Optimal testwork jags world-best rare earths recovery for Viridis

Viridis Mining & Minerals has delivered outstanding magnet rare earth results from its metallurgical testwork conducted on a bulk mixed sample sourced from the company’s Southern Complex deposits at its Colossus project in the renowned Minas Gerais mining region in Brazil.

The company believes the results will position the potentially massive play as the global leader among ionic adsorption clay (IAC) projects.

Management says the testwork, completed by the Australian Nuclear Science and Technology Organisation (ANSTO), produced the highest known recoveries and the lowest impurity levels for magnet rare earths for a publicly listed IAC project.

A mixed rare earth carbonate (MREC) was produced from a 41kg bulk sample and returned what the company says are world-beating overall magnetic rare earths oxide recoveries of 78 per cent from its Southern Complex, which comprises the Cupim South and Centro Sul deposits.

In comparison, its Northern Concessions area returned 76 per cent recoveries.

The impurity levels from the tested material showed low levels of radionuclides and gangue elements, helping to form a superior concentrate.

The company says the MREC product’s ratio of high magnetic rare earths to total rare earth oxides (TREO) of 38 per cent and low impurity levels will help facilitate offtake discussions.

The impurity levels were a stunningly low 0.7 per cent, bettering the Northern Concessions already-impressive 1 per cent total.

A high percentage of the valuable four magnetic rare earths were recovered from ANSTO’s testing, with the more valuable dysprosium (65 per cent) and terbium (69 per cent) returning a combined 66 per cent overall. This compares to a 68 per cent recovery rate at the Northern Concessions.

The magnetic rare earths praseodymium (77 per cent) and neodymium (79 per cent) contributed to the overall 78 per cent recovery level for the four magnetic rare earths oxides.

Viridis says it will deliver a high-quality rare earths basket from ore sourced from various deposits across the Colossus project, with the Northern Concessions previously returning 39 per cent magnetic rare earths to TREO, in addition to the Southern Complex’s 38 per cent.

This should provide quality ore feed to support a long-life mining operation, the company says.

The extensive testing was completed to ensure we had all the appropriate data to build a robust flowsheet design, but coming out the other side with these industry-leading results has put Colossus firmly at the top of rare earths projects globally with a long-life, high-grade mine plan and exceptional recoveries.

Moreno said the company’s focus has always been to build a resource base with a high concentration of magnet rare earth oxides in the ore, due to the economics of the project being linked to the MREO to TREO ratio.

ANSTO designed a practical flowsheet to produce the MREC from Viridis’ bulk clay material using a low-cost ammonia sulphate, leaching at a pH of 4.5 at room temperature with a 30-minute residence time.

The 41kg bulk sample consisted of 35 smaller samples sourced from 26 drill holes.

The bulk material was separated into three sub-samples and tested for head assay data, returning an average grade of 4561parts per million (ppm) TREO and 1506ppm magnet rare earths oxides.

A stellar grade of 58 per cent magnet rare earths to TREO (the balance being carbonate) from the company’s southern ground adds to the impressive 78 per cent recoveries of the valuable magnetic metals.

The results are a vital input into the upcoming scoping study expected to be issued before the end of March, in addition to the pending mineral resource upgrade.

The company also plans to lodge three environmental permits shortly as part of finalising its environmental impact assessment for a preliminary environmental licence application.

Notably, based on the recovery levels from ANSTO’s testing and flowsheet design, the Southern Complex could potentially recover a net 1147 tonnes of valuable magnetic rare earths for each 1 million tonnes of ore that is processed.

Based on the expected size of the total Colossus resource, the project has the potential to churn out a lot of mixed rare earths carbonate in the coming years.

Is your ASX-listed company doing something interesting? Contact: matt.birney@wanews.com.au