Analysis of Metals in Nickel Ore

Application Note EDXRF1366

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Scope

The analysis of important metal oxides in nickel ore is demonstrated using the empirical approach.

Background

During site characterization and preparation for smelting, it is important to determine concentrations of various metals in nickel ores. While NiO and Fe₂O₃ are the most important metal oxides, TiO₂, Cr₂O₃, and MnO may also be present in significant quantities. Characterizing the ore is important to determine potential yield, as well as during extraction and smelting. EDXRF is an excellent tool for mine site exploration and characterization, and can be used throughout the processing steps, extraction, and smelting to measure the ore material, concentrate, matte, filter cakes, and slags.

NEX QC+ high-resolution EDXRF analyzerModel: NEX QC+

Calibration

20 site-specific calibration standards were supplied as pressed pellets for empirical calibration. Optimum calibration can be achieved using standards that represent the ore material at the site, where each standard is assayed for all oxides of interest and concentrations evenly span each range and vary independently. Given assays for light element oxides such as Al₂O₃, SiO₂, and SO₃, those calibrations can be made as well.

Component Concentration range (mass%) Standard error of estimate
NiO 0.06 – 3.00 0.0146
Fe₂O₃ 8 – 66 0.2306
TiO₂ 0.01 – 2.41 0.0184
Cr₂O₃ 0.04 – 3.64 0.0296
MnO 0.10 – 2.00 0.0157

Standard sample recovery and precision

Representative low, medium, and high NiO concentration calibration standards were measured 10 consecutive times each in a static position to demonstrate effective recovery and analytical precision.

Sample ID: Sample ST14
Units: Mass%
Oxide Assay value NEX QC+ average value Std. dev
NiO 2.98 3.00 0.003
Fe₂O₃ 21.71 21.89 0.02
TiO₂ --- 0.019 0.004
Cr₂O₃ 1.07 1.106 0.007
MnO 0.38 0.366 0.002

Sample ID: Sample S103
Units: Mass%
Oxide Assay value NEX QC+ average value Std. dev
NiO 1.28 1.297 0.006
Fe₂O₃ 65.63 66.19 0.07
TiO₂ 0.05 0.051 0.003
Cr₂O₃ 3.64 3.636 0.015
MnO 1.16 1.178 0.008

Sample ID: Sample 1696
Units: Mass%
Oxide Assay value NEX QC+ average value Std. dev
NiO 0.73 0.746 0.003
Fe₂O₃ 12.21 12.16 0.02
TiO₂ 0.18 0.166 0.004
Cr₂O₃ 0.32 0.322 0.003
MnO 0.20 0.190 0.001

Sample ID: Sample 1702
Units: Mass%
Oxide Assay value NEX QC+ average value Std. dev
NiO 0.26 0.257 0.001
Fe₂O₃ 12.14 12.05 0.02
TiO₂ 0.30 0.292 0.005
Cr₂O₃ 0.23 0.238 0.002
MnO 0.20 0.204 0.001

Analysis of unknown samples

Unknown samples with expected values were submitted from the mine site for measurement against the calibrations built. Results are shown below.

Sample ID NiO Fe₂O₃ TiO₂ Cr₂O₃ MnO
  Expected Mass% Measured Result Expected Mass% Measured Result Expected Mass% Measured Result Expected Mass% Measured Result Expected Mass% Measured Result
ST11 2.41 2.43 24.95 25.27 <0.01 0.03 1.21 1.31 0.38 0.38
ST16 2.04 2.05 15.37 15.32 <0.01 ND 1.23 1.22 0.22 0.25
ST20 1.79 1.76 65.45 64.96 <0.01 0.05 2.73 3.08 1.22 1.24
AP06 1.33 1.41 16.38 17.17 0.02 0.03 0.60 0.63 0.27 0.27

Conclusion

The NEX QC+ offers analysts a simple yet powerful and versatile system for quantifying elemental composition using the empirical approach. The results of this study indicate that given stable samples, proper sample handling and proper calibration technique, the Rigaku NEX QC+ EDXRF can achieve excellent results for the measurement of the key metal oxides NiO, Fe₂O₃, TiO₂, Cr₂O₃ and MnO in nickel ores. 

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