Altura Mining’s focus during the quarter was to complete the ramp-up of production and stabilise process throughput with the fines plant. As disclosed in the previous quarterly report, a full review of the tailings thickener was undertaken by the designers and vendors of the equipment. The review led to substantial modifications to the thickener to reduce the amount of slimes material reporting and to increase the overflow and underflow pipe and pumps. These changes resulted in an immediate improvement in output and product grade from the fines plant. Continued increases and stability in daily production volumes ultimately enabled the company to declare commercial production at the Altura Lithium project by mid-March 2019.
On 13 March 2019, the company formally declared commercial production from its 100% owned Altura lithium mine. The decision follows the delivery of significant increases in the lithium concentrate output and overall metal recovery from both the coarse (dense medium separation (DMS)) and fines (flotation) plants in the weeks preceding the declaration.
The declaration also considered industry benchmarks for commercial production markers, which included achieving sufficient output, recovery and consistency of product for the confirmation of commercial production.
In the March quarter, ore mined increased by 15% on the December quarter with 404 000 t mined. The opencast mining areas have now opened up to an area large enough to permit efficient load and haul activities. Mining targets were achieved for the quarter despite the time lost to severe tropical cyclone Veronica, which caused some disruption in late March and resulted in a loss of approximately 2750 t of production. The mined grade for the March quarter was positive with an average grade of 1.16% Li2O.
Production of concentrate through the quarter was boosted by the ramp up of the fines concentrate plant which was commissioned through December 2018. A 26% contribution of fines to overall concentrate in January rose to a 47% contribution in March with an overall 38% contribution for the quarter. Design expectations were for a 45 - 50% contribution of fines to the overall blend. Following fines plant commissioning in December it was noted that there were issues with the fines plant thickeners. Some modifications to achieve design requirements were carried out after consultation with suppliers Roytec. Fines production stepped up significantly following these modifications.
The process plant continued to produce consistent results and excellent product grade during the quarter. February production was 55% higher than January, and March production (with cyclone losses removed) would have seen a 29% improvement on February. The cyclone-related loss however resulted in March being marginally higher at 7% than February.
The crushing and screening throughput resulted in capacities below design levels with structural rectification works by supplier Weir/Trio Crushing. Despite the lower than forecast availability and performance of this crushing package, Altura has continued a programme of rectification which it is confident will remedy remaining performance issues in the next quarter. Additional crushed stocks were produced in the previous quarter utilising a mobile crushing plant and this has provided sufficient buffer stocks to remove any downstream risk. The quarterly performance of the crusher was in line with the previous quarter at 222 707 t crushed.
The high pressure grinds roller (HPGR) which feeds both coarse and fines circuits continued to perform well during the quarter. The HPGR is one of the more critical components of the processing plant and it continues to show excellent availability and throughput.
Coarse concentrate production from the DMS plant was consistent with the primary and secondary DMS continuing to demonstrate excellent reliability and throughput. Coarse concentrate production is somewhat governed by the performance of the fines plant, but modifications carried out in April (now complete) will partially decouple the coarse and fines circuits such that the DMS plants can be operated at higher throughputs without impacting the fines circuit.
Read the article online at: https://www.globalminingreview.com/finance-business/29042019/altura-shares-quarterly-activities-report/
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