Update on phase I
Northern Vertex Mining Corp. has provided an update on phase I -- pilot plant, the first phase of a three-phase project development plan for the reactivation of the Moss mine gold-silver project located in Mohave county, Arizona, United States, with highlights as follows.
-- Construction 100% complete
-- Mining operations 100% complete
-- Mineralized material loaded onto leach pad 100% complete
-- Gold extraction commenced 4.5 months ahead of Preliminary Economic Assessment ("PEA") scheduled timeline
-- Initial gold extraction rates in line with PEA expectations, 61% after 40 days
-- Stripping has commenced and gold sales underway
-- Applications for Pilot Plant permitable tonnage increases underway
"We are extremely pleased with results to date of our Phase I - Pilot Plant operations. The Pilot Plant phase was an integral part of our strategic three-phase business plan as this allowed us the opportunity to prove - or disprove - PEA operational expectations with actual results in the field. It is, in essence, our 'proof of concept'," advised D. Whittington, President and CEO
Northern Vertex Mining Corp. "The intention was to test, evaluate, re-test and re-evaluate for optimal performance at every stage of the mining, processing, heap leaching and recovery operations. Pilot Plant technical operations experience to-date has supported and de-risked the project and has substantially validated the operational assumptions of the PEA. Indications are that we should be able to successfully move into Phase II operations with a higher degree of confidence."
Whittington continued, "I am also extremely pleased that we are over 4 months ahead of the schedule outlined in the PEA. The efforts and contributions from the team on the ground has been a large part of our success to date and much appreciation goes to our local contractors as well: Tri R Construction, FNF Construction and Arizona Drilling and Blasting and our Engineering, Procurement and Construction management contractor, CDM Smith. We continue to work in partnership with Patriot Gold and the local communities surrounding the historical Moss Mine to support community activities, support business in those communities and to foster open and transparent communications about our ongoing activities with all stakeholders. Risks still remain but this work has significantly de-risked this project going forward."
Phase I - Pilot Plant: Construction Completion of Pilot Plant
As outlined in earlier news releases, the Company chose to advance various construction activities in parallel. This shortened the time-lag between initial mining and gold extraction when compared to the timeline expectations outlined in the PEA. Construction, which commenced May 1, 2013, was completed by the end of July 2013. The infrastructure necessary for Pilot Plant operations, namely heap 90,000 mt of mineralized material, install a leaching system and recover the gold and silver from the leach solution with a carbon column adsorption system was accomplished in full compliance with the Arizona Dept. of Environmental Quality BADCT criteria (Best Available Demonstrated Control Technology criteria) included:
-- site preparation earthworks
-- haul road construction
-- experimental pit development
-- waste site development
-- securing of contractors for mining operations
-- securing of contractors for crushing, screening, agglomeration and heap stacking operations
-- crushing, screening, agglomeration pad construction
-- agglomeration facility construction
-- heap leach facility construction
-- pond (barren and pregnant) construction
-- solution storage area development
-- process plant construction
-- carbon column construction
-- assay lab construction (wet lab and fire assay)
-- construction and development of other related facilities (electrical generation / water supply)
All of the above activities are restricted to patented property.
Phase I - Pilot Plant: Mining Operations
Mining operations commenced at the beginning of June 2013 and 100% completion has now been achieved with 90,199 dmt of mineralized material now mined under the permissible Pilot Plant permit of approximately 90,000 mt. Mining operations are being performed through local contractors Tri-R Construction, headquartered in Bullhead City Arizona. Mining operations have provided significant information relating to the pit wall slope stability, geotechnical information, dilution, drilling and blasting and ANFO factors. Reconciliation of the grade expected from the PEA and actual mined grade is underway and will be reported on in due course.
Phase I - Pilot Plant: Crushing, Screening, Agglomerating and Conveying
Crushing, screening and agglomerating of the approximately 90,000mt for Phase I - Pilot Plant operations are being carried out by local contractors FNF Construction headquartered in Tempe, Arizona.
Due to the unavailability of a pilot scale high pressure rolls crusher (HPGR), the recommended fine crushing process adopted for the PEA, the Company incorporated a three stage crushing process using cone crushers crushing to a targeted 95% -1/4" as per the PEA recommendations.
To date, pilot operations have indicated the following:
The three stage cone crushers have been crushing to 98% -1/4" indicating the potential to utilize conventional cone crushing instead of the HPGR for Phase II operations.
The required physical characteristics of the pilot plant agglomerates have consistently been achieved in-field indicating the effectiveness of agglomeration being applied to Moss mineralization. In addition, in-field cement consumption is in line with the PEA recommendations of 4lbs/ton.
Phase I - Pilot Plant - Loading of Mineralized Material onto Leach Pads
Loading of agglomerated material on the heap leach pads commenced June 28, 2013 and 100% completion has been achieved under the permissible tonnage on the current Pilot Plant permit of approximately 90,000 mt. A total of 90,199 dmt of crushed and agglomerated mineralized material grading 1.404 gpt Au and 13.891 gpt Ag, have been loaded onto the leach pad.
The Company has tested three stacking height designs and has been able to raise the stack height from the original 27' height to 30' and then to 35' while still maintaining effective percolation of the leachate. This indicates the potential to increase the design height of the leach pad in Phase II thus allowing the Company the opportunity to further optimize leach pad design. Drip-Emitter patterns were also tested and evaluated for optimal performance in the leaching of the stacked material.
Phase I - Pilot Plant: Initial Metallurgical Extraction Results
Leaching activities commenced in mid-August 2013 and are now in full operation. As of September 30, 2013, initial metallurgical recoveries for the lower grade material initially placed onto the heap leach showed approximately 61% Au extraction after only 40 days which is generally in line with laboratory expectations as adjusted for lab/infield factors. Overall recovery rates of 75% for Au were used in the PEA and the Company is on track to achieve this gold recovery level. Metallurgical data will continue to be collected and analyzed, so as to optimize the Phase I - Pilot Plant Operations field-scale pilot system and provide field-scale data for scale-up design to the conceptual Phase II - Operations.
As a result of advancing construction activities in parallel, metallurgical extraction is being achieved approximately 4.5 months ahead of the projected timeline as outlined in the PEA.
Based on experience to date, in-field NaCN consumption at 0.5 lbs/ton is below laboratory column leach test expectations as outlined in the PEA.
Phase I - Pilot Plant: Gold Recovery
Onsite carbon columns have successfully recovered gold in line with expectations. The Company has now made three shipments to the offsite carbon stripping facility and more are anticipated now that the pilot plant carbon collection facility is in full swing. The technical aspects of the carbon column facility are working well and the extraction of gold is as expected. Gold recovery operations are advancing well ahead of PEA expectations thus allowing earlier revenue recognition.
Phase I - Pilot Plant: Sales
Gold sales to date from initial product shipment and carbon stripping amounted to US $365,826 based on 270.4 received oz Au and 588.6 received oz of Ag. These sales were based on a spot gold price of US$1326/oz Au, US$22.30/oz Ag and a payable of 98.5% (Au) and 96% (Ag). The two additional larger shipments made to date are at various stages of precious metal processing (stripping of carbon, pouring of dore bars and refining into gold bullion) and await analysis and final determination of precious metals content.
Due to increase in stacking heights of aggregate on the heap, additional capacity is now available within the Phase I constructed leach pad. The Company intends to place an additional 17,500 mt on the leach pad to conduct further metallurgical tests and continue to de-risk the projected metallurgical performance in Phase II operations. Permitting applications are now underway to increase the amount of the allowed tonnage for crushing, agglomerating and leaching under the current Phase I - Pilot Plant permissible tonnes. An amended exemption for the Air Quality Permit (affects allowable quantity for crushing operations) has been received from the Arizona Department of Environmental Quality. An application for an amendment to the Aquifer Protection Permit (affects allowable quantity of material to be leached) has also been submitted. Once received, leaching of the additional tonnage will commence.
The foregoing technical information contained in this news release has been approved by Mr. Joe Bardswich, P. Eng. General Manager Moss Project, and a Qualified Person ("QP") for the purpose of National Instrument 43-101 (Standards of Disclosure for Mineral Projects).