Intrepid?s PEA completes with excellent gold recoveries at E. Java project

Australian firm Intrepid Mines Limited said on Tuesday that the previously advised column leach test work program for the preliminary economic assessment (PEA) has been completed with excellent gold recoveries from the near surface gold-silver oxide deposit at the Tumpangpitu Prospect, Tujuh Bukit gold project in East Java.

?These positive results warrant detailed investigation into heap leach-only economics compared to a milling circuit. This oxide deposit lies above the deeper and significantly larger main copper-gold porphyry resource,? the company said.

The gold-silver oxide metallurgical test work was completed at Kappes Cassiday in Reno, Nevada (KCA) and included coarse, fine and milled bottle roll leach tests, agglomeration and percolation test work, compacted permeability test work and column leach tests.

A total of eight separate column leach tests were completed using material from each of the four separate composites (three oxide, one transition ore with head grades of 0.42 to 0.54 g/t gold). The composites were stage crushed to minus 25 millimetres and 9.5 millimetres and leached over 82 days.

Gold extraction for the minus 25mm crush across all zones averaged 88% in completely oxidised material and 75% in the transition zone, similar to earlier results from a grinding mill flowsheet. Improved gold recovery was noted with minus 9.5mm crush material.

Silver extraction for a 25mm crush across all zones averaged 22% in completely oxidised material (29% at minus 9.5mm) and 36% in transition (64% at minus 9.5mm). These are lower recoveries than from a grinding mill flowsheet, however, it is anticipated the lower extraction levels will be offset by significantly lower capital and operating costs, particularly lower power demand. Test work confirmed high percolation rates for stacked heaps.

With the addition of assay results from 31 new drill holes, independent consultants Hellman and Schofield Pty Ltd have provided an updated resource for the gold-silver oxide deposit resource of 130 million tonnes (MT) at 0.55 grams-per-tonne (g/t) gold (Au) and 18 g/t silver (Ag). The entire resource is classified in the Inferred category. This updated estimate, reported in accordance with the JORC Code and National Instrument 43-101, represents a total of 2.4 million ounces of contained gold and 80 million ounces of contained silver.

The company believes that a heap leach scenario provides an attractive option for economic extraction, consequently the previous practice of reporting resources at a 0.5 g/t higher cost grinding mill scenario and lower metal price assumptions) will This cut-off grade is based upon an open-pit mining scenario followed by price of US$1000 per ounce and a silver price of US$20 per ounce. (kanti)