Reference

Recovery of gold and silver from ion-exchange resins

Recovery of gold and silver from ion-exchange resins. Kalocsai, Gyorgy; Fabics, Ferenc (Reanal Finomvegyszergyar, Hung.). Hung. Teljes HU 26353 O 28 Sep 1983, 12 pp. (Hungarian). (Hungary). 7727-54-0 and 7440-57-5 are also occured in this study. CODEN: HUXXBU. CLASS: IC: C22B011-00. APPLICATION: HU 80-415 22 Feb 1980. DOCUMENT TYPE: Patent CA Section: 54 (Extractive Metallurgy) Au and Ag are recovered from ion-exchange resins by chem. oxidn. of the resins at 400-800° with concd. H2SO4 (>90, preferably 96-100%) or oleum [8014-95-7] at 1:1 wt. ratio and with 0.05-0.25 or 0.25-0.5 wt.% (based on concd. H2SO4) persulfates, peroxides, preferably (NH4)2S2O8 and H2O2, or concd. or dil. HNO3 to remove the resins and recover the Au and Ag by conventional sepn. Optionally, O, O-contg. gas, or H2O vapor is fed into the soln. simultaneously, or after the completion of the acid treatment. Thus, Au or Ag was recovered from 20 g dried ion-exchange resin contg. 5-6% precious metals by mixing with 40 g concd. H2SO4 or oleum, added in portions, and heating at 700-800° for 2-3 h, or optionally 5 g (NH4)2S2O8 after 50% decompn. of the resin by 40 g oleum and heating for 1 h. The (NH4)2S2O8 can be substituted by HNO3. Ag 2 g was recovered from 20 mL Ag-contg. resin used for 200 mL 0.1 N AgNO3 soln., after drying, oxidn. with 50 g 10% SO3-contg. oleum and 2 g (NH4)2S2O8 at 700-800° by heating 5 h. .

Effect of perchloric acid on the molecular weight and yield of poly-THF

Effect of perchloric acid on the molecular weight and yield of poly-THF. Matsuda, Kazuo; Tanaka, Yoshiaki; Sakai, Takeyo (Ind. Res. Lab., Kao Soap Co., Ltd., Wakayama, Japan). J. Appl. Polym. Sci., 20(10), 2821-7 (English) 1976. CODEN: JAPNAB. DOCUMENT TYPE: Journal CA Section: 35 (Synthetic High Polymers) When 28% fuming sulfuric acid [8014-95-7] alone was used to catalyzed the prepn. of poly(THF) (I) [24979-97-3], the av. mol. wt. of the I was, at max., 1000-1100; but the addn. of small amt. perchloric acid [7601-90-3] to the system increased the I mol. wt. .apprx.8000. Increases in the amt. of perchloric acid increased the I mol. wt. and yield in a controllable manner.