BAYOMBONG, Nueva Vizcaya: OceanaGold miner has introduced a green technology to backfill tunnels and gaps created in their underground mining operation, and not leave void spaces underneath.
This will assure the backfill tunnels do not harm the environment when the mining firm leaves the area and its contract with the Philippine government expires.
David Way, OceanaGold Philippines Inc. (OGPI) operations general manager, said the technology of “paste backfill” is quite new and the first of its kind in the Philippines but has been done in a few countries although not exactly similar.
He explained the green paste backfill technology will prevent ground subsidence or gradual caving in and sinking of an area of land and other issues.
“When miners extract ore from underground using the old-fashioned way, tunnels create void spaces underneath which poses the threat of ground subsidence in the future, and we don’t want it to happen in Didipio,” Way said.
“This year, we have shifted from open pit to purely underground mining and this multi-million dollar-worth paste backfill plant will take center stage,” he added.
Since 2013, OGPI has been operating the Didipio Gold and Copper Mine in the mineral-rich upland town of Kasibu in Nueva Vizcaya, which will now also utilize mine tailings or slurry from the processing plant as a material to fill gaps or voids left when ore is extracted underground.
“Our filling material will be made up of sand-like ground rocks mixed with a special cement designed for the purpose and will completely harden in about 22 days after application,” Way said.
He said the plant that converts a wet slurry into a paste backfilling material is a long rolling flatbed designed to reduce the moisture content of mine tails disposed of by the gold-copper mill.
“Upon achieving the right moisture level, it will be mixed with cement and pumped back underground to fill gaps and access tunnels which are no longer in use,” Way explained.
He said the effective paste backfills will also help eliminate the problem on flooding of tunnels as this would close crevices where groundwater flows.
“Our commitment to responsible mining is consistent with this new technology which will prevent incidents of ground subsidence decades after these were closed. We are very sure that these incidents will not happen in Didipio,” Way added.