FLOTATION OF RARE EARTH OXIDE MINERALS

REO Minerals There are about 250 minerals that contain REOEs, but only a few of these minerals are of any economic value. Most of them contain uranium, titanium, tantalum and niobium. Based on the composition of the REOE minerals, they are classified into two main groups The cerium group of REOEs (Light Rare Earth Elements), in which loparit, bastnaesite, parisit, monazite, eshipit and ortit are included. The yttrium group of REOEs (Heavy Rare Earth Elements), this group includes ytroparisite, fergusonite, samarskite, priorit, kenotime, gadolinite, amongst others.

REO Minerals Most of the products that come from REOEs are monazite, bastnaesite and euxenite. Monazite (Ce,La…)PO4: Monazite belongs to the phosphate group of REOEs, with low magnetic properties and bright yellow color. Usually it is found in pegmatites and granites and also entrained in zircon, magneite and ilmenite. Bastnaesite (Ce,La,Pr)[CO3]F Bastnaesite belongs to the carbonatite group of minerals that contain REOEs. In addition to cerium group of elements, it also contains yttrium and europium. Typically, it contains 65–75% REOE. Bastnaesite is usually found in pegmatites, carbonatite and hydrothermal ore bodies in alkaline gangue minerals. Because it is poor chemically and stable, it is not found in mineral sand deposits. Euxenite (Y,Ce,Ca,U,Th)(Ti,Nb,Ta)2O6 Euxenite is a titanotantalum/niobium-containing mineral It is usually found in sand deposits together with monazite, xenotime, zircon, beryl, columbite and other minerals.

Flotation of Bastnaesite Containing Ores Hydroxamic acid used as a collector has shown to give better selectivity than fatty acid. Extensive work has been carried out to evaluate different fatty acids. US Bureau of Mines (Reno, NV, USA): distilled acid gave results superior to those of linoleic acid or fatty acid containing rosin acid. University of New Mexico and Molycorp laboratory: distilled tall oil containing rosin acid gave results better than those of pure oleic acid. These differences are likely due to different flotation responses related to a variation in the mineralogy. Depressants: Quebracho, tanic acid and different lignin sulphonates. Temperature: Heating the pulp with collector is the only way to selectively float bastnaesite. Heating the pulp with collector is believed to result in selective aggregation of bastnaesite in the form of repellent droplets,

The Mountain Pass Concentrator (USA) The major REO mineral is bastaenesite with minor amounts of synchisite, parasite and monazite The major gangue minerals are calcite, barite, silicates, and dolomite P80=56 µm Soda Ash (Na2CO3): 3000-4500 g/t Sodium fluorosilicate: 300-600 g/t Lignin Sulphonate (Weslig): 2400-3500 g/t Tall oil fatty acid:200-400 g/t

Metallurgical Results

Flotation of Barite, Fluorite and Bastnaesite from Dong Pao Deposit The ore deposit is located in the Lai Chan Province of Vietnam This ore is heavily weathered ore, with more than 30% of the bastnaesite contained in the –7μm fraction. The major host minerals present in this ore are barite and fluorite. Direct flotation of bastnaesite is not possible because of high barite and fluorite content Fluorite has similar flotation properties as bastnaesite Therefore, sequential barite–fluorite–bastnaesite flotation is applied

Bastnaesite Flotation Washing and desliming Barite flotation Depressant: sodium silicate Activator: BaCl2 Collector: SR82 (petroleum sulphonate+sodium alkyl sulphate+succinamate mixture) Selective collector against fluorite and bastnaesite Flourite flotation Depressant: MESB (mixture of Quebracho and lignin sulphonate Collector: mixture of oleic acid and phosphoric ester Bastnaesite Flotation Depressants: NaCO3, Citric acid, MM4 (mixture of lignin sulphonate with MW 9000-20000) Collector: tall oil fatty acid madified with three ethylene tetra amine

Reagnet Scheme for Dong Pao Ore

Metallurgical Results