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By Krzysztof Kotwica

The steady demand for rock materials leads not only to on increase in mining but to the need for decreasing the loss of material in the process of exploitation as well. It brings about an increase in using of explosives in open pits and as a result an increase of after blasting gases volume, vibrations, the scattering (dispersion) of stone ect. All these factors affecting the environment lead to the research work for applying the electrohydrodynamic methods both in open casts and underground mines. In the article the authors describe the concept of this method and construction of equipment which recently have been successfully introduced in mining, the results obtained determine the possibilities of using this method and the future directions. The results of combined method with high-pressure water jets cutting and prototype equipment for separating rock blocks from the rock mass using special head with high-pressure water jets are also described.

Jan 1, 2006

Python Underground Processing Plant Critical Design The use of continuous gravity recovery in combination with a controlled breakage fine crushing and screening system followed by flash flotation has been incorporated into the Python processing plant. This provides miners with a flexible, robust, low cost, low energy pre-concentration process for the recovery of gold and/or heavy minerals. The Python plant incorporates fine crushing utilizing either High Pressure Grinding Rolls or Vertical Shaft Impactors in combination with the InLine Pressure Jig and Flash Flotation to continuously liberate and recover the valuable minerals. The use of these technologies has enabled a narrow, transportable pre-concentration plant to be produced which can easily be installed and operated in underground drifts and tunnels.

Sep 13, 2010

By W. H. Young

The thickness of the coal seam is one of the more important items influencing the productivity and general overall efficiency of operation of a coal mine. The average thickness of coal seams mined in the United States has changed very little in the past 40 years. The first measurement of thickness of bituminous coal and lignite seams was made for 1920, when the average thickness was 5.3 feet.4/ The average thickness for later years was as follows: 1945, 5.4 feet; 1950, 5.3 feet; 1955, 5.2 feet; and 1960, 5.5 feet.5/ Table 1 includes data on number and production of bituminous coal and lignite mines classified by I-foot intervals of seam thickness mined in 1920, 1945, 1950, 1955, and 1960. Though bituminous coal and lignite are mined today from seams of exceedingly variable thickness -less than 2 feet to more than 50 feet - a large majority of the production, 62 percent in 1960, came from seams 3 to 6 feet thick. This is not surprising since the coal seam of moderate thickness presents the least mining difficulties.

Jan 1, 1962

By R. T. Jones

DC arc furnaces are widely used for steel scrap melting as well as for reductive smelting of ore fines. Industrial smelting applications include the smelting of chromite to produce ferrochromium, the smelting of ilmenite to produce titania slag and pig iron, and the recovery of cobalt from nonferrous smelter slags. A number of myths and misconceptions are widely held, especially regarding: the age of the technology, the use of a hollow electrode, arc stability and shape, arc and bath radiation, interaction between the arc and molten slag, electrical behaviour of arcs and slags, a comparison between AC and DC furnaces, DC reactors, the lifespan of bottom electrodes, and the applicability of DC arc furnaces to various metallurgical systems.

Jan 1, 2011

By H. Zhu, Y. Sato, O. Takeda, K. Nakano

Recycling of rare earth magnet wastes is essential to insure the stable supply of rare earth resources. For the development of a novel recycling process, the removal of rare earth oxide from an off-spec alloy magnet was investigated by melting the alloy magnet at 1503 K together with fluoride flux, LiF-50 mol% NdF3 and LiF-?25 mol% NdF3-25 mol% DyF3. After melting, the separation of magnet alloy from the fluoride flux was achieved, and neither suspension of alloy in the flux nor suspension of flux in the alloy was observed. Oxygen concentration in the alloy decreased from 5000 mass-ppm to 160 mass-ppm by utilizing 1.5 times of equivalent amount of flux needed to completely dissolve the oxide. The investigated process is suitable for mildly contaminated waste such as a used (end-of-life) magnet because of its simplicity, low energy consumption and small limitation on location for operation.

Jan 1, 2014

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By P. A. Davies

Paper presented at the conference: Risk assessment in the extractive industries, held in Exeter, UK, 23-24 March 1994, and first published London: IMM, 1994, preprint volume, 11pp., 15 refs. Hazards such as vibration, dust emission and fragment projection can result in an area called the Danger Zone being set around a blasting site. Traditionally Danger Zones have been set solely on the basis of consequences (e.g. based on the maximum distance of rock projection or expected ground vibration plus a defined safety margin). Advances in risk assessment and its growing acceptance as a safety management tool have led to the setting of Danger Zones based on both consequences and frequency of occurrence. This allows distances to be optimised on the basis of acceptable risk levels rather than the potential consequences of infrequent events. The setting of a flyrock Danger Zone is used to demonstrate a risk-based approach compared with a traditional consequence approach

Aug 1, 1995

By M. L. Smith, G. Karunatillake

Lead-zinc production at MIM, Mount Isa includes three mines, a lead concentrator, zinc filter plant and lead refinery. Lead production is vertically integrated with lead-silver bullion shipped from Australia to London for refining. Zinc is sold as a concentrate. All three mines have reached varying states of maturity mining a multitude of orebodies having significant variation in grades and metallurgical recovery for three metals. Based on current levels of measured resources, the remaining project life is at least ten years. The objective is to schedule production over the life of all three mines so as to maximize the present value of the complex. Additional scheduling complexity arises out of the implementation of long-term schedules, capital expansion projects for both mining and processing, the presence of substantial inferred reserves and interactions with MIM copper production. A large-scale, time-dynamic, life-of-complex Mixed Integer Program (MIP) production schedule was formulated to optimize lead/zinc cash flow based on a detailed life of project production scheduling study. The requirements for such a study are detailed herein. The operational feasibility of the MIP solution is compared against a non-optimal approach to strategic life-of-mine scheduling. The strategic planning emphasis placed on the MIP is compared to the implementation of a life-of-mine schedules at Mount Isa using spreadsheets and other popular commercial mine schedulers.

Jan 1, 2003

IN presenting a'description of milling and treatment methods at the Waihi mine, it is advisable to first traverse a good deal of the past history of the mine, and show the various steps which have led up to present-day practice. The record of the company is one of steady, solid advancement, both in metallurgical and financial results. This is illustrated by the following figures, dating back from 1897...

Jan 1, 1912

By R. Sankey, L. Gatty, F. Bizzozero, G. F. Shannon, F. Savaglio, L. McDonald

State mining regulations in Queensland stipulate that a mine be provided with an earth installed on surface and that all underground equipment that needs to be earthed should be connected via a copper conductor to this surface grounding point. The regulations further require that all exposed metal surfaces in underground substations be connected to an earth. In a study of earthing conditions at Mount Isa mine it was found that the physical anchoring of metal work at substations (with rockbolts and associated steel mesh) also provides an excellent electrical connection to the country rock. It was established that not only is the mine's earthing system grounded at numerous underground locations but also that such anchor points offer, in general, a path to ground with lower resistance than does the legally required grounding point on the surface. It is recommended that metalliferous mines should utilise a multiple-earth system and not a run earth connected to a single, above-ground earth point

May 1, 1991

By Diógenes Albert Gomes

Neste trabalho são apresentados os impactos físicos e mecânicos da reciclagem de insumos refratários compostos por óxidos de magnésio ligado ao carbono, visando à reutilização destes como matéria prima para a confecção de novos tijolos. Os resíduos refratários substituíram, na formulação proposta, 100% massa de MgO utilizado nestes tijolos. O estudo envolveu a confecção dos novos tijolos e a realização de ensaios de caracterização dos tijolos produzidos, através de ensaios físicos. Os resultados mostraram uma porosidade final elevada na condição sem cura, resultando em valores de densidade e resistência inferiores aos dos tijolos produzidos com matérias-primas virgens.

Aug 16, 2017

By A. S. Argon, G. East

From their study of the anisotropy of grain boundary mobility in aluminum, the authors conclude that tilt boundaries have a higher mobility than twist boundaries because the atomic misfit at the pure-twist boundary is relatively small compared to the misfit at a tilt boundary for a given amount of misorientation. If this is true, then one would expect a twist boundary to have a lower grain boundary energy than the corresponding tilt boundary. Fig. 6, taken from the work of Gjostein and Rhines,10 shows that this is indeed the case for [001]-cu tilt and twist boundaries in the high-angle region, thus lending support to the authors' conclusion.

Jan 1, 1968

By Earl L. H. Sackett

Barite, although not a glamour mineral and probably little known to many of those in the mining business, is produced in the US. in very respectable quantities and is an important factor in the mineral economy of this country. The scope of the various uses of this mineral is perhaps one of the most misunderstood things about it, for it is surprising how many of those with a casual knowledge of the subject speak of its primary utilization in terms of paint pigments and barium chemicals. The life blood of barite utilization, however, is the petroleum industry by virtue of its dependence on this high specific gravity, inert mineral as the weighting material in its drilling fluids. From 80 to 85% of barite usage in the U. S. is accounted for in this manner-in fact, its role in oil well drilling is the only excuse for some of the large-scale barite production facilities which have been developed. Other uses are important and widely varied, but comparatively they are of small scale. They include fine crushed barite of low iron content as a component in glass manufacture, barite as a source material for manufacture of barium chemicals, finely divided barite as a component of some rubbers and ground, bleached barite in pigments. The formerly substantial use of barite in lithopone, however, has declined markedly because of replacement of lithopone by titanium pigments

Jan 5, 1962

By D. B. Felsher

"Lakeshore Gold’s Bell Creek Mill is located in Timmins, Ontario. The mill has been in operation since 2009 and has undergone several small expansions since then. In 2012 - 2013 the first major mill expansion was commissioned raising the mill capacity from 2,000tpd to 3,150tpd. This was done through the installation of a new ROM ore truck dumping facility, jaw crusher, ore storage dome, SAG mill, leach tank, CIL tank, and electrowinning cell. This paper will cover the equipment installed to raise the tonnage as well as the commissioning of the new equipment including problems encountered and how these problems were solved.IntroductionLake Shore Gold acquired the Bell Creek Mill, along with the Bell Creek Mine, from the Porcupine Gold Mines Joint Venture, a joint venture between Goldcorp Canada Ltd. and Kinross Gold Corporation, in December 2007.The Bell Creek mill, which processed ore from the Bell Creek Mine has consistently achieved recoveries of over 95%, is a conventional gold mill circuit, involving crushing and two stage ball mill grinding, gravity and leaching, followed by Carbon-In-Pulp (CIP) process for gold recovery. The facility had been placed on care and maintenance in 2002. At the beginning of 2009, the mill had been refurbished with an initial capacity of 800 tonnes per day and was subsequently refurbished to a capacity of 1,500 tonnes per day near the end of the third quarter of that year. The Mill was then expanded in 2010 to a capacity of 2,000 tonnes per day.In late 2011, the Company commenced a 50% expansion of its milling facility, from a processing capacity of 2,000 tonnes per day to 3,150 tonnes per day. Phase 1 of the expansion, which mainly involved enhancements to the solution circuit (“back end”) and increased the mill’s capacity to 2,500 tonnes per day, was completed at the end of 2012. Commissioning of Phase 2 of the expansion, to a capacity of 3,150 tonnes per day, commenced at the end of July 2013."

Jan 1, 2015

By J. R. Thoenen

Profits in the crushed-stone industry, as in any other, represent the difference between selling price and production cost. When consumer demand increases rapidly, as occurred in the crushed-stone industry from 1918 to 1927, selling prices tend to rise. Cost of production usually rises, also, owing to the expense of expanding facilities, searching for and developing new quarries, and purchasing, installing, and operating new equipment. Frequently, also, the inattention of managements to the details of operating costs is responsible for their increase. This is not due to negligence but rather to the necessity of confining attention to the problems involved in producing material to supply orders. When market conditions change and consumer demand becomes stabilized or contracts, the producer's attention usually is directed to assuring the orders necessary to keep his enlarged facilities busy. Hence, competition increases and soiling prices decline.

Jan 1, 1939

The addition of cement to underground backfill at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited, Broken Hill commenced in 1967. A deterioration in metallurgical performance at each concentrator occurred as a result, with increased loss of lead and zinc to residues. Investigations to determine the reasons for this problem and methods to counteract it have been undertaken. This paper outlines the effects of cement on lead-zinc beneficiation at Broken Hill and presents an interim report on attempts to overcome the metallurgical deterioration.

Jan 1, 1971

By W. H. Langer

At the start of the 20th century Denver?s population was 203,795. Most streets were unpaved. Buildings were constructed of wood frame or masonry. Transport was by horse-drawn-wagon or rail. Statewide, aggregate consumption was less than 0.25 metric tons per person per year. One hundred years later Denver had a population of 2,365,345. Today Denver is a major metropolitan area at the crossroads of two interstates, home to a new international airport, and in the process of expanding its light rail transit system. The skyline is punctuated with skyscrapers. The urban center is surrounded with edge cities. These changes required huge amounts of aggregate. Statewide, aggregate consumption increased 50 fold to over 13 metric tons per person per year. Denver has a large potential supply of aggregate, but sand and gravel quality decreases downstream from the mountain front and potential sources of crushed stone occur in areas prized for their scenic beauty. These issues, along with urban encroachment and citizen opposition, have complicated aggregate development and have paved a new path for future aggregate development including sustainable resource management and reclamation techniques.

Jan 1, 2009

By Robert H. Peters

The U.S. Bureau of Mines has prepared this report on strategies for maintaining high job attendance among underground coal miners because high absenteeism is a threat to miners safety and seriously hampers productivity. A substantial number of research studies on the effectiveness of various strategies for reducing absenteeism among the employees of nonmining industries have been reported in the literature. These strategies have aimed at improving job attendance through one or more of the following: (1) improving employment procedures, (2) overcoming problems that adversely affect one's ability to attend work, and (3) increasing miners motivation to attend work. Many of these strategies appear applicable to the mining industry, and are reviewed in the first half of this report. The second half of this report describes how one could develop and implement a program for maintaining high attendance at underground coal mines. The steps include: measuring and evaluating attendance levels; formulating attendance goals and an absenteeism policy; developing and implementing an attendance promotion program; and periodically going through the preceding steps known as recycling.

Jan 1, 1989

By Hongjie Yang

The No. 10 metro line of Shanghai city is 36 kilometers in length and will pass through the operating airport runway by using tunnel boring machine with earth pres-sure balance mode. Although there are examples through world that tunnels pass through airport runway and tunnelling underground is not a difficult undertaking technically, there is rare experience in China for the similar projects especially in Shanghai saturated soft soil region. Shanghai soft earth is famous for its high compressibility, high rate of water content, weakness in strength, large deformation and different characteristics in earth strata. Besides, the whole construction process will be under ultra-large airplane dynamic load on the surface ground over the tunnel, which increases the risks of construction process. This paper evaluates the feasibility of building the metro tunnel under such an extremely serious condition, especially the subsidence of ground surface caused by advancing of tunnel boring machine, which also is the most important control target for the safe operating of the runway. Furthermore, this paper discusses the effective measures to keep the settlements in the permissible level during the whole working period for the tunnel from aspects of plan, design and construction.

By H. H. Einstein

This paper reviews how uncertainty has been dealt with over the past 40 years using the decision making cycle as a frame of reference. The review of the phases of this cycle, as applied to rockmechanics and rock engineering, namely characterization, performance analysis, updating and decision making shows that in each, progress has been made over the past 40 years, although most of the basic concepts existed already in the 1960’s. Characterization is the area in which the greatest scientific steps were taken, this phase and performance analysis also gained from the tremendously expanded computational capabilities which allow one to use both more complex and more practically oriented models. The greatest practical advance is without using any doubt in risk based decision making although its acceptance shows interesting differences between different professions. Dans l’article suivant on utilise le cycle de décision pour illustrer le développement du traitement des incertitudes en mécanique des roches et en construction en roche dans les quarante années passées. La revue des phases du cycle de décision montre qu’on a fait du progrès dans chaque phase du cycle de décision, c’est à dire dans la caractérisation, dans l’analyse et la prédiction du comportement, dans l’actualisation et dans l’acte de décision, même si les concepts fondamentaux existaient déjà dans les années 1960. Les plus grands avancements scientifiques se trouvent dans le domaine de la caractérisation tandis que l’analyse prédictive profitait du développement de l’informatique qui a mené à des modèles plus complexes mais aussi plus pratiques. Le plus grand progrès est sans doute dans le domaine de l’acte de décision sur la base des risques. Ce procédé est devenu assez commun même s’il y a encore des différences d’acceptation entre différentes professions. Im vorliegenden Artikel wird der Entscheidungszyklus gebraucht, um darzustellen wie sich derUmgang mit Unsicherheiten im Felsbau während der letzen 40 Jahre entwickelt hat. DerÜberblick über die Phasen des Entscheidungsprozesses zeigt, dass bei der Anwendung in derFelsmechanik und im Felsbau, in allen Phasen d.h. bei der Charakterisierung, bei der analytischenVorhersage, beim Aktualisieren und bei der Entscheidungsfindung Fortschritte gemacht wurden,obwohl die grundlegenden Konzepte bereits in den 1960er Jahren existierten. Im Gebiet derCharakterisierung gab es wohl die grössten wissenschaftlichen Entwicklungen, während dieanalytische Vorhersage vor allem von den Fortschritten der Informatik profitierte, welchekomplexere wie auch praktischere Modelle möglich machte. Der grösste Fortschritt ist ganz sicherin der Entscheidungsfindung zu beobachten, wo Risikobetrachtungen gang und gäbe sind, obwohlhier noch einige Unterschiede zwischen verschiedenen Berufsgattungen zu finden sind.

Jan 1, 2003