Recovery of Rare Earth Elements from coal tailings from British Columbia coalfields by nano-flotation

通过纳米浮选从不列颠哥伦比亚省煤田煤尾矿中回收稀土元素

• 批准号: RGPIN-2021-03098
• 负责人: Holuszko, Maria
• 金额: $ 2.4万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742378
• 关键词: Recovery; Rare; Earth; Elements; coal

Rare Earth Elements (REEs) are a group of 17 elements in the periodic table including 15 lanthanides and two transition metals: Sc and Y. These elements are used in a wide variety of modern electronic products and green energy applications. With the emergence of new clean-energy and defense-related technologies, consumption of REEs has increased rapidly, and they have been classified as critical elements by the United States, the European Union and Canada (CREEN, 2015). Considering the myriad risks of insufficient supply to meet demand, unconventional sources of REEs are currently being assessed for future exploitation. Coal deposits with enriched concentrations of REEs have been identified across the world as potential REE resources. The extraction of REEs from US coal and its by-products has been studied using different processes such as magnetic, density and gravity-based methods, flotation, ion-exchange and leaching, but the separation technology is still in the initial stages of development, and a commercial extraction process has not yet been developed. REEs in the coal are associated with minerals that are very fine (usually less than 10 µm in size); as a result, common physical concentration methods of REE from coal are feasible due to limitations of separation efficiency by these common separation processes, including froth flotation, for such fine particles. Nano-flotation which uses nano-bubbles in froth flotation was shown to be efficient in capturing very fine particles in mineral processing applications and it is a promising method for separating REE minerals from these unconventional resources. However, it has never been studied before in the context of REE recovery from coal. Previous studies carried out in my group on the coals from British Columbia (BC) showed that most of the REEs coal report to waste streams when processed. Hence, there is an opportunity for the development of nano-flotation as a process for recovery of REEs from these rejects. My Discovery Grant research program will study the nano-flotation as a process for REE recovery from coal tailings from active coalfields in BC. Currently, close to 30mln tonnes of high-quality metallurgical coal is produced in the province, and while the processing of these coals captures most of the fine coal, a significant amount (~1-2 mln/year) is still disposed as tailings. There are number of advantages of recovering REE from coal tailings; there is no mining required, possible elimination of coal tailings if clean coal can be also recovered as a secondary product. Reutilization of coal tailings and turning them into valuable resources provides Canada with significant economic benefits, especially if the REEs could be recovered from this unconventional resource as well as there will be clear environmental benefits of reducing or even eliminating coal tailings waste. There has been no study currently undertaking this type of research in Canada.

稀土元素（ree）是元素周期表中的17种元素，包括15种镧系元素和两种过渡金属：Sc和y。这些元素广泛用于各种现代电子产品和绿色能源应用。随着新的清洁能源和国防相关技术的出现，稀土元素的消费量迅速增加，并被美国、欧盟和加拿大列为关键元素（green, 2015）。考虑到供大于求的种种风险，目前正在评估非常规稀土资源的未来开发。稀土元素富集的煤层在世界范围内已被确定为潜在的稀土资源。从美国煤及其副产品中提取稀土的研究采用了磁选法、密度法和重力法、浮选法、离子交换法和浸出法等不同的工艺，但分离技术仍处于初级发展阶段，尚未开发出商业化的提取工艺。煤中的稀土元素与非常细的矿物（通常小于10微米）相关联；因此，对于煤中细小颗粒的稀土元素，常用的物理富集方法（包括泡沫浮选）的分离效率有限，因此是可行的。纳米浮选是一种利用纳米气泡进行泡沫浮选的方法，可有效捕获极细颗粒矿物，是一种很有前途的从这些非常规资源中分离稀土矿物的方法。然而，在煤中稀土元素回收的背景下，这方面的研究尚属空白。我的小组之前对不列颠哥伦比亚省（BC）的煤进行的研究表明，大多数稀土煤在加工后会进入废物流。因此，有机会发展纳米浮选作为从这些废渣中回收稀土的过程。我的发现基金研究项目将研究纳米浮选从BC省活跃煤田的煤尾矿中回收稀土元素的过程。目前，该省生产近3000万吨优质炼焦煤，虽然这些煤的加工捕获了大部分细煤，但仍有相当数量（约1- 200万吨/年）作为尾矿处理。从尾矿中回收稀土元素有许多优点；不需要开采，如果还可以回收清洁煤作为二次产品，则可能消除煤尾矿。对煤尾矿进行再利用并将其转化为有价值的资源为加拿大提供了显著的经济效益，特别是如果可以从这种非常规资源中回收稀土元素，并且减少甚至消除煤尾矿废物将具有明显的环境效益。目前在加拿大还没有进行这类研究。