PURPOSE: To recover economically and efficiently silver from waste liquor contg. a silver salt by adjusting the waste liquor to a specified pH, adding a small amount of an alkali metallic hydridoaluminate, and carrying out solid-liq. separation.
CONSTITUTION: Waste liquor contg. a silver salt such as a spent photographic fixing soln. is adjusted to 4W<8pH by adding a basic compound such as ammonia or NaOH, and at least one kind of compound selected among alkali metallic hydridoaluminates such as lithium aluminum hydride and alkali metallic hydridoborates potassium borohydride is added to the waste liquor by about 0.4W1.5mol per 1mol silver in the waste liquor. The waste liquor is then stirred at 5W100°C for ≥about 30min to carry out reduction treatment. After finishing reduction, precipitated silver is recovered by solid-liq. separation.
YAMAKAWA ISAO
FUJIWARA SAIJIRO
OHASHI HITOSHI
HARADA KOICHI
TAKASUGI TAKESHI
