Due to continued depressed silver and gold prices, Golden Minerals suspended production at Velardeña on June 21, 2013. The property was put onto a care and maintenance program in order to conserve the asset until operating plans and silver and gold prices indicate a sustainable cash margin for operations.
Velardeña’s mining operations are exclusively underground operations where our team of experienced miners is extracting mineralized material from rich, high grade mineralized veins.
There are two principal phases of underground mining: development mining and production mining. Development mining is composed of excavation almost entirely in (low-value) waste rock in order to gain access to the mineralized veins. Production mining is the removal of the wanted high grade material from the underground mine leaving behind an open space known as a stope.
The primary method of mining employed is “Shrinkage Stope Mining” which has been the way for our people in Mexico for generations. Our advanced team of miners also employs “Cut and Fill” methods in certain areas of our mines thereby minimizing dilution of the mined material.
Shrinkage Stope Mining
Shrinkage Stope Mining is a generic term used in mining to describe the process of mining upwards from a lower to an elevated horizon, leaving broken rock in the excavation created. The broken rock acts as a working platform and assists to stabilize the excavation by supporting the walls.
The method is ideally suited for our veins where excavation for steeply dipping veins of considerable vertical height is needed.
In Shrinkage Stope Mining, mining proceeds from the bottom upwards, in horizontal slices (similar to cut and fill mining), with the broken ore being left in place for miners to work from. Because blasted rock takes up a greater volume than in situ rock (due to swell factor), some of the blasted mineralized material, approximately 30% to 40%, must be removed to provide working space for the next slice of mineralized material. Once the top of the stope is reached all the mineralized material is removed from the stope.
Cut and Fill Mining
In Cut and Fill mining, the mineralized material is removed in a series of horizontal drifting slices. When each slice is removed, the void is filled with waste material from the sides of the mineralized veins, and then the next slice of mineralized vein is mined.
Mining starts at the lower level and works upward. Cut and Fill mining is very flexible. Mining can be carried out in one part of the stope while the other part is being filled. It also allows miners to selectively mine mineralized material and waste with little dilution. By identifying waste, it can be left behind in the
stope as fill.