Geometallurgical Characterization of Non-Ferrous Historical Slag in Western Tasmania: Identifying Reprocessing Options

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.

Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

“…Finally, it is also interesting to mention that several other constituents were found in the alkaline matrix of the AAMs produced using slag particles with median size of 11.9 µm, such as Cr (up to 22%), and Ni (10%) due to dissolution of chromite (FeCr 2 O 4 ) and awaruite (Ni 3 F) particles, respectively. Figure 11d (zoom of rectangular area of Figure 11c) shows the presence of chromite and awaruite as small single intergrown drops and inclusions embedded in the clinopyroxene (diopside) matrix as well as the development of ferrite dendrites in the fayalite matrix [2,73]. The AAMs produced using the same synthesis conditions were also characterized with XRD, as seen in Figure 12 result, higher solubilization of Si and Al from the raw slag was attained that subsequently caused the formation of denser reaction products and the increase in compressive strength, up to 60.8 MPa.…”

Recycling and Reuse of Mine Tailings: A Review of Advancements and Their Implications

“…In the mining process itself there is the formation of slag, a waste material produced in ore extraction. This mining waste can be used as construction material (road construction), both in infrastructure and in the reclamation of land damaged by mining [110,111]. However, the use of slag from metallurgical processes is more common for the recovery/recycling of tailings from mining, so steel slag is among the more commonly used waste types [32,74,112].…”

Effect of Thiourea on Lead Release from Lead-Bearing Jarosite under Freeze–Thaw Cycling

“…In China alone, it has been reported that more than 30 million tons of jarosite residue has been accumulated, with an increasing trend year by year, which poses a significant potential threat to the environment [4,5]. Some zinc hydrometallurgy plants store the jarosite residue in nearby construction slag yards, resulting in a large land footprint and significant environmental pollution risks [6,7]. Hage et al [8] employed slag yard stockpiling to address the leakage issues of two jarosite residue ponds at the Budelco Zinc Plant in the Netherlands.…”