Capillary electrophoretic analysis of sulfur and cyanicides speciation during cyanidation of gold complex sulfidic ores

Abstract

A capillary electrophoretic protocol for the separation and quantification of the most important species potentially liberated during the cyanidation of gold sulfide-rich ores was accomplished in this study. The separation of 11 ions: S2O3(2-), Cu(CN)3(2-), Fe(CN)6(4-), Fe(CN)6(3-), SCN(-), Au(CN)2(-), Ag(CN)2(-), SO4(2-), OCN(-), SO3(2-), and HS(-) was achieved using an indirect UV detection method. The robustness of the analytical protocol was tested by analyzing ions speciation during the cyanidation of two gold sulfide-rich ores. The 1-h cyanidation of the two ores released up to six complexes into solution: S2O3(2-), Cu(CN)3(2-), SCN(-), Fe(CN)6(4-), OCN(-), and SO4(2-). The mineralogy of the ore was found to influence directly the nature and the amount of the dissolved species. Conserving the cyanidation solution for 72 h after sampling resulted in 96% total sulfur recovery. These results allow us to conclude that the analytical protocol developed in this study can become very useful for the optimization of precious-metals cyanidation plants.

Speciation of Sulfides and Cyanicides in the Cyanidation of Precious Metal Bearing Ores Using Capillary Electrophoresis—a Review

“…Larachi and co-workers [18] successfully separated 11 ions, namely, S 2 O 3 contained all targeted ions except hydrosulfide (HS -), while in the second, hydrosulfide was replaced by cyanide complexes of Fe(III) [30] and Ag(I). [31] This action was taken because in reactions 13 and 14 Fe(III) and silver cyanide react with hydrosulfide affecting separation and quantification process of the targeted ions: 2 (10) Figure 3 shows the 11 anions separated and quantified in 2 anions standard mixtures by means of an indirect ultraviolet-visible detection protocol.…”

“…[15,[18][19][20][21][22][23][24] These investigations were generally performed in two instances: synthetic solutions prepared in the laboratory and actual aqueous samples received from mineral ore processing plants. This article presents a summary of important achievements on the speciation and quantification of inorganic sulfur, sulfur-oxygen, polysulfides, metallocyanide, and free cyanide species present in industrial processes, more specifically during gold leaching.…”

“…The spectra were obtained at 214 nm with a reference at 372 nm. Peaks: 0, peak of the system; 10, OCN -[18] (Reproduced with permission from Wiley-VCH).…”

Determination of free cyanide and zinc cyanide complex by capillary electrophoresis

“…To optimize leaching conditions, it is crucial to accurately monitor free cyanide and metallo‐cyanides at various stages of the cyanidation circuit. Speciation of metallo‐cyanide complexes has been reported using various methods such as anion‐exchange chromatography 2, 3, capillary electrophoresis 1, 4–6 and ion‐interaction chromatography 7–9. Capillary electrophoresis (CE) remains an appealing choice due to its high separation efficiency and short analysis time 10.…”

“…Several literature studies cover the use of CE for the separation and detection of metallo‐cyanide complexes 1, 4, 6, 11. However, to the best of our knowledge, none of the existing CE protocols succeeded at the separation and quantification of the zinc cyanide complex $({\rm{Zn}}({\rm{CN}})_4^{2 - } )$ 1, 5, 6, 11. Additionally, silver nitrate titration is largely used in industrial plants as a method for the quantification of free cyanide (CN − ).…”