The Uranium Ore Discriminator (UOD-ASLSC) measures the gamma radiation emitted by a uranium-ore truck load and establishes the average uranium-ore grade on the truck so that ore can be stockpiled more accurately within a required ore-grade range.
As truck-load tonnage differs from truck to truck, the distance-monitoring probe is used to correct the measured gamma count rate for the distance between the gamma detector and the top surface of the uranium-ore load. As a result, the UOD-ASLSC is more accurate than conventional UODs.
How it works
The RDS Uranium Ore Discriminator (UOD) is based on the detection of the gamma radiation emitted by the truck load of uranium ore. The gamma-detection system consists of eight independent gamma-detection units (four left GDUs and four right GDUs). The gamma detectors in each GDU are shielded by lead to minimise the local gamma background.
The Discriminator Control Panel (DCP) displays the gamma count of the four left and four right GDUs in 10 s, 20 s or 30 s counting windows, along with the measured average U₃O₈ concentration. The ore grade is calculated from the net truck gamma count: the left-GDU and right-GDU background counts that are programmed into the DCP memory are automatically subtracted from the left- and right-GDU “truck” signal counts.
Because trucks haul different loads of U-ore, the distance from the top of the U-ore load to the GDUs varies — the measured gamma count rate is affected by that distance. Computer modelling was used to obtain a function describing the dependence of the gamma count rate on the distance of the load from the GDUs. The ultrasonic distance-monitoring probe incorporated in the system measures the distance between the top surface of the U-ore load and the GDUs, so the measured count can be corrected and the uranium-ore grade on each truck can be estimated more accurately.
When the truck parks on the pad under the GDUs, the truck driver pushes a button on a panel inside the truck cabin. This initiates the gamma counting. When counting is finished, the DCP displays the total left and right counts and the estimated ore grade. The truck number, the ore grade (% U₃O₈), and the ore-grade cut-off are reported via radio connectivity to the operator room and to the truck driver.
Technical parameters
Operational parameters of the UOD with 16 GRDs:
- Lowest limit of detection (depends on the gamma background of the UOD pad): typically 20 ppm U₃O₈.
- Maximum measured ore grade: about 90 000 ppm U₃O₈.
- Accuracy of the measured ore grade: better than ±5 %.
- The RDS UOD is nearly temperature-independent between −10 °C and +50 °C.
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