Mineral Processing of Eudialyte Ore from Norra Kärr

Abstract

Eudialytes are a nonconventional source for rare earth elements (REE). As the total REE content of eudialytes is relatively low, high-grade mineral concentrates have to be produced. The applicability of magnetic separation and direct selective flotation for the processing of eudialyte ore from Norra Kärr (Sweden) was tested. The eudialyte in the used sample contains around 4 % of REE. Magnetic separation is applicable for eudialyte ore processing. The higher the strength of the magnetic field, the higher the recovery. Recovery of around 81 % of REE was achieved in a two-stage process of rougher and scavenger at a mass reduction of 48 %. The concentrate grade of around 0.76 % REE is not sufficient for further hydrometallurgical processing steps. A newly developed reagent regime for the direct selective flotation of eudialyte from eudialyte ore was tested with different samples. The regime consists of oxalic acid and sodium hexametaphosphate as depressants and a mixture of mono/di phosphoric acid esters as collector, at a pH below 4. This new method proved applicable for raw ore as well as magnetic preconcentrate. Concentrates with grades of around 2 % R Y, Ce, La were produced.

The Rare Earth Elements: Demand, Global Resources, and Challenges for Resourcing Future Generations

“…Although eudialyte has a relatively low total REE content, it has a higher ratio of Nd, Pr and Dy to La and Ce, as well as low U and Th contents, which make it potentially interesting for exploitation. Recent research has investigated options for beneficiation of eudialyte, and for hydrometallurgical methods to recover the REE without formation of silica gel (Stark et al 2016;Davris et al 2016b;Voßenkaul et al 2016). The granitic and syenitic magmatic-hydrothermal deposits, such as Strange Lake, may have the potential to produce good quantities of Nd and Dy without oversupply of La and Ce, but the reality is that their complex mineralogy makes them significantly less attractive in terms of REE beneficiation.…”

Environmental Impacts of Rare Earth Mining and Separation Based on Eudialyte: A New European Way

“…In the single-stage flotation cell, the ore is enriched from 0.59% TREO to 2.69% TREO in the concentrate with a yield of 62%. The type and amount of flotation chemicals (oxalic acid, Na 3 PO 4 , H 2 SO 4 and Flotinor SM15 ® ) are identified in experiments [28]. The energy demand for magnetic separation [43] and flotation [44] are calculated by means of product information of supplier.…”

“…Separation of ferrous magnetite is carried out by low and high power magnetic separation. The ore pulp of magnetic separation passes through a multi-stage flotation resulting in a bastnasite and monazite concentrate with 55.6% and 34.1% REO, respectively [28]. The yields for bastnasite and monazite concentrate amount to 12.6% and 6%, respectively [58].…”

“…Several specific studies have proven this approach [28][29][30][31]. Besides the desired reduction of economic dependency from a Chinese supply, also environmental advantages can be achieved by replacing the production route.…”

“…Many of the data for the eudialyte process chain are based on laboratory experiments or modeling from project partners at RWTH Aachen University [28][29][30][31]. Basic process data for Bayan Obo are collected from the literature and are validated in a sound evaluation by experts from RWTH Aachen University.…”