Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G47/00—Compounds of rhenium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G47/00—Compounds of rhenium
  • C01G47/003—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
  • C22B61/00—Obtaining metals not elsewhere provided for in this subclass
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• the invention relates to a process for the preparation of pure ammonium perrhenate by reaction of perrhenic acid with ammonia, and high-purity ammonium perrhenate.
• the object of the present invention is therefore to provide a simple process for preparing a pure aminium perrhenate, which is characterized by a high space-time yield, requires much less energy and is thus more environmentally friendly than the conventional processes.
• the invention is based on the finding that nitrite ions produced cathodically from nitrate ions react with ammonium ions to form water and molecular nitrogen, and in this way a suspension of ammonium perrhenate in the presence of nitric acid can be converted into a concentrated perrhenic acid solution.
• the present invention therefore provides a process for the preparation of pure ammonium perrhenate, comprising the following steps:
• ammonium perrhenate an ammonium perrhenate (NH 4 ReO 4 ) which contains impurities such as K, Na, Ca, Mg, Fe, Cu, Mo, Si up to 100 ppm and above.
• impurities such as K, Na, Ca, Mg, Fe, Cu, Mo, Si up to 100 ppm and above.
• a particularly undesirable impurity in the ammonium perrhenate and in the end products produced therefrom such as perrhenic acid, rhenium oxides (ReO 2 , ReO 3 ) and rhenium metal is the potassium.
• a certain Share of potassium already be removed as insoluble potassium perrhenate from the concentrated perrhenic acid.
• the concentration of nitric acid in the suspension may be 0.5 to 10 mol / l, preferably 0.5 to 8 mol / l, more preferably 0.5 to 7 mol / l, particularly preferably 1 to 5 mol / l. Good results are achieved with a concentration of nitric acid of 2 to 4 mol / l.
• the supply of nitric acid can be batchwise or continuously. The continuous supply of nitric acid has the advantage that the amount required in each case is automatically adapted to the current flowing through the electrolysis and the entire process can be optimally controlled.
• the suspension is circulated by means of a pump through the cathode space.
• the electrolytic cell and the reservoir can be maintained at different temperatures and the life of the cation exchange membrane can be considerably extended.
• the temperature in the electrolysis cell can generally be in the range from 20 to 100 ° C. The temperatures above 80 0 C, however, lead to increased corrosion in the electrolysis cell and thereby reduce their life.
• the temperature in the electrolytic cell 20-80 0 C preferably 30-70 0 C.
• a particularly preferred temperature in the electrolytic cell of 40-60 ° C remains the corrosion largely.
• the temperature of the suspension in the reservoir should not fall below 50 ° C in order to achieve a sufficiently high rate of decomposition of the ammonium ions.
• the temperature in the reservoir is> 60 ° C, preferably> 70 0 C, more preferably> 80 ° C and particularly preferably> 95 ° C.
• a very important role in the process according to the invention is played by the current density at which the cathodic reduction of nitric acid (HNO 3 ) to nitrous acid (HNO 2 ) takes place or is operated with the electrolysis cell.
• the reduction of nitric acid can be carried out at current densities of 100 to 4000 A / m 2 .
• the reduction is preferably carried out at current densities of 100 to 3000 A / m 2 , preferably 300 to 2000 A / m 2 . In a particularly preferred embodiment, the reduction is carried out at a current density of 500 to 1000 A / m 2 . In this area particularly long life of the cation exchange membrane can be achieved.
• an aqueous perrhenic acid which may contain up to 300 ppm potassium and other impurities, is directly produced in the electrolytic cell according to the invention.
• the quality of the perrhenic acid thus obtained is already sufficient and this can be used directly or after a subsequent complete reaction with ammonia as pre-purified ammonium perrhenate.
• the quality is not yet sufficient, since the potassium content of such perrhenic acid is still too high.
• the ammonia can be fed to the reaction system as a concentrated aqueous ammonia solution (25%) or in gaseous form.
• the supply of ammonia can also be carried out as a mixture consisting of gaseous ammonia and an aqueous ammonia solution.
• the above-described supply forms of ammonia have the advantage that thereby the reaction volumes can be kept small and the necessary proportion of the pre-precipitation is minimized.
• the potassium ions are removed via cation exchangers in the protonated form from the perrhenic acid obtainable in the first step.
• stoichiometric amounts of ammonium ions are removed via cation exchangers, resulting in dilute perrhenic acid from ammoium perrhenate solutions, only traces of potassium are removed in the process according to the invention.
• the very complex regeneration cycles are reduced to a minimum.
• the purified perrhenic acid is mixed with at least a stoichiometric amount of ammonia to obtain purest ammonium perrhenate.
• An excess of ammonia of 5 to 20% based on the stoichiometric amount is advantageous to ensure the quantitative neutralization of perrhenic acid.
• Ammonium perrhenate as a solid (5) prepared a suspension.
• Ammonium perrhenate as a solid (5) prepared a suspension.
• the dip tube (6) with a pump (7) low-solids suspension through the heat exchanger (8) in the
• Electrolytic cell (10) promoted. Through the free overflow (11), the catholyte flows back into the reactor (1). In the reactor (1) via the heat exchanger (3) has a temperature of > 50 ° C maintained. Before the low-solids suspension is pumped into the cell with the pump (7), the heat exchanger (8) may cool it down to ⁇ 80 ° C.
• the anolyte of the electrolysis cell (10), consisting of perrhenic acid, is conveyed from a circulation tank (12) with pump (13) into the anode compartment of the two-part electrolysis cell (10) and flows back through the free overflow (14) into the circulation tank (12) , In this is cooled by means of the heat exchanger (15) and by adding demineralized water via pump (16) the losses are compensated by water decomposition and transfer into the cathode compartment.
• After commissioning of the two circuits is pumped (17) nitric acid into the reactor (1) and adjusted in the electrolytic cell (10) of the current by applying a suitable voltage.
• the pressure filter (21) serves to separate any precipitated potassium perrhenate already here (23).
• the perrhenic acid which may contain up to 300 ppm, or 400-500 ppm of potassium (based on rhenium), collected.
• pump (24) this perrhenic acid is sent for further processing.
• the further processing of the potassium-containing perrhenic acid to purest ammonium perrhenate can be carried out in different ways.
• the purification is preferably carried out by means of a precipitation of the ammonium perrhenate, FIG. 2.
• the potassium-containing perrhenic acid is pumped by pump (24) into the precipitation reactor (25). While stirring (26), the solution is cooled with heat exchanger (27).
• the extracted Mother liquor can be fed via pump (39) to the earlier process stages of rhenium production or fed back to the reactor (1) via pump (4).
• the purest ammonium perrhenate is removed from the suction filter via (40) and further processed, for example, by reduction to give the purest re-metal powder.
• an ion exchanger is used. After this process, the potassium-containing perrhenic acid after cooling in the reactor (26) is conveyed by the pump (29) through the ion exchange column (42) in the reactor (32). The ion exchange column is previously filled via (41) with cation exchanger in the protonated form so that the potassium ions contained in the perrhenic acid are exchanged for H + ions. The perrhenic acid then contains less than 5 ppm of potassium, based on rhenium. The main reactor (32) then precipitates the purest Ammoniumperrhenates, as described above. If the ion exchanger no longer absorbs enough potassium, it is fed to (43) regeneration with mineral acids.
• the invention also relates to a novel ammonium perrhenate which contains less than 5 ppm of potassium, preferably less than 3 ppm of potassium, and more preferably contains less than 1 ppm of potassium.
• the ammonium perrhenates of the invention may have different morphologies in terms of particle or agglomerate form, e.g. platy, irregularly shaped, rod-shaped or spheroidal.
• the ammonium perrhenates according to the present invention are particularly distinguished by the spheroidal shape of the crystal agglomerates.
• the size of the crystal agglomerates may be greater than 10 ⁇ m, preferably greater than 20 ⁇ m, particularly preferably greater than 30 ⁇ m and particularly preferably greater than 50 ⁇ m.
• Such ammonium perrhenates can be prepared by the method described above.
• the Ammoniuimperrhenat according to the present invention is a particularly pure product and is characterized for example by its purity of at least 99.999% based on the total mass of the product.
• ammonium perrhenates according to the present invention can be used as precursors for the preparation of particularly pure rhenium compounds and rhenium metal.
• the rhenium metal is particularly suitable as an alloying metal for the production of superalloys, as well as for the coating of X-ray rotary anodes. The invention will be explained in more detail with reference to the following examples. Examples
• the anolyte of the electrolytic cell (10) consisted of 40% HReO4 and was conveyed from a circulation tank (12) with pump (13) into the anode compartment of the two-divided electrolysis cell (10) and flowed through the free overflow (14) in the circulation container (12) back.
• a temperature of 30 0 C was maintained by means of the heat exchanger (15).
• the losses were compensated by water decomposition and transfer into the cathode compartment.
• 705 g / h of nitric acid (50%) were pumped into the reactor (1) with pump (17) and a current of 300 A was set in the electrolysis cell (10) by applying a voltage of about 4 V.
• Examples 3-5 were carried out analogously to Example 2, wherein the proportion of pre-precipitated Ammoniumperrhenates was gradually increased.
• Table 1 the parameters and the results of Examples 2 to 5 are summarized.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catalysts (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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• 2008
  • 2008-06-05 DE DE102008026910A patent/DE102008026910A1/de not_active Ceased
• 2009
  • 2009-04-29 WO PCT/EP2009/055174 patent/WO2009146986A1/de active Application Filing
  • 2009-04-29 US US12/996,016 patent/US8795509B2/en not_active Expired - Fee Related
  • 2009-04-29 JP JP2011512053A patent/JP2011522127A/ja not_active Ceased
  • 2009-04-29 EP EP09757369A patent/EP2291327A1/de not_active Withdrawn
  • 2009-04-29 CA CA2726438A patent/CA2726438A1/en not_active Abandoned
  • 2009-04-29 RU RU2010154378/05A patent/RU2514941C2/ru not_active IP Right Cessation
• 2014
  • 2014-06-20 US US14/309,902 patent/US20140301939A1/en not_active Abandoned

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