Recovery of NORM from scales generated by oil extraction

Scales, containing naturally occurring radioactive materials (NORM), are a major problem in oil production that lead to costly remediation and disposal programmes. In view of environmental protection, radio and chemical characterisation is an essential step prior to waste treatment. This study focuses on developing of a protocol to recover Ra-226 and Pb-210 from scales produced by petroleum industry. X-ray diffractograms of the scales indicated the presence of barite-strontium (Ba0.75Sr0.25SO4) and hokutolite (Ba0.69Pb0.31SO4) as main minerals. Quartz, galena and Ca2Al2SiO6(OH)(2) or sphalerite and iron oxide were found in minor quantities. Incineration to 600 degrees C followed by enclosed-digestion and acid-treatment gave complete digestion. Using Ba-133 and Pb-210 tracers as internal standards gave recovery ranged 87-91% for Ra-226 and ca. 100% for Pb-210. Radium was finally dissolved in concentrated sulphuric acid, while Pb-210 dissolved in the former solution as well as in 8 M nitric acid. Dissolving the scales would provide better estimation of their radionuclides contents, facilitate the determination of their chemical composition, and make it possible to recycle NORM wastes in terms of radionuclides production. (C) 2015 Elsevier Ltd. All rights reserved.