Response to Concept 5, One of Many Possible Responses

The first parameter to measure might be the mass of recoverable lithium in the deposit using measurements of the concentration of lithium in the brine and accounting for variable specific yield. The second might be to analyze for secondary ions such as bromide, magnesium, or actinide and lanthanide elements that might be valuable if extracted along with the lithium. One might also evaluate whether it is feasible to use an evaporation pond to further concentrate the brine before processing. That is, to determine the thermodynamic activity of the brine relative to local relative humidity and also evaluate whether the pond would present a hazard to migrating waterfowl. One then might ask how difficult it would be to extract the brine, that is, what is the hydraulic conductivity and specific yield of the aquifer and how many wells would be needed for the optimum rate of withdrawal. The optimum rate is controlled by the size of the processing plant that, in turn, is determined by market factors. To manage the deposit, you might want to know the origin of the lithium. For example, is it concentrated from rainfall and surface runoff over the surrounding rock that reaches the basin, or is it from an ascending deep basin brine, or is it local groundwater discharging to the basin and evaporating; and is it a fossil or an active system? Another concern would be whether there are any restrictions on the rate and volume of water withdrawal from the aquifer system. That is, would extracting the brine impact local agricultural activities or endangered species? One might also construct a hydrologic flow model of the system to account for water flux and a solute transport model to evaluate different development schemes depending on sources of solutes.

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