Abstract
Pyrometallurgical processing of ore from the Zeehan mineral field was performed intermittently between 1896 and 1948, primarily recovering Pb, Ag and Cu. While Zn recovery was attempted at the time, it was unsuccessful using the available technology. Consequently, Zn reported to the slag during the smelting process. Today, the former smelter site consists of two large slag piles (North and South). Using a range of techniques (including X-ray diffractometry, scanning electron microscopy, laser ablation inductively coupled plasma mass spectrometry, and static testing) the geometallurgical and geo-environmental properties of these slag materials (n = 280) were determined. The South and North piles contain on average 15% and 11% Zn, respectively. A range of complex mineral phases were identified, and are dominated by glass, silicates (i.e., monticellite–kirschsteinite and hardystonite), oxides (gahnite and hercynite) and minor sulfides (sphalerite and wurtzite). Microtextural examinations defined nine mineral phases (Glass A, Silicates A to D, Oxides A and B, Sulfides A and B). Zn was concentrated in Sulfide A (26%), Glass A (24%) and the Silicates (43%), while Pb was concentrated in Oxide B (76%), with Sulfide B host to the highest Ag (45%) and Cu (65%). Considering this, recovery of Zn using conventional hydrometallurgical processes (i.e., sulfuric acid leaching) is suitable, however the application of unconventional biohydrometallurgical techniques could be explored, as well re-smelting. These slag materials are classified geo-environmentally as potentially acid forming, with leachate concentrations of Zn, Pb consistently above ANZECC (2000) aquatic ecosystem 80% protection guideline values, and, for the majority of samples, exceedances of Cu, Ni and Cd were also measured. Considering these findings, reprocessing of these historic slags for Zn extraction may provide an economically feasible management option for rehabilitating this historical site.
Highlights
Questions are being posed regarding how the global community can sustainably support humanity’s growing need for resources, and how waste created in the process should be handled [1]
26% (North pile) and 32% (South pile) of phases did not contain Zn in their crystal structure. This does not preclude them from being Zn hosts, as during pyrometallurgical processing, there is potential for Zn incorporation into the lattice, as described in References [8,31], where Zn substitution for Fe in olivine, spinel and pyroxene is reported
Metal liberation and sulfide oxidation from mine wastes can lead to the production and dispersal of AMD, its impacts and other metal transport mechanisms presenting significant management challenges at abandoned or historic mine and mineral processing sites
Summary
Questions are being posed regarding how the global community can sustainably support humanity’s growing need for resources, and how waste created in the process should be handled [1]. While there is a general trend of improved sustainable management in most modern mining operations (as stricter environmental guidelines and planning are in place [5]); issues still arise at historic and legacy mines or processing sites which contain mine and smelting waste. These present geo-environmental risks to the surrounding environment and can persist for decades, if not centuries, if not adequately rehabilitated. This is performed reactively (i.e., with efforts concentrated on treating the pathway or receptor)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call