Technology
The EDM technology division patented a product and technique to alleviate some of the issues that underground mines face when backfilling.
Extracting gold or other precious minerals involves a very small fraction of valuable minerals, resulting the bulk of the waste materials at the ground level for disposal. In addition, the ore removal leaves very large underground voids.
These voids have to be backfilled before proceeding with excavation of nearby orebodies. Backfilling the voids ensures regional stability, minimizes ore dilution, provides a working floor, controls subsidence and facilitates subsequent excavation and ore removal nearby.
In addition, there are environmental regulations requiring that the mine site is left in good condition on the completion of mining operation, with all underground voids backfilled, all waste materials disposed in a responsible manner and the flora and fauna in the region are protected. By sending the waste tailings to where they came from, the large underground voids are backfilled while the tailings are also disposed effectively in an environmentally friendly way.
About this Process
The product that EDM has developed and rolled out at the most prominent mines in South Africa, achieves that optimal balance of solidity and flow. They optimized filling the empty stopes with maximum density, minimum excess water and virtually eliminated the risk of range (pipeline) blockages. The net effect of the lower water content is a substantial saving on the binder (cement mix) cost, which means that the solution has a zero-cost effect for the mine.
When paste fill is poured into the stope, a plug consisting of paste fill with high cement content is formed at the base before the rest of the stope is filled often continuously. When the wet slurry of tailings is placed within the empty stope, it is necessary to barricade the access drives to isolate the rest of the working environment in the mine. Failure of the barricades can lead to inrush of tailings into the other areas of the mine, causing economic damage and sometimes fatalities. The high usage of cement in these processes come at an exorbitant expense, high carbon footprints and at a substantial cost of time whilst waiting for the fill to dry sufficiently to enable nearby blasting and mining in a safe way. The developed product also assists in this regard by creating greater stability at a much faster rate with a lower carbon footprint and using less cement.
The model the group has used in South Africa is to do an in-depth study at the target mine to determine if there is an economic benefit to be derived by changing over to their product. Once this has been demonstrated to the entity the team assists in implementation and training in the new process. Their income source and interest are in providing the product over the long-term.
