This technical report describes the processing facilities at the Oyu Tolgoi copper-gold mine in Mongolia, covering the commissioned Phase 1 concentrator and the proposed Phase 2 expansion to treat underground ore.
Report context
This NI 43-101 technical report for the Oyu Tolgoi Joint Venture in Mongolia is dated July 2021 (Project Number: 247026). The report addresses the Phase 1 concentrator, commissioned in early 2013, and the proposed Phase 2 concentrator development program for treating ore from the Hugo North/Hugo North Extension underground deposit via Lift 1 in conjunction with ongoing open pit mining.
Processing route
Phase 1 concentrator (commissioned and operating)
The Phase 1 concentrator was commissioned in early 2013. The nameplate processing capacity of 96 kt/d was achieved in August 2013. The process plant employs a conventional semi-autogenous grind (SAG) mill/ball mill/grinding circuit (SABC) followed by flotation.
Phase 1 uses two grinding lines (Lines 1 and 2), each consisting of a SAG mill, two parallel ball mills, and associated downstream equipment to treat up to 100 kt/d of ore from the Oyut open pit. Operating data from Phase 1 have been used in Phase 2 design.
Phase 2 concentrator (proposed design)
The intent of Phase 2 is to treat all of the high-value Hugo North/Hugo North Extension Lift 1 ore able to be delivered by the mine, with any additional throughput capacity being satisfied by OTLLC's open pit ore. The Phase 2 concentrator development program will optimize the concentrator circuit to enable it to maximise recovery from the higher-grade Hugo North/Hugo North Extension Lift 1 ore and to allow it to handle higher tonnage throughput.
Components that require upgrading to accommodate the gradual introduction of ore from underground include: ball milling; rougher flotation; cleaner columns; concentrate filtration, thickening, and bagging areas; and bagged concentrate storage facilities.
Processing arrangements for Entrée
Entrée's share of products will, unless Entrée otherwise agrees, be processed at the OTLLC facilities by paying milling and smelting charges. The OTLLC facilities are not intended to be profit centres and therefore minerals from the Entrée/Oyu Tolgoi JV property will be processed at cost. OTLLC will also make the OTLLC facilities available to Entrée at the same terms if spare processing capacity exists to process other suitable mill feed.
Reagents, power, and water
Reagents and media required will include lime, primary collector, secondary collector, frother, tailings flocculant, water treatment chemicals, and grinding media.
With the addition of the concentrator conversion loads, the peak operating load demand from the existing 220 kV concentrator substation will increase by an estimated 20 MW (from 116–136 MW), and the nominal operating (diversified) load will increase by an estimated 19 MW (from 106–125 MW). The concentrator raw water demand varies seasonally. Annual average raw water demand is projected to be 0.45 m³/t ore processed.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Phase 1 nameplate processing capacity | 96 kt/d | Design (achieved August 2013) |
| Phase 1 throughput capacity | up to 100 kt/d | Operating data |
| Phase 1 grinding lines | 2 lines (each: 1 SAG mill, 2 parallel ball mills) | Design |
| Phase 1 concentrator commissioning | Early 2013 | Actual |
| Phase 1 circuit type | SABC (SAG mill/ball mill/grinding circuit) followed by flotation | Design |
| Phase 1 ore source | Oyut open pit | Operating data |
| Phase 2 ore source | Hugo North/Hugo North Extension Lift 1 (underground) plus open pit ore | Proposed design |
| Phase 2 concentrator conversion – peak load increase | +20 MW (from 116–136 MW) | Estimated |
| Phase 2 concentrator conversion – nominal load increase | +19 MW (from 106–125 MW) | Estimated |
| Concentrator annual average raw water demand | 0.45 m³/t ore processed | Projected |
| Reagents and media | Lime, primary collector, secondary collector, frother, tailings flocculant, water treatment chemicals, grinding media | Proposed design |
Project website: https://www.entreeresourcesltd.com/projects/entree-oyu-tolgoi-joint-venture/
Project website: https://turquoisehill2021ir.q4web.com/turquoise-hill/oyu-tolgoi/
Project website: https://turquoisehill2021ir.q4web.com/home/default.aspx
Project website: https://www.ot.mn/en
Technical qualifications
The Phase 2 concentrator development program is described as proposed design and optimization, with operating data from Phase 1 having been used in Phase 2 design. The concentrator raw water demand is projected, and the power load increases for the concentrator conversion are estimated. The report does not provide final flowsheet details, performance guarantees, or economic outcomes for Phase 2.
Source: Oyu Tolgoi Joint Venture, Mongolia, NI 43-101 Technical Report, July 2021, Sections 1.15 and 1.16.
