Sulfoarsenide complexes of gold in hydrothermal solutions in the formation of gold ore deposits (thermodynamic modeling)

Abstract

The necessity and importance of the characteriza tion of the geochemical role of arsenic in the hydro thermal transfer of gold became evident after the dis covery and development of large gold ore deposits of quartz, sulfide-quartz, and sulfide-streaky types with arsenopyrite-pyrite gold productive paragenesis in Russia (Natalka, Nezhdaninskoe, Pogromnoe, etc.) [1], America (e.g., Donlin Creek), and other regions. The significance of sulfide-arsenical ore systems is most pronounced in the genesis of gold deposits of the black shale formation [2].The concentrators of gold at the largest ore fields of this formation are close and fine crystalline aggre gates, as well as individual crystals of the association of arsenopyrite and pyrite (frequently arsenious). These deposits are characterized by a direct correlation of the contents of gold and arsenic in ores [3,4], as well as by the high gold content in fine needled arsenopyrite [5]. The gold in ore arsenopyrites occurs in metallic and structural forms [6]. The line of the Au/As ≈ 0.02 mass ratio in arsenious pyrites separates the areas of metal distribution in the form of Au 0 nanoparticles at higher ratios and the positions of Au + in the structure of the matrix of a concentrator mineral at lower ratios [7].The paragenesis of gold and iron sulfide arsenious phases is most probably caused by the consistent trans fer of Au and As within the sulfuric-arsenious (sul foarsenide) polynuclear complexes occurring in a hydrothermal solution in combination with the hydro sulfide complexes of gold described in [8]. The publi cations [2,9,10] contain data on the dissolution of metallic gold in the hydrosulfide hydrothermal phase of 200-300°C temperature at a pressure up to 1 kbar for the 1.13-12.3 pH range, in the presence of orpi ment As 2 S 3 . Study [11] assumed the formation of either solid solutions or intermetallides of Au and As by the interaction of gold and metallic arsenic at 300°C in chloride solutions (0.01 and 0.1 N HCl) under hydrogen pressure and considered the AuCl · AsH 3 complex in the consistent transfer of Au and As.The data of mineralogy and experiments represent ing the probability of the appearance of gold sulfoars enides in hydrothermal solutions stimulate studies of the conditions of their formation in various ratios to sulfide Au complexes by means of solving the inverse problems of physicochemical modeling (PCM) on the basis of the SELEKTOR software (SW). The present study aimed to reveal the likely composition of sul foarsenide complexes of gold using computer analysis of the experimental data by [2, 10] on the Au solubility in the presence of orpiment.The calculations used numerical correlation of the data of the experimental system by means of the min imization of the difference in the calculated parame ters by the SELEKTOR SW and the values obtained in the experiments over the entire set of initial data, on Abstract-The composition and conditions of the formation of gold sulfoarsenide complexes were studied by means of the solution of inverse ...

Authigenic gold formation in the cyanidation tailings of gold–arsenopyrite–quartz ore of Komsomolsk deposit (Kuznetski Alatau, Russia)

“…Residual sulfides continue to be oxidized in the tailings (3), and Au can accumulate in the pore solutions as hydroxo-complexes (Cl -concentration is not enough to form AuCl 0 ) and complexes with sulfur (hydrosulfide, thiosulfate, and sulfate complexes) and arsenic (4-6) (Vilor et al 2014;Dutova et al 2006). The redox potential and solution composition mainly regulate the formation of these species: AuHS 0 , AuOH 0 -Au(S 2 O 3 ) 2 3-, H 2 AuAsS 3 -Au(SO 3 ) --AuBr(OH) 3…”