Description:
Victoria has yielded 2500 tonnes or almost 2 per cent of the world’s gold, mostly mined between 1851 and 1910. Some 55 per cent was placer gold from modern and palaeostream systems, and from eluvial deposits. The rest came from primary quartz vein-related deposits........
Description:
Victoria has yielded 2500 tonnes or almost 2 per cent of the world’s gold, mostly mined between 1851 and 1910. Some 55 per cent was placer gold from modern and palaeostream systems, and from eluvial deposits. The rest came from primary quartz vein-related deposits........
Description:
Sampling protocols that are designed to suit the mineralisation style will result in a reduction of the nugget effect and hence resource risk. The a priori need for all sampling programs is the effective characterisation of the mineralisation type(s) to support optimisation. This requires a program of sampling for sampling followed by holistic characterisation. At each end of the coarse-gold to fine-gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated gold particles, through to extremely difficult for coarse nuggety mineralisation. Many deposits contain a proportion of both particle size types. The proportion and size of coarse gold particles has a direct impact on the effectiveness of sampling, where coarser particles will require larger samples and more specialised protocols. The nature of mineralisation geology/mineralogy and associated gold particle sizing can only be determined by sampling to facilitate optimised protocols. Mineralogical studies, focusing on particle size, particle clustering and distribution in host minerals, are required as part of wider paragenetic and metallurgical investigations. This paper discusses the role of mineralogical studies in the characterisation of gold ores for sampling optimisation through a series of case studies.
Description:
The attrition of activated carbon, and the loss of gold associated with it, is of significant economic importance to the operation of a CIP/CIL circuit. The focus of this study was on activated carbon recovered from an elution circuit which was deemed too fine for reuse. Results of cyclosizer and laser particle size analysis identified that most of the carbon was contained in the larger size fraction suggesting formation by abrasion. Digestion and AAS analysis of the individual size fractions identified a disproportionate concentration of gold in the finer size fractions which was identified by scanning electron microscopy to be due to the presence of fine metallic gold formed as a result of the acid washing process. Attempts to strip the remaining gold using sodium hydroxide or sodium sulphide based solutions proved unsuccessful due to poor elution efficiencies and re adsorption of gold. Upgrading of the material by froth flotation was also investigated using various conventional flotation reagents which had some success in concentrating the free metallic gold, however, grade and/or recoveries were considered less than desirable. Greater success was ultimately found in the transfer of gold from the fine carbon material onto coarser virgin activated carbon using a caustic cyanide solution. Sodium sulphide, sodium chloride and ammonium chloride based solutions were also trialled but proved less successful owing to their inability to mobilise metallic gold or gold cyanide species. Repetition of the transfer process proved capable of stripping 97% of the gold contained on the carbon fines for a bed volume ratio of 6:1.
Description:
The attrition of activated carbon, and the loss of gold associated with it, is of significant economic importance to the operation of a CIP/CIL circuit. The focus of this study was on activated carbon recovered from an elution circuit which was deemed too fine for reuse. Results of cyclosizer and laser particle size analysis identified that most of the carbon was contained in the larger size fraction suggesting formation by abrasion. Digestion and AAS analysis of the individual size fractions identified a disproportionate concentration of gold in the finer size fractions which was identified by scanning electron microscopy to be due to the presence of fine metallic gold formed as a result of the acid washing process. Attempts to strip the remaining gold using sodium hydroxide or sodium sulphide based solutions proved unsuccessful due to poor elution efficiencies and re adsorption of gold. Upgrading of the material by froth flotation was also investigated using various conventional flotation reagents which had some success in concentrating the free metallic gold, however, grade and/or recoveries were considered less than desirable. Greater success was ultimately found in the transfer of gold from the fine carbon material onto coarser virgin activated carbon using a caustic cyanide solution. Sodium sulphide, sodium chloride and ammonium chloride based solutions were also trialled but proved less successful owing to their inability to mobilise metallic gold or gold cyanide species. Repetition of the transfer process proved capable of stripping 97% of the gold contained on the carbon fines for a bed volume ratio of 6:1.
Description:
The University of Ballarat organizes international excursion for its undergraduate geology students to provide them an opportunity to learn and gain international experiences of geology. The university previously organized an excursion of New Zealand in November-December 2006 to provide students knowledge about plate boundary and gold mineralization. The excursion was sponsored by Oxiana Limited, the Bicentennial Gold 88 Endowment, Newmont Australia Limited, and Castlemaine Goldfields Ltd. The excursion was planned for 17 days and visit to the Taupo Volcanic Zone, Kaikoura, The Waipara, Mt Cook and the Tasman Glacier, Macraes gold mine, Otago's silcretes, Queenstowm, and Milford Sound. More information about 2006-excursion can be found on the website at http://www.ausimm.com.au/main/education/award-bice-gold-php.
Description:
Orogenic gold deposits in central Victoria and Reefton formed during the evolution of a Paleozoic accretionary system along the Pacific margin of Gondwana. The majority of deposits in both camps are characterised by coarse-grained gold that is hosted in laminated to massive quartz veins. These ‘lode’ structures are developed in isoclinally folded turbidites that have been metamorphosed to lower greenschist facies. At Fosterville, diffuse zones of mineralization occur along a high-angle reverse fault zone consisting of en-échelon, strike-parallel segments with oblique slip and strike slip movement. The Globe-Progress deposit is associated with an arcuate shear that flattens with depth forming a listric ramp flat. In contrast to ‘classic’ lode-style deposits, mineralization at Fosterville and Globe-Progress is predominantly hosted by massive sandstone beds, in quartz/carbonate vein stockworks, and in clay-rich fault breccias of quartz vein and sulfidic wall rock fragments. The porous sandstones, which are intercalated with carbonaceous slates, have a bleached appearance, are invariably sericitized and carbonatized, and are 'impregnated' with a disseminated arsenopyrite-pyrite(±stibnite) assemblage. Gold occurs as sub-micron inclusions within the sulfides and rarely as free grains with a diameter of 1-10 microns. Highest-grade disseminated mineralization occurs within acicular arsenopyrite crystals. Fluid inclusions from Fosterville range in composition from high salinity and relatively high CO2, to low salinity and H2O-predominance, suggesting precipitation of at least a portion of the veins under epizonal conditions.....
Description:
By studying backscatter electron (BSE) micrographs, and the major- and trace-element geochemistry of gold bearing arsenopyrite from the late-Archaian Bardoc Tectonic Zone, Western Australia, this study helps constrain the hydrothermal conditions of gold deposition associated with this common ore mineral.
Description:
The history of gold has traditionally excluded a whole quadrant from its landscape. This chapter aims to reconstruct the close association between Aboriginal people and Victoria's gold mining that undoubtedly existed during the nineteenth century. It is especially appropriate to do so in a book that reconsiders the Eureka story from unexpected angles in order to reflect generally upon the historical inheritance of the goldrushes upon Australian society.
Description:
The history of gold has traditionally excluded a whole quadrant from its landscape. This chapter aims to reconstruct the close association between Aboriginal people and Victoria's gold mining that undoubtedly existed during the nineteenth century. It is especially appropriate to do so in a book that reconsiders the Eureka story from unexpected angles in order to reflect generally upon the historical inheritance of the goldrushes upon Australian society.
Description:
Chinese immigrants and especially the Chinese on the goldfields of Victoria, now figure centrally in history curricula and in heritage and tourist promotions most prominently of course, through Bendigo’s Chinese Heritage Precinct and the Gum San Heritage Centre in Ararat. These public representations of nineteenth-century diversity draw equally from a reflexive, culturally-informed historiography and a radically transformed popular culture in Australia, Victoria in particular (Waterhouse 2009: 11–14). No doubt, when heritage analysis of the central goldfields was first systematised, following the Victorian Historic Buildings Act (1974) and a subsequent sequence of municipal conservation studies, the Chinese appeared as something of a curiosity, on the margins of the enterprise of mining and peripheral to the heritage of goldfields towns (Davison 1991). Only after decades of research and widening perceptions of what could be properly classed as heritage, has Chinese settlement emerged as critical to assessment and interpretation, and of course heritage tourism, within townships as well as in state forests and national parks. Perhaps coincidentally this interest in Chinese heritage parallels a revival of Chinese immigration to Australia, in a broad view, comparable to the peaks of the nineteenth-century gold era. And yet, in part because so many remnants of the work of Chinese settlers have been erased, and their intricate mining systems fragmented, these sites unintentionally revert to the status occupied years ago by their creators – as eccentric curiosities.
Description:
Grade control programs aim to deliver economic tonnes to the mill via accurate definition of ore and waste. The foundation of a successful program is high quality sampling supported by geology and a suitable data management and modelling system. Underground sampling methods include chip, channel and panel samples; grab/muck pile samples; and drill-based samples. Grade control strategy is related to mining method and orebody type. Sampling protocols must be designed to suit the style of mineralisation in question. Holistic studies focussing on ore mineralogy and gold particle deportment, size and distribution are required for sample collection and preparation protocol optimisation through 'Theory of Sampling' application. Where possible, such programs should be undertaken early in the life of a project. Appropriate assaying procedures are also required. Program implementation will require suitably skilled individuals to train and mentor staff, with ongoing Quality Assurance/Quality Control (QA/QC) monitoring and review will allow protocols and staff to be updated as required.
Description:
Complex gold deposits are generally characterised by variable geometries, strong structural controls on grade distribution and a high-nugget effect. The use of diamond drilling and fire assays in this environment often results in an understatement of grade. Bulk samples are likely to be the closest estimators of true grade, and may be required to evaluate geological/grade risk during resource estimation/feasibility studies. Any bulk sampling program requires appropriate planning and implementation. The planning stage should attempt to delimit the extent and nature of mineralisation; characterise mineralogy and metallurgical properties of the ore; and define bulk sample size and how it will be sampled/processed. The approach to sample processing will be governed by the results of metallurgical testing and geological knowledge. Careful design of sampling protocols must be undertaken through material characterisation, understanding of gold particle sizing and the application of Gy's Sampling Theory.
Description:
There is little evidence of Aboriginal involvement in the events of the Eureka Stockade, but there are numerous ways in which Aboriginal people are relevant to the Eureka story. The events took place on Aboriginal land (an obvious but rarely articulated truth) and Aboriginal people were present on the Ballarat diggings, as they were, indeed, on and around most Australian goldfields. The records are full of references to their fundamental and diverse contribution to life and work on the diggings, and to the complex and varied relationships they formed with the invaders. For Indigenous communities already reeling from the invasion of pastoralists, the arrival of 300,000 immigrant miners, swarming onto the alluvial districts of Victoria, represented a second wave of dispossession. But as we have noted elsewhere, there is abundant evidence that gold, at least in Victoria, brought many new economic opportunities for Aborigines, many of whom took advantage of these changed circumstances.' David Goodman argues persuasively for historians to consider an 'edgier interpretation' of the goldfields story. This could include a better appreciation of the social dislocation and cultural adaptations experienced by Indigenous people on the goldfields .