Analysis of fused beads of iron ore

							SPECTROLASER APPLICATION EXAMPLE

Analysis of fused beads of iron ore
Background
The preparation of inorganic materials for elemental analysis often involves dissolution of the material at high-temperatures in the presence of a fluxing compound such as lithium tetraborate. In the case of XRF analysis, the high-temperature melt is most often cast into a fused bead /disc which is then placed in the instrument for analysis. In the case of AAS and ICP analysis, the fused material would be dissolved in acid and the solute used in the instrument to obtain the analysis. Fused bead analysis is a commonly applied standard method for the analysis of iron ore. The current tests are designed to test the efficacy of the Spectrolaser in the analysis of fused beads and hence gauge the suitability of the Spectrolaser in this format of iron ore analysis. In these tests, three fused beads were prepared from a synthetic iron ore standard using the following mixture ratios: 1. 0.66g synthetic Fe ore : 6.800 grams flux 2. 0.33g synthetic Fe ore : 7.13 grams flux 3. 0.165 g synthetic Fe ore : 7.295 grams flux The flux used in each case was 12:22 x-ray flux containing 35% lithium tetraborate and 65% lithium metaborate. Shown below are examples of the fused beads.

The elemental composition of the resulting fused beads is shown in the Appendix.

ANALYSIS METHOD
The fused beads were placed in the Spectrolaser 7000 (0.04 nm resolution) and analysed without any additional sample preparation.

Spectrolaser operating conditions Laser Energy : Gate Delay : Scan Distance : Grid lines : Number of Laser pulses per grid line : Total number of analysis points: Analysis Atmosphere: Full Analysis Time:

300mJ 1 microsecond 16 mm 3 25 75 Air 30 seconds

All measurements were performed without buffer gas, i.e. the analysis atmosphere was laboratory air.

DETECTABLE ELEMENTS
Detectable elements include: Al, As, Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Na, Ni, N, O, P, Pb, Si, Sr, Ti, V and Zn

RESULTS
The Spectrolaser uses a technique known as Laser Induced Breakdown Spectroscopy (LIBS) to perform the elemental analysis of materials. Calibration involves the use of certified reference materials, the selection of an appropriate elemental optical emission line, and, in most cases, selection of a normalization emission line. The Spectrolaser software automatically constructs calibration curves of the normalised peak area vs elemental concentration present in the reference materials. The concentration is determined in samples of unknown composition by the instrument using comparison with this calibration reference. In these tests the linearity of the emission lines is investigated for each observed element.

Calibration curves for key elements
Oxide % (Fe, Si, Al, P, Ca, Ti, Mg, K)

Calibration Curves – Oxide ppm (Mn, V, Sn, Cr, Co, Ni, Cu, Zn, As, Ba, Na)

Appendix
Dilution Factor
Raw Analysis Disc 1 Disc 2 Disc 3 1 0.088 0.044 0.022

Fe2O3
64.02 5.66 2.83 1.42

SiO2
7.12 0.63 0.31 0.16

Al2O3
4.99 0.44 0.22 0.11

P2O5
2.63 0.23 0.12 0.06

CaO
4.26 0.38 0.19 0.09

TiO2
1.5 0.13 0.07 0.03

Mn3O4
19368 1713.52 856.76 428.38

MgO
5.03 0.45 0.22 0.11

K2O
1.828 0.16 0.08 0.04

SnO2
1955 172.96 86.48 43.24

SnO2 Raw Analysis Disc 1 Disc 2 Disc 3
1955 172.96 86.48 43.24

V2O5
1930 170.75 85.38 42.69

Cr2O3
2109 186.59 93.29 46.65

Co3O4
1985 175.62 87.81 43.90

NiO
1931 170.84 85.42 42.71

CuO
1908 168.8 84.40 42.20

ZnO
1955 172.96 86.48 43.24

As2O3
1121 99.18 49.59 24.79

PbO
1926 170.40 85.20 42.60

BaO
1944 171.99 85.99 43.00

Na2O
11403 1008.84 504.42 252.21