Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: sodium thiosulfate

Sortuj według:

Ogranicz wyniki do:

Thiosulfate leaching of silver from a solid residue after pressure leaching of industrial copper sulfides flotation concentrates

Wejman-Gibas K., Chmielewski T., Borowski K., Gibas K., Jeziorek M., Wodka J.

Physicochemical Problems of Mineral Processing

2015

Vol. 51, iss. 2

601--610

Hydrometallurgical recovery of silver from a solid residue after pressure leaching of a flotation copper concentrate from the Lubin Concentrator (KGHM Polska Miedz S.A.) was investigated. Thiosulphate leaching was examined with regard to the highest possible leaching efficiency and optimization process parameters. The effect of thiosulfate ions concentration within the range from 0.25 to 1.00 mol/dm3 at a constant ammonia concentration, and ammonia concentration within the range from 0.40 to 1.00 mol/dm3 at a constant thiosulfate concentration on leaching recovery of selected metals were examined. Moreover, the effect of copper(II) ions addition on silver leaching was studied. It was shown that the leaching recovery of silver increased with increasing thiosulfate and ammonia concentration. At the highest thiosulfate ions concentration, the observed silver leaching recovery was 60%. The best results were obtained at an ammonia concentration of 0.80 mol/dm3, where the leaching recovery of Ag reached 75%. It was established that addition of Cu(II) did not affect silver leaching. Nearly 100% efficiency of thioslulohate silver leaching was achieved by pretreatment of the solid residue after pressure leaching with NaOH solutions.

Indirect complexometric determination of cadmium(II) using sodium thiosulfate as a masking agent

Sreekumar N. V., Narayana B., Bhat N. G., Nazareth R. A., Hegde P., Manjunatha B. R.

Chemia Analityczna

2002

Vol. 47, No. 5

765-768

An indirect complexometric method is described for the determination of cadmium(II), sodium thiosulfate being used as masking agent. Cadmium(II) in a given sample solution is initially complexed with an excess of EDTA and the surplus EDTA is titrated with zinc sul-fate solution at pH 5.0—6.0 fhexamine), using xylenol orange as indicator. An excess sodium thiosulfate is then added and the EDTA released from the Cd-EDTA complex is titrated with standard zinc sulfate solution. Results are obtained for 1.06-53.00 mg of cadmium with relative errors š 1.51 % and standard deviations <0.25 mg. Cu(II), Hg(II), Pd(II), Tl(III), Au(III) and Sn(IV) interfere, but can be easily masked. The method is applied for the determination of cadmium in alloy solutions as well as in its complexes.

Opisano pośrednią kompleksometryczną metodę oznaczania kadmu(II) z zastosowaniem tiosiarczanu sodu jako czynnika maskującego. Kadm(II) w roztworze danej próbki początkowo kompleksuje się nadmiarem EDTA po czym nadmiar odczynnika odmiareczkowuje się roztworem siarczanu cynku przy pH 5.0-6.0 w obecności heksametylenoczteroaminy, wobec oranżu ksylenolowego jako wskaźnika. Następnie dodaje się nadmiar tiosiarczanu sodu i EDTA uwolniony z kompleksu Cd-EDTA miareczkuje się mianowanym roztworem siarczanu cynku. Wyniki oznaczania kadmu w ilościach 1.06—53.0 mg wykazały, że błąd względny nie przekracza š1.51%, a względne odchylenie standardowe nie przekracza 0.25 mg. Pierwiastki, które przeszkadzają— Cu(II), Hg(II), Pd(II), Tl(III), Au(ffl) i Sn(IV) mogą być łatwo maskowane. Metoda może być zastosowana do oznaczania kadmu w roztworach jego stopów oraz w jego kompleksach.

Radiation chemistry of solid thiosulfate: optical absorption spectra

Zagórski Z., Rafalski A.

Nukleonika

2000

Vol. 45, nr 1

109-113

Solid sodium thiosulfate, anhydrous and hydrated (5 H2O), was irradiated with 10 MeV electrons in a pulsed, high-dose (30 kGy) rate regime. The resulting optical absorption was measured by diffuse reflection spectophotometry (DRS) (absorption band in anhydrous salt at 360 nm, in hydrated salt at 418 nm). Absorption decays occurred at t1/2 = 80 h (anhydrous) and t1/2 = 9 h (hydrated) at room temperature. The yellowish radical ion formed in irradiated anhydrous thiosulfate was identified as [źS2O3]-, and not [źS2O3]3-, as proposed in previous nonoptical (EPR) investigations. The absorption spectrum of [źS2O3]- in a solid matrix was similar to the transient spectrum ascribed to the same radical, obtained by pulse radiolysis in aqueous solution, and had a lifetime many orders of magnitude shorter. A similar radical anion, but in the complex with adjacent water molecules from the hydration moiety, was observed in hydrated thiosulfate (Na2S2O3ź5 H2O).