The mapping and investigation of radionuclide pollution in the processing plant of a spent phosphate mine by using GIS techniques

Abstract

The mining and refinement of phosphate is characterised by high levels of uranium. An in situ gamma ray survey was done at the processing plant of a spent phosphate mine near Vredenburg on the west coast of South Africa in order to assess radionuclide concentrations. The concentrations of potassium, thorium and radioactive progeny of uranium were measured and plotted with the help of QGIS software. The results demonstrated high concentrations in specific areas of the plant. The highest concentrations were found to be 898 Bq/kg for potassium, 162 Bq/kg for ²³²Th and 639 Bq/kg for ²²⁶Ra. It was demonstrated that the refinement process technologically enhanced the naturally occurring radioactive nuclides and contaminated sections of the processing plant. The causes of the contamination were also investigated. The effective dose for the various parts of the processing plant was also estimated and the highest level was found to be 0.45 mSv/y. The article finally draws conclusions as to the environmental impact of the radiation and possible future preventative measures that could be followed in order to minimize pollution.

Keywords: Environmental pollution, GIS techniques, Gamma ray measurements, uranium, phosphate mining