The Technology
How we extract critical raw materials
from geothermal brines
How we extract critical raw materials
from geothermal brines
Introduction
The Cesano geothermal brines are a complex mixture of dissolved salts, minerals and heat. Unlocking their full value requires a carefully sequenced, integrated process — one that separates each target material at the right stage, in the right form, without wasting energy or generating liquid waste. This is exactly what BRAIN has been designed to do.
The resource
The starting point is the geothermal brine itself, pumped from deep wells at the Cesano site. This hot, mineral-rich fluid contains three raw materials simultaneously: potassium at concentrations up to 69,700 mg/L, boron up to 10,500 mg/L, and lithium up to 180 mg/L - alongside sodium chloride and other dissolved salts. The heat carried by the brine is not wasted: it powers the extraction process itself, making the entire operation renewable-energy driven.
How we extract critical raw materials
from geothermal brine
Our Process
01
Evaporation & SOP crystallisation
The hot brine is evaporated under controlled conditions, causing potassium and sulphate to crystallise as high-purity SOP — a commercial-grade fertiliser. Lithium and boron remain concentrated in solution for the next stages.
02
Boron separation
The SOP-depleted brine undergoes selective boron extraction using innovative ionic liquid-based solvents. These green, regenerable reagents achieve high recovery rates, producing boron in a form ready for industrial use.
03
Lithium purification and battery-grade production
The lithium-enriched solution is further refined through ion exchange and crystallisation to remove residual impurities. The result is battery-grade lithium carbonate (≥99.5% Li₂CO₃) meeting the standards required by battery manufacturers.
04
Zero liquid discharge and brine reinjection
The process runs as a closed loop. Liquors are recycled internally to minimise waste, and at least 70% of the treated brine is reinjected into the geothermal reservoir — ensuring long-term sustainability.
The pilot plant
To validate this process under real operating conditions, BRAIN will design, build and operate a modular pilot plant capable of processing 400 kg of brine per day. The plant will be located at an authorised industrial site near L’Aquila, operated by the University of L’Aquila’s RIF-IND research group, which already runs a mobile pilot facility (FENIX) used in previous European projects.
The pilot plant will be tested in three experimental cycles: first with synthetic brines replicating Cesano’s composition, then with progressively more complex mixtures, and finally with real geothermal brine extracted directly from the Cesano wells. This step-by-step approach reduces technical risk and ensures that every element of the process is validated before scale-up.
Digital process models (built using ASPEN Plus® and COMSOL®) will run in parallel, allowing the team to simulate and optimise the full system and provide the technical backbone for the Feasibility Study.
Our Process
01
Evaporation & SOP crystallisation
The hot brine is evaporated under controlled temperature and pH conditions. As the solution concentrates, potassium and sulphate ions combine to form Glaserite, an intermediate salt that is then converted into high-purity potassium sulphate (SOP). This two-stage crystallisation process, already validated at laboratory scale, produces SOP meeting commercial fertiliser-grade specifications (>50% K₂O equivalent) while concentrating lithium and boron in the remaining solution for the next stages.
02
Boron separation
The SOP-depleted brine is treated to selectively extract boron. BRAIN is developing and testing multiple complementary approaches, including selective precipitation and innovative ionic liquid-based extraction — a green solvent technology that offers high selectivity and can be regenerated and reused. The target is to recover over 70–85% of the boron present, producing it in a chemical form suitable for industrial applications.
03
Lithium purification and battery-grade production
With potassium and boron removed, the remaining solution is enriched in lithium. Advanced purification steps — including ion exchange resins and fractional crystallisation — selectively remove residual impurities such as sodium, calcium and magnesium. The final product is lithium carbonate at battery-grade purity (≥99.5% Li₂CO₃), meeting the strict quality standards required by battery manufacturers.
04
Zero liquid discharge
and brine reinjection
The process is designed as a closed loop. Mother liquors from the crystallisation stages are recycled back into the process, minimising reagent consumption and waste generation. At least 70% of the treated brine is reinjected into the geothermal reservoir, ensuring the long-term sustainability of the resource.
Why this approach is different
Conventional lithium extraction relies either on hard rock mining — energy-intensive and environmentally disruptive — or on solar evaporation ponds in South America, which require vast land areas and months of processing time. BRAIN offers a fundamentally different model: a compact, closed-loop, geothermally powered process that co-produces three valuable materials from a single fluid stream, with a carbon footprint targeted at below 2.6 kg CO₂ per kg of lithium carbonate produced.
The modular design also means the process is not tied to Cesano alone. It is conceived to be replicable at other geothermal sites across Italy — including Larderello and the Campi Flegrei area — and potentially across Europe, wherever mineral-rich geothermal fluids are found.
Step 1
Evaporation
& SOP crystallisation
The hot brine is evaporated under controlled temperature and pH conditions. As the solution concentrates, potassium and sulphate ions combine to form Glaserite, an intermediate salt that is then converted into high-purity potassium sulphate (SOP). This two-stage crystallisation process, already validated at laboratory scale, produces SOP meeting commercial fertiliser-grade specifications (>50% K₂O equivalent) while concentrating lithium and boron in the remaining solution for the next stages.
Step 2
Boron separation
The SOP-depleted brine is treated to selectively extract boron. BRAIN is developing and testing multiple complementary approaches, including selective precipitation and innovative ionic liquid-based extraction — a green solvent technology that offers high selectivity and can be regenerated and reused. The target is to recover over 70–85% of the boron present, producing it in a chemical form suitable for industrial applications.
Step 3
Lithium purification and battery-grade production
With potassium and boron removed, the remaining solution is enriched in lithium. Advanced purification steps — including ion exchange resins and fractional crystallisation — selectively remove residual impurities such as sodium, calcium and magnesium. The final product is lithium carbonate at battery-grade purity (≥99.5% Li₂CO₃), meeting the strict quality standards required by battery manufacturers.
Step 3
Lithium purification and battery-grade production
With potassium and boron removed, the remaining solution is enriched in lithium. Advanced purification steps — including ion exchange resins and fractional crystallisation — selectively remove residual impurities such as sodium, calcium and magnesium. The final product is lithium carbonate at battery-grade purity (≥99.5% Li₂CO₃), meeting the strict quality standards required by battery manufacturers.
How we work:
Comprehensive study of the Cesano geothermal resource: preparation and validation of synthetic brines replicating real brine composition; geochemical and geothermal characterisation of the reservoir; laboratory-scale extraction tests for lithium, SOP and boron; development and testing of ionic liquids for selective boron separation.
Digital process simulation; risk analysis; detailed engineering and construction of the pilot plant; experimental campaigns with synthetic and real brines; process optimisation.
Life Cycle Assessment (LCA) in accordance with ISO 14040/44 standards; benchmarking against existing technologies; Environmental Impact Assessment (EIA) to support future permitting.
CAPEX/OPEX estimation; market analysis and business modelling; regulatory compliance assessment; roadmap to full industrial scale.
