From brine chemistry to flowsheet: a screening framework for direct lithium extraction in geothermal and oilfield co-production settings

Direct lithium extraction (DLE) from geothermal and oilfield brines is supported by many technology reviews, yet an operator holding a brine analysis still lacks a structured route to a defensible choice of technology. The review organizes published evidence into a decision-directional screening framework mapping a co-produced brine’s chemistry, flow rate, reinjection specification and thermal integration limits onto the DLE families that remain feasible, those excluded, and the pre-treatment train implied. Chemistry windows are compiled for sorbents, ion sieves, membranes, electrochemical routes, capacitive deionization and solvent extraction, with thresholds traced to their sources and disagreements reported as ranges rather than resolved silently. Interactions that single-parameter screening misses, including silica scaling against sorbent temperature windows, naturally occurring radioactive material (NORM) accumulation on beds, and reinjection limits, are treated explicitly. Four pilot settings, the Salton Sea, the Upper Rhine Graben, Cornwall and the Smackover Formation, are reread through the framework, yielding its central pattern: every co-production project that has advanced to hardware has selected a sorption route, in three of the four an aluminium-based or proprietary sorbent operated warm to hot. A stepwise screening procedure is proposed and is then run forward, from public data only, on a project that did not shape it, E3 Lithium’s Leduc brine in Alberta; the forward reading is concordant with the route selected there and shows the grade gate to be a boundary of demonstrated practice rather than of feasibility. The procedure remains an unvalidated synthesis, and the research needed to validate it is set out.