Production of radionuclide-free copper concentrates is dependent on understanding and controlling the deportment of daughter radionuclides (RNs) produced from 238U decay, specifically 226Ra, 210Pb, and 210Po. Sulfuric acid leaching is currently employed in the Olympic Dam processing plant (South Australia) to remove U and fluorine from copper concentrates prior to smelting but does not adequately remove the aforementioned RN. Due to chemical similarities between lead and alkaline earth metals (including Ra), two sets of experiments were designed to understand solution interactions between Sr, Ba, and Pb at various conditions. Nanoscale secondary ion mass spectrometry (NanoSIMS) isotopic spatial distribution maps and laser ablation inductively coupled-plasma mass spectrometry transects were performed on laboratory-grown crystals of baryte, celestite, and anglesite which had been exposed to different solutions under different pH and reaction time conditions. Analysis of experimental products reveals three uptake mechanisms: overgrowth of nearly pure SrSO4 and PbSO4 on baryte; incorporation of minor of Pb and Ba into celestite due to diffusion; and extensive replacement of Pb by Sr (and less extensive replacement of Pb by Ba) in anglesite via coupled dissolution-reprecipitation reactions. The presence of H2SO4 either enhanced or inhibited these reactions. Kinetic modelling supports the experimental results, showing potential for extrapolating the (Sr, Ba, Pb)SO4 system to encompass RaSO4. Direct observation of grain-scale element distributions by nanoSIMS aids understanding of the controlling conditions and mechanisms of replacement that may be critical steps for Pb and Ra removal from concentrates by allowing construction of a cationic replacement scenario targeting Pb or Ra, or ideally all insoluble sulfates. Experimental results provide a foundation for further investigation of RN uptake during minerals processing, especially during acid leaching. The new evidence enhances understanding of micro- to nanoscale chemical interactions and not only aids determination of where radionuclides reside during each processing stage but also guides development of flowsheets targeting their removal.

中文翻译：

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钡，锶和铅在氯化物和硫酸盐浸出溶液中的相互作用。

不含放射性核素的铜精矿的生产取决于对238U衰变（特别是226Ra，210Pb和210Po）衰变产生的子代放射性核素（RNs）的理解和控制。目前，奥林匹克水坝加工厂（南澳大利亚州）采用硫酸浸出法，在冶炼之前从铜精矿中去除U和氟，但不能充分去除上述RN。由于铅和碱土金属（包括Ra）之间的化学相似性，设计了两组实验来了解Sr，Ba和Pb在各种条件下的溶液相互作用。在实验室生长的重晶石晶体上进行了纳米级二次离子质谱（NanoSIMS）同位素空间分布图和激光烧蚀电感耦合等离子体质谱样条，在不同的pH和反应时间条件下暴露于不同溶液中的天青石和角铁。对实验产物的分析揭示了三种摄取机制：重晶石上几乎纯SrSO4和PbSO4的过度生长；由于扩散而将微量的Pb和Ba掺入天青石中; 通过耦合的溶出-再沉淀反应在角位中用Sr广泛取代Pb（用Ba不太广泛地用Ba取代Pb）。H 2 SO 4的存在增强或抑制了这些反应。动力学建模支持实验结果，显示出将（Sr，Ba，Pb）SO4系统外推到RaSO4的潜力。通过nanoSIMS直接观察晶粒尺寸元素的分布，可以通过构建针对Pb或Ra或理想情况下所有不溶性硫酸盐的阳离子替代方案，来帮助理解控制条件和替代机制，这可能是从精矿中去除Pb和Ra的关键步骤。实验结果为进一步研究矿物加工过程中尤其是酸浸过程中RN吸收提供了基础。新证据加深了对微米至纳米级化学相互作用的理解，不仅有助于确定每个处理阶段中放射性核素的位置，而且还指导着针对去除核素的流程图的开发。实验结果为进一步研究矿物加工过程中尤其是酸浸过程中RN吸收提供了基础。新证据加深了对微米到纳米级化学相互作用的理解，不仅有助于确定每个加工阶段放射性核素的位置，而且还指导着针对去除放射性核素的流程图的开发。实验结果为进一步研究矿物加工过程中尤其是酸浸过程中RN吸收提供了基础。新证据加深了对微米至纳米级化学相互作用的理解，不仅有助于确定每个处理阶段中放射性核素的位置，而且还指导着针对去除核素的流程图的开发。