Ngualla Rare Earths Project, Tanzania

Ngualla Rare Earths Project in Tanzania is one of the largest Neodymium and Praseodymium (NdPr) rare earth deposits in the world.

The project is owned and operated by Mamba Minerals Corporation Limited (MML), which is 84% owned by Peak Rare Earths via 100% owned UK subsidiary Ngualla Group UK.

The remaining 16% is with the Government of Tanzania.

The deposit was discovered by Peak in August 2010. A scoping study of the project was completed in 2012, followed by a preliminary feasibility study (PFS) in March 2014.

Ngualla received the environmental certificate in March 2017.

In April 2017, a bankable feasibility study of the rare earth project was completed. It was updated in October 2022.

The Government of Tanzania granted a Special Mining Licence (SML) for Ngualla Project to MML in April 2023.

Peak aims a Final Investment Decision (FID) on Ngualla by the end of September 2023, with construction works beginning from October 2023. The commissioning will commence in April 2025.

The construction of the project is estimated to cost approximately $320m. It will have an initial life-of-mine (LOM) of 24 years, based on ore reserves.

Location, Geology and Mineralisation

The Ngualla Rare Earths Project is located near the Ngwala Village, approximately 147km from the city of Mbeya.

Specifically, the project is centred on the Ngualla Carbonatite in southern Tanzania on the edge of the East African Rift Valley.

The Ngualla carbonatite complex, a pipe-like intrusive body featuring carbonate mineral-rich and alkaline igneous rocks, includes three major carbonatite phases and three silicate-rich igneous phases.

The major carbonatite phases include calcite carbonatite, ferroan dolomite, and magnesiocarbonatite, while silicate-rich igneous phases feature ultramafic rock and two varieties of glimmerite.

Rare earths at the property were enriched in the carbonatite intrusions by igneous processes. Weathering processes and subsequent partial erosion further upgraded the mineralisation to economic levels.

The main mineralisation zones identified in the project area include Southern Rare Earth Zone (SREZ) featuring the Bastnaesite Zone (hosted in fresh and weathered carbonatite) and Monazite Zone; Southwest Alluvials (SWA) and Northern Zone (NZ).

Other commodities such as niobium, phosphate, barite, fluorite, and vermiculite were also identified at Ngualla.

Ngualla Reserves

The project is estimated to hold measured, indicated and inferred mineral resources of 214.4Mt grading 2.15% rare earth oxide (REO), containing 4,620kt of REO.

The proven and probable ore reserve estimate for Ngualla, as of October 2022, is 18.5Mt grading at 4.80% Rare Earth Oxide (REO) for 887kt REO.

Mining at Ngualla project

As mineralisation at the Ngualla deposit is close to the surface, the project will support conventional open pit mining operation with less need for blasting.

It will involve using hydraulic excavators, dump trucks and drill-and-blast, coupled to a ROM stockpile.

The ore and waste materials are planned to be excavated in 2.5m flitches following mark-out by grade control.

The ore will be transported to the ROM pad skyway or a designated low-grade stockpile.

The extracted mine waste is planned to be hauled directly from the pit to the tailings storage facility (TSF) dam wall.

The mining fleet includes 41-tonne articulated dump trucks (Caterpillar 745) loaded by a 90-tonne excavator (Caterpillar 395). Also, a 30-tonne front-end loader (Caterpillar 980M), which can load the 441-tonne dump trucks, will be used as backup for the primary loading unit.

Overall, the project will create around 600 direct and 3,000 indirect jobs during the construction phase, and around 220 direct and 1,000 indirect jobs during operations.

Ore processing

The project will feature a multi-stage processing plant at the site to produce around 28,300 tonnes per annum of rare earth concentrate grading 45% REO.

The plant will include a ROM pad to receive mine production and blend plant feed to predefined specifications; and a comminution circuit comprising primary includes crushing, milling, grinding and classification.

It will also include beneficiation of the ground feed by using reverse gangue flotation, regrinding and rare earth flotation.

Waste solids will be disposed in a segmented TSF.

Offtake Agreements

Peak signed a non-binding memorandum of understanding (MoU) with Shenghe Resources (Singapore), a wholly owned subsidiary of rare earths company Shenghe Resources Holdings, in October 2022.

As outlined in the MoU, Shenghe will purchase 75%-100% of the production from the Ngualla Project for an initial period of seven years. The term may be extended further by the mutual agreement.

Contractors Involved

SRK Consulting was contracted to prepare the mineral resource estimates and a resource model for the Ngualla deposit.

Peak contracted Align Environment and Risk Management and Paulsam Geo-engineering company to complete environmental studies and reports required for the rare earth project.

Australia-based Orelogy Consulting prepared the ore reserve estimate for Ngualla.

MDM Engineering, Knight Piésold, and Golder Associates were involved in conducting the engineering, plant design and infrastructure studies for the project.

Peak employed ANSTO Minerals, ALS Metallurgy, Nagrom, Independent Metallurgical Operations, and Janike and Johanson to complete metallurgical and pilot plant studies for the project.

In August 2021, the company announced that Amec Foster Wheeler had been engaged to lead a Bankable Feasibility Study (BFS) Update. Amec Foster Wheeler also assisted Peak in completing the original BFS in 2017.