Testwork on unoxidised mineralisation has shown flotation gold and silver recoveries of about 90% can be achieved with mass pulls of about 10% to 15%. Evaluation of further processing of flotation concentrates for recovery of gold and silver is ongoing.
Test data indicates that the oxide and transitional mineralisation from both the DeLamar and Florida Mountain deposits behaves similarly and is amenable to processing by low-cost heap leach cyanidation methods. On Florida Mountain material, column leach test cyanide consumptions were generally less than 1.3kg sodium cyanide per tonne and resulted in over 71% of the gold being recovered within 10 days.
"These results clearly demonstrate that heap leaching is a viable option for a large percentage of the recently updated resource at the DeLamar project … with testwork indicating heap leach recoveries as high as 85% for gold and up to 50% for silver," said president and CEO George Salamis.
About 54% of DeLamar's measured and indicated resource tonnage are hosted within oxide and transitional mineralisation that will be modelled for heap leach processing in the upcoming PEA due in September.
The 46% unoxidised mineralised material will be modelled for milling and flotation processing. Testwork has demonstrated that upgrading this material by gravity and flotation processing sees over 90% of the gold and silver reporting to a sulphide concentrate which will require further processing such as fine grinding and leaching or oxidative treatment such as autoclaving.
DeLamar produced gold and silver from 1977 to 1992 using agitated cyanide leaching followed by precipitation with zinc dust and in-house refining of the precipitate to produce silver-gold doré. Recoveries of oxide, transitional and some portions of the unoxidised mineralisation at the property achieved average recoveries of 96.2% for gold and 79.5% for silver in the first 15 years of mining operations. Integra testwork shows there are other processing options than agitated leaching.
DeLamar hosts a measured and indicated resource of 119.6 million tonnes grading 0.41 grams per tonne of gold and 25.1g/t of silver for 1.6 million ounces of gold and 96.2Moz of silver. It also hosts an inferred resource of 21.3Mt grading 0.39g/t of gold and 15.2g/t of silver.
Shares of Integra Resources (TSXV:ITR) are trading at C93¢, valuing the company at $72 million. Its share price has increased 7% so far this year.