JOHANNESBURG (miningweekly.com) – Gold explorer B2Gold has announced a “significantly” higher grade updated gold mineral resource estimate for the Wolfshag zone, located directly adjacent to the east and north-east of the company's new 90%-owned openpit Otjikoto mine, in Namibia.

The updated inferred mineral resource contained 675 000 oz of gold within 2.581-million tons, grading 8.14 g/t of gold using a 3 g/t cutoff.

This inferred resource was below a pit shell, containing an additional 1.03-million tons, grading at 2.81 g/t gold, or 93 000 oz of gold, in the indicated category.

The previously released initial inferred resource estimate for the Wolfshag zone was 6.8-million tonnes, grading at 3.2 g/t gold, containing 703 000 oz of gold.

Engineering studies were currently under way to determine which portion of Wolfshag could be mined using the openpit mining method and which portion could be mined through underground mining. Openpit mining was due to start in 2016.

The company said in a statement that the conceptual plan would be to blend higher-grade material from Wolfshag with ore from the Otjikoto pit, resulting in an increase in yearly gold production at Otjikoto and improved project economics.

The primary Otjikoto openpit deposit was 29.4-million tons at a grade of 1.42 g/t of gold, containing 1.34-million ounces of gold.

“In 2015, Otjikoto is expected to produce between 140 000 oz and 150 000 oz of gold at a cash operating cost of between $500/oz and $525/oz and all-in sustaining costs of about $700/oz.

“Once the planned mill expansion is completed in the third quarter of 2015, increasing the yearly throughput at the mill from 2.5-million tons a year to 3-million tons a year, the company expects yearly gold output to increase to 200 000 oz in 2016 and 2017,” B2Gold noted.

The company planned to complete an updated mine plan by the end of 2015, which would further evaluate the use of openpit and underground mining at Wolfshag.

Meanwhile, detailed metallurgical testwork was completed in 2014 on drill samples from the northern portion of the Wolfshag zone using the Otjikoto feasibility study optimised comminution, gravity and leach conditions.

These conditions were used as the design basis for the Otjikoto process plant circuit.

Gold recoveries for the master and variability composites ranged from 94.9% to 97.8%, with overall master composite recoveries of 97.2%.