Jewel scrap recycling for the silver hydrometallurgical recovery

Carol Elizabeth Barrientos Rojas, Afonso Henriques Martins

Abstract


A great amount of scrap metal wastes are lost in the manufacturing of jewelry due the lack of knowledge of precious metals recovery. This work presents the experimental results in a bench laboratory scale for the use of a hydrometallurgical route to treat gold jewelry scrap using samples with Ag contents higher and lower than 10%. The adopted route consisted of leaching of jewelry scrap with HNO3 to extract Ag and it was used the complete Factorial Method with two experimental levels to evaluate the influence of some variables, such as, leaching time, aqueous leaching solution temperature and solid/liquid ratio, on the metallic extraction percentage. The ascending path method for statistical optimization was used after the factorial method aiming at determining the optimum experimental conditions to reach the maximum Ag extraction percentage. The leaching liquors were treated and three methods were evaluated for the Ag recuperation. The optimum conditions for total Ag leaching with HNO3 were: 32mL of HNO3, 1.5 h and 42°C for sample 1 (higher than 10% Ag) and 45mL of HNO3, 2.25h and 43°C for sample 2 (lower than 10% Ag). The best result for Ag recovery (94%) occurred by the AgCl calcination obtained with the NaCl added to the HNO3 liquor.

Key words: silver, scrap jewelry treatment, leaching, hydrometallurgy.

Full Text: PDF (Português (Brasil))



ISSN: 1808-7310 - Best viewed in Mozilla Firefox

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