BREAKING GROUND Blasting at Asanko’s new mine has facilitated the exposure of enough ore benches for mining to feed the mill at desired throughput rates
Developer, producer and supplier of commercial explosives AEL Mining Services has helped Canadian midtier gold miner Asanko Gold complete the first phase of the development of its new Obotan mine, in the Amansie West district of Ghana’s Ashanti region, a month ahead of schedule.
First gold was poured at the mine on January 26. AEL was awarded the explosives supply business by Asanko’s main mining contractor, PW Mining International, as breaking up the ground with blasts was imperative to enable faster digging rates.
Two benches and a ramp were blasted. Hole depths averaged at 4.2 m for the bottom bench and holes for the ramp ranged from 2.1 m to 8.6 m. The top bench averaged 6 m. AEL charged 183 holes with 4.4 t of S100 bulk emulsion. The 35 000 banked cubic metre blasted area comprised soft transitional rock material and a powder factor of only 0.25 kg/m3 to 0.3 kg/m3 was used on a 5 m × 5.5 m staggered pattern in 115-mm- diameter holes.
The commissioning of the blasts was part of the development of the Nkran pit at the Oboton mine, which is continuing to operate at long-term steady-state levels. Asanko claims that, to date, more than 22-million tons of material has been removed from the pit and various ore benches have been exposed.
There are now enough working faces available in the pit to facilitate mining of the requisite quantities of ore at planned grades to feed the semiautonomous grinding and ball mills at the Obotan mine at designed throughput rates. Asanko reported in January that the mills are operating at a milling rate matching or exceeding designed throughputs of 8 300 t/d. In addition, both mills have also attained grinds that are in line with the plant design parameters.
AEL provides a full prime, load, tie and shoot service for Asanko from its new distribution site at the Obotan mine.
Phase 2 of the mine’s development – a ramp-up of operations to commercial production – is scheduled for completion in the second quarter of 2016.