The United Downs Deep Geothermal Power (UDDGP) project has found some of the world’s highest grades of lithium and best overall qualities from preliminary sampling in deep geothermal waters in Cornwall.
Further sampling is planned before work begins on designing and building a lithium extraction pilot plant.
The project, involving Cornish Lithium in collaboration with Geothermal Engineering Ltd (GEL), also found traces of magnesium and potential additional by-products such as boron, rubidium, caesium and potassium at the site near Redruth.
Results showed average lithium concentrations of 220 milligrams per litre (‘mg/L’) with concentrations of up to 260 mg/L, and ultra-low levels of magnesium, 5 mg/L.
Total dissolved solids concentrations of 29,000 mg/L are lower than many other geothermal waters worldwide.
Engineers will use direct lithium extraction (DLE) to extract dissolved lithium compounds from the water avoiding large evaporation ponds used in the arid regions of South America.
DLE uses ionic adsorbents and/or ion exchange membranes, with the residual water being returned to depth via a borehole.
Rob Bowell, corporate consultant with earth and water resource industries company, SRK Consulting, said: “The lithium grades reported from the deep geothermal waters at United Downs are globally significant.
“Coupled with the low salinity of the waters, they should be highly amenable to lithium extraction using cutting-edge DLE technology.”
Cornish Lithium added that the initial results indicated some of the world’s highest grades of lithium and best overall chemical qualities encountered in published records for geothermal waters anywhere in the world.
“Geothermal waters which contain lithium are very different from other occurrences of lithium in brine given that the same water can be used to generate zero-carbon electrical power and heat.
“As such these waters are rapidly becoming recognised as the ultimate ethical source of lithium.”
Next steps for UDDGP project include further sampling of the deep geothermal waters when GEL begins its next phase of test work at the site in October this year.
The UDDGP project recently received £4 million from the Government to build a pilot lithium extraction plant at the site. bityl.co/65EU
The development will include the procurement and building of the pilot plant and trial DLE technology to extract lithium from the geothermal waters which circulate naturally in the granite rock beneath Cornwall.