Gold Processing

Application Note XRT1336

xrt1336 gold banner


On-line analysis of gold in impregnated stripping solutions during the electrowinning process is demonstrated.


Gold ore processors commonly utilize the cyanide leaching technique to recover trace gold content. After the gold is leached out of the ore, it is typically absorbed onto activated carbon in processes such as Carbon-in-Pulp (CIP), Carbon-in-Leach (CIL), or Carbon Column (CC). Once absorbed, the gold is stripped from the carbon and the impregnated stripping solution fed into the electrowinning process where the gold is recovered by electrolysis. By measuring the gold in the stripping solution real-time, operations can trend when the solution will be barren of gold, significantly improving the plant’s efficiency.

The Rigaku NEX OL offers a simple and low maintenance on-line analytical technique for trending such solutions. Results are communicated to your plant DCS (distributed control system) via 4 – 20 mA current loops or MODBUS® over Ethernet connection allowing for real time closed loop control.



A simple linear empirical calibration was built using a suite of four calibration standards assayed by AA. Calibration can be made in units of ppm or troy oz/ton.

Element: Au  
Units: troy oz/ton  
Sample I.D. Assay value Calculated value
2 0.058 0.067
6 0.174 0.174
23 0.667 0.638
41 1.189 1.204
Element: Au  
Units: ppm  
Sample I.D. Assay value Calculated value
2 2.0 2.3
6 6.0 6.0
23 23.0 22.0
41 41.0 41.5

XRT1336 Correlation plot Au troy
XRT1336 Correlation plot Au ppm


Instrument repeatability (precision) is determined by ten repeat analyses of a sample in static position. Precision results are summarized here.

Element: Au    Units: troy oz/ton
Sample Standard value Average value Std. dev
6 0.174 0.145 0.012
23 0.667 0.632 0.020
Element: Au    Units: ppm
Sample Standard value Average value Std. dev
6 6.0 5.0 0.4
23 23.0 21.8 0.7

NEX OL features and benefits

  • XRT1306 screenReal-time process control
  • Trend analysis charting
  • 50 kV X-ray tube excitation source with high resolution and count rate silicon drift detector (SDD) technology
  • Industrial touchscreen user interface
  • Unique toolless flow cell design
  • 4 – 20 mA or MODBUS® over Ethernet results reporting


The NEX OL offers real-time trend analysis in a simple yet powerful and versatile system for quantifying the elemental composition of a process stream. The results of this study indicate that given stable samples, proper sample handling and proper calibration technique, the Rigaku NEX OL EDXRF can achieve excellent results in monitoring the concentration of gold strip solutions as part of the electrowinning process.

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