Despite a reduction in grade to 6.86 carats per 100 cubic metres, which Lucapa said was a result of adjusting the mining dilution factor, the mine’s in-situ resource now sits at 135,900 carats at a modelled average diamond value of $1,440/carat. This was up from the previous estimation of 100,700 carats at $1,620/carat.
The updated resource accounts for mining depletion to the end of December 2020, as well as the delineation of new or additional resources. It’s also a result of Lucapa’s improved knowledge of existing resource areas, such as Leziria, which has delivered good quality stones.
The miner noted there was now around two million cubic metres of gravel available, which should support Lulo mining at current rates until 2026.
Lucapa says around 112,000 carats have been recovered from Lulo over the past six years, generating $200 million in sales, using an average price of $1790/carat.
The firm has a 40% stake in Lulo, which hosts the world’s highest dollar-per-carat alluvial diamonds. The rest is held by Angola’s national diamond company (Endiama) and Rosas & Petalas, a private entity.
The resource upgrade comes only a day after Lucapa announced it had completed a plan to boost production at its Mothae mine in Lesotho by 45% to 1.6Mtpa.
The company said the processing plant was handed back to the production team after finishing the installation of a new scrubber bypass conveyor, a primary jaw crusher and other associated upgrades.
The upgraded processing plant is being re-commissioned and ramped up to its new increased capacity, it said.
Lucapa noted that Mothae will complete this ramp up by the end of this month and will then operate at the newly expanded capacity from the second quarter of the year onwards.