Yilgarn South

Overview

The Western Australian Darlot, Granny Smith and Lawlers gold mines comprise the Yilgarn South region for reporting purposes. In 2011, Yilgarn South produced 314,000 ounces of gold at total cash costs of $720 per ounce. Barrick Gold Corporation owns 100% interest in the mines.

The Darlot gold mine is a trackless underground operation located on the Yandal Greenstone Belt, approximately 680 kilometres northeast of Perth, Western Australia.

The Granny Smith underground gold mine is located 950 kilometres northeast of Perth and 23 kilometres south of Laverton in the state of Western Australia.

The Lawlers mine is an underground operation located on the Norseman/Wiluna Greenstone Belt, approximately 660 kilometres northeast of Perth, Western Australia. 

In 2011, Yilgarn South produced 372,000 ounces of gold at total cash costs of $692 per ounce.  At the end of 2011 proven and probable reserves were estimated at 1.41 million ounces gold.

Location

The Granny Smith undergroundgold mine is located 950 kilometres northeast of Perth and 23 kilometres south of Laverton in the state of Western Australia.

The Lawlers mine is an underground operation located on the Norseman/Wiluna Greenstone Belt, approximately 120 kilometres northwest of Leonora in Western Australia.

The Darlot underground mine is located 110 kilometers north of Leonora.

Geology & Mineralization

Darlot:
The deposit is hosted in an Archean succession of mostly intrusive and extrusive mafic rocks and occurs within a corridor of NNW trending structures. The property covers an extensive goldfield discovered more than 100 years ago. The Darlot orebody is a shear-hosted, gold-mineralised, quartz vein system about 1.5 km long. The structure is continuous along strike with mineralisation open down dip indicating potential for depth extensions. The Centenary orebody is a large, structurally controlled, quartz vein hosted gold deposit. The lode, which extends for more than 1.2 km, varies from 5 m to more than 50 m in thickness.

Granny Smith:
Gold mineralization is associated with a shear zone. The sediments and granodiorite which host the mineralization are bleached and silicified and contain extensive veining consisting of carbonate, quartz, pyrite, sericite and gold. Mineralization is continuous along a 11,400 foot strike length with several areas of higher grade material amenable to open pit mining. Mineable ore occurs in three deposits: the Granny, Goanna and the Windich. Most of the mineralized zone is strongly weathered with relatively soft saprolite and oxidized rock layers overlying the harder, fresh rock. Mineralization remains open to the south.

Lawlers:
Gold ore is derived from two distinct geological domains - a western sedimentary domain (New Holland) and an eastern mafic/ultramafic volcanic domain (Fairyland). The western area deposits are high grade ladder quartz veins within sandstones enclosed in finer sediments. Mineralized structures extend to depth and have been traced over a strike length of over 5 km

As of December 2011, proven and probable reserves were estimated at:

- Lawlers: 1.5 Mt at 4.76 g/t gold for 417 koz contained gold;

- Granny Smith: 3.63 Mt at 5.34 g/t gold for 635 koz contained gold;

- Darlot: 2.52 Mt at 4.32 g/t gold for 357 koz gold, for a total of 1.409 koz gold.

A 2011 exploration program identified new mineralization and the company considers that there is potential for mining expansion at Granny Smith below the current underground mine.

Mining & Operation

Darlot Mine:
Modern mining, including development of the Darlot Pit, commenced in 1988. The Pit was completed in 1995 and the mine is now an entirely underground operation based on both the original Darlot orebody and the new Centenary orebody. It is a trackless mining operation.Underground access is by three interconnecting declines from the Darlot pit. Mining is by long hole open stoping with cemented backfill.

Granny Smith:
Mined a total of 12 open pits over its mine life and nowaday it is doing underground mining. As of of 2011 it has been in operation for 21 years and produced 6 million ounces gold over that period of time.

Lawlers:
It is an open pit & underground mining operation. 

In 2011 production at Yilgarn South increased by 18% over 2010 due to better average head grades at Lawlers, improved production rates at Darlot and higher tons mined and processed at Granny Smith, primarily as a result of the mine expansion.

Processing

Granny Smith processing plant consists of two-stage fresh ore crushing circuit with closed circuit screening and a single-stage oxide ore crushing circuit, a semi-autogenous grinding mill in closed circuit with a cone crusher, an agitation leaching and carbon-in-pulp circuit, tailings gravity retreatment plant with fine grind, a gold recovery plant with carbon reactivation, and a tailing thickener.

Ore is conventionally crushed, ground in a SAG mill/ball mill circuit and leached using a CIP process, followed by electrowinning and smelting to produce gold dore. A tailing retreatment plant enhances gold recovery by 1% to 11% depending on ore type. Power is provided by a diesel generating system. Plant capacity averages around 11,500 tonnes per day, depending on the oxide/fresh ore blend.

At the Lawlers mine sulphide and oxide ores are treated at the on-site mill.

At Darlot mine ore is treated by conventional carbon-in-leach at the on-site mill. The plant has a capacity of 800,000 tonnes per year.

Environment & Community

Granny Smith gold mine aims to have a positive impact on the local area by supporting local children and communities. It also supports services such as the Flying Doctor and the fire and emergency services.

Barrickt also works hard to protect the environment - one of their initiatives is running a 200 cattle station to help maintain the equilibrium of the land.