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INVENTION
Patent of the Russian Federation RU2291840
METHOD FOR EXTRACTING THE OSYMY AND RHENIUM FROM RINSE SULFURIC ACID
The name of the inventor: Kasikov Alexander Georgievich (RU); Areshina Natalya Stanislavovna (RU); Petrova Anna Mikhailovna
The name of the patent holder: Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials. I.V. Tananaeva of the Kola Science Center of the Russian Academy of Sciences
Address for correspondence: 184209, Murmansk Region, Apatity, ul. Fersmana, 14, Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials. I.V. Tananaeva Kola Scientific Center of the Russian Academy of Sciences, Patent Department, V.P. Kovalevsky
The effective date of the patent: 2005.03.28
The invention relates to the hydrometallurgy of osmium and rhenium, in particular to methods for utilization of osmium-rhenium-containing sulfuric acid formed in the wet gas scrubbing system of copper and nickel industries, and can be used to extract and concentrate osmium and rhenium from wash sulfuric acid. The method involves treating a solution of wash sulfuric acid with a concentration of 300-700 g / l H 2 SO 4 with sodium hypochlorite or calcium until the oxidation-reduction potential of 800-1000 mV is provided to oxidize the osmium to Os (VIII). Then, extraction of osmium and rhenium is successively carried out, first, osmium is extracted and then rhenium is extracted. Extraction of osmium is carried out using, as an extractant, a diluent based on the ultimate hydrocarbons, in particular kerosene or diesel fuel, at an O: B ratio of 1: 5-25 with the transfer of osmium to the extract and rhenium to raffinate. The Osmium-containing extract is heat-treated at 40-85 ° C, kept and filtered to obtain solid-phase osmium concentrate. Rhenium is extracted from the raffinate by an extractant containing 10-40% tertiary amines at a ratio O: B = 1: 25-100. The result of the invention: increasing the extraction of osmium from wash sulfuric acid to obtain its individual concentrate, while ensuring a high extraction of rhenium into the extract.
DESCRIPTION OF THE INVENTION
The invention relates to the hydrometallurgy of osmium and rhenium, in particular to methods for utilization of osmium-rhenium-containing sulfuric acid formed in the wet gas scrubbing system of copper and nickel industries, and can be used to extract and concentrate osmium and rhenium from wash sulfuric acid.
Wash sulfuric acid, formed in the wet gas cleaning system of copper and nickel industries, concentrates most of the osmium and rhenium contained in the feedstock. Effective extraction and separation of these metals to produce individual concentrates remains a difficult problem to date, which is due to the variety of chemical forms of osmium in technological solutions and its dispersion in different phases during extraction extraction. Conversion of osmium compounds into more extractable forms makes it possible to increase the recovery of osmium, which, however, remains insufficiently high. In addition, as the concentration of sulfuric acid in the solution increases, the degree of extraction extraction of rhenium, in particular tertiary amines, decreases.
A method is known for recovering osmium and rhenium from washing sulfuric acid (see RF patent No. 2057071, IPC 7 C 01 G 47/00, 55/00, 28/00, 1996), according to which the treatment of the solution with gaseous chlorine is carried out until the oxidation- Reduction potential of 900-1200 mV, after which a reducing agent is introduced to reduce the value of the redox potential to 750-820 mV. As the reducing agent, a starting solution of washing sulfuric acid, solutions of formaldehyde, sodium sulfite or iron (II) sulphate can be used. Then, osmium and rhenium are extracted with tertiary amines, in particular a solution of tri-n-octylamine in decane, followed by reextraction with 8% ammonium hydroxide solution. The degree of extraction of osmium in the re-extract is 64%, rhenium - 99%. In addition, together with osmium and rhenium, 32% of arsenic is recovered.
The shortcomings of the known method include a low degree of osmium recovery and the use of gaseous chlorine as an oxidant, which is toxic and unsafe from the point of view of labor protection by the reagent. In addition, the use of chlorine requires an adjustment of the oxidation-reduction potential before extraction to remove excess oxidant. The resulting primary concentrate is collective, as it contains osmium, rhenium and arsenic, which must then be separated to produce individual concentrates.
The method closest to the proposed method for the technical essence and the result achieved is a method for recovering osmium and rhenium from washing sulfuric acid (see RF patent No. 2034785, IPC 7 C 01 G 47/00, 55/00, 1995), which comprises treating the sulfuric acid solution with chlorine-containing A reagent with osmium oxidation, a joint extraction of osmium and rhenium with a 10% solution of trialkylamine in kerosene at O: B = 1: 5 and a contact time of 5 minutes, heat treatment of the extract obtained at 50-80 ° C for 20-30 minutes, Re-extraction of rhenium by an 8% solution of ammonium hydroxide. The Osmium-containing extract is returned to the osmium and rhenium extraction stage and, after repeated (up to 10 times) use in circulation, is withdrawn from the process as an osmium-containing primary concentrate, which is sent for processing to recover the osmium. The extraction rate of osmium in the extract is 72.1%, and rhenium - 96.8%.
The disadvantages of this method include a relatively low degree of extraction of osmium in the extract, as well as the production of an osmium-poor primary concentrate in the form of an organic phase, which makes it difficult to further process it. In addition, the method involves the use of gaseous chlorine, which is toxic and unsafe in terms of labor safety reagent.
The present invention is directed to a solution of the problem of increasing the recovery of osmium from wash sulfuric acid to obtain its individual concentrate while ensuring a high extraction of rhenium into the extract.
The technical result is achieved by the fact that in a process for the recovery of osmium and rhenium from wash sulfuric acid, comprising treating the sulfuric acid solution with a chlorine-containing reagent with osmium oxidation, liquid extraction of osmium and rhenium using tertiary amines and a diluent based on the ultimate hydrocarbons and heat treatment of the extract, Chlorine-containing reagent is conducted until the value of the oxidation-reduction potential of 800-1000 mV is reached with the oxidation of osmium to Os (VIII), extraction of osmium and rhenium is carried out in sequence, first extracting osmium and then rhenium, extraction of osmium is carried out using, as an extractant, a diluent On the basis of saturated hydrocarbons with transfer of osmium to the extract, and rhenium to raffinate, heat treated with osmium-containing extract, which is then maintained and filtered to form a solid phase osmium concentrate, and the rhenium is extracted from the raffinate by an extractant containing 10-40% tertiary amines.
The technical result is achieved by the fact that the sulfuric acid solution has a concentration of 300-700 g / l H 2 SO 4 , and sodium chloride or calcium hypochlorite is used as the chlorine-containing reagent for solution treatment.
The technical result is achieved by the fact that kerosene or diesel fuel is used as the extractant based on the ultimate hydrocarbons, and the osmium extraction is carried out at the O: B ratio of 1: 5-25.
The technical result is also directed to the fact that the heat treatment of the osmium-containing extract is carried out at 40-85 ° C.
Achieving the technical result is facilitated by the fact that before the heat treatment the osmium-containing extract is returned to the extraction stage.
Achieving the technical result is also due to the fact that extraction of rhenium is carried out at a ratio of O: B = 1: 25-100.
Treatment of the sulfuric acid solution with a chlorine-containing reagent, in particular sodium hypochlorite or calcium, before providing a redox potential of 800-1000 mV allows the reduced osmium compounds to be quantitatively converted to Os (VIII), which is one of the most readily extractable forms of osmium. With an oxidation-reduction potential of less than 800 mV, no oxidation of the total osmium contained in the wash sulfuric acid solution is achieved, and with an oxidation-reduction potential of more than 1000 mV, an excess of oxidant appears which, for effective extraction, must be removed by the addition of a reducing agent, which complicates the method .
The use of sodium hypochlorite or calcium as an oxidizing agent will allow to provide a dosed supply of these reagents to maintain the oxidation-reduction potential of 800-1000 mV and to avoid the presence of an excess of oxidizer in the solution, which hinders the subsequent extraction of osmium. In addition, the use of these reagents improves working conditions and makes the process more secure.
Selective extraction of osmium allows us to preliminarily separate it from rhenium and obtain a primary osmium concentrate. Concentration of osmium directly from the wash acid prevents dispersion of this metal in different phases, which usually takes place in processes related to the production of primary collective concentrates of osmium and rhenium and their subsequent separation. This helps to increase the through-extraction of osmium by reducing its losses.
The use of a diluent for extraction of osmium based on saturated hydrocarbons, in particular kerosene or diesel fuel, provides selective extraction of osmium into the extract, and rhenium - into raffinate. Thinner based on saturated hydrocarbons in comparison with other extractants used for the extraction of osmium (VIII), usually chemically pure reagents, is a cheaper, affordable and less toxic reagent. In addition, this extractant has a relatively lower solubility in acids and at the same time provides a sufficiently high degree of recovery of this form of osmium.
The choice of the ratio of the organic and aqueous phases of O: B = 1: 5-25 in the extraction of osmium is due to the need to obtain an osmium-rich extract, and to eliminate the unjustified consumption of the extractant. With a ratio of O: B of less than 1:25, the degree of extraction of osmium from the solution to the extract is significantly reduced, and at a ratio O: B of more than 1: 5, the required degree of osmium concentration is not provided.
The heat treatment of osmium-containing extract at a temperature of 40-85 ° C makes it possible to intensify the process of osmium reduction. The specific temperature at which the heat treatment is carried out is determined by the flash point of the type of diluent used within the declared temperature range. The duration of heat treatment is due to the need to ensure the maximum completeness of osmium reduction and is usually 1-2 hours. After heat treatment, the extract spontaneously cools to room temperature.
Extraction of the extract, along with heat treatment, promotes the conversion of the whole osmium to a solid phase concentrate. Duration of exposure is usually 3-10 hours.
The return of the osmium-containing extract to the extraction stage provides an increase in the concentration of osmium in the extract. The number of cycles of extract return depends on the initial concentration of osmium in the solution, the ratio of O: B during extraction, the required concentration of osmium in the extract, and can be from 1 to 10.
Extraction of rhenium rhenium after extraction from osmium washing acid is carried out by an extractant containing 10-40% tertiary amines, the balance is an inert diluent, for example kerosene. Such a concentration of tertiary amines in the extractant helps to increase the extractant's capacity for rhenium and reduce its consumption, but also to obtain a richer organic phase. When processing sulfuric acid solutions with a concentration of 300-500 g / l H 2 SO 4, using an extractant with a tertiary amine content of 10-20% allows a high degree of rhenium extraction. When processing solutions with a concentration of 500-700 g / l H 2 SO 4, the degree of rhenium extraction is significantly reduced, which requires an increase in the content of tertiary amines in the extractant to 20-40%. Increasing the concentration of tertiary amines more than 40% makes the extractant too viscous, which worsens the delamination of the phases and makes the process less technological.
The choice of the ratio of organic and aqueous phases of O: B = 1: 25-100 in rhenium extraction is due to the use of organic extractants highly concentrated in tertiary amines. The ratio of O: B to more than 1:25 leads to an unjustified consumption of the extractant, since when using mixtures containing more than 10% tertiary amines, a sufficiently high degree of rhenium extraction is provided already at 1:25. Extraction with a ratio of O: B of less than 1: 100 leads to a decrease in the degree of extraction of rhenium from the solution.
The method according to the invention is carried out as follows. In a solution of washing sulfuric acid with a concentration of H 2 SO 4 of 300-700 g / l, sodium or calcium hypochlorite is dosed metered up to provide a redox potential of 800-1000 mV relative to the silver chloride reference electrode. This leads to a quantitative oxidation of the reduced forms of osmium to Os (VIII). In the case of calcium hypochlorite, filtration of the resulting solution is provided. Then selectively extract osmium with kerosene or diesel fuel at a ratio of O: B = 1: 5-25 for 10-15 min with the transfer of osmium to the extract and rhenium to the raffinate. The resulting organic and aqueous phases are separated. The extract concentrated in osmium is subjected to heat treatment at a temperature of 40-85 ° C, which is carried out for 1-2 hours. The extract is then cooled to room temperature, aged for 3-10 hours, and the formed solid-phase osmium concentrate is separated by filtration. An increase in the concentration of osmium in the extract can be achieved by a single or multiple return of the osmium-containing extract to the osmium extraction step.
From the raffinate obtained after separation of the organic and aqueous phases, rhenium is extracted with an extractant containing 10-40% of tertiary amines, the rest is an inert diluent, for example kerosene, at a ratio of O: B = 1: 25-100 for 5-10 min. The rhenium-containing extract is sent for further processing to recover rhenium from it by known methods.
The essence and advantages of the claimed method are explained by the following examples.
Example 1 . A solution of 500 ml washing sulfuric acid containing 700 g / l H 2 SO 4 , 8.6 mg / l Os and 9.7 mg / l Re is treated with sodium hypochlorite solution to provide a redox potential of 1000 mV relative to the silver chloride Reference electrode. Then, extraction of osmium with T-6 kerosene is carried out at a ratio of O: B = 1: 5 for 10 minutes, transferring osmium to the extract, and rhenium to raffinate. The resulting organic and aqueous phases are separated. The extraction rate of osmium in the extract is 91.2%. The extract containing 39.1 mg / l of osmium is heat treated at 40 ° C for 2 hours, cooled to room temperature and held for 3 hours. The resulting solid phase osmium concentrate is separated by filtration. The osmium content in the concentrate is 2.4%.
From the raffinate obtained after separation of the organic and aqueous phases, rhenium is extracted with an extractant containing 30% trialkylamine in kerosene of grade T-6 at a ratio of O: B = 1: 25 for 5 minutes. The rate of extraction of rhenium in the extract is 97.5%. The rhenium-containing extract is sent for further processing to recover rhenium from it by known methods.
Example 2 . The wash sulfuric acid solution of Example 1 is treated with sodium hypochlorite solution to provide a redox potential of 1000 mV relative to the silver chloride reference electrode. Then, selective extraction of osmium with diesel fuel is carried out for summer brands DL with a ratio of O: B = 1: 5 for 10 min with transfer of osmium to the extract and rhenium to raffinate. The resulting organic and aqueous phases are separated. The extraction rate of osmium in the extract is 84.7%. To increase the concentration of osmium in the extract, a second extraction cycle is carried out under the same conditions. The extraction rate of osmium in the second extraction cycle is 82.5%. The resulting extract containing 71.9 mg / L osmium is heat treated at 50 ° C for 2 hours, cooled to room temperature and held for 5 hours. The resulting solid phase osmium concentrate is separated by filtration. The osmium content in the concentrate is 3.4%.
From the raffinate obtained after separation of the organic and aqueous phases, rhenium is extracted with an extractant containing 40% of triiso-octylamine in T-6 kerosene at a ratio O: B = 1: 50 for 5 min. The degree of extraction of rhenium in the extract is 98.7%. The rhenium-containing extract is sent for further processing to recover rhenium from it by known methods.
Example 3 . In a solution of washing sulfuric acid in an amount of 1000 ml containing 450 g / l H 2 SO 4 , 4.4 mg / l Os and 6.0 mg / l Re, calcium hypochlorite is introduced to provide a redox potential of 800 mV relative to the chlorine-silver Reference electrode. After treatment with an oxidizing agent, the solution is filtered. Then, extraction of osmium with diesel fuel is carried out with a special grade of DS at a ratio of O: B = 1: 25 for 15 min with the transfer of osmium to the extract, and rhenium to raffinate. The resulting organic and aqueous phases are separated. The Osmium-containing extract is returned to the osmium extraction step. To increase the concentration of osmium, 5 extractions are carried out in the extract. The extraction rate of osmium in individual extraction cycles ranges from 76.9 to 79.4%. The resulting osmium-containing extract containing 422.5 mg / l of osmium is heat treated at a temperature of 85 ° C for 1 hour, cooled to room temperature and held for 10 hours. The resulting solid phase osmium concentrate is separated by filtration. The osmium content in the concentrate is 5.0%.
From the raffinate obtained after separation of the organic and aqueous phases, rhenium is extracted with an extractant containing 20% of triiso-octylamine in T-6 kerosene at a ratio of O: B = 1: 25 for 10 min. The degree of extraction of rhenium into the organic phase is 99.3%. The rhenium-containing extract is sent for further processing to recover rhenium from it by known methods.
Example 4 . A solution of 1000 ml of washing sulfuric acid containing 300 g / l of H 2 SO 4 , 3.2 mg / L of osmium and 4.7 mg / L of rhenium is treated with a sodium hypochlorite solution to provide a redox potential of 900 mV relative to the silver chloride Reference electrode. Then selective osmium extraction is carried out with kerosene of the lighting mark KO-25 at a ratio of O: B = 1: 10 for 15 min with transfer of osmium to the extract and rhenium to raffinate. The resulting organic and aqueous phases are separated. The Osmium-containing extract is returned to the osmium extraction step. To increase the concentration of osmium in the extract, 10 extraction cycles are carried out. The extraction rate of osmium in individual extraction cycles ranges from 80.2 to 86.4%. The resulting osmium-containing extract containing 258.7 mg / l of osmium is heat treated at 50 ° C for 1 hour, cooled to room temperature and held for 5 hours. The resulting solid phase osmium concentrate is separated by filtration. The osmium content in the concentrate is 3.8%.
From the raffinate obtained after the separation of the organic and aqueous phases, rhenium is extracted with an extractant containing 10% triiso-octylamine in kerosene of the illumination grade KO-25 at a ratio of O: B = 1: 100 for 10 min. The degree of extraction of rhenium into the organic phase is 98.4%. The rhenium-containing extract is sent for further processing to recover rhenium from it by known methods.
It can be seen from the above examples that compared to the prototype, the proposed method allows to increase the extraction rate of osmium from washing sulfuric acid by 5-19% and to obtain its individual solid phase concentrate while providing rhenium extraction from solution to 97-99% extract. The process is safer than known methods, including the use of chlorine gas, and its use contributes to the improvement of working conditions.
CLAIM
1. A process for the recovery of osmium and rhenium from wash sulfuric acid, comprising treating the sulfuric acid solution with a chlorine-containing reagent with osmium oxidation, liquid extraction of osmium and rhenium using tertiary amines and a diluent based on saturated hydrocarbons and heat treatment of the extract, Acid solution with a chlorine-containing reagent is conducted until the value of the oxidation-reduction potential of 800-1000 mV is achieved with the oxidation of osmium to Os (VIII), extraction of osmium and rhenium is carried out successively, first extracting osmium and then rhenium, extraction of osmium is carried out using as an extractant A diluent based on saturated hydrocarbons with transfer of osmium to the extract, and rhenium to raffinate, heat treated with an osmium-containing extract which is then maintained and filtered to form a solid phase osmium concentrate, and the rhenium is extracted from the raffinate by an extractant containing 10-40% tertiary amines.
2. A process according to claim 1, characterized in that the sulfuric acid solution has a concentration of 300-700 g / l H 2 SO 4 , and sodium chloride or calcium hypochlorite is used as the chlorine-containing reagent for treating the solution.
3. A method according to claim 1, characterized in that kerosene or diesel fuel is used as the extractant based on the ultimate hydrocarbons, and the osmium extraction is conducted at an O: B ratio of 1: 5-25.
4. A process according to claim 1, characterized in that the heat treatment of the osmium-containing extract is carried out at 40-85 ° C.
5. A process according to claim 1, characterized in that, prior to heat treatment, the osmium-containing extract is returned to the extraction step.
6. A process according to claim 1, characterized in that the extraction of rhenium is carried out at a ratio O: B = 1: 25-100.
print version
Date of publication 14.03.2007gg
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