DD153807A1 - METHOD OF RECOVERING RHENIUM FROM HARMFULLY MINERAL ACIDATES - Google Patents

Abstract

The invention relates to a process for recovering rhenium from highly contaminated, mineral acid digestion solutions using strongly basic anion exchanger. The aim of the invention is to process complex, heavily contaminated, mineral acid bypassing a previous neutralization in a particularly selective rhenium ion exchange process. For this purpose, the loaded ion exchanger is first washed out with weakly accumulated condensed water with simultaneous carry-over charge, subsequently flushed with a 0.7 to 3 molar ammonia solution, then treated oxidatively with an active chlorine-containing solution; Subsequently, the rhenium is eluted by means of a 1 to 2 molar Thiocyantloesung and then freed ion exchangers before the next sorption completely by Thiocyanationen that a Thiocyanatelution at a temperature of 338 degrees K by a 3 to 7 molar ammonium chloride solution followed by oxidative decomposition of Thiocyanatreste by a active chlorine-containing solution.

Description

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Tite l the invention

Process for recovering rhenium from highly contaminated mineral acid lufschlusslösungen

Field of application of the invention.

The invention relates to a process for recovering rhenium from highly contaminated mineral acid digestion solutions using a strongly basic anion exchanger.

Characteristic of the known solutions technis chen

A method (US Pat. No. 3,558,268) is known which uses a strongly basic anion exchanger with quaternary ammonium groups, which has been previously charged with thiocyanate, for rhenium recovery from aqueous solutions. The rhenium-slution is then carried out with a 1 to 2 molar thiocyanate solution, preferably as NH.SC1T, which makes the anion exchanger sorbent again.

In this case, rhenium-containing anion complexes, which have a lower valence than the Perrhenatform eluted. This leads in the course of the further workup of the eluate, which comprises in particular a constriction, cooling and crystallization, by hydrolysis to sparingly soluble, hochrheniumhaltigen, poorly filtered precipitates.

An oxidizing treatment of the eluate is eliminated because in this case the Thiocyanatinhalt is decomposed with undesirable side effects. The method is only applicable to aqueous solutions free of those ions with which sparingly soluble thioeyanate compounds are formed. Therefore, it is also required to adjust the rhenium-containing aqueous solutions with HaOH to a pH = 12 and then to filter them. Such solutions are virtually free of such metal ions.

In the processing of rhenium-containing mineral acid digestion solutions, in particular those from a leaching of mixed residues of cement copper and copper (I) chloride in dilute sulfuric acid, this requirement can not be met for economic reasons.

The precipitation deposits of alkali metal hydroxides and basic sulphates of copper, zinc, lead and cadmium which form with alkalis in the neutralization of these solutions include considerable rhenium contents. In multi-step, elaborate washing operations, filtrates with different rhenium contents are obtained, which represent a significant, circulating rhenium stock.

Other disadvantages include high chemical consumption and technical equipment requirements for coping with high pesticide throughputs and filtrate throughputs. The disadvantages of subsequent neutralization also occur in the leaching of the materials described above in hot water when exposed to atmospheric influences for more than six weeks.

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Z_iel the invention

The aim of the invention is to process complex, heavily contaminated mineral acid digestion solutions bypassing a previous neutralization in a "rhenium selective ion exchange process.

Explanation: the essence of the invention;

The invention has for its object to provide a method for recovering rhenium from highly contaminated mineral acid digestion solutions, especially those from the workup of mixed residues of cement copper and Eupfer (I) chloride, using a strong base anion exchanger with quaternary ammonium groups, in which the elution the rhenium is carried out by the rhenium-loaded anion exchanger by means of a thiocyanate solution, in the sorption phase avoids the contact between poorly soluble thiocyanate compounds forming metal ions and thiocyanate Anionenaustauscherpartikeln and can enter in the sorption phase no thiocyanate ions in the rhenium-free run.

According to the invention, this object is achieved in that the rhenium obtained from heavily contaminated, mineral acid digestion solutions, a strong base anion exchanger prepared on the basis of styrene-divinyl copolymers, with quaternary ammonium groups as exchange-active puncture units is used. After loading of the anion exchanger, the exchanger column with weakly acidified condensate and - in contrast to the usual exchange technology - with simultaneous turbulence to full bed stretch by means of an oxidizing gas stream, for example, existing

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from compressed air and steam, "compressed air and chlorine, compressed air and ozone, washed out *

This 0.5 "to 6 hours, preferably 2 hours," at temperatures between 313 ⁰ K and 363 ⁰ K, preferably 338 ⁰ K, expiring treatment is followed by a rinse with a 0.1 η sulfuric acid at 313 ⁰ K to 338 ⁰ K, preferably 333 ⁰ K, on.

Subsequently, the exchanger column with a 0.7 to 3 molar ammonia solution at temperatures between 288 ⁰ K and 3.13 ⁰ K, preferably 303 ⁰ K, rinsed. This treatment does not only lead to the complete displacement of the digestion filtrate adhering in the intermediate grain volume, but also to the elution of certain anion complexes, in particular of the copper and zinc, which are relatively strongly adsorbed by exchange resins of the types described. In addition, it was surprisingly found that the filtrates of the ammoniacal rinse with certain cations, in particular of potassium and thallium, are enriched. This provides a welcome cleansing effect for stubborn rhenium companion that reduces the quality of ammonium perrhenate.

In a further process step, the loaded, strongly basic anion exchanger is treated oxidatively with an active chlorine-containing solution, preferably a Katriumhypochloritlösung, at 293 ⁰ K to 313 ⁰ K, preferably 298 ⁰ K.

Thus, the rhenium-containing anion complexes of lower valence are oxidized into the perrhenate form and thereby the formation of poorly soluble, hochrheniumhaltiger and cumbersome reprocessed precipitates avoided in the further processing of the eluate. In the effluent filtrate, further impurities such as anion complexes of arsenic, phosphorus, molybdenum, tungsten and chemically similar components are included in this process step,

while rhenium is present therein at a concentration corresponding to less than 1 ^σ / Ό of the amount adsorbed on the anion exchanger. The exchanger column is then rinsed again with a 0.1 to 1.0 molar, preferably 0.7 molar, ammoniacal solution at 288 ⁰ K to 313 ⁰ K, preferably 303 ⁰ K. Thereafter, the anion exchanger is ready for the elution of the adsorbed Rheniuminhaltes.

In the subsequent process stage, the elution of the rhenium by means of a 1 to 2 molar thiocyanate solution, preferably a Amraoniumthiocyanatlösung in a conventional manner. Before the next sorption phase, in order to completely regenerate the anion exchanger, it is necessary to remove the thiocyanate ions completely. The Thiocyanatelution takes place at temperatures between 313 ⁰ K and 373 ⁰ K, preferably at 338 K, either by a 2 to 5 molar, preferably 4 molar, sodium chloride solution or by means of a 3 to 7 molar, preferably 6 molar, ammonium chloride solution. In this case, 85 to 90 f> of the adsorbed on the anion exchanger thiocyanate be converted to the Regenerierfiltrat

 In the following step, an oxidative decomposition of the thio which remains on the anion exchanger takes place.

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Cyanatreste by rinsing with a solution containing about 40 g dm ^J active chlorine. The solution used is preferably a sodium hypochlorite solution. Their pH is between 8 and 13, preferably 12.5. In addition to this, advantageously, but not absolutely necessary, a rinsing of the anion exchanger with a dilute mineral acid, preferably a 0.1 normal sulfuric acid made.

As a result of this procedure, the strongly basic anion exchanger is again completely sorption ready

 Kit according to the method of the invention it is possible

to process highly contaminated, mineral acid digestion solutions, especially those from the work-up of mixed cement copper and copper (I) chloride residues in a particularly selective rhenium ion exchange process using strong base anion exchangers with quaternary ammonium groups.

Although the potential loading capacity of the strong base anion exchanger for rhenium and its sorption yield is known to be particularly severely affected by chloride ions in the precursor solution, the process results in useful volume capacity values that exceed those of, for example, IDA chelites by 20 to 30 fold , It is a Sorptionsausbringen of> 97 »5 f ° and a complete elution with specific Eluatmengen of 3 to 5 volume units, based on the volume of the exchange resin, achieved.

Execution game.

The invention will be explained in more detail below using an exemplary embodiment.

Mixed residues of cement copper and copper chloride were subjected to sulfuric acid leaching, by means of a strongly basic anion exchanger was carried out from the rhenium-containing, highly contaminated, sulfuric acid digestion solutions, the recovery of rhenium.

The strongly basic anion exchanger, prepared on the basis of styrene-divinyl copolymers, had quaternary ammonium exchange units as exchange-active puncture units. groups on. It was a trimethyl ammonium type exchanger of the formula R ZT ^K (CHo) o_7 with a relative base strength of pK-g = - 1.7 »where R is the organic framework substance. The

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The exchange-active group is simply positively charged by the quaternary ammonium bond and binds anions of varying intensity. At the same molar anion concentration, the following lyotropic series is known for this purpose:

ClO ₄ "<ReO ₄ "<SCN"<HSO ₄ "<H ₂ AsO ₄ "<Cl"<SO ₄ ² ~

In this series, depending on the pH of the medium and the concentration of the solvent also other Anionenkoraplexe such. B. CuCIp ", CuClo", ZnCl ₀ ", HPO ₄ "", H0o ~, JO ^", MoOg "" and others, which are to be considered in the present invention to be processed digestion solutions as contaminating components into consideration. After loading of the anion exchanger, the exchanger column with hot, acidified to pH = 1 condensed water with simultaneous turbulence with

"3 - ^ -1 500 dnr m _H -> min compressed air and steam were leached and washed for a period of three hours, maintaining a temperature of 333 ⁰ K. Subsequently, a special rinse of the exchanger column with a 0.1 η sulfur was carried out acid at the same temperature and a charge of 1.4 molar ammonia solution at 293 ⁰ K. This was followed by further elution, in particular of copper and zinc, which form stable tetrammine complexes with ammonia, and filtrates of this purge with certain cations For example, the potassium and thallium enriched, which was a very beneficial cleaning effect of the persistent Rhenium companions, which reduced the quality of the ammonium perrhenate.Of course, the perrhenations bound by the anion exchanger were able to fix such cations with which they were sparingly soluble Forming connections By means of a concentration-dependent Verdrä In response to these reactions, those places have become

high supply of NEL ⁺ ions. In the passing filtrates rinsing with condensed water, sulfuric acid and ammonia, the Eheniumgehalte always were below 15 mg dm ^J.

The following process step consisted of oxidizing the lower-valence rhenium-containing anion complexes bound by the strongly basic anion exchanger into the perrhenate form. For this purpose, the anion exchanger with an approximately 40 g dm ^J containing free chlorine sodium hypochlorite solution was treated. This ensured that all of the amount of rhenium bound by the anion exchanger was present as perrhenate. Formally, this loading state corresponds to the structural formula * R £ $ (CH) ₃ JZ ₃ ^ eO ₄ .

The filtrate of this process step had a rhenium content corresponding to 0.4 # of the adsorbed G-esamtrhenium amount in the anion exchanger, it contained v / eitere impurities in the form of anion complexes of molybdenum, tungsten, arsenic, phosphorus and chemically analogous components.

Now, in a known manner, the elution of rhenium with a 1.75 molar ammonium thiocyanate solution.

After rhenium elution, all exchange-active centers of the strongly basic anion exchanger are coated with thiocyanate ions, which is formally characterized by the structural formula # R / ß (CH) ₃ _7 SCN. To completely regenerate the ion exchanger, removal of the thiocyanate ions was required. For this purpose, the anion exchanger was treated at 340 ⁰ K with a 4 molar sodium chloride solution. The regeneration filtrate contained 90 lbs. Of the thiocyanate adsorbed on the anion exchanger. In a further regeneration step, the residual thiocyanate still remaining on the anion exchanger was flushed with a sodium hypochlorite solution

oxidatively decomposed. The solution contained 40 gm of active chlorine and had a pH of 12.5. This step was complemented by a rinse with a 0 _t 1 normal sulfuric acid. Thereafter, the strongly basic anion exchanger of the trimethylammonium type was again completely sorption-ready.

Claims (8)

invention claim 1. A process for recovering rhenium from highly contaminated, mineral acid digestion solution with a strongly basic anion exchanger with quaternary ammonium groups, in which the rhenium elution with a 1 to 2 molar thiocyanate solution, preferably as ammonium thiocyanate, made, characterized in that the loaded, strongly basic anion exchanger - Washed out first with slightly acidified condensation while simultaneously vortexing to full bed extension by means of an oxidizing gas stream; - subsequently rinsed with a 0.7 to 3 molar ammonia solution; ~ then treated oxidatively with an active chlorine-containing solution; - In a subsequent process step in a conventional manner, the rhenium eluted by means of a 1 to 2 molar thiocyanate solution and - After the anion exchanger is completely freed from thiocyanate ions before the next sorption phase, that - A thiocyanate elution at a temperature between 313 ⁰ K and 373 ⁰ K, preferably 333 ⁰ K, either by a 2 to 5 molar, preferably 4 molar, saline or by a 3 to 7 molar, preferably 6 molar, ammonium chloride solution is carried out with then oxidative decomposition of the Thiocyanatreste by an active chlorine-containing solution. 216 914 2. A process for Rheniumgewinnung according to item 1, characterized in that passes as oxidizing gas stream either a mixture of compressed air and steam, compressed air and chlorine or compressed air and ozone for use. 3. A method for Rheniumgewinnung according to item 1, characterized in that the washing process with weakly acidified condensate with simultaneous turbulence to full bed extension by means of an oxidizing gas stream in a period of 0.5 to 6 hours, preferably 2 hours, and at temperatures between 313 ⁰ K and 363 ⁰ K, preferably at 338 ⁰ K occurs. 4. A process for rhenium recovery according to item 1, characterized in that the solution used for the oxidative decomposition of Thiocyanatresten in the Thiocyanatelution a content of -3 about 40 g dm ^{J has} active chlorine. 5. A method for rhenium recovery according to item 1, characterized in that the active chlorine-containing solutions are preferably Natriumhypochloritlösungen. 6. A process for Rheniumgewinnung according to points 1 and 2, characterized in that the active chlorine-containing solution has a pH between 8 and 13, preferably 12.5 ». 7. A process for Rheniumgewinnung according to item 1, characterized in that the rinsing with the 0.7 to 3 molar ammonia solution at a temperature between 233 ⁰ K and 3 ^ 3 ⁰ K _5, preferably at 303 ⁰ K, takes place. 8. A process for Rheniumgewinnung according to item 1, characterized in that at the end of the thiocyanate elution, a supplementary rinse with dilute mineral acid, preferably 0.1 normal sulfuric acid takes place.