Abstract: The invention relates to a process for working up charged aqueous solutions, more especially etching solutions, which contain ammonia, at least one ammonium salt and metal ions in dissolved form and which accumulate in the treatment of substrates containing valuable metals, more especially copper-containing electronic sub-assemblies by contacting the aqueous solution with an organic water-immiscible extractant in one or more extraction stages to form an organic phase containing valuable metals and an aqueous phase, (b) washing the organic phase with a water-containing liquid in one or more successive washing stages wherein the water-containing liquid has a pH above 6.5 in the first washing stage and after said washing stage contacting the washing water before reuse with an organic extraction solution, and (c) conducting one or more stripping stages to transfer the valuable metals from the organic phase to an aqueous phase.

Abstract: A process is disclosed for removing impurity elements, such as arsenic, and if necessary antimony, iron or bismuth, from valuable metal containing, such as copper containing, strongly mineral acid solutions by way of solvent extraction with organic solutions of hydroxamic acids, and for selectively stripping the impurity elements therefrom. Antimony, iron or bismuth are stripped with complexing acids, and arsenic is stripped with an aqueous solution containing valuable metal ions at a pH value in the 1.5 to 5 range, a higher pH than the original valuable metal containing aqueous acid solution.

Abstract: A process is disclosed for the two-phase extraction of metal ions from phases containing solid metal oxides, which is characterized in that the solid metal oxides are brought into contact with a hydroxamic acid, known per se, dissolved in a hydrophobic organic solvent, the phases containing the solid metal oxides and the organic phase are intensively intermixed over a sufficient contact time, after phase-splitting, the organic phase is separated and the metal ions are re-extracted from the organic phase in a manner known per se and processed.The extracting agent used therein and the use of this extracting agent are also disclosed.

Abstract: Prior art processes for removal of one or more contaminant elements, including at least one of antimony, bismuth, and arsenic and optionally including iron, from electrolyte solutions of primary metals by solvent extraction with an organic phase including a hydroxamic acid, then precipitating at least part of the contaminant elements from the organic phase as sulfides, are improved by an additional step of re-extracting the organic phase with water before precipitating the sulfides from it. At least part of any arsenic present and, if desired, part of any antimony as well, may be re-extracted in this manner and subsequently recovered if desired, so that the overall process is made more economical.

Abstract: A process for the common or simultaneous separation of arsenic, antimony, bismuth and iron from electrolyte solutions of valuable metals by solvent extraction and subsequent recovery of the contaminating elements, which process is characterized in that aqueous mineral-acidic electrolyte solutions of valuable metals are admixed with a sparingly water soluble organic solvent containing at least one hydroxamic acid, the aqueous and organic phases are thoroughly mixed, the contaminating elements arsenic, antimony and bismuth are precipitated from the organic phase by direct sulfide precipitation, the sulfides are separated, and the extracted iron is subsequently reextracted with a water soluble iron-complexing agent into an aqueous phase and recovered.

Abstract: Citric acid partial esters corresponding to the following general formula ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 represent hydrogen or a straight-chain or branched C.sub.4 -C.sub.20 alkyl radical or a metal atom, with the proviso that at least one but at most two of the substituents R.sup.1, R.sup.2 and R.sup.3 represent such an alkyl radical, or mixtures of the citric acid partial esters corresponding to general formula (I), are used for the extraction of iron from aqueous solutions.