Groundwater in sedimentary basins as potential lithium resource: a global prospective study.

Electric cars will require to increase the production of lithium dramatically (up to 2 Mtons lithium equivalent carbonate per year by 2030). However, conventional hard-rock and salar mining are facing environmental and social concerns. Therefore, alternative lithium resources may help meeting the global demand for the next decades. Here, we provide a systematic analysis of published lithium concentration in about 3000 samples of groundwater from 48 sedimentary basins worldwide. The highest lithium concentrations (> 102 mg l-1) are primarily found in high salinity waters (Total Dissolved Solids > 105 mg l-1) and are in the same range as brines from the most productive salars. Conservative estimations based on fluid volume and lithium concentration in selected reservoirs indicate that these lithium resources are comparable to salars and hard-rock mines (0.1-10 Mtons lithium). Therefore, lithium in groundwater from sedimentary basins could be a significant potential resource for the next decades.

Poultry litter ash characterisation and recovery.

This paper reports a complete characterisation of poultry litter ash and its potential use as a heavy metal stabiliser. We propose a novel approach, in which the ashes deriving from municipal solid waste incineration (MSWI) are combined with poultry litter ash, rather than with coal combustion flue gas desulfurisation (FGD) residues. Heavy metals stabilisation was demonstrated by comparing the elemental concentrations in the leaching solutions of the starting raw and stabilised materials: leachable Pb and Zn showed a reduced solubility. The characterisation was conducted by total reflection X-ray fluorescence (TXRF), X-ray diffraction (XRD), micro-Raman spectroscopy and scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDX). The results showed that the poultry litter ash was Ca-, P-, K- and S-rich (>29 g/kg). It contained amorphous materials (i.e. fly ash economiser (FAECO) 73% and fly ash cyclone (FACYC) 61%) and soluble phases (e.g. arkanite and sylvite; up to 13% FAECO and 28% FACYC), as well as resilient crystalline (up to 2% of FAECO and FACYC) and amorphous phases (e.g. hydroxyapatite). After two months, the Pb and Zn concentrations in the leachate solutions were below the limit set by the European regulations for waste disposal (<0.2 mg/L and 1.5 mg/L, respectively). We propose a mechanism for the heavy metals stabilisation based on the carbonation process and high amounts of P, Ca and reactive amorphous phases. In conclusion, it is demonstrated that poultry litter ash can be an effective secondary source of heavy metals, allowing their immobilisation through P- and Ca-based reactive amorphous phases.