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By W. G. Pariseau

Regression analysis of calculated on measured displacements were used to assess the influence of fill and fold plunge on shaft pillar mining at the Homestake Mine. These effects were neglected in the original three-dimensional finite element analysis undertaken in 1991. An average fold plunge of 15? and a 24K fill (Young’ modulus of 24,000 psi or 165 Mpa) were used in the reanalysis. Measured displacements were obtained from an array of 36 m (120 ft) multiple-position borehole extensometers installed in June 1994 and read to March 2003. Results indicate the effects of both on calculated displacements and thus on regression parameters are noticeable. However, these neglected effects would not have changed the original inference of Ross Shaft stability during pillar mining.

Jan 1, 2004

By A. M. Tunstall

Blasting is commonly viewed separately from mechanical handling and crushing. This view is misleading because the degree of fragmentation achieved by blasting can have a significant effect on the efficiency of these processes and, hence, on the overall cost of the mining operation. In this paper, aspects of blasting and crushing and their interaction are examined. A case study is also presented that dramatically illustrates the influence of blast fragmentation on subsequent processing and on the financial implications involved.

Jan 1, 1998

By A. M. Tunstall

Blasting is commonly viewed separately from mechanical handling and crushing. This view is misleading because the degree of fragmentation achieved by blasting can have a significant effect on the efficiency of these processes and, hence, on the overall cost of the mining operation. In this paper, aspects of blasting and crushing and their interaction are examined. A case study is also presented that dramatically illustrates the influence of blast fragmentation on subsequent processing and on the financial implications involved

Jan 1, 1997

By R. D. Hansen, R. R. Klimpel

This paper discusses the influence of frother type and dosage on recovery/selectivity in coal/sulfide mineral flotation as a function of particle size. It is shown that different frother structures exhibit quite different but consistent performance characteristics depending on the underlying particle size ranges involved as well as the dosage levels of both the frother and collector. The data presented on existing commercial frothers and some new special purpose experimental frothers is used to illustrate some general operator guidelines on proper frother selection and use.

Jan 1, 1987

By Robert S. Neil, O&apos

The basic transportation planning process consists of: 1. Inventories and analyses of existing conditions. 2. Estimates of future growth. 3. Determination of future travel demand. 4. Testing alternative systems to satisfy future travel demand. The many modeling techniques used in the transportation planning process are well known, commonly accepted, and thoroughly described in readily available literature. This paper will concentrate on the fourth step of the planning process, specifically the development of alternative systems for testing, and will discuss some of the factors which should be considered during the development of alternative systems. There are many factors which require consideration and which have a bearing on the configuration of alternative test systems. These comments will be limited to the influence of geographic, demographic, geologic, and economic factors. Although addressed separately, the four are to a great extent related and have a significant effect on each other. The objective of examining these factors during the early phases of system planning is to assure that more detailed corridor studies will not be stymied by considerations which could have been anticipated and accommodated at an earlier time. It is particularly important that feasibility of construction be assured before test systems lead to corridor decisions and accompanying commitments to

Jan 1, 1974

By Kenneth L. Schellie

In preplanning the reclamation of a pit or quarry the geology of the site is the name of the game! The planner must know the parameters of the deposit, the quantity and kind of earth materials to be removed, and the amount and nature of the materials to be left behind or wasted as the result of processing the marketable product. With many states and most local jurisdictions requiring reclamation plans prior to the issuance of mining permits, the need for accurate and complete data concerning the geology of the site becomes increasingly important. The producer need only know that marketable materials are available in sufficient quantity to make the mining operation economically feasible-the planner, in order that the land may be reshaped for a useful purpose, must have reasonably precise information as to the dimensions and configurations of the pit or quarry following extraction and the amount and type of materials available on the site (or in some cases offsite as well). Therefore the geology of the site is of major significance in determining the land forms and use capabilities of the property upon completion of the mining process.

Jan 1, 1974

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.

By David B. McWhorter, John D. Nelson

INTRODUCTION The quantity of seepage that will be released from a tailings impoundment depends not only on the characteristics of the seepage control system, but also on the properties of the foundation soil or rock beneath the impoundment and the nature of the groundwater in the area. The interaction between various elements of the seepage control system and the influence the various characteristics of the site and impoundment have on seepage are the subject of this paper. The results of analyses are presented herein to indicate the nature and magnitude of the effect that the various factors will have on seep¬age losses. Analyses were conducted for a uranium mill tailings impoundment located in an area characteristic of many found in the western United States or Canada. A typical seepage control system consists of placement of either a clay or synthetic liner beneath the impoundment. In some cases an underdrain system may be placed on top of the liner to collect drainage from the tailings. The parameters that were varied in the analyses included those pertaining to the liner, underdrains and foundation strata. In general, it is shown that the seepage losses will vary in a complex manner depending on the interaction of the elements of the site and the seepage control system. As may be expected, the liner and underdrain systems have the most pronounced effect on controlling seepage. This paper deals with the quantity of seepage released from an impoundment However, the impact that seepage losses from an impoundment will have on the surrounding environment will depend on the rate at which contaminants will enter the groundwater and the nature of the groundwater flow itself. Consequently, when considering these results with regard to environmental impact they must be interpreted along with considerations of geochemical factors. MECHANICS OF SEEPAGE The mechanics of seepage and methods of analysis that were used will be discussed briefly herein. For a more detailed discussion the reader is referred elsewhere (McWhorter and Nelson, 1978, 1979, 1980). A general column through the impoundment was considered to be as shown in Fig. 1.

Jan 1, 1980

By Dennis K. Mortensen

Improvements in metallurgical performance are continually being made in the attempt to achieve the metallurgist's goal of maximum concentration, minimal loss of recovery and at costs that maximize profit margins. Innovative technological advances provide a means for the metallurgist to more thoroughly understand the mechanisms of separation and foster new ideas from old. Problems associated with the implementation of new technology can be overcome effectively if the metallurgist thoroughly understands the metallurgical systems with which he is working.

Jan 1, 1991

By M. SIDDARAJU, Rameshwar Sah, T. Umadevi, K. S. SRIDHARA, M. RAJU, GANESH SHETTY

With the depletion of high-grade iron ore resources, the utilization of existing low-grade iron ores, fines and tailings with effective beneficiation is inevitable to meet the iron and steel industry’s required specifications and demand. JSW Steel Limited is operating a 17-mtpa beneficiation plant at its Vijayanagar site in Bellary in Karnataka, which produces nearly 50 to 54 percent concentrate as sinter-grade fines. The sinter base mix consists of iron ore fines that are smaller than 10 mm, with 41 percent smaller than 0.150 mm; washed ore that is generally smaller than 3 mm and bigger than 0.150 mm, with 3 to 9 percent smaller than 0.150 mm; beneficiation plant concentrate, with 97 percent smaller than 0.150 mm; limestone; dolomite; coke breeze; lime; sinter return fines; direct reduced iron (DRI) fines; and micropellets produced from steel plant waste. Using more washed ore in the sinter base mix affects the sinter quality. Ball formation in the mixing and nodulizing drum is an important step in sinter making and requires sufficient quantity of smaller than 0.150 mm fines. Optimization of fines in the sinter base was carried out by replacing the smaller than 10 mm iron ore fines with washed ore. Size analysis, study of the granulation index (G index) and optimization of moisture with respect to sinter bed permeability were carried out to optimize the proportion of smaller than 0.150 mm fines in the sinter base mix as adhering material. This study explores the optimization of fines in the sinter base mix for ball formation to achieve higher sinter quality and productivity with higher sinter bed permeability.

By M. SIDDARAJU, Rameshwar Sah, T. Umadevi, K. S. SRIDHARA, B. D. Ganesh Shetty, M. RAJU

The production of high strength iron ore sinter for blast furnace iron making unit was developed by optimizing the granulometry of less than − 0.150 mm fines in sinter base mix which consists of iron ore fines (− 10 mm size with 0.150 mm: 41%), beneficiation plant jig concentrate, i.e., washed ore (− 3 + 0.150 mm size with − 0.150 mm 3 to 9%), beneficiation plant concentrate (− 0.150 mm size 97%), limestone, dolomite, coke breeze, lime, sinter return fines, direct reduced iron (DRI plant) fines, and micropellets produced from steel plant waste. The sintering process consists of preparation of base mix, mixing, and production of nodules using mixing and nodulizing drum by maintaining the optimum moisture, transferring of nodules to the sintering machine, and firing of sinter by applying optimum suction pressure. To optimize the < 0.150 mm fines in sinter base mix, the − 10-mm size iron ore fines was replaced with washed ore. The size analysis, granulation index (G index), and optimization of moisture w.r.t. sinter bed permeability were carried out by varying the washed ore addition from 0 to 55% in sinter base mix to vary the − 0.150 mm fine size. With decrease in washed ore addition from 55 to 0% in sinter base mix the finer fraction, i.e., − 0.150 mm in sinter base mix increased from 9.4 to 26.7%. Granulation (G) index increased from 1.46 to 3.10, sinter bed permeability increased from 33 to 53 Japanese Permeability Unit (JPU), and balling index increased from 1.4 to 3.0. With increase in − 0.150 mm fines in the sinter base mix from 9.4 to 26.7%, the sinter tumbler index (T.I) increased and sinter reduction degradation index (RDI) decreased. Increase in sinter strength and decrease in sinter RDI was due to increase in formation of Silico ferrite of calcium and aluminium (SFCA) phase and decrease in pore phase. The SFCA is the main bonding phase in iron ore sinter, and it provides strength to sinter. Sinter base mix with − 0.150 mm fines 18.9% (washed ore addition 25%) achieved desired sinter properties with moisture 8.0%, G index 2.44, balling index 2.3, and sinter bed permeability > 45JPU. Decreased the sinter properties with washed ore addition in sinter base mix beyond 25% due to decrease in − 0.150 mm fines in sinter base mix. Further, to improve the sinter properties with washed ore 30 to 45%, 3 to 10% beneficiation plant concentrate, i.e., − 0.150 mm fines was added to maintain the 18.9% of − 0.150 mm fines in sinter base mix. From the laboratory sintering studies, it was found that minimum 18.9% (range from 18.9 to 26.7%) − 0.150 mm fines should be maintained in the sinter base mix to achieve desired sinter properties.

Oct 16, 2021

By Vivek Priyadarshi, VIVEK KUMAR HIMANSHU, A. K. Vishwakarma, M. P. Roy, A. K. Mishra, RAVI SHANKAR

The nature and orientation of joints in rock strata affect the damage pattern under explosive loading. Most of the limestone deposits in India are found with severity of joints. Categorically, these joints may have variable orientations such as dipping out of the blast face, inside the face, horizontally or having strike parallel to the face. The damage pattern under the varying category of orientation will be different. Accordingly, a numerical model in Ansys-Explicit Dynamics was prepared to compare the damages of rock mass under different joint orientations. The physical nature of a joint reflects frictional and stiffness behaviour. Accordingly, the damages have been compared under bonded and frictional nature of joints. The output damage pattern from the model has been validated on the basis of blastability index proposed by Lilly. Different limestone mines in India show different nature of jointing in their rock strata. Accordingly, the blasting outputs from three different limestone mines, viz. Rawan limestone mine, Sagmania and Birhauli limestone mine and Injepalli limestone mine, have been compared along with their blast design parameters and the nature of joint. The comparative results show that the closely spaced horizontal joints support maximum in burden movement and rock fragmentation due to blast.

Nov 23, 2023

By Giuseppe Gaspari, Xiangrong Wang

The pandemic emergency is forcing transit agencies to define strategies allowing social distancing, which are more challenging in underground interchange stations in crowded downtown cores. Toronto Transit Commission’s (TTC’s) Bloor-Yonge Station Capacity Improvement Project in Toronto was approved to meet increasing demand and represents an opportunity to fight COVID-19. This paper discusses cost-effective solutions in expanding the cut-and-cover station box over the existing Toronto Subway Line 2 and connecting it through ventilation openings in the cast-iron tunnel liner. Potential uplift risks and structural damage due to minimal vertical clearance were analyzed via three-dimensional finite element analyses with advanced constitutive laws to simulate the multi-stage construction process. Based on the simulation results, a series of countermeasures, including excavation support systems, king posts, ground-consolidations, and liner reinforcements were integrated into comprehensive design options to ensure the serviceability and structural integrity of the subway tunnels.

Jun 13, 2021

By J. Y. Kim, S. L. Chryssoulis

Lead ions that originate from galena during the processing of complex sulfide ores migrate onto the surfaces of sphalerite and iron sulfide minerals. This results in poor selectivity during differential flotation. Generally, in sulfide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. The surface lead complicates the zinc flotation circuit by lowering the concentrate grade. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zu and Pb-Zu ores is discussed. Plant and laboratory-test data are interpreted by determining the surface compositions of individual grains of sphalerite and iron sulfide particles. For the first time, surface compositions were determined by using laser-ionization mass spectrometry (LIMS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Cationic and cationic species on the surface were analyzed to elucidate the phenomena. It was proven that these new techniques are very useful in understanding the basic mechanisms of a sulfide mineral-flotation system.

Jan 1, 1997

By James H. Barks

Exploration for ore deposits in southeastern Missouri in the 1950&apos;s resulted in the important discovery of lead, zinc, copper and silver in 1955. Further discoveries in the area led to the naming of the Viburnum trend. It has sometimes been referred to as the "New Lead belt" to distinguish it from older lead-producing areas to the east. As presently developed, the "trend" is 35 miles long, running north and south about 50 miles west of the Lead belt. Galena (lead) is the principal ore mined, with lesser quantities of sphalerite (zinc), chalcopyrite (copper) and silver recovered as economic by-products. The ore body is as much as 140 feet thick and 1,200 feet wide, and is found in the Bonneterre Dolomite (Upper Cambrian) at depths ranging from 700 to 1,200 feet. Since its discovery many companies have engaged in exploration and several major companies have developed new mines and constructed mills and a smelter in the area. The first mine in the Viburnum trend came on stream in 1960, but as more mines came on stream and others reached capacity, lead production increased to the point that the Southeast Missouri Lead district produced 432,576 tons of lead in 1970 to become the world&apos;s largest lead-producing region (Missouri Geological Survey and Water Resources, 1971). The Viburnum trend area with its rolling, heavily forested hills and numerous clear running streams is in the Clark National Forest of the Missouri Ozarks. Until the recent development of its mineral resources, the area was sparsely populated and nearly unmarked by the activities of man. Industrial development is almost certain to be accompanied by environmental changes. In a day of growing awareness of the need to preserve the quality of the

Jan 1, 1971

By B. Stewart, R. Li

Coal waste materials inhibit the direct establishment of vegetation due to adverse physical and chemical properties, particularly low water retention and high potential acidity. The Moss #1 coal refuse pile is located in Dickenson County, Virginia, and was idled in the late 1980s with little topsoil resources available for final closure. The refuse was acidic (Total S = 0.38%; pH = 3.6), black in color and high (70%) in coarse fragments. The refuse also had a low water-holding capacity (4.5% in < 2.0-mm fraction). A small plot experiment was established on the refuse pile to evaluate the effects of liming rates (50% and 100% of lime requirements) and topsoil thickness (15, 30 and 60 cm) on vegetative growth and leachate quality. Liming and topsoil amendment increased the surface soil pH from <4.0 to >6.0 over a two-year period, which resulted in greater vegetative cover and biomass than the control plots. All topsoil treatments resulted in greater vegetative cover and biomass than plots treated with lime only. This was due to improved surface soil physical and chemical properties. A topsoil treatment of 60 cm gave the thickest vegetative cover and biomass yield. Such a treatment, however, would be cost-prohibitive at this location. Applica¬tion of 27Mg ha`1 of lime to the refuse surface along with 15 cm of topsoil produced acceptable two-year vegetative cover and biomass, and this appeared to be the optimal treatment for this particular situation. Both liming and topsoil had no affect on leachate pH and the electrical conductivity of leachates collected below the plots. This suggests that surface revegetation will have little effect on the quality of water draining through the pile. Therefore, long-term water-treatment requirements may not be reduced by successfully revegetating the pile surface.

Jan 1, 2000

Coal waste materials inhibit direct vegetation establishment due to adverse physical and chemical properties, particularly low water retention and high potential acidity. The Moss # I coal refuse pile is located in Dickenson County, Virginia, and was idled in the late 1980&apos;s with little topsoil resource available for final closure. The refuse was acidic (Total-S = .. 38%; pH = 3.6), black, high (70%) in coarse fragments, and had a low water holding capacity (4.5% in < 2.0 mm fraction). A small plot experiment was established on the refuse pile to evaluate the influence of liming rates (50% and 100% of lime req.) and topsoil thickness (15, 30 and 60 cm) on vegetative growth and leachate quality. Liming and topsoil amendment increased the surface soil pH from < 4.0 to > 6.0 over a two-year period, which resulted in greater vegetative cover and biomass than the control plots. All topsoil treatments resulted in greater vegetative cover and biomass than plots treated with lime only due to improved surface soil physical and chemical properties. A topsoil treatment of 60 cm gave the thickest vegetative cover and biomass yield. Such a treatment, however, would be cost-prohibitive at this location. Application of 27 Mg ha-1 of lime to the refuse surface along with 15 cm of topsoil produced acceptable two-year vegetative cover and biomass, and appeared to be the optimal treatment for this particular situation. Both liming and topsoil had no affect on leachate pH and the electrical conductivity in leachates collected below the plots. This suggests that surface revegetation will have little effect on the quality of water draining through the pile, so long term water treatment requirements may not be reduced by successfully revegetating the pile surface.

Jan 1, 1999

By S. Tandanand

The Bureau of Mines, U.S. Department of the Interior, assessed the geological effects on the ratio of maximum subsidence and extraction thickness, hown as the subsidence factor, to develop a simple method for predicting the maximum subsidence. The study is restricted to the Northern Appalachian Coal basin where data were collected from 13 coal mines. A model previously developed to relate the subsidence factor with the lithology and with the width and depth of working panels was used in the assessment. The result shows the possibility of determining maximum subsidence without resorting to a rigorous method.

Jan 1, 1982

By Peter Zhang, Daniel Su, Heather Dougherty, Jack Trackemas

"Longwall mining has a significant influence on gas wells located within longwall chain pillars. Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings. If the gas well casings are compromised or ruptured, natural gas could migrate into the mine workings, potentially causing a fire or explosion. By the current safety regulations, the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars. The current regulations for the gas well pillar design are based on the 1957 Pennsylvania gas well pillar study. The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars. As the guidelines were developed for room-and-pillar mining under shallow cover, they are no longer applicable to modern longwall mining, particularly under deep cover. Gas well casing failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh coal seam. The study indicates that overburden depth and pillar size are not the only determining factors for gas well stability. The other important factors also include subsurface ground movement, overburden geology, and weak floor, as well as the construction of gas wells. Numerical modeling was used to model abutment pressure, subsurface deformations, and the response of gas well casings. The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above, within, and below the chain pillars, and the potential location and modes of gas well failures, therefore providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.INTRODUCTIONIn the eastern United States, abundant gas wells have been drilled through coal seams that are being actively mined by longwall mining. The existence of gas wells in the U.S. coal fields, whether active or abandoned, have caused many issues for longwall mining. First of all, any gas well in the mining area has to be located by all possible means. Secondly, the gas wells within longwall panels have to be plugged, as cutting through gas wells will allow natural gas to flow into the active longwall mines. On the other hand, the gas wells within longwall chain pillars or barrier pillars can be left in place if the wells are protected by properly designed pillars."

Jan 1, 2019