Reporting on its Platreef project near Mokopane in its recent second quarter results (to 30 June 2019), Ivanhoe Mines says it is investigating an alternative production plan, targeting significantly lower initial capital, to accelerate first production by using Shaft 1 as the mine’s initial production shaft.
This plan will focus on initially targeting the development of mining zones accessible from Shaft 1 and maximising the hoisting capacity of this shaft, followed by expansions to the production rate as outlined in the DFS.
Testing the ventilation at Shaft 1’s 750-metre-level station (photo: Ivanhoe).
Shaft 1 reached the top of the high-grade Flatreef deposit (T1 mineralised zone) at a depth of 780,2 m below surface in Q3-2018 and has since been extended to a depth of more than 900 m below surface. The thickness of the mineralised reef (T1 and T2 mineralised zones) at Shaft 1 is 29 m, with grades of platinum group metals ranging up to 11 g/t 3PE (platinum, palladium and rhodium) plus gold, as well as significant quantities of nickel and copper. The 29‑m intersection yielded approximately 3 000 tonnes of ore, estimated to contain more than 400 ounces of platinum group metals. The ore is stockpiled on surface for further metallurgical sampling.
The 750-metre-level and 850-metre-level stations have both been completed and will provide initial, underground access to the high-grade orebody, enabling mine development to proceed during the construction of Shaft 2. As sinking of Shaft 1 advances, one more station will be developed at a mine-working depth of 950 m. Shaft 1 is expected to reach its projected, final depth of 982 m below surface in early 2020.
The DFS planned for Shaft 1 to ultimately become the primary ventilation shaft during the project’s 4 Mt/a production case.
Shaft 2, to be located approximately 100 m north-east of Shaft 1, will have an internal diameter of 10 m. It will be lined with concrete and sunk to a planned, final depth of more than 1 104 m below surface. It will be equipped with two 40-tonne, rock-hoisting skips capable of hoisting a total of 6 Mt/a of ore – the single largest hoisting capacity at any mine in Africa.
The headgear for the permanent hoisting facility was designed by Murray & Roberts Cementation. The boxcut excavation to a depth of approximately 29 m below surface, including the concrete foundation (hitch), has been successfully completed. It will form the foundation of the 103-m-tall concrete headgear that will house the shaft’s permanent hoisting facilities and support the shaft collar.
The mining zones in the current Platreef mine plan occur at depths ranging from approximately 700 m to 1 200 m below surface.
Mining of the Platreef will be highly mechanised and mining methods to be employed will include long-hole stoping and drift-and-fill mining. Each method will utilise cemented backfill for maximum ore extraction. As per the DFS, the ore will be hauled from the stopes to a series of internal ore passes and fed to the bottom of Shaft 2, where it will be crushed and hoisted to surface.
In respect of the water supply for the project, Ivanhoe says that in May last year it signed a new agreement to receive local, treated water to supply most of the bulk water needed for the first phase of production at Platreef. The Mogalakwena Local Municipality has agreed to supply a minimum of 5 million litres of treated water a day for 32 years, beginning in 2022, from the town of Mokopane’s new Masodi Treatment Works. Initial supply will be used in Platreef’s ongoing underground mine development and surface infrastructure construction.
Under the terms of the agreement, which is subject to certain suspensive conditions, Ivanplats will provide financial assistance to the municipality for certified costs of up to a maximum of R248 million to complete the Masodi plant. Ivanplats will purchase the treated wastewater at a reduced rate of R5 per thousand litres for the first 10 million litres per day to offset a portion of the initial capital contributed.
Ivanplats received its Integrated Water Use Licence in January 2019, which is valid for 30 years and enables the project to make use of water as planned in the 2017 DFS.
The Platreef project is owned by Ivanplats, which is 64 %-owned by Ivanhoe. A 26 % interest is held by Ivanplats’ historically-disadvantaged, broad-based, black economic empowerment (B-BBEE) partners, while a Japanese consortium of ITOCHU Corporation, Japan Oil, Gas and Metals National Corporation and Japan Gas Corporation
owns a 10 % interest.
