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Two ends of a longwall face are not only concentrated locations of equipment, but also provide ventilation and access. The roof strata stability here has an important influence on mining coal and safety. Based on field obser- vations in the gateways at Zaozhuang Colliery (Shandong Province) and model tests, the author developed a structural model of the overlying strata at the ends of the longwall face - the arc triangular cantilever plate - to which the elastic theory of plates can be applied. Factors influencing the stability of the cantilever plate and its breaking character- istics are discussed. Requirements and design parameters for supports at face ends are pro- posed, based on these factors.

Jan 1, 1986

South Crofty's ventilation network is large and complex. Of the total exhaust air quantity 40% enters the mine by leakage routes through old workings, this air carries high concentrations of radon gas and results in the mine becoming a classified work place under the Ionising Radiation Regulations 1985. Improvements in the control of the ventilating air and dilution by increased air quantity have reduced the average contamination to aelow-0.2 WL. The major part of the radon originates from ground water inflows and from concentrations of radium within the mine with direct emanation from rock surfaces being negligible. Of 600 kBgs-1 total radon leaving the mine 93% cannot be accounted for from known and accessible sources.

Jan 1, 1988

The control of industrial grinding circuits in Australian concentrators has been practised for many years in one form or another. Some have established simple feedback loops in areas such as fine ore bin feeders (tonnage control), mill pump sump levels (flow control) and water additions (density control). There are also some sophisticated systems which infer circuit product size using complex measurements of mass flaws and water additions in the circuit and attempts are made to control those flaws to produce a constant circuit product size. The inferred size method in Australian concentrators has become firmly entrenched in the last ten years and control techniques involving the use of direct size measurements with reliable on-stream sizers have been Ignored.

Jan 1, 1983

Kalgoorlie Consolidated Gold Mines Pty Ltd (KCGM) is a management company, formed in 1989, to manage the assets and operate the Kalgoorlie joint venture for the owner companies Gold Mines of Kalgoorlie Limited (GMK) and Homestake Gold of Australia Limited (HGAL). Mining is still in progress on the 'Golden Mile' and surrounding areas more than 100 years after Paddy Hannan's discovery adjacent to the active Mt Charlotte mine. From 1893 until 30 June 1995 the Kalgoorlie Goldfields has produced approximately 45 million ounces (-1400 tonnes) of gold from mining and treating about 179 million tonnes of ore. This production equates to about 20 per cent of the total Australian gold production and about one per cent of the world's

Jan 1, 1996

By Grant BPM

The lower levels at the CSA Mine have been developed to mine reserves between theNo.7 level and No.9 level.Work on major excavations for the project began during 1982 with the develop-ment of the crusher chamber, on No.9 level. The brows and walls were pre-dowelled to improve stability before mining by mass blasting techniques.At the same time work commenced on theextension of No.2 Shaft from No.7 level toNo.11 level. The shaft was stripped, using hand held drilling, to a raise bored holeand concrete lined to a diameter of 5.5 metres. Plats were developed at No.8 level, No.9level and the loading station.

Jan 1, 1985

By Anderson J. M, Gillies A. D S, Jones N

There are a number of current theories in relation to methane migration and emission into workings following underground coal mining activity and some controversies do exist. Mining causes changes in the stress regimes in surrounding strata and results in fracturing. Permeability increases and methane flows into workings under a pressure gradient. The effects of stress on permeability depend on the physical properties of the coal and surrounding strata. Methane emission also depends on the original methane content and the proportion which will be liberated. There are several methods for determining in situ methane content and desorption characteristics of coal samples and several methane prediction methods but clearly more research is necessary to achieve an adequate predictive model.

Jan 1, 1992

By R. A. Frith, M D. Goodz

Ore-bearing minerals that are located along microfractures are always susceptible to loss during the breakage and sampling of the material. Further losses occur with on-site sample preparation and splitting prior to laboratory analysis. In these cases solid whole rock channel or core samples should be handled with due care to ensure all fines and loose particles are collected and included in the sample for total chemical analysis.Similarly open hole and reverse circulation drill methods are not usable in areas containing old mine workings, heavily fractured ground or highly degraded/oxidised mineral assemblages. Nor are these methods usable to assess a bulk mineable target where the enriched zones were peripheral to or between old mine cavities.

Jan 1, 1993

By Gao K, Wu C, Xia J, Burdett M

X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques have been adopted in this study, to investigate the structure of carbonaceous materials such as graphite, brown coal char as well as coke, in order to explain their dissolution performance during ironmaking. These materials have been selected for study since they are commonly used recarburizers in the metallurgical industry. It was concluded that the crystal structure in a carbonaceous material can have a significant influence on its dissolution into iron melts. The material with the highest degree of ordering, which is graphite, showed the best dissolution performance. In contrast, the material with the lowest degree of ordering, which is brown coal char, showed the worst dissolution performance.

Jan 1, 1996

Three major and two minor uranium deposits 'have been worked by open out mining since the discovery of ,the Rum Jungle field in 1949. Total production has been about 9679000 tons of uranium ore at 7;39 lb U308/ton and 4029000 tons of copper-uranium ore at 6.27 lb U308/ton and 2.7% Cu, with significant tonnages of base'metal ores. The deposits occur in or near black pyritic slates of the Lower Proterozoic Golden Dyke Formation, near the contact with the under- lying Coomalie Dolomite. The mineralization is probably younger than the grahite complexes in the area, and a structural-stratigraphic control of ore deposition is used as a basis for uranium exploration.\

Jan 1, 1968

By Shrivastava P

The iron orebodies of the Pilbara region are formed by supergene enrichment of banded iron formation and rarely do such processes produce orebodies with uniform grade distrib- utions. The orebodies being mined or developed have to be worked to grade/quality constraints imposed by contractual agreement rather than natural characteristics. Hence it is imperative to use a non-biased ore reserve calculation method. The geostatistical study of a typical iron orebody is presented. Emphasised are the geological characteristics of the orebody manifested as a variable grade distribution of iron and impurities; the determination of variogram model; subsequent uses of the model for computation of ore reserves and kriged lock estimates; computation of dispersion variance and conditional simulation of orebody.

Jan 1, 1977

By M E. Pierce

Recent advances in comminution and heap leach technology have resulted in the development of many large-scale, low-grade open pit mines that coincide with areas of historical underground workings. Twoand three-dimensional numerical modelling has been conducted to assess the interaction between open pit slope stability and remnant underground voids. Most design analyses for open pit slopes assume a two-dimensional problem geometry. This is not the condition encountered in practice ù particularly when remnant underground voids interact with a large-scale open pit slope. Three-dimensional numerical models have been shown to provide a more realistic representation of the interaction between overall open pit slope stability and remnant underground voids.

Jan 1, 2003

In early 1985, Bougainville Copper Limited commissioned an automatic truck despatch system to control its fleet of 44 trucks and 9 shovels. Productivity gains in the past have been the result of increasing equipment size then improving availabilities. The emphasis now is on improving the use of that availability and in particular for trucks, in reducing non-productive truck movement. A batch allocation computer based truck control system had been in operation since 1978, so to achieve the desired improvements it was necessary to move to an automatic dynamic control system. A description of the system installed is given, together with a review of how the project was engineered, the problems encountered and the results achieved to Date.

Jan 1, 1986

By Eri G

Ok ledi Mining Limited underwent a major transition from radio based truck dispatching to computerized dispatching for its equip- ment fleet in October, 1996. Modular Mining's Computerized Dispatch System was selected based on reputation and superior customer support. Modular's dispatch system is a fleet management system that uses computer, data communication and global positioning sys- tem technology to produce automatic, optimized haul truck as- signments. Optimization is achieved by equally distributing trucks to shovels so that truck queuing and shovel idling times are mini- mized. Computer illiterate mine operations personnel had to overcome a rather steep learning curve to use the high technology equipment. fortunately the system was able to be configured to use bitmap

Jan 1, 1997

The Olympic Dam Mining Operation involves the supply of some 2.2 million tonnes per annum of ore feed for the metallurgical plant. To achieve this approximately 9 km of tunnels are developed per year to gain access to the long hole open stopes that supply the majority of the production tonnes.Vast amounts of data are produced in the mining activity from the geology, mine design, scheduling, surveying, shift reporting through to the statistical reporting and analysis of the performance of the mine activities. Care must be taken when obtaining the data to maximise the usefulness of the data to other users so not to impose constraints or additional processes on future users.

Jan 1, 1992

By R Graber, R Johnson

North American steelmaking practices have evolved based on access to iron ore raw materials containing very low phosphorus contents, typically less than 0.025 per cent P. Cleveland-Cliffs managed Tilden iron ore operation produces iron ore pellets exceeding 0.030 per cent P, which by global standards would be considered low phosphorus, but has limited penetration in the North American iron ore market due to phosphorus content. Recently cathodoluminescence microscopy has augmented more standard ore characterisation techniques enhancing our understanding of the genetic history and process mineralogy of TildenÆs complex martite ore. This paper highlights the unique capabilities that cathodoluminescence microscopy provides for phosphorus mineral identification in fine-grained iron ores.

Jan 1, 2005

The purpose of this work is to determine the equilibrium-state of the aqueous-solution which is produced by the leaching processes, including natural weathering of pyrite minerals. The latter can lead to acid-mine-drainage (AMD). The ferric iron species (Fe3+) resulting from bacteria-catalysed oxidation of ferrous iron (Fe2+), in the presence of water and air, is known to bring about steady-dissolution of minerals chalcopyrite (CuFeS2), sphalerite (ZnS), pyrite (FeS2), and so forth. Good-aeration, relatively high-porosity and sufficient bacterial activity tend to promote leaching in waste-rock-dumps. The composition of the aqueous-phase that accumulates in the pore-space (or in open-pits) is of practical interest as it would strongly influence the leaching of both sulfide and non-sulfide minerals. Since the reactions among the various ionic species occur relatively fast, the solution-phase may be regarded as approaching a state of virtual-equilibrium and it is possible to determine by computation the respective concentrations of the many dissolved species. For the Cu-Fe-H-O-S system, these species may include: H+, Fe2+, Fe3+, Cu2+, HSO4-, SO42-, OH-, CuSO4o, H2O, Fe(OH)+, Fe(OH)2+, Fe(OH)2+, Fe2(OH)24+, Fe(SO4)+, Fe(HSO4)+, Fe(HSO4)2+, and Fe(SO4)2-. The aqueous-system which may be constituted from appropriate mole-quantities of H2SO4, FeSO4, Fe2(SO4)3, and CuSO4 is in fact the result of various natural processes (reactions) and due respect must be accorded to the extents of these reactions. The present model computes the equilibrium molalities of the foregoing ionic and neutral aqueous species, using the iterative equilibrium constant method that ensures strict-adherence to charge-balance and elemental molar-balance constraints. The dissolving sulfide-minerals (FeS2, CuFeS2) consume Fe2(SO4)3, H2O, and O2 and yield FeSO4, H2SO4, and CuSO4 while the aqueous-phase tends to become progressively acidic (declining pH) reflecting the gradual increase in the extents of sulfide-dissolution reactions. The equilibrium-state of the solution-phase is computed for specific set of values for the extents of respective reactions. The temperature and pressure of the system are 25¦ C (298.15 K) and 101.325 kPa (1.0 atm), respectively. The mica-like minerals such as the biotite [H2K(Mg,Fe)3Al(SiO4)3] tend to consume much of the H2SO4(aq), with the extracted K+, Mg2+, Fe2+ and Al3+ ionic species accumulating in the solution. The precipitation of the jarosites (potassium, hydronium, or ammonium) contributes to the removal of ferric and ferrous species from the solution-phase. In the present work, the emphasis is on predicting the compositions of the aqueous- and condensed-phases with advancing time or increasing æextent of reactionÆ. The results of such calculations are compared to published data on raw AMD (acid-mine-drainage).

Jan 1, 2008

By S N. Nyoni, K C. Corin, C T. O’Connor

Considering future water scenarios, as influenced by the increasing scarcity of water and the move towards sustainable process engineering etc, the closed water circuit becomes an important point of study in metallurgical operations, such as in milling and flotation. However, a deterrent in the use of recycled process water is often a lack of understanding of the effects of the accumulation of dissolved ions and other process chemicals. Recovery of the valuable minerals may be impacted by the concomitant complex mineral-pulp chemistry interactions. Literature indicates that these interactions are not necessarily antagonistic to process outcomes. Wet milling using steel media results in the dissolution of Fe from the media, the rate of which is dependent, inter alia, on the type of media and the chemical conditions of the aqueous environment in the mill. The pulp-phase interactions of dissolved ions with sulfide minerals may result in significant changes to the chemical conditions in the mill, which may subsequently impact negatively on the flotation recoveries. To understand the effect of these interactions in the context of the processing of sulfide minerals, this study seeks to consider the effect of three factors, viz mineral type – pyrite (Py) and galena (Gn) -, milling media of different compositions – forged steel (FS), 21 per cent high chrome and ceramic media -, and water chemistry, viz, deionised water (DI) and synthetic plant water (SPW). Ceramic media and galena are used for the respective control cases where the milling media and sulfide mineral contribute no Fe species. Using DI as a control case, a high ionic strength case is used to mimic the changes in water chemistry for a closed water circuit. Batch flotation tests are used as a diagnostic tool to determine the effects of these media-water-mineral interactions to investigate correlations between the chemical reactions occurring and chemical species present during the milling process and the ultimate flotation performance.

Aug 24, 2022

Mid-ocean ridges host approximately 65 per cent of about 100 known sites of high-temperature venting and polymetallic sulfide deposits; most of them are located at the East Pacific Rise (EPR), while more diverse mineralisation styles occur at the Mid-Atlantic Rise (MAR). Seafloor hydrothermal activity at the EPR are related to MORB while different substrates, including MORB and ultramafic intrusive rocks, are associated with æblack smokersÆ at the MAR. Depth of hydrothermal activity ranges from 0.7 to 4.3 km. High-temperature vents precipitating Cu-Fe sulfides (chalcopyrite and isocubanite, rare bornite), pyrrhotite, pyrite (¦ marcasite), and sphalerite, and low-temperature edifices precipitating marcasite (with pyrite), sphalerite, barite, andsubordinate chalcopyrite (pyrrhotite and isocubanite are absent) occur in both environments. There are considerable differences in Fe, Zn, Cu, Ag, Au and trace element contents in ores and in theFeS contents in Zn-sulfides in these deposits. Acomparison with anhydrite and sulfide minerals precipitating from modern black smoker fluids sulfide reveals many similarities but also some important differences. Fluids with salinity values above and below that of seawater at 400¦C down to 130 - 170¦C deposited sulfide minerals. Mantle-derived He prevails in fluids trapped by sulfides in EPR 9¦N and 21¦N hydrothermal systems. Hydrothermal fluids in MAR and back-arc systems are richer in radiogenic 4He. The sulfur isotope composition varies in the different hydrothermal fields and within zones of a chimney. EPR sulfides display narrower range of d34S values, while MAR and back-arc sulfides can bedepleted and enriched in the heavier d34S isotope. The most important finding is that fluid temperature, salinity, R/Ra ratios and d34S values ranged more significantly in the polymetallic sulfide deposits than when measured directly on venting fluids. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By P Cameron

Many products and technologies have been developed from outcomes of research projects carried out by the Julius Kruttschnitt Mineral Research Centre (JKMRC). When these products and technologies are applied to the design and optimisation of blasting, comminution and separation, improvements in profitability can be realised. In 1970 Alban Lynch promoted two practical ideas to improve plant operations: Ore and equipment properties can be separated allowing experience with one type of ore or equipment to be transferred to other types of ore and equipment. If this experience was encapsulated in a mathematical model, then these properties could be combined and used to simulate (ie to design and to optimise) complete mineral processing circuits. Many problems associated with scale-up from laboratory to industrial equipment could be eliminated by experimental work on full-scale equipment in the plant. Many JKMRC research projects have focussed on the development of models of unit operations in mineral processing and their application to process simulation. Models of comminution and classification developed at the JKMRC have been used since the early-1980s. Ore characterisation techniques developed to support these models are licensed world wide through JKTech. The application of comminution modelling techniques to blasting, which optimises the process feed size distribution is used in Mine-to-Mill? projects. The advances in the understanding and modelling of froth flotation over recent years have provided the opportunity for integrated ore characterisation and process optimisation from resource to product. JKMRC project outcomes often provide proven opportunities for the mineral industry to improve performance and productivity. JKTech was established in 1986 to commercialise and market the most promising outcomes and thus ensure their continuing availability to the mineral industry. These include: commercial software (JKSimMet, JKSimBlast and JKMetAccount); monographs (Comminution and Blasting); technologies (Mine-to-Mill? and flotation optimisation); and hardware products (JKFrothCam, JKJetLift? and the Mineral Liberation Analyser). This paper summarises these technologies and their benefits.

Jan 1, 2002

The Callie Underground Mine is located in the Tanami Desert 560 km Northwest of Alice Springs in the Northern Territory and is currently operated by Newmont Australia Limited with all mining activities carried out by Henry Walker Eltin. Callie was discovered in the region in 1991 with the box cut portal commenced south of the pit in 1995 and underground ore production commenced in 1998, after completion of the profitable Callie Open Pit. Development is currently occurring at depths of over 700 m with the decline currently below the 640 Reduced Level (RL) level (surface RL of 1400) with production haulage from 600 m below the surface. The combination of auto compression, a moderate geothermal gradient of 2¦C/100 m and diesel heat transfer causes the wet bulb temperature of intake air at the bottom of the mine to be typically 5¦C higher than on the surface. Wet Bulb temperatures can be up 5¦C higher again in active areas under secondary ventilation. During the 2002/2003 wet season many activities in the lower levels of the mine were stopped due to miners experiencing adverse heat related symptoms or the temperatures exceeding the Underground Heat Management Procedure stop job criteria of 32¦C wet bulb. To improve the working environment, combat the heat related illness and improve operational efficiency, a temporary 1.8 MW refrigerated cooling plant consisting of three 600 kW modules were installed underground to provide bulk air cooling for the lower levels of the mine during the 2003/2004 wet season. Several studies have been conducted in relation to future ventilation demands at Callie and all came to the conclusion, that some mine cooling will be necessary for Callie to meet the high production and development demands. This paper will describe the ventilation network at the Callie Underground operation focusing on the installation, operation and effectiveness of the temporary underground refrigeration plant.

Jan 1, 2005