都市廃棄物の処理と資源化に関する基礎的研究(VI) : 含銀写真廃液の処理

概要

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The recycling of high-purity silver from photosensitizer, i.e. spent fixing solutions has been carried out to resourcify the silver scrap and to reuse fixing solution by the following flotation and thermal decomposition processes. 1) Selective precipitation of silver as silver xanthate from spent fixing solutions in which silver ion is dissolving as Ag(S_2O_3)_3^<5-> and Ag(S_2O_3)_2^<3-> ions. 2) The reaction between Ag^+ ion and xanthate ion was investigated by EMF method utilizing Ag electrode and the EMF was found to be very useful to controll the reaction, especially to find the end point of the reaction. 3) The solubilities of various alkyl xanthates of silver were determined by EMF method at 25℃, μ=0 and μ=3. 4) Thermal decomposition of silver xanthates resulted in production of pure silver metal via silver sulfide and sulfate. 5) Side reactions of silver xanthates formation were found to take place in the presence of excess amount of Ag^+ and OH^- producing Ag_2S. 6) Recovery of xanthate ion from silver xanthates was examined using the substitution reaction between silver xanthate and OH^- ion. 7) The flotation of silver xanthates resulted in good recovery of silver even from highly concentrated S_2O_3^<2-> ion solutions.recyclingsilverphoto-fixingspent photosensitizersilver xanthates thermal-decompositionsilver sulfidesilver sulfatescrap
東北大学の論文
1986-09-30