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By V. Karra

Based on extensive investigations on the effect of design variables on process performance, during 1982-85, Nordberg developed a 1000 hp cone crusher, with the objective of boosting crushing productivity in existing plants. The 2390 fits on the same foundation as the 7' SHD Symons cone, but is designed to give two times the capacity of the 7'. The economies of scale involved give the customer substantial cost savings. In this paper process performance of the Nordberg 2390 relative to the 7' SHD Symons cone, while crushing the same ore, will be presented. Also, implications of such a crusher scale-up to associated cost savings will be addressed.

Jan 1, 1988

By R. N. Guest

The Tromp distribution curve was used in an evaluation of gravity separators treating a synthetic ore made up of silica and marker minerals of various relative densities. The results pinpoint differences in the concentration of particles of different sizes, and indicate how the grade of a concentrate is likely to vary with particle size. An increase in the feed rate increased the efficiency of the 'waterless' spiral concentrator that was tested, but the multiport spiral concentrator tested was more efficient. Both spiral concentrators were found to be more efficient than the pinched sluice and the shaking table that were tested. The method was found to be a useful way of evaluating gravity concentrators, but, for ease of analysis, care must be taken in the choice of marker minerals.

Jan 1, 1985

By H. Landsberg

SUBSIDENCE caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian Committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a pre-liminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem.

Jan 1, 1936

By D. J. R. Ras

A sub-level open stoping method is being used to mine the massive deposits at TARGET Gold Mine which uses cemented tailings to backfill the stopes. This requires the construction of bulkheads to contain the freshly placed backfill, capable of resisting the hydraulic pressure imposed by filling. The bulkheads must contain an 8 metre head of backfill slurry within 48 hours and withstand the force exerted by a 35 metre load of consolidated fill at a maximum estimated fill relative density of 1.9. After a variety of methods of construction were evaluated, it was decided to construct the bulkheads using the low density, fast-setting foamed cement-based product TEKSEAL HS manufactured by MINOVA RSA. The cement foam is contained between low-cost steel and fabric brattices which are easy to construct, using a method specially developed for the TARGET bulkheads. The paper will describe the design, trialling and construction of the bulkheads, and results obtained to date.

May 1, 2007

By Jeff Wachendorf

Due to the competitive nature of the coal industry we are constantly challenged to reduce costs associated with day to day operations. Every facet of the mining operation is scrutinized for cost reduction and possible efficiency increases. This paper will discuss the pros and cons of two different blasting methods. Buffer blasting has been an institution for many years at Spring Creek Coal and very successful in its application. Cast blasting arrived on a trial basis in 1998 and has produced very encouraging results. This paper will describe the design, drilling, and blasting methods currently used, and a comparison of these two methods.

Jan 1, 2001

By F. G. Loper

Simulation as a mathematical technique is not new. However, recent increases in digital computer speeds and the ease of programming with languages such as Fortran have centered a good deal of attention around simulation in the last few years. By ignoring all but the relevant characteristics of a process, a mathematical simulator may be constructed which, when fed operating data, should react as the process would. The output becomes numbers, instead of tons, however. Thus, a trial-and-error operation of such a simulator will permit management to study a major system change at little cost.

Jan 1, 1967

By Ole Singstad

The legislatures of New York and New Jersey, determined in 1919 that a vehicular tunnel should be built under the Hudson River. On July 1, 1919, an engineering staff was organized with the late Clifford M. Holland as chief engineer. After preliminary investigation it was decided to build the tunnel from Canal St., New York, to 12th St., Jersey City, which is the center of the heaviest traffic across the Hudson River. It was also decided to build two tunnels—one for west-bound traffic and one for east-bound—the tunnels to be of cast iron, built up of segments and bolted together, each tunnel to have a roadway 20 ft. wide and a clear head room of 13 ft. 6 in. The tunnels have an exterior diameter of 29 ft. 6 in. The interior lining is of concrete, the sidewalls, tiled with a vitreous white tile, and the roadways are paved with granite block. The entrances and exits at both ends are separated by two blocks so as to reduce traffic congestion. Basis of Ventilation It was recognized very early that one of the most important problems confronting the engineers was a proper ventilation system. It was estimated that each tunnel as planned would have a traffic capacity of 1900 vehicles per hr. The tunnels are 8500 ft. long between portals, and it was considered that the ventilation should be based on all of these vehicles being operated by gasoline engines. That presented a problem in ventilation unlike any other either in magnitude or character. There have been vehicular tunnels built in Europe, principally in London, but they are shorter and have a smaller traffic capacity. Up to the present time, at least, they have handled a very large percentage of horsedrawn vehicles so that the necessary ventilation has been provided for by the natural draft through the portals and open shafts. Within the last few years, however, a small mechanical ventilating plant has been installed in the Blackwall Tunnel, which has been in operation about 27 years. I might mention that at the time this work was started, it was considered by many that the problem of ventilation was insuperable and it

Jan 1, 1927

By Thomas L. J

A series of tests on rock stress measurement devices used with the overcoring method indicated that improvements could be made in their construction. A prototype inclusion cell was developed with strain gauge rosettes bonded to a 0.05 mm thickness stainless steel sheet which was formed into a cylinder around two end pieces. The finished diameter was slightly larger than previous cells so that the thinner plate and the reduced annulus of Araldite cement in the installation borehole gave a better response in the laboratory than the other cells tested, especially in simulated bedded rock. It was less affected by inhomogeneity and temperature changes. Its high sensitivity should make it suitable for both absolute stress measurement and field monitoring. A table of comparative readings is given for the new cell and for four other devices used in simulated in-situ rock conditions.

Jan 1, 1992

Agenda ?Introduction ?Geology ?Mining ?Metallurgy ?Process, Layout ?Environmental Background ?Kinross Gold Corporation owns the Lobo-Marte gold property, located in Region III of northern Chile. ?The property is close to two other Kinross mines, Maricunga 50kmto the south and La Coipa 60km to the north, plus a regional office in Copiapo and district level operating synergies are expected. ?Lobo and Marte were discovered in the early 1980s and are intrusion-hosted, porphyry-type precious metal deposits, typical of the Maricunga District. ?The Marte open pit heap leach mine was in commercial production in late 1988, but was suspended in February 1992 as it did not meet forecasted production levels and recoveries. ?Kinross plans to recover ore from the Lobo and Marte deposits through an open-pit, heap leach47,000tonne per day operation.

May 1, 2010

By Richard H. Terhune

Slag and matte, in lead and copper smelting, are, for convenience of removal, tapped into pots of small capacity, usually of paraboloid form, of cast-iron, weighing 275 to 300 pounds, and holding the same weight of slag. As in many smelting districts one ton of ore makes a ton and a quarter of slag, a large number of pots is needed to equip an ordinary plant. Sudden and frequent expansion of the solid bowl causes the pots to crack at the bottom in a few months, and the matte, a very fluid sulpliide, enters these rough fissures and speedily corrodes its way through the vessel. 1 find, from one year of practice with a slag-

Jan 1, 1887

By David L. Moffatt, Leon Peters

A unique electromagnetic pulse sounding system for the detection and identification of geological and man-made anomalies which represent hazards in hard rock rapid tunneling operations is described. The main features of the system including a periodic video-type pulse interrogating signal and a probe structure that permits operational modes which either "see" or are "blind" to homogeneous-type targets are reviewed. The results of experimental pulse measurements on targets buried in the overburden and in a limestone medium are presented. Since the electrical properties of limestone are not radically different from those of a hard rock medium, conclusions based on these data should be valid for a hard rock media also.

Jan 1, 1997

By S. Barkhoudarian, R. R. Gupta, R. F. Steinberg

A study of the feasibility of using acoustic signals to detect discontinuities ahead of excavation has shown that reflecting interfaces in a homogeneous rock can be easily identified. Moreover, discontinuity interfaces in a very complex field site (where the rock face was weathered, was full of jointed rocks, and had a destressed zone running along the mine walls) could be identified with a reasonable level of confidence, using a cross-correlation technique for signal processing. The results of this study go a long way toward proving the feasibility of the technique. However, further development work is needed to optimize an operating system in a hard rock environment where boring machines are used for excavation.

Jan 1, 1997

By Rex T. Ellington

The fluidized bed is an effective method for investigating retorting phenomena and possibly a commercial means of retorting oil shale. Both were examined by Sinclair Oil (now part of Atlantic Richfield Co.) in the period 1965-1698. The results of the work show that the presence of an oxidizing environment during retorting results in loss of oil yield which indicates that vapor phase oil burns in preference to combustion of coke on spent shale. Consideration of hardware indicates that there are several possibilities for commercial embodiment. As a companion to shaft-type retorts the fluidized bed could have good potential. Realistic assessment of costs suggests that further development may have to wait commercialization of another process.

Jan 1, 1974

By Hendrix J. L, Nelson J. H

A model based on non-steady state has been developed for dissolution and diffusion in porous ore particles. Results from the particular model have been incorporated, as a rate term, into a global, heap-scale model based on a plug flow reactor at unsteady state. The global model can be used to consider leaching by aqueous-phase reagents in equilibrium with a gas- phase component, such as oxygen gas, as well as strictly aqueous-phase reagents, such as cyanide. The flexibility of the model even allows predic- tion of the outcomes of using reagent sideflow injection in large heaps. Data from column leaching tests are compared to the model, and their relationship is discussed.

Jan 1, 1991

By Daziel M, Corke P

Unit cycles in mining have not changed for many years. Productivity increases over the past three decades have mainly been achieved by using larger and heavier machines. This investment in size has probably reached the point of diminishing returns and increased productivity in the future will have to be generated by other means. One way of achieving this is through automation of selected unit operations, eg dragline overburden removal, truck haulage, ground support installation and secondary breakage. Although, in the past few years, there has been significant progress in this direction, we are still a long way away from even partial automation - especially in hard rock mines. This paper addresses the technical obstacles facing mining automation; suggests ways by which these obstacles may be overcome and identifies the role of industry groups and research providers in this process.

Jan 1, 1997

By Watt KL

Chemical anchors for use in rock bolting have been produced in Australia under licence for several years. These anchors are alternatives to the more normally used mechanical anchors and give improved anchorage strengths under some conditions, although at greater cost. Considerable development during this time has resulted in an improved sausage-type chemical anchor more competitive in price, to such an extent that its use is increasing markedly. Particular-improvements allow load application up to the strength of the bolt within 2 min, reduction in cost, self-extinguishing features in the resin, improvements in manufacturing techniques, and an improved water- insensitive casing. At the same time, smaller bolt sizes have allowed reduction in resin volumes with consequent cost reduction. At this stage several aspects remain to be improved, particularly specialty anchors for specific purposes and Packaging.

Jan 1, 1971

By R. L. Thayer, D. L. Auer

A review of bentonite production and quality control methods, is presented along with an update on techniques employed by the bentonite industry. This paper also includes an overview of bentonite market demands and long-range supply with resulting emphasis on changes in bentonite testing methods required to utilize existing reserves.

Jan 10, 1979

By R. L. Thayer, D. L. Auer

A review of bentonite production and quality control methods, is presented along with an update on techniques employed by the bentonite industry. This paper also includes an overview of bentonite market demands and long-range supply with resulting emphasis on changes in bentonite testing methods required to utilize existing reserves.

Jan 1, 1980

By Hugh Henton

THIS paper is the result of an investigation made in association with Dr. Charles H. Fulton. Early in 1918 a search was started for methods of utilizing, in the manufacture of basic refractories, certain domestic resources in magnesites, dolomites, and magnesian limestones. Much information was collected during that year and during 1919 regarding magnesite and dolomite deposits. During 1920 and 1921 a research was made into methods of calcining dolomite and separating magnesia therefrom. Some success was attained and many new ideas were brought out in connection with the preparation and utilization of magnesia in the form of "caustic" or light-burned material as well as in the form of refractory or "dead-burned" material. Stimulated by this success, much advance has been made in manufacturing processes for the "plastic magnesia," so called, used for magnesia cement, stucco, flooring and otherwise in the structural industries.

Jan 3, 1926

By C. A. Rowland, R. C. Nealey

Until recently there were very few dry grinding rod mills used. The early installations performed as anticipated. In the last seven years a number of dry grinding rod mills have been made, most of which have been used for grinding iron ore. The recent installations have not operated as anticipated in accordance with practices learned from wet rod milling. The paper does not establish any definite rules for the application of dry grinding rod mills but does attempt to establish some guidelines that can be followed. The paper reviews a number of flowsheets describing the problems encountered and some of the solutions found. Completely dried compared to partially dried feed is reviewed. Problems encountered in scaling up from pilot plant to production-size mills are described. Rod sizing, effect of rod length, rod bending, rod breakage, and rod tangling are discussed. While wet grinding rod mills have been used for 50 years to grind ores and make specifications sands, dry grinding rod mills have only recently come into significant use in the mineral industries. Among the materials now being processed in dry grinding rod mills are (1) lead sinter, lead slag, and limestone; (2) iron ore; (3) silica; (4) cement clinker; and (5) coke. Because the application of wet grinding rod mills was well understood at the time that dry grinding rod mills were introduced, the criteria and guidelines for selecting the former were carried over to the selection of the latter - in some cases with the anticipated results, but in many cases not. It is the purpose of this paper to describe, through a series of flowsheets, some of the recent problems encountered with dry grinding rod mills, to point out the solutions to these problems, and to set forth some guidelines for the selection and application of these mills. When dry grinding rod mills came into use, the following facts about their wet grinding counterparts were already well established: (1) The performance of large-sized mills can be accurately predicted from the performance of rod mills 5 or 6 ft in diameter. Wet grinding mills as large as 14 ft in diameter (inside shell) by 20 ft long with rods 19.5 ft long can operate satisfactorily.

Jan 1, 1970