Processing a rare earth mineral deposit using gravity and magnetic separation Adam Jordens a,⇑ , Richard S. Sheridan b , Neil A. Rowson c , Kristian E. Waters a a Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada b School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom c School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom article info Article history: Available online xxxx Keywords: Rare earth minerals WHIMS Knelson Concentrator Falcon Concentrator Vibrating sample magnetometer abstract Rare earth (RE) mineral deposits are typically processed using several different unit operations including flotation, gravity, magnetic and electrostatic separation techniques. Two of the most important benefici- ation techniques for RE minerals are gravity and magnetic separation. Many RE minerals are found along- side low specific gravity gangue minerals thereby permitting the use of gravity separations to concentrate the heavy value RE minerals. Magnetic separation is used primarily to remove ferromagnetic gangue min- erals as well as to separate individual paramagnetic rare earth minerals. This work investigated the use of a wet high intensity magnetic separation (WHIMS) in conjunction with gravity pre-concentration steps (Knelson and Falcon centrifugal concentrators) to beneficiate a rare earth ore. The results of these separation steps are related to the magnetic properties of RE minerals, based on literature and measurements conducted using a vibrating sample magnetometer (VSM). Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction 1.1. Rare Earth minerals Rare earth (RE) element bearing minerals are composed of at least one of the fifteen lanthanide elements or yttrium. Rare earth elements are used in a diverse range of applications including high strength magnets, phosphors, alloying elements, catalysts and pol- ishing compounds (Crow, 2011; Meyer and Bras, 2011; Preinfalk and Morteani, 1986). There are many different RE minerals and these minerals can be found in many locations throughout the world; the bulk of currently operating RE mines are located in China. Recently, the Chinese government has begun imposing strict ex- port quotas on the RE industry thereby driving RE exploration and mine development in many other regions of the world (Chen, 2011). The three most common RE minerals mined are bastnäsite, monazite and xenotime, however the new deposits under develop- ment contain many new minerals with unknown characteristics. Most RE mineral deposits are beneficiated through a combination of unit operations such as gravity concentration, magnetic separa- tion and froth flotation (Zhang and Edwards, 2012). Due to their relatively high specific gravities (between 4 and 7) gravity separa- tion can be used to concentrate RE minerals by eliminating low specific gravity gangue minerals such as quartz (Ferron et al., 1991). In the context of RE mineral beneficiation, magnetic separa- tion is typically used for two purposes: low intensity magnetic sep- aration is used to remove ferromagnetic gangue minerals such as iron oxides and high intensity magnetic separation is used to sep- arate monazite and xenotime from other heavy minerals (Gupta and Krishnamurthy, 1992). For further information on rare earth physical beneficiation re- cent reviews by Zhang and Edwards (2012) and Jordens et al. (2013a) should be consulted. 1.2. Gravity separation Gravity separation is used in mineral processing to separate minerals based on differences in specific gravity. The most com- mon and successful type of gravity separator used for fine particle sizes is a centrifugal gravity concentrator (Falconer, 2003). These separators introduce a mineral slurry into a rapidly rotating bowl to generate centrifugal forces on the particles that are much higher than the force of gravity and therefore decrease the lower size limit for effective gravity separation (Falconer, 2003). The centrifugal forces on the particles trap high specific gravity material against the sides of the bowl to become the gravity concentrate while low- er specific gravity material is carried along with the flowing fluid to report to the gravity tailings (Falconer, 2003). These concentrators are operated in a semi-continuous mode where the accumulated 0892-6875/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mineng.2013.09.011 ⇑ Corresponding author. Tel.: +01 5143984755X09503. E-mail address: adam.jordens@mail.mcgill.ca (A. Jordens). Minerals Engineering xxx (2013) xxx–xxx Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng Please cite this article in press as: Jordens, A., et al. Processing a rare earth mineral deposit using gravity and magnetic separation. Miner. Eng. (2013), http://dx.doi.org/10.1016/j.mineng.2013.09.011