Alkaline sulfur-containing lixiviants, including thiosulfate, polysulfides, and alkaline sulfide solutions, stand out as a promising class of alternatives to cyanide because of their low toxicity, high efficiency, and strong adaptability. In this paper, we summarized the research progress and remaining challenges in gold extraction using these noncyanide reagents. After a brief introduction to the preparation method, the transformation process of various sulfur-containing species in alkaline solutions was discussed. Thereafter, some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were presented from different aspects, including thermodynamics analysis, electrochemical dissolution, and leaching kinetics. Moreover, recent progress in in-situ generation of sulfur-containing anions from gold-bearing sulfide minerals was outlined as well. Gold passivation caused by sulfur species was discussed in particular because it is considered the greatest challenge facing sulfur-containing leaching systems. Alkaline sulfur-containing lixiviants are expected to serve as alternatives in industrial applications of gold extraction, particularly for refractory gold ores containing copper and carbonaceous matter.

A review of gold extraction using noncyanide lixiviants: Fundamentals, advancements, and challenges toward alkaline sulfur-containing leaching agents

The reaction between sulfur and sodium carbonate at 350 °C has been investigated, and the products of the reaction have been identified at room temperature by using IR and Raman spectroscopies. The...

Identification of the Products of the Reaction between Sulfur and Sodium Carbonate

Heating-temperature-dependent electrochemical-performance-enhanced surface structural evolution during chemical treatment of Li-rich layered material by sodium thiosulfate

The disproportionation of sodium thiosulfate to form sodium sulfite and elemental sulfur has been studied in the temperature range 495–548°K by means of X-ray photoelectron spectroscopy (XPS). The disproportionation started with an induction period, followed by a steady-state disproportionation rate regime, and ended up with a diffusion rate-controlling process. The duration of the induction period was inversely proportional to the temperature of heating. The disproportionation in the steady-state regime followed a first-order reaction rate law with the enthalpy and entropy of activation H* = 26.0 kcal/ mol and S* = -14.9 eu.

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S. G. Chang

Papers

Study of the Disproportionation of Sodium Thiosulfate by X-Ray Photoelectron Spectroscopy