| 摘要 |
PURPOSE:To reduce the cost and the environmental load of waste washing water and to enable continuous work without forming AgS, etc. by returning part or all of the overflow of a preliminary washing bath behind a fixing bath to the fixing bath and by adjusting the washing bath to 5-9 pH. CONSTITUTION:Behind a fixing bath >=1 preliminary washing bath is set, the overflow of each bath is returned to the precceding bath in succession, and the final preliminary washing bath is supplied with a replenisher for preliminary washing. Part or all of the overflow of the preliminary washing bath just behind the fixing bath is returned to the fixing bath. The preliminary washing bath is kept at 5-9 pH with an acid such as sulfuric acid, hydrochloric acid or acetic acid, carbonate, phosphate or the like. Thus, the amount of the replenisher is reduced, AgS, etc. are prevented from precipitating in a washing bath, sticking to a sensitive material, and staining the image, and the silver recovering efficiency is improved. |
