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By Vutukuri VS, Budavari S

During recent years many investigators have suggested large spacing to burden ratios to improve the fragmentation obtained in blasting. In spite of these suggestions, most operators still use a conventional ratio of 1 to 2. From single hole longitudinal charge tests in laboratory, it is shown that burden controls the fragmentation. The burden for obtaining uniform fragmentation is smaller than the burden to obtain maximum breakage. Tests on two or three holes show that a larger spacing to burden ratio can be used for smaller burdens, but it is not possible for the larger burdens chosen to obtain maximum breakage. By using finite element analysis evidence is presented to show the effect of spacing and burden relationship on blasting results.

Jan 1, 1975

By Napier-Munn TJ

The Whiten model of crushers is currently being refined and extended at the JKMRC, with particular reference to cone crushers. This paper describes the model as a predictor of crusher power draw, discusses the application of the model, and considers the relationship between power draw and crusher performance.

Jan 1, 1988

By T Berryman

The Fimiston reserve is being depleted at the rate of one million ounces per year; most of which is processed by the Fimiston plant, with the remainder being stockpiled. As for most other large open cut mines around the world, Fimiston has an excellent dispatch and tracking system. Reconciliation is used to determine how the various models used in mine planning (such as a reserve, budget and schedule models) are tracking against production. It is also used to gauge the performance of grade control estimation against production; however, analysing the results of this can be complicated and, at times, misleading. The reconciliation process involves adjusting the monthly production data to equal the mill reported tonnes and grade, plus the change in stockpiles. This adjusted number is then compared to the grade control reported tonnes and grade, the scheduled model (monthly planning model) tonnes and grade and against budget (Reserve) tonnes and grade. This paper includes explanations of all assumptions made in the reconciliation process, including the end of month closing stocks balance, the application of adjustment factors to the dispatch data to create a new balanced set of production data and the monthly sign off to comply with the Sarbanes-Oxley requirements of the North American owners. The reserve is reconciled by proved and probable classification. This tool is used to assess the robustness of the classification scheme utilised and identify any reconciliation issues as they arise. Within the Fimiston deposit there are still issues that are clouded by the assumptions made concerning the scale of observation, poor data support and the mining of the narrow lode areas of the deposit. The declared ore mined (DOM) number (which is defined in the paper) can be significantly affected by these assumptions, and these need to be clearly stated and understood when looking at the reconciliation data. The DOM tonnes and grade is a good indicator of real mine performance as it adjusts mined tonnes and grade to take into account the milled tonnes and grade each month, and prevents cumulative errors from building up in mine predicted dispatch numbers or end of period stockpiles. This number allows monthly monitoring of the mine to mill performance and allows valid comparisons to be made back to budgets and reserves over a period of time. KCGM uses three month rolling averages to monitor performance against reserve and budget models. This ensures that monthly distortions in the figures due to stockpiling issues or over mining in a particular period do not lead to false conclusions. Reconciliation performance over a longer period (12 - 18 months) is used to adjust reserve models should significant variance be observed. By closely monitoring the reconciliation performance at the Fimiston operation, fine tuning of all aspects of the grade estimation process from reserve through to grade control can be made. This allows the most accurate data to be used when planning from reserve data for the Life of Mine Plan through to grade control data for short-term mill feed.

Jan 1, 2006

By Denby B, Hollands R. Schofield D

Surface mines are in operation worldwide, the vast majority employ large haul trucks for the transfer of material both to the outside world and around the site. The sheer size of these trucks and the operating conditions means there is a high

Jan 1, 1998

Cataclysmic or flood-like release of gas-charged brines, hydrocarbons and slurries accompanied widespread mineralisation of Upper Devonian environments. These are well represented in the Canning and Burdekin Basins of Western Australia and Queensland respectively.The Burdekin Basin provides particularly instructive vein structural sequences. These fall into organic residue to carbonate paragenetic sequences which are known elsewhere to record progressive decarboxylation. Fibrous veins indicate overpressure in fractures with organic residues, acids and gas derivatives driven to overlying groundwater flows. This combination of large flow rates and potent organic mineralisers led to extensive arsenical rare-metal mineralisation which is similar to that concentrated in Upper Devonian extinction horizons of the Canning Basin. Organic-residue mineralisation appears concentrated by certain hvdrostructures and targeted upon particular species. These controls need to be understood to guide modern management stragegies for mineralised organic and nitrogenous wastes.

Jan 1, 1990

During the last 12 years the dominant theme at Mount Isa has been production expansion. Production rate of 3,200 tons per mine day in 1953 increased to 11,000 tons per mine day in 1960, completing the first stage of the programme. The second stage is still in progress. It is planned to increase production of lead and copper ores to 19,500 tons per mine day in 1968.Current mine workings comprise an area 2 miles long and 1/2 mile wide, the deepest production level being 2,000 ft below surface. During the next 10 years it is anticipated that mining will be carried out to a depthof 3,200 ft below the surface. The rapid extension of the mine has necessitated frequent re-appraisals and modifications to the primary ventilation system, and a system with considerable in-built flexibility has gradually evolved. Since 1953, volume circulation has increased eight-fold to approximately 2,400,000 c.f.m.To suit various mine operating requirements, a combined pressure-exhaust system of ventilation was adopted.The usefulness of this system is at a maximum when the fans installed permit ready changes in the location of the boundary between adjacent spheres of fan influence.Air flow through openings to the surface can be controlled or used as required. This feature is considered necessary for a mine where underground workings are comparatively shallow and caving to the surface willoccur.A major heat problem exists due to climate conditions, high geothermic gradient (one degree Fahrenheit in 95 ft), and oxidation in leached and brecciated areas.Because of this, quantities of air far in excess of the minimum requirements for dust removal are required to ensure satisfactory environmental conditions. In assessing fan pressure, consideration was given to 1. the mine resistance, and the requirement for pressure differential capability,2. the pressure requirement for deeper mining, with due allowance for booster fan use where appropriate,and3. the desire to avoid fan operation at pressure duties above the region of peak fan efficiency.The latter feature provides a safety margin between maximum operating pressure and the stall point of the fan.

Jan 1, 1967

By Gillies A. D S

Replies to a comprehensive questionnaire on mine water resource management systems (WRMS), which were distributed to a selection of Australian mining operations in 1991, are analysed. Although the replies cannot be considered fully representative of the industry, they do provide a good qualitative indication of water resource management in the industry at that time.Within Australia's largely arid land mass, a majority of mines nonnally need to conserve water, a few need to dispose of water and a number face a seasonally varying position. An assessment of the importance of WRMS compared with management of ore extraction and processing is given. A risk assessment of failure is given; there is more acceptance of WRMS failure in the mine compared with the mill. An assessment is made of considerations in WRMS design. Managements are generally pro-active in the design of WRMS and in the setting of perfonnance standards. The operational characteristics of mine systems are examined in detail.Companies generally do not appear to allocate sufficient resources for the collection of basic WRMS monitoring data and knowledge of the water budget to efficiently manage the system. This indicates scope for considerable cost savings in most mines.

Jan 1, 1995

By Borsaru M, Wylie AW

A neutron irradiation technique has been developed which is suitable for the determinat- ion of the iron and aluminium content of iron ore fines (-6 mm particle size) on a moving rubber conveyor belt. The determination of iron entails measure- ment with a NaI(Tl) gamma ray detector of the characteristic prompt gamma rays (7.64 MeV) due to thermal neutron capture in iron, while the determination of aluminium is based on thermal neutron activation analysis. For the latter a second detector must be placed down- stream to monitor the 1.78 MeV gamma radiation emitted after activation of aluminium. Although conveyor speed has no effect on the Fe measurement, it has an adverse influence on the aluminium signal, and the belt speed should not exceed 0.1 m/s if good accuracy is required. Static trials on a 460 mm rubber conveyor belt with constant ore geometry indicate that for iron an accuracy of ¦ 1.2% Fe (2a) can be achieved for crushed run-of-mine ore at

Jan 1, 1978

By Bratt G. C, Horsham T. R, Langlois D. R

Mercury is precipitated from weakly acidic sulphuric acid plant waste liquor at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited. Factors determining the choice of process and reagent, as well as details of process development including scale- up, and the time scale of implementation are outlined. The plant is designed for a maximum flow of 120 m3/h.of liquor containing mercury and saturated with sulphur dioxide. Mercury is precipitated by fluidised beds of aluminium pellets contained in lead columns. Liquor is then clarified with plate and frame presses. Experimental work on the mercury precip- itation reaction was conducted in three phases involving a scale-up of 100 times in equipment size. Extensive pilot filtration work was carried out on a 1 m2 press. Scale-up of 120 times was required for specification of plant filters. The basis of scale-up is outlined.

Jan 1, 1977

In order to satisfy environmental and mine operational requirements it is becoming increasingly important to minimise ground blast vibrations at certain locations. These locations are often in soil or on large resonant structures such as grain silos, highway bridges or even the walls of an open pit. A soil monitoring exercise was carried out to evaluate the common practice of coupling vibration detectors to the ground using spikes. At a series of locations in an operating quarry the spiked array response to single blastholes was compared with that of an accelerometer array attached to a calibrated embedded mount. The results clearly showed that the spiked arrays over-estimated the true ground vibration by 46.5 per cent on average, with a maximum observed error of 99.2 per cent. These errors are considered too large for compliance monitoring where accurate vibration levels are required for comparison with prescribed limits. Although spike coupling is convenient, its use for compliance monitoring should be viewed with caution. Unfortunately, however, many manufacturers supply their detectors as spiked arrays. A structural monitoring exercise was also carried out to evaluate the vibration response of a grain silo, highway bridge and a pit wall to the initiation of single blastholes. In this case accelerometers and standard geophones were firmly attached to the bridge which resonated at low frequencies. The results clearly show that, due to their limited low-frequency response, the geophones typically measured only half the true vibration level as measured by the accelerometers.

Jan 1, 1995

Incompetent ore and country rock have caused stability problems in longhole open stopes. Fully grouted pre-placed cablebolts have reduced these by preventing ground relax- ation and joint dilation to maintain a self supporting rock structure. Larger atope spans can now be opened with the same or smaller pillar. Mining methods are expected to become less dependent on original ground conditions. Effect of spacing, orientation and stress distribution along the cablebolt is not fully understood at this stage and requires more Observation.

Jan 1, 1977

This paper will be a discussion of the geological exploration and drilling carried out on the Mt Davy Block, Greymouth Coalfield. A brief summary of the geology of the Greymouth Coalfield will be given to put the Mt Davy Block into perspective.

Jan 1, 1979

The microstructures exhibited by ilmenite in its association with other oxide minerals have been the subject of a number of papers, the most comprehensive of which is that by Ramdohr. The following observations in some degree extend his conclusions. They are based upon a study of about sixty specimens of "massive" ilmenite and titaniferous ores from a number of wIdely 'scattered Australian localities. Specimens of this character proved much rarer than was expected. The collection was gathered together through the generous aid of the University Geological Departments, Geological Surveys, and Natural History Museums of the several States of the Commonwealth, all of which contributed such specimens of local origin, as they possessed. Special thanks are due to Dr. E. S. Simpson, of Western Australia, who made available several highly interesting specimens, together with his...

Jan 1, 1938

By E Y. Baafi

Artisanal and small-scale gold mining (ASSM) offers lucrative employment opportunities to the locals of most developing countries. The major drawback of ASSM is its adverse impacts on the environment resulting from improper mining and processing techniques. Papua New Guinea (PNG) has very active ASSM activities. The artisanal and small-scale gold mining in PNG provide employment at local and national levels and the sector is an important source for inflow of foreign exchange into rural communities. However, small-scale mining activities are associated with sensitive health and environmental issues. The process of recovering gold by retorting and heating the amalgam over an open fire is a dangerous health practice. This paper discusses artisanal and small-scale gold mining operations in PNG and their impacts on the local environment.

Jan 1, 2008

By Adhikari G. R, Raju N. M

The breaking of rock by explosives occurs so rapidly that the details of the phenomenon cannot he observed by the unaided eye. High resolution cameras and VCRs offer a means of slowing down the blasting action. A high resolution super video camera with digital zoom and a variable shutter speed was imported and used for the first time in India as a tool for blast optimisation studies at Malanjkhand Copper Project. Slow motion play-back revealed that the gases vented out through the fissures. The crest moved prior to the lower portion of the bench when initiated with detonating cord. The delay timing between the rows was not enough to provide sufficient relief and rock movement. This inadequate delay timing resulted in flyrock from the back rows. Stemming ejection was observed from practically all the holes. The muck profile was not satisfactory. A trial was carried out using 450 ms in hole delays and 25 nis surface delays. The front row holes were drilled based on the observations made from the laser profiling survey system. The video of the monitored blast showed that the rock started moving prior to the stemming ejection. It could be clearly seen that the entire block was completely initiated through the surface delays before the onset of the burden movement, thus eliminating any chance of misfires. Viewing blasts in high quality slow motion was useful to arrive at modified design parameters, resulting in uniform fragment size distribution and controlled rock movement.

Jan 1, 1995

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

By M D. Raine, J K. Bartlett, S C. Dominy

The Bendigo Goldfield is located in the state of Victoria, Australia, and is one of a number of fields that make up the Central Victorian Goldfield. Since 1993, Bendigo Mining NL has been carrying out an extensive re-evaluation of the goldfield and is currently well advanced in developing an underground mine. The sediment-hosted auriferous quartz reefs are structurally complex and closely associated with anticlinal axes and reverse faulting. The gold within the quartz reefs is characterised by both its coarse nature (100 up to >5000 ¦m) and its erratic distribution; as a result, the Bendigo Goldfield is classed as an extreme nugget effect system. This characteristic ensures that the Bendigo mineralisation is very challenging to sample and evaluate. In this case, diamond drilling is a good measure of structure and geological continuity, but a poor measure of grade and grade distribution. Drilling, combined with on-reef development, bulk sampling and detailed geological studies are required for resource evaluation. For grade control a balance has to be sought between sample representativness, cost, turn around time and practicality. Extreme nugget effect deposits like Bendigo, require the use of bulk samples in order to be representative. However, the cost and turn around time is significant. As a result, a micro-bulk sampling system has been introduced that attempts to overcome these problems by providing a fast, practical method that can define ore from waste. Bulk sampling and on-vein development are still necessary for resource and reserve estimation.

Jan 1, 2003

By Gomm SA

The Mount Tom Price Concentrator, which contains a heavy medium cyclone plant for beneficiation of the -6+0.5mm fraction of low grade iron ore, is described. Testwork was carried out on an opportune basis over a period exceeding twelve months, to evaluate the separation performance of the heavy medium cyclones. Plastic density tracers were used and ore samples were taken and analysed. The effect of operating medium specific gravity (S.G.) on the separation parameters, the iron grade of the sinks product, and the mass and iron recoveries were investigated. Also examined were the differences in perform- ance between particles of different size. The implications of the findings for plant oper- ation are discussed.

Jan 1, 1987

Exploration risk increases with time, due to a general decrease in prospectivity as the more accessible deposits are found, and be- cause of rising costs and demands due to an improving standard of living. Risk is separated into financial risk, which increases sharply at the development stage, and the risk of failure which is at its peak at the outset of exploration. Risk is also divided into internal and external factors; some of the latter cannot be offset, viz. the systematic overall risk for any enterprise. The recently emergent risk embodied in withdrawal of large areas from exploration access is discussed. An appeal is made for objective multiple land-use policies to be applied so that land remains available at reasonable cost and with appropriate environ- mental safeguard conditions. Risks specific to gold exploration are discussed. As gold now accounts for over 50% of all mineral exploration, and most other metals are depressed, any sharp decline in gold will have grave effects on the ex- ploration industry. Gold exploration will become more difficult and expensive in about five years, after most of the readily accessible deposits in Australia are found. Government's role is important in pro- viding stability and basic data at reasonable cost. Exploration for specific minerals or of particular areas could be stimulated by extending the 150%.tax deductibility of R & D to aspects of exploration of strategic im- portance, particularly in the event of a downturn. Exploration is classic scientific research, at least through to the proving Stages.

Jan 1, 1987

Access roads for haulage, construction or maintenance purposes are discussed with particular attention being given to the un- sealed "all weather" form of construction for Off-Highway applications. The service conditions experienced by the surfaces used in these roads is examined. These conditions are discussed in terms of the conventional engineering properties used for natural gravel material selection. Experience gained during the construction of a pipeline access track is used to illustratE material selection guidelines based on geological input and an understanding of good construction practices. TMITDnIll IrTT Ohl In many Australian situations off-highway haulage by wheel or track supported vehicles is carried on unsealed, gravel roads. Although the unsealed gravel road is the back-bone of the rural road network in Australia, in general, traffic loadings are relatively low compared to the off-highway unsealed haulage road. The cost of the haulage/access road construction component is one important factor in project planning which needs careful consideration. It is no longer acceptable that the initial rough exploration track be gradually upgraded so that it will eventually carry construction and maintenance traffic safely and efficiently. Fatal accidents and

Jan 1, 1982