Outstanding Column Test Recoveries, up to 90% at Mankarga 5
Managing Director Richard Hyde commented on the metallurgical test work:
"The column test work recoveries of up to 90% supports the Company's heap leach starter project development approach for the Mankarga 5 Project.
"All the columns responded well to the test work, however the leach rate achieved for strongly oxidised ore exceeded expectations, with 75% gold recovered within the first week.
"Importantly, this ore type represents the bulk of the material processed in the early stages of the project, and the accelerated recoveries will significantly enhance project cash flow and reduce working capital requirements."
- Gold recoveries of up to 90% and averaging 86% in column test work.
- Gold recoveries from column test work confirm heap leach suitability of oxide ore at the Mankarga 5 deposit, Boulsa Gold Project, Burkina Faso.
- Rapid leach kinetics with strongly oxidised ore gold recoveries of 75% after 7 days.
- Gold recoveries for all ore types more than 50% after 7 days.
- Low to moderate cement addition of 5kg to 10kg per tonne.
- Low cyanide consumption of 0.2 - 0.4 kg/t NaCN.
- High percolation rates with low slumping.
- Very low Abrasion and Ball Mill Work Indices indicate that the wear rates and power consumption will be low to very low by industry standards.
Three column tests have been completed on oxide ore from the Mankarga 5 deposit. Test work was completed at ALS Global in Perth on oxide composites from four metallurgical drill core holes which were sited at various locations in the Mankarga 5 deposit. One column contained strongly oxidized ore (SOX) at 100% passing 12.5 mm crush at a cement dose of 10 kg/t. Two columns contained moderately oxidized ore type (MOX) at 100% passing 12.5 and 6.25 mm respectively at 5 kg/t cement addition. All columns behaved well, showed rapid leach kinetics, high percolation rates and low slumpage. Based on data obtained from the 14 coarse feed intermittent bottle roll, three column tests and industry experience cyanide (NaCN) consumption is expected to be in the order of 0.2 - 0.4 kg/t. Details regarding the column tests are summarized in Table 1 (link below).
A series of percolation and agglomeration tests were also carried out on the SOX and MOX samples in preparation for column leach testing. Table 2 in link below provides a summary of the results.
Based on this test work SOX sample requires more than 5kg/t of cement for adequate agglomeration whilst the MOX sample presented good characteristics at 5 kg/t. The 10 kg/t cement addition to the SOX material provided very good agglomerates and zero slump suggesting 10 kg/t is in excess of what would be required. All samples reported very high percolation rates after appropriate cement dosage.
Abrasion indices (Ai) and Ball Mill Work Indices (BWI) were determined for the MOX and fresh (FRS) samples. The MOX values can be expected to be higher than the SOX material whilst the FRS results higher than the other three ore types as the FRS composition has not been compromised by oxidation. These results are summarised in Table 3 in link below.
Both samples provided very low Abrasion and Ball Mill Work Indices. This suggests that the all ore types will be able to be processed with conventional heap leach processing using the 1.6Mtpa heap leach plant as part purchased by the Company in February this year. Test work shows that equipment wear rates and power consumption associated with processing will be low to very low by industry standards.
In July, the Company delivered positive results from a Scoping Study which demonstrated a low capital cost, high margin, heap leach starter project (ASX,TSXV: 29/7/14).
The Company is focussed on near-term production with its immediate attention on the Mankarga 5 deposit and existing nearby gold prospects. The Company aims to be a +50,000oz per annum gold producer by the end of 2015 via a low-cost heap leach starter project.
To view tables and figures, please visit:
About West African Resources Limited
West African Resources Limited (ASX:WAF) (CVE:WAF) is a gold-copper exploration company dedicated to creating shareholder value through the acquisition, exploration and development of resource projects in Burkina Faso, West Africa.
West African has a landholding of 6,370sq km and 200km of strike length of early Proterozoic Birimian greenstone belts, which are highly prospective for gold mineralisation.
West African Resources Limited