Hand Held Laser Induced Breakdown Spectroscopy Analysis for Lithium in Geological Materials

Table of Contents

Introduction
Background
Data
Elemental Mapping: Another Advantage of LIBZ Technology
The Z-200 vs Z-300
Conclusion

Introduction

The SciAps Z range of hand held laser induced breakdown spectroscopy (HHLIBS) analyzers (Figure 1) has now enabled lithium analysis in a wide variety of geological samples with field portable equipment.

The Z is probably the only HHLIBS-based analyzer in the world that can carry out geochemical analysis of samples by providing a highly accurate, fast, and largely portable method for elemental detection. It is specially designed to analyze elements with low atomic number such as B, Li, Be, Na, which cannot be studied by other field portable methods.

Figure 1. The SciAps Z range of HHLIBS analyzer

Similar to field portable XRF (fpXRF), the Z HHLIBS analyzer enables transition and heavy metals to be analyzed, and ensures enhanced performance for elements with low atomic number by eliminating the typical regulatory challenges posed by X-ray devices.

Moreover, the Z not only detects and measures lighter elements such as Li, B, Be, Na, and C that cannot be analyzed with fpXRF, but also measures Si, Mg, and Al at considerably lower detection limits than fpXRF is capable of.

The SciAps Z is ideally suited for performing in-field analysis of samples comprising lithium down to single-digit ppm concentrations. The analyzer enables lithium concentrations to be determined in the field without the need for depending on traditional laboratory analysis.

The SciAps Z can also be used to carry out quantitative multi-element analysis of samples, to generate elemental distribution maps and help better understand the distribution of key elements in geological samples.

Background

Lithium is mostly extracted from three principal natural sources:

  • Salt lake deposits and the brines associated with such deposits.
  • The recently identified silicate mineral Jadarite and sedimentary deposits comprising lithium-abundant clays such as Hectorite.
  • Hard rock pegmatite deposits that have abundant lithium-bearing minerals such as Lepidolite, Spodumene, and Zinwaldite.

In the past, salt lake deposits have contributed to a major portion of lithium production. However, the current rising demand for lithium batteries is leading to large-scale exploration into other sources of the element. Novel processing techniques are being developed to carry out economical extraction of lithium from deposits that have previously been considered sub-economic.

Data

Figure 3 illustrates the exceptional correlation between the laboratory and field measurements of lithium.

Figure 3. Correlation of field and laboratory measurements of lithium.

A simple field press (5-10 ton) was used to press the field samples in a metal holder. The resulting samples were transferred to the analyzer for 3 second tests. Several spots in the samples were tested and averaged to minimize the effects of sample non-homogeneity, thus making the total test time around 10-15 seconds.

To build the lithium calibration on the Z-300 LIBS analyzer, various geological reference samples were first analyzed. The resultant data better agreed with the laboratory results, and the detection limits were in the range of 10 ppm.

The desktop/laptop Profile Builder software integrated into the SciAps Z analyzer provides users with the ability to produce their own calibrations, to carry out different pre-processing steps, to select different lines, and to overlay spectra for comparison.

Elemental Mapping: Another Advantage of LIBZ Technology

A further special characteristic of the Z analyzer is the ability to carry out elemental mapping of cores and rocks by using the integrated camera/video and a 2-D rastered laser.

Operators can now map elemental distribution within an area of 2 x 2 mm using the SciAps GeoChem Pro Application, thus enabling them to easily make important deductions related to mineral chemistry. The Z also enables implications of changes in mineral chemistry to be used as a vectoring tool for targeting mineralization.

Figure 4a depicts the image of a rock sample under test as it appears on the Z’s display through its integrated camera. The bottom two-third section of this sample is suspected to be Lepidolite.

The elemental heat map of lithium generated by using Z’s Geochem Pro software application, illustrated in Figure 4b, confirms the presence of lithium at higher concentration in this section of the sample.

Figure 4. The image of a rock sample tested using LIBZ technology.

The Z-200 vs Z-300

The SciAps Z comes in two configurations, the Z-200 and Z-300, with respective wavelength ranges of 190-615nm and 190-950nm. The wider spectral range of the Z-300 allows the measurement of additional elements such as H, Cl, O, Br, N, F, Rb, K, S, and Ce. As a matter of fact, the wide spectral range of the Z-300 enables it to measure any element in the periodic table.

As illustrated by the spectrum in Figure 5, the Z-300 has the ability to measure both prominent lithium emission wavelengths at 610.386 and 670.809 nm. The 670 nm spectral line is nearly five times more sensitive and is the recommended one for measurements of low concentration, i.e. < 100 ppm. If users wish to measure both high and low concentrations, the SciAps calibration software can support multiple spectral lines.

Figure 5. Lithium spectrum generated using Z-300 spectrometer configuration.

Conclusion

The SciAps Z range of HHLIBS analyzers has been proven to be one of the most effective tools for performing the in-field analysis of lithium in a wide variety of geological materials. Higher accuracy levels and detection limits down to 10 ppm can be achieved with the integrated quantitative GeoChem Application.

Moreover, the qualitative GeoChem Pro Application can be used to analyze associated mineral chemistry and relative elemental distribution maps.

Click here for more information about the Z handheld LIBS analyzer from SciAps

This information has been sourced, reviewed and adapted from materials provided by SciAps, Inc.

For more information on this source, please visit SciAps, Inc.

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