Heap leaching tested at Omahola
Australian uranium explorer Deep Yellow Limited through its local subsidiary, Reptile Uranium Namibia, has completed the initial metallurgical tests demonstrating potential for a heap leach operation at its flagship Omahola Project for the extraction of uranium.
The column leach test, conducted at Gecko Laboratories in Swakopmund, was on a composite of samples collected from seven diamond drill holes located across the Ongolo and MS7 alaskite deposits. The results of the leach test were compared against conventional laboratory bottle roll and beaker agitation leach tests which are used to determine theoretical maximum uranium extraction.
The results of the tests show that uranium recovery from the column leach process was approximately 80% after 7 days with low overall sulphuric acid consumption of 12.4 kg/t. For comparison, uranium extraction from glass beaker and bottle roll agitation techniques was on average 90% with sulphuric acid consumption of 59.5 kg/t.
In a statement, Deep Yellow said heap leach processing has the potential to reduce cut-off grade, with a corresponding increase in overall uranium extraction whilst reducing project capital and accelerating the likely development schedule at Omahola.
Heap leaching is usually used to extract uranium from low grade ore of which the uranium content is too low to be economically processed in a uranium mill. The leaching agent, alkaline, or sulphuric acid, is introduced on the top of the pile and percolates down until it reaches the liner below the pile where it is caught and pumped to a processing plant.
Deep Yellow’s Managing Director Greg Cochran said of the results: “We are pleased with this initial result which has demonstrated that heap leach is a realistic option for Omahola. We acknowledge that there is still much work to do, however, this gives us the confidence to plan a trade-off study to compare the options to see which process route delivers the best economic outcome. It is noteworthy to see the substantial increase in the resource base using a lower cut-off grade, which provides us with additional optionality around project development given the existing high grade areas of the resource.