ASX-listed development company Peak Resources expects the bankable feasibility study (BFS) for its Ngualla rare earths project, in Tanzania, to be completed in the first quarter of 2017, advancing the project closer to production.

Peak MD Darren Townsend says the slight delay in the start of the Ngualla pilot leach plant and the Christmas/New Year holiday period have delayed the project’s BFS completion date from late 2016 to early 2017.

Having established a pilot plant for its beneficiation process in November, Peak focused on the construction of a pilot leach plant in the first quarter of 2016. Townsend says the pilot plant is meant to demonstrate the leach process and provide detailed engineering data for the BFS.

The plant, commissioned in the second quarter of 2016, is located at a pilot facility in the minerals division of Australian research institution Australian Nuclear Science and Technology Organisation, in eastern Australia.

Townsend explains that 2 t of concentrate – generated by the beneficiation pilot plant in December – with a rare-earth oxide grading of 40%, will be treated by the pilot leach operation. He adds that the leach process comprises four main stages – an alkali roast, a water wash, the selective leach and purification.

The first stage comprises a dry roast with a common alkali, followed by a simple water wash to remove the fluorine (as it would be problematic downstream), and a selective leaching process using a low strength (less than 1%) hydrochloric acid to selectively target the high-value rare earths, while rejecting the rare-earth metal cerium and impurities. The leach process is completed when the remaining impurities are removed through precipitation using a lime slurry and filtration.

Townsend notes that the alkali leach flowsheet was selected because it can reject the majority of impurities and the loss-making cerium.

Low-Cost Operation
An update on Ngualla released in March reported a 10% reduction in capital costs and an 18% reduction in operating costs.

The update refuted the 2014 prefeasibility study, which estimated that the project would require a capital investment of $367-million to produce 10 000 t/y of rare earths over a mine life of about 50 years.

Peak reported that the expected capital costs for the Ngualla project had been reduced to $330-million, while operating costs declined to $97-million a year over a mine life of 31 years.

Townsend says the significant cost reduction is the result of a higher-grade mineral resource and enhanced flowsheet efficiency. This enhancement specifically pertains to Peak’s ability to produce a much higher-grade mineral concentrate through the beneficiation and the selective leach processes, which reduce downstream reagent use and the plant’s size.

“The lower costs are enabled by the combination of unique fundamentals that include the high-grade, thick blanket of largely free-dig mineralisation at surface, comprising consistent and favourable mineralogy for processing. An additional key factor is Peak’s extractive process that is focused on the production of high-value, high-demand magnet metal rare-earth neodymium and praseodymium, rather than large amounts of loss-making cerium that current operations must produce.”

He adds that current rare earths operations produce cerium because the cerium price was initially very favourable, but, by the time the price plummeted, the mines had already been operational using processing plants specifically designed to extract cerium. Additionally, some ores cannot be treated with Ngualla’s planned beneficiation and leach processes because of their composition.

Capital costs for the project include generator sets, an accommodation camp and a mining fleet. Townsend says Peak is focused on keeping operating costs low and competitive. Therefore, any potential cost reductions will not be at the expense of operating costs.

Capital costs also include a base case for a European Union- (EU-) based refinery to produce high-purity separated products. Townsend notes that an EU location for the refinery is preferred, owing to several operational, cost and end-market reasons. “A local source of cost-effective bulk reagents required for the refinery is essential to reduce costs and simplify transportation logistics to enable Peak to be competitive among existing producers. The availability of low-cost power and specialist support services and infrastructure, together with a location close to some consumers, are also advantageous.”

Other Attributes
Peak appointed Tanzanian ambassador Paul Rupia as a special adviser to its board last month. Townsend points out that Rupia has extensive knowledge and experience of Tanzanian regulatory systems and will offer the company valuable advice as it moves through the permitting processes for Ngualla.

His experience and input into all areas of operation in Tanzania, including community relations, will also be valuable to Peak in future, Townsend adds.

He notes that, from a technical standpoint, Ngualla has always performed well, owing to its fundamental advantages and its processing focus, the latter of which is aligned to the realities of the new rare earths market.

He points out that, as a result of the project’s technical advantage, Peak has spent “a fraction” of what other developers have spent on developing their projects.

“Rare earths production is complex, so there is still work to be completed in . . . engineering, project permitting and the offtake agreements needed to enable the company and its strategic partners to raise enough capital to get Ngualla to production.”

Townsend concludes that Ngualla differs from the majority of current rare earths projects because of its ethically sustainable development model and long-term production profile aligned to the magnet metal market.