Los Filos is a heap leach operation. The ore size is reduced at the crushing plant and then it is hauled to the valley where it is stacked on engineered pads. A chemical solution is sprayed onto the ore, which extracts and absorbs the gold as it trickles through the ore. To regulate seepage rate, agglomerate (cement) is mixed into the ore for optimal ore exposure to the solution. Ultimately, the solution is directed to the plant where the gold is precipitated out.
A previous system conveyed the ore from the crushing plant to the leach pads via a glory hole ore pass and an underground conveyor, through the hill. An agglomeration drum mixed in the agglomerate before final delivery to the leach pads.
The conveying system experienced material flow problems right from the start, especially during heavy rains. The sticky ore tended to plug up the ore pass. Geological instability ultimately collapsed the ore pass, putting the transport system out of service only four months into its operation.
Against this background M3 Engineering was tasked with developing an alternate conveying route quickly since all haulage was now by truck and expensive. The logical, most direct and economical path was over the same hill (rather than under). The path required a down-hill high angle conveyor. Thus, Dos Santos International was approached about their DSI sandwich belt high angle conveyor. Being the best solution, DSI was awarded the contract in March 2009 for a downhill system which was dubbed the DSI G.P.S. (Gently Pressed Sandwich) high angle conveyor.
Concerns with geological instability remained, especially along the path of the DSI G.P.S. Further geological scrutiny led to abandoning this path altogether, thus abandoning the DSI G.P.S. as well.
M3 was again tasked with developing an alternate conveying path. This time a conventional conveyor system was developed, following the already developed truck ramps. Dos Santos International again submitted its proposal for the project, now an overland conveyor system. The project was awarded to DSI May 19, 2009. Engineering is now well underway.
The DSI expertise proved particularly advantageous on this project. The original 10 conveyor flight system has been rationalized to only seven flights by amalgamating with horizontal curves. Additionally, the third conveyor flight is especially engineered to accomplish the agglomeration by mixing through five intermediate tripped transfers. The en route agglomeration, conceived by Goldcorp, results in substantial savings by eliminating the need for the additional agglomerating drum.
The overland conveying path is predominantly downhill. While this presents the normal controlled starting and stopping problems, it also presents great savings opportunities. The downhill flights are decisively regenerative. Additionally, the drive motors, now generators, will feed back power into the grid which powers the other mine equipment. These carefully engineered conveyors will be equipped with variable frequency drives to ensure operations at maximum efficiency. This is another example of DSI’s commitment to “green” conveying.
In 2008, Dos Santos International installed five of its acclaimed DSI snake sandwich belt conveyors to convey kimberlite (diamonds) for the DeBeer’s company. Although there have been several other notable installations since these, this current project has prompted DSI to say they’ve gone from diamonds to gold.
To learn more about Dos Santos International and its variety of other “green” projects, visit www.dossantosintl.com.