Mr. John Mirko reports
ROKMASTER SOLVES METALLURGY AT REVEL RIDGE, ACHIEVES OVERALL GOLD RECOVERY OF 96.8%
Rokmaster Resources Corp. has developed a high-recovery extraction process for gold, silver and other metals for the first time in the history of the Revel Ridge project.
Rokmaster's recently concluded metallurgical test program assessed proven metal recovery technologies to refine and optimize the metallurgical responses of the Revel Ridge Main zone (RRMZ) refractory mineralization.
For more than two years, Rokmaster has undertaken numerous metallurgical tests to advance the flowsheet from an initial overall gold recovery of 74.3 per cent (Rokmaster news release, Sept. 30, 2020). Recent metallurgical test work and repeatable locked cycle tests (LCT) provided an updated flowsheet that is returning
overall gold recoveries at 96.8 per cent.
The new flowsheet parameters used to achieve these high levels of recovery are:
- The primary grind has been coarsened to a much more readily achievable P80 of approximately 150 microns from the historical approximately 30-micron P80.
- Bulk flotation of all sulphides recovers approximately 98.3 per cent of the gold to a bulk concentrate in approximately 45 per cent mass pull;
- Bulk concentrate regrind is now set at approximately 20- to 30-micron P80;
- Lead recovery to a lead concentrate has increased from 57 per cent to 75.7 per cent;
- Gold recovery to a lead concentrate is approximately 21.1 per cent;
- Zinc recovery to a zinc concentrate has increased from 51 per cent to 69.5 per cent;
- Approximately 3.6 per cent of the gold is recovered to the zinc concentrate.
- The pressure oxidation parameters have been determined. Minor regrinding after pressure oxidation and prior to leaching assisted in achieving a gold leach recovery before solution losses of 98 per cent.
John Mirko, president and chief executive officer of Rokmaster, stated:
"Rokmaster has defined an efficient process flowsheet that achieves significantly improved recoveries of all target metals and is the first of its kind for the Revel Ridge (formally the J&L property) project, since work first began on the RRMZ in 1912. The metallurgical developments by Canenco Consulting Corp., Base Metallurgical Laboratories Ltd. and SGS Canada Inc. (Lakefield) have advanced the flowsheet to provide a robust, repeatable gold extraction process that significantly derisks the Revel Ridge project. Getting to this transformative stage has taken an impressive amount of testing and commitment, and we would like to thank our metallurgists for continued perseverance and achieving such excellent results to unlock the potential value of the RRMZ. With high gold recovery and solved metallurgy, Rokmaster will now progress with additional metallurgical testing of other variable parts of the RRMZ, including the visible native gold areas, updating the recent PEA and engineering as it continues drilling for resource expansion on this rare world-class asset with significant resources and exploration upside, located in a top-tier safe location."
About refractory precious metal mineralization and treatment
Pressure oxidation (POX) is a robust process used to extract gold, copper, zinc and other metals from refractory mineralization that typically give low recoveries when directly leached. The most common refractory minerals are pyrite and arsenopyrite, which are sulphides that trap the gold within them such as which is present at Revel Ridge. The POX process utilizes the injection of oxygen into slurries at temperatures around 220 to 230 degrees C and elevated pressures around 440 psi, to oxidize and liberate the minerals from refractory matrix. This process has been used since 1985 when it was first put into commercial production at Homestake's McLaughlin mine in California. It has increased in use since that time.
POX was selected as the most feasible processing technology for Rokmasters' refractory precious metal mineralization due to it being the most robust proven technology with package plants now being able to be purchased and built, its relatively smaller footprint compared with other oxidative process, its ability to provide a path to achieve high gold recoveries with RRMZ mineralization when compared with other available technologies.
The current resource at Revel Ridge consists of:
- Measured and indicated: 6.73 million tonnes containing 1,357,800 ounces gold equivalent (AuEq) at 6.27 grams per tonne AuEq;
- Inferred: Six million tonnes containing 1,220,400 ounces AuEq at 6.33 g/t AuEq.
The technical information in this news release has been prepared in accordance with Canadian regulatory requirements has been reviewed and approved by Stacy Freudigmann, PEng, FAusIMM, and by Eric Titley, PGeo, who are independent of the company and who are qualified persons as set out in National Instrument 43-101 and are independent of Rokmaster.
Rokmaster controls a portfolio of three significant exploration and development projects, all of which are located in Southern British Columbia in regions of excellent infrastructure.
We seek Safe Harbor.
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