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By B J. Wight, R Mackay, S Kim

Improving the understanding of the processes governing ground movements in and around brown coal open cuts is of significant interest for both operating stability and rehabilitation. Brown coal, lignite, is a low-rank coal that is best described as a soft rock, with geotechnical characteristics that derive from its organic origin. It is well-known that low-rank coals exhibit creep behaviour; however, little has been reported on the impacts of chemical processes on brown coal creep behaviour even though organic substances are susceptible to chemical alterations and mining processes will contribute to changes to the geochemical environment; around most mines, groundwater flow patterns are altered leading to enhanced surface water infiltration. Here we study the deformation behaviour of brown coal in response to ion exchange reaction. Our experimental results show that for different ion exchange conditions different characteristics of secondary compression are observed. With the addition of Ca2+, the ratio between coefficients of secondary and primary compression (Ca /Cc) initially decreased, presenting a minimum value at the concentration of 0.005?M, then increased significantly. This implies the importance of ion exchange process for the long-term deformation of brown coal. On the other hand, increasing Na+ concentration did not affect Ca /Cc values significantly over all tested concentrations. The suppression of diffuse double layer was still observed for Na+-treated samples as increasing Na+ concentration decreases Ca values. From a practical perspective, this study did not consider the tertiary creep behaviour and eventual creep failure.CITATION:Kim, S, Mackay, R and Wight, B J, 2014. Creep due to chemical alteration of rocks – a case study in brown coal, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 61–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By D Millette, F Gay

Surface tailings are finely ground waste materials produced in all mines after the mineral or metal has been removed from the metallurgical process. Current methods for disposal of tailings involve constructing dams, dumping into existing waterways, and depositing as backfill underground. Each method has its drawbacks in terms of cost, level of complexity, safety and environmental concerns. Backfilling is the process whereby waste material (generally metallurgical tailings, prepared aggregates or a combination) is placed from the surface back underground into open mine workings via conveyor belts, hydraulic or pneumatic pipes or gravity. In the backfill process common difficulties are expensive placement costs, equipment wear and the ability to meet early and long-term strength requirements. Traditional tailings transportation in pipes involves the use of water as the transport medium. Foam technology involves the introduction of micro-air bubbles that replace the water as the main transport medium. This air can be removed after placement if necessary, by the addition of a defoaming agent. This could produce an under-saturated stable cake. Foam technology has the potential to revolutionise surface tailings disposal and backfilling by providing a less expensive and environmentally safe alternative to those just described.

Jan 1, 2000

By Minglin W, Zhixing L

The laws of detonation wave velocity variation in propagation process along the charge under channel influence are investigated widely in this paper. The result is obtained by blasting experiments. Bore hole is simulated by plastic tube or steel pipe (with outer diameter 45 nun, inner diameter 40 or 41 mm). Blasting experiment is carried out with a cylindrical charge of 32 mm diameter. The author analyses the characteristics of energy distribution along the charge under above-mentioned conditions. Reasonable initiating position and initiating direction are also analysed. A double-direction initiating method which consists of several initiating charges is put forward. The blasting effect of this initiating method when used in underground mining is stated out.

Jan 1, 1990

By Spencer GA, Saul SJ

The flight line spacing in low level aeromagnetic surveys is the principal factor governing both the cost and the amount of geological detail which can be extracted from the data. The rate at which geological resolution diminishes with wider line spacing is illustrated by progressive subsampling of a 200 m spaced data set from the Charters Towers region in Queensland.The usefulness of high frequency type filters in enhancing shallow structural features is seen to be limited to the 200 m data.It is concluded that each data set is suited to a particular scale and style of geological investigation with only the 200 m data having sufficient detail to identify the subtle structural patterns which are crucial to mineral exploration.

Jan 1, 1976

By J Palaci, M MelTndez, F Parra, I Rojas

At the Huasco Pellet Plant of Compa±fa de Aceros del Pacffico, Chile, the production of iron concentrate suitable for pellet feed from a low-grade iron ore was technically evaluated. In this study, three treating schemes including comminution, magnetic concentration and flotation in pneumatic cells were tested. The best results were obtained at the laboratory scale by flotation technique using Lilaflot D 817 M as the collector without using any depressant. The operational parameters were determined including pneumatic flotation, and three circuits, two including magnetic pre-concentration, with the low-grade iron ore. The best results were obtained by size reduction at 80 per cent under 325 Tyler mesh, three steps of magnetic concentration and three steps of flotation in pneumatic cells. The magnetic concentrate contained 63.02 per cent of iron and 6.6 per cent of silica, and after the pneumatic flotation the iron content increased up to 70.18 per cent and silica decreases to 1.07 per cent with 78.78 per cent of iron recovery at a weight recovery of 31.89 per cent. Therefore, it is possible to use low-grade iron ore to produce pellet feed from magnetic concentrates by using reverse iron flotation in pneumatic cells.

Jan 1, 2005

By Forsythe DJ, Sun S-S Andrew AS

Paragenetic, fluid inclusion, stable isotope, and 87Sr/86Sr and 143Nd/144Nd isotope studies of the Mt Carbine tungsten deposit in North Queensland provide information on the sources of the mineralising components and record the history of fluid-rock interaction during the hydrothermal process. The ore minerals , wolframite and scheelite , are contained in quartz veins which post-date the major deformations in the Siluro-Devonian Hodgkinson Formation . Mineralisation was immediately preceded by the emplacement of the Mossman Batholith (280 ¦ 7 Ma). Two major stages of mineralisation are present and separated by a brittle fracturing episode . The stable isotope and Sr and Nd isotope data suggest that the ore fluids during stage I and most of stage II mineralisation were a mixture of magmatic water and non-magmatic water (connate or metamorphic) which had experienced a long residence time and had extensively exchanged with the sediments at high temperature. Subsequent mineralisation events were dominated by fluids of meteoric derivation with a short residence time. The data imply that other solutes, such as W, were probably derived in minor part from local country rock sources with the major contribution coming from a magmatic source related to the granite batholith.

Jan 1, 1987

The paper deals with the taking of soundings in connection with coal mining operations under part of the Pacific Ocean adjoining John Darling Colliery.INTRODUCTIONIn the early days of mining in the Newcastle District there did not appear to be any definite law specifying the limits to which mine workings, other than certain borings, could extend under tidal waters.As time went on, a figure of 120 ft. was fixed as the minimum thickness of strata between the roof of the seam and the sea bottom; beyond this mining operations are disallowed. The laws relating to working coal under tidal waters are as follow:-The minimum width of pillars to be left shall be eight (8) yards and the maximum width of bords or other excavations shall be six (6) yards, but the lessee may at his discretion increase the minimum width of the pillars or decrease the maximum width of the bordsor other excavations so as to increase the general safety.The eight (8) yard pillars shall be left unwrought.In on-road of every pair of Winning-off or leading headings, a bore shall be kept going ten (10) feet in advance for the purpose of foretelling the presence of any fissure, wash-out, open joint, fault, dyke, or otherwise, and all winning-off headings shall be driven atleast one hundred (100) yards in advance of the working bords.The most accurate and trustworthy information shall be obtained by the lessee not only' of the depth and character of the ocean bed, river, lake, or estuary deposit, but also of the strata overlying the coal seam.When working under the ocean, strata shall be bored through and proved a minimum thickness of thirty (30) feet at the face of the leading headings or levels immediately such headings or levels are under the ocean, and...

Jan 1, 1947

We can look at the water treatment and management strategies at some recently commissioned mines and minerals processing sites to see the likely future of water in mining. The future of water in mining will be based on a holistic approach to understanding the site water balance, appropriate treatment, reuse where possible, and environmentally managed discharge where required. This paper describes advanced and innovative water treatment and reuse processes as used by mines and mineral processing operations from around the world. Underground mining can often require dewatering to prevent groundwater seeping into and flooding the mine workings. Mining and processing often accumulates wastewaters in a tailings dam. The mine water can contain contaminants such as dissolved salts, iron, arsenic, manganese, heavy metals and acidic and odorous sulfates. On-site reuse, environmental discharge requirements, as well as community needs for water, drive mine operators to consider the most appropriate water treatment process. Mining water treatment for the future is described using case studies of innovative processes. The case studies include treatment of mine dewatering water for beneficial application from Australian mines, Ballarat Goldfields and Bendigo mining, treatment of produced water from oil and gas projects, and treatment for arsenic removal of tailings water from mining and processing at Goldcorp mines in Canada. Advanced and innovative processes including membrane filtration, reverse osmosis at extreme conditions, advanced biological treatment and water management are all part of these case studies. This paper uses real case studies of advanced and innovative mine water treatment processes to explain and examine the technology and the reasons for designing specific processes. The focus is on innovative processes that may be more widely used in future mining û where the water is used for sustainable environmental discharge or treatment to a quality that can be beneficially used by the mine or the local community.

Jan 1, 2008

By Johnstone RD, Rattenbury MS

RACE Quartz-calcite veins containing Au, As, W, Cu, Pb, Zn and Fe cross-cut Alpine Fault- related structures in the Alpine Schist of South Island, New Zealand. These veins, and some other related veins have been deposited by metamorphic fluids at 250¦C to >320¦C at pressures of a few hundred bars. The fluids were very variable in composition, with 0 to 50 mole % CO2 and 2 to 18 wt. % NaCl equivalent. Penetration of hot metamorphic fluids to shallow levels in the crust was facilitated by rapid uplift of hot rocks at a compressive plate margin. Fluid immiscibility at shallow levels caused concentration of salts and metals into the aqueous phase. Gold precipitation was caused by reduction by pelitic country rock and/nr dluILion by other aqueous fluids.

Jan 1, 1987

By Meloy TP

Several important, fundamental aspects of the grinding behaviour of mineral systems are addressed. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations was used to solve the steady-state and dynamic population balance model (PBM) grinding equations to obtain the mill matrices and grinding selection and breakage rate functions, respectively. The fact that the PBM model equation Inverse Problem is degenerate or underspecified is demonstrated. Multiple solutions to the same PBM equations are provided. It is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the Arbiter-Bhrany normalisation assumption. The severity of the non-uniqueness problem for steady state grinding is demonstrated in several examples using typical feed distributions and mill matrices. In addition, it is also demonstrated that when higher than single powers are used in steady-state mill matrix expressions during simulation or calculation (or iterative procedures are used during numerical simulation) and four or more size intervals are used considerable amount of error is propagated throughout any calculation. Each solution to a PBM, while giving the same prediction during a single mill pass, gives different solutions or predictions for mill composition upon subsequent passes. In addition, it is shown that there is a problem with building up a grinding mill knowledge base with PBMs. A similar analysis was done for the dynamic or kinetic PBM equations. The fact that the dynamic PBM Problem is degenerate or underspecified is also demonstrated. Multiple solutions to the same dynamic PBM equations are provided. Again, it is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the normalisation assumption. Each solution to a dynamic PBM, while giving the same prediction for a given grinding time interval, gives different solutions or predictions for mill composition for other grinding times. Actual experimental grinding data was assessed to determine the functionality of mill selection and breakage functions. The functionalities obtained through constraints were compared with those obtained with the normalisation assumption of Arbiter-Bhrany which relates breakage functions to particle size distribution. The capability of the population balance model to predict grinding behavior over time in various mineral grinding systems was assessed. The required functionality of selection and breakage functions for effective prediction of grinding behavior in mineral systems is discussed.

Jan 1, 1993

Early efforts to control the dust necessarily produced during dry crushing operations, took the form of venturis at loading chutes and other places where dust was most evident. These venturis discharged to the atmosphere and for obvious reasons were not very satisfactory.Attempts to collect the dust drawn off by the venturis, using dry cyclones, were not successful, the cyclones catching only the coarser particles. Further, no satisfactory method of continuously discharging the dust catchment was evolved. Water sprays were also used, and will be referred to later.In 1940, a single discharge fan of 3,000-4,000 cu. ft. per minute capacity, was installed to draw the dust-laden air from the Symons crushers and ·screening sections with their attendant conveyors. Suction was through two 15 in. ducts which branched off into 10 off-takes situated over the conveyers at points of discharge from crushers and screens.A dry cyclone was installed in front of the fan, which exhausted into a bag-house.The cyclone suffered from the defects of the smaller units mentioned earlier. When the collected dust reached a certain level in the cone, no more collection would take place until the cone was emptied. This objectionable feature was overcome by introducing a jet of water ahead of the cyclone. The water and dust collected overflowed a weir and were pumped to the mill.

Jan 1, 1948

By Reid A. F

Since early 1971 Western Titanium N.L. has been operating an ilmenite upgrading plant on a commercial basis at Capel, Western Australia. In their process ilmenite is pre- oxidized, then reduced in a rotary kiln to a mixture of metallic iron and titanium oxides. The iron is leached out by accelerated rusting in aerated water, leaving a product with titanium content, expressed as Ti02, of about 92%. Samples from different stages of the up- grading process, representing operations over the last two years, have been studied in detail by X-ray diffraction methods, and the sequences of phases and reactions occurring have been determined. Quantitative X-ray studies showed the ilmenite feed materials to consist of a mixture of ilmenite and pseudo- rutile. Pre-oxidation of the ilmenite at =1000¦C leads to the formation of rutile plus a Fe2TiO5-FeTi205-Mn2TiO5 solid solution. The final reduction product consisted of a mixture of metallic iron, reduced rutile and a FeTi05-MnTi205-Ti305 solid solution. The relative amounts of these reduction products were very sensitive to the initial concentra- tions of the minor constituents manganese and magnesium. The effects of variation of ilmenite feed rate, reducing atmosphere,- reduction temperature and controlled addition of magnesium were also studied.

Jan 1, 1973

By P D. Munro

The spatial distribution of ore with similar processing properties or domains within an orebody may be identified early in the assessment of an orebody to provide a sound basis for later development of the orebody. The assignment of domains in the primary sulfide portion of an orebody is often more difficult than recognition of the oxidised, supergene and related domains usually located towards the top of the mineralised volume. This paper will discuss some approaches to assigning domains within the primary sulfide portion of an orebody. The processing properties of each mining block will be known if the contained domain(s) and their proportions are known. The use of both physical and chemical ore properties to assign the domains is discussed. The domains based on similar processing properties do not necessarily coincide with geological zones assigned by geoscientists. As part of assessing the physical properties of ore, the modal analysis of the ore with respect to the valuable sulfide minerals and the sulfide and non sulfide gangue minerals has to be known, along with the traditionally used elemental assays for valuable and penalty elements. Two scales for determining other physical ore properties will be considered: the mesoscopic scale (examined by human eye) and the microscopic scale (examined via a microscope under high magnification). The strengths and weaknesses of the data obtained at the two scales are discussed in the paper. Broadly, data collected at the mesoscopic scale are much less expensive but the types of data available are more limited. Methods for evaluation of chemical ore properties are also discussed. After establishing a basis for establishing the spatial distribution of domains, variability testing is required to verify the integrity of the designated domains. In contrast, each block of ore in some orebodies has been assessed principally via the results of a laboratory separation on a number of drill core samples or composites from throughout the block, with minimal or no attention to the concept of domains.

Jan 1, 2008

By Bilodeau M. L

The paper describes a model which has been developed to assess the economic charac- teristics of base metal investment in Canada and the effects of past, present and possible future sharing systems, particularly mining taxation systems, thereon. The model is illustrated by applying the 1976 Canadian tax system to the economic characteristics of base metal discoveries made in Canada during the 1951-1974 period.

Jan 1, 1977

By R Yong, A McEwan, D G. Miljak, D Milinkovic, A Curtain, P J. Coghill, R Stefulj, B Lovric, G Roberts

The CSIRO has pioneered the development and use of certain classes of magnetic resonance (MR) for mining applications. The MR technique is a radio frequency-based spectroscopy that provides highly quantitative measurement of selected ore minerals. MR has many inherent advantages for bulk sensing in mining applications, including deep sensing penetration into most bulk ores with the use of non-contact sensors that are robust and tolerant of demanding mine conditions. The highly discriminating nature of the technique also provides the very desirable attribute of robust and simple calibration, that can often be performed prior to sensor installation. Rapid sensing (within seconds) at very low grade (few hundred ppm Cu) has been demonstrated, as well as sensing at high tonnage rate. Besides sorting applications, MR may also be applied to preconcentration applications involving very large volume sensing including: (i) haul truck sensing using portal arrangements, where truck destination assignment may be dynamically determined based on the truck grade, (ii) in-pit gantries used for loading trucks that may similarly be equipped with sensors for truck assignment and (iii) deep mine bench sensing, recently progressed through a CRC ORE project, where local bench grade is determined at the few-metre lateral scale and at depth prior to blasting, to aid selective blasting and ore extraction. MR sensor prototypes have been developed for each of these applications and have been tested in laboratory or limited field conditions. To inform the value proposition for truck or bench sensing, initial analysis of truck assignment improvement based on an analysis of in-situ mine bench grade has been performed for a porphyry style deposit. The prototype sensors, preliminary results and future technology development and objectives will be described.

Nov 10, 2020

By D Phillips

One of great challenges is to determine the exact timing of gold mineralisation in centralVictoria due to suitable materials and/or geochronological techniques. Here we report new mica and pyrite 40Ar/39Ar age data by laser probe and step-heating furnace analyses, and discuss problems in data collection and interpretation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By M Pratt

For up to 75 years large scale coal mining has been carried out within the Latrobe Valley region of Victoria. Withdrawal of groundwater from Tertiary aged sediments within the Latrobe Valley is essential to allow coal mining to proceed to depth. Water within the overburden layers, coal seams and interseams must be drained to avoid flooding during the mining process. The pressure in deeper aquifers must also be lowered to avoid floor heave, batter instability, and to maintain safe operating conditions as the mines develop in size and depth. The cost-effective management of the groundwater systems at and adjacent to the mining operations in the Latrobe Valley is essential to enable the efficient utilisation of the coal resource whilst minimising the environmental impact of this major industry in rural Victoria. Large-scale depressurisation and dewatering programs within the Latrobe Valley mines are managed through the use of detailed groundwater management plans. These incorporate:an extensive monitoring network which extends up to 60 kilometres from the mines; detailed mine scale and regional groundwater and hydrogeological models; and established operational procedures aimed at minimising capital and operational costs associated with the mine groundwater systems. Groundwater extraction system optimisation programs have been introduced into two of the mines with the aim of reducing extraction rates, improved risk management, and reducing operational costs by approximately whilst not compromising mine safety. This paper reviews the aquifer depressurisation and mine dewatering operations of the Latrobe Valley mines and illustrates the techniques utilised to ensure that high artesian pressures do not adversely impact on the mining operations.

Jan 1, 2003

The large El Cerrejon coal open pit in north east Columbia has been developed over the last decade in a remote, entirely new mining area with hitherto unskilled inhabitants. Now over 200 pieces of heavy equipment operate with high reliability and availability due to successful theoretical training and skill improvement programs tuned to the specific reliability needs of the worksite and environment. The process of continuous improvement adopted promises further competitive advantages of the project.

Jan 1, 1991

By N C. White, L Danyushevsky, D R. Cooke

Comb-layered textures preserve the cyclic accumulation and release of volatiles inside magmas that are temporally associated with large Cu-Au-Mo-rich porphyry ore deposits. Fluid inclusions in these textures sample pristine magmatic fluid. Microanalysis of this fluid helps constrain the physical models that operate at melt-fluid interface and in the broader magma system responsible for ore deposit formation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Eaton R. A

The design of most underground mining machines shows little evidence of regard for ergonomic principles and operator comfort. Likewise, efficiency and ease of operation often appear to have been given little consideration in machines where ruggedness and simplicity have tended to dictate the configuration. Improvements in productivity are amongst the benefits to be gained by a different approach to machine design. The paper describes the philosophy and features of a test bed Load-Haul-Dump Vehicle undergoing trials at Mount Isa Mines. This machine is the outcome of a Research and Development Programme conducted by the Department of Mechanical Engineering at the University of Queensland and Mount Isa Mines Limited. The diesel powered test bed features an enclosed, air conditioned cabin, with a suspended operator's control station and electrically operated controls. An electronically controlled hydrostatic transmission incorporating wheel slip control, is another innovation. The performance and operator acceptance of the machine has led to adoption of most of the concepts in a new machine now being put into production.

Jan 1, 1987