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By R. Hogg, T. F. Dumm, L. G. Austin, M. Yekeler

"Dedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayAbstractThe kinetics of batch grinding quartz from a feed of 600 by 425 Jim to a product of 80% less than 10 µm have been determined using screening and laser diffractometer sizing for size analysis. The specific rates of breakage decreased by a factor of about three when the material became less than about 100 µm in size, but the primary breakage distribution function also changed to give proponionately more fine material, so that the grinding efficiency expressed as the development of surface area (B.E:T.) per unit of energy input did not decrease. Analysis of the shape of the particles in the 2S x 38 µm size range showed that particles of this size produced by roll crushing or by 8 minutes of grinding of a 42S x 600 µm feed were not different but at long grinding times the particles were rounded. This suggests that the breakage mechanism changes to give more chipping and abrasion and less disintegrative fracture. As the material approached the ultrafine size range it adhered to the mill case and there was no further size reduction. However, a technique for striking the mill case to dislodge the particles was successful in allowing further grinding to 400Jo by weight less than 2 µm.1 IntroductionIt has long been known that it is difficult to accomplish ultrafme grinding in a tumbling ball mill. It has been reported [12, 13] that there is no further size reduction after some hours of grinding cement clinker in laboratory ball mills. Austin and Bagga (1] and Shah and Austin [16] have given an analysis of the kinetics of dry grinding in a laboratory ball mill, introducing the concept of a slowing-down factor K, which is the ratio of the specific rates of breakage at some long time of grinding to the normal specific rates of breakage. They showed that this factor decreased as fine material accumulated in the mill charge. Cottaar and co-workers [8-10] showed that the movement of solid in a dry laboratory ball mill was influenced by the fineness of the solid and by the presence of air, and that evacuation of air from the mill caused particle sedimentation and low rates of breakage.The concept of the slowing-down factor has also been used in wet grinding [17, 18]. At very .high slurry concentrations it appears to be correlated with a steady decrease of mill power caused by the build up of a layer of deposit sticking to the mill case. This reduces the effective mill diameter and, eventually, the balls start to adhere in the layer and centrifuge. A decrease of mill power always indicates less lifting and tumbling of the media and, hence, less breakage. However, slowing-down of breakage rates was also observed at lower slurry concentrations where there was no change in mill power."

Jan 1, 1990

By J. W. Butwell

Anaconda has been active In the Bingham mining district near Tooele, Utah since 1914 when the company acquired International Smelting & Refining Co. Over the years both custom ores and complex Pb-Zn-Cu ores from the district were milled and smelted at International. In 1948 Anaconda acquired the property that covers the present Carr Fork ore body. Since that time active exploration took place in the 50's followed by detailed geological evaluation in the 60's. Convinced that high grade Cu deposits would be found at depth, a deep drilling program commenced in the late 60?s, with intersection of the ore zone in 1969. Following extensive deep drilling in the early 70?s, a feasibility study was conducted in 73-74 with board approval given Sept. 6, 1974. The 9,000 t/d mine-mill complex was budgeted at $217 MM over a 5 year schedule with start-up in Sept., 1979. The following discussion includes the concentrator and surface facility portion of the budget or approximately $60 MM of the scope. Special emphasis will be made on equipment selection and layout.

Jan 1, 1980

By C. H. Fisher

[Mxny methnhs of ,analyzing tpr oils fnr thoir tar acid ~nd base cnntent hava boon employL~d in connection mith both ac~d,.mic and. industrial investigs- tions. Mnst of thznu nnalyticel proc?durn~s aro bpsed nn th; diminution in volums caused by extract lon sit5 alkali 5 minL+ra,l acids (cantrsction rn,>thod) , although othrr mr~thrids havu &apos;sL<on ?q~lnglt 8 . In many instmccs th-: donti ti on of RT~ m~lytic~l m ithod was not ;r.:c ~d~d by ~d.jqunt9 study, and, ns 3 cone+ qucnce, tha lit .,ratur ? on thls sub,jr:.ct is consoScuous for its cnntr~dictnry . claims and rocnmmondatinna.. 1.t tiR.s b9~n shoyn in th;, cnsn of c.lrtn.in synth?tic solut innsfi/ thnt larg~ jr-orn sny rcsult if th2 ,mnlysis is c~rri~d out by sim~la extraction wi.th alidi r.nd min 3rd ncids.]

Jan 1, 1937

By Augustus Locke

The paper has two parts: the field argument and the microscopic argument. The field argument indicates that either the deep chalcocite has replacea sulfide of extraordinarily easy replaceability or it is hypogene. The microscopic argumentindicates that this sulfide, if it existed, must have been hypogene bornite; that this bornite must so excel known bornite in replaceability as to constitute a new variety; that the existence of this new variety is wholly unsupported by evidence; and that the deep Butte chalcocite is therefore hypogene. IN 1900, when the public first heard of "secondary enrichment" the Butte chalcocite seemed clearly supergene. Mining, through successive regions of leached capping, bonanza sulfide, and sulfide less rich, had paused at lean bottom levels which, though chalcocite-bearing, suggested the waning of copper. The deepest chalcocite, at 1500 ft., was yet too shallow to disturb the supergene hypothesis. But, with deeper mining, lean levels yielded to fat ones. Here and there they showed, within the same vein, an inverted distribution, chalcopyrite above and chalcocite below. To the miners&apos; astonishment, they carried chalcocite, unaffected by cross faults, on an independent course to the depth of 2500 ft. The pattern of ore distribution, hitherto revealed only in fragments, was now appearing in perspective, and, in the depth of the chalcocite, was beginning to make Butte differ from all districts where the chalcocite is indubitably supergene. The idea of hypogene origin at length came into favor; by 1913, when Sales1 advocated this origin, the argument had become a powerful one. This argument rested on field evidence; but, already, there was beginning to emerge microscopic evidence not included in this arugment. Especially pertinent was the proof that (1) The deep chalcocite lies in-mixed with bornite, often microscopic; (2) the deep chalcocite often replaces bornite; and (3) replacement of bornite by chalcocite is accom-

Jan 3, 1924

By T. Field, N. D. Nxumalo

Since the discovery of gold on the Witwatersrand in 1886, mining has been at the centre of South Africa’s development. Although mining continues to contribute significantly to the country’s economy, it is a temporary land-use activity, and mine closure is inevitable. This paper reviews mine closure planning at Tshikondeni coal mine, which commenced in 2014 with the initiation of mine closure. The review presents the mine closure processes undertaken at the Tshikondeni coal mine as regulated by South Africa’s principal mining legislation, the Mineral and Petroleum Resources Development Act 28 of 2002, and other relevant regulatory frameworks. To compile this review: (1) A desktop study was conducted; (2) empirical data was collected through one-on-one interviews with research participants at Tshikondeni coal mine; and 3) physical observations were made of the rehabilitation at various mine operations within the Tshikondeni coal mine complex. Research participants consisted of mine officials from different departments, i.e., human resources, and environmental, social, and business strategy, who were directly involved with the Tshikondeni coal mine closure. A questionnaire with semi-structured questions was developed. It was utilised to acquire a better understanding of mine closure planning at Tshikondeni coal mine and identify mine closure processes that aim to achieve post-mining land uses and align with Tshikondeni coal mine’s post-closure strategy, namely the Tshikondeni Legacy Project, with a post-closure strategy that has the potential to transition a mining economy to an eco-tourism economy that can preserve livelihoods and selfreliant communities.

Dec 15, 2025

By Robert B. Parsons

"Canada doesn&apos;t really have a tax system for mining - it has eleven separate tax systems! The consequent maze adds some undefinable margin of difficulty to making investment decisions in Canada. But, this 11U1Ze is not likely to be simplified. Solution: learn it and sell it! Intricate Network of Winding PathwaysWebster&apos;s New World Dictionary defines the word ""maze"" as follows: ""a confusing, intricate network of winding pathways; labyrinth ... a state of confusion or bewilderment"". Webster&apos;s does not go on to give an example of a maze, but the dictionary could easily have referred to the taxation of a Canadian mining operation. The uninitiated would almost certainly look upon such taxation as a maze of the most perplexing sort.Twenty years ago, Canada&apos;s tax system was really quite simple. It is true that Canadian mining profits were subject to three levels of taxation (federal income tax, provincial income tax, and provincial mining tax), but this didn&apos;t pose a problem. Prior to 1974, at least the provincial income tax systems were somewhat the same in terms of rules .and rates, and even the provincial mining tax systems resembled one another. Mining profits were subject to pretty much the same rules, no matter what province or territory hosted the mine. Those were the “good old days” one could even dare to generalize about tax rates without fear of being labelled an imbecile!"

Jan 1, 1994

By Robert Strachanm

The East Kootenay coal-field, situated close to the boundary between the provinces of Alberta and British Columbia, is composed of four small areas locally called the Crow&apos;s Nest Pass, the Upper Elk, the Flathead and Crown Mountain, and comprises an area of about 3 78 square miles. From eleven to twenty-five seams have been exposed of two feet and over in thickness, with a total thickness of about 200 feet of coal, and reckoning about one hundred feet to be workable, gives an estimate of coal available of about thirty-seven billion tons. The coal is a high-grade bituminous, occasionally tending towards anthracite, and the majority of the seams furnish a. very good quality of coking coal as well as an excellent steam coal. The coal-field is found in the mountain ranges in long narrow strips. The age of the fonnation and the thickness of the covering beds have had considerable influence on the character of the coal, and lateral pressure and disturbances in the process of mountain-building have wrought great changes. With such an abundance of coal, it has been a disappointment that the East Kootenay field has not figured larger industrially. So far only one portion of the coal-field has been utilized. This is the Crow&apos;s Nest, where, in 1898, the Crow&apos;s Nest Pass Coal Company commenced development. Access to the coal seams was easily obtained, the mountain creeks having eroded away the covering, and mines were driven into the coal seams. In that year about ten thousand tons of coal were produced from the mine at Coal Creek.

Jan 1, 1924

By Fulton B. Flick

The micrography and macrography of aluminum and its alloys present certain difficulties. Many of the difficulties attendant on the micrography have been removed by methods developed during the past few years, notably those of E. H. Dix, Jr.1 The development of grain size in aluminum and its alloys may be equally troublesome, yet comparatively little detailed attention appears to have been given to it. Satisfactory reagents are available for the development of such structurcs in ferrous and most non-ferrous metals, but those applied to aluminum and its alloys, i. e., alcoholic or aqueous solutions of sodium hydroxide or hydrofluoric acid are not entirely satisfactory. Hanson and Arch-butt,2 in speaking of these two reagents, state that "These two reagents give fairly satisfactory results, but they sometimes produce badly tarnished surfaces from which the surface deposit is difficult to remove." It has been our experience that neither of these reagents is to be entirely relied on for developing structures suitable for study or photography. This means that when the etch fails to produce satisfactory results the specimen must be repolished, through the 000-paper at least, and then etched with another reagent. This procedure entails a considerable loss of time, and the final results may not be all that might be desired. However, the reagent to be described, although not a panacea for all etching troubles, has improved results so markedly that it is felt that it & worth offering as a grain-size etch generally applicable to aluminum and aluminum alloys. Czochralski3 in 1915 mentioned the application of a solution of 10 to 20 c. c. concentrated hydrofluoric acid in 100 c. c. absolute alcohol, etching in this reagent being followed by dipping in concentrated hydrochloric acid soliltion.

Jan 1, 1925

By D. L. Ritter, N. J. Grant, B. C. Giessen

Forty-six alloys covering the complete concentration range of the Nb-Rh system were examined by metallographic and X-ray methods; solubility limits of terminal ad intermediate phases and transformation and solidus temperatures were determined. There are nine intermediate phases; two eutectic, five peritectic, two eutectoid, and three peritectnid reactions were encountered. The experimental methods and the constitution diagram are described in Part I. Part 11 deals with the crys -tallography and relation of the intermediate phases. The Nb-Rh system was selected for study for three reasons: first, it was hoped that the anticipated similarity of the Nb-Rh phase diagram to the Ta-Rh1 and Ta-Ir2 diagrams treated earlier (see also Ref. 3) and to the Nb-1r4 diagram treated simultaneously would allow a crystallographic and comparative evaluation of the intermediate phases in these related systems; second, it was likely that the previous experimental methods could be carried over without significant change; and third, it was expected that the interesting mechanical properties of the a1 phase of the Ta-Rh and Ta-Ir systems would also be encountered in similar phases of the new systems, and that these phases could be investigated more closely. The phase diagram had not been treated fully in the literature; only brief surveys of some intermediate phases were found.5-7 It was attempted to cover the details of the phase boundaries, Part I, as well as to present the crystallography of the intermediate phases, Part 11. EXPERIMENTAL METHODS Specimen Preparation and Treatment. The following high-purity starting materials were used. 1) Niobium powder, 99.8 pct pure, mesh size -60 +200, from Wah Chang Corp., Albany, Ore. The analysis furnished by the supplier showed the following major impurities: Ta, <500 ppm; Zr, <500 ppm; 0, 300 ppm; Fe, 280 ppm; Ti, <I50 ppm; W, Si, <100 ppm; C, N, 30 ppm; all other impurities, <30 ppm. 2) Rhodium powder, ground sponge, 99.9+ pct pure, mesh size -80, from J. Bishop Co., Malvern,

Jan 1, 1964

The Hunter Valley Rail Project (HVRP) represents most of the coal producers using the Hunter Valley Rail System in NSW to haul coal to the port of Newcastle. This system carries over 70 per cent of NSW&apos;s coal exports, comprising over 30 per cent of total Australian coal exports. Hunter Valley coal is the largest export industry in NSW, and one of its largest export growth opportunities. However, the industry is under intense pressure in international markets from existing and new coal producers and from other energy sources. Whilst potential growth in demand is substantial, particularly for thermal coal in Asia, excess world supply has pushed prices down, and this underlying trend may well continue. The industry has lost international competitiveness and as a result, investment has dropped 44 per cent over the last two years. The industry must be rapidly structured to compete and attract investment on the basis that these pressures will continue. Substantial productivity improvement and cost reductions must be made for the industry to regain competitiveness, otherwise growth will not occur and the industry will decline, with serious implications for the Australian and NSW communities. The introduction of internationally competitive rail freight rates is an urgent and essential part of this process. It is the key objective of the HVRP.

Jan 1, 1995

By M. J. Deats

INTRODUCTION To prepare the reader adequately, reference should be made to the paper &apos;The Pioneering of Fully Mechanized Longwall Coal Mining in South Africa&apos; by R. T. Naude and M. J. Deats, published in the February, 1967, edition of the Journal. At the time mechanized longwalling had been proved operationally feasible with encouraging results since its inception in South Africa in mid 1965. Subsequently, further top seam panels were successfully extracted with improved productivity and with some modification to equipment. In 1968, after an overseas visit by mine officials, equipment specific to suit local conditions was acquired and lower seam trials commenced. Despite initial obstacles and difficulties the first panel was successfully mined. Modification and improvements to equipment and techniques resulted in the second lower seam panel being extracted economically during 1969-1970 and with productivity exceeding even that of top seam faces. During extraction of the second lower seam panel, gradual and complete surface subsidence occurred over the panel without affecting face operations. Rock mechanics investigations had originally indicated some uncertainty regarding adverse dolerite sill behaviour which could have caused longwall mining to be hazardous. All such doubts have now been removed. RESUMÉ AS AT FEBRUARY, 1967 Mechanized longwalling was introduced in 1965 on an experimental basis in an effort to improve productivity in the newer area of the mine and to increase the quality of the comparatively dirty run of mine feed to the washing plant. In addition advantages could be predicted in the long term by better utilizing reserves of straight coking coal and increasing the life of the mine. The top seam unit was obtained on a rental basis and by the beginning of 1967, two panels, the first having a face length of 215 m, a panel length of 345 m, seam section of 1 219 mm, and the second the same face length, a panel length of 453 m and a seam section of 1 067 mm had been successfully longwalled. At this stage a best month of 24 602 metric tons with an average of 17 364 metric tons per full working month could be reported. Results were sufficiently encouraging for the company to exercise its right to acquire the equipment as its own asset and from 1967 onward, the unit has operated on this basis. From the point of view of rock mechanics, the dolerite sill over the first two panels was known to have &apos;bridged&apos;, only the material below the base of the sill having truly &apos;goafed&apos;. No adverse pressure effects had significantly affected face operations except for two &apos;bumps&apos; towards the end of operations in each panel. Gate road maintenance presented no problem. The strong inflows of water experienced on the first face were now known to be associated with an isolated water bearing fault plane and were not experienced on the second face. TOP SEAM EXPERIENCE - MAY, 1966, TO DATE Panel 2 (February, 1966, to November, 1966) The operations in panel 2 (see Fig. 1 for location of panels) continued uneventfully until the final month in this panel. At this stage, the chocks behaved most inconsistently often lowering under the weight of the canopies alone. Roof trouble became so severe that the unit was unable to produce adequately and blasting of chocks became a daily occurrence. Finally 24 m short of the planned limit it was decided that a complete overhaul was the only solution and the extraction operations commenced. At this time, the only fatal accident associated with longwalling occurred when a Non-White inadvertently fell into the panzer conveyor transfer point at the main gate. Some gate road difficulties in this panel were overcome by bolting tapes to the roof as decking and allowing them to pass over the gate chocks and collapse into the goaf. Two cribbed roof falls were also negotiated by the gate chocks at the face ends without undue difficulties. It was decided in the light of maintenance problems encountered on this face that the best solution would be to appoint a foreman solely in charge of face maintenance crews. This step has to a large extent contributed to success achieved subsequently. Panel 2-face length 213 m panel length 456 m cutting height 1 092 mm average monthly output 16 443 t best month 19 130 t Panel 3 (December, 1966, to June, 1967) By the end of 1966 results were sufficiently encouraging for the company to exercise its right to acquire the equipment. This was negotiated and the unit has operated as such to the present date. Prior to installation in panel 3, all face equipment was thoroughly overhauled underground and the chocks boost-tested to yield-load. The costs of overhauling, including almost complete hose replacement, were much higher than anticipated. Advice had been received that complete hose replacement was common practice after +/- 18 months&apos; operation. Shortly after commencement of operations in panel 3 the chocks again failed as they had towards the end of panel 2. At this stage, the suppliers advised that the valve gear should have been repaired during the overhaul as the needle and seat seals could no longer be relied upon. This operation was impossible to carry out on the face and would have been e1ttremely time consuming. Fortunately a new type of valve gear was then available from the suppliers, termed the capsule-type valve, and a complete change over could be made on the face. The encapsulated valve has a delrin pad sealing over a raised

The control objectives and constraints for grinding circuits are ana- lysed, taking a single-stage ballmill-cyclone circuit as an example. The design of a hierarchical modular control system is described, for implemen- tation on modern microprocessor-based control systems. Product sizing measurement is identified as a problem area, and a new approach to product sizing inference, from on-line cyclone feed and overflow measure- ments, is presented. The procedure over-comes several practical difficulties of a previously proposed inferential method and is therefore expected to find application in more advanced grinding circuit control systems.

Jan 1, 1988

By G. L. Oldright

NEARLY all of the present schemes for treating complex (i. e. lead¬silver-zinc-copper) ores are based on the idea that lead holds, and will hold for some time, the strongest economic place from the viewpoint of supply and demand of all the non-ferrous metals. Copper, it is thought, will come back to its own when European affairs are stabilized, although at that time competition from Chile, Peru, and Katanga, in particular, will be more severe than in pre-war days. The future for silver and for zinc is uncertain. New uses are developing for zinc, and the market has remained better than many expected, but the stabilization of world markets will bring in foreign competition instead of relief. The cost of producing zinc from simple zinc ores, by the retort process, will, from the nature of the labor required and the increasing cost of fuel, increase steadily. As a result, the small producers of purely zinc ores around Joplin are shutting down their mines, even with a good market price for zinc; on the other hand, the producer of lead from complex ores, in the Rocky Mountain states, is confident of a profit from the sale of his lead, and is seeking means to make the zinc in his ore pay some part of the cost of treatment. However, the tonnage costs for mining and ore dressing are much higher in the Rocky Mountain states, as may be seen by comparing tax-return statements from the various states. Even before the recent drop in the price of silver, many mines were operating on a very slender margin of profit; labor and supplies cost more. Mining at greater depth has shown most orebodies to grow increasingly more complex, so that improvements in mining and ore-dressing practice have not been sufficient too compensate for the additional expense involved in beneficiating these ores. The smelters have had to meet the same general economic situation, so they can only give

Jan 3, 1924

By AIME AIME

THE coal classification session* on Monday morning, Feb. 17, was opened by a paper by M. R. Campbell, entitled "Natural Groups of Coal and Allied Fuels," in which he pointed out, by means of graphical presentation of selected proximate analyses of coal, that coals can be classified on the basis of their moisture content. He proposes four groups of coal, brown coal, hydrobituminous, bituminous, and anthracite, each subdivided into two or three sub-groups. In a written discussion of this G. H. Cady, of the Illinois Geological Survey, showed that there is, in general, a progressive decrease in the moisture of Illinois coals from north to south, and that it would be very difficult to draw any arbitrary line dividing the coals of the State into two groups on the basis of moisture content.

Jan 1, 1930

By G. T. Jackson

The Alaska Gastineau Mining Co.&apos;s mine is located at Perseverance, about 4 mi. east of Juheau, Alaska. Its property consists of a group of claims, the lode system traversing these claims for a distance of 11,000 ft. (3352 m.). It is shown in Fig. 1. The ore deposits occur in what is known as the Juneau gold belt. This gold belt can be traced for about 50 mi. northwest of Juneau and 40 mi. southeast. It consists of a single band, several hundred feet wide, in which stringers and veins of quartz, carrying gold, occur in a slate formation near its contact with some altered volcanic rock known as greenstone. The Perseverance orebody consists of stringer lodes, having a strike northwest and southeast, dipping about 60° to the northeast. These

Jan 1, 1920

By J. A. Taylor, H. F. Yancey

"INTRODUCTION Froth flotation as applied to coal is a process for separating desirable carbonaceous material from undesirable inorganic matter. In general, the feed must be finer than one eighth inch in size. The principal use of the process in the preparation of coal appears to be in the treatment of the fine sizes produced by breakage during mining and preparation.The Bureau of Vines in Information Circular 6714 has published general information on coal flotation, summarized investigative studies of the process, and described operating plants throughout the world with their tonnage, reagent consumption and operating costs.4ACKNOWLEDGMENTSThe present study of means for depressing pyrite and reducing ash ty froth flotation was conducted at the Northwest Experiment Station of the United States Bureau of Wines in cooperation with the College of vines. University of Washington, under the general direction of A. C. Fieldner, chief engineer, Experiment Stations Division, Bureau of Wines. Grateful acknowledgment is made for suggestions and criticisms received from W. H. Coghill, supervising engineer, U.S. Bureau of Mines Mississippi Valley Experiment Station, Rolla, Mo.; J. B. Morrow, and R. E. Zimmerman, of the Pittsburgh Coal Co.; and Dean Milnor Roberts and Prof. Joseph Daniels, of the College of Mines, University of Washington.FLOTATION AND DEPRESSIONA substance will tend to float if its surface attracts a gas film more strongly than it does a liquid film when both air and liquid are competing for this attraction. On the other hand, a substance will not float if its surface attracts a liquid film more strongly than it does a gas film. All theories of depression depend upon this fact. A wetted particle of floatable size most likely will be found in the tailings after the flotation process has been completed.The crux of flotation is the selective wetting of the undesirable material that tends to float. Two general methods 5, 6, 7 of depression are in use: One combines a chemical substance with the surface to form a wettable compound, and the other employs some colloidal or ionic substance which the surface selectively adsorbs, thereby forming a wettable surface."

Jan 1, 1935

By K. Kiangi

On installing the Metso Superior MK 54x75? primary gyratory crusher in Nkomati mine the crusher experienced severe power spikes greater than 1000kW which subsequently led to the crusher tripping under load while processing some of Nkomati?s MMZ ores. Likewise significant losses in throughput were also experienced while processing some of Nkomati?s MMZ ore types. Interestingly the crusher was capable of processing the PCMZ ores without experiencing any power spikes or losses in throughput. Investigations into the challenges faced by the crusher while processing Nkomati?s MMZ ores were conducted using the DEM model in conjunction with the fast breakage model present in Metso?s High Fidelity Simulator. The intentions of the study were to establish the most suitable operating conditions or cavity design that would potentially enhance the performance of the crusher. Likewise an understanding of the effects the feed conditions (size distribution and hardness) had on the crusher?s performance was established. Ore characterization tests were conducted on Nkomati?sPyroxenite, Diabase, Calc silicate and quartzite ores which were from Nkomati?s MMZ ore body. The ore characterization tests conducted were drop weight tests, slow compression tests and elastic modulus tests. Four simulations were conducted used the existing cavity design with various open side settings (OSS) and throws. This established the effects of changing the crusher?s operating conditions on its performance. Four additional simulations were conducted on two cavity designs with reduced volumes. This established the effects of changing the crusher?s cavity design on the crusher?s performance. Thus through the simulations a better understandings of the impact of the crusher design, operating conditions and feed conditions on the crushers performance. Furthermore an analysis of the crusher?s performance was made which was used as a basis for comparisons with the base case simulation. Keywords: crusher, discrete element method, simulation, ore characterization

Sep 1, 2012

By H. P. Dibbs

An account is given of the application of neutron activation analysis to the rapid, non-destructive determination of copper in minerals, using a 14-MeV neutron source. Elements that interfere in the determination of copper by this method are given, together with the errors in the estimation of copper that result from the presence of varying amounts of these elements. The possible use of a compact "sealed-tube" 14-MeV neutron generator for the field assay of copper in minerals is discussed.

Jan 1, 1970

By H. Y. Yancey, B. M. Bird

During the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin arid washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing. Basis for Use oF Hindered-settling Classification of Table Feed Although theoretical reasoning might be used to justify treating a table feed by hindered-settling classification,l the simplest method of demonstrating the need of such a step before tabling is to show the

Jan 1, 1930

By Franziska Günther, Helmut Mischo

The calculation of costs for an underground mine, as well as the planning of the equipment and materials to be used, is a complex and time-consuming process. The estimation depends on a multitude of parameters, and all mining processes are interconnected. A novel tool has been developed that enables automated calculation of underground mines and allows for the comparison of the effects of changing individual parameters. Previously, changing individual planning parameters often necessitated a complete recalculation of the mine. The newly developed calculation tool provides an innovative planning aid that allows for more efficient and accurate mine planning and cost estimation. The tool enables the user to implement continuously up-to-data costs and prices. This allows for more accurate planning data and results. The underlying concept of the calculation tool, its implementation at a planned quartz porphyry mine in Germany, and the verification of the tool at an existing underground mine will be presented.

Feb 1, 2025