St George Mining Enlists Técnicas Reunidas for Brazil Rare Earths Processing

Introduction

St George Mining Limited (the company reports) has signed a memorandum of understanding (MoU) with Spanish engineering group Técnicas Reunidas to run advanced processing test work on samples from the Araxá niobium and rare earth elements (REE) deposit in Minas Gerais, Brazil. The stated objective is to evaluate processing routes—up to and including rare earth separation—that could convert Araxá mineralization into saleable rare earth products.

Because rare earth projects are often constrained more by metallurgy and separation capability than by geology alone, the MoU is best viewed as a de-risking step: generating test-work data that can inform a hydrometallurgical processing flowsheet (aqueous-chemistry-based extraction and purification), equipment selection, and preliminary cost/energy/water assumptions.

TL;DR: The MoU focuses on metallurgy and process test work—often the critical path for moving a REE deposit from resource potential toward a buildable processing plan.

Araxá deposit: geology, mineralization style, and processing implications

Araxá sits in a region known for carbonatite-associated mineral systems (carbonatite = carbonate-rich igneous complex) that can host niobium and REE mineralization. Publicly, many carbonatite/laterite REE systems are dominated by minerals such as monazite and/or bastnäsite (common REE-bearing minerals), with impurity profiles that may include phosphate, iron, barium/strontium, fluorine, and sometimes naturally occurring radioactive materials (NORM) from thorium and uranium.

From a processing standpoint, these mineralogy and impurity factors typically drive:

• Reagent consumption (especially acids/alkalis) during leach and impurity removal steps
• Solid-liquid separation challenges (fine particles, gels, silica issues depending on gangue)
• Impurity control to meet downstream specifications for mixed rare earth carbonate (MREC) or separated oxides
• Radioactive residue handling (if thorium/uranium are present above regulatory thresholds), affecting tailings design and permitting

For general background on rare earth mineral processing and separation challenges, the U.S. Geological Survey (USGS) rare earths overview is a helpful reference, and the International Energy Agency (IEA) report on critical minerals provides context on processing bottlenecks and supply-chain concentration.

TL;DR: Araxá is likely carbonatite-related; that can be favorable for grades but often brings impurity and (potential) NORM considerations that make metallurgy and residue management central to project viability.

Project scale claims and how to interpret “larger than Mountain Pass” comparisons

St George has stated (per public disclosures) that Araxá ranks among the larger hard-rock niobium/REE accumulations and has compared its scale to the Mountain Pass operation in California. To keep this comparison technically precise, “larger” can mean different metrics—resource tonnage, contained rare earth oxides (REO), grade, or a subset such as contained NdPr (neodymium-praseodymium, the key magnet rare earths).

For readers benchmarking projects, the most defensible comparisons typically cite:

• JORC / NI 43-101 resource estimate tonnage and grade
• Contained REO (tonnes of REO within measured/indicated/inferred categories)
• Basket composition (e.g., NdPr% of total REO, plus Dy/Tb contributions)

If you are evaluating relative scale against Mountain Pass specifically, use Mountain Pass public reporting and USGS references for the U.S. supply baseline (see USGS) and then align Araxá figures to the same units (e.g., contained REO at a stated cut-off grade). Without that apples-to-apples basis, “larger” should be read as a company-reported positioning statement rather than a definitive industry ranking.

TL;DR: “Larger than Mountain Pass” needs a clear metric (contained REO vs tonnage vs NdPr); treat it as company-reported unless supported by directly comparable resource data.

Strategic alliance: what the MoU practically de-risks

The company frames the MoU as a pathway to access European processing expertise. In practical project-development terms, test work and early engineering collaboration can de-risk several items that commonly delay REE projects:

• Metallurgical recovery from the specific Araxá mineral assemblage (leach kinetics, recovery variability)
• Impurity removal (Fe, P, Ca, Ba/Sr, fluoride, and potential radionuclides)
• Product definition: whether the best near-term product is MREC, mixed oxide, or fully separated oxides
• Mass balance inputs for scoping / pre-feasibility studies (reagent, water, power, residue volumes)
• Separation readiness (whether concentrate quality is suitable for downstream separation at economic cost)

The MoU itself is not a feasibility study, financing package, or construction decision. Its value is in generating data needed to move toward staged engineering—typically progressing from bench test work to pilot-scale validation before committing to detailed plant design.

TL;DR: The MoU mainly reduces metallurgy and process-design uncertainty, which is often more critical than resource size in rare earth project execution.

What distinguishes RARETECH® from conventional REE processing (technical overview)

RARETECH® is described by Técnicas Reunidas as a proprietary process technology platform for critical materials. Because detailed flowsheets are usually confidential, a neutral way to interpret “differentiation” is to compare what good modern REE processing systems try to optimize versus conventional routes.

Most commercial REE processing flowsheets include these core steps:

• Beneficiation (upgrading ore to a mineral concentrate where feasible)
• Cracking/leaching (acid bake, caustic crack, or direct leach depending on mineralogy)
• Purification (removing Fe/Al/P/Ca and other impurities via neutralization/precipitation)
• Rare earth separation to individual oxides—most commonly via solvent extraction (SX) (liquid-liquid extraction using organic extractants) and, in some applications, ion exchange (IX) (separation using resin columns)

Where a newer platform such as RARETECH® may claim advantage—subject to verification through test work—often centers on:

• Flowsheet integration: fewer recycle loops, tighter control of pH/redox, and simpler impurity bleeding strategies to stabilize operation
• Reduced energy/water intensity: e.g., lower-temperature cracking, improved solid-liquid separation, more efficient wash circuits
• Impurity/radioactivity management: engineered precipitation steps and residue conditioning to isolate thorium-bearing streams (if present), supporting compliant tailings and waste handling
• Separation strategy: SX is industry-standard at scale, but optimized stage design, scrubbing, and strip chemistry can materially affect reagent usage, organic losses, and product purity; IX can be useful for polishing or niche separations but is often harder to scale for large tonnages

Readers looking for independent background on separation complexity can reference the US DOE and national-lab ecosystem; for example, the U.S. Department of Energy (DOE) Critical Materials program summarizes why separation and refining are bottlenecks rather than mining alone.

TL;DR: Conventional REE processing relies heavily on acid/alkali cracking and solvent extraction; the meaningful differentiators are usually reagent/energy efficiency, impurity and NORM control, and how robustly the flowsheet runs at scale.

Scope of work under the MoU: concentrate to mixed products to separated oxides

Under the MoU, Técnicas Reunidas will apply RARETECH® to Araxá samples, including test work aimed at:

• Refining rare earth mineral concentrates
• Producing mixed rare earth carbonate (MREC) and/or rare earth oxides (mixed oxide intermediate)
• Separating and fractionating individual REEs (e.g., Nd, Pr, Dy, Tb)

For industrial buyers, the step-change is between selling a mixed intermediate (lower value, easier to make) versus separated oxides (higher value but requires a rare earth separation plant with extensive SX circuits). Many non-Chinese projects start with MREC/mixed oxide and only later integrate separation—unless they have access to proven separation capacity and financing.

TL;DR: The work spans the “value ladder” from mixed intermediates to separated oxides—the latter is where most cost, complexity, and strategic value sits.

Potential expansion: hydrometallurgical flowsheet development and rare earth separation plant design

If expanded, the collaboration could cover process flow diagram (PFD) and process flowsheet design, plus conceptual/basic/detailed engineering for an industrial plant. For REE projects, key engineering decisions commonly include:

• Leach route selection (acid bake vs direct leach vs alkaline cracking) driven by mineralogy and impurity deportment
• Residue strategy: thickening/filtration, neutralization, and long-term storage design, especially if NORM is present
• SX train architecture: number of stages, extractant systems, and recycle management to deliver target purities
• Utilities: water balance, effluent treatment, power demand, and reagent storage/handling

These studies also translate metallurgy into project economics (capital expenditure and operating expenditure) and can support staged development decisions (pilot plant, pre-feasibility study, then definitive feasibility study).

TL;DR: Expansion moves from “can it work?” metallurgy to “how do we build and operate it?” engineering—especially important for a solvent extraction-based separation plant.

Downstream implications: product specs, demand pull, and REE supply chain security

For downstream users (magnet makers and OEM supply chains), the most relevant outputs are consistent NdPr oxide quality and reliable volumes. While specific product specifications for Araxá are not yet established publicly, typical industrial targets for magnet-grade oxides often require high purity with tight limits on impurities that can affect alloy performance (e.g., Ca, Fe, Si, P, and other rare earth cross-contamination). Final acceptance criteria depend on the magnet alloy route and customer qualification.

From a market standpoint, NdPr is the primary value driver for permanent magnets used in electric vehicle traction motors and direct-drive wind turbines. The IEA emphasizes that processing and refining capacity is a key constraint in the clean energy minerals supply chain, which is why “REE supply chain security” strategies increasingly focus on separation and metal/alloy conversion—not only mining.

Until Araxá publishes definitive feasibility outputs, any volume claims should be treated as conceptual. However, the MoU’s inclusion of separation/fractionation test work signals an intent to evaluate pathways to fully separated oxides (rather than only mixed intermediates), which is more directly aligned with magnet supply chains.

TL;DR: The key industrial question is whether Araxá can reliably produce qualified NdPr (and potentially Dy/Tb) at required purities and volumes—separation capability is the gating factor for supply security.

Positioning Araxá relative to global REE hubs and diversification efforts

China currently dominates global rare earth separation and downstream conversion capacity, which is why projects in the Americas and Europe are often discussed in the context of diversification. The U.S. has an operating mine at Mountain Pass, but global supply resilience depends on scaling separation plants, metal-making, and magnet manufacturing capacity outside China.

Within that landscape, Araxá’s potential strategic role (based on company intent) would be as a feed source that could support diversified refining routes—either producing mixed intermediates for third-party separation or, if economics and permitting allow, progressing toward integrated separation to deliver separated oxides to customers. This is directionally consistent with policy-driven efforts such as the EU focus on critical raw materials and local value chains (see European Commission policy background at European Commission: Critical raw materials).

TL;DR: Araxá’s relevance is tied to global diversification away from China’s separation dominance; its practical impact depends on whether it can access/enable separation capacity at scale.

Environmental and ESG considerations (water, reagents, residues, and NORM)

Rare earth processing raises ESG scrutiny largely because of chemical intensity and potential radioactive residue management. Even when radioactivity is low, high reagent use and large volumes of neutralized residue can drive water treatment needs and tailings footprint.

In that context, the value of modern hydrometallurgical optimization (and what platforms like RARETECH® typically aim to improve) includes:

• Lower reagent intensity via optimized leach/neutralization and recycle control
• Closed-loop water strategies to reduce freshwater withdrawal and improve effluent compliance
• Residue conditioning (neutralization, filtration, stabilization) to support safer storage
• NORM segregation where applicable—isolating thorium-bearing fractions can simplify compliance, but it must be validated analytically and designed to local regulations

Final ESG performance will depend on site-specific baseline studies, Brazilian permitting requirements, and demonstrated residue chemistry from test work (not just conceptual flowsheets).

TL;DR: ESG outcomes in REE projects are driven by reagent/water use and residue/NORM handling—test work is essential to quantify these and design compliant tailings and effluent systems.

Key risks and challenges in bringing a large REE project to production

Even with a large resource, rare earth projects face execution risks that industry readers will recognize:

• Metallurgical risk: variable mineralogy can reduce recovery or increase reagent consumption
• Separation complexity: SX circuits are capital intensive and sensitive to impurities and operational discipline
• Permitting and ESG: tailings design, water discharge limits, and any NORM management can extend timelines
• Capital intensity (capex): integrated mining + refinery + separation often requires substantial upfront investment
• Market volatility: REE prices (especially NdPr, Dy, Tb) can be cyclical, affecting project financeability
• Qualification timelines: magnet supply chains require customer sampling, certification, and long offtake negotiations

Recognizing these constraints helps frame the MoU as one step in a longer development pathway rather than a near-term supply event.

TL;DR: The main hurdles are metallurgy, separation capex/operability, permitting/ESG (including residue), and volatile pricing—test work reduces risk but doesn’t eliminate it.

Development stage and indicative milestones to watch

St George has characterized Araxá as “advanced,” but the most precise way to track stage is by published deliverables: resource updates, scoping study / preliminary economic assessment (PEA), pre-feasibility study (PFS), and definitive feasibility study (DFS). The MoU supports the technical workstream that typically feeds these studies.

Milestones industry readers can watch for (subject to company timelines and results) include:

• Completion of bench-scale metallurgical test work and publication of recoveries and impurity deportment
• A pilot plant decision to validate continuous operation and generate customer samples
• Selection of a base-case hydrometallurgical flowsheet and separation route (SX vs hybrid SX/IX)
• Release of a PEA/PFS/DFS with capex/opex, residue design basis, and product specifications

TL;DR: Watch for metallurgical results, pilot-scale validation, and feasibility-study milestones—these determine when (and if) Araxá can translate into real supply.

Clarifying PERMANENT vs PERMANET and the role of EU programs

The article references the EU-funded “PERMANENT (PERMANET)” initiative. To avoid confusion: use the formal project name as published by the consortium in external documentation. In general terms, EU programs often target an integrated value chain from raw materials through permanent magnet manufacturing.

For readers seeking authoritative context on EU research funding and industrial scale-up, the European Commission overview of Horizon Europe explains how consortia are funded and governed. Spain’s innovation funding landscape also includes the CDTI (Centro para el Desarrollo Tecnológico y la Innovación; Center for Industrial Technological Development), described at cdti.es.

TL;DR: Use the consortium’s published naming for PERMANENT/PERMANET; EU and CDTI programs provide R&D frameworks but do not, by themselves, guarantee commercial production.

Conclusion

The MoU between St George Mining and Técnicas Reunidas is primarily a technical de-risking step focused on hydrometallurgical processing and potential rare earth separation pathways for Araxá. The collaboration may help define whether Araxá is best positioned to deliver mixed intermediates, separated oxides, or a staged approach aligned with separation capacity constraints.

For industry stakeholders, the most decision-relevant outputs will be independently interpretable test-work results (recoveries, impurity control, residue characteristics), clarity on whether “larger than” comparisons are based on contained REO metrics, and a realistic timeline from pilot work to feasibility and customer qualification.

TL;DR: The alliance matters because processing—not mining—often determines whether a REE project becomes a reliable NdPr supplier; the next proof points are metallurgical data, pilot validation, and feasibility outcomes.

FAQ

Q: What does the MoU between St George Mining and Técnicas Reunidas actually cover?

A: A memorandum of understanding (MoU) sets out a framework for cooperation. Here it covers processing test work on Araxá samples, with the stated intent to evaluate routes from concentrate to mixed rare earth products and potentially separated rare earth oxides. It is not, by itself, a construction decision or a feasibility study.

Q: What is RARETECH® and how is it different from standard rare earth processing?

A: RARETECH® is described by Técnicas Reunidas as a proprietary processing platform. Standard industrial rare earth processing typically involves cracking/leaching, purification, and separation—most often using solvent extraction (SX). Differentiation (to be verified by test work) generally comes from improved impurity control, reduced reagent/energy/water intensity, and a more robust integrated flowsheet for producing separated oxides.

Q: Why is a rare earth separation plant such a bottleneck in the REE supply chain?

A: Separation is complex and capital intensive because individual rare earth elements have very similar chemistry. Producing separated oxides at consistent purity usually requires large solvent extraction circuits with many stages, strict impurity management, and strong operational control—this is why global separation capacity is concentrated in a limited number of regions.

Q: What kind of products could Araxá theoretically supply to magnet manufacturers?

A: Depending on test work and downstream economics, products could range from mixed rare earth carbonate (MREC) or mixed oxide intermediates to fully separated oxides such as NdPr oxide, and possibly dysprosium (Dy) and terbium (Tb) products. Magnet supply chains generally prefer qualified, consistent separated oxides, but intermediates can be a practical earlier-stage product if separation capacity is contracted elsewhere.

Q: What are the main risks that could delay or derail development of the Araxá REE project?

A: Common risks include metallurgical variability, high reagent consumption, impurity and residue/NORM (naturally occurring radioactive materials) management requirements, permitting timelines, high capex for separation facilities, REE price volatility, and long customer qualification cycles for magnet-grade products.