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By Lee M. F, Guilfoyle K

A large hard rock rib pillar was recently preconditioned at Mt Charlotte mine using a novel blasting technique. The motivation for trialling this procedure was a history of past pillar failures, with associated seismicity. Design studies had shown that a new proposed pillar would be at risk of violent failure, and preconditioning was used in an attempt to reduce this risk. Preconditioning by blasting involves physically modifying a selected zone of ground in advance of mining, then forming the pillar so that it incorporates that zone of ground. The modified rock in the zone is intended to allow extra closure (yield) of the pillar in response to mining-induced stress changes. The ground modification was done by tight firing a blasthole array to fracture the rock. The blast design comprised pairs of pre-split blastholes to create a series of short cracks across the target zone, followed by main blastholes to fracture the rockmass between each pair of cracks. A monitoring program was used to establish whether or not the preconditioning was effective. It included conventional extensometers, stress change cells and closure stations, plus a seismic monitoring system. To-date, stoping is complete on one side of the pillar and has just commenced on the other. Results show significant movements within the preconditioned zone and on geological structures in the pillar, as well as lower stress in the pillar compared to an adjacent non-preconditioned site. The preconditioning technique can be applied elsewhere, provided its purpose, mechanism and side effects are understood. Benefits are likely to include more assured production, and successful pillar recovery even in high stress situations.

Jan 1, 1995

The Prince Lyell Mine has been the major production source at Mount Lyell since under-ground mining commenced in 1972.Three lifts of stopes have been mined to date, with the fourth, the 40 Series lift, to commence production this year. As the mine has progressed deeper, the ore haulage system has evolved to accommodate the mine's economic circumstances while maximizing efficiency.In the first, or 10 Series lift of stopes, ore was removed from drawpoints by L.H.D. units and tipped directly into rakes of 7 tonne rail cars. The original concept for deeper stoping lifts entailed L.H.D.'s tipping into long ore passes, rail haulage, underground crushing and hoisting to surface via the No. 1 Shaft. The suspension of the No. 1 Shaft project in 1976, due to economic difficulties, lead to the intro-duction of diesel truck haulage of ore, initially via the internal Prince Lyell Decline and now to surface via the Main Decline.

Jan 1, 1985

By Howell M. W

The purpose of this paper is to outline the main points in the construction of the various types of wire ropes more commonly used for winding in Australia; and the maintenance of the ropes, and cage and skip safety gear as practised at the South mine, Broken Hill.It should be mentioned that both of the shafts at present in use are dry, and both downcast with or without the assistance of the two exhaust fans normally in use: Night shift and week.-end overtime are practicaly non-existent.Thus, during night shift, the cages in No. 7 shaft are landed on the chairs at the surface, providing efficient covers for the· shaft, and allowing the maximum amount of rope to be wound on to the drums. This also applies to the cages of both No. 7 and No. 4 shafts during the week-ends.These factors, combined with electric winding and skip haulage, are calculated to obtain the best use of the ropes when properly attended.WINDING ROPES-TYPE AND CONSTRUCTIONThese ropes may be divided into four main types which will include the more commonly used constructions(a) One-size strand.(b) Warrington strand.(c) Flattened strand.(d) Locked coil.1. One-size strand as the name implies, is a rope the strands of which are constructed 9f wire of the one size.Usually the strands are of 7, 19 or 37 wires.

Jan 1, 1940

The current quantity of rejects from coal beneficiation in Australia represents 20 to 25% of raw black coal production. Approximately 80% of the rejects are derived from coarse processing for particles in the 200mm to 0.5mm size range. The safe and enviornmentally acceptable storage of coarse coal rejects is of interest to coal mining companies. Additional public benefit would be derived from the utilisation of a waste product as a source of fill material for civil and mining engineering applications. BHP Engineering has taken a leading role in the design for storage and utilisation of coarse rejects from two mines associated with the Broken Hill Proprietary Conipany Ltd. The tailings dam at Stockton Borehole Colliery (N.S.W.) is to be raised and a study by BHP Engineering has shown that coarse rejects are suitable for the formation of the supporting embankment surrounding a compacted clay core. Transportation and storage of coarse rejects at the Thiess Dampier Mitsui Riverside Mine (Moranbah, Qld) is achieved by a conveyor leading directly from the coal preparation plant to a discharge stacker on the crest of the rejects stockpile. Production of coarse rejects was higher than anticipated for the initial dump design. BHP Engineering has completed a review of dump design with emphasis on safe operating conditions for the conveyors and stacker system. Data on the geotechnical properties of coarse rejects from Australian coal mines are presented. Coarse coal rejects are a material which should not be considered as waste, but as a potentially valuable resource for many future applications. Appropriate engineering design for the storage and utilisation of coarse rejects would result in an improved environment and economic benefits for the Community.

Jan 1, 1987

By Bevan JE

The US Bureau of Mines is conducting research to improve the health and safety for underground coal miners, and the efficiency of the mining systems that are used. In 1986, the Bureau began a major research effort on the technology for computer-assisted mining systems for underground coal mines. The initial target was technology for continuous mining machines that would allow them to extract coal by computer-assisted operation. Technology areas being investigated include guidance systems, machine condition systems, computer systems, machine control, human-machine interfaces and planning. In each of these areas, individual system development has progressed to where underground testing of these systems will begin in 1991.In addition to coal extraction, the Bureau has also begun research for the development of technology for computer-assisted roof bolting. The Bureau is developing technology for a "smart" roof bolter that would be able to sense and analyze strata conditions to determine the requirements to provide a competent roof. The system would determine the location of the hole, drill the hole to length, and select and install the appropriate bolt.

Jan 1, 1991

By Warner N. A

There is an inherent problem in producing simultaneously lead, zinc and copper as metals in a single polymetallic smelting furnace. It relates to the condensation of lead and zinc from the gas phase under vacuum conditions such that metals in bulk form, either solid or liquid, are obtained as products rather than a fume or dust containing both metallic and non-metallic components. To understand this phenomenon, it has been necessary to establish mathematical models with computer simulation to identify the process requirements for effecting the objective of maximum bulk metal production with minimum fog formation. The theoretical framework of simultaneous heat and mass transfer involved in condensation from gas mixtures containing a non-condensable gas has been extended to the high temperature and reduced pressure conditions. These apply to new technology for polymetallic smelting now being developed in a project currently funded jointly by the Commission of the European Communities and the Mineral Industry Research Organisation. Under the right conditions it is theoretically possible to condense out both lead and zinc with minimal fume formation, but in all practical cases it is anticipated that some circulating load for reversion back to the smelter will be needed.

Jan 1, 1989

By A S. Venkatesh, A Das

The Precambrian iron ore of Singhbhum-North Orissa region of eastern India occurs as part of the horseshoe-shaped broad synclinorium known as the Iron Ore Group (IOG) of rocks, which hosts the most important iron ore deposits in India. The Jilling-Langalota iron ore deposits are part of the IOG. Detailed mineralogical characterisation of different ore types has been carried out using transmitted and reflected light microscopy. Scanning electron microscope-energy dispersive spectroscopy (SEM- EDS), X-ray diffraction (XRD) and X-ray fluorescence (XRF) have also been used with a view to test the amenability of these ore types for beneficiation requirements. It has been observed that haematite, martite and goethite are the main iron-bearing minerals. Kaolinite and quartz are the major gangue mineral phases. Considerable mineralogical, textural and compositional variations have been observed among the different ore types. Characterisation data reveals that the massive and hard-laminated ores are of higher grade with very few interlocking textures having haematite and martite as major mineral constitutents. The soft-laminated lateritic and friable ores are relatively low-grade varieties containing various proportions of impurities with complex interlocking textures. The soft-laminated and lateritic ores are porous in nature and contain friable oxide and hydroxides of iron along with kaolinite, gibbsite and quartz. The occurrence of kaolinite, gibbsite and hydrated oxides along the cavities and weaker mineral planes of haematite and martite has been observed. The friable nature and high alumina content of these ores are attributed to these secondary phases. The nature of these ores is responsible for producing large amounts of alumina-rich slime during mining and handling operations. Suitable beneficiation schemes have been recommended for each type based on detailed characterisation investigations on these ores.

Jan 1, 2007

By Gordon N

The in situ behaviour of claystone floors associated with the Wallarah, Great Northern and Fassifem Seams has been studied using a comprehensive suite of stress and displacement monitors. The instrumentation was supplemented by in situ and laboratory testing of the claystone materials. The instrumentation demonstrated that the presence of claystone floors is associated with floor heave, extra rib spall, and settlement of the pillar into the floor. Horizontal floor extensometers showed that the depth of extrusion of clay was limited to 1-2 in. A pore pressure transducer installed in a claystone floor demonstrated the possible existence of short-term undrained behaviour of the claystone. Long term swelling of destressed claystone was also documented. Settlement of pillars into claystone floors can be analysed using simple elastic theory. The assumption of plane strain is valid for most claystone thickness/pillar width aspect ratios. Floor heave can be analysed using bearing capacity concepts. However, it is considered that heave is the result of local bearing capacity failure in the rib spall zone. The advantage of this model is that the bearing capacity equation can be applied without resort to unrealistically high factors of safety.

Jan 1, 1992

By Lewis W. H, Leigh M. C, Mayercheck W. D

The U. S. Department of Interior's Bureau of Mines, in conjunction with a cooperator in the U. S. A., are developing a new highwall mining system (HMS) for coal extraction in unreclaimed and active contour strip mines. This prototype system is comprised of a computer-based remote control (CBRC) system to monitor and remotely control a thin-seam continuous miner (TSCM) and a 76*m long multiple-unit continuous haulage (MUCH) conveying system, plus other manually- operated support equipment located on the highwall bench. The TSCM and MUCH coal haulage system are both controlled remotely by a single operator in a protective enclosure at an ergonomically- designed workstation located on the highwall bench. Two other personnel work on the bench to operate other support equipment. Full-scale mock-up fabrications were employed in the design of the unique remote control operator workstation. The HMS should allow the safe and economical exploitation of increased coal reserves where they outcrop in hilly regions of the United States. It should also be competitive with conventional auger mining and other coal extraction techniques, with a productivity goal at a highwall site of 20 tonne/man-h. Extensive simulated surface tests of the miner and haulage system should be completed in early 1988 at Bureau test facilities at Pittsburgh, Pennsylvania. These will be followed by actual coal production trials of the entire system in 1988 at a highwall site in West Virginia/USA.

Jan 1, 1988

The paper is aimed at mining engineers and other mining practitioners in the metalliferous mining industry who are considering the use of roadheaders and wish to understand the basic geomechanical and operational principles controlling their performance. The paper aims to address metalliferous minersÆ general unfamiliarity with roadheader technology, which is one of the factors which has limited the application of these machines in such mines. The historical development of drag tool mechanical excavation machines is briefly discussed, and factors affecting the application of roadheaders are mentioned. The mechanics of cutting with drag tools is then reviewed as are the effects of these and tool wear on tool performance. The implications of tool performance to roadheader performance are mentioned, the potential benefits of high pressure waterjet assistance are discussed and the relative performances of different tool types and materials are compared. Roadheader performance factors including productivity and utilisation are mentioned, and the state-of-the-art of conventional roadheaders is discussed in the context of machine weight, power and cutting head configuration. The influence of these and rock strength on machine productivity is analysed. Alternative, developing technologies are discussed which may extend the effective use of mechanical excavation into stronger rock masses which are beyond the range of conventional roadheaders. Finally, conclusions on these discussions are presented, along with recommendations for continuing research and development.

Jan 1, 1997

By Singh T, Singh D. P

India has limited resources of coking coal. Most of the coking coal seams are located in Jharia Coalfield. These seams were worked in the past by the bord and pillar system in a haphazard manner, which has resulted in honeycombs of old working. Most of such areas are under fire. In order to meet the demand of coking coal in the 21st century, it is essential that the coal locked due to old underground workings is recovered fully by conducting opencast mining to an ultimate depth of 500 m. The major problem envisaged in conducting opencast mining in such areas will be the stability of pit slopes over voids and the behaviour of subsided material in the pit slopes. An attempt has been made to simulate this complex situation from a specific section of the rockmass of a mine in an equivalent material (EM) model. The old workings existing in upper coal seam (V) were simulated by developing staggered bord and pillar workings in two sections and depillaring them. Opencast mining was conducted for recovery of coal locked due to irregular working in coal seam V. The slope instability caused by intersection of the slope with the void, during frontal working (by shovel-dumper combination) was observed in various situations. In this paper, the technique adopted for simulation of a 125 m thick section of rockmass in an EM model is outlined. Adverse effects of staggered workings and

Jan 1, 1988

In South African gold mines, the types of material requiring transportation to the stoping areas include timber packs, explosives, hydraulic rock props, scrapers, scraper winches, pipes, pumps and backfill material (in areas where backfill is being used). Currently timber packs are broken down to their basic components (log and brick) and are transported into the stope by means of either monowinches or a combination of monowinch and scraper winch. Other materials, such as explosives, hydraulic rock props, scrapers, scraper winches, pipes, pumps and backfill material must be transported by other means, usually by hand or, in the case of heavier items, by chain blocks. With the drive to increase stope advance rates and the rise in the number of miners with HIV/AIDS, there is a need in the South African gold mining industry for an improved material handling system. To meet future requirements, material handling systems should assist miners to transport materials quickly and efficiently. Furthermore, it must be financially viable and economically competitive with current material handling systems. This paper looks at the in-stope material handling efficiency of current monowinch systems and provides solutions to improve efficiency. In addition, the use of in-stope monorails are reviewed and the possible scenarios that will substantiate the use of monorail systems are discussed.

Jan 1, 2003

By T J. Orr

The changing demographics of the mining industry make successful passing of knowledge and skills to the next generation critical. Training methods and technologies are being developed to meet this need. Twenty years ago classroom training was largely a one-way transfer of knowledge through instructor lectures. In contrast, instructors today can use virtual reality technologies to guide trainees as they fully participate in learning experiences. Trainees can interact with the virtual work environment, co-workers, and equipment without being exposed to workplace hazards. The speed of advancement in mine safety, health, and production training shows no sign of slowing in the next 20 years. Researchers at the National Institute for Occupational Safety and Health have studied and participated in the evolution of miner training. A look at training materials they have created in the past and those they are currently developing reveals changes in methods and technologies over time and also key characteristics which have remained constant. Possibilities for the future can be discussed in the framework of an implementation of virtual reality in new miner training sessions. The example computer-based training package teaches new miners to read mine maps and provides opportunity to practice navigation skills in a virtual mine. With this æserious gameÆ, trainees experience the look and feel of moving through an underground coal mine while in the safety of their classroom. During field-testing in 2007, trainees and instructors responded very favourably to this new way of learning. The software was usable by mine trainers with even limited computer expertise and could be installed on the affordable computers they were using for their more traditional slide presentations. The Underground Coal Mine Map Reading TrainingÆs foundation on past successful development strategies and its acceptance by todayÆs instructors and trainees provide valuable lessons for developing training materials, strategies, and technologies for miningÆs future.

Jan 1, 2008

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 L Yang, L Chen, E Hu, D Tang

Online monitoring of particles cumulative percent passing (PCPP) for a target size at hydrocyclone overflow, compared with traditional offline methods, provides PCPP feedback in real time, and is advantageous in enabling energy-efficient comminution, increasing downstream flotation efficiency, and improving upstream resource knowledge. However, existing online approaches are generally costly and bespoke, and some are sensitive to operational changes. Therefore, this study proposes a new low-cost alternative based on accelerometer measurement for online PCPP monitoring in the overflow of hydrocyclones and provides a preliminary experimental investigation under dry condition. The proposed method uses a sensing probe inserted into the overflow pipe of a hydrocyclone to receive particle impact from the incoming slurry, with accelerometers attached to the probe and mounting frame outside the pipe for particle-probe impact detection. As a preliminary investigation before studying particle-probe impact events in slurry, tests under dry condition without fluids were conducted using dry sand particles in free fall from a fixed height. Accelerometer measurements are analysed in both time and frequency domains through root-mean-square (RMS) and fast Fourier transform (FFT). Results show that accelerometer measurements are useful in estimating mass flow rates, which are correlated to the accelerometer output amplitude RMS values in time domain, in a non-linear mapping. Different particle size classes can be identified by examining the accelerometer output amplitude at a known mass flow rate. Different particle size classes feature their distinct signature frequencies (SFs) that can be examined via FFT and the SF is found to be independent of the mass flow rate. The results imply that any PCPP changes can be detected by the change in the accelerometer output amplitude as well as a shift in SF, which demonstrates the effectiveness of using accelerometers to gauge changes in PCPP. Based on the current findings in dry condition, future work will investigate particle-probe impact events in slurry.

Aug 24, 2022

By Sims D. A

This paper primarily describes the application of geology to the different mining methods employed in a large underground mine. The steeply dipping stratiform Silver/Lead/Zinc mineralisation at Mount Isa include up to 28 mineable orebodies. The orebodiea are mined by cut and fill, sublevel benching and sublevel open stoping; the method chosen depending mainly on orebody geomechanics.The sources and methods of data collection, and the interpretation process undertaken, are described. The paper emphasises the different geological input required, by each individual mining method, to provide the necessary production and strata control. This input contributes significantly to the success and efficiency of the operations.

Jan 1, 1990

As a result of high fuel prices and substantial haul distances or vertical lift from pits, the development of large inpit crushing and conveying systems at many open pit operations has occurred over the last decade.The basic criteria that has to be met is that the material is reduced in size to be conveyable. Generally this requires a top size of less than 300 mm.

Jan 1, 1992

The history of potential large scale development at Stawell in northwestern Victoria dates back to 1914, when Great Boulder Mines Limited, of Kalgoorlie, Western Australia, took up options on some of the major mines in the Stawell Goldfield. Despite this and other attempts by various groups over the next thirty years, mining activity on the field gradually dwindled to the retreatment of old mill tailings.A static price for gold and indifferent drilling results prevented a major effort towards reopening the field until the late 1970's. A renewed exploration effort led to the discovery of sufficient reserves to justify installation of a carbon-in-leach gold treatment plant.

Jan 1, 1984

By J Leppinen, B Johanson, R Kalapudas, G McMahon

The Suurikuusikko gold deposit was discovered in 1987 in western Finnish Lapland, 54 km NNE from the town centre of KittilS in the volcanic belt of Central Lapland. It is hosted by tholeiitic basalts in a graphite-bearing albitite breccia. The ore is located in subvertical shear zones characterised by strong albitisation, carbonatisation and sulfidisation. The ore minerals consist of arsenopyrite, pyrite, chalcopyrite, sphalerite, tetrahedrite, bournonite and rutile. Small amounts of pyrrhotite, gersdorffite, jamesonite, bornite, gudmundite, tetrahedrite, stibnite, kermesite, berthierite and native Sb are also present. Gold occurs as invisible and as 1 - 2 ¦m size inclusions in arsenopyrite and pyrite, on their grain boundaries and in fractures. The average amount of gold leached by cyanide is 2.93 per cent. The æinvisibleÆ gold contents were studied in pyrite and arsenopyrite by electron microprobe analysis (EPMA) and secondary ion mass spectrometry (SIMS) at CANMET/ MTL. Gold element distribution images show zoned patterns both in pyrite and arsenopyrite. SIMS analyses range from 343 to 55 ppm Au in arsenopyrite and from 217 ppm down to 0.32 ppm (detection limit 478 ppb) Au in pyrite. EPMA results range from 939 to below the detection limit 24 ppm Au in arsenopyrite and from 267 ppm to below 22 ppm Au in pyrite. Recovery of the refractory gold ore was studied using grinding, flotation, bio-oxidation and cyanidation tests. A sulfide bulk concentrate containing 40 ppm Au was obtained by flotation at 90 per cent recovery (As content 5.5 per cent, S content 22 per cent, and mass recovery 15 per cent). The grinding fineness in flotation was P80 -100 to 120 ¦m. At the original fineness the cyanidation recovery from the concentrate was lower than ten per cent, after ultra-fine grinding P80 -10 to 2 ¦m the Au recovery was less than 17 per cent. After bio- oxidation, Au recovery of 95 per cent was obtained in carbon-in-leach (CIL). The bio-oxidation time was two weeks in laboratory test, but after regrinding the oxidation rate was faster and recovery of Au higher. However, the selected method for the mining to be started in summer 2008 is open pit mining and mineral processing methods sulfide flotation and pressure oxidation in an autoclave. The ore reserves were estimated 31 December 2007 as: Probable 18.2 Mt with 5.1 g/t Au, Indicated 5.4 Mt with 3.0 g/t Au and Inferred 10.8 Mt with 3.4 g/t Au. The production capacity will be 3000 t/day.

Jan 1, 2008

By Whittaker B. N, Reddish D. J

This paper presents the physical modelling results of subsurface fracture development associated with Iongwall mining operations and an application of image processing techniques to interpretion of the results. Physical modelling results haióbeen obtained by employing a large sand and plaster model loaded purely by gravity as a means of fracturing the subsurface strata above the longwall excavation. The results have shown fracture development and crack propagation as a longwall face advances and demonstrated that the strength of stratified rocks, the presence and position of a weak band-, and the extraction thickness, have significant effects upon the overall fracture patterns above the excavation. Binary images of fracture patterns were scanned from the black and white photographs of the tested models using an image analyser coupled to a video camels. These images were manipulated by a custom written C program which allows the images to be processed in both vertical and horizontal direction. The images were filtered to quantitatively differentiate between vertical and horizontal fracture intensities. The vertical fracture intensity is particularly important as vertical fractures are considered to provide the main avenues for surface and subsurface water inflow into the excavation. The use of the image analysis techniques has shown a promising improvement in image enhancement and in model results interpretation in a quantitative manner. The numerical nature of the image analysis results will allow further statistical comparison with other modelling techniques to be undertaken and significantly increase the scope for use of the modelling technique results.

Jan 1, 1992