The total was 18% higher than the month prior, when it mined 339,000t.
The March tonnage was made up of 364,100t that graded 5.52% copper from the Kakula mine, including 100,000t grading 8.70% copper from its high-grade centre. Kanoko, which also makes up the complex, reported 36,000t at a grading of 3.78% copper.
The complex's pre-production surface stockpiles now have about 2.56Mt of high-grade and medium-grade ore that have an estimated blended average of 4.60% copper.
"Kamoa-Kakula is on track to substantially exceed the 3Mt of high-grade and medium-grade stockpiled ore, holding more than 125,000 tonnes of contained copper, that the 2020 pre-feasibility study projected would be stockpiled prior to the planned start of processing in July 2021," the company said.
Ivanhoe also reported that its underground mining development is ahead of schedule; its first phase, which involves a 3.8Mt/y mining and milling operation, is now 92% complete. Crews remain on schedule for July for first production from the concentrator plant, which now is undergoing commissioning activities.
Its Phase 2 expansion is also making progress toward a 3Q22 start-up at 7.6 Mt/y, and engineering will then commence for a Phase 3 expansion to 11.4Mt/y.
Mine development at Kamoa-Kakula is now at more than 3,100 metres, bringing its total underground development to approximately 38.6 kilometres, or about 13.5km ahead of schedule.
"The outstanding mining rate in March was driven by improved crew efficiencies and a higher percentage of ore coming from drift-and-fill stoping operations," CEO Mark Farren said.
"We are comfortable with the mining performance as we move into final commissioning of the Phase 1…concentrator plant. If we consistently mine at around 400,000 tonnes per month, we will continue to add to the surface stockpiles ahead of our Phase 2…concentrator plant commissioning."
He said the company will be continuing to monitor mining rates to ensure a balance of new mining crews added to its underground operations against its surface ore stockpile totals as it works toward its commissioning of Phase 2.
"The large surface ore stockpiles will give us considerable flexibility during the ramp up of Phase 2 production," he added.
