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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 Kurihara K, Tanimoto C

Construction and mining sites are often subject to unexpected flooding and extensive delays may occur in locating and installing emergency pumps. This particularly applies to sites located in remote areas. A simple and effective pump, called an air-lift pump, can be built from the equipment available at the working site. The basic req- uirements are a compressed air supply, air hose and conventional water pipes. The air-lift pump is comparatively in- efficient but approximately 35 per cent of the available compressed air power at the site can be applied to pumping. Suprisingly high liquid discharge rates may be obtained in suitable applications. The theoretical and practical consider- ations of the air-lift pump are evaluated and a suggested procedure for the emergency design and construction is outlined. INTRODUCTION. Sudden inundations of water into mine and development excavations require the immediate removal of the water if extensive and often irrepairable damage is to be avoided. Pumps installed in shafts or tunnels may become un- servicable due to being totally submerged during the flooding. The emphasis is on rapid

Jan 1, 1976

By Veal FL

Technological changes in Portland cement manufacturing during past years have reflected changes in the economics and availability of various types of fuel such as coal, fuel oil and natural gas. The industry consumes a sig- nificant quantity of both thermal and electric- al energy. The nature of the process and its chemical constraints does however permit the use of comparatively low grade fuels such as high ash coal and high sulphur oil. In striving for increased daily kiln outputs and conservation of energy, there is a worldwide trend towards the use of dry process plants. Wet process kilns of about 2 500 tonnes per day assume massive component sizes which present difficulties in manufacture, and transport to plant sites. Large capacity dry process units in excess of 8 000 tonnes per day are now in operation using precalcination techniques in which part of the fuel is introduced in the static preheater section ahead of the kiln while the balance is added to the kiln in a conventional manner. This technique has virtually doubled the potential output of any given single kiln.

Jan 1, 1976

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 Arnold J. J

The design of a coal preparation plant using bore core data cannot be discussed without some reference to the wider considerations of design. A thorough knowledge of coal preparation processes and processors as well as ancillary equipment is essential if the coal properties determined from bore cores, are to be fully utilised. Whilst generalised information of processes is available from a wide range of publications and equipment suppliers for the intending plant designer, local operational experience must be taken into account where there are similarities. However it would be wrong to assume that satisfactory plant design can be achieved merely be repeating previous design parameters. A detailed examination of bore cores used in conjunction with well proven design 'criteria will identify important differences in design parameters without which efficient and economic plant/sectional sizing cannot be achieved.

Jan 1, 1977

By Singleton T

Increasing world competition puts pressure on sales volumes and prices. This in turn reduces potential profit margins. This in turn increases the focus on costs.Increasing demands on quality and service puts pressure on delivery performance - the right product at the right time. This in turn reduces the scope for errors and delays - and this in turn increases focus on equipment reliability. In the mining industry, both costs and equipment reliability have one significant thing in common - they are driven substantially by maintenance.

Jan 1, 1998

By J Ranford, A Harris, K Laughton

The Angas Zinc Mine (Angas) is a poly-metallic, underground mine in the Adelaide Hills that has been developed through arguably one of the most volatile financial time periods in living memory. From boom times during the commencement of the project, the global financial crisis (GFC) through the stabilisation of the operating period and then a subdued capital market for the period where mine life extension was targeted, the financial environment has always presented a different set of challenges. Indeed even the Underground Operators’ Conferences that have been held across the span of the project allude to these changes: ‘Boom and Beyond’, Launceston (2008); ‘Safe, Innovative and Sustainable’, Canberra (2011) and ‘Managing the Margin’ in Adelaide (2014).Angas gives a rare opportunity to see the entire life-of-mine of a project and its economic performance within a relatively short time frame. Angas, owned and operated by Terramin Australia Ltd (Terramin), will have undergone resource estimation drill out, feasibility study, permitting, commissioning, operating and completion and rehabilitation all within a period of approximately ten years. A number of sensitivities of the project were tested, particularly in the bankable feasibility study (BFS) stage and the aim of this paper is to identify the factors that impacted the operations profitability the most, whether they were identified preproduction or not. The key sensitivities assessed in the BFS were typical of similar studies, including operating costs, metal recoveries, capital costs, zinc prices, lead prices and exchange rates. The manner in which these sensitivities presented themselves in real life were not as anticipated and modelled in the feasibility study and were also heavily impacted by technical challenges.CITATION:Harris, A, Laughton, K and Ranford, J, 2014. Feasibility to mine completion – the real impacts on project economics, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 99–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Weining L

In-situ experiments were performed in a tunnel built in loess soil with the displace- ment components of the tunnel lining and the acceleration components of the tracks measured during the passing of trains. The measured parameters were then studied by the spectral method. As a result, the dynamic forces of trains was simulated numerically and a deter- ministic dynamic nonlinear analysis was carried out by means of finite element method. The results obtained by two different approaches were in fair coincidence. Results of the study indicate, that the low and medium frequency components of the dynamic train loading would be crucial for the dynamic responses of the tunnel lining and surrounding mass, and their effects would increase with the speed of passing trains within a certain range.

Jan 1, 1987

By Wingham DW

Based upon the previous work of Norman and Loeb, a method, was used, to assess-the comparative wearing properties of ten different alloys being used, or being considered for use, as mill liners and grinding media at Mount Isa. The materials to be tested were obtained in the form of large diameter balls and were run, along with the regular ball charge, in a large ball mill operating-under normal grinding conditions. At selected. intervals, the test balls were removed from the mill, weighed and identified, and their relative wear rates determined.

Jan 1, 1963

Results are presented of the investigation of gas dynamics of the blast furnace process obtained on laboratory models and operating furnaces. Gas residence times were measured using a helium tracer technique developed for the purpose. Residence times were determined in furnaces of 1007 m3 and 1719 m3 and results used in the calculation of the burden parameters and to estimate the distribution of the gas flow along the furnace radius. The effect of tuyere injection of coal dust on gas distribution was also investigated and the advantage of continuous injection compared with intermittent injection is noted. The unevenness of gas distribution across the furnace area is found to correlate well with differences in the size analysis of the iron-bearing component of the burden. The mixing of the gas streams between the neighbouring raceways was studied. It is shown that in the central region of the furnace gases from every tuyere are mixed together, whilst in the peripheral regions mixing is more localised and includes only the sections consisting of five adjacent tuyeres. A solution is proposed to the problem of a theoretical evaluation of the critical gas velocity. A simple relationship between the Reynolds and the Archimedes numbers was obtained from which, after substitution of the burden size data and the gas parameters, it is -possible to evaluate the critical gas velocity. Conclusions include information relating to the optimisation of the gas distribution and views on reducing gas injection at elevated furnace levels.

Jan 1, 1975

By Jaracz K

At the operation of mine winders in deep shafts considerable oscillations of winding ropes may occur due to elasticity of both wind-ing and balance ropes. The amplitudes of longitudinal oscillations may reach + lm at relatively low frequencies, ranging from 0.5 to 2 c/s. These oscillations may be dangereus for the rope and produce several hazards to the winding installation as a whole. They may cause conside-rable instant accelerations on the pulley and dangerous tensions in ro-pe wires. The excessive acceleration may cause the uncontrolled rope slip on the pulley. Several methods of limitation of these accelera-tions were developed, some of them have been already in control system: of electric drive of the winder. The most simple ones are: a/ limita-tion of the rate of change of acceleration and retardation of the win-der /so called "jerk"/ and b/ the proper selection of regulators of the winder control system to get the optimal control. The trouble in solv-ing the problem of rope oscillations is that the dynamic system of the winder is a nonstationaryone owing to changing distance of conveyance from the pulley. Besides, the system is described by the equations with distributed parameters. The brief discussion of the theory and its practical aspects are enclosed as well.

Jan 1, 1985

By Adshead ND, Blake KL, Rotherham JF, Rotherham M, De Jong G

Magnetite deposits with distinctive ¦ actinolite ¦ apatite -bearing gangue and spatially-extensive sodic-calcic wall rock alteration occur in both Proterozoic metamorphic terrains and Mesozoic-Tertiary magmatic arcs. Examples from both settings constitute significant sources of iron ore (e.g. Kiruna, Sweden; El Romeral, Chile) and some host major Cu-Au deposits that have a local association with K-silicate alteration (e.g. Cloncurry district, NW Queensland; Copiapo district, Chile). A growing body of evidence points to a hydrothermal origin for these systems involving high temperature, low S oxidized fluids. The Cloncurry magnetite-Cu-Au deposits are products of the local structurally channelized influx of a specialized high salinity ore fluid into larger-scale alteration systems developed during pluton emplacement at greater depths than those associated with subvolcanic (porphyry) Cu-Au deposits. The geological characteristics of deposits in magmatic arcs are consistent with a similar mode of origin albeit in rather different tectonic settings.

Jan 1, 1995

By P Andrieux

By 1996 ground control-related problems at Brunswick Mine had raised serious concerns regarding the safe and economical extraction of large portions of the reserves. These difficulties were mainly caused by high stress levels in pillars, instabilities resulting from wide spans supported by ageing support elements, and chronic difficulties supplying rock fill from the surface quarry to the underground workings, which resulted in many large voids remaining open for long periods of time. Significant changes have been implemented at the site since 1996, amongst which were a change of mining method, the introduction of paste backfill, the establishment of stress management measures, and the introduction of shotcrete on a large-scale. This paper focuses on the regional ground conditions associated with both the previously used primary-secondary mining method and the newly implemented pyramidal pillarless technique, as well as on some of the stress management measures implemented at the mine.

Jan 1, 2000

By Watson K, Pollard D. M

The electrolytic recovery of metals from solution requires an understanding of the characteristics of the particular system employed, and the current efficiency and morphology of the deposit are influenced by such factors as cell design, metal ion and supporting ion concentration, acid concentration, temperature, impurity levels and cell design. The electrolytic deposition of both cadmium and silver present individual difficulties, and special cell designs are used for each of these metals. It was found that cadmium deposition was plate-like at lower cadmium concentrations, and at higher current densities. The presence of zinc in the electrolyte promoted nodular growth. Current efficiency remained high even at 50C in contrast to published information. Silver deposition morphology was relatively unaffected by changes in silver concentration, pH and current density. Current efficiency was reduced as temperature was increased.

Jan 1, 1989

Sasol Roche Blasting Services (SRBS) has undertaken a process of trialing and evaluating the use of the SMI electronic initiating system with the specific purpose of being able to fully quantify the benefits of the system over a pyrotechnic system. After an initial trial of three shots in mid-2001, it was decided that to fully quantify the system, a complete strip would need to be fired using the system so that any losses due to ramps or end walls would be the same for both scenarios. The results have shown a significant improvement over the use of pyrotechnic initiators in several key areas including percentage cast. Through the use of survey results, the increase in cast and subsequent net improvement in blasting has been quantified. These trials have set out to compare each system in comparable situations to determine the real benefits, if any, of the electronic system over the pyrotechnic one. As the percentage cast is relatively easy to quantify using modern survey techniques, it was decided that this would be the principle method of comparison. However, while the assessment only included survey results, any improvement in fragmentation size and consistency would have flow on effects on reduced running and maintenance costs.

Jan 1, 2003

By Doyle J

The direct method of gas content determin ation developed by McCulloch and Diamond of the U.S.B.M. has been adapted to estimate the gas content of coal seams from slim exploration borecores in the Southern Coalfield. Emphasis has been placed on the measurement of this parameter without the physical destruction of the core which is required for subsequent chemical analysis. In field and laboratory equipment is simple and inexpensive. It enables the determination of lost and desorbed gas from a fresh geological core. Residual gas is not measured but is considered to be relatively low and of no consequence in ventilation considerations. Results to date show good correlation with those obtained from underground face samples. Gas contents from the mined seams varying from 2 m3/tonne to 14 m3/tonne have been measur- ed with this apparatus. Gas desorption characteristics of South Coast coals have been found to closely follow exponential mathematical Models.

Jan 1, 1983

By Just GD, Phillips R

The application of high pressure water jet technology to the drilling of longholes in coal has resulted in the development of a system currently capable of drilling to lengths greater than 200m. Field tests at the German Creek Mine have demonstrated directional control of the holes within a 0.5m section of the seam. Initial application of the technique at the German Creek operations is for drilling methane drainage holes. These developments, in three stages, result from support by the National Energy Research Development and Demonstration Council

Jan 1, 1991

By A J. Moore

Predictive assessment of surface blast vibration requires the identification and quantification of significant factors, and the summation of their combined effect. Methods available for the prediction of significant factors are described, and examples are given of the combined use of these methods to evaluate alternative proposals.

Jan 1, 1999

By M Titley, E Maidens

Many gold deposits were mineralised by fluids and processes that also altered the host rocks. This alteration may often be a useful visual aid that distinguishes barren, low-grade from high-grade regions in a rock mass. Alteration intensity is commonly used in gold deposits as a visual tool, along with face sampling or grade control support, to define oreblocks and guide excavation in underground and open pit mining. However, alteration is not often used at the resource estimation stage. Mineralised lodes are usually defined by geologists using a ægeo-grade envelopeÆ, where a number of constraints are considered, including an (arbitrary) cut-off grade; the ænaturalÆ grade break between high- and low-grades; and geological features including structural, lithological or alteration continuity. The geo-grade envelope is usually thought to satisfy the requirements of stationarity for grade estimation, and is considered a single domain. This paper examines a modelling technique combining gold grade and alteration, applied to the Wallaby deposit in Western Australia, to imbue a greater level of detail to the grade estimation in a region tested by relatively sparse drilling. This was achieved by utilising the correlation of gold grade and alteration, along with the spatial characteristics of the alteration, when estimating grades within a number of lodes. The alteration-driven estimation was utilised in conjunction with an unfolding approach, and the use of probability estimates, to overcome geometric data constraints. This technique allows greater control and most likely provides a more reliable estimate of the mineable resources than a global grade cut-off when visual control is to be a major vector in grade control.

Jan 1, 2003

The results of the washing of coal are often presented by using Partition Curves. By analogy, it is possible to express the results of screening by using similar partition curves. As in the coal washing processes, this method determines the accuracy of screening and is also suitable for different separations depending on the difference in size distribu- tion. This method compares the effectiveness of two screening operations and forecasts the performances.

Jan 1, 1984