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By Lauricella P. F, Hendri D

In the Mesel sediment-hosted disseminated gold deposit, the spatial distribution of hydrothermal alteration is controlled by steeply dipping faults and shallowly dipping lithologies. Hydrothermal alteration of carbonate rock is characterised by decalcification, dolomitisation and silicification. Intense argillic alteration occurs in a laccolithic andesite intrusion adjacent to decalcified and silicified carbonate units. Sulphide minerals (pyrite, realgar, orpiment, stibnite and cinnabar) accompany hydrothermal alteration and precious metal mineralisation. The trace elements Ag, As, Sb and Hg are zoned spatially throughout the deposit. Mesel contains a mineable gold reserve of 7.8 million tonnes at 7.3 g/t Au. Gold mineralisation is preferentially localised in carbonate rocks adjacent to and beneath the andesite intrusion. The ore body consists of a central, near-vertical, high grade "feeder" system flanked by tabular, inward dipping, moderate grade "ouflow" zones. Mineralisation is controlled predominantly by two steeply dipping faults with high grade (>10 g/t) gold zones centred about structural intersections and fault splays. Gold is submicron size and locked in very fine grained (

Jan 1, 1995

Pasminco is actively addressing the optimal utilisation of the known orebody at the Broken Hill mine, in addition to actively exploring for economic mineralisation in the region. As part of the policy of better utilising the known mineralisation a major upgrade of geological systems at the mine was initiated. The software chosen for this change was Maptek's Vulcan, mainly because of the ease of use of this package. Rather than having numerous data sources in varying software packages the mine aimed to limit interfaces and packages. The decision to upgrade the mine's software was not taken lightly, especially in view of the inature stage of Broken Hill mining operations. However, the current mine life of Pasminco Broken Hill mine is I I years, which is longer than many new mines setting up in Australia today. Also, a more sophisticated system brings with it a better understanding of the economic mineralisation, possibly extending the mine life further. The process of moving the Broken Hill databases into Vulcan was a huge task which included, database transfer, digitising, wire framing, modelling and eventually ore resource calculation. To ensure the validity of the new ore resource accounting system, the existing system was run as a duplicate for the introductory year, providing a comparison and if necessary a safety net. The benefits of such a change, however, became apparent almost immediately. Area geologists realised the opportunity to revise geological interpretations in their areas of responsibility, enabling them to obtain a better understanding of orebody morphology. Three- diniensional analysis provides an excellent method by which review of ore targets both in the underground and mine lease exploration areas can he made. As each new find of mineralisation enters the system and hopefully extends the mine life, the opportunities for further mineral exploration in Broken Hill area by Pasminco are enhanced.

Jan 1, 1997

Pulverised coal firing was pioneered in the cement industry prior to the turn of the century. Ash from the coal is absorbed into the mix in the kiln and replaces secondary materials. With high purity limestone coal with high ash content can be used. Fuel cost is a major part of the total manufacturing cost. Cement plants are thus quick to respond to fuel price changes and will use low grade fuels if there is a price advantage. Combustion conditions in a cement kiln differ markedly from a boiler. Flame length is determined by air/fuel mixing but because of fixed secondary air conditions this depends on primary air momentum. Volatile content has some effect on flame length but this can be offset by coal fineness. Much of the heat for cement production is for limestone calcination which is a low grade energy requirement. By allowing long residence time in separate direct fired vessels which then feed the high temperature kiln the energy of materials such as oil shale, tyres and lump lignite can be utilised.

Jan 1, 1987

By Grieve BL

For a blast to be successful both heave and fragmentation must be satisfactory. Amongst the major factors influencing blasting are rock properties. This paper considers the effect of rock density on fragmentation and heave and how better results can be achieved in dense ore. Patterns which increase the heave and give better fragmentation are examined and the application of theory to the blasting of the Dales Gorge Haematite, density 4.2 - 4.5 t.m.,3 is then discussed. The drilling of staggered patterns instead of square patterns and a shallower 'V' initiation system has given better heave and fragmentation. This practice has re- duced backbreak and improved toe conditions; these factors have resulted in increased load ing rates. There has been an increase in the lump/fine ratio which is consistent with the theory although other factors such as ground conditions could have contributed.

Jan 1, 1978

Syferfontein Colliery, part of the Sasol group of companies which specialises in the field of petro-chemical production, was established in 1990. The mine is situated about 150 km east of Johannesburg, South Africa. Two coal seams are mined, utilising two 75 m3 draglines, shovels and a fleet of 177 ton rear dump trucks. The mine will reach its full production capacity of seven million tonnes per annum in 1992. During the planning period, prior to the establishment of the mine, management were confronted with the unstable socio-political environment in South Africa which could jeopardise the eventual success of the mine. They consequently conducted a strategic planning exercise to determine guidelines for mine planning to improve the chances of success in this unstable third world environment.The strategic guidelines formed the basis for specific actions taken during the planning and commissioning of the mine. Specific actions were taken in the field of operating cost, labour relations, working environment, logistics and the general environment. First results indicate that these actions have played a major role in the success of the mine to-date. This process can be utilised by others facing similar or even totally different uncertainties.

Jan 1, 1992

Results from current NERDDC funded research into the geotechnology of highwall trench mining methods have clear implications for mine planners in the areas of blast design, trench shape, location of the surcharge spoil and remnant coal pillar design.Adoption of successful smooth wall blasting techniques not only removes safety hazards from the trench face, but limits development of bedding partings at the seam contacts that interrupt the smooth transition of stress across the coal seam.

Jan 1, 1992

By C Mark

Coal bursts involve the sudden, violent ejection of coal or rock into the mine workings. They are a particular hazard because they typically occur without warning. During the past two years, three US coal miners were killed in two coal bursts, following a six-year period during which there were zero burst fatalities.This paper puts the US experience in the context of worldwide research into coal bursts. It focuses on two major longwall mining coalfields that have struggled with bursts for decades. The Utah experience displays many of the ‘classic’ burst characteristics, including deep cover, strong roof and floor rock, and a direct association between bursts and mining activity. In Colorado, the longwalls of the North Fork Valley (NFV) also work at great depth, but their roof and floor strengths are moderate, and most bursts have occurred during entry development or in headgates, bleeders or other outbye locations. The NFV bursts also are more likely to be associated with geologic structures and large magnitude seismic events. The paper closes with a brief discussion of how US longwalls have managed the burst risk.CITATION:Mark, C, 2014. Coal bursts in the deep longwall mines of the United States, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 33–40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Gray N. B, Floyd J. M

To gain further understanding of the operating efficiency of the BHP Slab and Plate Products Division (SPPD) RH vacuum degasser, physical and mathematical model studies of the process have been undertaken. The purpose was to investigate how the various process parameters affect the liquid circulation rate, to visualise the flow patterns, and to identify and eliminate the cause of localised wear in the downleg. In the physical model mixing times were measured using an acid tracer technique. The results were applied to predicting trends in times required to obtain homogenous melt composition under varying conditions. A 2-dimensional mathematical model describing the liquid metal flow has been developed using the PHOENICS fluid-flow package. The physical model results were simulated and incorporated into the mathematical treatment and an improved design for vessel geometry is proposed. The effect of rounding the downleg entrance or installing a baffle between the legs is discussed.

Jan 1, 1987

Better quality at lower cost is today's formula for remaining competitive in a world market. For an integrated steel company, high quality low cost steel production must originate before the blast furnace. In 1979, when U.S. Steel initiated a Quality Management Program throughout its steelmaking operations, efforts began at the coal, ore and flux mines. The objective was to improve the quality and reduce the variability of the critical parameters for steelmaking raw materials, to get the blast furnaces, and subsequently the melt shops, under optimum control. The general details of U.S. Steel's Quality Management Program are discussed and how it was used to promote the desired improvements in steelmaking raw materials. Some of the outstanding results obtained by the cooperative efforts between the mines and the steel plants are reported. The lessons learned by U.S. Steel were through upgrading existing operations and facilities. These principles should now be applied to new projects and the benefits of good quality management should commence from the time new projects are Commissioned.

Jan 1, 1986

By Martinick WG

In July 1986, Cable Sands (W.A.) Pty Ltd commenced mining for mineral sands at Minninup, approximately 16 km south of Bunbury, Western Australia.The area being mined is from the heel of the foredune to the rear of the hind-dune. The vegetation is mostly native vegetation with some old degraded pasture.The mining operation will be by suction cutter dredge, with continuous dredging, mineral separation and re-depositing of the sand.

Jan 1, 1986

By H Austrheim, A K. Engvik, A Putnis

How aqueous fluids move through rocks and minerals is a question of possible pathways and mechanisms. Existing pathways such as fractures and grain or mineral boundaries provide obvious channels for fluid movement. We show how minerals reactive in the presence of an interfacial fluid can be replaced by new product phases through a process of interface-coupled dissolution-reprecipitation. A resulting porosity in the new phase provides a new pathway for fluid movement and therefore mass transport through the mineral, which progressively reacts at a moving interface. Eventually fluids of new and changing composition can pass through originally solid minerals and move on further, taking remobilised elements with them, to be reprecipitated whenever the chemical and/or physical conditions allow. One such example is albitisation of rocks associated with mineralisation.

Jan 1, 2008

A modular computer-based monitoring system for mines is dis-cussed. The system consists of the following modules : production moni-toring system HADES, methane monitoring system CMC, seismoacoustic and seismometric systems SAK and SYLOK, communication systems. The system enables one to compose flexible,` economic structures according to the specification of a mine. Application of microcomputer-based monitoring and control systems in coal preparation plants also is discussed.

Jan 1, 1985

By T Hayward, G Lane, M Phillips

In December 2004 Phu Bia Mining Ltd commissioned Ausenco International Limited to conduct a feasibility study for its Phu Kham copper-gold project located in Laos. The feasibility study for a mining and processing operation treating 12 Mtpa of ore averaging 0.56 per cent copper and 0.25 g/t gold to produce an anticipated annual average 200 000 t of concentrate containing 25 per cent copper was completed in early 2006. The plant design incorporates a single processing line and includes a gyratory crusher, overland conveyor, coarse ore stockpile, SAG and ball mill grinding circuit, flotation circuit including regrind and three stages of cleaning, concentrate dewatering and concentrate load-out facilities. The Phu Kham copper-gold mineralisation comprises two principal styles: stockwork-disseminated and banded-massive sulfide within skarn limits. Primary copper in both mineralisation styles occurs as chalcopyrite and secondary copper sulfide minerals. Skarn includes the copper and gold mineralisation contained in pyrite, silicate, magnetite and haematite skarns, and in quartz-pyrite altered sediments. Both the stockwork-disseminated and banded-massive sulfide ores contain relatively high proportions of pyrite relative to the copper and gold mineralisation. Thus, the flotation metallurgy of the Phu Kham orebody is characterised by the need to reject a high proportion of the pyrite during differential flotation to yield a concentrate grade of approximately 25 per cent copper. The rejection of pyrite is accompanied by the rejection of some copper and gold and can result in modest metallurgical recovery. Consequently, the greater the pyrite content, the lower the expected copper and gold recoveries. The relative pyrite content is expressed on the basis of sulfur:copper ratio. For Phu Kham ores, the sulfur:copper ratios are in the range eight to 14 on a blended annual basis, but can be greater than 20 in the skarn components. Higher grades of copper and gold are also present in the skarn mineralisation. The design concepts for the concentrator were influenced by the need to provide a low capital cost approach for the project due to the relatively low grade of the ore and the modest metallurgical recovery. The concepts used to minimise capital cost whilst retaining operating and maintenance flexibility are discussed, together with the metallurgical challenges imposed by the high pyrite mineralisation.

Jan 1, 2007

By N Meyer

This paper presents a research project referring to the stability of submerged walls of open pit mines and the actual state of development. Obviously the slope stability analysis is always a rather complex problem, because it is difficult to reduce the problem to a design scheme and to define the available in situ soil strength. Especially the design of submerged slopes represents a problem. The state-of-the-art slope stability analysis is based on a simplified modelling of slope failure and soil behaviour and with this predicted stable slope inclinations of sand slopes below water-table are less then half the angle of internal friction. Slope angles calculated like that canÆt satisfy the mining companies. One of the problems that have to be solved is the reliable determination of the long-term stability of non-cohesive, submerged slopes, which is not only dependant on geotechnical and hydrogeological parameters of the subsoil, but is also significantly influenced by how the slopes are made. The research project points at the relations between mining and geotechnical engineering with the main aim to find a more suitable stability analysis which takes both soil behaviour and mining influences into account.

Jan 1, 2003

The planned extraction of deeper copper ore at Isa Mine has necessitated a review of existing equipment and methods to contain costs and improve working conditions. Mining is in progress for a crushing-conveying system to serve the deeper southern areas of the 1100 Orebody. This system will permit direct tipping of ore to the crushers and conveying of the crushed ore by cable belt conveyor to existing shaft loading facilities, a distance of about 2 km. To develop part of the conveyor drive a new machine will be used, the Robbins MM120 Mobile Miner, a joint development project between The Robbins Company and Mount Isa Mines Limited. The Mobile Miner uses a rotating cutting wheel to excavate headings 3.7 m high and from 4.7 m to 7.5 m wide. To ventilate the deep crusher complexes and associated development at high virgin rock temperatures, a refrigeration plant will be built on surface to reticulate chilled water underground. Bulk cooling of air to the 3000/3500 Orebodies and the southern crushers will be combined with the reticulation of chilled service water to the lower workings of the mine.

Jan 1, 1984

By A J. Moore

To control the airblast from blasting to regulatory limits at environmentally sensitive sites near the Collinsville Coal Mining Operations, it has been necessary for Thiess Mining to incorporate a wavefront reinforcement analysis model in the predictive environmental airblast design. Controlling airblast from cast blasting 70 m high faces with 2000-3000 kg of explosives per hole within 700 m of houses presents a considerable challenge to the blasting personnel. This paper describes the model used and summarises the results of an investigation designed to quantify the increase in airblast indicated by wavefront reinforcement diagrams to further calibrate the model for future prediction.

Jan 1, 2004

By G M. Tranell, M Tangstad

The CO2 footprints in the production of Mn-ferroalloys and silicon/ferrosilicon are correlated with the fossil carbon consumption. The CO2 emissions may be reduced in the Mn-ferroalloy process by increasing the degree of prereduction and reduction of carbonate materials, while the silicon/ferrosilicon process is optimised based on silicon yield. By changing the fossil reductant into biogenic reductants, the global warming potential will be decreased even more. Even if the reductants are biogenic reductants, there will still be a global warming potential (GWP) in eg the electrode consumption and the CH4 emissions in the charcoal production. To reduce the use of fossil reductants there are also more disruptive technologies like the use of H2 that at least for the silicon production is on a very low technology readiness level (TRL). Using metallothermic processes will reduce the use of carbon but requires carbon neutral metal reductants. Electrowinning can have low CO2 emissions, and the electrowinning of pure Mn is a technology of high TRL. Salt and oxide electrolysis is under investigation for both Mn and Si production however the research is still on a low TRL. The use of CCS/CCU (carbon capture storage/utilisation) is a part of obtaining carbon neutral processes. Last, the energy mix used for these energy demanding processes is discussed.

Aug 21, 2024

High resolution seismic profiling has proved a cost effective tool for defining the structure and seam geometry of Late Cretaceous-Late Miocene age lignite deposits in the South Island of New Zealand since 1981.In 1985 a total of 45 km of Mini Sosie seismic reflection was carried out in the Benhar, Hawkdun and Ashers-Waituna deposits as part of a major multidisciplinary resource investigation funded by the Liquid Fuels Trust Board. For each deposit the seismic programme involved integrating four or more intersecting Mini Sosie traverses with a grid of 1000 m spaced geophysically logged drillholes. The objective was to detect faults, with displacements ranging 30 - 100 m, which might impede mining using bucket wheel excavator systems at depths down to 300 m below surface.In general the quality of processed seismic data was high and with the assistance of ynthetic seismograms and other geological information, it was possible to identify a number of significant previously unknown faults. The success of this seismic programme ha shown that high resolution seismic profiling, used in conjunction with relatively low density drilling, can produce valuable structural and tratigraphic information at an early stage of open pit mining investigation.

Jan 1, 1989

By Y Li, L Zhang, G Li, S C. Dominy

Qiagong skarn iron (copper) deposit is located in Xietongmen County of Tibet, China (N 29¦52Æ14.9ö, E 88¦24Æ10.3ö). It is situated at the middle-western Gangdese porphyry copper-belt. Mineralisation is related to a Himalayan porphyry intrusion, with the mineralised body occurring at the contact zone between the Tertiary Takena Formation carbonate rocks and Himalayan monzonitic granite porphyry. The melt, melt-fluid and fluid inclusions were observed in early quartz, with most abundant fluid inclusions in quartz, calcite and garnet from the skarn. The geology and inclusion assemblage show a close relationship between iron (copper) mineralisation and a Himalayan porphyry intrusion. Based on preliminary inclusion studies, this paper discussed the characteristics, evolution of ore-forming fluid and affiliation to the Himalayan porphyry intrusion. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

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