In-situ leaching (ISL), also known as solution mining or in-situ recovery (ISR), involves leaving ore in the ground, and recovering the minerals by dissolving them. The pregnant solution is pumped to the surface where minerals can be recovered. In-situ leaching is used for example for uranium mining.
Leaching agents, containing acids (i.e. sulfuric acid) or alkali mixed with oxidants (i.e. hydrogen peroxide), are pumped into the ground, returning with solved uranium. ISL wellfields vary greatly depending on local conditions such as permeability, sand thickness, deposit type, ore grade and distribution. Using on-line analysis to monitor uranium recovery, enables operators to switch between several streams of injection and extraction wells. This allows control and the possibility to steer acid consumption resulting in a constant uranium in-flux for further solvent extraction (SX). A more constant in-flux leads to reduced energy consumption and costs.
This application note demonstrates the analytical capability and stability of the Epsilon Xflow to monitor on-line the in-situ leaching of uranium from its host rock.
Measurements were performed using a Malvern Panalytical Epsilon Xflow EDXRF spectrometer, equipped with a 50 kV silver anode X-ray tube, 6 beam filters, and a high-resolution Silicon Drift Detector SDD30. The system is equipped with a flow cell, where the solution is pumped through and analyzed.
All samples were prepared out of commercially available ICP standards. 6 set up standards were made with varying SO4, U and Fe concentrations. Measurement procedure Approximately 100 ml of each samples were pumped continuously through the flow cell during analysis. The used measurement conditions are listed in table 1.
Compound | kV | μA | Medium | Filter | Meas. time (s) |
---|---|---|---|---|---|
SO4 | 9 | 1650 | Air | Ti | 60 |
Fe | 20 | 550 | Air | Al Thick | 60 |
U | 50 | 65 | Air | Ag | 60 |
Table 1. The used measurement conditions
The data presented in this application note demonstrates the capability of the Epsilon Xflow EDXRF spectrometer for real-time monitoring of in-situ leaching processes for uranium.
The results from the repeatability tests illustrate the stability and robustness of the Epsilon Xflow. The combination of excellent detector resolution, high sensitivity and powerful software deconvolution models contribute to the accuracy and precision of the results.
Malvern Panalytical offers besides the Epsilon Xflow a wide range of sample conditioning solutions for seamless integration of the Epsilon Xflow into real production process. This includes the filtering for reproducible sample representation during analysis.