Testing, performed by Steinert US at the Walton, Kentucky facility, using its multisensory sorting system, included samples of run-of-mine material totaling 73kg and 128kg of a composite sample. Preparation and analysis of the samples was completed by SGS Laboratories in Lakefield, Ontario, Canada.
In preparation for testing of the ROM and composite samples, the fines of -10mm were removed by screening, leaving a ROM and composite test samples range of -50mm to +10m. During ROM material testing, it was upgraded from a feed grade of 14.7g/t to 20.3g/t, with 92.8% gold recovery and 32.7% waste rejection.
Composite material was upgraded, too, from a feed grade of 25.4g/t to 43.2g/t, with 81.3% recovery and 52.1% waste rejection.
Braveheart officials said the purpose of testing was to determine whether the Steinert ore sorting system and methodology could be used to upgrade Alpine's mineralised material prior to trucking and processing. The Steinert machine uses a combination of X-ray sensors and laser technology.
"The X-ray transmission targets the atomic density of the material and measures the X-ray attenuation of each particle which has a direct correlation on the mineral composition of the rock," CEO Ian Berzins said. "This allows higher-density material to be separated from lower-density material. The former contains more of the mineralised rock and the latter is separated as low-grade or waste. The laser sensor targets the shape and brightness of a particle.
He called the results "very encouraging" and indicative that Alpine's mineralised material will be an important component to the operator's overall beneficiation process.
Alpine, according to historical records from the BC Ministry of Mines and Energy, has achieved a plant feed grade of 22g/t Au using some hand sorting of mineralised material. The mine's current NI 43-101 report reflects 268,000t at an average 16.5g/t Au.
"Ore sorting at the mine site has the potential of up-grading the mineralised material to historical levels using this technology," Berzins said. "Braveheart is currently investigating several options for custom milling of Alpine mine mineralised material in reasonable proximity to the mine. By upgrading the value of the ore at the mine trucking and processing costs can be significantly reduced on a unit basis."
Braveheart will be commencing its 2018 exploration program at Alpine by mid-August.
The Alpine property is part of the Big Strike gold-silver property located west of the West Kootenay mining district.