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INVENTION
Patent of the Russian Federation RU2044084
METHOD OF PROCESSING OXIDE-CONTAINING PRODUCTS
The name of the inventor: Greiver TN; Cassacière EL; Vergizova TV; Khudyakov VM; Haydov VV; Lomonosov VN; Kulakova AA
The name of the patent holder: Severonikel Combine of the Russian State Concern for the Production of Non-Ferrous and Precious Metals "Norilsk Nickel"
Address for correspondence:
Date of commencement of the patent: 1993.06.15
The invention relates to hydrometallurgy and can be used in the production of osmium. Essence: the method involves distilling osmium tetroxide from a pulp consisting of dilute sulfuric acid and osmium-containing products using an oxidizer providing an oxidation-reduction potential (ORP) of 1 to 1.2 V, absorption of osmium tetroxide by KOH solution. Precipitation of potassium osmate is made by reducing the ORP to 0.2 0.25 V by introducing a reducing agent. The precipitate is separated by filtration, after which the mother liquor is returned to the absorption of osmium tetroxide. The invention makes it possible to simplify and close the technological cycle.
DESCRIPTION OF THE INVENTION
The invention relates to hydrometallurgy and can be used in the production of osmium.
A method for the processing of osmium-containing products, for example osmium iridium, is known which includes fusing with sodium peroxide or a mixture of sodium or potassium nitrate with alkali, loading the melt into the distillation apparatus, introducing an oxidizing mixture of concentrated nitric and hydrochloric acids, and distilling osmium tetroxide while heating and sucking the purified air [ 12]
Sulphurous osmium, isolated from waste solutions, was directly introduced into the distillation apparatus, and osmium was distilled in the form of tetroxide from the serum-drinking medium. Direct distillation of osmium from 2% osmium concentrates is provided at Port-Colborn (Canada) using KClO 3 . These oxidants provide a joint distillation of osmium and ruthenium, which are captured by alkaline solutions. From the solutions, ruthenium is precipitated in the form of dioxide with an alcohol or thiosulfate, and after separation of the precipitate, osmium is isolated with ammonium chloride in the form of a Frémy salt.
A common feature of this technology with the claimed method is the distillation of osmium into the gas phase in the form of osmium tetroxide with trapping it with an alkaline solution.
A significant disadvantage of this analogue is that it does not ensure selective distillation of osmium, which is carried out together with ruthenium. This leads to the need to purify the solution from ruthenium. The isolation of osmium in the form of a Frémy salt with the help of ammonium chloride does not precipitate osmium quantitatively and additional osmium pre-precipitation operations are required. Accumulation of reagents excludes the possibility of circulation of solutions, which are subject to neutralization and discharge.
Methods are known for the separation of osmium and ruthenium in the osmium tetroxide stripping phase, for example, selective distillation of osmium tetroxide by hydrogen peroxide in analytical practice. However, distillation of osmium tetroxide with hydrogen peroxide requires preliminary conversion to a solution of osmium iridium or other concentrates, for example, by fusion with sodium peroxide or a mixture of sodium or potassium nitrate with alkali and leaching of melt.
The method closest to the invention is a process for the processing of osmium-containing concentrates, which comprises distilling osmium tetroxide from the pulp in dilute sulfuric acid solution with an oxidizer, absorbing by absorption of osmium tetroxide with an alkaline solution, and precipitating potassium osmate with a reducing agent.
The disadvantages of the prototype are:
An oxidizer is used which does not ensure the selective distillation of osmium, which is distilled together with ruthenium, which requires additional operations for their separation;
When the osmium tetroxide is absorbed, a solution of NaOH is used, followed by the KOH solution, which eliminates the turnover of solutions and requires additional operations to extract the osmium.
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FIGS. 1 and 2 show, respectively, a comparison of the prototype process schematics and the proposed method.
The aim of the invention is to simplify the technology, increase recovery of osmium and reduce the consumption of reagents by providing selectivity in the distillation of osmium and the possibility of working in a closed loop.
According to the invention, in a method for processing osmium-containing products comprising distilling osmium tetroxide with an oxidizer from a pulp consisting of dilute sulfuric acid and osmium-containing products, absorbing osmium tetroxide with an alkaline solution and precipitating potassium osmate with a reducing agent, distillation is carried out with an oxidizer providing the oxidation-reduction potential of the pulp (ORP) from 1 V to 1.2 V, the absorption is carried out by KOH solution, and the precipitation of potassium osmate is carried out by a soft reducing agent, after which the mother liquor is returned to the absorption of osmium tetroxide.
When the ORP value is below 1.0 V, the impurities contained in the concentrate are suspended: sulfur and selenium suspensions, and only then osmium begins to distill off. Partial volatilization of osmium may accompany the oxidation of selenium. Ruthenium is easily oxidized with the formation of ruthenyl sulfate and passes into solution, but the formation of volatile ruthenium tetroxide with a pulp potential of less than 1.2 V does not occur.
The ORP value above 1.2 V leads to the volatilization of ruthenium tetroxide and a violation of the selectivity of osmium distillation.
In addition, the pulp is heated at least 90 ° C, after which the oxidant is introduced gradually until the oxidation-reduction potential is reached below 1 V. As an oxidizer, alkali metal persulphates can be used. Capture of potassium osmate can be achieved by a KOH solution with a concentration of 300-600 g / l. As a reducing agent, ethanol or methanol can be used. The absorption of osmium tetroxide is carried out with a circulating solution of KOH containing the reducing agent.
When the invention is used, conditions are created under which selective osmium distillation takes place in the form of its tetroxide and a technologically simple precipitation of potassium osmate.
The method is implemented as follows. The starting osmium concentrate is loaded into the reactor, it is poured with a sulfuric acid solution of 50-200 g / m3 at G: T (2-4): 1, the mass is heated to 90-100 ° C, and the oxidant gradually introduced into the reactor, the amount of which is controlled by the change ORP. Distillation is carried out with vigorous stirring with air sucking through the solution. The duration of distillation is determined by the time to reach the ORP value of 1-1.2 V. The exhaust gases enter the sump system consisting of a spray catcher, three osmium absorbers filled with a reverse solution of potassium hydroxide with a concentration of 450 g / dm 3 .
The solution from the first absorber comes to be reconstituted with a solution of ethyl alcohol. The end of the recovery is determined by the color change from dark magenta to violet and fall of ORP to 0.2-0.25 V. A violet precipitate of potassium dioxo tetrahydroxoosmate is formed, the pulp is filtered, the spent alkaline solution is returned to the absorption of osmium.
The invention makes it possible to simplify the technology of processing osmium-containing products, to increase the extraction of osmium from concentrates, to reduce the consumption of reagents and to ensure the possibility of working in a closed loop, thereby eliminating harmful discharges into the environment.
CLAIM
1. A METHOD FOR PROCESSING OXYMIC CONTAINING PRODUCTS, including osmium distillation upon introduction of an oxidant from a pulp containing dilute sulfuric acid and osmium-containing products, absorption of osmium tetroxide with an alkaline solution, and precipitation of potassium osmate by a reducing agent, characterized in that the distillation is carried out by gradually introducing an oxidizing agent to achieve redox The absorption is carried out with a solution of potassium hydroxide, and the precipitation of potassium osmate is carried out by reducing the oxidation-reduction potential to 0.2-0.25 V by introducing a reducing agent, the precipitate is separated by filtration, and the mother liquor is then returned to the absorption of tetraoxide Osmium.
2. A method according to claim 1, characterized in that the pulp is heated to a temperature of at least 90 ° C., after which the oxidant is introduced gradually until the oxidation-reduction potential is at least 1 V.
3. A process according to claim 1, characterized in that alkaline persulfates are used as an oxidizing agent.
4. A method according to claim 1, characterized in that the absorption is carried out with a solution of potassium hydroxide at a concentration of 400-600 g / l.
5. A process according to claim 1, characterized in that ethanol is used as the reducing agent.
6. A process according to claim 1, characterized in that methanol is used as the reducing agent.
7. A method according to claim 1, characterized in that the absorption of osmium tetroxide is carried out with a reverse caustic potassium solution containing the reducing agent.
print version
Date of publication 14.03.2007gg
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