently recover gold.
JP-A-57-79135 JP 2001-316735 A Japanese Patent Publication No. 64-3930 Japanese Patent No. 3087758 Japanese Patent Laid-Open No. 2-97626 Japanese Patent Laid-Open No. 2-2211392

  The present invention overcomes the above-mentioned problems of conventional gold recovery methods for the selenium tellurium platinum group-containing materials obtained from the treatment process of the leaching solution of the decoppered electrolytic slime, and the gold contained in the selenium tellurium platinum-containing material. It is intended to provide a method for efficiently separating and recovering the product.

The present invention relates to a treatment method for separating gold from a platinum group-containing solution having the following constitution.
(1) The selenium tellurium platinum group-containing material is alkali-treated to separate a selenium tellurium-containing leachate and a platinum group-containing residue, and hydrochloric acid is added to the platinum group-containing residue in the presence of an oxidizing agent to dissolve the platinum group element. A treatment method for separating gold from a platinum group-containing solution, wherein hydroxylamine hydrochloride is added to the platinum group-containing solution which has been liquid-separated and filtered to selectively reduce and deposit gold.
(2) Alkali leaching treatment or alkali melting treatment is carried out as an alkali treatment of the selenium tellurium platinum group-containing material, and hydrochloric acid is added to the platinum group-containing residue obtained by this alkali treatment in the presence of an oxidizing agent to dissolve the platinum group element. The treatment method according to (1) above, wherein hydroxylamine hydrochloride is added to the platinum group-containing solution separated by filtration to selectively reduce and precipitate gold.
(3) A selenium tellurium platinum group-containing material is mixed with an alkali solution of 1 mol / L or more and subjected to an alkali leaching treatment for leaching selenium and tellurium at a temperature of 60 ° C. or more. Separated into leachate and platinum group-containing residue, or added a mixture of caustic soda and sodium nitrate to selenium tellurium platinum group-containing material, heated above the melting temperature of the mixture to dissolve selenium tellurium, and alkaline melting to leach water The treatment method according to the above (1), wherein the treatment separates the selenium tellurium-containing leachate and the platinum group-containing residue and dissolves the separated platinum group-containing residue.
(4) Use the post-gold extraction liquid of the precious metal recovery treatment system for decopperized electrolytic slime as the selenium tellurium platinum group-containing material, introduce sulfurous acid gas into this post-liquid solution, reduce it, and distill the selenium soot previously precipitated. The distillation residue from which high-purity selenium was separated was alkali-melted to separate the platinum group-containing residue. On the other hand, the tellurium soot precipitated by introducing sulfurous acid gas into the above-mentioned liquid was further alkali-leached to contain the platinum group. The residue is separated, and hydrochloric acid is added to these platinum group-containing residues in the presence of an oxidizing agent for solid-liquid separation, and hydroxylamine hydrochloride is added to the filtrate to selectively reduce and deposit gold, as described in (1) above. Processing method.
(5) A method for producing gold in which the reduced deposit obtained by the treatment method described in any one of (1) to (4) above is washed, dried, heated and melted and cast into an ingot.

[Specific description]
The present invention will be specifically described below.
An outline of the treatment method of the present invention is shown in FIG. As shown in the figure, this treatment method is performed after alkali treatment of a selenium tellurium platinum group-containing material to separate a selenium tellurium-containing leachate and a platinum group-containing residue, and after adding hydrochloric acid to the platinum group-containing residue in the presence of an oxidizing agent. This is a treatment method for separating gold from a platinum group-containing solution, wherein hydroxylamine hydrochloride is added to the platinum group-containing solution separated by solid-liquid separation and filtered to selectively reduce and deposit gold.

Selenium tellurium platinum group-containing material The treatment method of the present invention can use, as a raw material, a selenium tellurium platinum group-containing material obtained in a copper smelting step. Specifically, for example, the reduction residue of the extraction residue obtained by separating the gold from the hydrochloric acid leaching solution of the copper-free electrolytic refining slime by solvent extraction, such as rhodium, ruthenium, palladium, iridium, platinum group elements such as platinum, gold, It contains a large amount of valuable metals such as silver, selenium and tellurium. Therefore, the treatment method of the present invention can use a reduction treated soot of decoppered electrolytic slime as a starting material.

  Specifically, for example, the copper removal refining slime is processed as follows. First, the decopper refining slime is slurried with hydrochloric acid and hydrogen peroxide, and is filtered to separate into a leach cake containing mainly silver and a leach solution containing gold, platinum group elements, selenium and tellurium. Next, the liquid property of the leachate is adjusted, and gold is separated from the leachate by solvent extraction using DBC or the like. Platinum group elements, selenium, tellurium, and the like are dissolved in the extraction residue after separation of gold in this manner. Therefore, sulfur dioxide, specifically, for example, sulfurous acid gas is introduced into this extraction residue in an amount that keeps the concentration of selenium in the solution at 3 g / L or more, thereby reducing and precipitating selenium and separating it from the extraction residue. . Further sulfur dioxide is introduced into the filtrate from which selenium has been separated, and tellurium is reduced and precipitated together with the remaining selenium. Platinum group elements are precipitated together with selenium and tellurium. This can be filtered off to obtain a platinum group containing selenium tellurium.

  In the reduction treatment of the solution after the gold extraction, when selenium and tellurium are reduced and precipitated, tellurium has a reduction potential lower than that of selenium, and tellurium precipitates after selenium precipitates. Selenium and tellurium can be separated and recovered by adding sulfur dioxide to the filtrate to precipitate tellurium.

  In the present invention, as the selenium tellurium platinum group-containing material, the above-mentioned gold-extracted solution-reduced soot and further distilled soot can be used. In addition, a solution containing selenium tellurium and a platinum group such as plating factory effluent and smelting effluent can be used as the selenium tellurium platinum group-containing liquid.

Alkaline treatment step The selenium tellurium platinum group-containing material thus obtained is alkali-treated to separate into a selenium tellurium-containing leachate and a platinum group-containing residue. As the alkali treatment, any one or both of (a) alkali leaching treatment and (b) alkali melting treatment can be performed. When both alkali leaching treatment and alkali melting treatment are performed, the selenium soot previously precipitated by reduction of the above extraction residue is distilled to recover high-purity selenium, and the residue (distilled residue) is subjected to alkali melting treatment. Then, it is preferable to subject the precipitated tellurium soot to alkali leaching. This distillation residue forms a compound such as palladium selenide, and is stable, so that selenium does not elute even when alkaline leaching occurs. Selenium can be efficiently treated by subjecting the distilled water to an alkali melting treatment. On the other hand, rhodium and ruthenium in tellurium are relatively higher in quality than those contained in selenium soot, so that when they are alkali-melted, they tend to be insoluble oxides and later leaching of hydrochloric acid becomes difficult. Therefore, tellurium is preferably subjected to alkali leaching treatment.

(A) Alkali leaching treatment The selenium tellurium platinum group-containing material is mixed with an alkali solution such as a caustic soda solution to perform alkali leaching. The alkali leaching is preferably carried out under an alkali concentration of 1 mol / L or more, and for example, a range of 5 mol / L to 8 mol / L is preferable. By making the alkali concentration 1 mol / L or more, it becomes strong alkalinity of pH 14 or more, the oxidation-reduction potential of selenium and tellurium is lowered, and selenium and tellurium are eluted in an alkaline solution without using an oxidizing agent under normal pressure. Can do. Since the elution reaction of selenium and tellurium is slow at room temperature, it is appropriate to perform leaching at a temperature of 60 ° C. or higher, preferably 60 to 90 ° C., more preferably about 80 ° C.

  By the alkali leaching, selenium and tellurium are eluted in the alkali solution and dispersed in a colloidal form. On the other hand, platinum group elements such as rhodium and palladium remain without being eluted. This is filtered and separated into a leachate containing selenium or tellurium and a solid containing a platinum group element.

  After neutralization by adding sulfuric acid or hydrochloric acid to the filtrate (leachate) containing selenium tellurium after the above solid-liquid separation, a black precipitate of metal selenium or metal tellurium is formed, and the color of the solution gradually decreases from dark purple to a liquid near pH 7. Becomes transparent. The grade of this selenium precipitate or tellurium precipitate is approximately 99% or more, and high grade metal selenium or metal tellurium can be recovered. When nitric acid is used instead of sulfuric acid or hydrochloric acid, selenium and tellurium are oxidized and dissolved by the oxidizing power of nitric acid, and cannot be precipitated. The liquid temperature is preferably 60 to 80 ° C. When neutralized at this liquid temperature, metallic selenium having good filterability can be obtained.

On the other hand, an oxidizing agent such as hydrogen peroxide is added together with hydrochloric acid to the solid content containing the platinum group to elute platinum group elements such as platinum, palladium, rhodium and ruthenium. The platinum group element is oxidized by hydrogen peroxide and becomes a chloride complex by chlorine ions, and is stabilized and eluted in the liquid. Hydrogen peroxide uses the equivalent amount necessary to convert the platinum group element into ions having a stable oxidation number, that is, the equivalent amount required to oxidize platinum to tetravalent, palladium to bivalent, and rhodium and ruthenium to trivalent. . It is preferable to use hydrochloric acid in an amount corresponding to PtCl ₆ ⁻ , PdCl ₄ ⁻ , RhCl ₆ ³⁻ , RuCl ₆ ³⁻ , and 2 mol / L or more as free hydrochloric acid. The reaction temperature is preferably 60 ° C. or higher for promoting the reaction, and is suitably 80 ° C. or lower for suppressing the decomposition of hydrogen peroxide, preferably at about 70 ° C. By this dissolution treatment, a hydrochloric acid solution in which platinum, palladium, rhodium, ruthenium and the like are dissolved can be obtained.

  As described above, selenium and tellurium are dissolved without using an oxidizing agent under normal pressure by mixing the selenium tellurium platinum group-containing material with a strong alkali solution and leaching the alkali at a temperature of about 60 ° C. to 90 ° C. The selenium and tellurium can be separated and recovered by neutralizing the leachate containing selenium and tellurium with sulfuric acid or hydrochloric acid. Moreover, approximately 95% or more of the platinum group element can be separated as a solid content. In addition, since the platinum group element is not oxidized during the alkali leaching, hardly soluble rhodium oxide or ruthenium oxide is not generated, so that the solution can be easily formed. A platinum group element-containing liquid can be obtained by oxidizing the solid platinum group element under hydrochloric acid acidity to form a chloride complex.

(B) Alkali melting treatment The selenium tellurium platinum group element-containing material, for example, the selenium soot or selenium distillation residue is subjected to an alkali melting treatment. In this alkali melting, a flux composed of a mixture of caustic soda (NaOH) and sodium nitrate (NaNO ₃ ) is added to selenium soot or selenium distillation residue, and this is heated to a melting temperature (eutectic temperature) or higher of the flux to melt. Can be done. By this heating and melting, selenium mainly becomes tetravalent, soda selenite (Na ₂ SeO ₃ ) is generated and dissolved. A mixture of caustic soda and sodium nitrate is used as a flux. When caustic soda is used alone, oxygen supply from the atmosphere is insufficient and sodium selenide (Na ₂ Se) is produced. Since it is converted to metal and deposited, the platinum group and selenium cannot be physically separated. Moreover, it is not preferable to use sodium nitrate alone because the oxidizing power becomes too strong and the ratio of hexavalent selenium increases.

In order to lower the melting temperature, the flux composition is preferably near the eutectic composition. Specifically, it is preferable that caustic soda: sodium nitrate = 75: 25 to 85:15 (molar ratio). Further, the heating temperature is equal to or higher than the eutectic temperature (258 ° C.) of the flux, and since the flux has sufficient fluidity to leach selenide, the heating temperature is preferably 350 ° C. to 450 ° C. Note that sodium nitrate (NaNO ₃ ) generates oxygen within this temperature range, and thus NOx is difficult to generate. However, if the temperature is higher than this temperature range, the rate of NOx generation is high and the oxidizing power is strong, so hexavalent. Since the ratio of selenium becomes large, it is not preferable.

  After the alkali melting, the melt is leached with water and solid-liquid separated. Since sodium selenite dissolves in water, while platinum group elements remain in the residue, the above melt is leached and filtered to obtain a filtrate containing sodium selenite and a residue containing platinum group elements. Can be separated. This filtrate is substantially free of platinum group elements and has good separability between selenium and platinum group elements. Also, platinum group elements contained in the residue are eluted by adding hydrochloric acid to the residue together with an oxidizing agent such as hydrogen peroxide. This can be filtered to recover the filtrate containing the platinum group element. Note that tellurium dissolves in the same manner as selenium in the above-described alkali melting, so that tellurium can be separated from the platinum group by leaching with water.

  Thus, in the alkali melting step, selenium or tellurium dissolves in the water leachate in the form of sodium selenite and sodium tellurite, and is separated from the leach residue containing the platinum group element, but the separated water leachate contains selenium. Since some platinum group elements may remain in addition to tellurium, it may be circulated through the alkali leaching step to perform alkali leaching together with the selenium tellurium platinum group-containing material. This circulation process concentrates the selenium tellurium.

Platinum group dissolution process Add oxidizers such as hydrogen peroxide with hydrochloric acid to the leaching residue containing platinum group obtained in the alkali leaching step and alkali melting step, and elute platinum group elements such as platinum, palladium, rhodium and ruthenium. Let The platinum group element is oxidized by hydrogen peroxide and becomes a chloride complex by chlorine ions, and is stabilized and eluted in the liquid. By this chloride leaching treatment (chlorination), a hydrochloric acid solution in which platinum, palladium, rhodium, ruthenium and the like are dissolved can be obtained.

Gold reduction precipitation step Gold derived from the starting material is slightly dissolved in the platinum group-containing solution. Therefore, hydroxylamine hydrochloride is added to the platinum group-containing solution to selectively reduce and deposit gold. If hydroxyamine hydrochloride is used as the reducing agent, gold can be selectively reduced and deposited even if the platinum group solution is acidic with hydrochloric acid. The added amount of hydroxyamine hydrochloride is suitably 1.3 to 1.6 times equivalent to gold. If this added amount is less than 1.3 times equivalent, the reduction of gold is insufficient, and if it exceeds 1.7 times equivalent, platinum group elements, particularly palladium, are reduced together with gold, so that gold is selectively recovered. I can't. The reduction temperature is preferably 60 ° C. or higher. If it is less than 60 degreeC, a reduction reaction will become slow and it is not suitable as an industrial process.

  The reduced deposit obtained by the above processing method is thoroughly washed, dried, melted by heating, and cast into various sizes of ingots.

  According to the treatment method of the present invention, the gold remaining in the platinum group-containing solution obtained from the treatment process of the selenium tellurium platinum group-containing material can be efficiently separated and separated. Therefore, the treatment method of the present invention is suitable as a demetalization method for separating and recovering selenium tellurium and the platinum group from the reduced soot obtained by reducing the liquid after gold extraction in the process of recovering the noble metal from the copper electrolytic slime. is there.

  Examples and Comparative Examples of the present invention are shown below. % Is wt% unless otherwise specified.

  Selenium cake obtained by reducing the solution after gold extraction of copper electrolytic slime and further subjecting it to distillation (Se: 65%, Te: 30%, Pd: 5%, Pt: 0.5%, Rh: 0.2%, Ru: 0.4 %) 600 g of caustic soda 651 g and sodium nitrate 345 g were mixed and reacted at 400 ° C. for 2 hours for alkali melting. After cooling, 15 liters of water was added to the mixture, and the mixture was stirred for 1 hour and filtered. Se was leached 97.4% in the filtrate, and Pt and Pd were not detected. Further, the ratio of hexavalent Se in the liquid was 10% or less.

  In Example 1, 10 liters of 5 mol / L sodium hydroxide was added to 1 kg of tellurium soot obtained by further introducing sulfurous acid gas into the liquid from which selenium soot was separated. Dissolved in the liquid, and the liquid became dark purple. This was cooled and then filtered to obtain 65 g of a residue. When this residue was analyzed, platinum group elements of Pd, Pt, Rh, and Ru were confirmed as main components. To this residue, 2 liters of hydrochloric acid and 500 ml of water were added for repulping, and 360 ml of hydrogen peroxide was gradually added while maintaining the liquid temperature at 70 ° C. After adding hydrogen peroxide water, the mixture was cooled and filtered. When this filtrate was analyzed, they were Pd81g / L, Pt7g / L, Rh2.1g / L, Ru2.4g / L, Au3.8g / L. To this solution, 6.1 g of hydroxylamine hydrochloride as a reducing agent was added and reacted at 60 ° C. for 1 hour. When the precious metal element in the liquid after cooling was analyzed, the dissolved amount of Pd, Pt, Rh, Ru was not changed, but the dissolved amount of Au was 0.05 g / L, and Au was selectively reduced. Was confirmed.

Comparative example

  When hydrazine was used as the reducing agent in Example 2, Pd and Pt were also reduced together with Au, and Au could not be separated from the liquid.

Process drawing which shows the outline of the processing method of this invention.

Claims (5)

  The selenium tellurium platinum group-containing material is alkali-treated to separate into a selenium tellurium-containing leachate and a platinum group-containing residue, and hydrochloric acid is added to the platinum group-containing residue in the presence of an oxidizing agent to dissolve the platinum group element, followed by solid-liquid separation. A method for separating gold from a platinum group-containing solution, wherein hydroxylamine hydrochloride is added to the filtered platinum group-containing solution to selectively reduce and deposit gold.   As alkali treatment of the selenium tellurium group-containing material, alkali leaching treatment or alkali melting treatment is performed, and hydrochloric acid is added to the platinum group-containing residue obtained by this alkali treatment in the presence of an oxidizing agent to dissolve the platinum group element, The processing method according to claim 1, wherein hydroxylamine hydrochloride is added to another platinum group-containing solution to selectively reduce and deposit gold.   The selenium tellurium group-containing material is mixed with an alkali solution of 1 mol / L or more and subjected to an alkali leaching treatment for leaching selenium and tellurium at a temperature of 60 ° C. or more. Or a mixture of caustic soda and sodium nitrate to a selenium tellurium platinum group-containing material, heated to a temperature higher than the melting temperature of the mixture to dissolve the selenium tellurium, and selenium tellurium by an alkali melting process for leaching with water. The processing method according to claim 1, wherein the treatment is separated into a leaching solution and a platinum group-containing residue, and the separated platinum group-containing residue is dissolved. After the gold extraction of the noble metal recovery treatment system for copper-free copper electrolysis slime is used as the selenium tellurium platinum group-containing material, sulfurous acid gas is introduced into the resulting liquid for reduction treatment, and the selenium soot previously precipitated is distilled to obtain high purity. The distillation residue from which selenium has been separated is subjected to an alkali melting treatment to separate platinum group-containing residues. On the other hand, sulfur dioxide gas is further introduced into the above-mentioned post liquor, and precipitated tellurium is alkali leached to separate platinum group-containing residues. The treatment method according to claim 1, wherein hydrochloric acid is added to these platinum group-containing residues in the presence of an oxidizing agent for solid-liquid separation, and hydroxylamine hydrochloride is added to the filtrate to selectively reduce and precipitate gold. The manufacturing method of the gold | metal | money which carries out the drying after washing | cleaning and heat-melting the reduction | restoration deposit obtained by the processing method in any one of Claims 1-4, and casting to an ingot.

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