Metallurgy

Additional metallurgical testing incorporated into the PFS resulted in average gold recovery rates of approximately 83% on crushed and agglomerated material, an improvement from the recovery rate of 80% identified in the PEA. The Relief Canyon ore deposit contains an oxidized and partially oxidized gold mineral resources and reserves that metallurgical testing and historical mining experience indicate are amenable to cyanide heap-leach processing. In 2015 and 2016, Pershing Gold conducted metallurgical test work on drill core and bulk samples to confirm heap-leach processing on additional resources and reserves that have been identified within the existing pit. The metallurgical test work was based on identifying three distinct zones on cross-section identified as the Main, Lower, and Jasperoid zones.

Results from column leach testing demonstrate that the major Relief Canyon ore types (limestone breccia, clay matrix breccia, and jasperoid) contained in the Main Zone, as well as the Jasperoid and Lower Zones, generally would be amenable to heap-leach cyanidation treatment.

The column-leach and permeability tests indicate that agglomeration is required in order to achieve hydraulic conductivity and a corresponding gold recovery on a consistent basis. There is also evidence that blending of low and high fines content material will aid hydraulic conductivity.

The planned processing method is heap-leach cyanidation of primary crushed ore (80% passing three inch) that has been agglomerated using eight pounds per ton of cement as a binder.