お知らせ • Jan 20
Orion Minerals Limited Announces Early Production Assessment for Prieska to Be Fast Tracked
Orion Minerals Limited advised that it has commenced workstreams to assess the merits of phasing the development of its Prieska Copper-Zinc Project in the Northern Cape Province of South Africa (Prieska Project), in a manner that brings forward the start of production and allows for dewatering of the underground workings to commence ahead of the final investment decision for the full-scale project construction as planned in the 2020 Bankable Feasibility Study (BFS-20). The BFS-20 outlines the plan to re-establish the Prieska Copper Mine, which was previously operated as an underground mine between 1971 to 1991. During this time, mine records show, 46Mt were mined to produce 430kt of copper and 1.01Mt of zinc in concentrates. While funding discussions for the Prieska Project, based on the BFS-20 plan, are in progress with banks and finance institutions, investigations into further enhancing the technical and commercial aspects of the Project are being advanced. The company’s strategy is to capitalise on the positive near-term base metals market and focus on investigating opportunities that have the potential to bring forward the start of production and revenue generation, potentially reducing the upfront external peak funding requirements of the project. On this basis, the Company's senior management team has focused on the following plan and opportunity assessment (Early Production Scenario), comprising: re-planning for upfront mining of the open pit (already included in the BFS-20 plan to occur at the end of the mine schedule); assessment of the remnant pillars remaining from historical mining operations for potential opportunistic early extraction; and preparation of a plan to commence the dewatering of the underground workings using a modular configuration, with the first modules being commissioned in calendar year 2022, ahead of the scale up to the full-scale pumping rate proposed in the BFS-20 plan. The scenario that is being investigated is based on and maintains the core elements and material assumptions of the Prieska Deeps BFS-20 plan. The work to fully evaluate and quantify this opportunity are expected to be completed by mid-2022. A feasibility level study is underway to assess the merits of bringing forward the open pit mining.Extraction of the shallow supergene sulphide ore by open pit mining is included in the BFS-20 plan. It is currently scheduled to be undertaken from Year 13 of the mine life, with tonnage milled stepping down from the 200,000 tonnes per month rate of the earlier underground mining to 100,000 tonnes per month, using only one of two installed mills for the open pit3 mining phase. The 1.12 Mt of supergene sulphide open pit ore, at an average grade of 1.9% Cu and 2.4% Zn, is planned to be mined and processed over a 2-year period in the BFS-20. The Early Production Scenario plan will assess the impact of re-scheduling mining of the open pit to the start of the Prieska Project mine plan to allow concentrate production with earlier commissioning of the first mill, while the second mill is being installed and other long-lead time capital projects for commencement of the Prieska Deeps Mine are completed. In the BFS-20, the start of production is planned for month 33. Rescheduling of open pit mining to commence early aims to assess the impact of open pit production occurring concurrently to the long lead time elements of the Deeps Projects, such as mine dewatering, shaft refurbishment, underground infrastructure construction and stope preparation, which are all independent of open pit mining. A small high-priority underground drilling program on the +105 open pit will commence shortly to provide sample density sufficient to upgrade the Mineral Resource classification in accordance with JORC Code (2012) reporting guidelines. This program, consisting of 770m of underground diamond drilling, will also supplement geotechnical information and confirm the survey plan location and widths of the voids. The program is scheduled to commence in February 2022 with completion anticipated by June 2022 and updated Mineral Resource and Ore Reserve estimates available shortly thereafter. The Early Production Scenario plan is currently evaluating whether the sulphide ore processing plant can be commissioned by month 19, approximately 14 months ahead of the original BFS-20 schedule. As with the BFS-20, the processing plant would treat open pit material at a reduced throughput compared to steady-state operations for the Deeps, using one of the two mills that have already been secured in preparation for full-scale production from the Prieska Deeps. In this scenario, the second mill, together with additional flotation concentrators, would likely be installed later, as part of a phased expansion to accommodate feed from mining of the Deeps at the increased throughput rate. The opportunity to place almost all tailings from the ore processing plant as back-fill in historic andplanned mining voids, hence reducing the size of the required, lined, tailings storage facility and thereby further reducing upfront capital outlay and funding is also being assessed. Remnant pillar evaluation: Mine records, plans and recent investigations by the Company confirm that previous underground mining was undertaken using long-hole open-stoping methods, without the use of any form of backfilling to stabilise the remaining voids. A grid of pillars was left in place to provide geotechnical mine stability. This resulted in inefficiently low ore extraction ratios at the time. Mineralisation and geology were reported to be continuous across the mined stopes and the remaining pillars. Mine survey records document the outlines of the pillars and the width of the extracted voids surrounding each pillar, which has provided a basis for a preliminary geotechnical assessment of ground stability with or without the pillars in place. Based on positive preliminary assessments, Orion has commenced a detailed study to assess whether the insertion of cemented paste fill in the surrounding voids would allow for some of these remnant pillars to be extracted without negatively impacting the long term geotechnical stability.
