Abstract Uranium- and thorium-bearing base metal mineral deposits contain daughter radionuclides which must be monitored and preferably removed or reduced during the process of generating base metal sulfide concentrates. Understanding the behavior of these radionuclides (focusing on 226Ra in this study) is critical for minimizing their concentrations in final economic products. To this end, Ra uptake into Sr, Ba, and Pb sulfates was evaluated experimentally under various conditions, including those approximating processing plant environments. Lead activity was also monitored, as 210Pb is also a radionuclide of concern. To simplify experiments, synthetic crystals of celestine (SrSO4), baryte (BaSO4), and anglesite (PbSO4) were grown in silica gel and subsequently exposed to RaCl2 solution at both low and neutral pH, for both 40 and 210 h. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) transects were performed across the grains to determine uptake of Ra (as well as trace Sr, Ba, and Pb) in the sulfates. Results indicate that Ra uptake in celestine is efficient when Ba and Pb are absent but is reduced to nearly zero when competing with baryte and anglesite. High acid sulfate activity inhibits uptake. Baryte incorporates significant Ra under all conditions. Anglesite is affected by coupled dissolution-reprecipitation mechanisms, resulting in dissolution of PbSO4 followed by precipitation of a mixed (Pb,Ba,Sr,Ra)SO4 phase in its place. Again, high sulfate activity inhibits this reaction. With this knowledge, it may be possible for process engineers to purposefully stimulate precipitation of Ra (and possibly Pb) onto a sulfate matrix, given the right conditions. Precipitation of RaSO4 (and 210PbSO4) onto a removable phase during processing would result in sulfide concentrates with natural background concentrations of radionuclides. Results from this study, including semi-quantitative Ra concentration data obtained via in situ LA-ICP-MS analysis add to data pertinent to management of Ra in boiler scales, oil and gas pipelines, environmental remediation, nuclear medicine, nuclear fuel processing and waste storage, among other industrial and research applications.

中文翻译：

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硫酸浸出过程中锶、钡和硫酸铅中快速、有竞争力的镭吸收

摘要 含铀和钍的贱金属矿床包含子体放射性核素，在生产贱金属硫化物精矿的过程中必须对其进行监测并最好去除或减少这些子放射性核素。了解这些放射性核素的行为（在本研究中重点关注 226Ra）对于最大限度地降低它们在最终经济产品中的浓度至关重要。为此，在各种条件下，包括那些接近加工厂环境的条件下，对 Sr、Ba 和 Pb 硫酸盐的 Ra 吸收进行了实验评估。铅活动也受到监测，因为 210Pb 也是一种令人担忧的放射性核素。为了简化实验，天青石 (SrSO4)、重晶石 (BaSO4) 和角铁矿 (PbSO4) 的合成晶体在硅胶中生长，随后在低和中性 pH 值下暴露于 RaCl2 溶液中 40 和 210 小时。对晶粒进行激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 横切面，以确定硫酸盐中 Ra（以及痕量 Sr、Ba 和 Pb）的吸收。结果表明，当 Ba 和 Pb 不存在时，天青石中的 Ra 吸收是有效的，但与重晶石和角铁矿竞争时，Ra 吸收减少到几乎为零。高酸性硫酸盐活性抑制吸收。重晶石在所有条件下都包含显着的 Ra。Anglesite 受耦合溶解-再沉淀机制的影响，导致 PbSO4 溶解，随后混合 (Pb、Ba、Sr、Ra)SO4 相在其位置沉淀。同样，高硫酸盐活性会抑制该反应。有了这些知识，在合适的条件下，工艺工程师有可能有目的地促进 Ra（可能还有 Pb）沉淀到硫酸盐基质上。在加工过程中将 RaSO4（和 210PbSO4）沉淀到可去除的相上会导致硫化物浓缩物具有放射性核素的天然本底浓度。这项研究的结果，包括通过原位 LA-ICP-MS 分析获得的半定量 Ra 浓度数据，增加了与锅炉秤、石油和天然气管道、环境修复、核医学、核燃料加工和废物中 Ra 管理相关的数据存储，以及其他工业和研究应用。