ILST Posts report of Metallurgical testing results from the bulk sample collected from the Van Deemen Project, Mohave County, Arizona. The report is summarized below.
A bulk sample of material was received from the Van Deeman project for metallurgical testing. Average gold and silver head grades of bulk sample were 0.039 ozAu/ton and 0.05 ozAg/ton. Bottle roll tests were conducted on the sample at various feed sizes (80%-1" to 80%-200M) to determine amenability to cyanidation treatment and sensitivity to feed size. Bottle roll tests were followed by column leach test at the indicated optimum heap leach feed size (80%-1").
Summary metallurgical results show that the Van Deeman bulk sample "VD-2" was amenable to simulated heap leach cyanidation treatment at an 80%-1" feed size. Column leach test gold recovery was 69.8% in 74 days of leaching and rinsing.
Gold recovery rate was moderate, and extending the leach cycle beyond 74 days may improve recovery slightly.
Column test cyanide consumption was high (2.34 lb NaCN/ton ore). Cyanide consumption should be substantially lower during commercial heap leaching. The lime addition of 2.5 lb/ton was sufficient for maintaining protective alkalinity throughout the leach cycle.
Bottle roll test gold leach rate data indicate that the Van Deeman sample as somewhat sensitive to feed size with respect to leach rate, within the range of coarse feed sizes tested (80%-1" to 80%-10M). The slower leach rates for the coarser feeds resulted in lower bottle roll recoveries. Given a longer leach cycle, however, it is expected that bottle roll test recoveries at all coarse feed sizes would have been similar. Based on this observation, a feed size of 80%-1" was choosen for the column leach test. A column leach test at a feed size coarser than 80%-1"would have required more material than was available. For this reason, feed sizes coarser than 1" were not considered.
When the sample was finely groound (80%-200M), the bottle roll test gold recovery was substantially higher (88.2%). Column test recovery by size fraction data also indicate that grinding would likely be required to maximize gold recovery.
The link to the complete report can be found here.
International Star Announces Update Test Results
ILST has received an update on the column leach tests now being run to test recovery rates over time from McClleland Laboratories, Inc, Reno, Nevada, from the bulk sample collected in December 2013 from the Van Deemen Project, Mohave County, Arizona. “After nineteen days, the column leach test of our Van Deemen bulk sample is progressing nicely.” says Howard Metzler, Vice President of Operations. “The leach test has extracted 0.026 ounces per ton gold from the 80% minus 1” sample. The Leach Rate Graph shows continued leaching by the cyanide leach tests. The test will continue until the leach rate of the gold levels out.”
International Star, Inc. is currently soliciting bids from qualified firms to provide archaeological and biological surveys of the Van Deemen project area. The purpose of these surveys is for inclusion in a Mining Plan of Operations under the rules of 43 CFR 3809 (and other sections, as applicable). Bids will be evaluated on factors including cost, available start date, and projected time required, with an emphasis on timely completion.
International Star Provides Initial Bulk Sample Results
WILTON, CT, February 26, 2014 (Marketwired via COMTEX) – International Star, Inc. (OTC Pink: ILST), is pleased to provide the recent bulk sample results.
ILST has received the initial Bottle Roll Tests from McClleland Laboratories, Inc, Reno, Nevada, from the bulk sample collected in December, 2013 from the Van Deemen Project, Mohave County, Arizona. Average Head assays were reported as 0.043 opt Au and 0.06 opt Ag. Five different size fractions were subjected to 96 hour cyanide leach Bottle Roll Tests. The gold recovery from the 96 hour Bottle Roll tests for the coarse fractions varied from a low of 59.5% for the 80% -1” fraction to 68.8% from the 80% -1/4” fraction with a recovery of 0.022 opt Au. Gold was continuing to leach in the coarser fractions at the end of the 96 hour tests indicating that a longer leach time would result in higher recovery rates.
“We are pleased to see the current results confirm the previous testing that was done on Van Deemen.” Says Howard Metzler, Vice President of Operations. “These results show that the leach rate was slow for everything except the 200M feed, and after 96 hours, additional gold was still being recovered. The final recovery from the 1” feed was 59.5%, but it looks like the recovery would be significantly higher if the leach cycle were extended beyond 96 hours. Based on these results, and given a sufficiently long leach cycle, I think we can expect a similar final recovery at any of the coarse feed sizes evaluated. When that’s the case, the economics generally favor the coarser feed size.”
A column test of 80% -1” material is now being run to test recovery rates over time and to establish a base line for further testing.