5th Phase – The 3m by 3m pillars are unstable in the long term, but they allow for a 6-month period in which it is possible to work safely in the last phase of stoping, that is the extraction (cleaning) with small excavators of the finer material that accumulated on the floor (threshold) and has an appreciable amount of tungsten due to the friability of wolframite. The 5th Phase is monitored with visual evaluation of the pillars and measuring of convergence roof-ground to verify the safety conditions within the stope. When the cleaning work is complete, the stope is abandoned and access is prohibited.