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By J. H. Swisher

Two recent papers in this journal1,2 contain experimental evidence for an anomaly in the concentration gradient for tracer diffusion. In both papers, the authors suggest that this anomaly is due to a Gibbs' absorption effect. Their hypothesis is that surface active tracer elements tend to remain in or near the surface adsorption layer, thereby altering the diffusion flux and concentration gradient. It is not clear how the anomaly can be explained in terms of an adsorption effect. Surface tension forces act parallel rather than perpendicular to a surface and therefore should affect only the rate of spreading of surface active agents tangentially across a surface. Frenkel3 has given a short treatment of surface tension as a driving force for surface diffusion. While the equilibrium concentration of a surface active agent at the surface of a solution is known to be higher than in the bulk, its chemical potential is necessarily the same. It is difficult to see how adsorption can result in an anomaly in the chemical potential gradient, which is the driving force for diffusion. A more detailed explanation by the authors of the adsorption mechanism is in order. A similar anomaly does not seem to arise where

Jan 1, 1970

By Andrea Brickey, Ethan Marcoux

The South Dakota School of Mines and Technology (SD Mines), located in Rapid City, South Dakota, is one of only a few universities in the United States that offer a Bachelor of Science in Mining Engineering. The Department of Mining Engineering and Management (MEM) at SD Mines teaches courses that introduce students to concepts related to mining, including a course covering explosives engineering. Students are taught the basics of explosives theory and application in the mining and construction industry through a series of lectures and assignments. With limited field experience, many students find some topics difficult; these include: flyrock, ground vibration, timing, and others. Some US mining schools have an experimental mine in which they can simulate field conditions and conduct hands-on training, but not all universities have such facilities. For those without, teaching certain concepts can be more challenging in a pure classroom environment. To counteract the lack of an experimental mine, the mining department at SD Mines implemented Paradigm (Version 18.4.4984.0; McKenzie, 2017) a computerbased blast modeling software to improve the learning environment.

Jan 1, 2019

By Harold Rabling

THE following notes are taken from results obtained on a standard 25-ft. Hancock jig 1 tested during regular operation in the Bonne Terre mill of the St. Joseph Lead Co. The object of the tests was to determine the conditions for most effective 'work, and the nature of products that could be made. The material treated was sized between 9mm. and 2-mm. round-hole screens, and was constant throughout the experiments, Three products were made, concentrates from the first three hutches, middlings from the fourth and fifth, and tailing from the sixth. The middlings were crushed in one pair of Allis-Chalmers Style B 30 by 14-in. rolls, and elevated with the original ore to the 2-mm. screens, oversize of which formed the jig feed. While this arrangement was very simple, it gave rise to undesirable crowding of the circuit. Table 1 shows tonnage and assay values of the jig feed and products at the beginning of the experiments, and brings out the excessively large amount of middlings, comprising 63.3 per cent. of the total material fed to the jig. The rolls, being heavily overloaded, did very little crushing, a screen analysis of the product showing that only 27 per cent., or 128 tons, was crushed fine enough to pass to the tables. The remaining 347 tons returned to the jig with 400 tons of original ore. At times, this overcrowding became much worse, and the tonnage in circuit grew to enormous proportions. It became imperative

Jan 8, 1917

By Harlowe Hardinge

THE sound made by ball, pebble and rod mills has long been used by the operator as the "telltale" of their operation. The nature of this sound depends upon local conditions and the type of mill used. By experience an operator can tell whether the mill is running properly or not. Some operators are able to detect the difference in sound much better than others and get better results running the same mill tinder the same conditions. The automatic operation of a mill using sound as the fundamental means for maintaining control presents many problems. The satisfactory solution of these problems requires, for given operating conditions, a greater average output, with improved product for subsequent processing, than can be obtained by manual control.

Jan 1, 1939

By John Eggert, Paul Benford

"Since 1982, Placer Dome Inc. -Dome Mine has steadily increased mill throughput. Tonnage has increased from a nominal design capacity of 3000 short tons per day, attained in 1985, to 4130 stpd by the end of 1992. Many minor and major circuit adjustments were tried to maximize tonnage.Having utilized most conventional means of increasing tonnage, further increases required a newer approach. This paper discusses the Dome experience in the development and implementation of an expert system.The Comdale/C system was chosen for a controlled trial. The criteria for acceptance were: increased tonnage had to be sufficient to pay for the system; the increase had to be visibly sustainable and the mill operators had to be willing to accept the system.The criteria for purchase were met during the trial and the system was purchased. The system continues to perform well. The tonnage throughput increase has been sustained while operator acceptance remains high.IntroductionPlacer Dome Inc. -Dome Mine is Canada's oldest operating gold mine. The mine was among the first established in the Porcupine camp in what is now Timmins, Ontario. The City of Timmins is located approximately 500 miles or 800 kilometres north of Toronto. Figure 1 shows a map of the province of Ontario and the mine location.In 1912, milling began at a rate of 350 short tons per day. With two minor exceptions, milling has been continuous since this time. The first of these shut downs was in 1918 during the first world war. The war created labour shortages which forced the mine to stop production for more than a year. The second was in 1930 when fire destroyed the mill."

Jan 1, 1994

By Kevin Dunfield

The Deltadet System is composed of: The Deltadet II electronic Detonator. A Field Terminal to create, modify or simply execute an existing blasting sequence. The radio remote controlled option is composed of a Base Station to program, calibrate and initiate the EDDs plus a Blasting Box to send commands to the Base Station. Blasting lines to connect the EDDs to the Base Station (100m) and Visual Blast software to create or modify a blasting sequence.

Jan 1, 2004

By Chas. Kohl

ABOUT 1929 an engineer was engaged to organize a Safety Department, lay out an educational program, and achieve a reduction in accident frequency. Due to the large number of employees, about 12,000, and the distances between the various properties, it was a big undertaking. Most of the workmen are from the Sierra and for generations have been agricultural people, with little conception of modern tools and machinery, and to a large degree are illiterate. However, gratifying results have been obtained, as evidenced by the accident frequency curve during the sixteen-year period. Safety offices have been established in each of the six major properties, staffed by men who devote their entire efforts to inspections of working conditions and equipment, instructions as to safe methods, and investigations of accidents. The Corporation is a member of the Inter-American Safety Council, receiving their publications and literature, which serve to keep us up to date and informed on modern methods. Dissemination of this material is accomplished chiefly through word-of-mouth and bulletin boards. When it is found that the accident rate is increasing in a certain occupation, as for instance underground haulage or mine hoisting, the operators so engaged are assembled and given renewed instructions on the safety code pertaining to their work. Inter-camp competitions in accident avoidance are being conducted, with annual awards for that unit having the lowest severity rate for the year.

Jan 1, 1945

Lower the respirable dust expo-sure of longwall mine workers by reducing the amount of air-borne respirable dust generated during coal extraction. Approach Increase the moisture content of the coal seam through water infusion before the coal is mined. How Water Infusion Works Increasing the moisture content in coal tends to prevent respirable dust from becoming air-borne during mining and transport. The moisture content of the coal seam can be increased by infusing water into the seam. Water under pressure is forced into the cracks (cleats) of the coal seam through sealed bore-holes. The effectiveness of water infusion is a function of the amount of water the coal seam accepts (its infusibility), which depends on the cleat density (cleat spacing) and cleat size (crack diameter). Thus the effect of water infusion on dust control depends mainly on coal seam characteristics. Water infusion techniques are generally used to restrict the flow of methane gas to the working face; however, the technique provides an alternative dust control method in mines with severe dust problems which limit production.

Jan 1, 1987

By G. C. Trevorrow

STRIP mining during 1943 increased considerably with further extension of mechanical loading in mines already partly mechanized; with the considerable introduction of mechanical loading into hand-loading mines; and with improvements in the use of loading equipment. Extension of the use of machinery both in strip mining and underground is due to reduction in labor supply and increased cost of labor, together with the increased demand for coal during the period of labor shortage.

Jan 1, 1944

By Miguel A. Huaman

El presente artículo tiene el objetivo de discutir las consideraciones técnicas para el análisis de rotura de presas de relaves sobre la base de la experiencia en el desarrollo de estas simulaciones en varias presas de relaves en el Perú, las cuales contemplan dos puntos importantes: la generación del hidrograma debido a la liberación del relave, y el tránsito del hidrograma generado a través de un cauce o terreno natural. Para la generación del hidrograma de rotura de la presa se asumen los probables tipos de falla como terremotos, eventos meteorológicos extremos, manejo inapropiado del depósito, vandalismo, entre otros, de acuerdo a las condiciones o características de la zona.

Sep 1, 2017

Provide d comprehensive source of up-to-date information about technology for revegetating coal mined lands. Approach A great deal of activity and research in the field of coal mine revegetation has been reported in technical literature, both before and after the passage of Public Law 95-87, the Surface Mining Control and Ruclamation Act of 1977 (SMCRA). This information is widely scattered throughout books, scientific journals, periodicals, Government reports, and other sources, and there has been a need to develop a method of accessing it quickly and efficiently. At the request of the Office of Surface Mining Reclamation and Enforcement which promulgates and enforces regulations implementing the act, the Bureau of Mines has prepared a document that identifies literature relevant to coal mine revegetation. Most of the literature available on this subject has been published during the past 15 years. To tap this reservoir of information, 14 data bases were accessed from DIALOG SDI (Selective Dissemination of Information) Service using three keyword combinations (surface mining and reclamation, strip mining and reclamation, and revegetation). This procedure generated over 7,000 listings. The U.S. Department of Energy's ENERGY data base was selected from the 14 DIALOG bases, both for its large number of listings and for its broad coverage of literature. This data base contains all the unclassified information that passes through the Technical Information Center of the Department of Energy, including reports, journal articles, conferences, patents, books, monographs, theses, and engineering materials relating to energy development.

Jan 1, 1986

By Mark Craddock, Johan Swanepoel

In this paper we present The Ultimate Flotation Cell, a newly developed flotation cell that is proving very popular in the industry. All flotation cells have only one purpose and that is the recovery of the required product, the patented impeller and disperser system of the Ultimate Flotation Cell allows total flexibility in order to achieve the optimal recovery. This ability to tune the cell performance provides the optimization of the ?capture? (collection) stage, all existing models address the need for a wide bubble size distribution (100µm-2 mm) to obtain a better flotation size-by-size, Yoon, 1999,Yoon 2000, Franzidis and Manlapig, 1999. The Ultimate Flotation Cell provides flexible performance optimization. This ability to optimize the flotation regime particular to a specific ore is achieved by the following factors: ? The impeller allows vastly improved air induction rates compared to conventional and sparged cells. This ability to induce and disperse large quantities of air, in a controlled manner, allows the cells to be tuned to give the optimal Sb by varying the rotational speed via a VSD which every cell is fitted with. ? The patented impeller gives a very constant and stable air induction rate, which ensures that the cell?s circulation pattern is constant, giving a very stable surface, allowing optimal froth depth. ? Although conventional dart valve, level control can be offered, great success has been achieved with a simple draft tube/sand relief device. ? The cells have a inlet design similar to the old Denver ?Cell-to-Cell? design, which guarantees the at lease one pass through the mixing zone in each cell. Actual plant performance data will be presented from two plants, one in Zambia and the other in the DRC.

Jan 1, 2007

By Hugh Spence

THE use of natural feldspathic rocks, as opposed to straight feldspar, for ceramic purposes is not new. "Cornwall stone," a semi-kaolinized granite containing fluorite, has long been used by the English pottery trade instead of feldspar, and "Carolina stone," a similar rock, is now being offered to the American trade. A recent report of the U. S. Bureau of Mines states that trachyte, a glassy volcanic rock, is being used in California instead of feldspar in ceramic bodies. In Germany, phonolite and basalt have been investigated, and possibly also used, as ceramic raw materials, and extensive research has been conducted in Russia in recent years looking to the utilization of the immense bodies of nepheline syenite of the Kola Peninsula, which is the host rock of the apatite deposits now being exploited on a large scale in the Murmansk region; the nepheline is recovered as a by-product of the concentration of the apatite. Long used principally as a raw material for the pottery and allied industries, where, in bodies, glazes, enamels, etc., it serves as a fluxing ingredient and forms, on firing, a glassy bond with the more refractory clay, flint and coloring particles, feldspar has been finding ever increasing employment in glass. In 1936, over half of the nearly quarter of a million tons of feldspar sold in the United States went to the glass trade. Its usefulness for this purpose is due to the resistance to thermal shock which it imparts to glass products, particularly bottles, containers and tableware, because of its alumina content, which averages from 16 to 20 per cent. Active search has been made on the American continent during the past few years for other minerals of feldspathoid type, with comparable or higher alumina content, that may be suitable for glass and other ceramic purposes. One of the most important results of this work has been the delimiting in central Ontario of large bodies of nepheline syenite of excellent ceramic grade.

Jan 1, 1938

By R H. Knight

Uncertainty in prediction and modelling of geological (physical) ore continuity in geometrically complex ore deposits is a key risk factor in mining. Reducing geometric uncertainty of hard-boundary ore/waste contacts and related geological features improves the efficiency of local mineral resource estimation and reserve calculation, mine/stope planning, ore control and in-mine exploration. Detailed underground mapping of serial-level drives provides a continuous record of the characteristics and contact configuration of ore, as well as crucial ore-related geological features that are required to resolve geometrical variability when closely spaced drilling proves inadequate or is cost-prohibitive. The mapping-based approach described in this paper re-establishes the focus on the geology of the orebody by incorporating high-value, detailed geologic mine mapping information. Mapped ore-related configurations and relationships, recorded on a succession of faces or on a series of levels, provide the basis for 3D interpolation and extrapolation of the local geologic continuity of an orebody. Correlative points representing locations of key ore-related geologic features on each face or level are linked by 3D polylines or trajectories forming a coherent geometrical framework. The coherent progression of geometric changes mapped by these trajectories reveals the overall ‘dynamic’ of the geometrical framework, as well as the spatial tendencies of its geological constituents. Distinct sets of ore control trajectories are selected from within the framework and are used in the construction of alternative geological ore continuity models. As mining proceeds, alternative models are evaluated, and are then either refined or rejected. The geometrical framework is used to evaluate theoretical models and practical heuristics, focus exploration targeting and inform and guide all aspects of mine geology in active mines. This approach also lends itself to analysis of global ore continuity in the re-evaluation of mature or abandoned mines. Its use is particularly effective in geometrically complex orebodies such as the West Branch orebody and the orebodies of No 2 mine of the Balmat-Edwards-Pierrepont zinc district, which are used to illustrate the method. CITATION:Knight, R H, 2014. A mapping-based approach to geological continuity prediction using examples from the Balmat-Edwards-Pierrepont Zinc District, St Lawrence County, New York, USA, in Proceedings Ninth International Mining Geology Conference 2014 , pp 65–76 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By G. E. Wasson

Coal in most refuse ponds including those owned by Consolidation Coal Company can be recovered by froth flotation techniques. Laboratory studies show that the flotation conditions required for coal recovery varied greatly from pond to pond. The variables found to be most important for high coal recovery and low product ash were: a) the amount and type of flotation reagents and b) the degree of conditioning before flotation. Coal recovery at a rate of 0.504 kg/s (2 tons/hr) was demonstrated at a pond site employing a mobile froth flotation unit.

Jan 1, 1988

By Stanley L. Arnot

The Mother Lode district in California is probably better known as the land of Bret Harte and Mark Twain than as a gold-producing district, although in this respect it holds an important place. The history of quartz mining on the Mother Lode dates back to the '50s, when, after the first fever of the gold rush, men began to look for something more permanent, if not more lucrative, than the placers. Since that time, the discoveries, shutdowns, and reopenings of the many mines, together with the varying fortunes of their numerous operators, constitute an interesting chapter in California history, but one too long to include in a description of mining methods. The district is well situated, so far as physical conditions are concerned. The Mother Lode extends along the western slope of the Sierra Nevada Mountains, about half way between the crest and the Sacramento and San Joaquin Valleys, the country traversed consisting of low rolling hills—typical foot-hills. The elevation varies from 1000 to 1800 ft. and the climate is most desirable. There is an abundance of water, timber is easily obtained from the higher foot-hills a few miles east, and cheap hydro-electric power is generated practically on the Lode. These natural conditions are conducive to low costs in mining and have been the deciding factor in allowing profitable exploitation of the comparatively low-grade orebodies. Transportation facilities are not bad. Five branch railroads, from the main trunk lines in the valley, tap the district at intervals of from 10 to 30 miles, and the roads connecting these are fairly good for trucking purposes. Labor is made up of several nationalities, the principal ones being American, Spanish, Jugo-Slav, Italian, and Mexican. There were few Mexicans on the Lode prior to 1919, but the shortage of labor, experienced generally by the mining camps of the country in the years following the war, made necessary the hiring of some. The percentage of Mexican labor rapidly increased in 1920 and for a year or so thereafter, but it has now diminished until at most of the mines only a few Mexicans are working. Of the different nationalities, Americans are the most efficient and Mexicans the least.

Jan 1, 1925

By D Bradshaw

The recovery of molybdenum at Kennecott Utah Copper (KUC) has become increasingly important as its demand and price have risen dramatically in the last few years. Consequently, the flotation behaviour of the molybdenum bearing mineral, molybdenite, has received a significant amount of attention. The flotation performance of molybdenite generally lags that of the copper sulfide minerals and is much more variable. There are many factors including particle size, liberation, surface slimes and oxidation that contribute to this and also much speculation as to the relative contribution of each of these factors. This paper discusses the morphology of the molybdenite found at KUC, the mineral associations in the different lithogical ores types and the effect that each of these has on flotation performance. Quantitative mineralogical analysis and an assessment of particle shapes are used to explain that flotation behaviour does not necessarily follow expected trends and that some behaviour is counter-intuitive. This unique behaviour can be explained by the morphology and anisotropic nature of molybdenite.

Jan 1, 2008

By R. V. Wheeler, F. V. Tideswell

The suggestion, which appears to find increasing favor, that the elementary composition of coals should be used as the basis of their classification, makes it important that our methods of expressing this elementary composition should be refined. It is doubtful whether many published ultimate analyses of coals are accurate within 1 per cent. carbon. Many are probably as much as 3 or 2 per cent. in error in carbon. It is, perhaps, not always realized that the extreme variation in carbon content over the range of bituminous coals is but 16 per cent. An error of 1 per cent. in carbon on analysis corresponds therefore with one-sixteenth of the whole range, an amount which is unjustifiable even for the application to commercial needs of a system of classification based on ultimate analysis. For the purposes of scientific research such limited accuracy is of little value. The object of this paper is to examine one important source of error in ultimate analysis, that due to the occurrence in coal of inorganic material, and to emphasize the need for the quantitative measurements (of carbon more particularly) on coals to be rendered independent of their contents of such material. Adventitious Mineral Matter When a determination of calorific value, for example, is made upon a coal, it is customary to correct the measured value with respect to the ash left by the coal on incineration, recording the result as being on an "ash-free basis." It is desirable, before discussing the adequacy of the correction thus made, to demonstrate its validity, which turns on whether the ash is present as an adventitious impurity in the coal and forms no part of the coal substance itself. The inorganic matter associated with coal has originated in several ways1: 1. The "inherent" inorganic materials, occurring as constituents of the plants from which the coal-forming deposits were derived.

Jan 1, 1928

Jan 1, 1924

Jan 1, 1924