This article presents case of the small scale trial excavation utilizing adapted backfilling mining method. Focus herein is on mining method itself and excavation technology.
Underground mine is already developed to the depth of 100m where excavation will take place. Average copper grade is 1.3%, ore body morphology is lens-like or irregular. Rock mass is weak, limiting stable span of the stope to 3m and striped pillar of 4m is required between adjacent stopes. Purpose of the trial excavation is to expand knowledge of the underground conditions and determine possibilities for improvements of resource recovery.
In order to perform trial excavation, small portion of the total ore body is selected for method and technology testing. Initial plan is to provide ~8500t per month in duration of approximately one year of production in the trial excavation. Around 180.000t is total reserves in the trial excavation block.
Figure 1 Shape of total ore body
Figure 2 Detailed overview of ore body portion selected for trial excavation
Mine is already operational and level L+1600m from where trial excavation is meant to start has been already developed. Some existing underground openings will be actively used during trial excavation in order to service and communication between stopes.
Figure 3 Main development openings for trial excavation
Underground mine is opened with inclined shaft that connects all levels that are active up to date. This will be main mine entrance for the trial excavation. Since it is equipped with winch hoisting system, these underground openings will be main hoisting openings.
Level L+1600m has connection with the inclined shaft and significant portion of underground openings already exist and some of those will be used as main development for the trial excavation. From the connection with inclined shaft to the trial stopes there will be main transportation route for ore haulage with draw point at the inclined shaft.