Development of a Portable Li-K Analyzer and Its Application in the Determination of Lithium in Spodumene

Most of the mineral resources of lithium and potassium are distributed in remote western China. Fast, on-site analytical techniques are urgently needed for their exploration and comprehensive utilization. In this work, a newly developed portable Li-K analyzer was introduced for its analytical performance and the application of this equipment in determining lithium in spodumene is also discussed. The analyser is a type of atomic emission spectrometer based on solution cathode atmospheric glow discharge. Sample solution was used as a graphite cathode, which atomized and excited the elements Li and K. A charge coupled device (CCD) was used to detect the characteristic lines of Li and K, which had wavelengths ranging from 345 to 1015 nm with a 3 nm resolution. Using a Li analytical line of 670.78 nm and a K analytical line of 769.90 nm under the optimized working conditions, the measurement precisions for Li and K were greater than 2%RSD with the limit of detection of 0.03 μg/mL. Results show that different types and concentrations of acids strongly affect the intensities of Li and K, and co-existent elements produce serious matrix effect. Quantification of Li in spodumene ores by use of a calibration curve without matched matrix could not produce accurate results with relative standard deviation up to 267%. Standard addition methods can eliminate the influence of the matrix effect and obtain analytical results consistent with those by Inductively Coupled Plasma-Optical Emission Spectrometry, which thus provides a basis for on-site determination of Li in solid samples.