Process for desilvering silver halide processing fluids

A method to reduce dissolved silver present in spent, waste, photographic processing fluids containing thiosulfate, is described. This process involves adjusting the pH to a low level prior to the addition of finely ground steel to the solution. With the pH at the low level, e.g. 2.5, the reaction o...

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Bibliographische Detailangaben
Hauptverfasser:	BOOKER, BARBARA T
Format:	Patent
Sprache:	eng
Schlagworte:	CALCULATING CHEMISTRY CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F COMPUTING COUNTING ELECTRIC DIGITAL DATA PROCESSING FERROUS OR NON-FERROUS ALLOYS GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS INORGANIC CHEMISTRY METALLURGY PHYSICS PRETREATMENT OF RAW MATERIALS PRODUCTION AND REFINING OF METALS TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE TREATMENT OF ALLOYS OR NON-FERROUS METALS
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Beschreibung
Zusammenfassung:	A method to reduce dissolved silver present in spent, waste, photographic processing fluids containing thiosulfate, is described. This process involves adjusting the pH to a low level prior to the addition of finely ground steel to the solution. With the pH at the low level, e.g. 2.5, the reaction of dissolved silver to precipitated silver, is facilitated. However, the pH must then be raised or neutralized, e.g. 7-8.5, in order to insure that the dissolved silver is essentially all precipitated. This material can now be safely shipped without treatment as a hazardous material and, after filtering the solids therefrom, can be safely disposed.