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By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology, was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles.

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology, was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

Papers presented at two joint meetings of the Mineral Industry Education Division, Geophysics Committee, the American Geophysical Union and the Committee on College Curricula of the American Association of Petroleum Geologists, at the A I M E meeting in New York on Feb 17 and 18, 1941 At the first meeting, the Musing Geology Committee, the Society of Economic Geologists and the Committee on Applications of Geology of the American Association of Petroleum Geologists also took part [ ]

Jan 1, 1941

By S. A. Jacob

Magnesium sheet is notoriously difficult to form at low temperatures without initiating failure, In the present work cold rolling and annealing conditions are varied to produce samples of AZ3lB sheet with a range of grain sizes. The formability of these samples is investigated using tensile testing and forming limit diagrams (FLD's), The results are discussed in terms of twin types and frequencies.

Jan 1, 2005

By Vishal Shukla, Ashok Kumar, Manas Ranjan, D. Chakraborty, Narayan Sharma

Jigging has a very important role in mineral processing Industry. Upgrading of Iron Ore by jigging has been an emerging trend. A detailed investigation is carried out to understand the influence of Jig feed granulometry and bed height during jigging operation. Noamundi jig plant data shows that variation in jig feed granulometry, feed quality and bed height are major contributors to fluctuation in jigging performance. At Noamundi the feed size (-10.0+0.5mm) fraction is used for fines jigging operation. To understand the effect of granulometrey on jig plant performance such as yield, separation efficiency and Fe recovery. In this context The performance of jigging was evaluated by daily average data from jig operation was used to study the influence of feed distribution on jigging performance .Coarser fraction (+6mm) has a positive influence , whereas fines fraction (-0.5mm) tends to lower performance . During Jigging rearrangements of Particles takes place due to an alternate expansion and compaction of Jig Bed .These particles are arranged by increasing density from top to bottom. During the particle stratification, Jig bed physically cut at desired horizontal particle density plant to separate the desired product. Investigation shows that optimum bed height is required at different Jig feed quality to achieve desired product quality, maximum separation efficiency and Fe recovery. This Paper will illustrate role of granulometry and Bed height control on Jigging plant performance.

Jan 1, 2014

By lchiro Aoi, Hideo Nakae, Makoto Yoshida, Makoto Ishino

"The influence 6f gravity on the microstructure of unidirectionally solidified Cu-Pb monotectic, Ag-Si and Fe-C eutectic alloys is studied. In order to examine the influence of gravity in a lg environment, both the upward (opposite to direction of gravity) and downward (direction of gravity) unidirectional solidifications are carried out. The results are as follows: (1) For the upward solidified Ag-Si eutectic alloy, the eutectic Si continuously grows. On the other hand, in the downward solidified Ag-Si alloy, the Si grows discontinuously and disperses into the ex-Ag matrix. (2) No morphological difference in the eutectic growth is observed between the upward and downward solidified Fe-C eutectic alloys. (3) In the case of the upward solidified Cu-Pb monotectic alloy, a banded structure, which consists of Pb-rich layers and Cu-rich layers, is observed. However, such a banded structure -is not observed in the downward specimen. (4) The banded structure is not found in the upward solidified Cu-Pb-0.05 mass % Al and Cu-Pb-0.1 mass % Al alloys. In the Cu-Pb-0.05 mass% Al alloy, a fibrous -L 2 phase grows continuously parallel to the growth direction at low growth rate. Only 500 mass ppm addition of aluminum induces the morphological change of the monotectic L2 phase.IntroductionThe influence of gravity on the solidification of eutectic and monotectic alloys has been investigated in microgravity environments [l-9]. The purpose of these studies was to obtain a homogeneous microstructure of eutectic or monotectic alloys, most of which alloys tend to solidify with macro-segregation under gravity. However, in most of the previous experiments, e.g., in free fall systems, in aircraft or in space laboratories, the growth rate was too high to realize a planar solid/liquid interface. This would be due to the limited time for solidification. Thus, it was difficult to examine the influence of gravity on the planar coupled growth of the eutectic or monotectic alloy. In this study, both the downward U.D.S. (unidirectional solidification by gravity) and upward U.D.S. (opposite direction to gravity) are carried out in order to examine the influence of gravity on the coupled growth in a lg environment [l0, 11]. In the case of the downward U.D.S. using the current Bridgman method, the molten alloy must be confined between the crucible and the solid."

Jan 1, 2000

Influence of Grinding Media on the Flotation of Carbonate Using Sodium Oleate as Collector

Sep 13, 2010

By R. J. Durrheim, B. Manzunzu, V. Midzi

Selecting ground motion prediction models (GMPM) is crucial in assessing seismic hazard levels in a specific region. This study investigates the influence of ground motion model (GMM) selection on seismic hazard assessment in Johannesburg, South Africa. Most seismic events affecting Johannesburg are related to mining activities and water ingress into the underground mine voids. The most seismically active regions in South Africa include areas around Klerksdorp, Welkom, and Carletonville. These regions experience a significant number of earthquakes, with mining activities being a major factor contributing to seismic events. Ten ground motion prediction equations were selected from regions of similar tectonics setting and were assessed to see if they correspond to the available local data. Six of these were also compared to the ground motions produced by the earthquake of 14 August 2014, which occurred in the Orkney area, one of the mining areas in South Africa. Sensitivity analyses were also carried out to assess the influence of ground motion prediction equations (GMPE) on the seismic hazard of Johannesburg. The results indicate that the choice of GMPM significantly affects the estimation of seismic hazard levels in Johannesburg. Different GMM can lead to varying ground shaking intensity predictions, impacting risk assessments and engineering design considerations. The findings highlight the importance of carefully selecting appropriate GMM tailored to Johannesburg’s specific geological and tectonic characteristics. Understanding how different models perform in this region is essential for accurate seismic risk mitigation strategies.

Jan 12, 2025

By S. F. Kaplan, A. S. Dolotov, V. N. Kovalev

"The proportion of refractory sulphide ores and concentrates in world gold mining industry is growing every year. Pressure oxidation of these materials (in autoclave) allows to oxidize gold hosting minerals. Traces of halides and pseudohalides present in the slurry liquids contribute to formation of complex gold compounds. Sorption-active carbon present in ores leads to irreversible adsorption of complex gold compounds and their loss. The objective of the research is to study gold extraction dependence on the concentration of chloride-, cyanide- and thiocyanate-ions in the slurry liquids during pressure oxidation. Double refractory flotation concentrate of the Bakyrchik deposit was used for the testwork. The research was planned on the basis of a full factorial experimental design with additional refining experiments. Ligand concentrations (0 – 1000 mg/l Cl-, 0 – 600 mg/l CN-, 0 – 1200 mg/l of SCN-), temperature (200 – 240 °?) and retention time (1 – 6 h) were used as variables of pressure oxidation process. It was determined that sulfide minerals oxidize much faster than ""organic"" carbon. Under the conditions of T = 240 ?C, t = 2 h, sulphide sulfur oxidation was 95.6%, while ""organic"" carbon oxidation was 46.1 %. Each of the examined ligands has a significant adverse impact on gold extraction. Analysis of the experimental data demonstrated that with a high degree of confidence (R2 = 0.883) gold extraction does not depend on the ligand type, but only on its concentration and the ""organic"" carbon oxidation degree. In case of complete oxidation of ""organic"" carbon, the presence of the ligand (L = Cl-, CNS-, CN-) in the liquids at a concentration of up to 20 millimole/L does not significantly affect gold extraction. The assumption that the main factor of preg-robbing in ???-CIL treatment of double refractory concentrates is the natural ""organic"" carbon sorption-active to gold has been confirmed. INTRODUCTION In recent decades, placer gold mining has been gradually declining and hardrock gold mining, including ""refractory"" gold mining, has been growing all over the world, as well as in the Russian Federation (http://www.miningworld.ru, 2015). One of the main reasons why gold ores are refractory is gold adsorption on natural carbonaceous materials (""organic carbon""). Only a few technologies are suitable for processing such ore concentrates (a significant amount of gold is contained in refractory hardrock ore both in Russia and worldwide) (Vorob'yev-Desyatovskiy N.V., Yepifanov A.V., 2014)."

Jan 1, 2018

By P. J. Uggowitzer, H. Kaufmann

"New Rheocasting is a novel route of semi-solid casting, in which the globular semi-solid precursor material is produced by controlled cooling of only slightly superheated melts in conventional steel crucibles. The resulting semi-solid slugs are placed into the sleeve of a vertical Squeeze Casting Machine and then filled into steel dies. Solidification occurs under hydraulic pressures up to 100 MPa Due to the reduced cost of precursor material, reduced investment cost and easier recycling, the New Rheocasting process offers cost reductions of up to 25% over conventional semi-solid casting · routes. The New Rheocast products are pore free, pressure tight, weldable and heat treatable castings.In the present work the New Rheocasting Process is introduced and the influence of heat treatment on mechanical properties of the New Rheocast alloy A356 is discussed.The alloy A356 is cast under ideal New Rheocasting conditions into a step die on an UBE HVSC 350 Squeeze Casting machine. As-east, TS and T6 heat treatment conditions with variations in solutionizing and aging time/temperature parameters are applied and the samples are tested by tensile testing. Alternatively, the same heat treatment conditions are applied to conventional Squeeze Casting parts and compared with New Rheocasting.Questions of potential cost savings due to modified heat treatment conditions are also addressed in this paper."

Jan 1, 2000

By C. F. Smart

THE heat treatment of the bronze composed of 88 per cent. copper, 10 per cent. tin, and 2 per cent. zinc, has been investigated by H. S. and J. G. S. Primrose,1 and also by the U. S. Bureau of Standards.2 The results obtained by H. S. and J. G. S. Primrose on dry-sand castings subjected to reheating followed by air cooling, or by quenching in water, are shown in Figs. 1 and 2. The values for tensile strength have been FIG. 1.-EFFECT OF QUENCHING ON DRY SAND CASTINGS (H. S. AND J. G. S. PRIMROSE.) converted from tons per square inch to pounds per square inch. Figs. 3and 4, have been plotted from values obtained by the Bureau of Standards on material of the same composition and treatment. Both investigations show that the ductility of the cast bronze is improved by heating to 700° C. and cooling in air, the strength not being impaired by this treatment. They are not in agreement, however, as to the effect of quenching, Messrs. Primrose reporting a decrease, and the Bureau of Standards an increase, in both strength and ductility when the cast bronze is heated to 600° or 700° C. and quenched.

Jan 9, 1919

R. F. WOOD,* Sandusky, Ohio.-I made a few tests of gun-metal specimens, after I noticed the results on quenching -reported by the Bureau of Standards. The data of one such test are given herewith. The bars were heat treated and quenched before they were machined, and in all cases they were brought up to 700° or 800°. They became extremely brittle,, showed almost no elongation, except such as was caused by the failure of the pieces to fit together after they were pulled, and the tensile stength was reduced from around 35,000 to about 13,000 lb. per sq. in. In addition, the weakening effect of the quenching seemed to be almost as marked when the bar was allowed to slowly air-cool from red to black, and then quenched, as it was by quenching directly from the red heat. Test Bars.-Rough size, 9/16 in. diam. over test section, grips 13/16 in. diam. Cast two in a flask, one on each side of a block 8 by 4 by 1 in. and fin-gated thereto from the grips but not from the test section. Poured with flask in inclined position, with gate to lower end of block and riser from upper end of each test bar. Bars were machined to ½ in. over the test section, after heat treatment. Casting the Bars.-Charge of 1500 lb. consisting of 400 lb. of new metals and 1100 lb. of G turnings and scrap was melted in open-flame oil furnaces and then poured into a 1-ton ladle. From the ladle 150 lb. was poured into a preheated No. 50 crucible, land from this the flasks of test bars were poured. The six flasks are indicated below by the numbers 1 to 6 and the bars in each flask by the letters a and b, thus 4a and 4h, for instance, were the two bars in flask No. 4.

Jan 12, 1919

GEO. F. COMSTOCK,* Niagara Falls, N. Y. (written discussion?).-This interesting paper throws additional light on a question about which differences of opinion have apparently existed in the past, and the writer would like to record in this connection the agreement of his experience with that of Primrose and Prof. Smart in regard to the effect of quenching on the properties of gun-metal bronze. The writer's results have been published, so that there is no need for a detailed report, here, but his in-vestigations resulted in showing that both gun metal and manganese bronze are ruined by quenching in water from a red heat, apparently because they cannot stand the strains produced by the sudden cooling. The lines, mentioned by Prof. Smart, in a polished and etched section of the quenched metal have also been noticed by the writer, who however has not found them any different in quenched specimens than in annealed specimens. Since they appear only after etching, it would seem most probable that they are merely grain boundaries in most cases, though Prof. Smart's idea that they are indications of strains is by no means impossible. Fig. 1 shows how these lines appeared on the author's speci-mens of annealed gun metal, etched with ammonia and hydrogen per-oxide, and magnified 100 diameters.

Jan 11, 1919

By Henrique Lacerda Eleutério, Aldo Henrique de Almeida Barbosa, Vicente Tadeu Lopes Buono

The automotive industry’s interest in galvannealed (GA) boron steel for hot forming processes application has been steadily increasing due to its excellent surface quality, galvanic protection provided to the parts, good paint adhesion and better weldability in relation to other coatings for this application. In this study, samples of 22MnB5 galvannealed steel were heat treated and hot stamped on a water cooled die in laboratory scale. The influence of heat treatment on stability of coating and steel was assessed by using initial heating rates 11.0ºC/s and 15.0ºC/s. Microstructural evolution of galvannealed coating and structural integrity of steel during hot forming were investigated by scanning electron microscopy with energy dispersive spectroscopy analysis (SEM/EDS/Line scan), X-ray diffraction (XRD) and optical microscopy (OM). It was possible to quantify the Fe-Zn phase evolution during hot forming, to understand the effect of these heating rates on the product properties and to establish an optimized heat treatment for hot forming of these steel. The heat treatment with the heating rate of 15.0ºC/s presented greater operational flexibility and final products free from surface defects or cracks in the substrate.

Oct 1, 2019

By Jeff R. Reinson

The Diavik Diamond Mine is producing diamonds from two orebodies, the A154 South and A154 North kimberlite pipes, discovered beneath the waters of Lac de Gras. Innovative dike technology with appropriate water collection and treatment systems allowed Diavik to start open pit mining of the ore bodies in 2002. To allow planning, engineering, and implementation of sufficient water handling infrastructure, reasonably accurate estimates of groundwater inflow quality and quantity over the life of mine are required. Prior to mining, a numerical model using the continuum approach was developed for regional and site wide water management. After approximately two years of mining, groundwater inflows to the pit were found to exceed those predicted by the base case hydrogeologic model. The most likely explanation was flow through Dewey?s Fault zone. As this fault was not explicitly accounted for in the model, a detailed hydrogeologic investigation was conducted to evaluate its geometry and hydraulic properties. A multi-disciplined approach was used and involved core logging, fluid logging, geophysical logging, packer testing, a pumping test, and water quality sample collection. The results of the field investigation were used to update the conceptual and numerical models and to develop a Discrete Fracture Network (DFN) model to address small scale problems such as flow into future underground drifts. The updated numerical hydrogeologic models predict that up to 70 per cent of the groundwater inflow to the A154 N/S open pit is through the relatively narrow fractured rock zone associated with Dewey?s Fault. Consistent with the continuum model, the DFN model predicts that inflow to a drift excavated in Dewey?s Fault will be approximately 10 times the inflow to a drift excavated in competent rock. The DFN model provides a better understanding of the distribution of these inflows on a local scale over the length of the drift.

May 1, 2006

By M. J. Raffaldi, K. W. Harris, K. A. Perry

"Highwall miners have been widely used to extract additional coal reserves from existing surface operations, particularly on contour operations in the Appalachian coalfields. Using a continuous miner cutting head, coal may be extracted from significant depths (such as 150 m), leaving behind an array of web and barrier pillars with the purpose of maintaining highwall stability. This method inherently involves elevated risks to both equipment and personnel due to proximity to and increased exposure time near highwalls. As a result, modern operations should actively design web and barrier pillars to maximize extraction while providing adequate stability. The ARMPS-HWM software, an empirical-based program created for the design of web and barrier pillars at highwall mining operations, is one such approach. The calculated stability factor is compared with empirically established guidelines produced from examining case histories.The ARMPS-HWM program is a handy tool for initial design, but understanding the site’s structurally significant geologic features and geomechanical behavior is important and may potentially increase extraction. We created a two-dimensional numerical model using FLAC3D and calibrated it to ensure pillar strength, closely following the Mark- Bieniawski formula for a typical range of pillar geometries and overburden properties. The development of pillar stresses along a highwall panel was then numerically investigated as mining progressed, and the stress distribution between barrier pillars was found to be asymmetric, which can result in an over-design of the closeout web pillars if tributary area loading is assumed. Finally, the importance of adequate barrier pillar stability is highlighted."

Jan 1, 2014

By W. Pawlos, A. Bakalarz, M. Duchnowska

This paper presents the results of an investigation into the influence of hydrodynamics on a preflotation process for the copper sulfide ore from the Fore-Sudetic Monocline deposits in Poland in a flotation machine. The main aim of the preflotation stage for Polish copper ore is to remove the easy-to-float organic matter — organic carbon — that causes serious problems in metallurgical processes. The organic matter is connected with the presence of shale ore. This paper describes the preflotation experiments conducted to investigate the effect of various stirrer speeds. The upgrading selectivity of copper and organic carbon were analyzed and compared. The results show that the effectiveness of separation between organic carbon and copper decreases with increased stirrer speed in the laboratory flotation machine. The more intensive the mixing of the flotation suspension, the lower the selectivity of the preflotation experiment. Lower stirrer speed probably provides lower mechanical entrainment and flotation of copper minerals.