Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ib metal
Patent
1997-12-12
2000-04-04
Bos, Steven
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ib metal
423 99, 423139, 423DIG14, 216 93, B01D 1100, C22B 1500, C23F 100
Patent
active
060457635
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for working up ammoniacal solutions containing valuable metals, more especially copper-containing solutions, which reduces the consumption of ammonia and the unwanted discharge of salts in solvent extraction in relation to the prior art.
2. Discussion of Related Art
In the production of printed circuit boards for the electronics industry, the ammonium chloride solution used as the etching solution becomes enriched with copper during the continuous etching process. During this process, the copper content in such solutions increases continuously until, finally, a critical limit for the etching process is reached at a content of around 130 to 150 g of copper per liter. To enable processing of the circuit boards to be continued without interruption, excess copper has to be removed from the etching solution.
This can be done by various methods. For example, corresponding solutions are collected and concentrated by evaporation and, finally, the copper is recovered in the form of a salt, generally as copper hydroxide, by the addition of suitable precipitation reagents. Techniques such as these are expensive on energy and show poor selectivity and the copper obtained as end product is of inferior quality. Another disadvantage of this method is that there is no possibility of fully regenerating the spent etching solution and hence reusing it in the etching process.
EP-A-005415 discloses a process for removing copper from an etching solution used in solvent extraction. This process uses a weak extractant dissolved in an organic solvent which reduces the copper content in the etching solution after extraction from 160 g/l to around 97 g/l. .beta.-Diketones are preferably used as extractants in this process. The organic extraction solution is washed with water which gradually becomes enriched with large quantities of ammonium salts, ammonia and copper. Sodium hydroxide is added to the washing water which is then concentrated by evaporation, the ammonia being driven out and the copper being removed as copper hydroxide. The copper present in the organic phase is stripped with strong sulfuric acid and recovered from the aqueous solution by electrolysis. The process is operated on site, i.e. follows the etching process.
EP-A-036401 discloses a similar process. In this process, however, extraction is carried out in one or more steps with various extractants or mixtures thereof. For example, in addition to the .beta.-diketones known from EP-A-005415, hydroxy oximes are used as stronger extractants in this process. The copper content in the etching solution can thus be reduced to a total of 6.5 g/l. The process is extremely complicated on account of the need to use two separate extraction circuits and different reagents or mixtures thereof and/or to operate several different successive extraction stages and, for this reason, has never been adopted for practical application. In this process, too, the charged extraction solution is washed with mineral acid in order to free the organic phase from entrained ammonia.
Although the solvent extraction processes mentioned are more efficient by comparison with working up using precipitation reagents, they are still attended by certain serious disadvantages. For example, although the copper content in the extracted etching solution can be reduced to levels which, in principle, enable the etching process to be continued, the copper content is still very high at around 90 g/l or 6.5 g/l. This applies in particular to regeneration and reuse of the etching solution. The copper content cannot be reduced to values in the ppm range by these processes. Accordingly, the spent etching solution also cannot be completely worked up and reused which would be desirable in view of the total quantity of etching solution.
Although, with the introduction of new and more efficient extractants, such as for example LIX.RTM. 84, a ketoxime available from Henkel Corp., very low copper concentrations in the required ppm
REFERENCES:
patent: 3743585 (1973-07-01), Lowenhaupt et al.
patent: 3981968 (1976-09-01), Miller et al.
patent: 4012482 (1977-03-01), Natwig et al.
patent: 4083758 (1978-04-01), Hamby et al.
patent: 4222832 (1980-09-01), Hubred et al.
patent: 4252621 (1981-02-01), Reinhardt et al.
patent: 4507268 (1985-03-01), Kordosky et al.
patent: 5788844 (1998-08-01), Olafson
Industrial & Engineering Chemistry Research, 28(11): 1664-69 (Nov. 1, 1989) .
Kehl Ralf
Schwab Werner
Bos Steven
Drach John E.
Henkel Kommanditgesellschaft auf Aktien
Millson Jr. Henry E.
LandOfFree
Process for working up ammoniacal metal solutions including trea does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for working up ammoniacal metal solutions including trea, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for working up ammoniacal metal solutions including trea will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-361982