Characterization and Beneficiation Options for Tungsten Recovery from Yxsjöberg Historical Ore Tailings

Jane Mulenshi,Jan Rosenkranz,Pourya Khavari,Saeed Chehreh Chelgani

doi:10.3390/pr7120895

Abstract

Repositories of historical tungsten mining tailings pose environmental risks, but are also potential resources for valuable metals. They still contain large tonnages of useful minerals and metals, reflecting the inefficient extraction methods and/or low metal prices at the time they were mined. The focus of this study is to evaluate the technical viability of reprocessing the tailings to recover some of the contained valuable minerals and metals, as well as reducing the negative environmental impact associated with the tailings. Geometallurgical studies were conducted on drill core samples taken from the Smaltjärnen tailings repository of the closed Yxsjöberg tungsten mine, Sweden. The collected samples were characterized physically, chemically, and mineralogically. Knelson concentrator dry low- and high-intensity magnetic separation methods were tested as potential beneficiation methods. The tailings are dominated by the −600 to +149 µm particles. The highest concentration of tungsten (W) was 0.22% WO3. Using a Knelson concentrator, scheelite (main W mineral) recovery was enhanced, with 75 wt.% tungsten recovered in the 34 wt.% heavy concentrate. Only 1.0 wt.% sulphur (S) reported to the non-magnetic fraction. Based on the findings, a methodology and a preliminary process flowsheet for reprocessing the tailings is proposed.

Highlights

Tungsten (W) is among the critical raw materials with significant economic importance and high supply risk for the European Union [1]
Historical tailings (HT) recycling is being considered as a supply risk-reducing measure [1]
The analyses showed that pyrrhotite was the main Fe–sulphide mineral responsible for acid mine drainage (AMD) and need to be sequestered from the bulk tailings as a remediation measure

Summary

Introduction

Tungsten (W) is among the critical raw materials with significant economic importance and high supply risk for the European Union [1]. Tungsten is produced from scheelite and wolframite ores with 0.08–1.5% tungsten trioxide (WO3 ) [3]. These tungsten minerals are friable in nature compared to the associated gangue minerals; fine tungsten particles are excessively generated during the necessary comminution processes. For critical raw materials with a high supply risk such as tungsten, old tailings storage facilities (TSF) are potential sources for additional production. There is need for a holistic reprocessing approach in which the valuable minerals will be recovered, and the environmental risk will be reduced, leaving an inert and environmentally safe residue [7]

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Conclusion