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Dr Eric Bumstead is to be commended for his recent paper on gold analysis, published in the March 1984 Proceedings. It is not often that someone in industry, rather than academia, takes the time to collect and report on such a volume of data, data which is of interest to everyone involved in gold exploration and development.After reading the paper I felt, as a geochemist and as ayer, that there was another side to this whole question of analysis that few people are aware of, i.e. the problem facing a laboratory and how the laboratory can try to give the customer maximum value for money spent.Analyses for gold are carried out for different reasons, depending on the aims of the geologist or metallurgist who presents the samples. These can broadly be separated into three classes, to answer the following questions.1. "Is there any gold in this sample?"2. "Approximately how much gold is there in this sample?"3. "How much gold is there in this sample?"In every case there is a different balance between accuracy and precision, cost and avoiding chemical problems. By "chemical problems", I mean such possibilities as samples containing high levels of sulphides, gold present as tellurides, cyanide being present, contamination with mercury, and other mineralogical oddities, plus problems such as samples containing grease.There is no such thing as one assay to cover all possibilities.Samples in category I come mostly from early stages of exploration.There are often large numbers of samples, their mineralogy is not well known and hence chemical problems could exist, but the explorer wants assays at a minimum level of precision and expects minimum cost. These characteristics do not easily come together, for although the precision required is low, the accuracy required is high at low levels. A small positive result when the true answer is nil could lead to a fruitless search and a waste of money. Conversely, a nil result, when the true answer is a small but significant level of gold, could lead to the passing over of an area that may warrant further work.Because there are conflicting requirements for this type of assay, the methods chosen must be a compromise and different assayers will balance these requirements differently and come to different conclusions. The methods cover sample preparation, assay sample size and variations in assay techniques.

Jan 1, 1984

The Mt. Sisa Orebody on Misima Island, P.N.G., consists of gold-silver mineralization associated with massive carbonate and amor- phous iron-manganese oxides in fractures and breccia matrix. The orebody forms the north- ern extension of the Umuna deposit. The mineralization lies within the three kilometre strike length of a northwest trending, 300 metre wide, high angle fault zone. The fault zone structure is deeply oxidi- sed, with the manganiferous oxide material resulting from oxidation of carbonate. The wallrocks are metamorphosed basement psammopelites and basic volcanic rocks, exten- sively intruded by microgranodiorite. These are dominantly epidotized and sericitized. The precious metals are associated with anomalous Cu, Zn, Pb, Mn, As, Ba, Ga, Sb, and. Mo. Many of the features of the Mt.Sisa mineralization are characteristic of volcanic- hosted epithermal deposits of western North' America. Lithologic and textural gradation is ob- served between the carbonate hydrothermal breccia-fill at Mt. Sisa, and the quartz domi- nated dilational fracture-fill mineralization which forms most of the Umuna deposit to the south. This gradational relationship is ana- logous to that within the Amethyst-OH vein system at Creede, Colorado, where it is shown to be indicative of deposition from laterally migrating fluids.

Jan 1, 1987

By White L. R, Boger D. V

The paper describes the surface chemistry and particle physics that control the fundamental flow properties (Theology) of mineral particle slurries. We further address, through a series of case studies, the design data that emerges from experimental studies of the flow properties of complex, high volume fraction mineral slurries. The case studies are drawn from mineral oxide concentrate processes, tailings dewatering operations and from filter cake production and management. The paper emphasises the essential links between design of process slurry handling systems and the control of the flow of such slurries by control of the pulp chemistry.

Jan 1, 1992

By T C. McCuaig, D B. Mapleson

The Wannaway Deposit is a structurally modified komatiite-hosted nickel-sulfide deposit. Until recently, nickel sulfide accumulations surrounding the Widgiemooltha Dome had been studied with a focus on understanding volcanological aspects of komatiite flow regimes and nickel-sulfide accumulation. Although volcanological features can be observed at Wannaway they are overprinted by several generations of structures associated with multi-phase deformation of the Dome. On the mine scale, two significant deformational events can be distinguished that control ore distribution. The first deformational event is represented by the formation of a layer parallel foliation within the footwall metabasalt and boudinaging of the ore into two distinct orebodies (mega boudins) during a north-south compressional event. Evidence of a second compressional event (east-northeast-south-southwest) is defined by reverse > dextral thrust-folding of the ore zone. The latter deformational event focussed the sulfide ore into thrust front positions where folded ore sequences are mined with stope widths up to nine metres wide. Later stage compressional and extensional deformation phases are observed but have minor, localised effects on the geometry of the ore zone. Four orders of control on the geometry and distribution of ore are interpreted through a combination of primary and secondary features observed at Wannaway. Extending the structural aspects of the secondary overprint features into areas of potential mineralisation has not only defined targets for extensions to the Wannaway Deposit, but has also aided to delineate high grade mineralisation and aid mining decisions. Obtaining an understanding of the volcanological conditions of formation, and more importantly, the structural evolution of the Wannaway region has been an integral part in optimising production.

Jan 1, 2003

By Szwedzicki T, Jiang J

The acoustic emission (AE) technique has found wide application in rock engineering. Generally, acoustic emission, which is produced by a rapid microcrack growth, is an ubiquitous phenomenon associated with brittle fractures and can provide information on the failure process in rocks. The sudden release of stored energy in the form of an elastic stress wave that travels from the point of origin within the material to a boundary is called an AE signal or a discrete AE event. Based on a number of experiments and analysis, the correlations among the rock type, the complete stress-strain behaviour, mode of failure and AE properties are investigated and the AE pattern has been classified as four types: single-peak AE, double-peak AE, continuous AE and absent AE. Each type of AE pattern corresponds to a certain type of rock and is largely related to the internal structure and imperfection of a rock. Applications of the AE technique in stability monitoring, in situ stress assessment and seismic source location are also discussed.

Jan 1, 1995

By A Fareth

Constructed between 1885 and 1891, the New Croton Aqueduct (NCA) in New York State is a 50 km long (31 mi) brick-lined tunnel conveying water from the Croton watershed north of New York City to distribution systems in the Bronx and Manhattan. Except at two siphons, the aqueduct operates as an open channel conduit from the New Croton Reservoir downstream 39 km (25 mi) to the Jerome Park Reservoir in the Bronx. The remaining 11 km (6 mi) is operated as a pressurised conduit and includes a major siphon, of circular cross-section, under the Harlem River. The aqueduct has a flow capacity of approximately 1100 million litres of water per day (13 m3/s or 290 million gallons per day) and supplies on average ten per cent of New York CityÆs drinking water. The CityÆs water supply system is operated and maintained by the New York City Department of Environmental Protection (NYCDEP). This paper covers the work done during the three main stages of the program to rehabilitate the entire NCA: inspections, design and rehabilitation. It also includes some of the more interesting structural findings of the original construction as well as documents and drawings from the NYCDEP archives. The rehabilitation program has been underway in phases since 1993, with inspections scheduled to minimise outages, allowing this strategic aqueduct to remain in service during critical seasonal periods. The open channel flow section of the aqueduct in the north is horseshoe shaped, with inside dimensions of 4.1 m (13.6 ft) in width and 4 m (13.5 ft) in height. The pressurised section is 3.7 m (12.3 ft) in diameter, and includes a 90 m (330 ft) deep siphon under the Harlem River. A total of 163 million bricks were used in the construction, enough to build a 48 km (30 mi) wall around Manhattan Island, 3 m (10 ft) thick and 15 m (50 ft) high.Between 1993 and 1997 a series of in-tunnel investigations were performed in the open channel portion of the NCA, consisting of field inspection, non-destructive geophysical testing, and coring of the brick liner. Between November 2004 and September 2005, a major inspection program was conducted to assess the condition of the 11 km (6 mi) long pressurised section and all shafts, headhouses and blow-off structures along the entire 50 km (31 mi) alignment. Inspection methods included using an underwater remote operated vehicle (ROV) equipped with sonar and cameras to inspect the deep siphon, fibre optics examinations of probe holes drilled through and beyond the brick lining, and core holes and geophysical inspections to assess properties of the liner and behind-the-liner materials. A water pressure and test grouting program was conducted to assess methods and expected grout takes for the rehabilitation work in the pressurised sections. The rehabilitation program is anticipated to be completed in 2010.

Jan 1, 2008

By P N. Duan, Z G. Liu, M S. Chu, X X. Xue, B Liu, G J. Cheng, T Jiang, J X. Liu

High-chromium vanadium-titanium magnetite has not been exploited and made full use of on a large scale so far due to the immature utilisation technology and the reality that the utilisation efficiency of valuable metals still urgently needs to be improved. In the present paper, the isothermal reduction kinetics and mechanism of high-chromium vanadium-titanium pellets were studied at 800–1100°C. The mineral composition transformation of pellets before and after reduction was analysed by means of X-ray diffraction (XRD), and the microstructures were examined by scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) to reveal the elemental distributions. The effect of reduction temperature on the volumetric swelling degree and cold crushing strength was also studied. It was found that reduction temperature has a large effect on the reduction rate of pellets, and the increase in reduction rate is more obvious in the range 1000–1100°C than 800–1000°C. The volumetric swelling degree of pellets increased with increasing reduction temperature, while the cold crushing strength decreased. The transformation of mineral species can be expressed as Fe2O3 ? Fe3O4 ? FeO ? Fe, Fe2O3·3TiO2 ? Fe3O4· (2FeO·TiO2 ) ? 2FeO· TiO2 ? FeO·TiO2, (Fe0.6Cr0.4)2O3 ? FeO· Cr2O3 ? Cr2O3 , and Fe2O3· VO/V2O3 ? VO. The apparent activation energy of the reduction reaction was calculated to be 44.3 kJ/mol, and the reduction rate is controlled by the combined effect of interfacial chemical reaction and gas diffusion through the porous product layer. The rate controlling steps were further studied by calculating the resistance percentages. The interfacial chemical reaction was found to be predominant in the initial reduction stage, with the percentage effect of gas diffusion through the porous product layer gradually increasing during reduction.CITATION:Cheng, G J, Xue, X X, Liu, J X, Liu, Z G, Chu, M S, Jiang, T, Liu, B and Duan, P N, 2015. Reduction kinetics and mechanism of pellets prepared from high-chromium vanadium-titanium magnetite concentrate, in Proceedings Iron Ore 2015, pp 349–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

This brief introduction tries to introduce delegates to this conference to the almost unbelievable attributes possessed by many microbes which might be relevant to geomicrobiology, and how most of these remain unexploited by us. It introduces some of the terminology which will be used and tries to suggest that there are rewarding times for those who set out to discover the natural biodiversity of bacteria in nature. Although we have exploited microbes, usually unwittingly, and suffered at their hands for millennia, it is only recently that we have begun to become aware of how they dominate our planet (most of the earthÆs biomass is bacterial) and are responsible consequently for most of what happens here. A few can cause us harm and occasionally kill us, but most bacteria are beneficial, impacting positively for example on how we grow our food and in cleaning up the pollution we create. They are simply indispensable to how we live. They have been responsible for many of the geochemical changes which have taken place on this planet and play major roles in the transformation of elements so essential to our existence (Newman and Banfield, 2002). No one should dismiss them as minor players in our game of life.

Jan 1, 2004

By Muir D. M

Highly saline process water has a number of implications for the CIP process during the leaching, adsorption and recovery of gold. The reduced oxygen solubility in saline water can seriously reduce the rate of gold leaching, while dissolved oxygen meters do not necessarily reveal actual oxygen concentrations in saline water. High levels of magnesium in the ground water necessitate operation at lower pH (-9), with the potential for greater cyanide loss via HCN stripping. In addition increasing salinity renders viscosity modifiers largely ineffective.The adsorption capacity of aurocyanide onto activated carbon is improved with increasing salinity, but misleading results can be obtained in assessment of gold loading kinetics of plant carbon samples already loaded, or partially loaded, in saline water if subsequently tested in fresh water. Elevated chloride levels in the Zadra elution process can cause severe anode corrosion in the elecuowinning cell. The Anglo elution process is tolerant to only slight increases in water salinity, but elution times can be reduced by ethanol addition. Care is required in carbon regeneration, as salts can catalyse carbon decomposition as well as increase kiln corrosion.

Jan 1, 1994

Optimisation and sensitivity analysis of final pit limits is now an accepted procedure for open pit planning studies. Tools to assist the design engineer in an underground metalliferous mine to make optimal choices for the selection of major development, stope geometry and cut-off grade analysis have not been available. The engineer has had to rely on experience and a limited analysis of design alternatives. A new tool called the `floating stope' has been developed to define the optimal (boundary) limit for material that can be economically extracted by underground stoping methods. The method is analogous to the `floating cone' method of open pit optimisation. The geology and mineralisation are modelled as a regular or subcell block model. Included in the model are structural and geotechnical features, and any previously mined out areas. Inputs to the procedure include the minimum stope dimensions, cut-off grade, stope head grade, and the way in which dilution is to be calculated. The optimisation procedure can be directed to maximise ore tonnes, grade, contained metal or the economic (dollar) value of material mined. The procedure can be applied at each stage of mine evaluation and design to assist with preliminary resource appraisal, selection of stoping methods, and detailed mine design. As with open pit optimisation procedures, manual intervention by an experienced engineer is required to produce practical and detailed designs. This practical design should follow the optimised design as closely as possible. The paper outlines the algorithms used in the definition of the stope envelope, and describes the analysis and results of several case studies where the optimisation procedure has been applied.

Jan 1, 1995

By Aziz N. I

Examination of the geology and support performance at two site leads to development of an under tanding of the influence of caving on powered support rating. The two site represent the current extremes in support rating, i.e. 6/260 tonne supports operating in the Hirst seam at Solsgirth Colliery, Scotland, and 4/900 tonne supports operating in the Bulli seam, West Cliff Colliery, Australia.A conceptual model considers the coal ahead of the face, the powered support, and the caved waste to be three yielding foundations which interact to control the subsidence of the roof strata.The caving mechanisms identified for the strata of the Hirst and Bulli seams, are different. These mechanisms being related to rock properties - the palaegeography and depositional conditions at each site-produce caved wastes with different yield characteristics.An analysis of the results obtained for convergence and support reaction during production cycles at both sites shows the manner in which support reaction is developed, indicating the importance of higher setting load densities in the Bulli seam.Evaluation of the work done on the subsiding roof strata during typical production cycles by two of the yielding foundations the powered support and the caved waste immediately behind the powered support - further demonstrates the influence of caving mechanisms on support rating.

Jan 1, 1989

By I T. Ross

Sampling drawpoints in block cave mines has been a contentious issue for many years. Doubts have been expressed as to the validity of the process used at most mines. This paper outlines the sampling practice commonly in use, discusses the resulting issues associated with reconciliation and drawpoint closure decisions. The paper also looks to the future and highlights issues for some block cave mining operations currently planned to have in the order of one thousand active drawpoints. It is likely that these operations will require a new approach to drawpoint sampling. There are several potential technologies currently available although some appear to be better suited than others to replace the current approaches. CITATION:Ross, I T, 2012. Sampling in block cave mines, in Proceedings Sampling 2012 , pp 81-86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By H F. Galbiatti, G J. I dos Santos, A de C Zapparoli

The Grao Para and Rio Maria greenstone banded iron formations (BIFs), within the Carajas mineral province, exhibit distinct lithological and petrographic fabrics, together with pronounced differences in their surface expression, real thickness, iron grade and tonnage. These geological differences support a new model for the regional distribution of iron formations in the Carajas Mineral Province.

Jan 1, 2009

By G H. Park, Y J. Jun, J H. Park

The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag, the main system formed in the Ruhrstahl-Heraeus (RH) vacuum degasser, was measured at 1873 K to understand the effect of slag compositions on the carbon contamination in the ultra-low carbon (ULC) steels. The stable form of carbon was demonstrated to be carbonate by plotting the log [(wt%C)/aC] ratio against the log p(O2) which ranged -11 < log p(O2,atm) < -9. The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag can be estimated using thermodynamic model. The distribution ratio of carbon increased with increasing concentration of FeO due to the FeO reduction reaction and increased basicity of slag. The carbonate capacity of the CaO-Al2O3-FeO-SiO2-MgO slag can be expressed as a linear function of the activity of lime and the optical basicity.

Jun 19, 2024

By M McLean

This paper deals with change strategies on brownfield and greenfield sites in extractive industries. It draws upon contemporary experiences across Australian, Indonesia and Papua New Guinea (PNG). Change strategies can be used when owners of an extractive industry operation want to optimise their resource. This paper draws upon many tried and proven theories and practices, including the findings of the Tavistock Institute (Trist, Emmery, Bamford, Jaques), as well as the concepts of Adult Learning espoused by Malcolm Knowles and is supported by learnings of Australian based management consultants. This paper reviews a range of approaches that have succeeded in the integration of systems, machines and people, with the key corporate objectives of: increasing productivity; decreasing cost; improving on-time delivery performance and achieving long-term survival. Such integration needs to be measured to show the outcomes from the change strategies and the authors have worked within many measurement regimes and metrics but for the most part, found that JaquesÆ set of metrics being æquality, quantity, resources and timeÆ has gained currency across many Australian operations. This paper contends that investing money in machines alone without a commensurate investment into the people side is counter-productive. Further, if there is not an understanding of processes, ie stable and capable, core and support processes, then all that new technologies will do, is to make what is done badly, only quicker. Recent interventions for the most part, have been cognisant of this balanced approach towards change management. The change strategies described are across extractive industry implementations, using a number of tools and techniques drawn from Continuous Improvement and Six SigmaÖ (registered trade and service mark of Motorola Corporation, USA).

Jan 1, 2006

By Pollmans GJ, Hoberg H, Schneider FU

The Institute of Mineral Processing at Aachen University of Technology has been engaged in fine and ultrafine comminution for several years. Former investigations had been dealing with the mechanical activation with the aim of increasing the solubility of highly resistant oxides such as tantalite and niobite while research on the product of ultrafine powders is of major importance at the moment. Materials of that kind are of increasing interest in the production of extremely resistant ceramics, in the development of new raw materials, in powder metallurgy and in the production of fillers (extender pigments) and pigments. The creation of ultrafine powders is difficult and very expensive. They can be produced by means of condensation or dispersion methods. One important method of dispersion is mechanical comminution. Due to long and intensive research and development all over the world important advances have been achieved but still a great number of questions and problems occur especially in producing materials of submicron and nanometer grain sizes which could be answered or solved only insufficiently up to now. These mentioned difficulties refer especially to: ò the required energy input into the feed material, ò the forming of strong agglomerates and wall stickings, ò the required product qualities, and ò the entire and reliable characterisation of the products. Basic investigation aim to clarify the micro and macro processes of ultrafine grinding and work towards solutions to the difficulties mentioned above. The aim of the Institute&apos;s research is the development of a new grinding device for producing ultrafine powders. First results of a laboratory scale mill of that type will be presented in this paper.

Jan 1, 1993

The able address on the currency question given by the Right Honorable A. J. Balfour, M.P., late leader of the Government, at the Mansion House lately, before a large and influential audience, will strike a key-note that will resound throughout the world. It is high time that gentlemen of position and influence should come forward and express their views on this subject, so as to cause the matter to be,more seriously considered than it has been. The question can be no longer ignored or treated with indifference by bankers, financiers, merchants, miners, and others interested in the settlment on some basis the relative values gold and silver bear to each other. It is gratifying to not that such a great leader of political opinion as Mr. Balfour has given serious attention to this important question.The address created a deep impression ,on the minds of many who probably had not given the matter much att.ention, and Mr. Balfour&apos;s words will re-echo over a wide range of thought with such effect that I have no doubt they will materially help to check the downward tendency of the value and uses of silver. As a mining engineer, interested in the development of our mining resources for increasing gold aud silver for currency, and having devoted much attention to the subject, I cordially approve of the views set forth by Mr. Balfouf, and I think the general body of all interested in the production of gold and silver will do the same.

Standard petrographic profiles for many Permian seams from New South Wales and Queensland have been drawn up. The standard profiles of seams of the same age and from one or more coalfields were used to compile an idealized or type seam sequence for those coals in which more than half the seam profiles were similar to one another. A marked similarity existed between at least 7 of the 10 type seam sequences formed. The configurations of the vitrite-plus-clarite contents of the plies of 95 per cent of the seams could be formed from different arrangements of 3 basic sequences: (i) a two-ply sequence with a lower vitrite-rich and an upper vitrite-poor ply; (ii) a two-ply sequence with a lower vitrite-poor and an upper vitrite-rich ply; and (iii) a four-ply sequence of 3 plies with vitrite-plus- clarite decreasing upwards, terminating in a vitrite- rich ply. The third basic sequence was very similar to a succession described for some British Carboniferous coals. Eighty per cent of the Australian Permian coal seams studied began with the first (i) basic type of sequence and are interpreted as originating in peat- forming areas which became progressively drier. More than half the seams were formed in an area with a stable depositional surface level which was subject to oscillations of small amplitude.. Many (30%) were formed in an area with a steadily rising depositional surface level.

Jan 1, 1969

IN carrying out experiments to determine the amount of metal taken away by fume or fine dust the apparatus used requires to be strong and compact, as it is generaIIy necessary to work on a staging fixed at considerable distance above the ground and against a smoke stack or flue. It is essential that the test be carried out at a part of the stack welI away from any bends, to prevent eddies. The method described below has been used for estimating the dust losses from Dwight &amp; Lloyd sintering machines, antimony drossing furnaces, pot sintering trials, etc., and has been founc! satisfaetory. It is welI to bear in mind that the longer the period over which dust coIIection is extended, the more valuable the result is likely to be. The rateof aspiration of the gases through the apparatus is kept as regular as possible by changing the filter thimbles frequently, and the rate of flow should correspond closely with the rate of flow of the gases up the stack.The apparatus required for carrying out a test is as folIows :-{a) Thermometers : two are required, one for taking the temperature of the gas in the stack and one for giving the temperature of the gas in the aspirating drum. If the temperature in the stack is over 400&#176; C., it is advisable to use a pyrometer such as the &quot;Bristol&quot; the couple being standardized before use at about the temperature of the stack.(b) Pilot Tube: The foIIowing sketch (Fig. 1) iIIustrates the principle of the pitot tube. The readings are to be taken in a straight flue, or stack, preferably 20 diam. away from any bend. A, which is open, faces the air current and...

Jan 1, 1922

By I Ritchie, G Lane, C Morley, D Yataco

Marcobre SAC (Marcobre) is developing the Mina Justa project in Peru. The project has a lower grade oxide orebody overlaying the higher grade sulfide orebody. The oxide ore is treated by acid leaching; consumption of acid is high and is managed by vat leaching rather than the more conventional heap leaching process.The leaching process uses ore crushed to 100% passing 8 mm to optimise copper recovery. Acid consumption generally increases with a higher proportion of fines. Marcobre is investigating a three-stage crushing circuit with high pressure grinding rolls (HPGR) in the third stage, instead of the more conventional four-stage cone crushing circuit. The use of HPGR can result in higher fines production due to the higher compression forces in the crushing zone. This paper reports on the outcomes of the test work completed by Marcobre in 2016 and 2017 to manage fines production and compare the use of HPGR with conventional crushing on a high acid consuming ore.At moderate pressing forces, a HPGR crushing circuit appeared to produce similar size distributions to cone crushing. On average, both the copper recovery and the acid consumption in subsequent vat leaching were higher with HPGR crushing than with cone crushing.CITATION:Lane, G, Morley, C, Yataco, D and Ritchie, I, 2017. Are there differences in size distribution when comparing conventional crushing and HPGR?, in Proceedings MetPlant 2017, pp 60–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017