Wroclaw University of Science and Technology, Department of Process Engineering and Technology of Polymer and Carbon Materials, Wybrzeze Wyspianskiego 27, Wroclaw 50-370, Poland.
NTNU Norwegian University of Science and Technology, Department of Geoscience and Petroleum, Andersens veg 15a, 7031 Trondheim, Norway; Maelgwyn Mineral Services Ltd, Ty Maelgwyn, 1A Gower Road, Cathays, Cardiff CF24 4PA, United Kingdom.
Ultrason Sonochem. 2022 Mar;84:105962. doi: 10.1016/j.ultsonch.2022.105962. Epub 2022 Feb 28.
Although numerous studies have been implemented on identifying the impact of acoustic waves on mineral beneficiation, its fundamental aspects remain unclear in the literature. The present work, for the first time, systematically investigates the role of ultrasound pre-treatment (UPT) in the carbonaceous copper-bearing shale flotation. To this end, conditioning was carried out at different powers of applied ultrasound. Non-treated and UPT shale flotation tests were performed in the presence of frother (MIBC) and collector (KEX). To analyse particle surface charge variation and collector adsorption properties after application of UPT, zeta potential and ultraviolet-visible spectroscopy measurements were implemented, respectively. The generation of sub-micron bubbles due to the acoustic cavitation was characterised by laser-based particle size measurements. Shale hydrophobicity was determined using the sessile drop and captive bubble techniques. The micro-flotation results showed that the mass recovery increased by 40% at 20 W of applied ultrasonic power. The positive effect of UPT on the copper-bearing shale flotation was related to: i) generation of ultrafine bubbles due to the acoustic cavitation phenomenon and ii) the cleaning effect through transient bubble collapse. However, rigorous ultra-sonication diminished the recoverability of the sample owing to the less intensified number of ultrafine bubbles on the particle surfaces and formation of free H and OH radicals, which led to the oxidation of particle surfaces. These statements were correlated well with the observations of the zeta potential, particle size analysis and quantified ultrafine bubbles. Finally, we briefly highlighted fundamental knowledge gaps in flotation and ultrasound-related issues for future work.
虽然已经有许多研究致力于确定声波对矿物选矿的影响，但在文献中，其基本方面仍不清楚。本工作首次系统地研究了超声波预处理（UPT）在含碳铜页岩浮选中的作用。为此，在不同的超声功率下进行了条件处理。在浮选过程中使用了起泡剂（MIBC）和捕收剂（KEX），进行了未处理和 UPT 页岩浮选试验。为了分析 UPT 应用后颗粒表面电荷变化和捕收剂吸附特性，分别进行了动电位和紫外-可见光谱测量。通过基于激光的粒度测量来表征由于声空化而产生的亚微米气泡。采用液滴和俘获气泡技术来确定页岩疏水性。微浮选结果表明，在施加 20W 超声功率时，质量回收率增加了 40%。UPT 对含铜页岩浮选的积极影响与以下因素有关：i）由于声空化现象产生的超细气泡，以及 ii）通过瞬态气泡破裂进行的清洁效果。然而，严格的超声处理会降低样品的回收率，因为颗粒表面上的超细气泡数量减少，以及形成游离的 H 和 OH 自由基，这导致颗粒表面氧化。这些说法与动电位、颗粒尺寸分析和量化的超细气泡的观察结果很好地相关。最后，我们简要地强调了浮选和超声相关问题方面的基本知识差距，以供未来工作参考。
