MINDORO RESOURCES LTD.: EXCELLENT METALLURGICAL TEST RESULTS FROM KAY TANDA
Mindoro Resources Ltd. has obtained high gold recoveries in a third round of metallurgical tests of large-diameter, drill-core composites from both oxide and mixed (transitional) oxide, and sulphide mineralized material from the Kay Tanda gold-silver prospect, Philippines. The results to date indicate that both composites are highly amenable to heap leaching. It appears that most of the gold occurs in the cracks and fissures in the rocks and is readily accessible to the cyanide solution. Gold dissolution is rapid and high gold recoveries have been obtained from both composites, and with low cyanide consumption.
Kay Tanda is being evaluated for its open-pit, heap-leach potential. Preliminary bottle-roll metallurgical testwork on reverse circulation cuttings was largely positive (reported in Stockwatch on Jan. 14, 2004). A second round of testing was carried out on a small bulk sample of oxidized mineralized material from a pit and gave excellent results (reported in Stockwatch on Dec. 2, 2005). The current test had the objective of evaluating heap-leach characteristics of near-surface oxide mineralization, as well as deeper mixed oxide/sulphide (transition) mineralization. Samples were collected by large-diameter (PQ) core drilling and submitted to Metcon Laboratories in Australia. The program was designed and supervised by an independent consultant, Peter J. Lewis and Associates, of Australia.
Two series of testwork were completed on the two composites. The first test was a bottle-roll test on composites at 80 per cent passing a sieve at 75 micrometres. This test is required to indicate the maximum gold and silver recoveries obtainable and to compare these with the recoveries obtained by heap-leach testing. Very high gold and silver recoveries were obtained from both types of mineralized material. From the oxide material, 93.4 per cent of the contained gold and 83.7 per cent of the contained silver were leached and recovered in 48 hours. From the transition material (mixed oxide and sulphides), 88.6 per cent of the gold and 87 per cent of the contained silver were leached. These are unusually high recoveries, especially for the sulphide-containing material.
For the second round of testing, column tests (heap-leach tests) were performed on a crush size of minus 12.7 millimetres, that is, one-half inch, which is close to the lower size limit normally used for heap leaching. Gold recovery from the oxide material after 29 days of leaching was 80.3 per cent. Gold recovery from the transition material after 23 days was 80.6 per cent. Silver recoveries are awaited. Both composites are highly amenable to heap leaching.
Because of the encouraging results, a further test was commenced at a very coarse crush size of 50 mm (two inches), since the coarser the crush, the lower the processing costs. This work is in progress and results will be reported on completion. Since the transition sample contained a high proportion of sulphide-related mineralization and leached very well, a test will also be carried out on deeper, entirely sulphide-related gold and silver mineralization as well.
Mindoro management is most encouraged by the results from Kay Tanda to date and considers them a strong basis for further evaluation of the project's economic potential. Preliminary work on a National Instrument 43-101 resource estimate has commenced to be followed by a scoping study.
The program is carried out under the supervision of J.A. Climie, PGeol, president of Mindoro and a qualified person as defined by National Policy 43-101. Metallurgical reports will be posted on Mindoro's website on completion of all testwork.