Forge - September 2009

Yamana goes for gold

Fazenda Brasileiro, an underground gold mine belonging to Yamana Gold Inc., has been using Maptek Vulcan™ software since 1997.

The mine is situated in the Barrocas municipality, Bahia, about 200 km from Salvador, Brazil. Currently, all the geological modelling and mine plans for excavation are carried out with Vulcan.

Once the indicated resource has been defined, access ramps are designed using development tools in Vulcan’s underground menu, with a 5.0 m x 5.5 m drive dimension and 15% gradient.

The inclination of the ramp follows the direction of the orebody, and maintains a 15 m buffer distance from the host rock. Where the geometry of the orebody undulates, the ramp design can be adjusted easily to suit equipment specifications and the dimension of drives.

Resource definition is carried out by interpreting mineralised contacts within the orebody. The access ramp to the cross-cuts is designed in a longitudinal direction, so that when it intersects the orebody, development mining will be more productive, mining ore instead of waste.

Sub-levels are developed every 15 m until the ore drives are established to commence production mining, which involves drilling and blasting.

The orebody is very irregular and discontinuous, often described as large scale ‘pockets’. The mining method uses sub-level stoping between ore drives.

The mine is intensely mechanised, applying international best practice operational and work safety standards to underground mining. Work at the mine is scheduled in 3 shifts of 8 hours a day, 7 days a week, and 360 days a year, with uninterrupted changeover.

Drilling on the declines and cross-cuts is accomplished with twin-boom jumbo rigs. ANFO explosive is detonated by a non-electrical retardation system. All drilling is planned using Vulcan’s Ring Design tools, allowing fast projection and plotting, and providing a report with all the information necessary for its execution. Drilling in the stopes is carried out in fan patterns, designed in Vulcan.

Mucking out the drawpoint and transporting the material to the shaft is carried out by 10 t LHDs and articulated off-road 30 t trucks. In the stopes, the LHDs are operated by remote control. The transported material is hoisted up to the surface via the shaft. The shaft is 5.5 m in diameter and 400 m deep. There are two 13 t skips, with cable guidelines and 1000 HP frictional tow-car.

Re-evaluation of the mining parameters and procedure is undertaken alongside drill & blast and extraction. The dilution and recovery data is calculated by comparing what was designed against what was accomplished; information is obtained from the wireframe shapes. A retrospective analysis of the projects in Vulcan aims to establish parameters for reconciliation.

Using Vulcan in the Fazenda Brasileiro operation simplifies the processes of indicated resource calculation, mine design, and drill & blast design. The fast and accurate methods allow the Fazenda Brasileiro team more time to spend on analysing their plans.

Thanks to
Fabio Ferreira de Oliveira
Mine Planning
Yamana Gold