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By Fernando N, Guang LX

Brown coal in Victoria in spite of its substantial reserves is not utilized greatly because of its high moisture content(-65% w/w). Transportation and handling costs of raw brown coal, on an available energy basis are so expensive that 93% of production is burnt for electricity generation on or adjacent to the coal deposit in Victoria. With direct firing of moist brown coal in power stations, approximately 20% of the gross calorific value of the fuse is used to evaporate the water contained in the coal. This energy is lost as vapour with the flue gas which is vented to the atmosphere. Also there is a 25% increase in flue gas volume and the size and cost of most of the units through which it passes must be appropriately larger. Since there are large quantities of water present the flame temperature is significantly reduced. For zero excess air and no air pre-heating the theoretical flame temperatures are: 609'o wow moisture 1450¦C 40% ª ª ª 1790¦C ZOO ª ª ª 1990¦C As a result of this there is a reduction in radiant heat transfer leading to a requirement for a two fold increase in radiant tube area. A boiler of much greater size and cost is thus required to house the additional tubes. Figure 1 illustrates the relative sizes of a boiler fired with 60% moisture brown coal with a boiler or similar output fed with a British bituminous coal, 14% moisture.

Jan 1, 1989

By Y Ren

The algorithms employed by the commercial tools are either heuristic algorithm or iterative optimisation of a subsystem. This often results in a suboptimal schedule. In this paper, the author presents a new scheduling algorithm that incorporates with a novel stockpile configuration system, an improved algorithm on multiple processes and a mixed-integer linear programming (MILP) global optimisation model. It can simultaneously optimise stockpiles, blending, multiple processes as well as multiple mines. In addition, it allows the user to interact with the solution to adjust the solution to be practical and desirable.CITATION:Ren, Y, 2013. A simultaneous optimisation tool for open pit mine scheduling, in Proceedings World Gold 2013 , pp 427-432 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By M Grossi, G Baiden

This paper describes a new mine backfill method based on a newly invented binder with several years of test results from laboratory and onsite applications. The new binder has several advantages over traditional Portland and slag cement binders. One tonne of the new binder can replace two to three tonne of Portland cement when used to consolidate backfill and can result in the same compressive strength within seven days. When comparing backfill slurries of the same pulp density, the new binder attains more volume of in-place backfill mass than Portland cement because of the high crystallisation of water, resulting in tightly filled stopes. The crystallisation of the water provides for less or no dewatering in the backfill stope and easier transportation of the backfill slurry. Pastefill performance can be achieved by using pulp densities typical of a hydraulic backfill and the new binder, all the while transporting with the same ease of hydraulic fill.

Jan 1, 1998

Laboratory experiments have been used tostudy a wide range of convective processes which are significant for the formation of rocks and the ores that form in them. Metal-rich solutions flowing through the sea floor produce 'black smoker' chimneys; both the size and structure of a solid chimney and the height to which the plume of effluent rises above it can be predicted using model experiments. Analogues of processes in solidifying magmas can also be studied using crystallizing aqueous solutions. The release of lighter or denser residual fluid as crystallization proceeds, and the resulting compositional convection, have a vital influence on the differentiation of initially homogeneous magma and on the evolution of stratified magma chambers. Mixing during the replenishment of magma chambers, and its dependence on the rate of filling and on the fluid properties, have also been studied on the laboratory scale. Experiments carried out in different geometries have been applied here to the formation of platinum and chromite ores and komatiite lavas. Larger-scale mantle convection, in particular the motion of subducting plates and plumes rising from the core-mantle boundary, also determine the tectonic settings in which ore bodies form. These phenomena too can be usefully investigated in laboratory experiments using very viscous fluids.

Jan 1, 1990

By Maxwell HW

Pacific Coal Pty Limited (a wholly owned subsidiary of CRA Limited) managed the interests of six members of a joint venture formed to mine and export eight million tonnes of export quality steaming coal from a mine developed at Blair Athol in the Bowen Basin of the Central Queensland coal fields. The mine is now operated by Blair Athol Coal Pty Ltd. Crooks Michell Peacock Stewart Pty Limited (CMPS) was awarded a project management and engineering contract for the total mine portion. Following a feasibility study, CMPS carried out an Optimisation Study which produced changes to the design of the project, thus resulting in the project budget being reduced by some A$13 million. In spite of a number of late additions to the scope of work, the project was completed at a final cost of A$148 million, many millions below the reduced project budget. The project was also completed several months ahead of schedule. Total services were provided to take the project from feasibility stage through to the establishment of an operational facility and included project management, planning and control, accounting and financial control, as well as the organisation of engineering, procurement, construction, industrial plant commissioning, and technical training matters.

Jan 1, 1986

By Alvarez A. R, Garcia H. l

A fuzzy expert system, DIME, has been developed, under Matlab v 5.1. to assess the coal and gas outburst risk in underground mining. Expert systems and fuzzy logic are powerful tools to manage information represented by linguistic statements,

Jan 1, 1998

Buoyant levels of world economic growth and recovery in intensity of metals usage suggest that demand for minerals will remain relatively strong into the 1990's. Supply constraints, low stock to use ratios, financial and political factors imply lower elasticities of supply for minerals in the future. The outlook for minerals and metals prices from a pro-ducers viewpoint is, accordingly, promising.The recent recovery in world minerals prices, following strong growth in the world economy over the last few years, makes it appropriate to consider the structural forces at work in the formation of world demand and supply of minerals. This paper will review past trends and consider some of the main economic issues facing the mining industry in the 1990's.

Jan 1, 1990

Blasting, particularly bench blasting, uses finite length cylinders of explosive close to two free faces. The rock to be blasted is usually intersected by a complex 3-D system of joints. To fully simulate a blast, a 3-D dynamic model is required. It is shown that the static stress distribution around a long cylinder can be reproduced by superposing the static stress distribution of a suitable chain of spheres. Thus, the dynamic results for individual spheres given by Favreau (1969) can now be substituted for the static results to give a dynamic model of the stress distribution around a long cylinder. Comparison of measured and computed waveforms show that the measured waveforms are much more attenuated and dispersed than expected. The consequences for explosive evaluation and design are Discussed.

Jan 1, 1990

By Blair J. R, Barrett J. R

In many underground mining applications where-dry fill is used, only a token acknowl- edgement of the fill properties is given. It is the aim of this paper to induce mining engineers to consider dry fill as an engineer- ing material rather than a mass to place in unwanted voids. Dry fill is generally cheap, inert and readily available, but it can still contribute to mining performance. In particular, the choice of the dry fill becomes more critical as stope sizes increase, controlled choked draws are used or pillar recovery introduced. Selection must be initiated from an evaluation of the role of the fill in the mining operation. In most cases the fill must be chosen before quarrying begins and an investigation must be made of available sources and appropriate quarrying methods. Some of the properties of fill are described together with evaluation techniques. A com- parison of placement conditions is limited by the complexities of material flow and degrada- tion: However, field and model tests can aid interpretation in these cases. Examples are given of aspects of dry fill selection and their incorporation in mining design.

Jan 1, 1973

By Shugen T

Due to the increase of passenger traffic, a new station is proposed which is about 6.8km from south station. An underground connection line is under feasibility study for connecting these two stations in order to avoid the in- terference with surface traffic. In this paper the traffic condi- tion and the geological formation along the planned route will be described and analysed. Different methods of con struction have been proposed and dis- cussed such as shield method, slurry wall method etc. In this paper compari- sons are made among these methods and advantages and disadvantages given. The authors proposal to construct this connection line by NATM raise wide

Jan 1, 1987

By Felice J. J

The assessment of the face velocity of blasts is important in the analysis and subsequent improvement of blast performance. POWERWAVE RADAR is a new tool which will make the collection of this data easier for blast researchers. The data collection technique ensures that a large amount of face velocity data is collected from a blast, and describes the velocity characteristics of the face at a new level of detail. This results in a greater understanding of the effect of drilling and blasting parameters on blast performance. Several case studies are presented which illustrate the collection technique, the type of data generated and how the data is used.

Jan 1, 1992

By G Harbort, D Clarke, D Morgan, C Sola

Northparkes Mines commenced production in 1994 and the mine has significant reserves to allow operation into the future. There are a number of potential future concentrator feed sources with variable sulfide mineralogy and grades.In February 2012 a comprehensive flotation survey was conducted to allow mass balancing and evaluate the operation of the flotation circuit. A rudimentary, copper element only, unsized flotation simulator was developed to evaluate high level potential for optimisation and improvement. In 2013 this flotation model was expanded to produce a mineral based, floatability component model to estimate the effect of future concentrator feed source on metallurgical performance. This revised model allows various circuit configurations to be simulated to provide a high level blueprint for the long-term planning to maximise performance.This paper provides a review of the process followed to develop the model, including an analysis into the mineral floatability component model and its calibration against plant operations. The effect of varying feed mineralogy and feed quality on future performance has allowed an internal review of potential circuit changes needed to accommodate the changing future feed.CITATION:Clarke, D, Harbort, G, Morgan, D and Sola, C, 2014. Northparkes Mines – flotation and planning for the future, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 203–208 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

The equity market is now very much within a global village environ- ment, with various exchanges acting as agencies for the big casino. In this predicament, mining companies, who provide the most extensive, but relevant risk assessment information, will be best placed for favoured treatment by potential international investors: But what risk assessment information in summary form can be provided to support a resource/reserve statement? Even more importantly, does "objective" data exist, whose trends will support a resource/reserve state- ment? A prime need of the informed mining investor is to determine whether or not the resource/reserve statement is believable? But more importantly will it be realised? While the implications within the text of the majority of reports on resource/reserves suggests that the estimates are conservative, the record indicates that very few estimates are. In fact, to date, reports claiming to be conservative in respect of the overall grade estimate at a specfic cutoff have not reflected the realised grade at the stated cutoff; it has been more common for the realised grade to be lower than implied by the resource/reserve statement. Further, it is not uncommon for penalty elements to be understated and these components are rarely incorporated within resource/reserve statements.

Jan 1, 1988

The Split Rock low grade copper prospect was discovered in 1969 by Cyprus Mines Corporation using stream geochemistry. Cyprus "Imes carried out geochemical and geophysical investigations, geological mapping, and percussion and diamond drilling, and concluded that the grade of mineralisation was too low (0.1% copper) to be of interest. In the present study, the geology was remapped and very substantial differences from the previous observations are recorded. (lineraliced acid dykes in a 1 000 foot hole drilled by Cyprus Mines had a total inter- section of almost 300 feet with an average crade of 0.4% copper. Surrounding drill holes at distances of 500 feet did not intersect +hese dykes. This group of drill holes occupies a small part of an area about 2 km by 1 km which was affected by intense quartz sericite pyrite alteration along many fractures with an associated soil copper anomaly. It may be that the quartz sericite alteraiion with feeble copper mineralisation represents hydrothermal alteration emanating `rom a mineralised intrusion of which the dykes mentioned above are off shoots.

Jan 1, 1978

By J H. Baker, P G. Beadle, J P. O&apos, Brien

In 1974 a preliminary study of the refractories industry in theRepublic of Indonesia was completed by Crown Lynn Consultants, a subsidiary of Cerarnco Ltd., on behalf of the Indonesian and New Zealand Governments. As a result of recommendations arising from that study the two Governments commissioned, in 1976, as a Bilateral Assistance project, an investigation into the potential of the refractories industry in Indonesia. Ceramco Ltd., was retained to carry out the study on behalf of the New Zealand Government. The Directorate-General of Chemical Industries, Directorate of Silicate Industries administered the project on behalf of the Indonesian Government. Indonesian counterparts to the New Zealand study team were provided by the Directorate of Silicate Industries.

Jan 1, 1978

Traditionally, surface coal mines in the Western United States have been limited by economics to depths between 150 to 200 feet. Utah International Inc., however, is now planning to strip coal its San Juan Mine in Northwestern New Mexico to depths ranging up to 400 feet while uncovering 20 feet of steam coal. This method is cost-competitive with nearby shallower coal deposits and underground mining of the same property. How trucks and shovels can pre-strip for a dragline, along with results of the planning process, comparison with alternate systems, capital requirements, operating costs and comparisons with other coal sources are all detailed. Also discussed are the major problems anticipated, how they might be corrected, and potential improvements to the concept. Introduction The San Juan Deep Stripping Project will be situated at Utah International's San Jean Mine. The mine is in the Four Corners region, so-called because four states enjoy a common border point about 30 miles to the northwest.(see Figure 1). The area is a semi-arid plateau region with an average elevation of 5,200 feet, receiving an average of 6 inches of precipitation annually

Jan 1, 1981

By Mathew P. J

The CSIRO Division of Mineral and Process Engineering in Melbourne has been developing on-stream analysis sensors based on neutron and gamma radiation for better control of quality and process operations. This has resulted in the development of Ironscan, an on-stream analyser that measures the iron content of both lump and fine iron ore on conveyor belts. It can be mounted under existing conveyors with minimal modifications to the conveyor structure and can cope with steel cables in the belt. An interface gauge and an on-stream coal ash analyser have also been developed, both based on measurement of natural radioactivity. The interface gauge monitors the interface between liquor and mud in thickeners and washers, provided the natural radioactivity of the mud is sufficiently high to detect it above background. The natural-gamma ash gauge is a valuable addition to the Coalscan range of ash gauges. It is applicable to heavily laden coal conveyors or bins where the coal bed thickness exceeds 30 cm, and also to lightly laden conveyors, provided the coal is profiled on the conveyor.

Jan 1, 1991

Currently there is considerable interest in the production of DRI in Western Australia to take advantage of intense interest from the Asian market. Most DRI is produced using gas-based processes and is used as a feedstock in electric arc steel furnaces, otherwise known as mini-mills. This paper critically examines the technical and economic issues of various gas-based DR processes available today and recommends the most effective and attractive processes suitable for Western Australian iron ores.

Jan 1, 1996

By R Castroviejo, F Segundo, C Brea, J-C Catalina, H-J Bernhardt

Optical microscopy is a basic but still indispensable tool for examining mineral parageneses in ores. The design and concepts behind the reflected light ore microscope have obviously not been subject to spectacular technical evolutions in the last decades. However, digital imaging capabilities have opened new and stimulating perspectives for automated mineral identification. Recent works in developing multispectral image analysis (Pirard, 2004) have demonstrated its superior potential with respect to conventional colour imaging, but at the same time reconciliation with spectroscopic databases such as the Quantitative Data File III (Criddle and Stanley, 1993) still needs a more in-depth investigation as well as the possibility to extend both imaging and spectroscopy into the near infrared domain. In this paper, the authors present results gained from multispectral imaging in the range between 400 and 1000 nm together with spectrophotometric data from the QDFIII database, with an emphasis on minerals that cannot be easily distinguished in the visible spectrum.

Jan 1, 2008

By Ruston R

When coal mining first commenced in Australia, the principle objective was low cost production with development directed toward recovery of 'easy' coal. Future expans- ion of these early mines into major under- ground operations was neither envisaged nor planned. As the demand for coal grew, these mines were expanded to increase output. however, the absence of initial ventilation planning brought about ad hoc systems wh;ch required continual repair and upgrading. These systems proved satisfactory in the short term because the majority of undergrouni coal mining operations were carried out at relatively shallow depths where gas emission rates were low. By comparison, coal is now being won at depths exceeding 500 metres with a corresponding increase in gas flow from the working seams and adjacent strata. The following paper addresses, firstly, the planning and institution of a ventilation system in a mine where previous inefficiencies were many, and secondly, the value of pre- planning a mine ventilation system in the early stages of mine development, and the need to continually review and upgrade the plan to account for unforeseen ^hanges.

Jan 1, 1983