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By N Tuffs, R Peace, S Xue

Mine gas control is a major issue in most of the gassy underground coal mines, due to its direct impact on safety, production delays and cost of production. Analysis of the gas data, from different collieries in Australia showed that longwall gas emissions have increased substantially over the years. Simply increasing the number of goaf holes in the panel or decreasing goaf hole spacing seems not to be effective, in controlling high goaf gas emissions. A major research project has been undertaken by CSIRO in collaboration with mine sites to address this goaf gas control issue with the aim of developing effective and optimum goaf gas drainage strategies. The project has combined extensive field studies with computational fluid dynamics (CFD) models, to characterise goaf gas flow patterns and develop effective gas control strategies. The research work specifically involved review of gas control issues at field sites, goaf gas monitoring, tracer gas tests, CFD simulations and extensive field trials. Field demonstration studies of the new optimum strategies have been conducted at two collieries in Australia. The project results have shown that the optimum strategies were highly successful, in improving the overall efficiency of goaf gas drainage systems, at both the field sites. Results of the goaf gas flow characterisation studies and field demonstration studies are summarised in this paper.

Jan 1, 2005

Optimisation of mining projects is directly related to effective and efficient management of risks through the life cycle of mining projects. Effective and efficient management of risks must include explicitly all aspects of Occupational Health and Safety (OHS) through the life cycle of mining projects. This paper presents a different scale of OHS in the context of the optimisation of mining projects. Meaning of risk through the project life cycle is explained. Complex relationships between numerous risk, safety, knowledge, culture and change variables, and project life cycles are shown. The key element developed in this paper is a multi-disciplinary knowledge base that is necessary for constructive development of risk management and OHS models through the life cycle of mining projects.

Jan 1, 2003

By Waijun Cheng, Guilin Xie

A microcomputer control system prototype of a Switched Reluctance drive for storage battery electric vehicle in coal mines is developed. The paper introduces the hardware components, the control strategy and the software unit. It is shown that

Jan 1, 1998

By G W. Wilson, P Ritchie, N A. Currey

The design and rehabilitation of potentially acid forming (PAF) waste rock dumps is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed, and the climatic setting. The æstore and releaseÆ cover system developed to manage acid rock drainage (ARD) from mineralised waste rock dumps at Kidston Gold MinesÆ open pit operations in the semi-arid climate of North Queensland, Australia, has been monitored for seven years. The paper describes the philosophy behind the design of the PAF dump and æstore and releaseÆ cover system and the adaptation of the cover system over time to suit KidstonÆs conditions. The results of monitoring over the seven years since the first cover was constructed are presented, and the approach being taken at Kidston to ensure that the risk of impacts from any residual ARD is accommodated and to facilitate lease surrender are described. The Kidston story is a valuable case study of a successful approach to remediating an identified source of ARD in a semi-arid climate, which has actively engaged all Stakeholders.

Jan 1, 2003

By Milner SC

Four quartz latite rheoignimbrite units (units I to IV) mapped in the Goboboseb Mountains have been traced to their eruptive source, the Messum intrusive complex; this is a complex multistage ring structure (18 km diameter) with well defined gabbroic, monzonitic, and syenitic intrusive phases, and a central ring zone containing mixed rhyolitic to latitic agglomerates. Three of the four quartz latite units are correlated with the upper and lower (2 units) Springbok quartz latites outcropping some 90-130 km north of McIsum. This implies minimum volumes of 300-500 km for wits I and III (Lower Springbok) and 2200-2600 km for unit IV (Upper Springbok). This latter unit is still ti 300 m thick at its outcrop limit, some 130 km from Messum. Each of the four units represents single cooling units. Lithologically, each can be divided into three zones: A basal, dark grey to black flinty or glassy zone, often with highly attenuated fiamme (ressembling flow banding); a central massive and strongly recrystallised zone; and an upper variable zone which exhibit breccias, contorted flow banding, and amygdaloidal to pumiceous clasts. Their overall characteristics tend to be intermediate between ash flows and lava flows. The rheoignimbrites are interpreted as the oproducts of dense, high temperature (950¦-1100 C) ash flows which underwent rheomorphism and lava-like flow prior to their final cooling.These large scale eruptions are related to the initial rifting of Africa and S. America, possiby in response to a major hot spot.

Jan 1, 1990

By Jingmin Xin, Wenhua Xing, Zongxin Huo, Hongzhang Chen

Drawing up the successive plan for mining and development is a very important and regular plan work. The expert system of the successive plan for mining and development drawn up by computer is developed on the basis of network, computer simula

Jan 1, 1998

By Parkes DB

The excavation of sandstone of generally medium strength for the Liverpool Link Line by Dosco Mark 2A Roadheaders has demonstrated the versatility and good performance of road- headers in suitable rock formations. A description is given of the strata traversed by the tunnels together with descriptions of equipment and crews, excavation sequences, operating difficulties and the results achiev- ed. In addition tunnel construction is des- cribed for a difficult section where there was only O.Sm clearance between invert and a four lane vehicular tunnel below, and O.5m clearance between tunnel crown and a century old sewer above.

Jan 1, 1976

By S Januszewski and, G Dirom, D Christensen

Four field test plots were constructed in 1998 on a sloped waste rock surface at the Myra Falls Operations of Boliden Westmin (Canada) Limited to evaluate hydraulic performance of alternate cover system designs. The field test plot cover systems were designed to control oxygen ingress and water infiltration to the underlying waste rock while providing a medium for a grass and legume vegetation cover. The test plots consisted of a bare waste rock surface (control plot), and three additional plots consisting of native compacted till placed directly on the waste rock surface, overlain by non-compacted till. Two of the test plots included a compacted till layer ameliorated with flyash and bentonite, respectively, to improve moisture retention and reduce permeability. The third test plot consisted of a compacted layer of native till overlain by non-compacted till. A performance monitoring system was installed in each test plot to evaluate net percolation and oxygen ingress to the underlying waste rock. In addition, each test plot has profiles of matric suction, water content, and temperature sensors installed at up-slope and down slope locations. A review of four years of monitoring data shows that the compacted till/bentonite cover system has been most successful in limiting the infiltration of meteoric waters and oxygen ingress to the underlying waste rock material. The compacted till/flyash and compacted till cover systems have produced similar net percolation results and neither have functioned well in maintaining an oxygen ingress layer throughout the year. The amelioration of bentonite with till to produce a compacted barrier layer shows promise in reducing water and oxygen ingress at the MFO site, while the incorporation of flyash with the till did not result in a significant increase in performance. The field performance data clearly demonstrates the need for developing field trials prior to full-scale construction, as opposed to relying solely on an un-calibrated numerical modelling to design the full-scale cover system.

Jan 1, 2003

The West Fork project is located in Reynolds County, Missouri, in the mineralized zone referred to as the Viburnum Trend. The West Fork orebody has a calculated ore re- serve of 13 600 000 tonne (15 000 000 st) con- taining 5.5 per cent lead, 1.2 per cent zinc, and recoverable values of copper and silver. A total of 64 600 tonne (71 200 st) of lead concentrate and 11 300 tonne (12 500 st) of zinc concentrate will be produced annually. The mill was designed to operate at an average capacity of 3450 tonne/day (3800 st/day), based on a 95 per cent availability factor. The mill will operate 24 hours a day, 5 days a week, with maintenance performed, as needed, on weekends. The mine will operate on an identical schedule; but the underground, pri- mary crushing will operate on a six hour/shift, three shift/day schedule. The 1.07m x 1.22m (42in x 48in) jaw crusher will produce a minus 20cm (8 in) material at an average rate of 191 tonne/h (211 st/h). The jaw crusher has almost twice the throughput capacity required, but the decision to install that size of crusher was based on the need to handle over sized rock in the ore.The coarse crushed ore will discharge into a 180 tonne (200 st) skip pocket, which will allow up to a one hour surge capacity prior to hoisting. Hoisted ore will discharge into a 900 tonne (1000 st) storage bin located adjacent to the headframe. The skip pocket and coarse ore silo comprise the total ore storage capacity. The concept of having no intermediate fine ore storage between the secondary crushing and grinding sections was borrowed from the Brushy Creek Mill of St. Joe Minerals, which operates adjacent to the West Fork property. Integration of the secondary crushing and grinding circuits has worked ' successfully for years at the Brushy Creek Mill. The most obvious advantage to eliminating the intermediate fine ore storage is'capital expen- diture savings. The capital expenditure savings include the cost of silos, feeders, and the cost of additional conveyor length and eleva- tion. Savings in operating costs will also be gained, particularly in reduced maintenance costs. Other factors which influenced the decision to eliminate fine ore storage were the simplicity of the secondary crushing sec- tion and the limited area available for con struction of the facility

Jan 1, 1978

An effective production control system should maximise recovery of economic material from the resource. To do this, internal waste must be accurately delineated and efficiently removed. Achieving this is most difficult in low grade blocks just above and just below the cut off grade, where ore:waste separation follows assay or statistical, rather than geological boundaries. Difficulties arise from sampling errors, configuration of the economic mineralisation, and local variations in geology. Mine bench parameters and mining equipment size apply further constraints to the actual field separation of the ore from the waste. At BCL, management of the resource starts with an effective orebody model for planning, scheduling and ore:waste prediction. Ore production from each mining location is reconciled with concentrator tonnage and grade, and the reconciled grades are compared with the planning orebody model to highlight any Differences.

Jan 1, 1986

By Ranklin W. J

The mechanism and rate-limiting step of carbonaceous reduction of zinc from slags was investigated in the laboratory. Disks of graphite were rotated in ZnO-containing slags at various speeds for fixed periods at 1250 to 1325¦C. The mass loss was used as a measure of the amount of ZnO reduced. Application of the Levich equation indicated that at rotation speeds at which it is valid, the reduction was chemically controlled with an activation energy of 27 kcal/mol. At zero rotation speed the reduction of ZnO by carbon appeared to be slag-phase mass transfer controlled with an activation energy of 38 kcal/mol. An increase in the FeO content of the slag increased the rate of reduction while an increase in sulphur content decreased the rate of reduction. When FeO was present in the slag, reduction appeared to occur by a combination of indirect reduction of ZnO by carbon and by reduction by FeO with reduction of Fe203 back to FeO by carbon. The effect of sulphur was consistent with a surface blockage mechanism due to the surface active nature of sulphur in slags.

Jan 1, 1993

By Seneviratne SP

The excessive displacement of the seam floor in headings (i.e. roadways) called 'floor-heave' is often experienced in the underground mines of the Southern Coalfield of New South Wales. Apart from interfering with the mining operations, the phenomenon could be detrimental to the stability of the pillars left for support leading to an unpredictable increase in the subsidence of the overlying strata. The latter could pose a serious problem, particularly in the design of partial extraction layouts of mining for areas where subsidence is to be controlled. The susceptibility of the floor of different rock materials and thicknesses in a given `panel and pillar' partial extraction geometry was examined by two- dimensional Finite Element Modelling of the displacements, stresses and failure zones around the excavations. The modelling, assuming elastic behaviour of the materials, indicated that the maximum vertical displacements of the floor increased substantially as the Young's Modulus of the material decreased to less than 7GPa and the thickness of the layer increased. The results also discount the possibility of a properly designed panel and pillar geometry in the Southern Coalfield of New South Wales being unable to adequately control surface subsidence through the pillar, or its core independently of the yielded ribs, penetrating the floor.

Jan 1, 1992

By G Harbort, T Georgiev, M Phillips

Phu Bia Mining Ltd, a subsidiary of Pan Australian Resources Ltd owns and operates the Phu Kham copper concentrator located in the Xaysomboun District, Lao PeopleÆs Democratic Republic. Construction and commissioning of the 12 Mt/a copper concentrator and associated facilities was undertaken by Ausenco Ltd and handed over to Phu Bia Mining Ltd in April, 2008. The first copper concentrate was produced in April 2008 and the ship carrying the first shipment of copper concentrate set sail 27 July 2008. Nameplate mill throughput was reached in August, 2008 when 1 020 000 dmt of ore was treated in the milling and flotation circuit. The Cu-Au mineralisation is contained in skarn and stockwork mineralisation and is interpreted as a distal expression of a conventional porphyry copper-gold system. Copper mineralisation is principally in the form of chalcopyrite with lesser bornite. Gold occurs as small grains, typically associated with copper minerals. In the upper portions of the orebody, oxidation and water table movements have resulted in near surface leaching of the copper and below the leached zone, supergene enrichment resulted in chalcocite mineralisation. The circuit operates with a semi-autogenous grinding (SAG) û ball mill circuit, feeding a bank of OK200 rougher cells. Rougher concentrate is reground in an IsaMill prior to entering a cleaner circuit consisting of three stages of cleaning and one stage of cleaner scavenging. The concentrate typically assaying 24 per cent Cu and 6 - 7 g/t Au is hauled for over 1000 km across the border to the Port of Sriracha in Thailand, and stocked in sheds at the wharf from which it is shipped to various Asian smelters. This paper discusses the successful commissioning and ramp up to design tonnage and metallurgical performance. In addition, a program to optimise both the comminution and flotation circuit is detailed with reference to grinding efficiency, flotation residence time and size by size mineral recovery.

Jan 1, 2009

By Brechtel C. E

Providing adequate airflow to effectively dilute and remove diesel pollutants in large mine working headings is a little researched area. A simulated diesel mucking operation was carried out in the Exxon Colony Pilot Mine in Colorado to establish expected levels of diesel pollutants in dead-ended working headings. This heading was nominally 15.3 m (50-ft) wide by 9.2 m (30-ft) high. Two face ventilation systems were tested using sulfur hexafluoride tracer gas to represent the diesel pollutants. The results of these tests showed that conventional face ventilation systems operating at high flow rates could adequately ventilate diesel equipment in the 447-522 kW (600-700 hp) range, even in a dead heading 91.4 m (300 ft) in length.

Jan 1, 1988

This paper looks at the problems associated with surface settlements and other subsidence effects from the underground extraction of coal in relation to consent applications under the Resource Management Act. The main features of subsidence are examined with respect to identifying the adverse effects as defined under the RMA. Particular attention is paid to sites where little or no data is available as in the case of greenfield sites or at mines where new or different mining methods are being introduced. In these situations it is not possible to make accurate predictions of settlements or strains and therefore other factors need to be considered. The long term effects which might occur post mining are examined in relation to mitigation and management options.

Jan 1, 2003

By Morland R

In the course of an exploration program aimed at increasing Pasminco Mining's ore reserves, an electromagnetic survey down one of the underground drillholes at the North Mine, Broken Hill, recorded a broad and persistent response. This paper demonstrates that the anomaly was not due to any geological feature, but rather was caused by 'self-response' of the sensing probe. The observed results are due to the surveyed hole lying within a resistive environment and having distinct, but not unusual, changes in dip.This phenomenon has not been widely reported and we believe that there are likely to be similar cases in company records where very genuine looking responses are due to self-response rather than sulphides. These false anomalies can be recognised by correlating the observed data with the calculated down-hole component of the transmitting loop's primary field.

Jan 1, 1994

By Caelli T, Robey M

Most research into planning of open pit mines has been based on evaluation of volume-element block models in terms of their net present value. The major issues revolve around two interdependent problems the optimum ultimate pit and time-based scheduling. Despite feedback between the two problems, they are usually treated as separate tasks.The ultimate open pit is defined by the removal of whole blocks so that their net present value is maximised. This gives planners an estimate of the total worth of the venture in present terms, and is crucial to obtaining funding. All cost and profit values are assumed to be static throughout the mine life, and the only physical constraint usually taken into account is that of safe, average, wall slopes, which must be approximated by the removal of whole blocks. Modelling of any further constraints (for example, access roads and true wall slopes) is usually achieved by adding them to the optimal pit by hand. Typically this degrades the model by between five and 20 per cent of its value - which then brings into question whether it is still the true optimum.This paper reviews the dominant methods in use for this first task the ultimate open-pit planning problem. Some new optimisations are given, and the algorithms are examined in terms of their efficiency and accuracy. Finally, suggestions are made for improvement of model accuracy and eventual expansion into solutions of the more complete dual problem - that of simultaneously finding the optimum ultimate pits and dynamic schedules for the venture.

Jan 1, 1996

By S Wotherspoon

At Kalgoorlie Consolidated Gold MineÆs (KCGMÆs) Fimiston Operations, located on the periphery of Kalgoorlie Boulder in Western Australia, roughly 7.5 million tonnes of rock are broken each month for the extraction of gold. With the close proximity of neighbours to the mining operations in the Chaffers Cut Back, special blasting techniques and tools were employed by KCGM to manage the blast induced vibrations and noise in this area. The i-konTM initiation system coupled with OricaÆs complementary modelling and analysis tools offered the complete blast management package. With these tools KCGM management and Orica Mining Services commenced an investigation into the benefits of electronic initiation. Prior to the commencement of electronic blasting, initial modelling was conducted to examine the vibration time waveforms and their frequency content, as these were expected to have an impact on vibration interaction with structures such as large buildings and urban dwellings. This work looked at results measured for a previous conventionally (pyrotechnic) initiated blast in the area and compared it to the results obtained when the blast was modelled with electronic initiation and faster timings. The predicted peak particle velocity (PPV) and structural vibration factor (SVF) were calculated. From the results it was concluded that the investigation into using i-konTM electronic initiation system and SHOTPlus«-i blast design software had some real potential to improve blast vibration management on the cut back. The use of the electronic initiation system and complementary software allows intricate timing designs to be accurately placed into blasts. The system has a number of working modes that allow either the precise design timings to be logged automatically into each detonator or to be manually logged where a variation from the design exists. Where such variations from the design occur, the electronic system permits the actual timings used to be uploaded back into the design file. This allows both design and real actual timings to be stored for future analysis or reference.

Jan 1, 2004

By G W. Scott, R C. Johnson

Hypogene alteration zones have been described as a precursor to high-grade haematite deposits in Australia, Brazil and elsewhere. This alteration is described as being below or distal and is typically magnetite-carbonate-silicates reflecting Mg - Fe metasomatism. This paper describes, without genetic implication, the mineral zonation and possible structural control on mineralogic variation within the Tilden Mine, a concentrating grade haematite deposit in Michigan, USA. In contrast to the high-grade deposits, these variations are not peripheral to the orebodies but are the ore. The deposit occurs within the Negaunee Iron Formation, along the southern margin of the Paleoproterozoic Marquette Range Supergroup basin. The regional structure is a fault-bounded west plunging syncline within the crustal scale Great Lakes Tectonic Zone, which forms the boundary between Archean granite-greenstone and gneissic terranes. Local structure consists of second-order anticlines and synclines with variable northwest and southwest plunges. The interaction of sedimentation and diagenesis within growth fault controlled basins, along with a possible metamorphic and/or hydrothermal overprint has resulted in a complex series of ore types. For modelling purposes, the deposit is divided into geologic domains based on both lithology and metallurgical response in the laboratory and in the plant. Mineralogic variation is recognised within individual mineral grains; at blast pattern (10 - 15 m) and development drill hole (100 m) scales.

Jan 1, 2007

By G Solly, S Parsons, P Leevers, S Ni

Hematite ore has been mined in the Southern Middleback Ranges as blast furnace feed for the steelworks at Whyalla, by what was then BHP, since 1991. With the floating of BHP Integrated Steel as OneSteel in 2001 and the subsequent loss of key mining personnel, breakdowns in grade control methods and procedures occurred. These were compounded by changes in orebody characteristics and grade distribution leading to poor reserve recovery and poor grade control, both which resulted in loss of control of ore specification and severe deviation from the mining schedule. As a result, a total review of grade control, mining method and scheduling procedures was undertaken as well as a review of contractor quality assurance. It was found that sampling methods were poor and unrepresentative, grade control blocking processes were outdated and did not reflect the geology of the deposit, the ore mining method was outdated and did not respect the geometry of the orebody, reconciliation methods were being completed globally and were not reflective of individual areas of the deposit, and that deviations from the mine plan were occurring due to access to high-grade areas outside the schedule in order to bring stockpiles back on grade. Based on these findings, updated sample splitter systems were fitted to drill hole rigs, double bench sampling was implemented (2 + 4 m samples as opposed to 1 + 8 m sample) and a three-dimensional cellular grade control system introduced to better reflect the geology and orientation of the deposit. At the same time ore mining was changed from front end loaders mining on 8 m benches to excavator mining on three lifts on 8 m benches; this aided selectivity and respected the geometry of the orebodies aiding cleaner recovery. Reconciliation is now completed on a blast-by-blast basis, which allows for quick and easy identification of poorly performing areas of the resource model that can then be incorporated back into resource model updates. Regular daily and weekly meetings are also held with emphasis on the mining schedule to ensure no deviation from the schedule in the long term. These improvements have resulted in a lift in reserve recovery both globally and locally associated at the same time with improvement in grade.

Jan 1, 2005