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By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By M. E. Poad

In 1986, a cooperative effort by the Homestake Mining company, the U.S. Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will be safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modelling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1994

By Leslie S. Halasz

This paper describes the techniques implemented at Randfontein Estates to develop twin-haulages at 'high speed'. An operation which culminated in the world record advance for twin-end multiblast cyclic development in hard abrasive quartzites. A major expansion project was planned for the mine, with the sinking of a third twin-shaft system (to be known as Cooke No. 3), to raise the level of ore production from 3 500 000 to 5 000 000 tonnes per alumm. Subsequent redesign of the proposed shaft system as a single 9 m brattice wall shaft took place, reducing the planned shaft sinking period by 12 months and saving an estimated R 250 000 (U.S. $ 330 000) in sinking costs. The advancement of the Cooke No. 3 Shaft sinking and development programme necessitated a rapid excavation schedule for two interconnecting twin-haulages from the existing Cooke No. 2 twin shaft complex to provide a second means of egress. An early holing between the two shafts would provide significant financial and technical benefits. Pre-development and equipping of shaft pillar excavations would enable a rapid shaft production build up and blocking out of at least one year's ore-reserves.

Jan 1, 1983

By D. R. Spears, D. A. Stanley

The US Bureau of Mines investigated the fundamental aspects of shear-flocculation using a rapid, in-situ particle size analyzer. Silica was stirred in the presence of an aliphatic amine to determine the effects of collector coverage, stirring speed and solids concentration on the kinetics of shear-flocculation. The results showed that shear flocculation is a two-stage process. In the first stage, which occurs during the first 1-2 min. of the reaction, the mean particle size increases rapidly, and in the second stage, an equilibrium is set up between the rates of floc growth and floc decay. Collector dosage affected the position of the equilibrium by altering the number of surface sites for particle-particle attachment. A minimum stirring speed was necessary for shear flocculation, which was dependent on solids concentration and collector dosage. This stirring speed was the minimum necessary for particles to overcome the electrostatic energy barrier, and that results in keeping the conditioned particles dispersed. Larger particles flocculated more rapidly. At very high stirring speeds, large flocs became unstable, resulting in a narrowed particle size distribution in the slurry.

Jan 1, 1995

By R. Hogg, P. Bunnaul

Sedimentation in highly, flocculated suspensions of fine particles, such as clays, occurs through individual settling units (flocs) that have very open structures and correspondingly low densities (typically less than 5% solids by volume). Such settling processes rapidly lead to the buildup of a bed of flocs that are essentially close-packed, with an inter-floc porosity of perhaps 50%. However, the overall solids content is no more than about 2% to 3% by volume. Consequently, the thickening process is dominated by the bed consolidation rather than by the simple settling of the individual flocs. Experimental measurements of sediment consolidation in flocculated clay suspensions indicate, for a given system, that consolidation rates are essentially determined by the solids concentration and can be evaluated using the classical Kynch treatment. However, these rates are strongly dependent on the physical, as well as the chemical, conditions of the flocculation process. Furthermore, the extent to which gravity consolidation proceeds depends on the total weight of the sediment (i.e., on the bed height and the solids concentration). The implications with respect to thickener operation and the requirements for the laboratory testing for thickener design are discussed.

Jan 1, 1993

By Z. M. Zavodni, M. K. McCarter

This paper identifies physical conditions responsible for past instability of the Main Hill area in Kennecott Copper Corporation's Bingham Canyon Mine, Bingham Canyon, Utah, and describes successful stabilization techniques employed in this slide zone. Geotechnical highlights of recent slides are presented, including monitoring, geological engineering data collection, hydrology, physical rock properties, and stability analyses. Local conditions responsible for slope movement in the Main Hill zone are: (1) high pore water pressure that causes a substantial decrease in real and effective material strengths; (2) continuous structural systems that allow sliding in the more competent rock zones; and (3) broad areas containing fractured, altered , and incompetent rock and soil- like materials. The failure mode is structurally controlled and involves a circular-type soil failure in the toe region initiated by excessive pore water pressure. A surface mapping method is presented which assigns rock mass quality on the basis of block size and rock substance strength. This site characterization technique has successfully predicted slide boundaries and failure modes; used in conjunction with laboratory determined shear strengths, it has provided basic input for calculating slope safety factors in the Main Hill slide zone.

Jan 1, 1977

By A. D. Pernichele

Four types of slope failures in waste dumps are recognized; debris flow, foundation failure, edge slump and blowout. The first three types, although at times causing considerable damage to property and interfering with mine operations, are not usually dangerous to personnel because of their slow rate of movement. The fourth type, the blowout, is considered to be the most dangerous because of its explosive mode of failure and lack of forewarning. The December failure at Verona dump is presented as an example of a blowout. Data from piezometer holes indicate that the blowout was due to perched leach solutions near the face of the dump. The level of water in this zone is very closely related to the rate of leach water application on the dump. A detailed analysis of core samples indicated that the impounded water was due to a zonal accumulation of Jarosite which is associated with a buried dump surface. Drain holes proved successful in controlling perched leach solutions in the critical zone near the face of the dump. Monitoring of the water level in the perched zone is considered essential in preventing blowouts. The use of drain and piezometer holes has allowed an increase in the rate of water application on the dump while preventing additional failure.

Jan 1, 1971

By G. E. S. Valadão

This paper is concerned with studying the dewatering behavior of three samples of iron ore products. The objective is to improve the industrial filtration performance by taking into account the laboratory results. Mineral samples came from the Iron Ore Quadrangle in the state of Minas Gerais, Brazil. These samples represent products from the industrial processing of hematitic ores. The samples have almost the same chemical and mineralogical compositions, but they have different size distributions and different specific surface areas. The filtration tests were performed using a modified Büchner funnel apparatus. The results indicate that size distribution and specific surface area have significant influences on dewatering behavior. For Sample 1, the addition of flocculant and/or surfactant was not essential to improving filtration performance. For Sample 3, the cake porosity and the cake thickness were influenced by the addition of the flocculant. On the other hand, the simultaneous addition of flocculant/surfactant decreased the cake formation time and reduced the cake moisture. For Samples 2 and 3, it was also observed that the industrial operation could be improved by taking into account these laboratory results. Key words: Dewatering, Iron ore, Hematite, Filtration, Flocculation, Surfactant

Jan 1, 2003

By C. R. Daly, D. Biswas

This study presents the development of a simplified artificial neural network (ANN) for the characterization of rock mass with a simultaneous display of its output in a three-dimensional interactive environment as well as in the form of a text document. The system was developed using JAVA object-oriented language, virtual-reality modeling language (VRML) and JavaScript, and it runs on the Internet. The user can walk through a three-dimensional virtual roadway, checking the underground rock mass behavior and, consequently, can design a support system. The system first characterizes the rock mass with the help of a neural network and recommends a suitable support system for the particular geomining condition. The system then represents its output in a three-dimensional environment. The neural network developed in this system was trained with 261 data sets, and its performance was evaluated with five case histories. The evaluation results showed that the network could identify the rock category and support system adaptively. The average error for the support load was 2.7%. Among the five case histories, two were represented in a three-dimensional environment. The output obtained from the overall system compared favorably with the existing underground conditions.

Jan 1, 2003

By Al. Valero

This paper quantifies in universal units (energy units), the annual decrease in the mineral endowment of the planet. This is done for some important extracted non-fuel minerals, namely aluminium, cobalt, chromium, copper, gold, lead, uranium and zinc and is compared with the depletion figures of conventional fossil fuels. The results of this study reveal that each year, the decrease of the global non-fuel mineral bonus provided by Nature is 2 to 3 orders of magnitude greater than the loss associated to the burning of fossil fuels. Particularly for 2008, the depletion in mineral wealth of the studied commodities was about 20 times greater than that of fossil fuels. The assessment methodology is based on the Second Law of Thermodynamics. It quantifies the useful energy (exergy) required to concentrate a mineral from a completely dispersed state in the crust, to the conditions of composition and concentration found in the mines. Exergy can be a useful measure for quantifying the mineral depletion caused by man, as it takes into account the main physical features that make minerals valuable: composition and concentration. This analysis enhances and puts numbers to the importance and necessity of material reuse and recycling.

Jan 1, 2011

By Al. Valero

This paper quantifies in universal units (energy units), the annual decrease in the mineral endowment of the planet. This is done for some important extracted non-fuel minerals, namely aluminium, cobalt, chromium, copper, gold, lead, uranium and zinc and is compared with the depletion figures of conventional fossil fuels. The results of this study reveal that each year, the decrease of the global non-fuel mineral bonus provided by Nature is 2 to 3 orders of magnitude greater than the loss associated to the burning of fossil fuels. Particularly for 2008, the depletion in mineral wealth of the studied commodities was about 20 times greater than that of fossil fuels. The assessment methodology is based on the Second Law of Thermodynamics. It quantifies the useful energy (exergy) required to concentrate a mineral from a completely dispersed state in the crust, to the conditions of composition and concentration found in the mines. Exergy can be a useful measure for quantifying the mineral depletion caused by man, as it takes into account the main physical features that make minerals valuable: composition and concentration. This analysis enhances and puts numbers to the importance and necessity of material reuse and recycling.

Jan 1, 2011

By D. L. Monroe

Technical service is assuming an increasingly important role in the sale of asbestos fibre,, Manufacturers are examining raw materials more closely than ever before in order to, obtain the most efficient usage in their processes. Asbestos is one of the more difficult materials to evaluate and consequently has been are of the last to be subjected to evaluation. The main problem encountered in the evaluation of asbestos fibre is that minor differences in grade and texture are not shown up by chemical analysis, and are identified only by specialized physical analyses or actual production use. However, such minor differences become more critical as manufacturing processes are made more efficient, and many purchasing agents and plant chemists are applying a closer scrutiny to their supply of raw asbestos fibre. Many processes have been formulated around grades and qualities of asbestos fibre, which were standard some time ago, but which may now be subject to modification and improvement.

Jan 1, 1959

By Darrell M. Hladun, Linda M. Dufour

The benefits of computer simulation in the design of a refracto­ry gold autoclave facility is discussed. Three computer simula­tion programs used for autoclave design are briefly described in this paper. 1) METS IM® - A Process Simulation Software Package Developed by Proware: Mass and energy balances are conducted around the auto­clave and its ancillary processes. Results from the process simulation define process equipment requirements and are used for establishing operating costs. The p_rocess model integrates various unit operations including grinding, acidu­lation, pressure oxidation, counter-current-decantation, neutralization, cyanide leaching, and carbon-in-pulp or car­bon-in-leach. 2) ALGOR® - Finite Element Analysis (FEA): A computer software program is used in the design and analysis of brick lined pressure vessels, such as autoclave, heater, and flash vessels. This software creates a steady state thermal model, and accurately predicts temperature distribution throughout the entire vessel, including nozzles, which represent regions of high thermal intensity. 3) Compress©: A software package developed by Codeware used for the sizing of pressure vessel components, includ­ing shells, heads and nozzles, according to ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.

Jan 1, 1996

Iron removal using biologically produced organic acids was investigated as a treatment option for the production of refractory grade bauxite. A leaching solution containing 98mM oxalic and 67mM citric acid was prepared from a sucrose medium using for fermentation the fungus Aspergillus niger. The leaching capacity of the metabolic product was tested on a bauxite sample containing 16-19% iron (as Fe2O3). Aerobic and anaerobic leaching tests were carried out at pH 3, 50°C and in the absence of light. Results indicated that more than 80% of total Fe can be removed from the ore, when the sample is finely ground and applying a two stage treatment. The presence of oxygen was seen to affect adversely the kinetics of the process, suggesting that leaching follows a reductive mechanism. Experiments that were carried out with different particle size fractions indicated that for obtaining efficient removal of iron particles should be finer than 0.63mm. Reduction of the operating temperature from 50 to 30°C caused a decrease in the rate of iron removal by more than 10 times.

Jan 1, 2006

By R. M. Barker

The historic Getchell property is currently being mined from the Getchell Main Underground workings, a foot wall extension of the Getchell open pit deposits along the Getchell fault. Drift-and-fill techniques are used to extract the ore through a ramp access. The adjacent Turquoise Ridge deposit is currently under development via two vertical shafts. Together, the two mines will continue to provide feed to the Getchell's 3,200 tpd mill/autoclave circuit, taking Getchell Gold from its current production rate of 200,000 ounces (Au) per annum, to over 400,000 ounces (Au) per annum by 1999.

Jan 1, 1997

By D. Crouse

A significant wollastonite resource has been discovered and evaluated near Seeley's Bay in southeastern Ontario. The deposit occurs in Grenville Frontenac Terrane granulite facies rock within a calc-silicate skarn in contact with Proterozoic-age gabbro. The steeply-dipping and tightly-folded wollastonite skarn beds are interlayered with diopside and quartz-feldspar skarns in a southwest-plunging synclinorium. More than 9 million tonnes of a drill-proven and inferred resource grading 41 % wollastonite has been identified, as well as an additional 3 million tonnes grading 30%. Mineralogical and process test work with the wollastonite from this deposit has demonstrated the potential to produce a high purity, high aspect ratio wollastonite product.

Jan 1, 1994

By Bryan C. Smith, Duane R. Skidmore

Volumetric mass transfer coefficients and gas holdups were measured in a concentric tube airlift reactor designed for the microbial desulfurization of coal. The slurries were comprised of an acidified basal salts solution containing thirteen different weight percents of coal (74 µm Ohio #1) at three temperatures. An enhancement in the mass transfer coefficient, KLa, with respect to that measured in pure solution was found at weight percents of 5 (volume fraction solids, ES = 0.035) or less, the greatest enhancement being as great as 37% at approximately 2 weight percent (ES = J 0.014). At higher solids fractions, the mass transfer coefficient decreased with further solids additions, decreasing by as much as 91% at 40 weight percent coal (ES = 0.315). KLa increased with temperature at all solids concentrations, the greatest increase being 392% at 72°C vs that measured at 30°C. Gas holdup, EG decreased with all increases in solids loading by as much as 65% and increased by as much as 67% with temperature. KLa and EG were correlated with operating conditions separately, and the separate correlations combined to yield overall correlations for the mass transfer coefficient and for the gas holdup. The correlations are suitable for inclusion in system models devised earlier for microbial coal desulfurization processes, and may be used for design, operation and cost estimation for such systems.

Jan 1, 1989

By Cody Edwards, Ross Webb

5 miles of soft ground tunnel excavation for the SAWS W‑6 project finished months early despite difficult conditions. Success was achieved using TBMs and other equipment built long before most of the crew was even born. The old school means and methods easily adapted to the conditions encountered and were key to the project’s success. Unfortunately, an industry trend is to specify more “advanced” equipment which can sacrifice adaptability or productivity for a perceived reduction in risk. This case history discusses when traditional methods may be the best option.

Dec 1, 2022

By Robert J. Neubauer

I was asked here today to discuss the first long-term freight rate contract ever signed by a U.S. railroad and shipper. That was ICG's contract with the hoosier energy company to haul coal from southern Illinois to an Indiana power plant. I?ll also talk about why you can expect to see more such contracts in the future But first, let me tell you a little bit about the Illinois central gulf railroad and why coal contracts are so important to us. ICG is a principal mid-American freight carrier. We are one of the ten largest railroads in the united states and one of the ten largest coal-hauling railroads. ICG links the industrial great lakes region with the warm weather ports of the gulf coast. Some of the major points on our route map are Chicago; Indianapolis; Omaha; Kansas City; Memphis; St. Louis; and, of course, baton rouge and new Orleans.

Jan 1, 1981

By R. J. Smith

Tar sand deposits in Utah represent more than 25 billion barrels of in-place bitumen, 96% of the known U.S. reserves. The technological development of a hot water processing strategy for the Canadian tar sands and the commercial Production of synthetic crude oil from this natural resource suggest that similar success may be possible for the utilization of Utah tar sands to provide our country with a new domestic source of synthetic crude oil. In this regard an active research program to develop a hot water processing strategy for Utah tar sands has been sustained at the University of Utah for the past five years. The hot water process for Utah tar sands differs significantly from that used for Canadian, tar sands due to the inherent differences in the respective bitumen viscosities and the nature of the bitumen-sand association. These differences have led to the identification of certain design criteria necessary to achieve satisfactory phase disengagement during digestion. (8,9) Subsequent flotation of the digested tar sand is a subject of current attention and is considered in this contribution for the Asphalt Ridge tar sand deposit. Although contact angle measurements of pure Asphalt Ridge bitumen indicate moderate hydrophobicity, air bubble attachment to the bitumen concentrate taken from a 37 liter flotation cell is not possible. This surprising result suggests that the flotation separation is dependent on air bubble entrapment rather than on attachment due to surface hydrophobicity. The occlusion of air bubbles in the bitumen is apparent from visual examination of the concentrate, especially at lower temperatures. It seems that a bitumen bubble agglomerate forms in the impeller region of the flotation cell, the effective density of which is such to allow the agglomerate to float to the surface. A factorial design of the major operating variables in the flotation separation indicated that the quality of separation was significantly dependent on the flotation temperature and to a lesser extent on the degree of agitation. For a flotation temperature of 77C recovery of 96.7 percent was realized at a grade of 61.0 percent bitumen. The improved separation at higher flotation temperatures was found to be due to the decrease in bitumen viscosity resulting in more effective rejection of coarse sand from the concentrate.

Jan 1, 1980