Bullfrog Gold Corp. (OTCQB:BFGC)(“BFGC”or the “Company”) is pleased to announce new exploration targets with related claim staking, increased gold recoveries from leach tests and the submittal of an environmental permit application at its Bullfrog Project (Project). The Company controls the commanding land and resource positions in the Bullfrog mine area, which is 120 miles NW of Las Vegas and 4 miles west of Beatty, Nevada.
This Project is situated in one of the most exciting gold exploration areas in North America, as evidenced by significant drilling activity during the past few years and Coeur Mining’s US $90 million acquisition on August 2, 2018 of Northern Empire Resources, a company whose NW land boundary is 2 miles east of Project lands. In 2017 AngloGold Ashanti acquired a land position 4 miles east of the Project and recently staked 227 claims adjacent to BFGC’s land position. Corvus Gold continues to explore its North Bullfrog and Mother Lode Projects in the Beatty area and recently staked several additional claims 2.5 miles east of BFGC’s land position.
New Exploration Targets & Claim Staking
East Exploration Targets
The Company has evaluated several thousand surface samples collected throughout the Bullfrog area and identified three new exploration targets that have similar host rocks and structures as the 2-million ounce Bullfrog deposit. These targets are one mile east of the Bullfrog Pit and contain gold on the surface up to 1 g/t, thereby documenting that a gold bearing system(s) is present in these target areas. These targets are in a corridor approximately 500 meters wide and 1,700 meters along strike that contains no interior drilling. The six closest holes to the east are in the footwall and the six closest holes to the west are in the hanging wall of structures that may possibly contain significant mineralization. Six additional mining claims were recently staked to cover the southern part of this prospective mineral zone.
Deep Exploration Targets
In addition to expanding resources in the Bullfrog and Montgomery-Shoshone pits and surrounding areas, further study of the 155 miles of drill data has identified several deep targets. Four holes averaging 2,000 feet deep were drilled in the bottom of the Bullfrog pit during 1996 and intersected multi-gram gold mineralization in the pre-Cambrian meta sedimentary rocks. These meta-sediments host several deposits a few miles east and west of the Bullfrog area and are pervasive at depth on Company controlled lands. As a result, 17 additional mining claims were recently staked adjacent to the Company’s land position, which now totals 4,790 acres. Six holes previously drilled on these new claims intersected significant mineralization in this deep host zone.
Metallurgical Testing
In early 2018 the Company collected 1,800 pounds of sample from two random locations in the north Bullfrog pit for initial scoping tests at McClelland Laboratories of Reno, Nevada using high pressure grinding rolls (HPGR’s). HPGR’s as the third stage of size reduction produce many more micro-fractures and a much finer size than conventional cone crushers, thereby increasing and accelerating gold and silver recoveries. However, test data revealed that this initial bulk sample represents a brecciated vein ore type that comprises less than 10% of Project resources, rather than the upper and lower stockworks that represent more than 90% of Project resources.
Notwithstanding, the HPGR column test recovered much more gold than the conventionally crushed sample of this brecciated vein ore type. Subject to additional sampling and testing, a HPGR leach feed is anticipated to further increase the 75.9% gold recovery achieved from coarser, cone-crushed stockwork mineralization that was tested in 1994. In this regard, the stockwork mineralization is composed of brittle rhyolite and silica welded tuff units that were fracture filled with mineralization and are therefore particularly receptive to improved leaching from a fine, multi-fractured HPGR product.
Bottle Roll Leach Tests
Gold and silver recoveries from the HPGR bottle roll test sized at -1.7 mm or -1/8” were respectively 11.2% and 20.5% greater than the coarser simulated cone crushed test sized at 9.5 mm or -3/8”. A third bottle roll test recovered 87% on a split of this sample sized at 0.15 mm (or -100 mesh) to compare with the 26 million tonnes milled at this same size during 1989-1999 and the test completed on the brecciated ore type in 1994. All bottle roll tests were leached for 96 hours.
Bottle Roll Tests
| Feed | Au | gAu/mt ore | Ag | gAg/mt ore | Reagents kg/mt | ||||||||||||||||||||||||
| Crush | Size, | Rec. | Calc. | Head | Rec. | Calc | Head | NaCN | Lime | ||||||||||||||||||||
| Type | mm | % | Extract. | Tail | Head | Assay | % | Extract. | Tail | Head | Assay | Cons. | Added | ||||||||||||||||
| Cone | 80% -9.5 | 58.8 | 0.47 | 0.33 | 0.80 | 0.97 | 11.1 | 0.2 | 1.6 | 1.8 | 2.3 | <0.07 | 0.8 | ||||||||||||||||
| HPGR | 80% -1.7 | 70.0 | 0.63 | 0.27 | 0.90 | 0.97 | 31.6 | 0.6 | 1.3 | 1.9 | 2.3 | 0.10 | 1.3 | ||||||||||||||||
| HPGR Improvement | +11.2 | +20.5 | |||||||||||||||||||||||||||
| Cone | 87% -0.15 | 89.0 | 0.89 | 0.11 | 1.00 | 0.97 | 55 | 1.1 | 0.9 | 2 | 2.3 | <0.07 | 2.0 | ||||||||||||||||
Column Leach Tests
Leach tests were then performed on splits of the same 2018 composites using columns that were 5-7/8 inches in diameter and filled to approximately 9 feet high with 70 to 76 kg of sample. Both columns were leached for 51 days with 33 intermittent days of resting. Remarkably, respective HPGR gold and silver recoveries were 19.2% and 14.7% greater than the simulated coarser cone crushed column test. For reference, the sample weights placed in the columns were 70 to 76 times greater than the customary 1 kg sample weights used in the bottle rolls. As expected from previous operations and tests, all bottle roll and column tests had very low reagent requirements.
Column Leach Tests
| Feed | Au | Gold g/mt ore | Ag | Silver g/mt ore | NaCN | Lime | ||||||||
| Crush | Size, | Rec. | Calc. | Avg Hd | Rec. | Calc. | Avg Hd | Cons, | Added, | |||||
| Type | mm | % | Extract | Tail | Head | Assay | % | Extract | Tail | Head | Assay | kg/mt | kg/mt | |
| Cone | 80%-9.5 | 58.2 | 0.46 | 0.33 | 0.79 | 0.88 | 9.1 | 0.2 | 2.0 | 2.2 | 2.0 | 0.78 | 0.6 | |
| HPGR | 80%-1.7 | 77.4 | 0.65 | 0.19 | 0.84 | 0.88 | 23.8 | 0.5 | 1.6 | 2.1 | 2.0 | 0.78 | 1.0 | |
| HPGR Improvement | +19.2 | +14.7 | ||||||||||||
Discussion and Analysis of Test Programs
Column leach tests completed in 1994 achieved a gold recovery of 75.9% on 40 kg of representative stockworks averaging 0.99 g/t that were conventionally crushed to -3/8”. An 800-ton pilot heap leach test in …read more
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