Image Number 2 for United States Patent #8114189.
A method of reducing or preventing the amount of iron sludge or precipitate that forms as a result of the recovery of silver from chemical solutions, such as a standard photographic solution. The method generally involves the introduction of a source of a conjugate organic base, such as a weak organic acid like citric acid or a salt of the conjugate organic base like a citrate salt, to the chemical fluid either before or during the silver recovery process. Preferably the source of conjugate organic base is introduced by combining it with a binder to form a time release cake or placing it in a container that has a semipermeable membrane that maintains the concentration of the conjugate organic base in the chemical fluid from about 0.2 to about 78 milimolar over a period of time.
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