Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature

Abstract

Biohydrometallurgy is believed to be a promising future study field for the recovery of lead (Pb) from ores/concentrates since the pyrometallurgical/hydrometallurgical processes have been largely applied to recover Pb to date, which operates at high temperature and generates volatile Pb matters that are hazardous and carcinogenic to human health. Hence, the main purpose of this study was to investigate the biohydrometallurgical extraction of Pb from the Indonesian galena concentrate through bioleaching using an iron- and sulfur-oxidizing mixotrophic bacterium (identified as Citrobacter sp.). The bioleaching experiments were conducted in shake flasks containing the modified LB broth medium supplemented with galena concentrate with a particle size of d 80 = 75 μm at room temperature. Both semi-direct and direct bioleaching methods were employed in this study. The bacterium was able to extract lead (Pb) from galena concentrate with high selectivity to Cu and Zn (0.99 and 0.86, respectively). The highest extraction level of 90 g lead dissolved/kg galena concentrate was achieved using direct bioleaching method at bioleaching conditions of 2% w/v pulp density, 5 g/L FeCl 3 , 50 g/L NaCl, 20 g/L molasses and a rotation speed of 180 rpm at room temperature (25°C). The addition of FeCl 3 , NaCl, and molasses increased the lead leaching efficiencies, which were also evidenced by the FTIR, XRD, and SEM-EDS analyses. From industrial and commercial standpoints, the selective bioleaching represented in this study may be beneficial to the development of lead leaching from sulfide minerals, since insoluble anglesite (PbSO 4 ) precipitates are formed during ferric sulfate oxidation, thus making the recovery of lead through bioleaching unpractical.

Mixotrophic bacteria for environmental detoxification of contaminated waste and wastewater

“…Mixotrophic Citrobacter sp. capable of oxidizing both iron and sulfur, as well as proliferating at high NaCl concentration, is highly resistant to toxic metals and can selectively leach Pb instead of Cu and Zn from galena concentrate at room temperature (25 °C) and a pH range of 3.5 -4.6 (Chaerun et al, 2020). This process provides a more sustainable energy efficient process avoiding the use of costly anti-corrosive materials of conventional lead leaching processes.…”

A Comparative Study on Bioleaching Properties of Various Sulfide Minerals Using Acidiphilium cryptum

“…In a biological leaching study on lead zinc mine tailings consisting of complex minerals such as sphalerite, pyrite, calcite, and quartz, Zn leaching rates were 2.74 times (10% pulp density) and 9.25 times (20% pulp density) higher than the Fe leaching rate [34]. Meanwhile, some precipitates, such as anglesite, may be formed during the bioleaching process [35,36], but they were not considered in this study.…”

Study of Galena Ore Powder Sintering and Its Microstructure

“…Generally, increasing the compaction pressure within the allowed limit, using a wide range of particle-size powder, and adding lubricant materials leads to an increase in GD and subsequently increases the SD of the final product unless otherwise required. The as-received galena density was determined using the water displacement method and found to be approximately 7.41 g/cm 3 , to be a reference for GD and SD of galena powder products. Therefore, approaching this value is evidence of the success of sintering in terms of compaction pressure, sintering temperature and atmosphere, and time.…”

“…The formation of galena is often linked to the hydrothermal alteration of leadbearing minerals in the presence of sulfur-rich fluids. Additional compounds like lead carbonate and lead sulfate can also be present in galena, depending on the location of the ore mining site [1][2][3][4][5][6]. PbS, with a lead-to-sulfur ratio of 86:13 mass percent, is found in the Japanese and American galena ores [1].…”