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Traditional methods for calibrating the most customisable forms of GyÆs formula for the prediction of sampling variances involve a large amount of experimental work. This work is often extremely sensitive to outlier treatment and often relies on assumptions. A general methodology called æthe consistency methodÆ, however, has proven efficient in guiding these critical steps and adding objectivity to these subjective tasks. After a quick exposition of its principle, it is shown how it can also be used to reduce the amount of experimental work when dictated by budgets.

Jan 1, 2008

Notwithstanding full concurrence with the dictum of a famous scientist that "definitions are the most accursed of all things on the face of the earth," in view of the considerable confusion which exists in jigging nomenclature, it is considered advisable to commence this paper with the following explanations of the terms which will be used throughout the text.Jig Bed. The whole layer of material lying on top of the jig screen.Ragging. The layer of denser material lying immediately above the jig screen, which is too coarse to pass through this screen and is confined horizontally by the cells of the top grid.Ore Column. The layer of ore pulp between the ragging and the top-water.Top Water. The water, carrying fine material in suspension, which flOiWS over the surface of the jig bed.Hutch Water. The water added to the jig below the screen. (Except for the water discharged with the hutch concentrate, the "hutch-water" eventually becomes "top-water.")Feed Water. The water in the ore pulp fed to the jig.(This water becomes part of the "top-water.")Pulsion. The period of the jigging cycle during which the water is moving upwards relative to the particles in the jig bed.

Jan 1, 1937

By Tripathy A. K, Satapathy B. K, Nayak B, Mohanty J. N, Dey D. N

The paper deals with the metallographic tudy of heat treated chromite and chromite-coke composite briquettes. The briquettes, prepared from chromite concentrate of Orissa Mines using molasses-lime, dextrinelime and tamarind seed as binders, were subjected to different temperatures and examined metallographically. The change of phase with temperature was analysed by X-ray diffraction.

Jan 1, 1987

Selective continuous surface mining is a rapidly developing system of mining which will have a significant impact on many present and future open cut mines. In many aspects the technology is in its infancy, whilst in other facets concepts drawn from other sectors of engineering are well proven. Full development of the potential and benefits of this technology will only be achieved if the mining companies and manufacturing companies work together to produce machines which the end user really wants.

Jan 1, 1986

By Cooke D, Large R

The Cambrian structure in the Mt Read Volcanics was produced by four deformational events: obduction of forearc-derived mafic/ultramalic complexes in the early Middle Cambrian, a middle Middle Cambrian extensional phase related to the post-collisional Mt Read volcanism and VHMS mineralisation, Middle Cambrian E-W folding, and Late Cambrian N-S folding and basin inversion. The major phase of VHMS mineralisation in western Tasmania is restricted to the very brief period of extensional tectonics within the middle Middle Cambrian. Within this period a N-S graben was produced with a complex series of transfer zones, largely striking E-W. Most VHMS mineralisation is restricted to the top of massive volcanic successions, with several mines close to Cambrian transfer structures. Many of the transfer structures continued to be active until the Devonian. The later compressional Cambrian events are not significant in localising orc formation. Within the Rosebery mine a complex pattern of minor Cambrian normal faults has a second order control on the distribution of the mineralisation.

Jan 1, 1997

By Dixon D. R, Sparrow G. J

Pressure leach liquors from the pressure oxidation of a bulk flotation concentrate prepared from a complex Cu-Pb-Zn sulphide ore were treated to remove iron, either by pressure oxidation (the Hematite process) or with particles of magnetite (the Magnetite process), followed by cementation of various metals with zinc dust to obtain a purified solution from which zinc was electrowon. Satisfactory iron removal was achieved by both processes after neutralisation to pH 4.5 or 5.5. Pressure oxidation of the liquor at 200¦C and 690 kPa oxygen overpressure, conditions similar to those of the Hematite process used in the zinc industry, resulted in the precipitation of the iron as hematite. With the Magnetite process, an iron hydroxide was precipitated onto magnetite at atmospheric pressure and ambient temperature and removed by a magnetic separation step. The performances of both these processes for the removal of iron are compared. It is concluded that the Magnetite process offers considerable cost savings. Other impurities, in particular arsenic, were also removed with the iron in both processes. Cementation at pH 5.2 and 85-90 ¦C with 3.5 g/L zinc dust reduced the levels of copper, cadmium, and nickel to a satisfactory level and subsequent electrolysis in a laboratory cell gave an acceptable deposit of zinc.

Jan 1, 1989

Ladies and gentlemen, distinguished guests and fellow members of The AusIMM, good morning.   Thank you for the opportunity to address you all today, Crown Minerals are very pleased to be associated with the conference again this year, and I commend the committee on their organisation and delivery of this yearÆs event.   As you can see from the topic of my discussion, I would like to broach the subject of collaboration between ourselves û Crown Minerals û and you our clients, and convince you that we are on the right track but can each do more.

Jan 1, 2007

By J-P Franzidis, M Esvelt, E V. Manla

The Floatability Characterisation Test Rig (FCTR) is a self-contained, highly instrumented, mobile pilot plant that is able to treat up to 2 tph solids. It consists of a bank of six 130 L WEMCO« SmartCells« and a bank of six 50 L WEMCO« SmartCells«. It was developed as part of the AMIRA P9 Project, primarily to determine ore floatability characteristics and to develop and validate flotation plant modelling, scale-up and simulation methodologies. However, it may also be used to carry out pilot-scale flotation test work. This paper briefly describes the circuit modelling, simulation and scale-up test work performed using the FCTR and the use of the FCTR in pilot-plant test work performed by the metallurgical staff at WMCÆs Kambalda Nickel Operations and Mount Keith Nickel Operation. At both Kambalda and Mount Keith the FCTR was found to be very flexible and straightforward to run, with an easily changeable circuit configuration and stable operation. Testwork was facilitated through having full stream sampling on all streams, and a high degree of instrumentation providing accurate measurement of process variables. The results obtained from the FCTR testwork were highly repeatable. As a consequence of using the FCTR, WMCÆs Kambalda Operation and Mt Keith Operation were able to complete a rigorous programme of pilot plant testwork more quickly than in the past, and with a high degree of confidence in the results.

Jan 1, 2003

By S Brown

With oxygen conditioning routinely used in both the lead and zinc circuits at Pasminco Elura Mine a more sophisticated method of determining oxygen demand was required. It is known that different ore types have different oxygen consumption rates, however oxygen is added at a fixed rate regardless of ore type in the plant. Therefore, a simple laboratory test was devised to measure the oxygen demand of ores. The paper describes the technique employed, and provides an interpretation of the results. These data, together with pulp chemical measurements (Eh, pH and EDTA extraction data) were correlated against laboratory flotation performance to establish the relationship between oxygen demand and the position of the grade/recovery curve.

Jan 1, 2000

It is possible to closely simulate the product sizing distribution from an industrial rod mill by the correct choice of parameters in laboratory batch milling. For laboratory batch rod milling, changes in per cent critical speed and per cent rod volume cause the product sizing distributions to move in parallel at a constant slope. For ball milling, larger sized media in batch milling grind more coarse material giving a closer simulation to the industrial rod mill product. Changing the feed size distribution by removal of coarse particles or addition of fine particles changes the product sizing distribution, but would not normally be practiced in laboratory testing. These data should be applicable to many instances where laboratory simulation of an industrial product size distribution is required.

Jan 1, 1998

By Savidis G

The characteristics of 'Z' (Back-over run) and 'R' (Reverse) ventilation systems are dis- cussed in relation to their suitability for longwall mining. Experience in European mines has been described as a basis for comparison with Australian conditions. In assessing the merits of each ventilat- ion system, such factors as longwall layout (pillar design, number of headings and gateroad stability), the need for gas drainage and bleed- er systems, as well as the influence of seam dip have been considered relevant. The R system is generally applicable for single and two heading development in seams where gas emission is a less serious problem. In contrast, the lower extraction to development ratio of the Z system (which arises from using three or more heading layouts) is considered more favourable where high gas emission occurs. The Z system provides greater flexibility with respect to the provision of refreshing air at the tailgate end, access of men and materials, installation and retrieval of gas drainage systems and the ability to interchange main- gate and tailgate roadways in cases where roof strata loads are difficult to control, or where cpam in hac an influrnra

Jan 1, 1983

IT is not intended that this paper should be regarded as an account of the geology of the Lyell district. It is merely a synopsis of some of the conclusions recently arrived at in regard to the stratigraphic and structural geology, compiled to act as a guide to those members of the Australasian Institute of Mining and Metallurgy attending the Queenstown meeting who are interested in economic geology. The attempt has been made to present certain salient features, omitting a mass of detail, which, although important in the complete investigation and understanding of the economic geology, yet would be confusing to a group of geologists making a short visit. The location of some of the significant occurrences bearing on the main problems and conclusions are indicated in the text in order to enable members to plan the location and direction of their excursions...

Jan 1, 1927

The past decade hap seen revolutionary advances in com-munications and information-handling techniques which have been stiriulated by "cold war" military requirements and by, current programmes for probing into outer space: The tools used in exploration for petroleum and minerals have been improved significantly as a result of this new space age technology and even greater improvements are on the way.Two areas of technical activity have been particularly fruitful in enhancing the effectiveness of exploration, methods. These are (1) The development of new approaches, based on information theory, for extracting signal from noise more efficiently than before, and (2) The use of high-speed digital computers for storing and processing all kinds of exploration information, not only geophysical but geological as well.In seismic prospecting, use of information theory has led to new techniques such as time-domain filtering, wave-number filtering and correlation methods which have made it possible to obtain usable reflection data from areas which were previously considered NR. Complex playback and other data processing facilities have been developed to apply these approaches.

Jan 1, 1963

By M Miettinen

That microorganisms, both living and dead, and products derived from the organisms, can function as flotation agents and flocculation agents is abundantly clear. They can modify the surfaces of minerals. They can function as flotation collectors and as flotation depressants and activators. In many cases they or their products can function as specific flocculation agents. Problems that must be solved before such microorganisms or products from the organisms can be used in commercial operations include culturing the organisms at a cheap cost and reduction in dosages required for various separations. These tasks are formidable. However, the concept of using such natural materials in place of various chemical reagents that may be toxic is very attractive. An attempt is made to show some of the promise of microorganisms in mineral bioprocessing and to consider the problems that must be overcome before commercial application of the technology is realised.

Jan 1, 2005

By Bloom M. S

Epithermal vein and breccia hosted Au mineralisation at the Kerimenge prospect, in the Wau district, Papua New Guinea, occurs within a block of multiply fractured dacite porphyry of Pliocene age, and is localised on intersecting regional fault structures, marginal to the eroded vent of a Late Pliocene-Pleistocene maar volcano (diatreme).Au mineralisation is primarily controlled by the steeply dipping Kerimenge Fault zone, which hosts a basal zone of silicified breccias,transitional laterally and vertically to networks of fracture controlled veins.Early quartz+pyrite veins, deposited from CO2 rich, NaCl saturated, boiling fluids pre-date the main phase of Au mineralisation. Four stages of Au bearing vein mineralisation have beenrecognised. Quartz+sulphide veins (stage 1) and partially coeval quartz+sulphide+carbonate+ adularia veins (stage 2) occur marginal to silicified breccias, and are associated with quartz+sericite+pyrite wallrock alteration. Similar depositional conditions prevailed for stage 1 and stage 2 mineralisation. Mineralising fluids underwent two stage boiling at temperatures of 145 to 2300 C. Boiling resulted in the loss of approximately 3 wt.% CO to the vapour phase. 2 Fluid salinity was probably I wt.% NaCl or less.

Jan 1, 1990

Facies associations in the Okiduse Volcanics, woodlark island, suggest that two major volcanic centres erupted synchronously during the Middle Miocene. These centres are referred to as the Watou Mountain Eruptive Centre and the Uvarakoi Caldera. The Watou Mountain Eruptive Centre, centred on Boganuse Mountain in the Okiduse Range, was a typical, moderate-sized composite volcano (or stratovolcano). The seq-uence is readily divisible into lava (Boganuse lava unit), breccia (Nikuben breccia unit) and epiclastic (Talpas sandstone unit) dominant facies, typical of composite volcanoes. These facies girdle Boganuse Mountain and they are interpreted to represent vent, cone forming and ring plain associat-ions, respectively. These facies indicate a reconstructed volcano of approximately 1,700m height with a basal diameter of 7km. The presence of limited exposures of intrusive associated with the vent facies (Kuike'beimmicrodiorite) suggests that the volcano is only partially dissected. The Uvarakoi Caldera is a felsic volcanic system contrasting with the mafic Watou Mountain centre.

Jan 1, 1994

By P Malkin, S Thomas, P M. Stone, D Kostyuk

In open pit mining, it is common that the bottleneck to productivity and profit lies in the truck-shovel mining operation, especially as strip ratios and mining intensity have increased with resource depletion and advances in mining equipment capabilities. This paper outlines a study of truck-shovel productivity using a new proprietary discrete event simulation platform for truck-shovel operations called MineDES. The study will specifically address the issue of whether truck queuing at shovels should be considered productive or not, and how mining engineers can determine the optimal truck fleet size for specific operational configurations.The MineDES simulation platform will be described and illustrated, highlighting the features that make it an appropriate tool for conducting the experiments at the heart of this study. The study encompasses a set of experiments, consisting of a number of simple truck-shovel operational scenarios for a benchmark open pit mining operation, which are simulated using MineDES. Each experiment is designed to highlight different factors, which are most important in calculating the ideal truck fleet size and for understanding the marginal productive impact of each additional truck added to the fleet. The scenarios will principally address the issues of how different types and levels of unscheduled equipment downtime and process variation, combined with the traffic delays/congestion arising in more intense mining operations, will affect productivity. The results of the experiments are interpreted using a simple fit-for-purpose cost and revenue model in order to highlight the indicative cost of over- or under-trucked configurations.The study has found that the optimal fleet size that maximises productivity and value will, in the presence of even small process variation, lead to non-zero trucks queuing at shovels on average. As process variations and unscheduled downtime events increase in the truck-shovel system, the required fleet size to optimise productivity and value increases. MineDES provides a convenient platform for quantifying this for real operations.CITATION:Kostyuk, D, Thomas, S, Malkin, P and Stone, P M, 2014. Is truck queuing productive?, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 267–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By E Kunz

Decreasing the gas content in the worked seam by degassing before the start of winning has proven its worth in some areas of German hard coal mines. On the one hand, it removes the risk of gas/coal outbursts and on the other hand it reduces the gas inflow into the longwall. The underground experiences of the last 30 years have led to a æhit listÆ of coal seams with respect to their suitability to predegassing. Trials in the DMT laboratory and also results gained in the deposit show that the suitability of a seam for predegassing depends on its rank. In seams with volatile matter of 20 - 30 per cent, high efficiency ratings are achieved as a rule, with lower ratings both in seams with lower and with higher content of volatile matter.If the rock pressure is unusually high, the efficiency rating of the predegassing is lower, even in seams which would normally be suitable for this process. Under unfavourable conditions, for example below or above residual pillars, in-seam boreholes cannot be drilled successfully and the method is not practical. But if the worked seam was already stress relieved, the predegassing has an optimal efficiency. Latest investigations show that the distance between the in-seam boreholes can be extended. But in that case, the time necessary to reach the same reduction of the gas content increases considerably.

Jan 1, 2005

By Beer G

The recent re-emergence of an Integral Pressure Stripping system which operates with both cell and column in closed circuit at elevated temperature and pressure, requires no cyanide in the eluate solution and has greatly reduced carbon reactivation requirements in seen as a progressive step in this area. Several of these re-configured IPS systems have been placed in service in Australia and overseas in the last three years, with the first of the new generation units constructed and commissioned by Como Engineers Pty. Ltd. at Mt. Fisher in the East Murchison of W.A. in September 1987. This plant was relocated to a new ore body at Darlot W.A. in February 1989. Use is made of a data base of raw plant performance figures from both Mr. Fisher and Darlot and its performance compared with other operating plants. Initial commissioning difficulties of the Mt. Fisher prototype and dis- cussed together with the modifications and operational procedures required to overcome these problems. Stripping times of less than 6 hours at 145 degrees have been achieved with barren carbon values less than l O ppm from loaded carbon values above 3000 ppm and with cell pass efficiencies reaching 90 per cent.

Jan 1, 1991

By S Furman, M Caccetta, A Hacket, B McDonald, M A. Wells, D Lau

In 2004, the Western Australian Department of Industry and ResourcesÆ Burrup Rock Art Management Committee commissioned a number of independent scientific studies to evaluate the condition of rock art in the Burrup Peninsula near Karratha (Western Australia). These studies are evaluating the physico-chemical aspects of the effect of environmental modification on the visible appearance of the rock art. Because of the cultural significance of the sites, the research approach has been to employ non-destructive testing strategies and work in the field has progressed with respect for the importance of the area. This paper only reports the spectral mineralogy monitoring at each of the sites to evaluate whether changes in mineralogy are observed on rock surfaces. Reflectance spectroscopy is a non-destructive, in situ materials characterisation technique that provides information about the mineralogy. The minerals detected include haematite, kaolinite, chlorite, goethite, gibbsite and manganese oxides. Current results indicate that the surface mineralogy of the rock art has not changed in the last four years.

Jan 1, 2008