A second round of ore testing at Lotus Resources’ (ASX: LOT) Kayelekera uranium project in Malawi has provided further improvements on results from the first stage.
The test work used a combination of sensors and reduced crush sizes to increase the project’s grade by up to 100% compared to the feed material and also saw recoveries increase from 86% to 92%.
Testing of the bulk 500 kilogram run-of-mine product was done at a Perth-based commercial ore-sorting facility owned by Steinert Australia.
One sample used a combination of colour and density sensors while the second was tested with a finer crusher size between 10 millimetres and 30mm (compared to between 20mm and 60mm in the first stage) to test the impact of particle size on separation efficiency.
Each test produced a primary concentrate sample based on the colour sort; a middlings sample based on the density sort; and a final tailings sample.
Each sample was collected, weighed and prepared at the laboratory, before being submitted for chemical assay.
Lotus reported results which showed colour to be the most effective sorting criteria.
Coarser feed sample results indicated an upgrade ratio of 1.7 at recoveries of 86% or an upgrade ratio of 1.5 with 92% recovery, compared to the upgrade ratio of 1.6 and recoveries of 71% in the original testwork.
Testing of the finer sample showed higher recoveries up to 94% at 1.3 upgrade ratio could be achieved, however the quantity of fines generated by crushing to the finer size was substantial and adversely impacted the grade.
Lotus is currently undertaking additional testing on the finer sample material to see if it can be upgraded with more tradition techniques such as flotation, gravity and size separation.
Upgrading is ongoing, with results expected to be received in the coming months.
Lotus said the next phase of ore sorting test work would incorporate new samples from site including lower grade materials and other rock types treated at Kayelekera.
The results will be incorporated into a project feasibility study which is due to commence in September.