Formation of Ta-rich magnetite phases in WEEE recycling slags through modification and controlled cooling

通过改性和控制冷却在 WEEE 回收渣中形成富钽磁铁矿相

• 批准号: 470553874
• 负责人: Professor Dr.-Ing. Bernd Friedrich
• 金额: --
• 依托单位: Institut für Metallurgische Prozesstechnik und Metallrecycling (IME)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/470553874?language=en
• 关键词: Formation; Ta; rich; magnetite; phases

During the last decades, the evolution of electronic devices push up the consumption of elements like Ta, In, Te, Ga, Se, and several Rare Earth Elements (REE), having a scarce presence in the technosphere. In most cases, the use of these strategic elements is in ppm, and thus, their recovery rate is smaller than 1%. Today, extract these raw materials from Waste Electrical and Electronic Equipment (WEEE) is one of the big challenges of process metallurgy. Typically found in pyrometallurgical slags from WEEE treatment, they are not recovered as their low concentration makes them economically unsuitable for further extraction under the conventional state of the art. Besides their scarcity, natural sources are found outside European borders and, due to their technological importance, are declared as Critical Raw Materials (CRM) by the European Union.Nonferrous metallurgy utilises fayalitic slag to treat several metal scraps such as lead, copper and WEEE because of their low viscosity, melting point and iron immobilisation in the slag. During cooling, fayalite partially decomposes into magnetite and silica. Magnetite share is inverse spinel structure with other compounds that under specific conditions show a magnetic behaviour and can be recovered using magnetic separators. Several authors have reported these strategies to concentrate Fe, Ti and V.This project aims to understand the formation and growing mechanism of artificial magnetitic mineral to concentrate and selectively capture CRM, focusing on Tantalum from WEEE. This phenomenon is strongly affected by the process conditions such as liquidus temperature, cooling rates, oxygen partial pressure in the melt, as well as the oxidation state of different ions in the slag. These different phenomena control the segregation and precipitation of Fe inversed spinel phases from fayalite and capturing several valuable elements during this process. The generation of data for modelling and setting the thermo-physical properties such as viscosity and density in a temperature-dependent system improves the possibilities to achieve control over the formation of the targeted structures.

在过去的几十年中，电子设备的发展推动了Ta，In，Te，Ga，Se和几种稀土元素（REE）等元素的消费，这些元素在技术领域中很少存在。在大多数情况下，这些战略元素的使用量以ppm计，因此，其回收率小于1%。如今，从废弃电气和电子设备（WESTERN）中提取这些原材料是工艺冶金的一大挑战。通常存在于来自湿法冶金处理的火法冶金炉渣中，由于其低浓度使得其在经济上不适合在传统技术水平下进一步提取，因此无法回收。除了稀缺性之外，天然来源在欧洲边界之外，由于其技术重要性，被欧盟宣布为关键原材料（CRM）。有色金属冶金利用铁橄榄石渣处理几种金属废料，由于它们的低粘度、熔点和铁在炉渣中的固定性，在冷却过程中，铁橄榄石部分分解成磁铁矿和二氧化硅。磁铁矿部分是与其他化合物的反尖晶石结构，在特定条件下显示出磁性行为，可以使用磁选机回收。几位作者已经报道了这些策略，以集中铁，钛和V。本项目旨在了解人工磁铁矿的形成和生长机制，以集中和选择性地捕获CRM，重点是钽从钨。这种现象受到工艺条件的强烈影响，例如液相线温度、冷却速率、熔体中的氧分压以及炉渣中不同离子的氧化态。这些不同的现象控制了铁橄榄石中铁反尖晶石相的分离和沉淀，并在此过程中捕获了一些有价值的元素。生成用于建模和设置热物理性质（例如，温度依赖性系统中的粘度和密度）的数据提高了实现对目标结构的形成的控制的可能性。