Sequential Bioleaching of Pyritic Tailings and Ferric Leaching of Nonferrous Slags as a Method for Metal Recovery from Mining and Metallurgical Wastes

Abstract

In this work, we proposed a method for biohydrometallurgical processing of mining (old pyritic flotation tailings) and metallurgical (slag) wastes to recover gold and other nonferrous metals. Since this processing allows the removal of toxic metals or at least decreases their content in the solids, this approach may reduce the negative environmental impacts of such waste. The proposed process was based on pyritic tailings’ bioleaching to recover metals and produce leach liquor containing a strong oxidizing agent (ferric sulfate) to dissolve nonferrous metal from slag. This approach also allows us to increase concentrations of nonferrous metals in the pregnant leach solution after pyritic waste bioleaching to allow efficient extraction. The old pyritic tailings were previously leached with 0.25% sulfuric acid for 10 min to remove soluble metal sulfates. As a result, 36% of copper and 35% of zinc were extracted. After 12 days of bioleaching with a microbial consortium containing Leptospirillum spp., Sulfobacillus spp., Ferroplasma spp., and Acidithiobacillus spp. at 35 °C, the total recovery of metals from pyritic tailings reached 68% for copper and 77% for zinc; and subsequent cyanidation allowed 92% recovery of gold. Ferric leaching of two types of slag at 70 °C with the leachate obtained during bioleaching of the tailings and containing 15 g/L of Fe3+ allowed 88.9 and 43.4% recovery of copper and zinc, respectively, from copper slag within 150 min. Meanwhile, 91.5% of copper, 84.1% of nickel, and 70.2% of cobalt were extracted from copper–nickel slag within 120 min under the same conditions.

Processing of Alluvial Deposit Sands with a High Content of Copper and Nickel Using Combined Enrichment Technology

“…The authors [39] proposed the sequential biological leaching of pyrite wastes, as well as the leaching of non-ferrous iron-containing slags, as a promising method for mining waste processing. After the acid leaching stage, followed by 12 days of bioleaching, the total recovery of metals from pyrite tailings into the liquid phase was 68% for copper, 77% for zinc, and 75% for iron; recovery of gold by the cyanidation method has reached 92%.…”

Metal Recycling via Biohydrometallurgy

“…So führte die Biolaugung von Tailings mit acidophilen Mikroorganismen zu einem erhöhten Ausbringen von Fe, Cu, Co, Zn, Ni und Au bei der anschließenden Chloridlaugung der Biolaugungsrückstände 35. Ein weiteres Beispiel für einen integrierten Ansatz ist die Biolaugung von pyrithaltigen Flotationstailings mit acidophilen, Eisen‐ und Schwefel‐oxidierenden Mikroorganismen und dem anschließenden Einsatz der biogenen, Eisen‐reichen Laugungslösung zur Laugung von Wertmetallen aus Kupfer‐ und Nickel‐haltigen Schlacken 110.…”

An Autochthonous Acidithiobacillus ferrooxidans Metapopulation Exploited for Two-Step Pyrite Biooxidation Improves Au/Ag Particle Release from Mining Waste

“…In other words, the use of BioFe 3+ seems to be more effective at both 30 and 90 • C than the use of commercial salt. For example, the concentration of total Fe in the solution was up to 50% after preoxidation with the Fe 3+ salt, but up to 58.5% with BioFe 3+ ; the use of Fe 3+ salt also generated more sulfate precipitates [56] than the use of BioFe 3+ (Figure 4), according to the following reaction [14]:…”

“…The two-stage chemical-bacterial oxidation of metal sulfides has been used as an alternative pretreatment for efficient recovery of Au, since chemical preoxidation may provide short-term preprocessing of the energetic substratum for its subsequent bio-oxidation in the second stage of the process [13][14][15][16][17][18]. Because temperature influences the catalyzation of the sulfide oxidation [19], sulfidic elements are removed from the mineral concentrate Equation (1) if the initial chemical stage occurs at >70 • C. The second stage of biooxidation over the solid remnant enables Fe 3+ regeneration Equation ( 2) and bio-oxidation of reduced sulfur compounds such as S 0 Equation (3), increasing Au recovery from the FeS 2 concentrate.…”