Sea4Value will design and implement technologies for recovering minerals and metals from seawater desalination brines. The aim is to make desalination plants the third source of valuable raw materials in the European Union.
More specifically, a multimineral and modular process will be developed, which will be the first industrially viable brine mining method.
Most projects and technologies dealing with metal and mineral recovery from brines, focus on individual elements, which makes the process economically unfeasible. Sea4Value goes one step further: it draws on a combination of advanced separation technologies and seeks to design a technical and economically feasible process for multi-element recovery.
The concept of Sea4Value draws on three principles:
1- Applying a circular supply model: Seawater brines as a resource of raw materials recovery
2- Advanced concentration, crystallisation and separation technologies
3- A multi-mineral modular brine mining process
Nanofiltration membranes for monovalent and multivalent ions separation
Polyelectrolyte multilayer nanofiltration membranes, produced using layer-by-layer, have not been used in high ionic strength, due to their instability in strong salt solution. Sea4Value will overcome this by finding a sufficient cross-linking of layers.
The selective calcium precipitation process will reduce scaling problems in membrane processes and avoid interferences in the developed technologies. One of the main innovations and benefits of removing calcium is to minimize the magnesium removal in the successive steps of the process.
Advanced multi-effect distillation
Even if this is the third desalination technology worldwide, there is a room for improvement. In the Sea4Value project new thermally conductive polymer composite tubes will be developed for the specific process conditions, leading to the enhancement of thermal conductivity in radial tube direction.
Advanced membrane crystallisation
When using brines, impurities resulting from precipitation of gypsum and calcium carbonate affect the product purity. Sea4Value aims to improve the purity of magnesium hydroxide by using cation exchange membranes.
Ion-selective polymer inclusion membranes (PIM)
Polymer inclusion membranes are selective dense membranes for the transport of organic molecules, cations or anions, depending on the nature of the carrier. For the selective recovery of gallium and rubidium, Sea4Value aims to develop membranes which has not been studied before. For this, membranes including ionophores selective will be produced.
Electrodialysis with bipolar membranes (EDBP)
It was demonstrated that electrodialysis concentrates sodium chloride from seawater desalination plants brines with competitive electrical consumptions. For the selective recovery of boron, Sea4Value will evaluate the application of this technology. Monovalent anion-exchange membranes to enhance the concentration factors will be used.
3D-printed adsorption modules
The use of adsorption technology in low concentration metals recovery from seawater brines is hindered due to the presence of much higher concentrations of other minerals. For the selective recovery of boron, indium, vanadium, molybdenum and scandium, Sea4Value will use 3D printing to develop new adsorbents with improved performance in terms of the concentration factors.
Ionic liquid solvent extraction
Ionic liquids are one of the major trends in this green revolution, due to its very low volatility and flammability, high thermal stability and hydrophobicity. In Sea4Value commercial ionic liquid will be used -for the first time- to selectively recover indium from brines.
Binary extractant solvent extraction
A proof-of-concept has been provided with batch lab-scale experimentation on synthetic brines. Sea4Value will apply this concept to real seawater desalination plants streams for the selective recovery of magnesium.
Synergic solvent extraction combined with Solvometallurgy
Concentrated seawater desalination plants brine contains lithium in the range of 5-7 ppm. Up until now, no commercial process is available for production of lithium from seawater resources. The Sea4Value project will optimized extractants and solvents and develop a solvometallurgical process for the selective recovery of battery-grade lithium carbonate.
Non-Dispersive solvent extraction (NDSX)
Studies have demonstrated that supported liquid membranes, which are a combination of polymeric membranes and extractants, are very effective in removing and recovering metals from liquid effluents at low concentration. Sea4Value will evaluate the use of non-dispersive solvent extraction for the selective recovery of trace metals such as indium, vanadium and molybdenum in highly saline media.
In order to design methodologies for set-up and integration of these technologies, mathematical models will be developed to create a process simulation tool. This tool will set the basis creating a modular mineral and metals production processes for the different brine compositions specific.
Separating, concentrating and crystallising technologies for ten metals and minerals will be validated within the first 30 months of the project in laboratories. Afterward, during the last 18 months of the project’s lifetime, a moving lab will be designed and installed at 2 operating plants to validate the technical feasibility in 2 different oceanic settings: Mediterranean (Denia, Spain) and Atlantic (Fonsalia, Canary Islands, Spain).