Name of the Project
Ngualla rare earths project.

Location
Tanzania.

Project Owner/s
Peak Resources.

Project Description
The Ngualla project has been confirmed as having the potential to become one of the lowest-cost and highest-quality rare earths projects worldwide. The project has a mineral ore reserve of 18.5-million tonnes grading 4.8% rare-earth oxide (REO).

An optimisation study completed on the project in August envisages a mine life of 26 years, compared with 31 years in the bankable feasibility study (BFS) completed in April. This is based on the weathered Bastnaesite zone mineralisation, which comprises only 22% of the total Ngualla mineral resource estimate at a 1% REO lower-grade cutoff.

Ore mill feed has increased from 624 000 t/y in the BFS to 711 000 t/y in the optimisation study, while processed mineral concentrate has been estimated at 32 700 t/y, compared with 28 300 t/y in the BFS.

Planned final products from the project are: 
• 2 810 t/y of neodymium and praseodymium rare-earth oxide (2N min 75% neodymium oxide), 
• 625 t/y of mixed samarium/europium gadolinium and mixed heavy rare-earth carbonate, and
• 3 475 t/y of cerium carbonate and 7 995 t/y of lanthanum carbonate. 

A capacity analysis of the multistage processing facility at Ngualla in the optimisation study has identified the rare earths flotation stage as the primary bottleneck in the circuit as designed for the BFS. The capacity of this stage of the circuit is a function of the size and number of the flotation cells and the residence time that the ore must stay in each cell to achieve the desired recovery.

A reduced residence time thus means the amount of ore passing through the circuit can be increased without changing the size or number of cells. 

Removing the process bottleneck from the rare earths flotation cells shifts the capacity constraint to the ball mill. By maximising the throughput of the existing ball mill at an additional capital cost of $4-million and a slightly accelerated BFS mining schedule, the average mill feed and corresponding concentrate production can be increased by an estimated 16% a year. 

Analysis of the proposed refinery expansion in Tees Valley, in the UK, has identified that the capacity constraints of increasing the throughput to take the additional processed product from Ngualla are the three solid liquid separation processes. 

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project’s post-tax and royalties net present value, at an 8% discount rate, has decreased from $633-million in the BFS to $612-million in the process optimisation study. The internal rate of return has increased from 21% to 22%.

Payback has been estimated at five years.

Capital Expenditure
The capital cost of the project has increased from $356-million in the BFS to $365-million in the optimisation study for Ngualla and the Tees Valley refinery.

Planned Start/End Date
Construction on the site is expected to start by the end of September 2022 with production targeted to start in September 2024.

Latest Developments
Peak Resources has announced that its recently appointed technical team has been successfully integrated into the BFS update process; and the identification of an opportunity to further optimise the value of its integrated Ngualla-Teesside project by pursuing an increase in concentrator capacity.

The scope of the BFS update has been amended to allow for an increase in the Ngualla flotation plant average life-of-mine (LoM) capacity to 800 000 t/y. This reflects an estimated 28% increase in capacity over the average LoM capacity of 624 000 t/y in the BFS published in April 2017 and an estimated 13% increase in the average LoM capacity of 711 000 t/y that was reflected in an internal optimisation study completed in August 2017.

This higher mine-concentrator throughput would increase the average LoM neodymium and praseodymium rare-earth oxide production to between 3 000 t/y to 3 500 t/y, compared with the 2 420 t/y reflected in the April 2017 BFS and the 2 810 t/y reflected in the August 2017 optimisation.

As part of the BFS update, testwork will be undertaken before the final investment decision to support detailed design. The programme of work will be focused on optimising neodymium and praseodymium rare-earth oxide operating costs in the mining and the two processing plants, as well as further decreasing the startup risks.

An expansion in capacity is expected to support a material increase in the value of the integrated Ngualla-Teesside project particularly given the strong appreciation in neodymium and praseodymium rare-earth oxide prices since the April 2017 BFS and August 2017 optimisation were completed.

Key Contracts, Suppliers and Consultants
None stated.

Contact Details for Project Information
Peak Resources, tel +61 8 9200 5360, fax +61 8 9226 383 or email info@peakresources.com.au.