PROMINE

The research sites are located in the village of Berambang, Sekotong District, West Lombok Regency,West Nusa Tenggara Province. This area was dominated by volcanic rocks composed of dasiticvolcanic rock, diatrema breccia, and diorite intrusion. Berambang area shows alteration in the form ofpotassic, propylitic, advanced argillic, and argillic alterations where in some places accompanied bypyritisation and stockwork structure, the type of mineralization in this area is a porphyry copper-goldtype. In the potasic alteration zone there are minerals that have a strong anomaly response to themagnetic due to the presence of oxide minerals magnetite (Fe2O3). Mineral sulfides such as pyrite(FeS2) and chalcopyrite (CuFeS2) will also provide significant anomalous responses that have anabundance of 2-5% in the potassic zone. In a propylitic alteration zone characterized by chlorite,calcite and epidote minerals that do not respond to magnetic anomalies, the presence of pyriteminerals, hematites and chalcopyrite with abundance of ≤1% will provide some magnetic anomaly inthe propylitic zone. As for advanceargillic alteration zones characterized by mineral andalusite, aluniteand quartz, there will not be any magnetic anomalies, the phenomena was due to the rarity ofmineralization in this zone gives an insignificant anomalous impact. Meanwhile, for the argillic zonecharacterized by mineral illite, kaolinite and smectite will not have anomalous magnetic impact, veryrare mineralization in the argillic zone so that the magnetic anomaly is not significant. From the floatingEuler 3D shows an anomalous source from a depth of 0 meters to a depth of more than 400 meters.

Solution pH and Jarosite Management during Ferrous Iron Biooxidation in a Novel Packed-Column Bioreactor

Jarosite formation is undesirable in bioleaching processes as it depletes the needed ferric reagent for the oxidation of most sulfide minerals. Although it creates kinetic barriers thereby retarding the leach rates of most minerals, jarosite serves as support for the attachment of bioleaching microbes, facilitating biooxidation rate. Microbial ferrous-oxidation by mesophilic microbe was studied in a recently reported novel packed-column bioreactor with a view to investigate the potential of using solution pH to manage jarosite accumulation in the bioreactor in addition to establishing a base case data for the bioreactor. Experiments were conducted in the bioreactor packed with glass balls (15mm diameter) at constant temperature of 38.6 °C, residence time of 18 hours, airflow rate of 20 mLs-1and pH values of 1.3, 1.5 and 1.7. The results showed that the amount of jarosite accumulation is proportional to the solution pH, and to the duration of operation of the bioreactor. Jarosite precipitation concentrations of 4.95, 5.89 and 7.08 gL-1were obtained after 10 days of continuous operation at solution pH values of 1.3, 1.5 and 1.7 respectively, while after 15 days the precipitations concentrations increased to 5.50, 7.90, 9.98 gL-1respectively. The results also showed that 33% and 52% precipitate reduction could be achieved by gradual decrease in the bioreactor solution pH to 1.5 and 1.3 after being continuously operated for 10 days at pH 1.7 respectively after an addition of 5 days. A maximum ferrous oxidation rate (), 6.85 mmol.L-1.h-1and the affinity kinetic constants (,), of 0.001 and 0.006 for Hansford and Monod models respectively. Although a directly relationship exist between jarosite formation and pH, the results of this study may be relevant in bioleach heaps or at least in column bioreactors to manage/control jarosite accumulation thereby improving the leach kinetics of mineral sulfides.

Initial Attachment and Biofilm Formation of a Novel Crenarchaeote on Mineral Sulfides

This study focused on colonization and biofilm formation of a new crenarchaeoteAcidianussp. DSM 29099 on pyrite and chalcopyrite. Confocal laser scanning microscopy (CLSM) in combination with several fluorescent stains was applied to examine spatial distribution of cells and biofilms, as well as extracellular polymeric substances (EPS) production on the substrates. Around 60% and 35% of the inoculum adhered to pyrite and chalcopyrite within 2 h, respectively. Cells ofAcidianussp. DSM 29099 were heterogeneously distributed on both pyrite and chalcopyrite surfaces, while large mineral surfaces remained uncolonized. Biofilm cells on pyrite were often found to be embeded in EPS. EPS residues like mannose and glucose were possibly involved in intial attachment to pyrite. A mature biofilm on pyrite was developed after 2-4 days of incubation.

Saline Water Bioleaching with Thermophilic Fe(II) Oxidising Microorganisms

The chloride tolerance of three Fe (II)- and sulfur-oxidising thermophiles and the effect of chloride on metals extraction from mineral sulfides were studied. Initially, 10-day bioleaching tests (60 °C) were conducted using pyrite (FeS2), chalcopyrite (CuFeS2) or pentlandite ((Ni,Fe)9S8) concentrates as substrate in basal salts medium (BSM), and the activities of Sulfolobus (S.) metallicus, Acidianus (A.) brierleyi and Metallosphaera (M.) hakonensis were compared. Fe (II) oxidation, as indicated by an increase in oxidation reduction potential (ORP), was observed in all combinations except A. brierleyi growing on chalcopyrite. The presence of added NaCl resulted in lower ORP after 10 days of bioleaching in all cases. In ancillary tests using BSM-Fe (II) growth medium with added NaCl it was found that cell counts at the end of Fe (II) biooxidation provided the most reliable estimate of tolerance to NaCl. On this basis, the rank order of salt tolerance is S. metallicus >>>A. brierleyi > M. hakonensis.

Chalcopyrite and Bornite Differentially Affect Protein Synthesis in Planktonic Cells of Acidithiobacillus ferrooxidans

Acidithiobacillus ferrooxidans is used in bioleaching industrial operations to recover metal ions from mineral sulfides. Chalcopyrite and bornite are copper sulfides that have the same elemental composition, but differ in their susceptibility to the bioleaching process. Our objective was to identify differentially expressed proteins in A. ferrooxidans LR cells exposed to chalcopyrite or bornite, as a sole energy source, for 24 hours. Compared to the control (without minerals), proteins were induced or repressed in planktonic cells after contact with chalcopyrite or bornite by 24 hours. These results demonstrated that the time of exposure to the copper minerals was enough to trigger distinct responses in the A. ferrooxidans metabolism.

Combined Atomic Force and Fluorescence Microscopy of Biofilms formed by Leaching Bacteria on Opaque Substrata

Leaching bacteria attach to their substrates, i.e. mineral sulfides, and form monolayered biofilms. In this study the biofilm formation of Acidithiobacillus ferrooxidans A2 on pyrite was examined using atomic force and epifluorescence microscopy (AFM and EFM, respectively). A novel system by JPK instruments, the BioMaterial WorkstationTM, allows the investigation of the same location on an opaque sample with AFM and EFM. Until recently this was only possible for translucent samples. Sessile bacteria on pyrite coupons were stained with 4’,6-diamidino-2- phenylindol (DAPI) and visualized by EFM as well as AFM. The best imaging conditions for AFM were assessed. Scans of bacteria attached to pyrite were performed in contact mode in air as well as in tapping mode in fluid. Imaging in fluid was more challenging than imaging in air as bacteria tend to detach from their substratum. To avoid the dislocation of microorganisms by the AFM probe the sample was dried in air for 1 h prior to scanning in fluid. Scanning in air was performed with the whole range of cantilever spring constants tested (k = 0.03 N/m to k = 0.65 N/m) while, for scanning in fluid, best results were achieved using stiffer cantilevers (k = 0.65 N/m).