Management of Arsenic Trioxide Bearing Dust at Giant Mine,

The Giant Mine, located in Yellowknife, Northwest Territories, Canada has been operating as a gold mine since 1948. Giant has been primarily an underground operation which used roaster technology to remove of gold from refractory arsenopyrite ore. The roasting process produced arsenic trioxide bearing dust as a waste product. This dust was pneumatically conveyed into underground storage chambers at a rate of 10-13 tons per day at peak production. Fifty years of operation have resulted in approximately 265,000 tons of roaster dust stored in 15 underground chambers. When underground storage began in 1951, it was considered the best option at the time, based the occurrence of permafrost in the bedrock. The first chambers were purpose built for dust storage in areas thought to be dry and surrounded by permafrost. From the 1960’s through to the mid 1970’s dust was placed in mined out stopes rather than purpose built chambers, however, the stopes were still located in dry permafrost zones.