KR20000012369A - Method for extracting platinum group metals using low temperature and an oxidizing agent - Google Patents

Abstract

PURPOSE: The method for extracting a noble metal is provided which uses relatively strong oxidizer to keep good efficiency and improve productivity through process abridgement. CONSTITUTION: In the extraction method, some of halogen atom or halogen compounds and an oxidizer to oxidize halogen ions are used. Mix reactants including a noble metal with extracts and input them into a reactor. The above reactants and extracts are reacted in the condition of 60 to 80°C by temperature and 1 to 2 kgf/cm¬2 by pressure respectively. Throughout the reaction a noble metal is extracted.

Description

Process for extracting platinum group metals using low temperature and an oxidizing agent

The present invention relates to a method for extracting precious metals such as gold, silver, platinum, palladium, or rhodium from ore or waste materials, and more particularly, by extracting precious metals using a low temperature low pressure reaction process in the precious metal extraction process, Compared with the conventional high pressure reaction process, the present invention relates to a simpler, better extraction efficiency, and a lower cost precious metal extraction apparatus and method.

Recently, precious metals including platinum group metals (PGM) have been used in various fields such as automobile catalysts, electrode materials, medical materials or chemical processes including petroleum refining processes. The demand is also increasing rapidly. However, since the above-described precious metals have limited reserves, in order to solve the problem that the production cost and unit price are very expensive, a process for recovering precious metals from waste materials such as automobile catalyst parts, refinery parts or electronic products is Research has been actively conducted and there is a need for a method for extracting precious metals from waste materials more efficiently and at lower cost.

As a method for extracting the noble metal, two methods such as a pyrometallurgical method and a hydrometallurgical method are generally used. Fluid metallurgy is a method of dissolving a precious metal from a medium into a solution using a predetermined extraction solution, and obtaining a desired precious metal in solid form in the next refining process. Hot metallurgy applies a high temperature to an ore or waste catalyst. It is a method of extracting precious metals by melting and separating metals and precious metals contained in ore or spent catalyst.

In the noble metal extraction method described above, since the hot metallurgy requires a large amount of energy in order to apply high heat to the ore or the waste catalyst, an expensive treatment cost is required to extract the noble metal using the hot metallurgy method. Therefore, the fluid metallurgy method, which requires relatively low cost, is preferred because the precious metal is extracted using a predetermined extraction solution.

Among the above-described fluid metallurgy methods, cyanide extraction and aqua regia extraction are generally used. The cyan extraction process is a method of extracting gold, silver, and platinum group precious metals into a solution by reacting an ore or waste catalyst containing a precious metal with an aqueous solution made of a compound of genus and cyan (eg, NaCN or KCN). In the case of extracting precious metals using the excellent redox potential of nitric acid with high acidity and the high complexation ability of chlorine ion, and the cyanide extraction process, the toxicity of cyan It is very strong and not only causes environmental pollution, but also slows the reaction rate, so it takes considerable time to extract precious metals. In addition, when using aqua regia process, when processing precious metals with high reactivity such as platinum group metals, they are highly stable. , A significant amount of extraction solution is used to increase the cost, and due to the strong acidity of the aqua regia, The problem of reducing the efficiency of the subsequent extraction step was caused to fuse to be.

Therefore, various precious metal extraction processes have been proposed to solve the problems occurring in the above-described conventional fluid metallurgy, and one of the most effective methods is an extraction method using a halogen compound and a halogen element (I ₂ or Br ₂ ). to be.

As a extraction method using a halogen compound and a halogen element, USP 5,292,490 (Willem PC, Duyvesteyn et al.) "Recovery Platinum Group Metals from Oxides Ores" using bromine (Br ₂ ) and a compound of an alkali metal and bromine, A process for extracting platinum and rhodium has been proposed. Bromine (Br ₂ ) is an oxidizing agent that dissolves noble metals contained in powdered ores or spent catalysts in an ionic state in an extraction solution of pH 1.0 or lower, and bromine ions (Br ⁻ ) produced from alkali-bromine compounds are precious metals. It forms a water-soluble complex with and plays a role of keeping the dissolved precious metal in a stable water-soluble state in the solution. On the other hand, the reaction temperature and time suggested as the optimum conditions in this method is about 70 ℃, about 2 hours, which can reduce environmental pollution and shorten the process time, compared to the conventional cyan extraction method or aqua regia extraction method. The extraction rates of platinum, rhodium and 90%, 85%, and 70% are relatively low, and the extraction potential of palladium, which is useful as a catalyst, is unclear, which makes it difficult to apply commercially. Here, the reason why the extraction efficiency is low is that bromine (Br ₂ ) oxidizes and ionizes the noble metal in the medium and is then reduced to bromine ions (Br ⁻ ), in which the concentration of bromine (Br ₂ ) in the solution is in the process. This is because the ionization rate of the noble metal decreases as the decrease of.

On the other hand, in order to solve the problems of the above-described bromine (Br ₂ ) and the precious metal extraction process using the compound of the alkali metal and bromine, USP 5,620,585 (Ahmad Dadgar et al.) "Inorganic Perbromide Compositions and Methods of Use Thereof" A method of introducing an electric field into an extract solution by oxidizing halogen ions (Br ⁻ ) generated in the ionization process to halogens (Br ₂ ) again. As a result of this method, 4 to 50% of bromine ions were oxidized to bromine, whereby high extraction efficiencies for gold, silver, platinum and palladium were obtained. However, in the case of carrying out a method of applying an electric field by contacting electrodes in the extraction solution during the extraction process, a separate device such as a power generating device and an electrode must be added in addition to the reaction device, which complicates the configuration of the device and increases the manufacturing cost. In addition, there is a problem in that the process is complicated.

Meanwhile, in US Pat. No. 5,328,669 (Kenneth N, Han et al.) "Extraction of Precious Metals from Ores and Other Precious Metal Containing Materials Using Halogen Salts, compounds of halogen, alkali metals and halogens (e.g., Property of potassium halide, potassium iodide, sodium bromide, sodium iodide, etc. A process for extracting precious metals from powdery ores or waste materials by injecting oxygen (O ₂ ) as an agent has been proposed, wherein ammonium ions in the extraction solution serve as a catalyst for promoting the oxidation reaction. According to the technique, since the pH of the extraction solution used is relatively high, about 3-10, extraction by dissolution of the medium Can solve the contamination problem of the fluid, gold, silver, and 90 regardless of the extraction medium, such as platinum, palladium and rhodium were excellent degree of 98%.

However, the above-described conventional precious metal extraction method has the following problems.

First, after promoting yonghaeeul of precious metals and the ionization of the noble metal reducing a halogen ion (I ^- or Br ^-) to the case re-oxidation using an oxygen (O ₂₎ as a property agent to, oxygen and halogen ions are reacted at a high temperature In this case, in order to facilitate the reaction, the extraction process must be performed under conditions of 150 to 200 ° C. and 10 Kgf / cm 2 or more, respectively, in the autoclave. .

Secondly, in order to withstand the strong oxidative properties of the halogen gas reacting with oxygen, it is necessary to manufacture a high pressure reactor with an expensive acid resistant metal, and thus, there is a problem in that the production of a noble metal extraction device requires a considerable cost.

Therefore, an object of the present invention is to solve the problems of the existing process and at the same time to provide a high extraction efficiency and economical precious metal extraction process.

In order to achieve the above object, according to one aspect of the present invention, the noble metal extraction method of the present invention, using a halogen element or a portion of a halogen compound or a mixture thereof, to a noble metal extraction method using an oxidizing agent for oxidizing halogen ions In the step, the reaction mixture containing the noble metal with the extraction solution is added to the reaction tank, and the reaction and the extraction solution in the reaction conditions of the temperature and pressure in the reaction tank of 60-80 ℃ and 1-2 Kgf / cm2, respectively And extracting the noble metal using a refining process after the reaction.

In addition, according to another aspect of the present invention, the noble metal extraction method of the present invention is an oxidizing agent for oxidizing the reduced halogen ions after ionizing the noble metal, ozone (O ₃ ), NOx compounds, copper ions, cobalt Preference is given to using one or a mixture of ions, manganese ions, hydrogen peroxide, sodium hypochlorite.

In general, in order to effectively extract noble metals from ore or spent catalyst, halogen ions (I ₂ or Br ₂ ) serving as oxidants for oxidizing and dissolving noble metals present in the medium in an ionic state, and dissolved noble metal ions and water-soluble stable Halogen ions (I ⁻ or Br ⁻ ) must be present to form the complex, and a second oxidant must be continuously supplied to oxidize the reduced halogen element after oxidizing the precious metal. As the second oxidant, oxygen is most widely used, but as described above, when oxygen is used as the second oxidant, the oxidizing power of oxygen is relatively weak, requiring reaction conditions at high temperature and high pressure.

Therefore, in the present invention, by using a material having better oxidizing power than oxygen as the second oxidant, halogen element is effectively reoxidized even under the reaction conditions of low temperature and low pressure, and thus, a more economical and efficient precious metal extraction process is disclosed.

Hereinafter, the low temperature low pressure precious metal extraction method according to the present invention will be described in detail.

First, in order to facilitate the contact of the waste materials or minerals containing the precious metal with the extraction solution, the waste materials or minerals are pulverized into powder form. At this time, the size of the powder is preferably, for example, 100 mesh or less.

Next, the powdered mineral containing the noble metal is mixed in a leaching solution. Here, the extraction solution, the extraction solution, bromine (Br ₂ ), iodine (I ₂ ) or a mixture of halogen or potassium bromide (KBr), sodium bromide (NaBr), potassium iodide (KI), sodium iodide ( NaI) or an aqueous solution of a halogen salt of alkali metal or a mixture of these (halogen element and halogen salt of alkali metal) which is a mixture of some of them, the concentration of each of which is preferably about 0.001-3 mol / L. At this time, when treating ore and waste catalyst containing rhodium (Rh), it is preferable to use sulfuric acid as an extraction solution.

Next, the mineral in the form of powder containing the noble metal and the latching solution are added to the reactor in the form of a slurry. When the slurry is introduced into the reactor, the slurry in the reactor is maintained at an appropriate temperature and pressure condition, and the slurry is stirred to dissolve the precious metal in the ionic state from the mineral in powder form.

In the reaction process, the halogen element included in the leaching solution ionizes itself while ionizing the precious metal element included in the mineral. Since these ionized halogen ions (Br ⁻ , I ⁻ ) cannot be used again for noble metal ionization, in the present invention, in order to oxidize the halogen ions to halogen elements, ozone (O) is used as an oxidizing agent of halogen ions reduced after noble metal ionization. ₃ ) strong NOx-based compounds, cupric ions, cobalt ions, cobaltic ions, manganic ions, hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO ₂ ) Inject the substance with. At this time, it is preferable that the amount of the oxidizing agent added is about 0.01-1 mol / L based on the volume of the extraction solution.

In addition, as a catalyst for promoting oxidation of halogen ions to halogen elements, ammonium ions can be added to the extraction solution, and as a source thereof, ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium carbonate or mixtures thereof can be used. have. At this time, it is advantageous that the concentration of ammonium ions introduced into the extraction solution is about 0.001-3 mol / L.

Here, in the case of using the above-mentioned substances having strong oxidizing power such as ozone (O ₃ ), NO x compounds, copper ions, cobalt ions, manganese ions, hydrogen peroxide, sodium hypochlorite or a mixture thereof as an oxidizing agent in the extraction reaction In the reaction tank, the temperature and pressure can be reacted under the reaction conditions of 60-80 ° C. and 1-2 Kgf / cm 2, respectively. At this time, the reaction time takes about 1 hour to 2 hours.

Among the oxidants described above, when a solid or liquid oxidant is used, a necessary amount may be added during the preparation of the extraction solution or a predetermined amount may be injected into the reaction solution during the reaction, and when using a gaseous oxidant, an extraction reaction occurs. It is preferable to inject into the extraction solution at a constant rate. In this case, in order to maximize the efficiency of the oxidizing agent added, it is also possible to further inject oxygen into the reaction solution.

In addition, when using the excellent oxidizing power of the NOx compound produced during the production of aqua regia or nitric acid / ethanol, using a bubble generated by administering aqua regia or nitric acid / ethanol mixture directly to the extraction solution in the reaction tank, or aqua regia Alternatively, only the gas generated in preparing the mixture of nitric acid / ethanol can be injected into the extraction solution in the reaction tank. At this time, the mixing ratio of nitric acid / ethanol mixture is preferably about 1: 0.5 -1: 2 by volume.

Here, when the amount of aqua regia or nitric acid / ethanol mixture is directly administered to the extraction solution, 5-30% and 5-20% of the volume of the extraction solution are appropriate, respectively, and a predetermined amount is added at regular intervals during the reaction. It is preferable.

In addition, when only gas generated during mixing is used, the gas generated when preparing 20-40% and 10-30% of the volume of the extraction solution for the aqua regia or nitric acid / ethanol mixture is injected into the extraction solution in the reactor. When producing gas, the temperature of aqua regia or nitric acid / ethanol mixture should be about 60-90 ℃. In order to maximize the effect of oxidizing agent during the reaction, the extraction solution is brought into contact with the atmosphere or additional oxygen is injected into the reaction solution. It is also possible.

Finally, the noble metal is extracted by refining the ionized noble metal contained in the slurry, and a well-known solvent extraction method, ion exchange method or adsorption method may be used as the method.

Hereinafter, preferred embodiments of the present invention will be described.

As waste materials or minerals containing precious metals used in the present invention below, the waste materials used as automotive catalysts are ground to form powders of 100 mesh or less. Here, the powdered raw material has a mass of 100 g, and the content of the noble metals included is shown in Table 1.

Example 1

a. Extraction solution: Dissolve 0.02 mol (5 g), 0.33 mol (50 g) and 0.2 mol (10.7 g) of iodine (I ₂ ), sodium iodide (NaI) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water Prepared by adjusting the pH to 1.0

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Input oxidant and input amount: Ozone (O3) is injected into the mixture of extractant and waste catalyst powder at a rate of 90 mL / min (0.48 mol / L) during the reaction.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 98%, 96% and 96%, respectively.

Example 2

a. Extraction solution: Dissolve 0.03 mol (4.8 g), 0.4 mol (48 g) and 0.2 mol (10.7 g) in bromine (Br ₂ ), potassium bromide (KBr) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water. Prepared by dosing to adjust pH to 1.0.

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Input oxidizer and input amount: 15ml of aqua regia is added to the mixture of extract solution and powder every 10 minutes (18% of the total volume of extract solution) during the reaction, and pure oxygen is added to the extract solution at 100mL / min while stirring.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by Induction Coupled Pl-Atomic Emission Spectroscopy (ICP-AES) to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were respectively Very good at 98%, 97% and 97%.

Example 3

a. Extraction solution: Dissolve 0.03mol (4.8g), 0.4mol (48g) and 0.2mol (10.7g) in bromine (Br ₂ ), potassium bromide (KBr) and ammonium chloride (NH4Cl) in 1000mL of distilled water, respectively. Prepared by dosing to adjust pH to 1.0.

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Input oxidant and input amount: Initially, 60 ml of nitric acid was initially added to the extraction solution, and then ethanol was added to the mixture of the extraction solution and the waste catalyst powder every 12 minutes for 6 ml (12% injection volume of extraction solution, nitric acid: Volume ratio of ethanol is 1: 1.2) and pure oxygen was added to the extraction solution at 100 mL / min while stirring.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 99%, 93% and 95%, respectively.

Example 4

a. Extraction solution: Dissolve 0.02 mol (5 g), 0.33 mol (50 g) and 0.2 mol (10.7 g) of iodine (I ₂ ), sodium iodide (NaI) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water Prepared by adjusting the pH to 1.0

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Input oxidant and input amount: Inject gas generated from 300ml of aqua regia (30% of the volume of extraction solution) prepared at the same temperature during the reaction into the mixture of extraction solution and waste catalyst powder. And injected into the extraction solution at 100 mL / min.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 98%, 91% and 90%, respectively.

Example 5

a. Extraction solution: Dissolve 0.02 mol (5 g), 0.33 mol (50 g) and 0.2 mol (10.7 g) of iodine (I ₂ ), sodium iodide (NaI) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water Prepared by adjusting the pH to 1.0

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Input oxidant and input amount: Inject the gas generated by adding 6 ml of ethanol to 125 ml of nitric acid every 10 minutes at the same temperature during the reaction into the mixture of extraction solution and waste catalyst powder (25% of the extraction solution volume, nitric acid) : Ethanol volume ratio is 1: 0.58) and pure oxygen is added to the extraction solution at 100 mL / min while stirring.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 98%, 91% and 89%, respectively.

Example 6

a. Extraction solution: Dissolve 0.02 mol (5 g), 0.33 mol (50 g) and 0.2 mol (10.7 g) in iodine (I ₂ ), sodium iodide (NaI) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water Prepared by adjusting the pH to 1.0

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Charged oxidizer and dose: Inject hydrogen hydrogen peroxide (H ₂ O ₂ ) into the mixture of extraction solution and waste catalyst powder every 10 minutes (0.7mol / L).

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 98%, 93% and 94%, respectively.

Example 7

a. Extraction solution: Dissolve 0.03 mol (4.8 g), 0.4 mol (48 g) and 0.2 mol (10.7 g) in bromine (Br ₂ ), potassium bromide (KBr) and ammonium chloride (NH 4 Cl) in 1000 mL of distilled water. Prepared by dosing to adjust pH to 1.0.

b. Temperature and pressure conditions of the reactor: 70 ℃, 1 atmosphere.

c. Reaction time: stirring for 2 hours

d. Charged oxidizer and amount charged: 15g (0.24mol / L) of copper ions were added to the mixture of the extraction solution and the waste catalyst powder before the reaction, and pure oxygen was added into the extraction solution at 100mL / min while stirring.

After completion of the reaction, the mixture was filtered and the amount of precious metal present in the filtrate was measured by ICP-AES to calculate the extraction rate. The extraction rates of platinum, palladium and rhodium were very good at 98%, 95% and 94%, respectively.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above specific embodiment, and it is clear that the same result can be obtained even by a combination of conditions other than those described in the above embodiment.

As described above, in the noble metal extraction method according to the present invention, in the noble metal extraction method using a halogen salt or a mixture thereof and an ammonium salt of a halogen element or an alkali metal, as an oxidizing agent of halogen ions reduced after ionization of the noble metal, Injecting a highly oxidizing substance during the reaction allows the reaction to be carried out even under relatively low temperature and low pressure conditions while maintaining excellent extraction efficiency. Since the high pressure condition becomes unnecessary, productivity is improved by the process simplification, and cost reduction by the simplification of a device is attained.

Claims (18)

In a noble metal extraction method using a halogen element or a part of a halogen compound or a mixture thereof, and using an oxidant for oxidizing halogen ions: Mixing a reactant containing a noble metal with an extraction solution and introducing the same into a reaction tank; Reacting the reactant and the extraction solution at a reaction temperature of 60 to 80 ° C. and 1 to 2 Kgf / cm 2, respectively, at a temperature and a pressure in the reactor; And Precious metal extraction method comprising the step of extracting the noble metal using a refining process after the reaction. The oxidizing agent according to claim 1, wherein the noble metal is ionized to oxidize a reduced halogen ion, and one or more of ozone, a NOx compound, copper ion, cobalt ion, manganese ion, hydrogen peroxide, sodium hypochlorite Precious metal extraction method characterized by using a mixture. The method of extracting noble metals according to claim 2, wherein the amount of the oxidizing agent is 0.01 to 1 mol / l based on the volume of the extraction solution. The method of claim 2, wherein when the oxidant is added in a solid or liquid state, a predetermined amount is added during preparation of the extraction solution or a predetermined amount is divided in the course of the reaction. Precious metal extraction method, characterized in that. The oxidizing agent for oxidizing a reduced halogen element after ionizing the noble metal, and when using a NOx-based compound, the NOx-based compound is a gas generated when preparing aqua regia or a mixture of nitric acid / ethane holes. Precious metal extraction method, characterized in that using. 6. The method of claim 5, wherein the mixing ratio of the nitric acid / ethane hole mixture is 1: 0.5 to 1: 2 on a volume basis. 6. The method according to claim 5, wherein when the aqua regia or nitric acid / ethanol mixture is directly added to the extraction solution, the amounts of aqua regia or nitric acid / ethanol mixture are 5-30% and 5-20% of the volume of the extract solution, respectively. Characterized in the precious metal extraction method. 7. The method of extracting precious metals according to claim 6, wherein the mixture of aqua regia or nitric acid / ethanol is added at a predetermined time interval. 6. The method according to claim 5, wherein when injecting only the gas generated during the mixing of the aqua regia or nitric acid / ethanol, the amount of gas injected is 20-40% and 10% of the volume of the extract solution for the aqua regia or nitric acid / ethanol mixture, respectively. Precious metal extraction method, characterized in that the injection of gas generated when manufacturing 30%. 10. The method of claim 9, wherein the temperature of the aqua regia or nitric acid / ethanol mixture is 60-90 ℃. The method of extracting noble metals according to claim 2, wherein oxygen is additionally injected when the oxidant is injected. The method of claim 1, wherein the extraction solution is a bromine, iodine or a mixture of a halogen element, potassium bromide, sodium bromide, potassium iodide, sodium iodide or a mixture of some of them, a halogen salt of an alkali metal, or a mixture thereof Precious metal extraction method, characterized in that the aqueous solution. 13. The method of extracting precious metals according to claim 12, wherein the concentrations of the extract solution are about 0.001-3 mol / L, respectively. 13. The method of extracting noble metals according to claim 12, wherein the extraction solution contains sulfuric acid when the reactant is an ore containing rhodium. The method of extracting noble metals according to claim 2, wherein ammonium ions are further added to the extraction solution as a catalyst for promoting oxidation of the halogen ions to halogen elements. 16. The method of extracting precious metals according to claim 15, wherein ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium carbonate or a mixture thereof is used as the source of ammonium ion. The method of claim 15, wherein the concentration of the ammonium ion is precious metal extraction method, characterized in that 0.001 to 3 mol / L. The method of claim 1, wherein the mineral containing the noble metal is ground to less than 100 mesh and mixed with the extraction solution in the form of powder precious metals.