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By C. Keefe, O&apos

Measurements of the quantity of entrained air within processes have challenged instrumentation developers for years. This is particularly true in the unique and demanding operating environment and applications seen in minerals processing. In minerals processing applications, entrained air plays a role in errors seen within nuclear density gauge measurements and in pumping efficiency. It is also the major component of flotation processes. The measurement of the quantity of entrained air, known as the gas void fraction, can now be performed from the outside of a process pipe through CiDRA?s patented passive sonar array-based technology. Within column cells, the need for a robust, no maintenance, accurate means of measuring the entrained air, known as gas holdup, has resulted in a submersible version of this technology. CiDRA?s meter technology calculates the gas void fraction by first measuring the speed at which naturally occurring sound in the process slurry propagates past an axial array of sensors. These sensors are incorporated in a band that is wrapped around the outside of the pipe, resulting in no process downtimes for installation and unprecedented reliability. A known relationship between this speed of sound and the entrained air captured in the form of bubbles within the slurry is then applied in CiDRA?s meter to calculate the gas void fraction. This paper will present the measurement technology, its operation, its calibration and its application in a variety of gas void fraction and gas holdup measurement situations such as pumping efficiencies, hydrocyclone operation, external sparging, and column cells.

Jan 1, 2008

By R. Raby

During the 1980 decade, the rapid price increase for flake graphite has generated a high degree of interest for the discovery and the development of alternate occidental sources of supply in response to fluctuations in quality and availability from current producers. Alike many industrial minerals, graphite draws its complexity not only from its mineralogy and unique properties but also from the very large spectrum of industrial applications each calling for specific quality criterion. As new high technology uses are being developed, more rigid specifications will apply. Discovered during the latter part of 1988 by Mazarin inc., some 30 Km South of Fermont near the Quebec-Labrador border, the Lac Knife deposit was quickly identified as one of the world major long term alternate source of stable supply for this mineral. This paper also reviews the status of the project development as of late 1991, while updating previous papers published by Industrial Minerals1990 and Mining Magazine 1990.

Jan 1, 1992

A hidden asset in most exploration and mining activities is data. Common practice involves the spending of large amounts of money to discover, define and prove the viability of a mining project. Some organisations have used operations research analysis and internal costing methods to allocate a value to their data and to compare the costs of data maintenance to other more tangible activities like plant and equipment maintenance. Those organisations, which do not undertake such an analysis often, have little knowledge or understanding of the extent and the worth of their data. Often the organisations lack of knowledge and understanding of the data is indicated by their failure to fully exploit or realise their opportunities. The focus of this paper is to discuss new technologies that optimise the management and security of collected and derived data. The technologies discussed are components of the software systems acQuire and MineSight.

Jan 1, 1999

The uphole bench extraction strategy at EKJV Management Pty Ltd?s Raleigh Mine, requires simultaneous horizontal and vertical exposure of paste filled stopes. In order to prevent excessive ore dilution, the paste fill must be of sufficient strength to prevent failure during exposure. A numerical modelling methodology has been developed to accurately simulate the initial stress distribution within paste filled stopes, together with the strain-softening loading response of paste fill material. Due to the narrow orebody width and high deformation behaviour of the host rock mass, high closure strains are likely to cause a stiff, brittle fill material to undergo crushing failure upon exposure. The stability of paste fill exposures at the Raleigh Mine was determined by conducting a series of three-dimensional numerical models that incorporate the extraction, filling and exposure sequence of paste filled stopes. Stability charts for 2.5 m and 3.5 m wide simultaneous horizontal and vertical exposures have been derived based upon the numerical modelling results. Implementation of the stability charts has proved successful in limiting the amount of ore dilution from paste fill and provides a basis to optimize paste fill cementation and stability throughout the life of the mine.

May 1, 2007

By AIME AIME

THE 129th meeting of the American Institute of Mining and Metallurgical Engineers convened at New York City, in the Engineering Societies Building, Feb. 18-20, 1924. On February 21 an excursion was made to the Bethlehem Steel Co., at Bethlehem, where about 200 members and guests were splendidly entertained. An illustrated description of the Bethlehem Plant will be published next month. The meeting and excursion were largely attended; the registration at New York totalled 1276 versus 1201 in 1923. William Kelly, long identified with the iron-mining industry of the Lake Superior district, was elected President of the A. I. M. E. for the coming year, at ,the annual business meeting, Feb. 19, succeeding E. P. Mathewson. The following Directors were also elected (the date signifies year of termination of office; the final figure indicates the "District" the Director represents).

Jan 1, 1924

The prediction and control of ground deformations due to underground mining are important considerations in the permitting, planning, and monitoring of coal mining operations. The prediction of mining-induced ground movements using the influence function method is a mature technology and is widely used in many coal basins around the world. Such movements mainly include subsidence, horizontal displacement, and horizontal and/or ground strain. Predictions can be accomplished using regional subsidence parameters and site-specific data.

Jan 7, 2020

By Najdat I. Aziz

There are different schools of thoughts about the influence of gas pressure on coal strength. Researchers have reached contradictory results with regard to the effect of confining gas pressure on tensile strength of coal. Accordingly, this paper re-examines the influence of gas pressure on the strength of coal. A specially designed precision drill capable of drilling in a pressurised chamber was used to drill coal samples under both atmospheric and increased gas pressure environment. The drill cuttings were examined for particle size distribution using a laser controlled Malvern Mastersizer S particle size analyser. Petrographic analysis of the sample examined the effect of gas pressures on the maceral structure and the composition of coal. The paper demonstrates that there is a definite variation in the range of particle size distribution with particles obtained from drilling coal samples not subjected to gas pressures, in comparison with those obtained from samples drilled under confined gas pressure. Also observed were the changes in the rate of drilling in soft coal obtained from geologically-disturbed zones compared with other coal samples. Some variation on the maceral compostion of coals were also observed in relation to increased gas pressures and gas type.

Jan 1, 1996

By B. Q. Xiao

The nitrate content is an important factor for environmental water samples and flour. In a 0.35 mol/L H2SO4-2NO solution, has a strong catalyzing function on the decolourization of Gallocya-nine (GC) oxidated by NaBrO3. Based on this, a novel method was developed to measure the NO and -3NO concentrations in water and flour. The flow injection technology was introduced into the analysis system. A single-valve dual- cingulums to inject which the Copperized-Cadmium slice and the reduction zone are isolated. The optimum solution for this method contains 1.48×10-4 mol/L GC, 0.06 mol /L NaBrO3 and 0.2 mol /L of NH4-2NOCl. Two empirical equations were proposed to calculate the and -3NO concentrations based on the measured signals. It can be used to measure -2NO of from 0.001 mg / L to 2.0 mg/L and -3NO of from 0.002 mg / L to 2.5 mg/L. The measurement frequency can be up to 20 samples / h. The relative standard deviation for eleven samples is less than 5%.

Jan 1, 2014

By Denis Labrie

Le minage en profondeur sous contrainte modérée à élevée présente de nombreux défis aux opérateurs et aux ingénieurs de mine notamment au niveau du contrôle de terrain et de l?environnement minier souterrain, pour assurer la sécurité des travailleurs sous terre et la continuité du cycle d?opération. Des conditions de contrainte élevée signifient une pression accrue au front de taille et sur les structures minières tels les piliers de mine et les fins de zone, un risque de rupture violente ou de coup de toit plus élevé, des zones de rupture plus grandes au pourtour des excavations, des charges accrues sur le support de terrain, etc. Le présent article fournit un aperçu du travail fait à l?intérieur du Programme de Contrôle de terrain de CANMET au cours des sept (7) dernières années, entre 1995 et 2001, pour comprendre et suivre l?évolution des niveaux de contrainte à l?intérieur des structures minières. Les propriétés déterminées en laboratoire sur des échantillons rocheux et les prévisions effectuées au moment de la conception sont comparées avec les observations effectuées en chantier à la paroi des excavations et à l?intérieur de la masse rocheuse. La plupart des cas discutés ici montrent une corrélation satisfaisante entre les observations effectuées en chantier d?une part, et les résultats d?essai obtenus en laboratoire et les calculs réalisés lors de la conception d?autre part. Ces observations peuvent donc être considérées comme des moyens relativement sûrs pour vérifier et suivre l?évolution des niveaux de contrainte présents à l?intérieur des structures minières.

May 1, 2002

By Thomas E. Marshall, Michael Dunn, L. J. Prosser, Anthony T. Iannacchione

During the past few years, the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) examined and characterized conditions at a majority of the underground stone mines in the United States. Observations at these mines revealed a limited degree of roof monitoring beyond visual inspection and sounding. When monitors are used, they typically require the miner to measure movement at the roof. If conditions are unstable, the mine rmay be in a hazardous situation while recording data. Based on this scenario, researchers surmised that a simple, inexpensive monitor with the capability of recording data at a distance from the mine roof would be a safer way to gain the information. Additionally, more widespread use of monitors could potentially lead to better understanding of roof movement in general. A monitor to meet this need was designed, tested, and subsequently improved as experience was gained in its’ use at a number of underground stone mines. The Roof Monitoring Safety System (RMSS) can provide an initial indication of movement in roof beams. By understanding and measuring roof movement in underground mines, the potential for injuries and fatalities to mine workers from falls of ground can be reduced. Also, officials at a mine with a history of data are better prepared to make a decision on remedial actions in the event of ground falls. This paper will outline the evolution of the RMSS and how it can be used in a comprehensive proactive ground control safety program. Also included is a case history describing how the RMSS was used in an evaluation of the effectiveness of a mechanical impact scaling machine at an operating limestone mine.

By Clarence Hall, CHARLES F. MUNROE

Of the common causes of the larger mine accidents, such as falls of roof and coal, gas and dust explosions, mine fires, and the misuse of explosives, all of which are often closely related, each must be studied and fought in a manner peculiar to itself. The last mentioned, the misuse of black powder and other explosives, is sometimes considered the least important of these causes of mine accidents; but its impor- tance is much greater than the statistics indicate, for the reason that the misuse of explosives is the true cause of many of the fatal mine fires, gas or dust explosions, and falls of roof that are credited to other causes. Both the quantity of explosives used and the number of purposes to which they are applied are increasing. They are now made at about 150 plants, in different parts of the United States, and the product of a single year is estimated at nearly 500,000,000 pounds. Nothing in all this material is a safe or "safety" explosive when in the hands of a careless or ignorant person; and this is true whether considered in connection with the shipment or the use of these explosives. In addition to the large losses of life and property resulting from an improper use of explosives in mining, the recent statistics of the railway bureau for the safe transportation of explo- sives have shown more than 400 persons killed or injured and over $3,000,000 worth of property destroyed by explosives in transit by rail. The fact that three years of cooperative effort under the wise supervision of this bureau has reduced these losses to almost nothing encourages the hope that similar cooperative effort may likewise greatly lessen losses of life and property from the use of explosives in mining. The additions to the large death roll of our mines make a recurring appeal to the public for fair treatment of the coal-mining industry, and to the miner and the manager that they join in every possible effort for greater safety. It may never be possible under conditions such as exist to-day to prevent mine accidents entirely. Little can be accomplished in that direction by either the operators or the miners working alone, but experience in all countries shows that

Jan 1, 1911

The study of gas emitted from face coal samples at the coal face is part of an investigation of instantaneous outbursts of coal and gas. Normally, seam gas essentially comprises methane of which the origin in the metamorphism of coal is undoubted. The origin of other gases sometimes occurring in high proportion in seam gas, particularly carbon dioxide, is more controversial. A simple meter for rapidly assessing gas in coal was developed. Tests with the meter enabled comparisons of seam gas in face coal at some outbursting and nonoutbursting mines, and under various working conditions. The varying results of widespread testing suggest certain trends, including some prospect of recognising outbursting potential at the coal face.INTRODUCTIONThe aim of this work is identification of differences in gas condition between coals subject to instantaneous outbursts and coals which have not outburst, and between faces of coals which will and which will not subsequently outburst. Any comparative test should be conducted right at the coal face on coal about to be worked and the results of testing should be available after a short period. Moreover, the method and the comparison of results should require no special skill, and be well within the capacity of junior mine officials. Any consistent relation between gas condition and subsequent mining conditions - outbursting or not might be valuable in prediction of outbursts.INSTANTANEOUS OUTBURSTSInstantaneous outbursts (Hargraves, 1958) , are largely unpredictable and unaccountable ejections of coal (up to 5,000 tons) and gas (up to 5,000,000 cu.ft.) from a standing coal face. Usually the gas is essentially methane (CH4 ) but may be essentially carbon dioxide (C02 ), or an intermediatemixture...

Jan 1, 1962

By P. E. Lenz

In Nevada, large deposits of diatomite were formed during the Miocene / Pliocene in deep, alkaline lakes. Associated sediments are predominately fine-grained lacustrine with varying fluvial-clastic layers. Tephra layers are common, and probably served as a source of soluble silica for the extensive diatom colonies. Four companies are currently producing diatomite from Nevada deposits. Nevada ranks second to California in annual domestic production. Nevada diatomite is used in filter aids, fillers, absorbents, catalyst supports, and many other products. Economics and mineral reserves indicate that diatomite production in Nevada will be significant well into the next century.

Jan 1, 1993

By Emre Biringen

"Results from a small-scale laboratory experimental program show the changes in the vertical stiffness and strength of a soft clayey soil adjacent to the shaft of an inserted pile (i.e. expansion of a cylindrical cavity). The experimental program provides a realistic axi-symmetric physical model of an element of a cylindrical pile and the surrounding soil. The study interprets the improvement and assesses its magnitude in vertical stress-strain-strength properties of a normally consolidated soft cohesive soil in response to preloading impact in the radial direction. The results verify that insertion of a cylindrical pile causes densification of surrounding soil in a radial direction due to change in stress state around the pile, and thus consolidating and stiffening of the soil.The test results indicate that most improvement in modulus and strength takes place within a distance of 4 times the radius of a pile, though significant improvement is realized to a distance of 8-10 times the radius, beyond where there is negligible effect. Settlement characteristics of the surrounding soil in a zone of 12 times the pile radius improve significantly after the formation of a cylindrical cavity. The miniature vane shear strength tests show a 1.5 times increase in a zone of 4 times the pile radius compared to the strength at 10 pile radii. The results also imply that the spacing of cylindrical piles should not be more than 4 to 10 times pile radius, so that the surrounding soil matrix may improve the vertical bearing capacity under any foundation or embankment loading.INTRODUCTIONThe engineering community is familiar with different techniques to improve the bearing capacity and settlement characteristics of weak cohesive and organic soils. Some of the in situ techniques to improve the properties of soft ground (e.g. soft clays) prior to placement of foundations are vertical preloading, deep cemenUlime mixing, stone columns, and grouting (Henn 1996; Moseley 1993). In addition to these methods, researchers have recently showed interest in achieving soft ground improvement by means of applying radial compression method for which different names exist including expanding pile (Kelleher et al. 2001 ), Preload™ Pier (Biringen and Edil 2003), and sand compaction pile (Lee et al. 2004). Handy (2001) has described how preloading can also be achieved by imposition of radial loading in soft ground with an expected improvement in stiffness. The idea behind the latter method is densification and consolidation of soft soil in the radial direction by controlled displacement for which the process can be viewed as a cavity expansion problem (Vesic 1972)."

Jan 1, 2005

By S. H. Ward

Since the advent of the first airborne electromagnetic system, it has been evident that such systems were inherently limited to shallow depths of exploration of the orderof 100 to 200 feet. Hence in 1948 the author and his associates commenced a study of the feasibility of applying natural audio frequency magnetic fields to investigation of the electrical properties of the subsurface in order to provide a system capable of overcoming this limitation. This research culminated, in the summer of 1958, in the development of a new airborne prospecting device — AFMAG. This device has detected surface massive sulphide bodies while flown at heights as great as 3000 feet. Hence, by inference, it is deduced that it could find similar sulphide bodies if they were buried 2500 feet below surface and the aircraft flown at 500 feet. Thus a considerable improvement over conventional airborne electro-magnetic systems is obtainable with AFMAG. Airborne exploration in mountainous terrain involving deep valley fill now becomes possible. Examples are presented of the results of actual airborne AFMAG test surveys over known deposits of massive sulphide mineralization. Interpretation of the data is discussed with particular reference to the knowledge of size, dip, depth, depth extent, and conductivity of causative bodies as deduced from the flight records. The possibility of mapping major geologic structures, for both mining and oil exploration purposes, is discussed with the aid of examples of airborne AFMAG data. INTRODUCTION Electrical prospecting with natural audio frequency electromagnetic waves as a source has, within the last three years, become a practical reality. Both airborne and ground survey instruments under the trademark "AFMAG" (for audio frequency magnetics) have been used successfully in the search for conductive mineral deposits. It is the object of this paper to discuss the principles of airborne AFMAG and to illustrate its application by means of examples obtained over known geological situations. WHY AFMAG? In view of the large number of good airborne electromagnetic systems available for purchase or contract surveying, one may well ask, "Why another new system?". Primarily the answer lies in the fact that AFMAG does not suffer from the very limited depth of exploration available with, and inherent in, any conventional airborne electromagnetic system. AFMAG is not conventional insofar as an artificial transmitter is not required. Only a receiving and detecting device is employed. The electromagnetic fields measured are those from millions of electrical discharges in the atmosphere (e.g;..- lightning strokes). Their random distribution in time and space make these fields difficult to employ and it is only with recent advances in the electronics of geophysical instrumentation that this has become possible. A second reason for AFMAG and one of its

Jan 1, 1961

By J. R. Linney

A HISTORY of the ore-mining and iron-smelting industry of the Adirondacks comprises a century and a half of pioneering by rugged individualists, both men and women. By geographical location, the climate is most severe-long, cold winters with heavy snowfall, and short seasons of vegetation growth; this, together with its remote location from large centers of population, adds considerably to the difficulties of conducting mining operations in this area.

Jan 1, 1943

By John D. Sullivan, Alfred P. Towne

"In copper percolation-leaching plants the ore is usually crushed to a maximum size of about three-eighths inch. Ordinarily an ore is crushed as finely as feasible since the rate of extraction of copper is increased with decreasing size of particles owing to the greater surface exposed and. the shorter path required for solutions to come into contact with the minerals to be dissolved. However, greater degree of crushing also increases the amount of fines. When ores are charged into leaching vats the coarse and fine material tend to segregate, resulting in channeling of solutions and leaving the areas where fines predominate only partly leached. An improvement in the method of charging the ore into vats that would minimize the deleterious effects of the segregations of fines would increase the percentage extraction of copper.The Inspiration Consolidated Copper Co.4 recently installed classifiers to remove the primary slimes from the ore, before charging it into the leaching vats. This necessitates a separate agitation treatment for the slimes.Recent publications5 of the bureau have shown the advantages of agglomeration followed by trickle leaching to extract copper from concentrator tailings. It was shown that when equal parts of ore crushed to about 1/4-inch size and concentrator tailings were agglomerated with approximately 10 per cent of moisture, either in the form of water or leaching solution, and the mass was charred into a leaching vat the ore could be treated successfully by open-drainage trickle leaching. Even with 30 or 35 per cent of minus 200-mesh material present the ore could be leached, if it was not flooded with solution.The results obtained in agglomerating ores and slimes suggested the possible advantages to be gained by wetting the crushed ore for standard percolation-leaching plants before charging it into the vats. Wetting the ore whould make the fine material and slime cohere to the larger pieces of ore thus tend to prevent segregation when the ore is charged into the vats. The bureau, at its southwest Experiment Station and in cooperation with the Department of Mining and University of Arizona, Tucson Ariz., therefore made a study to work: out A way in which slimes could be handled in percolation leaching. The study showed that the method of charging ore into the leaching vats governed the distribution the fines and consequently the rate extraction of copper. The results of the study reported in this paper."

Feb 1, 1931

By David Kress

Mill crushing drive systems are essential to cement producers. With the increased emphasis on operating efficiency, it is vital that these systems be dependable and reliable. No one needs the costs or headaches associated with unscheduled downtime or inefficient machinery operation. A reliable drive system starts with the proper selection of the ring, or girth, gear and continues through proper maintenance. Ideally, selecting the right girth gear brings together the gear manufacturer, the system designer and the end user. The gear manufacturer must know the details of the application, the demands that will be placed on the gear and the nature of the equipment to be driven. Similarly, the user and the system designer must be familiar with the variables that affect gear drive performance and service. For example, an application that places a torque load on the drive in excess of its rated capacity will result in gear tooth distress and, in severe cases, breakage.

Jan 1, 2000

By Caitlin Rogers

The environmental and economic sustainability of froth flotation is dependent on effective management, which in turn improves the performance of a concentrator. In economic terms this means improved recovery of valuable minerals, in environmental terms this means effective management of acid generating tailings. Three indicators were selected to measure the performance of an integrated flotation system. The system consists of two stages of flotation; valuable mineral flotation followed by environmental desulfurisation by froth flotation. The suitable indicators were selected based on their fulfilment of four attributes. An attribute is a desired aspect of an indicator. The four attributes were: comprehensive, relevant, sensitive and quantitative. Two environmental indicators and one economic indicator were selected. They represent revenue generation from valuable minerals and environmental cost of management. The suitability of the selected indicators was shown using illustrative scenarios.

Jan 1, 2014

By A. W. Hall

A nuclear method was developed for continuously and automatically deter-mining the moisture content of coal flowing through a bin. Fast neutrons from a 1 curie americium-beryllium source penetrate the coal, are thermalized (slowed down) by hydrogen in the moisture, and are counted by a thermal neutron detector. The difference between the number of these thermal neutrons and those thermalized by dry coal (in a reference drum) is a measure of the moisture content of the coal. A materials handling system was developed and in tests at a commercial coal preparation plant, moisture in coal was monitored continuously within 0.2 percent of values determined by conventional means. The meter responded rapidly to change in moisture content, making it adaptable to automatic process control, and was operated for 1 year without malfunction or recalibration. Shielding of the source by the coal kept the neutron flux level at the bin wall less than 1 milliroentgen per hour, a safe level for personnel.

Jan 1, 1973