Alluvial formations are considered to be the gold deposits that have been exploited most throughout history. Several deposits have been mined since the start of the 20th century in Colombia, with the alluvial deposit in the valley of the Nechí River being the most important. It is located in the Lower Cauca region of Antioquia, which is exactly where we carry out our operations.
HOW IS IT DONE?
The most suitable mining system for extracting gold from deep alluvial deposits is using bucket dredgers, with the cut and fill method. Gold extraction is carried out through gravity concentration on board a dredger and with constant environmental recovery that involves joint production processes with the local community.
We carry out alluvial operations at MINEROS S.A. using a production unit, which consists of a suction dredger, a bucket dredger and heavy machinery equipment.
1. Suction dredger:
Extracts the soil (vegetation layer) until approximately the first 18 meters of depth, and it pumps it to the surface to form hydraulic backfills. This first extraction does not normally contain gold.
2. Bucket dredger:
Extracts gravel, clay and sand with gold content from 18 to 27 meters deep approximately. These are extracted inside the dredger through gravity processes of weight and size, without using mercury or any contaminating chemical agent. Unusable material is used for tailings and hydraulic backfills, where new ecosystems will be reestablished.