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By M.E. Crump

Gallium occurs at above background levels in most samples collected from 11 of the major geothermal areas in the Taupo Volcanic Zone. Concentrations of Ga in the 48 samples ranged from 8 to 144 mg kg-' and varies widely from place to place within each geothermal area. Gallium is contained within the alumino-silicate structure of clay in the mud, having substituted mainly for Al. Suggested deposition mechanisms for Ga also involve co-precipitation with Sb, As, and SiO. colloids. Digestion trials, carried out to determine extraction conditions for possible commercial exploitation, showed that heating the mud to 500 -600¦C for 1 hour followed by acid/alkali treatment gave complete recoveries.

Jan 1, 1995

For several years, the Geology Department of the University of Canterbury has hosted a series of postgraduate projects in the field of coal studies, supported principally by the Ministry of Energy and to a lesser extent by private companies. These projects have involved mainly West Coast Coalfields, and my own studies have focussed on inorganic geochemical aspects of West Coast coals. Because of the large number of potentially important analyte elements in coal, and the wide diversity of coals occurring in the West Coast region, this project has required a substantial amount of work to be spent on sample collection, sample preparation, development of analytical methods, and actual analysis. Considerable problems must be faced at the sampling stage: Can sufficient information be obtained from whole-seam composites, or should seams be sampled in plies. Ply analysis is preferable, but results of proximate analyses are usually available for composites only. Where multi-seam drillhole samples become available (eg Greymouth Coalfield, where some holes yielded more than six sampled seams), the ply option involves a dramatic increase in the number of samples. I have attempted to strike a workable compromise between geographical coverage of coalfields, and detailed sampling of individual seams at each locality. In many cases, sample material has been used jointly with Jane Newman who has carried out petrographic studies.

Jan 1, 1985

By Jacobs M

After a methane explosion in a coal mine a pre-determined crisis management procedure is instigated. As the process rapidly evolves the inevitable question arises - are personnel trapped underground, are they alive and can they be rescued without putting the lives of the rescue crew at risk? This is a very emotive question with many sub-questions such as; could anybody have survived, is there the potential for a secondary explosion and is there a `window of opportunity' before that secondary explosion occurs?To determine if that window of opportunity exists two fundamental elements must be in place; a method of determining the atmosphere at key points in the mine and a method of predicting the course of change of that atmosphere with respect to time. The first element can be achieved if the tube bundle system is intact and drawing samples from known points, alternatively boreholes can be drilled from the surface. The second element can be realised by utilising a sequence of computer generated control charts which have a time axis, a percentage combustibles axis, the upper and lower explosive limits of the current atmosphere and a prediction option which allows the user to look at the potential changes in the atmosphere over a set period of time. These control charts would be part of the mines on-going crisis management system rather than a tool to be used after an explosion had occurred.

Jan 1, 1998

By Prosser A. P

A computer simulation is being developed for in-situ leaching of unbroken, Zn-Pb-Ag sulphide ore. Ferric chloride is the selected reagent. Experimental work showed that a diffusion control model of the kinetic aspects was better than a surface chemical reaction control model. Entrapped reactive grains were accessible to reagent in the samples tested. Precipitated sulphur did not seriously hinder the reaction.

Jan 1, 1987

By B Bendtsen, L McQueen

The use of shotcrete as an efficient means of both temporary and permanent ground support has continued to grow over the last 30 years, with its use underground now commonplace around the world. However, the development of analytical design methods has lagged advances in material and application technologies. Historically, part of the reason for this was a lack of understanding of how shotcrete linings actually worked. Considerable progress has been made in this area in recent years and this paper attempts to summarise the current state of practice with respect to shotcrete lining design. It then concludes by summarising areas where the authors consider future research and development is still required.

Jan 1, 2008

By L C. Thompson

BioLix is the term for a new class of biologically-derived lixiviants for precious metals (gold and silver) recovery. BioLix can be used as an alternative to cyanide on virgin and spent ores. The BioLix process is based on inducing microbial enzymatic reactions that generate organo-lixiviant chemicals. The bioprocess involves a two-stage culture strategy. First, specialty microorganisms are cultured to generate a high biomass. Then, a food-grade quality amendment is introduced that forces the microorganisms to produce the organo-lixiviant. The second-stage culture is applied to the ore where the microbial/lixiviant system acts on mineral surfaces to extract precious metals. The process operates at ambient temperatures and near neutral pH. This paper will examine the BioLix process through an extensive laboratory development and demonstration project. Laboratory development consisted of identifying and isolating specialty microorganisms and inducing agents for the production of the organo-lixiviant solutions. A demonstration was performed on low-grade and high-grade oxidised ore from the Buffalo Valley mine in Nevada, USA. Results indicate that the BioLix process was comparable to cyanide in terms of gold recovery and operated at near neutral pH and ambient temperatures. Applications for the BioLix process will be discussed including spent-ore re-leaching, cyanide replacement for virgin ore, and in situ mining.

Jan 1, 2004

By Sinha NH

ICI Australia and CSIRO have developed a novel process for extraction of zirconia from zircon sands. The two stage process involves a high temperature step and a wet chemical processing step. A pilot plant has been operating since November 1985 at CSIRO Division of Mineral Chemistry, Port Melbourne and construction of a full scale plant isplanned at Kwinana, WA.The plant has a high degree of flexibility and is capable of producing high purity zirconia up to about 99.99% and withinspecific particle size ranges. The products are being marketed by the joint company, 2-TECH Pty Ltd.

Jan 1, 1986

By R L. Koenig

Previous papers at Metplant conferences have covered the options for crushing and grinding circuit selection. High Pressure Grinding Rolls (HPGR) may have considerable advantages over autogenous milling circuits but test work and evaluating different grinding circuits must be done to establish which circuit provides the best option. The Hawsons low grade magnetite project provides a specific example in using thorough test work, careful simulations and detail in design to allow the evaluation of grinding circuit performance. Fortunately tools are available for this evaluation and the test work for the Hawsons iron ore is detailed in this paper. The results of the test work and simulation indicates that although the Hawsons iron ore is competent in terms of autogenous milling given the medium hardness of the ore in the Drop Tests, the HPGR testing indicates that the use of HPGR is likely to use half the energy requirement. This is a characteristic of the Hawsons iron ore and is likely to be valid for other iron ores in the Braemer Iron Formation which stretches from the Hawsons lease in New South Wales to Razor Back and South Dam in South Australia. The Hawsons magnetite iron ore resource has been known from the early 1960s when CRA explored the area. However, the Pilbara region was discovered in this era and this led to development of high grade direct shipping grade hematite ores. Carpentaria Exploration (Capex) rediscovered the magnetite whilst undertaking multi-commodity exploration in the Broken Hill district during 2009. The magnetite grade was found to be low at around 16% Davis Tube mass recovery (DTR) but despite this, the project provides a positive business case as a result of the following key factors:• The mineralisation is particularly soft for crushing and grinding with a Bond Work Index of 6.3.• The mineralised rock fractures easily preferentially along grain boundaries.• The location is close to mining infrastructure and a skilled workforce in Broken Hill, 60km to the North East.• It is close to road and rail infrastructure for access to the resource.• The only contaminant in concentrate is silica.• The resource contains many billions of tonnes of magnetite mineralisation.The low Bond Work index is a key characteristic of the Hawsons iron ore and the use of autogenous milling and HPGR circuits is compared to other iron ores indicating why the plant energy requirement may be just as important as iron ore grades.

Aug 8, 2011

This paper discusses the significant land use changes that have occurred in the Latrobe Valley during 150 years of white occupation. The developments and changes were haphazard and made with little thought as to their setting or their environmental consequences. As a result many landscape and land management problems have not been addressed.This paper contends that the mistakes will continue unless an overall plan for the landscape of the area is developed and implemented. The concept of 'Greening the Valley' is introduced. It aims to provide focus for a comprehensive co-ordinated plan which caters for the need to restore the landscape and the need to provide for future land use. The plan will seek to draw on three major landscape features of the Latrobe Valley: the natural setting of the hills, rivers, valleys and forests; the agricultural land use including the forestry plantations; and the industrial complexes and urban areas.Rehabilitation of mining areas is a key element of the plan but must be put in a regional context and not be treated as an isolated function of a single organisation. A major challenge will be to integrate the worked out areas into useful and significant landscapes. The paper concludes by explaining the process that will be followed in an attempt to realise the concept.

Jan 1, 1992

Chemicals derived from petroleum raw materials satisfy so much of our industrial needs today that it is good to pause and realise two things -ò the petroleum chemical industry is so new, and the use of chemicals is a very old one.Petroleum is such an'abundant and convenient source of raw material that in little more than 30 years it has become the major source of supplyfor chemical rdanuf ctiree This paperw~l'l 'disc'uss t1.e main 'r`easons' for this rapid development by considering the : sub jest -under tkzree headings ea. Source of Raw Materials.b. The Impact of Petroleum Chemicals on Plant Design and Processes. ce Scme of the Major Chemicals Used Today.

Jan 1, 1962

This paper describes the technique developed by the Australian Coal Industry Research Laboratories (ACIRL) for the treatment of bore core samples to obtain data for coal preparation studies of the target reserves. The particle size distribution within the sample has a significant influence on the relationship between the yield and ash per cent of the floats coal at any ash level. The size analysis within the reconstituted feed from a coal preparation plant is determined by the size analysis of the feed coal, physical degradation of material in the process, and the breakdown of associated shales in water. The extent of material breakdown was studied in the ACIRL coal preparation pilot plants. The method of bore core evaluation includes simulation of this breakdown in a sample selectively crushed to conform with predicted or known run-of-mine size distribution. Modifications have also been made to the laboratory methods for froth flotation to approximate more closely with industrial practice.

Jan 1, 1977

By S C. Dominy

Current and proposed methods of resource classification relate to the geological, economic and technical confidence in the estimated resource. Geological confidence is, however, only vaguely defined. It is largely related to the level of drilling and sampling, to the geologistÆs perceived level of confidence in his/her work and on the continuity of the mineralisation. Rarely has any real attempt been made to assess how well a deposit has been explored, sampled and evaluated and how accurate or realistic the geological model is for the deposit. This contribution reviews the impact of two of the potential sources of error, ie sample recovery and quality. The first of these parameters is measured during logging and assaying, but is often forgotten during grade and tonnage estimation, and resource classification. Preliminary studies have shown that modelling of this parameter is a valid exercise, which should accompany the evaluation of grade and other economic parameters. The sample recovery factor for an ore block can then be used to reassess the confidence in the block. It could, for example, downgrade the status of a Measured Resource to an Indicated Resource even though standard methods might indicate that the higher classification is applicable. A method is proposed by which this recovery factor could be incorporated into current resource classifications producing a more sophisticated and comprehensive measure of sample quality. A review of the sources of error naturally leads to the assignment of scores to each stage of the evaluation process, depending on the methods used and assumptions made. Sample recovery is one important factor, which is likely to appear at several stages. These scores can then be weighted and combined in a manner resembling that used in the CSIR Rock Mass Classification. This score will then allow the resource estimate to be rated on a scale from 0 to 100 per cent to produce a Quality Control Index (QCI). However, this index must then be modified using an Evaluation Difficulty Index (EDI), which reflects the difficulty of a particular style of mineralisation to accurate resource estimation. This results in the production of a Resource Reliability Rating (RRR), which can then be linked to international classifications, such as the 1999 JORC; 2000 CIM; and 2001 EURO codes. This will permit a more precise definition of geological confidence levels or, combined with estimation error, produce a classification system in its own right. This same rating can also be used as the basis for technical audits of mineral projects.

Jan 1, 2002

By P Allum

This paper presents a case study to reduce the operational cost on the secondary ball mill circuit in the Lead/Zinc Concentrator at Mount Isa Mines. The circuit includes two five-metre diameter ball mills each closed with a cluster of ten 15-inch cyclones. The operating cost for both ball mills is about six million Australian dollars per annum.The concentrator achieves 75 per cent of the plant design capacity with one ball mill operating, but will have to use two ball mills when 100 per cent plant capacity is required. The optimisation study on the circuit identified a new flowsheet that enabled the concentrator to reach 100 per cent of the capacity by using one of the two secondary ball mills. The success of the project utilised the existing equipment rationally and saved the operational cost for one ball mill at full concentrator capacity. A further simplified secondary circuit is proposed using the IsaMill for the secondary grinding duty. Performance of the IsaMill circuit and the potential cost savings are predicted.

Jan 1, 2002

By Paine G. G

The measurement of the fragmentation size distribution of a blast muckpile can be achieved directly by screening the entire muckpile. Screening of muckpiles in a production operation is generally not practical due to the logistics and time involved moving large volumes of rock through a screening plant. An indirect technique to assess blast fragmentation size distributions has been developed. This technique uses photographs of the blast muckpile taken at intervals during the excavation cycle. The images from the photographs are input to desktop computer software via a digitiser tablet. The software compilates the rock fragment sizes and calculates a size distribution. This paper discusses the technique and subsequent data analysis. Examples of the application of this technique for the assessment of comparative blast performance are given.

Jan 1, 1990

By R Brake

The Enterprise Mine Project (EMP) is being developed by Mount IsaMines Limited as the future source of copper ore at the Mt Isa miningand processing complex. Environmental engineering is one of the majortechnical challenges facing the project because of the depth of theorebodies, high virgin rock temperatures and hot ambient surfacetemperatures in summer. This paper discusses the engineering principles adopted by EMP to manage the risks associated with working in these adverse thermal conditions.

Jan 1, 1998

By B Tadesse, L G. Dyer, K Ward

The Golden Mile ore deposit in Western Australia is one of the largest gold telluride deposits in the world. Approximately 20 per cent of the contained gold in the deposit is present as gold telluride minerals, the most prevalent being calaverite (AuTe2) and petzite (Ag3AuTe2). Telluride mineralogy in the Golden Mile orebody is fine grained and complex having formed due to hydrothermal deposition in the late paragenetic sequence. Nineteen tellurium bearing minerals have been identified including gold and silver as well as mercury, lead and nickel tellurides (Shackleton, Spry and Bateman, 2003). Extensive work has been completed on the flotation of gold, gold-silver alloys and gold ores however there is a lack of information detailing the difference between flotation of native gold and individual gold minerals (Dunne, 2016). Studies on the flotation behaviour of gold ores have focused primarily on the flotation of free gold and refractory sulfides (Teague, Van Deventer and Swaminathan, 1999).

Aug 24, 2022

By Olden WH

A scheme is presented whereby the complexities of design and operation of a hydraulically powered coalmine support are modelled using the finite element method. This enables predictions to be made of the interaction of the support with its environment in a variety of operating conditions. The model is a two dimensional representation. The modelling scheme was applied in two case studies. In the first, the performance of a four leg support was uprated by increasing the front leg force. The finite element model enabled changes in overall support performance to be verified. In the second case study, the change in lateral force developed by a two leg support was assessed with changes in support operating height and floor foundation stiffness. The modelling scheme is capable of further development with the possibility of extending the model into three dimensions and the addition of control elements that would enable an actual mining sequence to be Represented.

Jan 1, 1992

By Bhattacharyya A. K

A strata parameter is introduced to include the deformation characteristics of the undermined strata in the prediction of subsidence movement. By using the strata parameter and mining factors as parameters, a nomogram for predicting the maximu

Jan 1, 1994

The weathering of different types of base metal deposits in the semi-arid environment of the Lachlan Fold Belt of western New South Wales affects the geochemistry of outcropping ironstones (gossans) and derived soils. W eathering of the pyrite- and pyrrhotite-rich mineralisation at the Elura Zn-Pb-Ag deposit leads to highly acidic conditions and strong depletion of Cd and Zn throughout the profile. There are local attainments of high concentrations of Ag, As, Ba, Cu, Hg, Pb, Sb and Sn in the profile and As, Ba, Pb and Sb are still highly anomalous in surficial material (ironstone and soil). However, at Parkers Hill, in the Mineral Hill Field, the primary Zn-Pb mineralisation is pyrite-poor and so weathering is not as acidic as at Elura. Thus, although Ag, As, Cd, Cu, Sb and Zn may be concentrated at various levels in the Parkers Hill weathering profile, Cu and Zn (as well as As, Pb and Sb) are retained in surficial ironstones in essentially the same abundances as in primary mineralisation. Thus, variations in the suite of geochemical indicators present in ironstones and residual soils are likely to reflect differences in the original mineralogy and the degree of acidity produced during the weathering of base metal mineralisation. Hence, an understanding of weathering processes is necessary to fully interpret exploration geochemical data.

Jan 1, 2004

It is now 32 years since Walsh's classic publication (1) heralded the beginning of atomic absorption spectrophotometry (AA) as we know it today. During this time, AA has developed into the most widely used analytical techniques for the determination of the metallic elements. The years have seen progressive changes in instrumentation so that today it is a highly sophisticated technique. One area of development in AA that is experiencing renewed attention is in the area of electrothermal excitation. In this technique a flame is not used by the analyte solution is atomised by an electrically heated graphite furnace. For a large number of elements the graphite furnace atomic absorption spectrophotometer (GFAA) is considerably more sensitive than flame work. It is common to be able to detect concentrations one hundred times smaller than those possible by flame. Today's geochemists are finding that they can gain valuable information out of very low limits of detection. Electrothermal atomic absorption spectrophotometry (or GFAA) allows for low limits of detection and can be seen to be a valuable aid to geochemical prospecting Analysis.

Jan 1, 1987