Study of Hydrothermal Alteration and Mineralization in the Lahbako Field, Jember Regency, East Java Province

Administratively, the research location is in Lahbako Field, Jember Regency, East Java Province. This study discusses the geological characteristics, hydrothermal alteration, and mineralization in the study area. The method used is field data collection by mapping and laboratory analysis in the form of petrographic analysis and mineragraphic analysis. The research area is divided into three geomorphology units, namely a unit with steep hills, a unit with undulating hills, and a unit with sloping plains. The stratigraphy of the study area is divided into five-rock units, while the order of rock units from oldest to youngest is the volcanic Breccia unit, the intercalated Sandstone, and Claystone unit with Tuff insertion, the Diorite Intrusion Unit, the Granodiorite Intrusion Unit, and the youngest unit, namely Alluvium Unit. The research area has a high straightness density value and a straight lineage pattern that tends to be dense. The area with high lineament density is assumed to be the area with the best prospect of alteration and mineralization because the lineament reflects the geological structure which is the path of hydrothermal fluid passage that causes alteration and mineralization. Based on petrographic analysis, the research area has undergone alteration with the type of Philic alteration (Chlorite-Quartz-Feldspar), Prophiliic Alteration (Chlorite-Quartz-Feldspar) Feldspar-Quartz-Epidote) and Argillic Alteration (Alunite-Quartz-Biotite). The study area is indicated as an area with high sulfide epithermal mineral deposits where the indication is based on the discovery of vein textures in the form of Vuggy Quartz and ore minerals in the form of Silver, Copper, and Iron in mineragraphic analysis.

An Alternative Method for the Obtention of Ceramic Foams from Gold and Silver Tailings with High Pyrite Content

Mining extraction operations generate a large number of tailings that contain different mineral phases such as quartz (principally), complex silicates, metallic elements, etc. Tailings impose a serious concern as it is possible to have acid mine drainage potential, leaching, and percolation events of heavy metals into the environment under certain conditions. The objective of this work was to evaluate the technical feasibility of producing ceramic foams from gold and silver tailings with high sulfide gangue through a previous flotation process to eliminate impurities associated to this gangue, as it can produce SO2 in the foaming process, and to analyze the effect of the sintering time and the temperature on the characteristics of foams obtained with this type of waste. The results showed that the inverse flotation reduced the presence of impurities associated to sulfides. In addition, it was possible to observe that in the absence of a foaming agent, it was possible to obtain ceramic foams with an apparent density and a mechanical strength near to 1.0 g/cm3 and 0.5 MPa, respectively, when a higher sintering temperature and time were used. On the other hand, the presence of the foaming agent reduced the apparent density to 0.5 g/cm3 without decreasing to a great extent the mechanical strength of ceramic foams at lower sintering temperatures.

“Candidatus Thiovulum sp. strain imperiosus”: The largest free-living epsilon proteobacteraeota Thiovulum strain lives in marine mangrove environment.

A large (47.75±3.56 µm in diameter) Thiovulum bacterial strain forming white veils is described from marine mangrove ecosystem. High sulfide concentrations (up to 8 mM of H2S) were measured on the sunken organic matters (wood/bone debris) in laboratory conditions. This sulfur-oxidizing bacterium colonized such organic matter forming white veil. According to conventional scanning electron microscope (SEM) observations, bacterial cells are ovoid and slightly motile by numerous small flagella present through the cell surface. Intracytoplasmic large internal sulfur granules were shown suggesting a sulphidic-based metabolism. Observations were confirmed by sulfur elemental sulfur distribution detected by energy-dispersive X-ray spectroscopy (EDXS) analysis using environmental scanning electron microscope (ESEM) on non-dehydrated samples. Phylogenetic analysis of partial sequence of 16S rDNA obtained from purified fractions of this -proteobacteraeota strain indicates that this bacterium belongs to the Thiovulaceae cluster and could be one of the largest Thiovulum ever described. We propose to name this species “Candidatus Thiovulum sp. strain imperiosus”.

Strategy for Rapid Recovery of Simultaneous Sulfide and Nitrite Removal under High Substrate Inhibition

The paper deals with the strategy for a quick recovery of reactor treating sulfide and nitrite simultaneously under inhibition caused by high substrate concentration. For influent sulfide concentration of 360 mg S/L, respective sulfide and nitrite removal percentages dropped to 74.19% and 14.33% due to inhibition caused by high sulfide and nitrite concentrations. It was found that reduction in the influent substrate concentration (300 mg S/L) could not revive the nitrite removal performance in 4 days’ operation, which still showed a declining tendency from 47.16–18.52%. Regulating the influent pH around 6.70 ± 0.10, it only took 4 days to recover the performance for 300 mg S/L. Furthermore, at influent sulfide concentration increased to 360 mg S/L, respective sulfide and nitrite removal percentages were 99.76 ± 0.27% and 100%. The strategy of regulating influent pH could recover the process performance in a short term, which would provide great convenience for subsequent process research.

TREATMENT OF TRADITIONAL ETHANOL FERMENTATION WASTE WITH ELECTROLYSIS METHOD FOR DECREASING COD AND SULFIDE

Ethanol is produced from molasses by a fermentation process. In Bekonang, ethanol manufacturingby a home-scale industry so the waste just thrown away in free water then pollution occurs both in rivers and in paddy fields. Ethanol waste has very high chemical oxygen demand (COD) and contain high sulfide. Electrolysis that use for reduce leves COD dan Sulfide with electricity as main source for direct current flowing electricity (dc) to the anode and cathode. Electrolysis time 10, 15, 20, 25 and 30 minutes and voltage variation 5, 10 and 15 volt. Based on data obtained in the test COD obtained optimum levels of 284.5 mg/L from the initial content of 586 mg/L , at a time variation of 30 minutes and voltage 15 volt. The sulfide test obtained optimum levels of 0.0661 mg/L from the initial content of 0.305 mg/L, at time variation of 25 minutes and a voltage of 15 volt.

Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer.

THE RESULTS OF THE FUNCTIONAL STATE OF THE MEIOBENTHIC FAUNA RESEARCH IN HIGH-SULFIDE BIOTOPES OF COASTAL LAKES-LAGOONS OF THE KANDALAKSHA BAY (WHITE SEA)

The article presents the results of the studies of physiological state of meiofauna taken from the bottom sediments of two meromictic lakes which had different stages of geological isolation from the White Sea. It was concluded that active living benthic organisms of these high-sulfide biotopes could penetrate no deeper than the upper boundary of the hemocline. Organisms living at the depth of the upper redox-chemocline boundary (nematodes, chironomids and oligochaetes) in the lakes-lagoons of the Kandalaksha Bay (White sea) have high locomotor activity characteristics. Nematodes and rotifers were found on the lower edge of the chemocline, but they were motionless and did not show signs of active life. Therefore, they, with a high degree of probability, could be attributed to the dead component of the community. No meiobenthos was found in the anoxic zone at the bottom of the sulfide lake at a depth of 7.5 m. Finding abundant motionless benthic ciliates, belonging to the family Tintinnidae at the upper edge of the chemocline of Lake Trekhtsvetnoe does not allow researchers to make unambiguous conclusion about their physiological state. The main factor limiting the penetration of zoobenthic oxybionts into the redox zone of the studied meromictic White Sea lagoons is obviously the combined effect of deficiency of dissolved oxygen with simultaneous contamination of the aquatic environment and benthal with hydrogen sulfide. On the contrary, the positive properties of this habitat can be attributed to the high content of potential food resources (biomass of photo-and chemolithotrophic microorganisms), and, probably, the previously observed layer of the chemocline with an increased temperature. It is noteworthy that the latter phenomenon, which is observed in most of the stratified lakes-lagoons of the polar region, is most developed in the winter period.

3D Spatial Distribution of Arsenic in an Abandoned Mining Area: A Combined Geophysical and Geochemical Approach

Abandoned mine wastes, containing high sulfide contents, are of particular concern because of the formation of acid mine drainage (AMD), becoming an active and harmful point source of potentially toxic elements (PTEs) to the environment. A detailed evaluation of the chemical and mineralogical composition of mining wastes is necessary to determine effective remediation actions. Due to the high amount of generated wastes as a result of mining and processing activities, the cost and time consumed for this characterization are limiting. Hence, efficient tools could be applied to predict the composition of these wastes and their spatial distribution. This study aims to determine the physico-chemical characterization of wastes from mining activities using geochemical and geophysical techniques. The obtained results, both geochemical and geophysical, allow us to locate areas with a high potential risk of contamination by As in an economic and simple way, and enable us to design detailed geochemical sampling campaigns. In addition, the fact that there are conductive fractures in depth suggests the possible circulation of contaminants through them as well as the preferential lines of circulation.

Chemical Treatment of Highly Toxic Acid Mine Drainage at A Gold Mining Site in Southwestern Siberia, Russia

The critical environmental situation in the region of southwestern Siberia (Komsomolsk settlement, Kemerovo region) is the result of the intentional displacement of mine tailings with high sulfide concentrations. During storage, ponds of acidic water with incredibly high arsenic (up to 4 g/L) and metals formed on the tailings. The application of chemical methods to treat these extremely toxic waters is implemented: milk of lime Ca(OH)2, sodium sulfide Na2S, and sodium hydroxide NaOH. Field experiments were carried out by sequential adding pre-weighed reagents to the solutions with control of the physicochemical parameters and element concentrations for each solution/reagent ratio. In the experiment with Ca(OH)2, the pH increased to neutral values most slowly, which is contrary to the results from the experiment with NaOH. When neutralizing solutions with NaOH, arsenic-containing phases are formed most actively, arsenate chalcophyllite Cu18Al2(AsO4)4(SO4)3(OH)24·36H2O, a hydrated iron arsenate scorodite, kaatialaite FeAs3O9·8H2O and Mg(H2AsO4)2. A common specificity of the neutralization processes is the rapid precipitation of Fe hydroxides and gypsum, then the reverse release of pollutants under alkaline conditions. The chemistry of the processes is described using thermodynamic modeling. The main species of arsenic in the solutions are iron-arsenate complexes; at the end of the experiments with Ca(OH)2, Na2S, and NaOH, the main species of arsenic is CaAsO4−, the most toxic acid H3AsO3 and AsO43−, respectively. It is recommended that full-scale experiments should use NaOH in the first stages and then Ca(OH)2 for the subsequent neutralization.