Search Documents

By D. Ouellet, G. Gagnon, B. Simser, V. Falmagne

The mining sequence at Noranda’s Bell- Allard mine calls for two mining fronts retreating toward a central pillar known as the Retreat Zone between pyramids A and C. It is clear from numerical modelling and rock mass characterization that the induced stress level in the pillar will exceed the rock mass capacity. A mining plan was developed including the redimensioning of stopes in the Retreat Zone, additional ground support and instrumentation in order to ensure the safety of the workforce and to maximize ore recovery while minimizing production delays. The mining strategy consists in allowing the rock mass to fracture and fail progressively while maintaining control of the existing openings with the appropriate support. A systematic analysis of rockbursting and caving hazards was conducted for all accesses and stopes in order to plan ground support and instrumentation needs.

Jan 1, 2004

By M. Moys

The use of temperature measurements for unusual applications in the analysis and control of column flotation and milling is discussed. This is followed by a review of some of the authors current research in the application of the discrete element method to the modelling of particulate processes, specifically milling, fluidized beds and chute flow.

Jan 1, 2005

A clear understanding of the meanings of terms is important when discussing a project. Whether it is a submission, an investment study, a feasibility study, an environmental impact statement, an estimate, a tender, a contract, or a close-out.report, the need for all parties involved to understand what is under discussion or what has been written is paramount. The clarity of definition and the level of understanding can affect the outcome of the project. It is vital that all parties know what is wanted, what is expected, and what it will cost. This paper draws attention to some of the problems that beset many projects, clients, project managers and contractors, and it is hoped that its presentation will encourage us to pay more attention to defining what it is that is required. Ultimately we should all be the richer for having defined and understood the requirements at the beginning rather than at the end.

Jan 1, 1990

By Sandip K. Mukherjee

This report presents the results of the economic analysis of several applicable alternatives to increase airflow in four underground coal mines. Pressure-quantity surveys were conducted underground and measurements were also made at the main mine fan(s). The existing ventilation networks were modeled using the modified Penn State ventilation simulator. The applicable alternatives were simulated. Performance data obtained from these simulation runs were utilized to conduct the cost-effectiveness analysis. The costs for each of the alternatives included capital, operating and maintenance costs. These costs were expressed as annual ventilation costs per active section in terms of dollars per elm taking into account the economic life associated with each of the alternatives. The benefits were expressed as increased airflow quantity in the critical sections. A section of this report also deals with comparison of simulator predicted air quantity values against air quantity values measured underground. The computer outputs for each simulation run are presented in Volume II of this report.

Jan 1, 1983

By S G. Walters

The minerals industry is facing a productivity and investment crisis. The ‘Millennium Super Cycle’ from 2003–2011 was an unprecedented period of growth and investment resulting in increased throughput and development of lower grade resources to meet demand. During the boom quantity became more important than quality with throughput the key metric. This was accompanied by a general trend of decreasing feed grades across all commodities that was offset with higher production volumes.Current industry perception is that feed grade depletion is an unavoidable consequence of ore deposit geology and mass mining technologies for increasingly mature mining operations. In typical crush-grind-float operations value recovery only takes place at ~1–200 micron particle size during flotation, ie 3–4 orders of magnitude size reduction compared to primary feed. For increasingly low-grade deposits the cost of energy and capital intensity required to process and reject low value material at micron scale drives poor productivity. An alternative is to deploy a range of coarse (~10–100 mm) separation and rejection technologies. Grade Engineering® is an integrated approach to coarse rejection that matches a suite of separation technologies to ore specific characteristics and compares the net value of rejecting low value components in current feed streams to existing mine plans.Coarse rejection can be used on size distributions ranging from run-of-mine (ROM) to semi-autogenous grinding (SAG) discharge. Grade Engineering® is based on five rock based ‘levers’ linked to combinations of screening, sensor-based sorting and heavy media separation. These involve exploitation of preferential grade deportment to specific size fractions during breakage: differential blasting to condition grade by size at bench scale; sensor based sorting at truck and conveyor scale; and differential particle density.Grade Engineering® is being developed and implemented by a consortium of over 30 mining companies, equipment suppliers and research organisations. Emerging results from collaborative site activities demonstrate potential for generating significant value, which can reverse the trend of declining productivity due to feed grade depletion.CITATION:Walters, S G, 2017. Driving productivity by increasing feed quality through application of innovative Grade Engineering® technologies, in Proceedings Tenth International Mining Geology Conference 2017, pp 263–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

The extent of regional stratigraphic and structural geological mapping so far carried out in Australia is likely to be greatly overestimated by uncritical inspection of the latest authoritative geological map of the continent-that so ably compiled by the late Sir'T. W. Edgeworth David. Vast areas geologically coloured on this map are in fact known only from the most meagre field data, some of Which even include observations of distant views from which the so-called "geology" has been indicated in' reconnaissance reports.This applies to large areas in Cape York Peninsula; the plateau of Arnhem Land, and its margins except on the west where the Pine Creek mineral belt is better known; to the Desert Basin of Western Australia, practically the whole of the western half of the Northern Territory, much of east-central Western Australia, and northwestern New South Wales. Other vast areas are, more happily perhaps, left blank. It is true that prospecting parties have, at various times and with varying degrees of thoroughness, traversedparts of these little-known regions, often, however, in the search for gold or the.more obvious types of metalliferous mineral deposits and, furthermore, too often without leaving any written account of their examination, or with very sketchy details supplied. Unpublished geological surveys also cover some parts of these regions, but, on the whole, the picture we can draw of the regional deployment of rock masses in Australia is far less full than even David's map, with its obvious blanks, presents to us.Lest the practical mineral seeker among us should be inclined to place too much reliance on the prospecting to which I have referred.as giving him a straight hint of what country to keep out of, we may point to the recent discovery of a major sedimentary basin in the east KimberllilYs on which Dr. Teichert will have more to say. And that there are new metalliferous mineral deposits to be foundin parts of these little-known areas no one can doubt, for, after all, new discoveries are made from time to time in areas so well-known as the Victorian gold-fields. I take it then that regional geological mapping is a necessary concomitant of the further development of Australia's mineral resources-but I am not of the school that places it first on the list of priorities, and furthermore I believe that there can be a royal road to regional mapping-an inspired approach based on knowledge already gained and led to fruition by field surveys in key areas, by which there may be obtained a result giving a significantly close approach to actuality with only a fraction of the work that would be required for detailed field surveys on a systematic basis. I believe that a policy of rapid reconnaissance of such a type should be adhered to, especially in view of present deficiencies in numbers of geologists available for all purposes in Australia. The details that must eventually be sought can, I believe, be filled in later as the whole country becomes more developed and amenable to detailed surveys.

Jan 1, 1950

In the latter half of 1973 a contract was given to Roberts-Holland Joint Venture for the stripping of the southern exhaust airway.The contract was carried out efficiently and relatively cheaply. It was completed 2 months ahead of schedule.The sinking stage and in particular the drilling jumbo proved to be a success and helped produce an above schedule stripping rate.No major problems were encountered with ground conditions or ventilation. A survey of the shaft showed the diameter to be within the set limits of 5·49 m ± 0·15 m.

Jan 1, 1974

By Phillip R. Moyle

A cobalt/manganese occurrence in Clark County, Nevada was the subject of a site-specific mineral investigation by the U.S. Bureau of Mines in 1988-90. The study site is in the northern part of the Million Hills (wilderness) study area which is administered by the Bureau of Land Management. Field work during a period of one week consisted of geological mapping and sampling of workings and outcrops, and geochemical and geophysical surveys conducted on four transects totalling 7,600 ft. Although the concentrations of cobalt (0.1 to 0.5 percent) detected in samples from the fissure zones are within the range of grades associated with world-class economic deposits, the volume of material enriched in cobalt at the study site is insufficient to warrant consideration as a potential resource. Concentrations of manganese, nickel, copper, lead, zinc, barium, and thallium, although anomalous, are too low for economic consideration. At the study site, workings consist of three trenches and nine pits. The exploration history is unknown, and no production is reported.

Jan 1, 1990

By F. S. Karn

Conditions necessary to obtain optimum yield of useful products when coal is rapidly heated to extreme temperatures by laser irradiation were determined by the Bureau of Mines. Product distribution and yield were investigated as functions of several variables. Low-rank coals with high-volatile matter gave highest total gas yields. Medium-rank coals gave the highest yields of H2 and CA and low-rank coals gave highest yields of CO and C02. Macerals gave gases of approximately the same composition, but the total gas yield increased in the order fusinite, micrinite, vitrinite, and exinite. Total gas and C2H2 yields varied inversely with particle size. The addition of nominally inert gases such as Ar, He, N2 increased yields of H2, C2H2, and total gas. Metals such as nickel and platinum had little influence on the rate of coal decomposition. Total gas yield increased with total energy of irradiation, and the ratio of C2H2-CH4 increased with concentration of energy. A study was also made of the irradiation temperature, and a material balance was calculated.

Jan 1, 1970

By Siegfried Arce

Existen muchas herramientas para la gestión de proyectos. Sin embargo, éstos no están en capacidad de realizar análisis de riesgos y evaluar alternativas que consideren incertidumbre. En ese sentido, aparece GoldSim como una herramienta flexible que a través de una plataforma gráfica, posibilita la simulación probabilística y dinámica de sistemas complejos. Asimismo, permite observar las relaciones entre los diferentes elementos, de forma que nos genera transparencia del modelo preparado, por ende,confianza en el modelo y en sus resultados.

Aug 25, 2002

Two outstanding features of the world's young orogenic belts are their very consistently developed suites of volcanic rocks and, it is now recognized, the rather distinctive types of mineralization they contain. Further,it is now known that these volcanic suites exhibit evolutionary patterns, and it is beginning to appear that this evolution in style of igneous activity is accompanied by a parallel evolution in style of mineralization. Specifically,podiform chromite and stratiform pyritic copper ores of Alpine ultramafic/submarine tholeiite association progressively give way to more zincian stratiform ores associated with andesites and dacites, "porphyry copper"deposits developed in quartz dioritic to dacitic plugs, and lead-zinc stratiform ores related to increasingly pyroclastic, rbyodacitic volcanism.This "coupling" is exhibited well in the volcanic arcs - the young orogenic zones-of the SW Pacific which, with tbeir abundance of youthful and commonly unmetamorphosed materials provide an opportunity for investigating, through a petrochemical approach, the possible significance of ores in the elucidation of mechanisms of lava formation. It is suggested as a working hypothesis that in the orogenic (voleanic arc) regime ores are associated with the cale-alkaline rocks because these cale-alkaline rocks are in part generated by exhalative loss, and the ores are among the manifestations of tbat loss.

Jan 1, 1978

By Mohamad Hussein

Low strain dynamic tests are performed to evaluate the structural integrity of driven or cast-in-place concrete piles. This type of testing requires minimal pile preparation, and is simply performed by attaching an accelerometer to the pile head and striking the pile head with a hand held hammer. The measured data is processed by a dedicated system, inspected for wave reflections, and interpreted based on one dimensional wave propagation theory. Piles are normally tested shortly after installation so that problems can be identified early and corrective measures taken before construction of the superstructure. However, evaluation of existing foundations is occasionally required. Often, pile installation records are not available rendering impossible any rational foundation reanalysis. This paper discusses three case histories where low strain dynamic measurements allowed determination of pile lengths and structural integrity under existing structures where pile heads were not accessible.

Jan 1, 1992

By B. W. Gandrud

[This report presents the data of one of a series of investigations of the washability of Alabama coals as indicated by float-and-sink tests mode by the Bureau of Fines at the Southern Experiment Station in cooperation with the University of Alabama and Alabama coal producers. The Klandyke mine, operated by the Blocton Mining Co., is about 1 mile eat of Vest Blocton, Bibb County, Ala., floor the southwestern, extremity of the Cahaba coal field. The Bureau of Mines already has published three reports that deal with the, washability of Cahaba coals - one a washability study of the Clark bed at Marvel4/ one on the tabling of fine coal from the Thompson and Woodstock beds5/, and the third a washability study of the Henry Ellen bed at Acmar6/.]

Jan 1, 1939

By Charles W. Huggins

A study of the high magnification of some inorganic fibers which are found in nature or produced in the laboratory, has been conducted with the electron microscope. This series of electron microqraphs shows the important morphological differences exhibited by potassium-lead silicate, lead-aluminum silicate, chrysotile, wollastonite, silicon nitride, potassium titanate, cobalt chrysotile, magnesio-fluor-richterite, fluor-richterite, refractory oxide fiber, silicon carbide, massive serpentine, and palygorskite. A ribbon or a thin lath 250-2500 A. wide is the structural form of potassium-lead silicate and lead-aluminum silicate. Chrysotile, cobalt chrysotile, and massive serpentine all have a tubular structure and a fairly uniform (150-300 A.) diameter. Wollastonite, potassium titanate, fluor-richterite, and magnesio-richterite crystals have a lath shape, and potassium titanate laths are laminated ribbons. Single fibers of silicon nitride and palygorskite are ribbons, and the silicon nitride sample contains many twins (branching fibers). Palyqorskite fibers are highly flexible and have cross-sectional measurements of 150-300 A. Silicon carbide fibers differ from other fibers because their structure consists of several different forms. The sample used in this study had, predominately, a margarite-type structure. The refractory oxide fiber lost, all its apparent fibrosity after being prepared for electron microscopic examination, and only irregular fragments are visible in the electron micrographs.

Jan 1, 1962

By G. H. Lind

Seven full and partial pillar extraction operations were visited in New South Wales, Australia, in the early parts of 2001. Certain factors unique to these operations have led to the general success of the safe and economic extraction of these coal pillars. Some of these factors attributable to the overall success of these operations are discussed in this paper. In particular, geotechnical mapping, specific legislation pertaining to pillar extraction, mining methods, the role of temporary supports and training are described. It is found that some of these factors have useful attributes which could be used to design a methodology for extraction of underground coal pillars in the Witbank and Highveld coalfields of South Africa.

Jan 1, 2002

By Frederick Laist

AFTER a series of experiments covering a period of about three years, ending from the spring of 19iJ.2 to the spring of 1915, a 2,000-ton leaching plant for the treatment of the accumulated copper concentrator tailing was built and put into operation. During the experimental period, the first step was that of laboratory experiments or beaker leaches. The results on this small scale were so satisfactory that a small operating plant, capable of handling 5 tons of roasted tailing per day, was installed. Again, the results proved satisfactory and an 80­ton plant was built and operated continuously from August until February, 1913. In this plant, full-sized roasting and leaching units were

Jan 8, 1916

By Robert W. Decker

This report presents a survey of published novel coal cutting (mining) concepts and a brief discussion of each one. A preliminary evaluation follows which identifies promising concepts, emphasizing reduced dust generation and economic production potentials. The promising concepts are then studied more deeply and evaluated in more detail with recommendations given for further development action. The concepts recommended for further work include: Roan and Pillar Mining: Deep Cutting Continuous Miner Linear Cutting Rotary Head Miner Longwall Mining: Oscillating Continuous Water Jet Miner Deep Cutting Shearer

Jan 1, 1981

By C. J. Farrow, M. J. Smith

"Bechtel has managed a number of test programs to establish autogenous grinding circuits and size mills for a variety of ores.This paper outlines the procedures whereby bench scale and pilot plant tests are used to select the most efficient circuit to grind the range of ore types likely in the mill feed.Five examples are given. One example traces the development of a pilot plant program; it shows how bench scale Work Indices provide a target for the grinding power requirement of an ore and relates how pilot circuits are changed as a result of interpreting the results from preceding tests. The other four examples relate the interpretation of the test results to provide design data; they illustrate a number of phenomena which have been observed.INTRODUCTIONConventional crushing and grinding circuits can be specified from bench scale test data such as Bond Work Indices. Bond Indices have been correlated to a large number of rod and ball mills and by applying appropriate factors, mills can be sized from the Work Index.For autogenous or semi-autogenous grinding circuits, bench scale tests are not sufficient to be able to specify the circuit and size of the mills for a commercial plant. It is necessary to run a series of pilot plant tests to determine how the ore behaves."

Jan 1, 1982

By Terry P. Medhurst, Stuart A. MacGregor, Peter J. Hatherly

In addition to fractures and joints, compositional factors and bedding influence the strength of clastic sedimentary rocks. Rock mass rating schemes must therefore consider all of these factors. In this paper, a rating scheme for clastic sediments based on geophysical measurements is described. Geo-physical logging allows an approximation of rock com-position to be obtained and an assessment of bedding frequency and laminations. Velocity measurements incorporate the effects of fracturing. The rating requires scores for the intact rock, bedding/cohesion, and defects. These are combined to yield a Geophysical Strata Rating (GSR). Determination of the GSR is objective and repeatable. GSR values are typically between 20 and 80 and can be related to the Coal Mine Roof Rating.

Jan 5, 2007

The problems of using comparatively simple x-ray diffraction equipment for quantitative analysis are examined. Internal standard and direct calibration procedures based upon the measurement of integrated diffraction energy (diffractometer peak area) have been developed for the determination of quartz in Broken Hill dusts. By these methods an accuracy of ± 10 per cent of the true value can be obtained and this can be improved to ±2 1/2 per cent by statistical methods if necessary.Rapid analysis for the components quartz, muscovite, rhodonite, galena, fluorite, sphalerite, calcite, and garnet has been developed by adaptation of direct calibration procedures and use of maximum diffraction energies (diffractometer peak height). Until more is know!) about the pathological effects of multi-component dusts of the Broken Hill type it seems undesirable to fix theIr allowable concentrations in terms of the quartz content.

Jan 1, 1968