OZ Minerals has updated its notable expansion study saying that installing a vertical boom to replace a haul truck is technically and economically viable. Study update is based on a conservative interim case containing only one-third of the total resources inferred from Prominent Hill of 59 million tons outside the current life span of the mining plan. Prominent Hill is a major copper / gold / silver mine in South Australia.
OZ Minerals will now invest A $ 47 million to advance the study. The bulk of the investment will be directed towards further backfilling to convert the excavated resources into reserves to inform the final investment decision expected in mid-2021.. Over the past decade, Prominent Hill has witnessed positive conversion of inferred mineral resources into specific mineral resources (or better) at a conversion rate greater than 1: 1 on a confined mineral basis..
The study update confirms the installation of an aircraft with a length of 1360 m, 7. Column 5m Diameter Column on Promenade Hill is technically and economically viable with consistent capital investment across temporary and augmentative states. The durability of the investment in the shaft has been tested by studying the feasibility of mining existing ore reserves with a goal of a production based on approximately 6 million tons per year from 2025 which comprises less than 30% of the mineral resources developed. The main components are as follows:
The interim case demonstrates that converting to a vertical column would reduce operational risks of mining in depth and be NPV and positive cash flow on the current mining operation of haulage trucks. The economies have so far supported continuous investment in studying expansion to conduct more drilling operations to increase the life of the mine and inform the final investment decision.
The study update clarifies that expanding the column relocation will require a capital cost of around A $ 450 million (which is not expected to increase materially if there is a transfer of resources devised to reserves to expand the study scope) to be spent over four years from 2021 and potential:
Given the proposed move to an electrified shaft as the primary method for vertical transportation to replace diesel-powered trucks, it has been shown that the emission intensity per ton of treated material will likely decrease. Battery-powered underground mining fleet and low-energy processing technologies are also being investigated as part of the study, along with renewable energy alternatives to auxiliary infrastructure..
OZ Minerals Managing Director and CEO Andrew Cole said: “The positive results of the Prominent Hill expansion study in a relatively small case increases our confidence in Prominent Hill’s continued performance.. While examining only a portion of the mineral resource, the study showed a significant increase in cash flow, improved safety, and reduced mining costs and emissions intensity. . It provides a solid foundation on which to consider the potential of the remaining two-thirds of the resource inferred as the study progresses and drill the pits to inform the investment decision in mid-2021. We understand the silver object and the mining methods used. We have consistent historical resources to maintain conversion rates. Underground mining rates now average around 4 million tons per year and we expect to achieve rates between 4-5 million tons per year as of 2022 when we will be able to mine simultaneously from the bottom of the mine plan and from current mining levels.. The mine has consistently operated in the lower quadrant of the cost curve for many years. We look forward to the results of the study and further excavation work in mid-2021.
The column design concept consisted of a concrete-lined column 1360 m deep with a nominal diameter of 7. 5 m. Column construction at this stage is assumed to be a conventional blind basin. The sinking rate of this type of method is about 2 meters per day which indicates a sinking period of about two years. The shaft collar location is finalized as a compromise between the distance from the underground mine work in depth and the open hole mined to ensure the long-term stability of the column. A geotechnical hole is being drilled for pole up to 1500 m to confirm the suitability of the preferred shaft location.
Geotechnical drilling, rock strength measurements and stress and numerical modeling were performed to support risk management of the transition to mining at greater depths, while maintaining the current primary and secondary mining sequence approach. The ostrich is designed to feed the trucking horizon, as materials are trucked from the base of the ore lanes to the fracturing infrastructure and the shaft underground..
This design allows for more efficient mining activities, allowing for increased downtime turnover to support the rate of mining over the current mining plan. The installation of these dedicated facilities will allow metallic materials currently being trucked to the surface to be directed towards the shaft to improve efficiency and cost profile, enabling a reduced cost base for the process.
Infrastructure such as reduced main access and additional ventilation are common in both trucking and shaft expansion. The early advance of these common elements presents an opportunity to further remove bottlenecks to the existing process and accelerate potential column expansion. These activities started during 2020 as the current decline in the mining sector accelerates.
Prominent Hill, Oz Minerals, Andrew Cole, Gold, Copper
World News – AU – OZ Minerals plans vertical lift of &’s underground electric fleet to expand Proment Hill – International Mining