Ces travaux s’intéressent au comportement de pâtes de ciment de différentes natures cimentaires exposées à une eau douce naturelle et plus particulièrement aux interactions avec les éléments biologiques. Cette étude est basée sur l’analyse comparative d’échantillons placés en milieu naturel (Moselle) et en milieux artificiels de laboratoire. Quels que soient les milieux et les microorganismes considérés, les résultats montrent une modification de la minéralogie de la surface et du réseau poreux des échantillons (taux de porosité, propriétés de transferts). Les essais en laboratoire ont permis d’isoler l’influence spécifique des bactéries dans les phénomènes de biolixiviation. Le dénombrement bactérien montre aussi que la densité de cellules présentes dans le biofilm recouvrant les échantillons dépend peu de la nuance cimentaire, excepté pour les ciments au calcaire. Les observations au MEB ont révélé, sur l’ensemble des échantillons, la présence abondante de diatomées en partie recouvertes par une couche minérale issue d’une cristallisation secondaire. La colonisation de la surface par ces diatomées est influencée par la géométrie et la nature minéralogique des échantillons. Les résultats d’essais en laboratoire ont montré qu’elles ont des interactions avec la pâte de ciment, l’évolution des densités de population de diatomées coïncide en effet avec l’évolution des caractéristiques de porosité (taux de porosité, propriétés de transferts) / This work focuses on the behavior of cement pastes of different cement bases exposed to natural fresh water and on the interactions with the biological elements. This study is based on the comparative analysis of samples immersed in natural environment (Moselle) and in artificial laboratory media. Whatever the media and microorganisms considered, the results show a change in the mineralogy of the surface and the porous network of the samples (porosity rate, transfer properties). Laboratory tests highlighted the specific influence of bacteria in bioleaching phenomena. The bacterial count also shows that the density of cells present in the biofilm covering the samples does not mainly depend on the cementitious grade, except for the limestone cements. The SEM observations revealed the abundant presence of diatoms on all samples. Diatoms are partly covered by a mineral layer resulting from secondary crystallization. The colonization of the surface by these diatoms is influenced by the geometry and mineralogical nature of the samples. The results of laboratory tests have shown that they interact with cement paste; the evolution of diatom population densities coincides with changes in porosity characteristics (porosity rate, transfer properties)

Acidophilic bacteria are able to tolerate acidic environment and also contribute to the lowering of environmental pH value, implying potential applications in metal-leaching technology extracting metals from tailings and electronic wastes. In this study, we conducted a sampling campaign in abandoned Tin mine in Ha Thuong, Thai Nguyen province, to isolate acidophilic bacteria and to study physiological characteristics of the isolated bacteria. As a result, two acidophilic bacteria were successfully isolated and identification by 16S rDNA gene sequences showed that the two bacteria are similar to Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (98% and 94 % of similarity, respectively). Both strains are tolerant of pH in the range of 3 and have the ability to grow optimally at temperatures of 30°C. / Vi khuẩn ưa axit có ý nghĩa ứng dụng trong công nghệ tách rút kim loại từ quặng đuôi và ngay cả từ rác thải linh kiện điện tử. Trong nghiên cứu này, chúng tôi đã tiến hành thu mẫu ở mỏ thiếc bỏ hoang ở Hà Thượng, Thái Nguyên nhằm phân lập được nhóm vi khuẩn ưa axit và qua đó nghiên cứu một số đặc điểm sinh lý của vi khuẩn này. Kết quả chúng tôi đã phân lập được hai chủng vi khuẩn ưa axit. Định dạng bằng nhận diện trình tự gen 16S rADN cho thấy hai vi khuẩn này có độ tương đồng là 98% với vi khuẩn Acidithiobacillus ferrooxidans và 94% Acidithiobacillus thiooxidans. Cả hai chủng vi khuẩn đều có tính chịu pH trong khoảng 3 và có khả năng sinh trưởng tối ưu ở nhiệt độ 30oC.

Acid mine drainage (AMD) is a worldwide environmental problem associated with the mining wastes, generated from active and inactive mining sites from mineral processing activities. AMD is defined as the drainage that occurs as a result of oxidation of sulphide minerals/wastes/tailings when exposed to air and water in the presence of chemolithotrophs namely the Acidithiobacillus sp. AMD is characterised by low pH and increased acidity due to elevated heavy metals and sulphate concentration. The acid production potential was carried out for sulphide minerals such as pyrite and chalcopyrite and copper tailings sample in the absence and presence of bacteria namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Acidity was generated in all the cases due to the oxidation of the mineral samples. The oxidation was found to occur at a higher rate in the presence of the bacteria compared to the control samples. Bioremediation experiments were conducted on acid mine water collected from the Ingaldahl Mines, Chitradurga, Karnataka, India, using organic and inorganic substrates. In the experiments with rice husk, complete removal of metal ions from the acid mine water was achieved with an attendant increase in the pH of the acid mine water from 2.3 to 5.5. About 21% of sulphate could be removed using Dsm. nigrificans from acid mine water pretreated with rice husk at pH 5.5 and this was further increased to 40% by the supplementation of organic components. The rice husk filtrate was found to serve as a good growth medium for Dsm. nigrificans. About 96 % of Fe, 75 % of Zn, 92 % of Cu and 41 % of sulphate removal was achieved from the acid mine water of pH 2.4 with a concomitant increase in the pH value by two units after interaction with the tree bark. About 56 % and 71 % of sulphate reduction could be achieved at initial pH values of 4.1 and 5.5 respectively of the acid mine water pretreated with E. tereticornis (Sm) bark, after inoculation with Dsm. nigrificans. The complete removal of Fe2+ and Fe3+, 80% of Zn, 83% of Cu and 62% of sulphate could be removed from acid mine water using fly ash as the substrate with an increase in pH of acid mine water from 2.3 to 7. About 68% of sulphate reduction at pH 6.8 could be achieved in acid mine water pretreated with fly ash in the presence of Dsm. nigrificans. With red mud as the substrate, complete removal of all the metal ions namely Fe2+, Fe3+, Zn, and Cu from acid mine water was achieved with a concomitant increase in the pH from 2.3 to 8. The sulphate reduction was increased to about 51% at pH 7.2 when the acid mine water pretreated with red mud was inoculated with Dsm. nigrificans. The adsorption experiments carried out on the acid mine water using either organic or inorganic substrates indicated that the free energy of adsorption was negative for all the chosen metal ions attesting to favorable interaction. The adsorption isotherms of the metal ions for rice husk exhibited Langmuirian behaviour, while those for the other substrates adhered to both Langmuir and Freundlich relationships. The adsorption process was found to be endothermic in nature for rice husk, fly ash and red mud. On the contrary, the adsorption onto tree bark showed exothermic behaviour. The adsorption kinetics of the metal ions onto the various substrates adhered to the first order Lagergren equation. The metal uptake processes by the organic and inorganic substrates chosen for this study involve ionic, chemical and physical forces of adsorption. The different types of functional groups present on the surface of the substrates such as carboxyl, hydroxyl and carbonyl, as revealed by FTIR spectroscopic studies, partake in metal binding. The metal ions will also be adsorbed by complexing with the negatively charged reaction sites on the substrate surfaces. Furthermore, the complex solution chemistry of the metals as a function of pH has also to be taken into consideration. The mechanism of sulphate reduction by Dsm. nigrificans in the presence of organic carbon can be illustrated as: 2CH2O + SO42- + 2H+  2CO2 + 2H2O + H2S M2 + H2S  MS  + 2H+ where, CH2O represents the organic matter and M represents the metal ion.

The aim of the EU BIOMOre Project is to investigate the potential to extract copper from Sandstone formations in the North-Sudetic Trough which lies along the border between Poland and Germany. A new mining concept called bioleaching shall be applied in thin and very low permeable copper mineralization zones (order of 0.2 mD). Briefly, bioleaching process is the injection of a lixiviant (sulphur acid containing ferric iron) and then extraction of a pregnant leach solution through boreholes at the ground surface. This concept requires another special technique which is called hydraulic stimulation. Cracks along a wellbore are generated by pumping large quantity of fluid under high pressure into a cased section of rock during a hydraulic stimulation. This work at hand focuses on the geotechnical methods and scientific-engineering approaches used for extracting copper from very thin mineralization zones. The geological setting with faults and in situ stress state of the exploration zone is generated using measurements, visualised by 3D CAD model (RHINO), and computed via the Discrete Element code 3DEC. The preliminary drilling (stacked dual lateral wellbore) and stimulation design (plug-and-perf completion) are selected based on comprehensive literature survey and industry-based consultancy. In order to calibrate the calculated stress state in 3D, candidate sites for the hypothetical drilling-stimulation are detected using 2D GIS map (QGIS) at CAD model (RHINO). Trend of calculated stresses is in good agreement with the measured ones (σH > σv > σh). The final decision of selecting a drilling-stimulation site is made by using both GIS map and 3D CAD model. A hypothetical drilling-stimulation can be performed up to the depth of 1564 m in the Rotliegend & Grauliegend Sandstone with shale, which is overlain by (Zechstein) Limestone. During a possible stimulation, limestone’s integrity as a caprock and as a stress barrier is of great importance in addition to connect two lateral wellbores for facilitating flow of lixiviant. The preliminary geometrical design of stimulation is set with the cluster spacing (distance between fractures) of 20 m. Subsequent to final cost estimation of selected preliminary drilling-stimulation design, it is decided to use pinpoint (1,200,000 Euro) instead of plug-and-perf completion (2,345,300 Euro) since it is more economical. A possible drilling operation is anticipated to cost approximately 9,000,000 Euro. The 3D in situ stress model is calibrated before transferring of stress state into the sub-model which is used to optimise the selected stimulation design. The results of the last (DEM) sub-model are employed to reduce costs, to enhance the connection between branches of wellbores for bioleaching and to hinder possible penetration of fractures into the caprock. The preliminary geometrical design of stimulation is then modified based on these calculation results while increasing the cluster spacing from 20 m to 40 m. This is performed due to high stress-shadows (alteration of the stresses between fractures in a stimulation) encountered at the preliminary calculations. Results showed that, after the 80 seconds injection duration of water with 0.16 m3/sec into the sandstone, two wellbore laterals are expected to be connected by three generated cracks. They exhibit average aperture and transmissivity of 4.1 mm and 5.8 . 10-8 m2/sec, respectively. Furthermore, fracture initiation pressure ranges between 30 – 35 MPa at the drilling depth. The conclusions can be drawn that through the assessment of 3D CAD, GIS, and numerical DEM modelling methods, approximately 49% of cost reduction can be achieved by employing pinpoint instead of plug-and-perf completion. That is an important proof of the systematically approach for a stimulation planning wherein all necessary phases such as in situ stress estimation, modelling and cost assessment should have been considered. This work can be considered as a milestone for studies of stimulation designs which has been newly initiated in the EU-Region as a promising method for efficiency considering unconventional ore extraction. Moreover, this dissertation revealed again the emerging importance of integrated geotechnical information systems analogous to BIM (Building Information Systems).:LIST OF FIGURES LIST OF TABLES NOMENCLATURE ABSTRACT ZUSAMMENFASSUNG ACKNOWLEDGEMENTS 1. OUTLINE AND OBJECTIVE OF THE DISSERTATION 2. STATE OF THE ART 2.1. INTRODUCTION TO STIMULATION TECHNOLOGIES, EQUIPMENT AND DESIGNS 2.1.1. Technical instruments and frac-materials 2.1.2. Wellbore completion designs 2.1.3. Location and orientation of a wellbore 2.1.4. Fracture placement designs 2.1.5. Summary and conclusions 2.2. MEASUREMENT AND MODELLING OF UNDERGROUND STRESS FIELD 3. DETERMINATION AND MODELLING OF IN SITU STRESS FIELD IN THE NORTH SUDETIC TROUGH 3.1. GEOLOGICAL SETTING OF THE MODELLED REGION 3.2. SIMULATION OF THE IN SITU STRESS FIELD 3.2.1. Determination of the stress regime by measurements 3.2.2. Stepwise procedure of the stress field modelling 3D CAD assisted structural model of geological setting 3D DEM model for stress field simulations 2D GIS maps used for detection of drilling-stimulation sites 4. DRILLING AND WELLBORE DESIGN CALCULATIONS WITH COST ESTIMATION 4.1. DESIGN CALCULATIONS AND TECHNICAL REQUIREMENTS OF DRILLING AND WELLBORE 4.2. ECONOMICAL EVALUATION OF THE SELECTED DRILLING AND WELLBORE DESIGN 5. MODELLING OF THE HYDRAULIC STIMULATION AT THE SELECTED DRILLING SITE IN SANDSTONE 5.1. FINAL CALIBRATION OF THE 3D STRESS FIELD MODELS 5.2. DISCRETE ELEMENT MODELLING OF THE STIMULATION DESIGN AT THE SELECTED DRILLING SITE 5.3. DESIGN OPTIMIZATION STUDY OF THE STIMULATION MODEL AND FINAL COST ESTIMATION 6. SUMMARY AND CONCLUSIONS REFERENCES APPENDIX-A APPENDIX-B APPENDIX-C