Northern Dynasty and the Pebble Partnership have undertaken metallurgical test work on core samples from the Pebble deposit since 2004. These include:
- multiple series of bench-scale flotation tests to identify optimum reagents, grind-size and flotation residence times;
- small scale pilot plant;
- lock-cycle tests to simulate material flows;
- comminution tests to assess grindability of mineralized rock; and
- analyzing secondary gold processing alternatives.
Results to date indicate that metallurgical recovery rates at Pebble for copper, gold and molybdenum are at levels expected for such deposits.