Sumatra Copper & Gold has started shrink stoping at Belinau underground mine, which is part of Its Tembang Gold Project in South Sumatra, Indonesia. Shrink stoping is a highly selective mining method that minimises dilution and provides high value ore to the mill.
The process has commenced from Level 9 upwards.
A broken rock inventory will be built over coming months and drawn once the stope reaches the next level. The company plans to have four stopes operating by the end of the year and eight stopes operating simultaneously by the end of the March 2018 quarter.
In an announcement on September 6, Sumatra said decline development had advanced through Level 10 and was half way to Level 11 with all necessary dewatering infrastructure in place.
Two exploration drill drives will be established between Levels 11 and 12, which is the current base of planned development, to drill for depth extensions to the ore body. Two specialized diamond drill rigs have been ordered for this program.
Meantime, open pit mining at Berenai is progressing satisfactorily following the mud removal, although waste stripping is slightly behind schedule. Approximately 16,000 gold equivalent ounces is forecast to be mined from Belinau up to the June 2018 quarter.
Open pit preparatory work has started at Buluh, which is adjacent to the recently completed Siamang pit. This will be developed by year-end when waste movements from Berenai reduce.
Sumatra says the process plant continues to perform well, with the recent addition of air to the leach tanks resulting in gold recoveries of around 95% versus a budget of 91% and silver recoveries of 90% versus a budget of 77%.
The current production guidance of 30,000-40,000 gold equivalent ounces for 2017 was dependent on the commencement of stoping at Belinau. Sumatra now anticipates full year production to be at the lower end of this range with December quarter production expected to reach 10,000 gold equivalent ounces.
Production guidance for 2018 is anticipated to be 40,000-50,000 gold equivalent ounces.