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By A Prinsloo, R Tewu

Automatic control of semi-autogenous grinding (SAG) mills has often been considered complex. Recent experiences at Century Zinc (worldÆs second largest open pit zinc mine) refute this. Together with operating knowledge and appropriate control techniques high quality control is achievable. In this application model-based, constraint, and multiple output control were employed. The control was implemented using standard blocks in the plant DCS. The resulting overall control strategy fulfils the operating objectives and controls the mill with minimal operator involvement over 95 per cent of the time. Previous campaigns using expert systems and complex DCS based control have lacked durability. Their fall into disuse is briefly discussed.

Jan 1, 2009

By A. C. Smith

Although only used in a few U.S. longwall mines, bleeder-less ventilation systems can be an effective spontaneous combustion control method in mines having a demonstrated history of spontaneous combustion. To provide insights for the optimization of bleederless ventilation systems for U.S. underground coal mines, a computational fluid dynamics (CFD) study was conducted to model the spontaneous heating in longwall gob areas using a bleederless ventilation system. A single longwall panel with a bleederless ventilation system was simulated, and typical longwall mine ventilation data were used in the simulations. The permeability and porosity profiles for the longwall gob were estimated using a geotechnical model and were used as inputs for the CFD modeling. The effects of gob permeability and resistance of the collapsed entries on the spontaneous heating were studied. The effectiveness of using nitrogen injection to prevent spontaneous heating in the gob was also examined.1

Jan 1, 2008

By W. E. Webb

This report describes a method the Bureau of Mines devised for measuring the dielectric constant and loss tangent of low-loss minerals at microwave frequencies. Determina-tion of these properties makes it possible to predict the effects of using microwave heating in potential mineral processing applications. The method uses a test cell and radio-frequency (RF) impedance analyzer with automated data acquisition and analysis. In this initial phase of microwave heating research, the Bureau measured dielectric constants and loss tangents at frequencies between 100 MHz and 1 GHz. The objective was to establish a reliable data base for use in predicting the effects of microwave heating on minerals. Comparison with previously measured data showed the Bureau's measurement method to be accurate to within ± 3 pct. This report describes the method and discusses the preliminary results of the Bureau's investigations. Typical comparative data are included.

Jan 1, 1986

By Sunil S. Basarkar, Dilip M. Dewaikar, Rajesh H. Gajjar

"A load transfer program AXPILE was developed for simulation of the loadmovement characteristics of socketed piles of the Mumbai reg ion. This program used empirical relationships for ultimate shaft resistance at pile-rock interface recommended by Zhang and Einstein (1998). According to their recommendation, ultimate shaft resistance at pile-rock interface is related to the square-root of uniaxial compressive strength of intact socket material by a parameter C, which ranges from 0.4 for smooth sockets to 0.8 for rough sockets. Results of three instrumented pile load tests were compared with the AXPILE generated results. The comparison of analytical and field estimates of the unit shaft resistance confirm the recommendations of Zhang and Einstein (1998) on the unit side shear parameter c,, which was found to be in the range of 0.35 to 0.67.INTRODUCTIONInstrumented pile load tests were carried out on the test piles at the Bandra-Worli sea link project in Mumbai city of western India. High capacity socketed piles were required to take up loads from the superstructure. Hence, in addition to the available toe resistance, an accurate measurement of the shaft resistance in socket portion was desired. The instrumented load tests incorporated Osterbergcell (0-cell) assisted by strain gauge instrumentation to estimate the shaft resistance mobilization in the socket portion.AXPILE load transfer program was developed for load-movement simulation of socketed piles (Basarkar, 2004). The load transfer algorithm based on Coyle and Reese (1966) was incorporated in this program, which used empirical correlations and functions to account for load transfer in piles through shaft and toe resistance.This paper compares the computed unit shaft resistance from the AXPILE program with the measured values recorded from the instrumented pile load test."

Jan 1, 2005

By R. Hipsley, D. Arbonies, P. Dobak

South Arturo is a “Carlin-type”, breccia-hosted, oxide gold deposit located at the north end of the Carlin Trend. The discovery hole was drilled in July 2005 from mine dumps 1,000 feet south of the Dee open pit. Discovery hole (BD-72) encountered a cumulative 245 feet @ 0.056 opt Au beneath 850 feet of post mineral Tertiary Carlin Formation. Oxidation extends to depths greater than 2,000 feet in the deposit area. The deposit is presently in definition drilling stage with approximately 190,000 feet of drilling completed to date. A resource estimate is in progress. This paper will focus on the discovery and descriptive characteristics of the mineralization.

Jan 1, 2007

By D. Bois, P. Keating, J. Lemieux, M. A. Vallée, M. Allard, R. S. Smith, L. Z. Cheng, M. Chouteau, D. K. Fountain

"As part of a larger research program, a number of MEGATEM airborne electromagnetic (EM) test flights were flown over the Gallen massive sulfide deposit in northwest Québec. A particularity of this test site is that a major part of the ore body was extracted before the MEGATEM survey. Therefore one of the purposes of this study was to verify the ability of the system to detect the remaining massive sulfides below the water in the open pit. The open pit is also surrounded by a metallic fence, and a power line is present in the vicinity. A large part of the case study involved accounting for the impact of infrastructure and acidic water on the survey, which will help in the interpretation of airborne EM responses in complex exploration situations.The Gallen deposit was also previously flown with the INPUT and GEOTEM airborne EM systems before the major exploitation period. A comparison between the results from the different survey results allows estimation of the physical properties of the Gallen deposit, which is a relatively poor conductor.A new method for removing the power line signal shows amplitudes with a smaller residual associated with the emanating fields, and more compact, cleaner responses associated with induced currents. This will make it easier to identify bedrock conductors close to power lines"

Jan 1, 2007

By Lonie W. M

The rapid development of the Australian steel industry over the past twenty years has greatly increased the demand for coking coal from the collieries owned by the Broken Hill Proprietary Co. Ltd. and Australian Iron & Steel Ltd. This in turn has called for an intensive and continuous programme of colliery expansion and new colliery development, along with the reorganization and modernization of existing collieries.This paper presents a general description of the factors involved and the techniques used in planning modern colliery development for the steel industry.PRELIMINARY GEOLOGICAL INVESTIGATIONSIn any colliery development, preliminary geological investigations require a detailed and practical knowledge of the geology and characteristics of the coal-field as a whole. In the early stages of the investigations, probably the most valuable information is obtained from outside the particular area under review, rather than within it, and unless the geology of the coal-field is understood, the projection of the known information into the unknown area cannot be carried out with certainty.Because development of the coal seams from the outcrops has been an apparently simple matter and not subject to the risks involved in deep mine development, the geology of the New South Wales. coal-fields has not received the attention that major mineral resources warrant.Only the most accessible regions of the coal measures have been generally prospected, while the potential areas remain...

Jan 1, 1957

The Aluminum Company of America announced a temporary reduction of the operating rate at its primary aluminum plant at Palestine, TX where it is developing a new process to produce aluminum metal by electrolysis of aluminum chloride, Output will be reduced by half to about 7,500 tons per year while some improvements are being made on the chemical segment of the plant. The modifications were expected to take 3 to 4 years to complete. Alcan Alumininum Ltd., a major U.S. supplier of aluminum, reported declaration of force majeure on aluminum ingot shipment commitments following the shutdown of its primary aluminum plants at Arvida, Isle Maligne, and Beauharnois, Que. The shutdowns, which began early in June, resulted from management and labor differences.

Jan 1, 1979

By A Hanna

Quarries around Auckland have reached or are reaching the ends of their lives, which raises issues about rehabilitation. Significant volumes of 'cleanfill' are generated by the City, particularly during phases of urban renewal and development. Emplacement of the fill in quarries removes the problem of fill disposal and provides an opportunity for restoration of the quarry site.There is a compatibility between quarrying and cleanfilling because at quarries:Truck routes are already established Neighbours are accustomed to the effects and appropriate buffer distances have been established Bringing fill into a site attracts aggregate sales and is very efficient. Fill originates from construction sites and ad-hoc excavations and therefore it is not surprising that sampling has shown the quality to be variable. Both Winstone and the Auckland Regional Council have surveyed undisturbed soils in the region to attempt to determine natural background levels of common contaminant substances. Comparison of these levels with delivered fill shows that a high proportion of delivered materials can be regarded as mildly contaminated. Therefore the term 'cleanfill' is, in the Auckland region at least, a misnomer and the term 'managed fill' has been adopted.Historically and presently the only control on quality of 'cleanfill' has been some visual inspection. This leaves the fill operator open to potential liability for creating a contaminated site. Implementation of controls at WinstoneÆs operations has progressed slowly, over some ten years. This is mainly due to the perception that mobility of contaminants within and out of the landfill will be very limited because of the near-neutral pH and abundance of clay minerals in the fill. The methods of control and results of environmental risk assessments at WinstoneÆs Puketutu Island Quarry will be briefly described.

Jan 1, 2002

By J. Gurland

A method of measuring the degree of contact between grains of 1 phase in multiphase alloys is derived. It is shown that the number and the areas of contacts between grains can be determined by metallographic analysis. Relations between the area of contact, the dihedral angle, and the mean free path of spherical grains are developed. It is often desirable to interpret the mechanical behavior of alloys in terms of structural features observed under the microscope. A quantitative description of microstructures of multi-phase alloys requires consideration of geometrical and topological factors such as the amount, size, and shape of grains and the continuity of the constituent phases. The number and dimensions of grains may be metallographically determined by applying the methods described by Smith and Guttman1 and by Fullman2 in their papers on the measurement of particle size and internal boundaries in opaque bodies. The present work intends to show that the same methods can be used to evaluate some of the parameters of phase continuity; namely, contiguity, number of contacts, and areas of contact of grains of 1 phase. Application of these concepts may be found in such problems as the calculation of electrical conductivity of 2-phase alloys, or the evaluation of the length of fracture path through grains of a brittle phase more or less dispersed in a matrix. I. DEFINITION The following definitions and derivations are based on 2-phase alloys, of which the units of the microstructure are grains. Contiguity is defined as the average fraction of surface area shared by 1 grain of a phase with all neighboring grains of the same phase. In a 2-phase alloy of constituents A and B, the contiguity of phase B is given by: where Cb is the contiguity of phase B aBß is the average area of contact between a grain of phase B and adjacent grains of phase B, aAB is the average area of contact between a grain of phase B and adjacent grains of phase A. The contiguity is a measure of the average degree of contact between grains of phase B in the 2-phase mixture. The ratio varies from 0 to 1 as the distribution of phase B changes from a completely dispersed to a fully agglomerated structure. Smith and Guttman1 have shown that the relative areas of 2 kinds of interfaces in a volume are directly proportional to the number of interfaces of each type intersected by a random line. The lines can be drawn on metallographically prepared surfaces as long as these are random sections through the sample. The contiguity ratio of phase B then becomes: Cb = 2NBB/NAB + 2N BB [2] where: NBB is the number of interfaces between grains of phase B intersected per unit length of random line. Nab is the number of interfaces between grains of phase B and grains of phase A intersected per unit length of random line. The factor 2 arises in Eq. [2] because each interface B-B is associated with 2 grains of B-phase, whereas the interface A-B involves only 1 grain of B-phase. The calculations of contiguity do not require any assumption as to volume fraction, particle size, or particle shape. Fullman2 gives an expression for the determination of the mean free path between particles. The mean free path PB between grains of phase A, i.e., through grains or agglomerates of phase B, may be found from the relationship: PB =2fB/NAB [3] where fB is the volume fraction of phase B. The calculation of the mean free path is independent of grain shape and grain size distribution. The calculation of the number of contacts and of contact area requires assumptions of grain shape, grain size, and contact shape. In the case of uni-

Jan 1, 1959

By Peter Grandone

"INTRODUCTION The injection of water into partly depleted-oil-bearing formations as a means of supplying additional energy to flow oil wells now is recognized by the petroleum industry as an effective method of increasing the recovery of oil. The benefits to be derived from water-flooding oil sands were discovered accidentally more than 4o years ago, when oil producers in the Pennsylvania and western New York fields observed suustantial increases, in oil-production rates when water leaked past corroded casings of old wells into producing sands. This observation prompted some operators purposely to perforate or slit the casings opposite the producing formation in some of their wells to permit water to enter the formation. However, as many operators viewed the practice with skepticism and considered it to be in violation of oil-conservation principles,- systematic water-flooding was not initiated until the Pennsylvania legislature, in 1921, enacted a law authorizing water-flooding of oil sands in that State.Although water-flooding has been practiced in a haphazard manner for more than 25 years in Chautauqua and Montgomery Counties, Kansas, planned or systematic water-flooding in that State had its inception in 1935, when the legislature, following the example of Pennsylvania, also passed a lava/ authorizing water-flooding. The early operations and, to some extent, those still, practiced in the Chautauqua-Montgomery area consisted in raising or perforating the casing to allow water from upper strata to gravitate into underlying oil-producing formations. The extent to which this type of water-flooding affected petroleum production in the old stripper area of eastern Kansas is not known, but it is known to have increased oil production ap¬preciably from many leases.Following enactment of the law permitting water-flooding in Kansas, three operators inaugurated, in that same year, three organized flooding projects in three different counties of the southeastern part of the State. The first organized project on record was that of the York State Oil Co. in the Seeley pool, Greenwood County. On this project, the injection was started on May 15, 1935, into the Bartlesville sandstone at a top depth of 1940 feet."

Jul 1, 1944

By Dennis J. Callaghan

This report is the result of information obtained from a review of related literature, personal inquiry and on-site examination of active surface coal mining operations. Four improved surface coal mine systems are described in detail and evaluated for feasibility, implementation requirements, environmental benefit and costs. Engineering feasibility emphasizes equipment availability, compliance to design requirements, practicality and industry rating. Implementation potential emphasizes immediacy, ease, acceptability and constraints. Special attention was given to environmental responsiveness, both with regard to the solutions to mined-land reclamation problems and to the concurrency of reclamation. Each system description includes a hypothetical model mine with a depreciation schedule, capital summary, estimated annual production costs, sales price computation, production and operating cost summary, and a sensitivity analysis of mine price to stripping ratio. A program plan and time schedule for demonstrating a selected mining system covers site selection criteria, mine data collection, criteria for controlling and budgeting costs and reporting findings. Ten additional mining methods and techniques are briefly described and evaluated. Common reclamation problems are listed and described. Sixteen state reclamation laws and regulations are abstracted. Sixty-nine references are listed in the bibliography.

Jan 1, 1976

By M. B. Fonseca

Risk quantification in grade-tonnage curves is critical for capital investment in mining projects and can be obtained through geostatistical simulations of orebodies. A practical difficulty may arise in multi-element deposits, as the joint modelling of the related attributes using the traditional co-simulation approaches is computationally intensive and may be impractical for use in the industrial environment. This paper presents the construction of risk-integrating grade-tonnage curves for a complex copper deposit in northern Brazil, by jointly simulating its key geochemical attributes of interest: Cu, Fe and K. The joint conditional simulation of these elements is based on Minimum/Maximum Autocorrelation Factors (MAF). MAF is an approach, based on principal components, that spatially decorrelates the variables involved to non-correlated factors. MAF’sspatial decorrelation at any lag distance is the main and critical difference of this approach from the principal component approach attempted in the past. In the MAF approach, the independent factors are individually simulated and back-transformed to the conditional simulations of the correlated deposit attributes that reproduce the cross-correlations of the original variables. Keywords: Joint simulation; mini/max autocorrelation factors; grade-tonnage curves.

Jan 1, 2003

By Gualberto Salas Torrelly

El avance tecnológico en los sistemas de iniciación en voladura abarca desde el sistema convencional (Mecha de Seguridad y Fulminantes hasta el sistema de iniciación electrónica, donde a través de un control de vibraciones se controla la energía liberada en un disparo, optimizando la fragmentación y disminuyendo el daño a las paredes del pit. En ese sentido, el sistema de iniciación con detonadores electrónicos, fija con claridad los conceptos de precisión, flexibilidad y seguridad. Por ello, el presente trabajo señala el uso de detonadores electrónicos por la Sociedad Minera Cerro Verde con la finalidad de evaluar sus resultados en seguridad, precisión, fragmentación, vibraciones, y control de daño a las paredes de la mina. Los resultados fueron óptimos -en tanto mejoró la fragmentación, el proceso de carguío y se incrementó el flujo en chancado primario.

Sep 12, 2005

THE treatment by chlorination of the Mount Morgan Gold Mining Company's ores was first accomplished, early in 1886, by a works having a capacity of 25,000 tons per annum. Shortly afterwards another works was established, capable of dealing with 50,000 tons per annum. The extraction of gold was originally successful and satisfactory, but running expenses were high, averaging £2 19s. 6d. per ton of ore treated. These works were believed to be the largest chlorination pJants in the world at that time. As might have been expected, the mechanical details and chemical process had not been perfected, and, moreover, both works were hurriedly built, and operating expenses were not then considered of such prime importance, as the ore at that time was of very high grade the large quantities of low grade ore since dealt with not being then considered, since the bulk of it was not even known to be in existence.These two works consisted of lock-breakers, high speed rolls, screens, elevators, &c., for crushing; a large number of small handrabbled reverberatory furnaces for roasting; one-ton chlorination barrels and three-ton leaching vats for chlorination.

Jan 1, 1910

By R Zhou, B J. Monaghan, S J Chew, R J. Longbottom, D J. Pinson, H Li, P Zulli, G Zhang, L Lu

Steelmakers are increasingly motivated to use iron ore resources with a wider range of grades and mineral types that were previously considered unsuitable or uneconomical for sintering. In this respect, specific issues, which now require further investigation and understanding, include the sintering of ore types with:- overall higher gangue content- elements that cause problems in the steel manufacturing operations- distinctive sintering performance compared with traditional hematite-rich iron ores. Laboratory-based investigations of the sintering performance and the behaviour of gangue impurities during sintering is an important step towards the successful utilisation of these resources in steelmaking.In terms of laboratory-based sintering investigations, there are two generally accepted experimental scales utilised prior to undertaking industrial-scale trials, which include: bench-scale tablet (compact) testing and pilot-scale pot testing. The former has the advantages of flexibility and more precise control of sintering conditions; but it is difficult to simulate the heterogeneity of a sinter bed. The latter, which is carried out in pots with diameters between 150–500 mm, simulate the commercial sintering process and conditions quite well, but is time-consuming and labour-intensive due to operational complexity. It is therefore desirable to establish a smaller scale pot testing facility that avoids the disadvantages of the normal sintering pot but can provide comparable information.To explore the feasibility of small-scale pot testing, a ‘millipot’ facility was established to examine the sintering performance of iron ores and other non-traditional ferrous materials. The millipot has a diameter of 53 mm and height of 400 mm. The facility has the capability to monitor the sintering temperature at a number of locations (axial, radial) within the sinter bed and to adjust the suction (‘windbox’) pressure. This paper describes the development of the millipot facility and operational procedures, together with initial tests undertaken in order to match its performance with industrial sintering performance.CITATION:Li, H, Zhou, R, Pinson, D J, Zulli, P, Lu, L, Longbottom, R J, Chew, S J, Monaghan, B J and Zhang, G, 2017. A millipot set-up for sintering investigation of iron ores, in Proceedings Iron Ore 2017, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

GENERALTHE coal deposit, where it is being worked, consists of a bed of brown coal varying in thickness from 120 ft. to 200 ft., covered by an overburden of clay, drift, loam, etc., of a thickness of 22 ft. to 40 ft., and averaging 28 ft.The overburden is first entirely removed from the coal, and then the coal is excavated by. large revolving shovels which work at the bottom of the hole or open cut in the coal and deliver it in shovel bucketfuls to the transport system. The shovels owned by the Commission and available for this coal excavation are two Bucyrus steam revolving shovels, one being type 150B, weighing 150 tons, having a 21-cub. yd. bucket, and capable of digging a 47-ft. face; and the other being type 175B, weighing200 tons, having a 31-cub. yd. bucket, and capable of digging a 61-ft. face.In addition to these two steam shovels, the Commission has recently obtained a No. 250 Ruston electric revolving shovel weighing 340 tons, and having a bucket of 10 cub. yd. capacity, and capable of digging a 75-ft. face. When this electric shovel has been erected it will replace the steam shovels on the coal excavation, and the permanent transport system has been designed to take delivery of the coal from its bucket.The duty to be performed by the transport system is to take the coal from the shovels, elevate it out of the open cut, transport it to the screening house, deliver it iuto the hoppers at the top of this building, then to take the coal after it has passed over the screens and distribute the required grades to the power house and to the briquetting plant.

Jan 1, 1924

By R Crookes

Mine to Mill optimisation is not a recently developed concept. It is one which is finally gaining greater acceptance in the Australian Mining Industry, possibly as a consequence of the downturn in markets and certainly made possible by the development of tools and techniques to measure and predict performance of mining equipment and milling plants. Fragment size after blasting has a major bearing on the performance of all aspects of mining and a major influence on the economics of the mine and mill. The process to optimise fragmentation consists of identifying the key factors, measuring their sensitivity through a modelling and trialing program and conducting economic evaluations on the changes on both the mine and mill. Management of the Ernest Henry copper-gold mine in NorthernQueensland, Australia, has espoused the Mine-to-Mill concept and isactively pursuing excellence in blasting to drive down the total cost of mining. Ernest Henry has extremely hard, wet and heavily jointed geological conditions, and had high powder factors and a large percentage of oversize material reporting to the crusher or ROMstockpile. A blasting improvement program was undertaken betweenErnest Henry Mining, Thiess Contractors and Orica Explosives tooptimise the ore size distribution, particularly the oversize component, as a step to reducing production costs. Measures of success included bringing the rock breaker back from double shifts to part-time operation and increasing direct dumping into the crusher from 70 per cent to 92 per cent. Tools and technologies to predict and measure the performance ofindividual blasts are needed before it is possible to optimisefragmentation or the downstream processes. These include suchspecialised Orica Explosives tools as SABREX, POWERSIEVE, andPOWERLINE and commercially available drill monitors. As importantare the more common still and video camera, borehole loggers,measuring tapes, surveying equipment such as face profilers, and ahigh-speed camera if possible. There are many tools which can be applied however it is rarely necessary or possible to use all of them due to time constraints and a point of diminishing returns. The critical point is knowing what the true parameters of the blast were compared to design - only then can the predictive tools be effectively utilised. Stage one of the program has seen gradual improvement as theunderstanding grew and practices have been implemented resulting inreduced bridging in the crusher, geological mapping with respective blast designs and the oversize component under control. This paper is about a process approach which links tools and technology to understand the fragmentation drivers and then to optimising the size distribution.The continuous improvement program continues...

Jan 1, 2000

By G. M. Bond

Reduction of the emissions of greenhouse gases, such as CO,, is currently the subject of extensive research. A novel strategy is put forward here, based on a biomimetic approach providing accelerated deposition into carbonate form for long-term sequestration. It offers the advantages of a process that: does not require concentration of CO, from flue gases; could potentially be used in an on-site scrubber to provide a plant-by-plant solution to reducing CO, emissions; is an environmentally benign procss with an environmentally benign product; and is based on readily available, low-cost reagents (except perhaps the catalyst).

Jan 1, 1999

By Kewal K. Kohli, Thomas Z. Jones

This paper presents a simplified computerized method for the prediction of maximum subsidence and the subsidence profile for the Appalachian Coal Basin using the Hyperbolic Function Profile Method. Several case histories are cited to demonstrate the appropriateness of the predictive method. In addition, sample runs and a detailed listing of the computer program is provided. Other popular subsidence prediction methods are discussed and compared with the Hyperbolic Function Profile Method.

Jan 1, 1986