MODELLING MELTS IN HYDROTHERMAL SYSTEMS-THE LIQUID BISMUTH COLLECTOR MODEL

摘要: The Liquid Bismuth Collector Model (LBCM) was first outlined by Douglas et al.(2000). In this model Au is concentrated from undersaturated solutions by Bi melt. The system comprising an aqueous fluid and a Bi-Au binary melt is important because its study represents the first step in further understanding Bi rich polymetallic melts in hydrothermal environments. Bi-Te systems are prime candidates for deeper study and have shown even greater potential as scavengers of Au than Bi melts alone.Bi has a low melting point (271.4 C) and the Au-Bi system has a eutectic temperature of 241.1 C. Bi also has a negative dP/dT relationship between solid and liquid phases resulting in melting point depression of 7.6 C per kbar increase in pressure. Thus Bi is a crucial component of polymetallic melts because it has a potentially large effect in keeping these systems molten down to low temperatures. It also makes the Bi-Au-fluid system within reach of laboratory studies without excessive technical difficulties. Therefore, we are also developing an experimental setup to test the results of this modelling study.