Thiocyanate Hydrometallurgy For the Recovery of Gold Part III: Thiocyanate Stability

Editor(s)

Petersen, Jochen

Abstract

The effects of metal ions, minerals, temperature, thiocyanate concentration, activated carbon, and pH on the rate of thiocyanate oxidation were determined. The rate of ferrous ion generation from the redox reaction between thiocyanate and ferric ion was found to be significant at 50 °C. The reaction constant (k) at 25 °C was found to be 1.43 × 10− 5 L0.4 mol− 0.4 min− 1. Ferric oxidation of thiocyanate was sensitive to temperature with an activation energy of 76.4 kJ/mol, typical of homogenous chemical reactions. Based on the kinetic data, the empirical rate equation for thiocyanate consumption and/or ferrous ion generation was found to have the following form: d[Fe2+]dt=−8d[SCN−]dt=k[SCN−]1.36[Fe3+]0[H+]0=k[SCN−]1.36 Oxide minerals did not have a profound effect on the oxidation of thiocyanate by ferric ion. Sulfide minerals, especially pyrite and galena catalyzed the redox reaction. The addition of cupric ion resulted in the oxidation of thiocyanate and formation of an insoluble cuprous thiocyanate compound.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Thiocyanate; Oxidation; Sulfide Minerals; Activation Energy; Activated Carbon

International Standard Serial Number (ISSN)

0304-386X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Elsevier, All rights reserved.

Publication Date

01 Feb 2012

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