JOHANNESBURG (miningweekly.com) – An extensive underground drilling programme over the last six months at North River Resources’ Namib lead zinc mine, in Namibia, has increased the project’s Joint Ore Reserve Committee-compliant mineral resource estimate 36% to 1.25-million tons.

Within this, indicated resources had increased 33% to 877 000 t, at 2.7% lead, 6% zinc and 44.4 g/t sulphide minerals. 

The programme also increased the average zinc grade by 13% and the average lead grade by 4%.

North River Resources MD Martin French said the group had invested considerable expertise and focus into its resource expansion programme and currently had three drills operating underground.

“This is particularly challenging, as the mineralised shoots at Namib are erratic, making them difficult to define. Targeting involved complex work delineating a strata-bound envelope and integrating this with a reinterpretation electromagnetic data to direct our drills.

“We are, therefore, especially pleased that these efforts have borne fruit, with such a significant increase in total resource, a strong conversion to indicated resource and a good increase in grade,” he commented.

French added that the resource expansion programme was continuing apace, with the start of drilling from its new exploration tunnel, 150 m below the Northern lodes. 

The miner recently invited a number of engineering firms to tender for an engineering, procurement and construction management contract for the turnkey construction of a processing plant.

Site preparation, meanwhile, continued with the installation of surface and underground communications.

Offices had been built on site, road upgrades were in progress, along with the installation of additional underground infrastructure and safety systems.

“We hope to be adding further resource and reserves over the coming 12 months,” the company said, noting that work continued to complete the feasibility study and other aspects of implementation planning, in anticipation of a mining licence approval.

North River expected to release the results of a feasibility study in October.