- Mineralogical variability studies show that the composites tested achieved similar recoveries (i.e. both by weight and grades of niobium and tantalum) to the partially optimized rougher flotation process established during the previous phase 1 and 2 metallurgical programs.
- Over 90% of the composites tested achieved rougher recoveries which exceeded 96% tantalum and 92% niobium within the tantalum/niobium circuit only.
- The amount of tantalum and niobium metals reporting to the flotation feed is relatively constant at about 81.4% for tantalum and 80.6% for niobium
- The Mineral Resource update underway at AMEC will include results of exploration in 2012, as well as 34 drill holes (totalling 8,715 m) of infill drilling completed in 2011 and not included in the previous resource.
VANCOUVER, March 27, 2013 /PRNewswire/ - Commerce Resources Corp. (TSXv: CCE, FSE: D7H, OTCQX: CMRZF) (the "Company" or "Commerce") is pleased to provide a further update on recent work completed at its Blue River Project since release of the National Instrument (NI) 43-101 compliant Mineral Resource update (Commerce news release July 6, 2012) for the Upper Fir Deposit. Newly completed mineralogical variability studies show that the partially optimized flotation flow sheet which formed the base of the metallurgical analysis in the Preliminary Economic Assessment (Commerce news release November 3, 2011), and which was further optimized during Phase 2 test work (reported December 3, 3012) shows good applicability across the range of mineralogies tested.
The geological, engineering, metallurgical and environmental programs carried out in 2012 provide broad support to the advancement of exploration and development at the Company's wholly owned Blue River Project, east-central British Columbia. The new metallurgical results continue to strengthen the foundation of broadly based technical knowledge developed in 2012, and after completion of the mineral resource update currently in progress by independent consultants AMEC Americas Ltd. ("AMEC"), will be sufficient to support the initiation of a pre-feasibility study (PFS).
"We are pleased with these new results from what has been a significant amount of work accomplished in the past year. These metallurgical results provide additional upside to the positive test work previously reported in the PEA, a major milestone in our progress to develop the Upper Fir. The post-PEA metallurgical results reinforce Commerce's belief that we are in the process of building a very important long-term source of conflict free and ethical tantalum which could potentially supply 10% of the current world's market for the long term." says Dave Hodge, Commerce's President. "We will be extremely interested in the upcoming resource update from AMEC which will be based on all work to date."The Blue River Property is host to the Upper Fir Tantalum and Niobium Deposit, which was discovered in 2002 and which has been the focus of the Company's activities since 2005. In fiscal 2012 Commerce spent approximately $3.8M on the Property. Metallurgical Test Work in 2012 Metallurgical work in 2012 has continued to update and optimize the process flow sheet described in the NI 43-101 compliant Preliminary Economic Assessment ("PEA") study completed by AMEC on the Blue River Project (effective date of September 29, 2011; see Commerce news release of November 3, 2011). The process flow sheet for the recovery of the tantalum and niobium described in the PEA was developed in 2011 based on Phase 1 studies. In April 2012, Commerce commissioned Acme Metallurgical Ltd ("Acme Met") of Vancouver, BC to initiate a Phase 2 investigation. This was designed to follow-up the successful results of the earlier program which had tested flotation as the preferred method to remove the larger portion of fine slimes and carbonatite minerals early in the process. Subsequent process steps could then focus on material containing Ta and Nb. Phase 2 testing optimized the use of desliming and carbonate rejection flotation, as well as chemical reagent dosages to increase the efficiency of rougher/cleaner Ta/Nb flotation. This work enabled finalization of the process flow sheet developed in Phase 1 which was based on composite samples BS-2F and BS 2G. All Phase 2 work was conducted on these same composites and all tests were conducted at a grind size of 80% passing 130 microns. These results were reported in a news release dated the 3 rd of December 2012. Mineralogical Variability Testing A total of 767 samples of drill core rejects from the Upper Fir deposit were combined into thirty-six composites (selected to represent five different end member mineralogies within the deposit) and subjected to flotation testing. This variability testing, initiated in April 2012 and completed in January 2013, had the primary objective of determining the composites' response to the partially optimized flotation procedure established during the Phase 1 and 2 metallurgical programs completed in 2011 and 2012 and previously reported. Key Areas of Variability Investigation and Results: Desliming and Mass Rejection
- The majority of the composites are amenable to the standard one stage cyclone desliming process with rejection of 17.2% of the weight as slimes, containing 7.2% of the tantalum and 6.9% of the niobium. Variation of the weight rejected is minimal between composites with no significant effect from grind sizes or mineralogy.
- The total carbonate mass rejection is proportional to the amount of carbonate and phosphate materials in the feed, with the average weight of carbonate concentrate floated and rejected for all composites being 53.2% of the mass, with losses of 11.4% for tantalum and 12.5% of niobium. Metals losses were directly proportional to the weight of concentrate removed and independent of head grades.
- Cleaning of the carbonate concentrate was not performed during this testing campaign, however, the scavenger stage of flotation represented about 40% of the total weight floated, containing about two thirds of the metal losses. This is indicative of mechanical losses due to strong scavenging action and entrainment.
- It is strongly recommended that cleaning of the concentrate be kept in the flow sheet to reduce these losses. Recycling the cleaner tails to the Ta:Nb flotation feed might account for 2% to 6% of the metals in the feed.
- Though the weight of material left after slimes and carbonate removal does vary with the type of mineralogy, it overall averages 29.5%. The amount of metals reporting to Ta:Nb flotation nevertheless remains fairly constant at about 81.4% for tantalum and 80.6% for niobium. Losses of metals to that point are proportional to the weights removed and thus statistically inversely proportional to head grades.
- Within the Ta:Nb rougher and cleaner flotation circuit only, over 90% of the composites achieved rougher grade Ta:Nb recoveries which exceeded 96% for Ta and 92% for Nb.
- The final stage of magnetic separation also increased the final concentrate grade with minimal loss of the Ta and Nb minerals. This supports results from Phase 2 work in which approximately 50% of the final concentrate mass was removed with minimal Ta/Nb loss.
- The carbonate flotation stage appears to require a lower dosage of the oleic acid collector as tantalum and niobium minerals are likely trapped and entrained with the tight froth generated by the over dosage of oleic acid.
- The balance of flotation reagents diamine acetate (Duomac T- as collector) and fluosilicic acid (H 2SiF 6 as pH modifier/silicates depressant) in the Ta:Nb cleaning circuit should be investigated as metals losses are mostly observed between pH 4 to 3.
- A fifth and sixth stage of cleaning should be investigated to achieve a grade of 35% combined Nb-Ta oxides.
- Locked cycle tests should be completed to provide clear indication of reagents consumption as each stage.
- Full assaying of final concentrate products, particularly for sulphur and rock-forming elements, could provide additional information which would help orient further investigations.
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