The use of microorganisms notably bacteria in mineral processing industry is presently one of the leading emerging pre-treatment techniques being employed for the processing of double refractory gold ores and concentrates. Currently numerous studies are in progress to further improve upon the efficiency of the bacterial process and to investigate the potential of other microorganisms. In this study, microbial pre-treatment of double refractory gold ore (sample A) and concentrate (sample B) was investigated using a white-rot fungus, Tramestes versicolor (ATTC 20869). Pulp density, temperature, pH and retention times were the process variables considered. Preliminary studies investigated the amenability of selected pure sulfide sulfur minerals, various types of coal and ore sample A to fungal degradation. Various pre-treatment scenarios were also studied to optimize gold extraction. These were single stage, a two-step and two stage processes involving the well known chemolithotrophic bacteria Acidithiobacillus thiooxidans (ATTC 15494), Acidithiobacillus ferrooxidans (ATTC 19859) and Leptospirillum ferrooxidans (ATTC 53992), the bacterium, Streptomyces setonii (ATTC 39116) and the white-rot fungus, Tramestes versicolor. Preliminary results for sample A indicated that T. versicolor did not degrade sulfides significantly at its optimum growth conditions (pH range of 4.5 – 5.0) and carbonaceous matter was not degraded but rather passivated as preg-robbing decreased significantly. Lignite was inert to passivation by T. versicolor unlike bituminous coal and to lower extent anthracite. Stimulated alkaline conditions (pH range of 9.5 – 10.5) recorded the overall best sulfur oxidation. Results of both the single stage and two-step processes confirmed that carbonaceous matter was passivated by T. versicolor; as preg-robbing decreased significantly from 18.1% to ≤ 1.0%. Gold extraction by cyanidation of the pre-treated sample A was 82.5% for the two-step as against 80.5 % for the single stage and 15.0% for the untreated sample. Application of the two-step and single stage process conditions to sample B resulted in 93.3% and 89.9% gold extraction respectively as against untreated concentrate of 30.5%. For the various two stage pre-treatment processes investigated, the abiotic - S. setonii process recorded the best gold extraction of 81.5% for sample A. S. Setonii degraded carbonaceous matter unlike T. versicolor which passivated it. However, it takes only 3 - 7 days for T. versicolor to effect passivation and eliminate preg-robbing while 14 - 56 days is required for S. setonii to degrade carbonaceous matter significantly. The result of the novel microbial pre-treatment process indicated that sulfide sulfur was degraded under alkaline conditions and carbonaceous matter passivated by T. versicolor at its optimum growth conditions. This led to a significant improvement in gold extraction from the double refractory gold ore and concentrate investigated. / Thesis (Master, Mining Engineering) -- Queen's University, 2008-09-22 16:42:01.272

Hydrothermal fluid flow is spatially and genetically associated with deformation in the earth�s crust. In the Otago Schist, New Zealand, the circulation of hydrothermal fluids in the Cretaceous formed numerous mesothermal gold-quartz vein deposits. Otago schist rocks are largely L-S tectonites in which the penetrative fabric is the product of more than one deformation phase/transposition cycle. Regional correlation of deformation events allowed mineralised deposits to be related to the structural evolution of the Otago Schist. Compilation of a detailed tectonostratigraphy of New Zealand basement rocks reveals that extensional mineralisation correlates with the onset of localised terrestrial fanglomerate deposition, thermal perturbation and granitic intrusion that mark the beginning of New Zealand rifting from the Antarctic portion of Gondwana. Laminated and breccia textures in mineralised veins suggest that host structures have experienced repeated episodes of incremental slip and hydrothermal fluid flow. However, analysis of vein orientation data in terms of fault reactivation theory (Amontons Law) shows that most deposits contain veins that are unfavourably oriented for frictional reactivation. Repeated movement on unfavourably oriented structures may involve dynamic processes of strain refraction due to competency contrasts, the effect of anisotropy in the schist, or localised stress field rotation. Deposits have been classified on the basis of host structure kinematics at the time of mineralisation into low angle thrust faults, and high angle extensional fault - fracture arrays. Low angle deposits have a mapped internal geometry that is very different from conventional imbricate thrust systems. This study applied ⁴⁰Ar/�⁹Ar geochronology to selected deposits and has identified at least three distinct mineralisation events have occurred within the central axial belt during the Cretaceous. Relationships between radiometric apparent age and inferred crustal depth reveal that after metamorphism, the onset of cooling and rapid exhumation of the schist belt coincides temporally and spatially with the age of mineralisation and structural position of a regional scale low angle shear zone in Otago.

Bibliography: leaves 186-210. / v, 242 leaves, [19] leaves of plates : ill. (chiefly col.), map ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The Granites gold deposits of The Granites-Tanami Inlier are the principal interest of the thesis. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1998

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1900. / The entire thesis text is included in file. Typescript. Illustrated by authors. Degree awarded only to Isaac Peter Frazier. Title from title screen of thesis/dissertation PDF file (viewed )

Thesis (M.Sc.) - Carleton University, 2002. / Accompanying material: 2 maps in pocket. Includes bibliographical references (p. 119-127). Also available in electronic format on the Internet.

Thèse (D.R.Min.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Thèse (D.R.Min.)--Université du Québec à Chicoutimi, 1994. / Document électronique également accessible en format PDF. CaQCU

Thèse (D.R.M.)--Université du Québec à Chicoutimi, 2001. / Document électronique également accessible en format PDF. CaQCU

Thèse (D.R.Min.) -- Université du Québec à Chicoutimi, 2003. / Bibliogr.: f. 342-358. Document électronique également accessible en format PDF. CaQCU

Thèse (M.Sc.T.) -- Université du Québec à Chicoutimi, 2006. / Bibliogr.: f. 204-211. Document électronique également accessible en format PDF. CaQCU