Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G29/00—Compounds of bismuth
  • C01G29/003—Preparations involving a liquid-liquid extraction, an adsorption or an ion-exchange
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G28/00—Compounds of arsenic
  • C01G28/001—Preparation involving a solvent-solvent extraction, an adsorption or an ion-exchange
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G30/00—Compounds of antimony
  • C01G30/001—Preparation involving a solvent-solvent extraction, an adsorption or an ion-exchange
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G49/00—Compounds of iron
  • C01G49/0009—Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/28—Amines
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/32—Carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/32—Carboxylic acids
  • C22B3/322—Oxalic acids
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
  • C22B3/38—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds containing phosphorus
  • C22B3/386—Polyphosphoric oxyacids, or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the invention relates to an improved method for the separation of interfering elements, selected from arsenic, antimony, bismuth and / or iron, from valuable metal electrolyte solutions by extraction from the liquid phase and subsequent extraction of the interfering elements for recycling.
• valuable metals are understood to mean those metallic elements which are obtained from their natural sources, in particular from their ores, by industrial processes and are used in metallic form, optionally in alloy with other metals Find.
• hydrometallurgical processes also play an important role in the extraction of valuable metals.
• the metals or metal salts contained in the ores are digested or leached with aqueous systems and the valuable metal is obtained from such metal salt solutions by electrolysis.
• the efficiency of the electrolysis of such aqueous solutions is severely impaired by the fact that most valuable metals in ores are "associated" with other metals.
• the electrolyte solutions for the recovery of valuable metal therefore almost always contain more or less large amounts of interfering elements which impair the electrolytic recovery of the valuable metal or are deposited together with the valuable metal as disruptive impurities.
• To the purity of the electroly To increase valuable metals deposited on the table, it is therefore desirable to remove as many interfering elements as possible from valuable metal electrolyte solutions.
• the metals copper, zinc, cobalt or nickel can be obtained electrolytically.
• aqueous solutions from the leaching of ores containing these metals usually contain more or less large amounts of interfering elements. Satisfactory processes for the separation and, if necessary, also recovery of such interference elements are sought not only because the quality and quantity of the deposited valuable metals can be improved, but also because the extraction and recycling of the interference elements is economically and ecologically sensible.
• the extraction of high-purity copper by pyrometallurgical refining is characterized, for example, by two separate process steps.
• the melting metallurgical refining relatively impure raw copper originating from the smelting of copper ores is separated from the melt ("anode furnace"). Copper "(up to 99.99% Cu) is deposited on the cathode.
• the cathode blocks made of high-purity copper can then be further processed by plastic deformation (rolling, drawing, pressing, etc.).
• DE-OS 26 03 874 describes a process for removing arsenic from the copper refining electrolytes in which the aqueous electrolyte solution is brought into contact with an organic phase containing tributyl phosphate and the arsenic contained in the solution is thereby extracted into the organic phase .
• an organic solution containing tributyl phosphate in admixture with quaternary ammonium compounds is also used as the extractant.
• Tributyl phosphate and organic esters of phosphonic acid, phosphonous acid, phosphinic acid and phosphinous acid are used in processes according to DE-OS 26 14 341 and 26 15 638 together with organic solvents as extractants in order to separate arsenic or antimony from copper electrolyte solutions.
• Arsenic is also separated from copper refining electrolytes in a process according to EP-A-0 106 118 using organophosphorus compounds, for example trioctylphosphine oxide (TOPO), in organic solvents such as kerosene.
• TOPO trioctylphosphine oxide
• DE-OS 34 23 713 discloses a further process for removing arsenic from sulfuric copper electrolytes, in which aliphatic alcohols having 6 to 13 carbon atoms, preferably 2-ethyl-1-hexanol, are used in the organic phase as extractants become. Most, if not all, of the arsenic can be removed from the electrolyte solution over six extraction cycles.
• organophosphorus extractants in particular TBP
• TBP organophosphorus extractants
• a so-called modifier usually iscdecanol, must be added to the extractant in all of the processes mentioned to improve the separation of the organic from the inorganic phase, which, under certain circumstances, can still accelerate the decomposition of the extractant.
• German patent application P 37 25 611.4 This relates to a process for the joint separation of arsenic, antimony, bismuth and iron side by side from valuable metal electrolyte solutions by means of solvent extraction and subsequent recovery of the said interfering elements, which is characterized in that aqueous, mineral acidic valuable metal electrolyte solutions with a slightly water-soluble added organic solvent, which contains one or more hydroxamic acid (s), mixes the two phases intensively, the interfering elements arsenic, antimony and bismuth precipitate out of the organic phase by sulfide precipitation, the sulfides are separated off and the iron still remaining in the organ phase is subsequently removed with a water-soluble complexing agent for iron re-extracted into an aqueous phase and recovered.
• aqueous, mineral acidic valuable metal electrolyte solutions with a slightly water-soluble added organic solvent, which contains one or more hydroxamic acid (s) mixes the two phases intensively, the interfering elements arsenic, antimony and
• the interference elements are re-extracted by sulfide precipitation from the loaded organophase, the interference metals being obtained as sulfide filter cakes.
• This filter cake usually consists of the components arsenic sulfide, antimony sulfide and bismuth sulfide As is known, it must first be laboriously separated and worked up for further economic use.
• the object of the present invention is, in view of the described prior art, to provide a method for the removal of interfering elements from valuable metal electrolyte solutions and the subsequent extraction of these interfering elements for further use, which involves the separation of the four interfering elements arsenic (As), antimony (Sb ), Bismuth (Bi) and / or iron (Fe), but in particular enables the main constituent arsenic to be separated off, using smaller amounts of the precipitant hydrogen sulfide.
• the process measures according to the invention can be used to selectively separate out some of the interfering element ions, and in the case of the arsenic ion even selectively generate As (III) ions or As (V) ions.
• this selective interference element separation allows the interference element ions to precipitate out in an easily processable form.
• R can represent alkyl, cycloalkyl or aryl radicals having 7 to 44 carbon atoms, preferably so-called “neo-alkyl radicals” which contain a quaternary carbon atom adjacent to the carbonyl group.
• "J. Chem. Research” (S) 1982, 90 ff also describes the solvent extraction of transition metals with so-called versato-hydroxamic acids of the general formula (B), in which the radicals R are branched and contain 10 to 15 carbon atoms Are alkyl residues.
• the invention relates to a process for the separation of elements selected from arsenic, antimony, bismuth and / or iron, from valuable metal electrolyte solutions by means of solvent extraction and subsequent recovery of said interfering elements, in which aqueous, mineral acid, valuable metal electrolyte solutions with a sparingly water-soluble one or more hydroxamic acids of the general formula (I)
• R represents a straight-chain or branched, saturated or unsaturated alkyl radical having 6 to 22 carbon atoms, cycloalkyl radical or aryl radical having up to 19 carbon atoms, and containing organic solvents,
• a sulfidating agent is added to the organic phase
• organophase is worked up and / or re-sharpened and recycled in a manner known per se
• the interfering metal re-extracted into the water phase may be reductive in a manner known per se and worked up as a by-product.
• the method according to the invention falls under the generic term of the so-called "solvent extractions”. This usually means processes in which two liquid, more or less immiscible or mutually insoluble phases are brought into intimate contact with one another and a transition of one or more components from one phase to the other takes place, usually an equilibrium depending on various external parameters is established. Such parameters are described below for the individual process steps.
• Interfering elements in the description and also in the patent claims are understood to mean the elements arsenic, antimony, bismuth and iron, which - depending on the raw materials used and the smelting methods used - are more or less large, but in any case disturbing Concentrations in the electrolyte solutions which can be freed from the elements mentioned according to the invention, in particular in the electrolyte solutions of copper refining electrolysis. This can be one or more of the elements mentioned in different oxidation states.
• the interfering element arsenic can be present in the oxidation stage (III) or the oxidation stage (V) in such aqueous solutions.
• the above-mentioned interfering elements are preferably separated from aqueous solutions which originate from processes of copper refining electrolysis in which the element arsenic is generally the main constituent of this interfering element mixture.
• the method according to the invention is not limited to the separation of the interfering elements from such solutions. It is also possible to separate one or more of the above-mentioned interfering elements or all four from aqueous solutions containing copper, zinc, nickel or other valuable metals which originate from other sources or are obtained in other processes.
• the first step of the process according to the invention consists in adding aqueous, mineral acid, valuable metal electrolyte solutions to add a slightly water-soluble organic solvent or extracting agent which contains one or more hydroxamic acids of the general formula (I),
• R represents a straight-chain or branched, saturated or unsaturated alkyl radical having 6 to 22 carbon atoms or a cycloalkyl radical or aryl radical having up to 19 carbon atoms.
• inert organic solvents which are poorly miscible or soluble in water are, for example the following compounds in question: aliphatic, cycloaliphatic or aromatic hydrocarbons or their mixtures with a high boiling point, chlorinated hydrocarbons, ketones or ethers with a high boiling point or also mixtures of such compounds.
• hydrophobic character of the organic solvents also largely determines the nature of the extractant contained in this solvent or extractant.
• a hyroxamic acid of the general formula (I) or a mixture of several such hyroxamic acids of the general formula (I) functions as such.
• the radical R in the abovementioned general formula can be straight-chain alkyl radicals from the group consisting of hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, uneicosyl or docosyl .
• R in the abovementioned general formula (I) to represent the branched chain isomers of the straight-chain alkyl radicals mentioned.
• saturated alkyl radicals there can also be unsaturated alkyl radicals, which can also be straight-chain or branched.
• Hydroxamic acids of the general formula (I) are preferably used as extractants, in which R represents branched, saturated alkyl radicals having 6 to 22 carbon atoms, preferably branched, saturated alkyl radicals having 7 to 19 carbon atoms.
• hydroxamic acid (s) used as extractant (s) must dissolve as well as possible in the organic solvent and that it has the required stability in this solvent, one or more hydroxamic acids are particularly advantageous of the general formula (I) used, in which R represents neo-alkyl radicals of the general formula (II)
• radicals R 1 , R 2 and R 3 in which the sum of the C atoms of the radicals R 1 , R 2 and R 3 is in the range from 6 to 18.
• R 1 , R 2 and R 3 can be the numerous different isomeric residues from the group neo-heptyl, neo-octyl, neo-nonyl, neo-decyl, neo-undecyl, neo-dodecyl, neo-tridecyl, neo-tetradecyl, neo-pentadecyl, neo-hexadecyl, neo-heptadecyl, neo-octadecyl and neo-nonadecyl.
• the individual meanings of the radicals R 1 , R 2 and R 3 are of secondary importance in this context
• the hydroxamic acids of the general formula (I) which can be used in the process according to the invention can be prepared by processes which are generally known from the prior art.
• the corresponding Carboxylic acid is converted into the corresponding acid chloride by reaction with an excess of SOCl 2 and then reacted with hydroxylamine to give the hydroxamic acid of the general formula (I).
• it is also possible cf. J. Chem. Research (S) 1982, 90) to react the carboxylic acid and subsequently react it with hydroxylamine to give the corresponding hydroxamic acid of the general formula (I).
• other methods known from the prior art for producing such compounds (I) can also be used.
• Such hydroxamic acids (I) are prepared by the processes mentioned above from the products available from Shell Chemical Corporation under the trade name Versatic acid R. In one case they contain a neo-alkyl radical of the general formula (II) in the molecule of the general formula (I) at the position denoted by R, in which the sum of the C atoms of the radicals R 1 , R 2 and R 3 is 8 , and in the other case those compounds (I) in which the radical R represents neo-alkyl radicals of the general formula (II) in which the sum of the C atoms of the radicals R 1 , R 2 and R 3 is in the range from 7 to 17. Products of this type represent a technical mixture of hydroxamic acids of different chain lengths.
• hydroxamic acids are extremely stable in the pH ranges customary in such valuable metal electrolyte solutions and do not extract any free mineral acid either at room temperature or in the elevated temperature range, in particular no sulfuric acid from copper electrolyte solutions.
• organic phases containing hydroxamic acids have a viscosity in such a range that an optimal phase separation is ensured after the mixing process discussed below. Problems in separating the organic from the aqueous phase are avoided in this way.
• the second step of the process according to the invention consists in intensively mixing the aqueous and the organic phase with one another over a sufficient contact time.
• the contacting time of the two phases is one of the parameters on which the extracted amount of interfering elements, in particular the extracted amount of arsenic, depends.
• the majority of the interfering elements antimony, bismuth and iron are extracted.
• the relative amount of arsenic taken up in the organic phase is significantly lower.
• the aqueous and the organic phase are preferably mixed intensively with one another over a period of 1 to 60 min, particularly preferably over a period of 10 to 20 min. During this time, a large part of the arsenic contained in the copper electrolyte solutions has also passed into the organic phase.
• Another important parameter for the extracted amount of interfering elements lies in the concentration of hydroxamic acids of the general formula (I) or their mixtures.
• the amount of extractant in the organic phase is limited by the fact that at high concentrations of the hydroxamic acids (I) in the organic phase the viscosity increases so much during loading with the interfering elements that, in a continuous procedure, efficient mixing of the two phases no longer occurs can be guaranteed.
• the separation of the organic from the aqueous phase becomes significantly more difficult with increasing viscosity.
• organic solvents such as kerosene or mixtures thereof in the process according to the invention which contain one or more hydroxamic acids of the general formula (I) in a concentration of 0.1 to 2.0 mol / l organic phase, preferably in a concentration of 0.5 to 1.0 mol / l organic phase.
• the temperature at which the two phases are brought into contact with one another is usually in the range from 20 to 70 ° C., preferably in the range from 30 to 60 ° C. Electrolyte solutions drawn off from the process have temperatures in the range of 50 to 70 ° C due to the process. With a continuous procedure, separate heating of the mixtures in the mixer is no longer necessary. At a tem temperature in the range mentioned, both phases are mixed intensively. This can be done, for example, by feeding them to a so-called "mixer-settler" in a continuous process, mixing them together at the specified temperature for the specified time and allowing the phases in the settler to be separated.
• the organic phase which contains one or more hydroxamic acids of the general formula (I) and the extracted interfering elements arsenic, antimony, bismuth and iron, is drawn off from the aqueous phase.
• the organic, interfering element-laden phase is re-extracted with water over a sufficient contacting time. Even if this process step is carried out once, the arsenic interfering element is re-extracted into the water phase.
• the process parameters depend on the type (oxidation level) and amount of arsenic present in the organophase. For example, As (III) ions are re-extracted into the water phase comparatively faster than As (V) ions. This is explained in the following by examples.
• the contacting time influences the distribution of the interfering metals between the organic and the aqueous phase.
• the time in the present invention has a time of 1 to 20 minutes, preferably 10 to
• the temperature at which the two phases should be kept in contact with one another is usually in the range from 20 to 80 ° C., preferably 50 to 70 ° C.
• the volume ratio of organic phase to added water phase should, if possible, be set so that the organic phase contacts with such an amount of water becomes that a phase separation after the re-extraction is still possible in principle in order to obtain an aqueous phase with the highest possible interfering metal content, which can be worked up without concentrating the water phase.
• a metal ion mixture is obtained during the re-extraction in the aqueous phase, which contains, in addition to the main component arsenic, a minor component antimony.
• the interfering metal re-extracted into the water phase is optionally reductively precipitated and worked up as a by-product.
• a reducing agent for example sulfur dioxide or sulfur Hydrogen.
• the pure precipitate of arsenic trioxide or arsenic trisulfide obtained in this way can be processed further in a manner known per se.
• arsenic and antimony are of particular interest for certain technical applications, for example for the electronics industry.
• the sixth step of the process according to the invention is to add a sulfidating agent to the organic phase.
• This process step is in the inventive method of importance insofar as the extraction takes place of the impurity elements from valuable-metal electrolyte solutions at very high concentrations of mineral acid (eg 150 to 250 g H 2 SO 4/1).
• An increase in the acid concentration that is usually possible for the re-extraction of interfering elements is practically ruled out for the separation of the interfering elements from such acidic solutions.
• re-extraction of the interfering elements by treatment of the organic phase with alkaline solutions cannot take place, since the hydroxamic acids of the general formula (I), especially in the more alkaline range, are not sufficiently stable.
• the sulfide precipitation of the interfering elements which can be carried out directly on the loaded organic phase in accordance with the method according to the invention circumvents in a simple and surprising manner the need for re-extraction of the interfering elements from the organic phase by treatment with strongly acidic or strongly alkaline aqueous readings.
• Suitable sulfidating agents in the process according to the invention are hydrogen sulfide (H 2 S) gas and / or anhydrous Sodium sulfide or sodium hydrogen sulfide. Hydrogen sulfide is preferably used. This is particularly well suited for the precipitation step, since it performs two functions simultaneously: on the one hand, H 2 S acts as a reagent for the precipitation of arsenic, antimony and bismuth from the organic phase, and on the other hand it regenerates (due to its "acid” Properties) the extraction reagent (the hydroxamic acid (s)) of the general formula (I).
• H 2 S acts as a reagent for the precipitation of arsenic, antimony and bismuth from the organic phase, and on the other hand it regenerates (due to its "acid” Properties) the extraction reagent (the hydroxamic acid (s)) of the general formula (I).
• the important control process parameters are the hydrogen sulfide pressure, the temperature during the precipitation process and the reaction time.
• the parameters mentioned can be varied over a wide range.
• To precipitate the sulfides of the interfering elements the addition of a stoichiometric or slightly above-stoichiometric amount of gaseous hydrogen sulfide is sufficient. This is brought about by introducing H 2 S in the amount pre-calculated on the basis of the amounts of the interfering elements in the electrolyte and by applying an inert gas, for example N 2 , to the reaction system.
• an inert gas for example N 2
• the HS pressure in the course of the precipitation process is also possible to set to a value from 0.1 to 50 bar, preferably to a value in the range from 0.5 to 1 bar.
• a H 2 S overpressure favors the precipitation of the arsenic sulfides in particular.
• the precipitation reaction can be carried out in a suitable glass vessel; the use of complex metal autoclaves is therefore not necessary.
• the use of an autoclave is generally required.
• the use of highly corrosion-resistant and therefore expensive autoclave materials eg Hasteloy steels
• autoclaves made from conventional steels for example V4A steels
• the completeness of the precipitation is also influenced by a further process parameter, namely the temperature.
• the temperature which are preferably in the range between 40 and 90 ° C., particularly preferably between 60 and 80 ° C., the sulfides of the interfering elements arsenic, antimony and bismuth are completely precipitated in the organic phase.
• the third process parameter, the reaction time is also important for the completeness of the precipitation and corresponds essentially to the residence time of the organic phase in the reaction vessel during the introduction of H 2 S.
• the reaction time must be set depending on the other parameters mentioned and is in preferred embodiments of the method according to the invention at 1 to
• the mutually influencing parameters of the sulfidation reaction can be coordinated by a few simple experiments.
• a reaction at 0.5 bar H 2 S pressure, a reaction time of 15 min and a temperature of the loaded organophase when the hydrogen sulfide was introduced at 80 ° C. have proven particularly useful.
• the interfering elements antimony and bismuth are precipitated 100% and arsenic to a large extent (80% and higher).
• a complete increase in pressure beyond this particularly preferred range or a correspondingly longer reaction time may be required for complete arsenic precipitation.
• the disruptive elements arsenic, antimony and bismuth are precipitated as sulfides and, after precipitation has ended, can be carried out in ways known per se are separated from the organophase in the seventh process step. This is usually done by filtering or centrifuging the organophase through a filter of a suitable size. However, it is also possible to allow the sulfide precipitates of arsenic, antimony and bismuth to settle in the reaction medium and to decant the supernatant organophase. Which method of separation is chosen depends on the consistency of the sulfide precipitates formed and on further process parameters and has no critical influence on the completeness of the recovery of the interfering elements.
• the filter cake with an acid, preferably a mineral acid, such as sulfuric acid, after filtering off the precipitated sulfides and before washing with an organic solvent as described above.
• the organophase obtained after the sulfide precipitation is preferably flushed exhaustively with an inert gas by blowing out. This will remove dissolved or excess residues completely expelled from H 2 S.
• the treatment can also be carried out by contacting the filter cake with the mineral acid in a separate closed vessel with intensive mixing. This washing step can be carried out continuously, the mineral acid used then being circulated and made available for the cleaning step of subsequent batches.
• the iron transferred from the valuable metal electrolyte solution into the organophase by one or more hydroxamic acids (I) is not precipitated under the conditions defined in more detail above.
• a re-extraction of the iron by treating the organophase with basic aqueous solutions is not possible due to the low stability of the extractants (hydroxamic acids) without losing a large part.
• the organophase after the removal of the other interfering elements as sulfides and a removal of excess hydrogen sulfide with a water-soluble complexing agent for iron directly or with an aqueous solution of one such complexing agent.
• Preferred water-soluble complexing agents for iron are compounds from the group consisting of hydrogen chloride, oxalic acid or P-organic acids, in particular hydroxyethane diphosphonic acid (HEDP), that is to say those complexing agents which are known to have a high affinity for iron. Of these, oxalic acid or hydrogen chloride are particularly preferred.
• the separation of iron as an inorganic chloro complex or oxalate or phosphonate is, like the other steps, from the concentration of the complexing agent in the organophase or with the addition of aqueous solutions of the complexing agent - in the aqueous phase, the treatment time of the organophase with the complexing agent or its aqueous solution and the reaction temperature;
• the process parameters mentioned are also interdependent. It has been shown in practice that the concentration of water-soluble complexing agent for iron in the organophase or the aqueous phase is advantageously at values of 0.1 to 2 mol of the complexing agent per liter, preferably at a concentration of 0.5 to 1 mol of the complexing agent per liter.
• contact times of 1 to 20 minutes, preferably more than 5 to 15 minutes, are required at such complexing agent concentrations. These treatment times apply to the execution of the complexing step at room temperature and can be reduced accordingly if the temperature is raised. It is particularly preferred to treat the organophase with 1 mol of oxalic acid or HEDP per liter of organophase or aqueous phase over a contact time of 15 min in a mixer-settler.
• the iron content can be reduced to 0.07 g / l, ie by almost a power of ten, from the organophase which had passed the sulfide precipitation stage and which then still contained 0.6 g of iron / l.
• the iron complex formed in the manner described above is re-extracted with water from the organophase in a ninth process step in a manner known per se.
• the organophase is brought into intimate contact with a sufficient amount of water, and due to the good water solubility of the iron complex, a complete transition into the aqueous one Phase is observed.
• aqueous complexing agent solutions are added, after intimate mixing with and subsequent separation from the organophase, they contain almost all of the iron extracted from the electrolysis solutions. If desired, the iron can be recovered from this aqueous phase by methods known per se.
• the iron contained in the organophase is completely converted into an inorganic chloro complex.
• the organophase In order to enable the organic phase and the hydroxamic acids contained therein to be recycled and thus made available for a new extraction cycle, the organophase must be largely, if not completely, freed from hydrogen chloride or free chloride ions.
• the organophase is extracted again with a secondary amine as the liquid ion exchanger, for example with the ion exchanger available under the trade name "Amberlite R LA2". The iron extracted in this way can then be re-extracted with water.
• the organophase is then washed free of chloride with water in order to make it and the hydroxamic acids contained therein usable for reuse in the extraction cycle.
• One to two stages of washing with water bring the chloride content in the organophase down to less than 50 ppm, and with controlled use of the hydrogen chloride introduced, even less than 30 ppm.
• a reduction in the chloride content in the organophase to a few ppm is preferred.
• the resulting organophase containing the hydroxamic acid (s) can then immediately be used again for the extraction of the interfering elements.
• the iron can also be precipitated by treating the organophase with aqueous hydrochloric acid (hydrochloric acid), in practice using 1 to 12 molar HCl, preferably 3 to 8 molar HCl, has proven.
• aqueous hydrochloric acid hydrochloric acid
• concentration of hydrogen chloride it must be ensured that the amount of the chloride ions to be regarded as water-soluble complexing agents is in the range given above, ie 0.1 to 2 mol of the complexing agent per liter of organic phase. This ensures that all of the iron is converted into the form of an inorganic chloro complex. This is then separated from the organophase after the addition of water with the aqueous, inorganic phase and contains all of the iron previously extracted with the organophase.
• hydroxamic acids of the general formula (I) do not extract any noteworthy amounts of free hydrochloric acid (similarly as indicated above for H 2 SO 4 ).
• the re-extraction of iron in the form of a chloro complex does not form chloride salts which are difficult to dissolve in water and which would then not be removable by treating the organophase with water.
• the process step of complexing the iron can also be included in the step of precipitating the interfering elements arsenic, antimony and bismuth as sulfides from the loaded organic phase.
• the corresponding re-extraction agents must then be placed together with the organophase in the precipitation vessel, which can also be an autoclave at high pressure of the hydrogen sulfide to be introduced.
• the precipitation reaction of the elements arsenic, antimony and bismuth then proceeds exactly as described above for the separate separation.
• the elements arsenic, antimony and bismuth are considered heavy soluble sulfides precipitated, and in this case iron is simultaneously transferred into the re-extraction medium used (aqueous complexing agent phase).
• hydrogen chloride as the re-extraction medium, however, the use of corrosion-resistant autoclave materials is required in comparison to the separate processing of the iron complexes described above, since hydrogen chloride attacks the less corrosion-resistant steels.
• the process step of iron re-extraction can precede sulfide precipitation.
• aqueous HCl is used as a complexing agent for iron
• the re-extracted iron phase additionally contains antimony and also small amounts of arsenic. This means that the iron is not readily obtained from the aqueous chloride phase obtained, i.e. can be re-extracted without separation of antimony and arsenic.
• the procedure described first ie the sequence of sulfide precipitation - separation of the sulfides - subsequent or joint iron extraction and / or iron re-extraction, is preferred.
• the aqueous phase remaining after the removal of the said interfering elements is worked up in ways known per se.
• this can consist, for example, in that, depending on the ores used for smelting the copper, further interfering elements, for example nickel, are removed.
• the organophase obtained essentially consists only of the solvents or extracting agents used and the extractants, ie one or more of the above-mentioned hydroxamic acids of the general formula (I).
• Such an organophase is then immediate bar suitable for reuse in the extraction cycle.
• the aforementioned procedure can be carried out continuously by continuously withdrawing a certain amount of the copper refining electrolyte solution from the electrolysis device and subjecting it to the partial process steps described above.
• the extraction of the interfering elements from a practice electrolyte solution can be carried out continuously in a mixer-settler.
• a practice electrolyte solution in g / l: 12.0 As, 0.030 Bi, 0.52 Sb, 0.30 Fe, 45 Cu, 10 Ni and 160 H 2 SO 4
• the relevant parameters described in the partial process steps only require a one-step extraction.
• the kerosene from Esso which is commercially available under the name "Escaid R 100", was used as the organic solvent or extractant.
• the hydroxamic acid used was from a mixture of carboxylic acids of the formula
• the organic phase had the following interfering metal concentration (in g / l): 6.5 As, 0.52 Sb, 0.03Bi and 0.30 Fe.
• Example 1 A practical electrolyte solution according to Example 1 was first extracted with 0.5 molar hydroxamic acid from Versatic R 1019 in Escaid R as described above. Thereupon, organic: aqueous became by re-extraction with water at 80 ° C and a respective dwell time of 15 min with different volume ratios
• the extractant concentration was 0.5 mol / l
• the organophase resulting after the re-extraction with water was placed in a closed container. Nitrogen was used as the inert gas.
• the reaction conditions were: Temperature 60 oC, H 2 S pressure 0.5 bar, reaction time 5 min, vigorous mixing during the introduction. The mixture was then flushed with nitrogen for about 30 min in order to remove H 2 S which was still dissolved.
• a 0.5 molar solution of the hydroxamic acid as described in Example 1 was used as the extractant.
• a synthetic H 3 AsO 4 solution dissolved in sulfuric acid (150 g / l H 2 SO 4 ), served as the aqueous electrolyte solution.
• the As (V) content corresponded to a concentration of 10 g / l. After loading (O / A ratio 1: 1, 60 min at room temperature), an organophase with 6.8 g / l As (V) resulted.
• a solution of As 2 O 3 in H 2 SO 4 (150 g / l) served as the aqueous electrolyte solution.
• the As (III) content again corresponded to a concentration of 10 g / l.

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