Study On The Mode Of Au And As In Low-Temperature Hydrothermal Solution Based On Geochemical Model

The forms of chemical elements in ore-forming fluids have always been a matter of great concern in the field of earth science.In recent years,with the continuous development of the geological industry,research has gradually established a relatively rich on the ore-forming fluid thermodynamics and kinetics of the ore-forming fluid in the field of geological science database.These databases through the data modeling method to simulate the geological process to provide a strong support for researchers.With the continuous development of computer technology,through the computer to establish the corresponding geochemical model,and then simulate the geochemical reaction of the method has been gradually established,and in the field of geochemistry has been widely used.Based on the continuous titration model and the partial equilibrium model in the geochemical model,establishing the corresponding geochemical model and using the Geochemist's Workbench software to study the forms of Au and As in the low temperature hydrothermal system by adjusting the variables,such as temperature,ion concentration,oxygen fugacity,sulfur fume,pH and Eh in low-temperature hydrothermal fluids.The results show that Au is mainly in the form of solid gold(nanoscale natural gold),AuCl2-and AuCl4-in the range of 0 ~ 300 ?,and is favorable for the formation of AuCl2-and AuCl4-in oxygen-enriched state.The formation of AuCl2-is inhibited by temperature,and the formation of AuCl2-is enhanced by the increase of the temperature.The formation of AuCl4-is enhanced by the increase of the concentration of chloride ions in the low pH state.The low pH state and the increase of the concentration of chloride ions inhibit the formation of AuCl2-.The solid gold form is mainly affected by chloride ion concentration,the higher the chloride ion concentration,the more easily converted to AuCl2-and AuCl4-.When lg aCl->-3.6,the solid gold begins to convert to AuCl2-and AuCl4-.As is mainly present in the form of H3AsO4,H2AsO4-,HAsO42-,AsO43-,As(OH)4-,AsO2OH2-,As(OH)3,orpiment and realgar.As the temperature rises,H3AsO4 and As2S2 disappear,producing white arsenic minerals,As mainly exists in the form of H2AsO4-,HAs O42-,AsO43-,As(OH)4-,AsO2OH2-,As(OH)3,orpiment and claudetite.Acid conditions is conducive to the formation of H3AsO4 and H2AsO4-.Under alkaline conditions is conducive to the formation of HAsO42-and AsO43-.