MEDUSA Mining continues underground development at the Co-O Gold Project in northeast Mindanao. During the September quarter, 6371 metres were developed – up from 5671 metres the previous quarter – with 3697 metres of this being horizontal development, and the remainder vertical.
The focus continued to be Levels 7, 8 and 9 to open up new stoping blocks on the high-grade GH vein, with development also continuing on Level 10. Overall, material hoisted for the quarter was 142,799 tonnes (DMT) of ore and waste combined.
The quarter saw winding ropes changed out in the Level 8 shaft as well as other general shaft maintenance. Major winder maintenance was planned for the December quarter. Completion of the Level 8 pump station has controlled the dewatering such that shaft flooding is now rare.
At the Agsao Inclined Shaft a breakdown of pumps on Level 5 resulted in flooding of Level 5 reducing the availability of the Agsao and Baguio shafts. With completion of the Level 8 pump station, the flooding was restricted to Level 5. Work has been carried out to allow the 5 level pumps to operate more reliably and effectively.
The 29E and 12E Winzes continue to hoist material from Level 9 and Level 10 to Level 8. The 43E Winze had reached the Level 9 by 30 September, and all three winzes have been linked together by development on Level 9. Development of the 43E Winze is continuing to Level 10.
The 48E Winze has also reached Level 9, continuing onto Level 10. The 35E Winze winder chamber is complete, with a sinking winder being set up to continue development of this winze.
For the quarter, there was 674 metres of horizontal development and 255 metres of vertical development on Levels 9 and 10. Stoping activities continued on Level 9. The E15 Service Shaft has progressed to Level 8 – a total of 378 metres from the shaft collar. The final design depth to level 10 is 512 metres.
There was an improvement in production and all-in-sustaining-costs. The operation produced 24986 ounces at an average head grade of 6.59 g/t, compared to 23846 ounces in the June quarter. AISC was US$973 per ounce, an improvement on the US$1180 per ounce in June quarter.