Innovative separation of Caesium and Strontium using flotation and magnetic particles, to convert large waste volumes into small waste packages

为了提供“低碳”能源，英国和韩国政府都制定了维持（英国）或增加（韩国计划到2022年增加59%）核能发电水平的战略。这两个国家有着悠久而成熟的民用核工业；生产需要管理的遗留遗址和材料。考虑到新建反应堆和遗留废物的需求，显然有必要制定废物管理和退役的创新方法，以安全、经济有效地解决储存和处置问题。放射性废水的处理是几乎所有核设施面临的共同而又具有挑战性的任务之一，无论是现役核电站还是退役核电站。从冷却池到燃料后处理的各种液体流需要立即处理，以减少安全排放的活动。虽然正在进行的工厂操作中的低效率清除路线可能导致陆地和海洋的长期环境积累，但移动放射性离子的突然释放可能导致严重的环境污染。在福岛等重大核事故发生后，处理大量污水的严峻困难凸显了对新的灵活技术的需求。特别是铯-137 （137Cs）和锶-90 （90Sr）的释放，由于它们的高裂变产率和显著的半衰期（t1/2 ~ 29年），引起了重大的安全和环境问题。一旦释放到生物圈中，裂变产物极有可能经历一系列最终影响人类健康的化学和地球化学过程。协助修复的方法面临着与以下方面相关的重大科学和工程挑战：1)裂变产物与环境之间复杂的相互作用；2)处理大量废物的要求。在这个英国和韩国的项目中，将研究一种基于双泡浮选和磁选的新概念来处理放射性（Cs和Sr）污染环境。将Cs+和Sr2+吸附、异质泡成核浮选、磁选减容3个阶段串联进行，将大体积废物转化为适合临时储存的小体积废物包。基于表面润湿性的浮选由于其通用性和处理大量废物的适用性而被选择为最合适的修复方法。结合流体动力空化，该工艺将能够从不需要的脉石中分离出受污染的颗粒（细粘土和磁性载体），产生泡沫，可以通过施加磁场来进一步处理，以控制泡沫的不稳定速率，而且非常重要的是控制废物包的总体体积。该研究将为开发革命性的环境污染土地（水和土壤）治理技术奠定科学基础。科学/工程方法有可能在全球退役方案和修复遗留核场址方面发展出技术进步，从而使核能的足迹不会对环境产生长期持久的影响。

Both the UK and Republic of Korea governments have a strategy to maintain (in the UK) or increase (in the ROK where capacity is planned to increase by 59% by 2022) the level of nuclear power generation in order to provide "low-carbon" energy. The two countries have a long and established civil nuclear industry; producing legacy sites and materials which will need to be managed. There is a clear imperative, given the needs of both new build reactors and legacy wastes, to develop innovative approaches to waste management and decommissioning for safe and cost effective answers to storage and disposal issues. The treatment of radioactive effluent streams is one of the common yet challenging tasks facing almost all nuclear facilities, whether active plants or decommissioning sites. Various liquid streams from cooling ponds to fuel reprocessing require immediate processing to reduce the activity for safe discharge. While low efficiency removal routes in on-going plant operations can lead to long term environmental accumulation in land and sea, the sudden release of mobile radioactive ions can lead to severe environmental contamination. The acute difficulties of treating large volumes of effluent following major nuclear incidents such as Fukushima, highlights the requirements for new flexible technology. The release of cesium-137 (137Cs) and strontium-90 (90Sr) in particular pose substantial safety and environmental concern due to their high fission yield and significant half-lives (t1/2 ~ 29 years). Once released into the biosphere there is a high potential for the fission products to undergo a series of chemical and geochemical processes that ultimately impact human health. Methods to assist in remediation face substantial scientific and engineering challenges associated with: i) complex interactions between the fission products and the environment, and ii) the requirement to process large volumes of waste. In this UK-Republic of Korea project, a new concept based on dual-bubble flotation and magnetic separation will be studied to treat radioactively (Cs and Sr) contaminated environments. The 3-stage process: i) Cs+ and Sr2+ adsorption, ii) heterogeneous-bubble nucleation and flotation, and iii) magnetic separation and volume reduction will proceed in series to transform large waste volumes into small waste packages suitable for interim storage. Surface wettability-based flotation is chosen as the most appropriate method for remediation due to its versatility and applicability for processing large waste volumes. In combination with hydrodynamic cavitation, the process will be capable of separating contaminated particles (fine clays and magnetic carriers) from the unwanted gangue to produce a froth that can be further treated by applying a magnetic field to control the rate of froth destabilization, but also and quite importantly control the overall volume of the waste package. The research will lay scientific foundation for developing revolutionary technology to treat environmentally contaminated land (aqueous and soils). The scientific/engineering approach has the potential to develop a technological step-forward for global decommissioning programmes and the remediation of legacy nuclear sites, such that the footprint of nuclear power has no long lasting impact on the environment.