Seawater inrush assessment based on hydrochemical analysis enhanced by hierarchy clustering in an undersea goldmine pit, China

摘要

Seawater inrush is deadly to undersea mine and it is very important to accurately assess the connectivity between seawater and the mine pit. With Xinli gold mine area as a case study, following the analysis of geological setting, a detailed hydrogeological survey and sampling were conducted and conservative ions test of mine water samples was carried out in the laboratory. Furthermore, the physical significances of ion concentration and ion ratios, such as Cl~-, γSO_4~(2-)/γCl~- and γNa~+/γCl~-, were checked. The test data analysis, enhanced by the physical significance check and hierarchy clustering analysis, was used to assess the overlying seawater inrush into the mine pit. It was determined that the undersea rock masses in the Xinli mine area bear high-mineralization brine water. The ore-controlling fault gouge and a thin layer of clay in Quaternary block the seepage of overlying seawater into the undersea mine pit to a great extent. The mine water from surrounding rock of the northeast gopher drift is closer to seawater in hydrogeochemical features, which indicates that the connectivity between the northeast of footwall of the ore-controlling fault and seawater is relatively good and should be closely monitored in future production. The mine water from the southwest gopher drift and crosscuts is similar to the brine (salty) water in chemical features, drains the net reserves of brine (salty) water in bedrock fissures and will impose few impacts on production in the near future. This approach is feasible and cost-effective.