Enrichment of trace amounts of gold, silver, palladium and platinum by precipitate flotation

Summary An organic precipitant, p-dimethylaminobenzilidenerhodanine (DABR), is used as the gatherer in precipitate flotation to enrich trace amounts of gold, silver, palladium and platinum from acidic media in the presence of surfactants. The DABR dissolved in dimethylformamide (DMF) does not affect the determination of the enriched metals with electrothermal atomic absorption spectrometry. The presence of a 10²- to 10⁴-fold excess of other usual ions does not interfere with the flotation owing to the high selectivity of DABR for the noble metals in acidic media. As little as 1 ng/l of gold in aqueous solution can thus be determined by AAS. The method has been applied to determine the noble metals in various ore samples with satisfactory results.Dedicated to Prof. Kuang Lu Cheng, University of Missouri, Kansas City, USA on the occasion of his 70th birthdayPresented in part at the Third China-Japan Joint Symposium on Analytical Chemistry, Hefei, China, May, 1988