Independent metallurgical tests are painting a brighter picture at the Rapu Rapu polymetallic project in the Philippines for
Signet Engineering of Australia has shown that the Ungay Malabago volcanogenic massive sulphide deposit is amenable to conventional flotation processing techniques, and that separate copper and zinc concentrates can be produced, along with acceptable amounts of pyrite. Based on this, total processing costs have been recalculated at US$10.41 per tonne — 31% less than previous estimates.
Ungay Malabago is the larger of two nearby deposits at Rapu Rapu, hosting 3.5 million tonnes grading 1.75% copper and 2.75% zinc, plus 3.42 grams gold and 43.3 grams silver per tonne. The other, Hixbar, hosts an estimated 1.36 million tonnes grading 1.25% copper, 1.25% zinc, 2.96 grams gold and 15.5 grams silver, though work there has been sidelined in favour of advancing Ungay Malabago.
“The Ungay Malabago prospect has shown the most potential,” says TVI spokesman Cyrus Ameli.
Last fall, Austalian-based Lafayette Mining became operator of the project and began a 3,000-metre drill program to provide metallurgical samples, confirm previous drill results and test for mineralized extensions. The company heads up a group that can earn a 75% interest in the property from TVI by spending US$3 million on exploration over three years and paying US$150,000 in cash.
The front-end of the flowsheet produced two bulk concentrates of 20% and 25% copper. Most of the gold and silver reported to this stage of the float, with overall recovery rates ranging from 80% to 90% for copper; 60% to 75% for gold; 70% to 85% for silver; and 10% to 15% for zinc.
Arsenic levels topped 0.7%, with no other potentially penalizing elements detected. The arsenic is reportedly much lower in concentration than was suggested by previous tests and thus significantly boosts the marketability of the concentrate.
Tests on zinc metallurgy are continuing, as the recent investigation indicates that appreciable levels are remaining in the copper stage of the float. However, the metal is reported to be readily recoverable and operators believe that a concentrate consisting of 51-54% zinc will be produced. This is expected to liberate 75-85% of the zinc, 5-20% of the gold and 3-15% of the silver.
Signet used core samples from both new and old holes, representing a composite of the entire deposit. Previous tests were limited to samples from one hole only and were focused primarily on the upper zone of mineralization.
Meanwhile, results from 13 holes, totalling 1,976 metres, have been released. All intersected mineralization, with those collared at the western end of the deposit showing an increase in gold and zinc grades in that direction, possibly as a result of remobilization along a fault.
Highlights include:
- hole 20, which hit 19 metres (from 128 to 147 metres) averaging 1.57% copper, 2.48% zinc, 9.31 grams gold and 64.93 grams silver;
- hole 21, which cut 31 metres (131-161 metres) grading 2.46% copper, 3.85% zinc, 5.27 grams gold and 66.98 grams silver;
- hole 22, which intersected 67 metres (71-138 metres) of 1.72% copper, 2.8% zinc, 2.47 grams gold and 35.71 grams silver; and
- hole 25, which returned 22 metres (156-178 metres) of 2.09% copper, 4.17% zinc, 4.26 grams gold and 47.39 grams silver.
Also, two stepout holes show that mineralization continues along strike to the west. Hole 28 intersected 8 metres (152-160 metres) grading 1.7% copper, 2.84% zinc, 2.89 grams gold and 25.45 grams silver, whereas hole 29 hit 4 metres (146-150 metres) grading 1.47% copper, 4.4% zinc, 1.52 grams gold and 15.25 grams silver.
The remainder of the program will attempt to extend mineralization farther to the west and downdip. The resource will then be updated.
Mineralization at Ungay Malabago has been outlined over a continuous strike length of 800 metres, along which it averages 50 metres in width and extends from surface to a vertical depth of 150 metres. It remains open downdip, along strike to the west and, in places, to the north and south.
Lafayette has received a Certificate of Clearance from the National Commission of Indigenous Peoples, allowing it to acquire a mining licence for claims covering the Ungay Malabago deposit and adjacent ground to the west. Those western claims include the Hixbar deposit.
As well, the company has retained environmental consultants to begin baseline studies in preparation for obtaining an environmental compliance certificate.
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