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By A. W. Khair

Surface subsidence is a phenomenon mainly associated with longwall mining, although it can also occur if the coal pillar left to protect the surface deteriorates with time and results in the collapse of the room and pillar system. A method has been developed that utilizes physical mine models and laser holographic interferometry. This method is capable of measuring displacements as small as 5 micro- inches by means of generating displacement contours on a surface, even that of granular materials. Analysis of subsidence in room and pillar mining using models of various extraction ratios ad overburden depths along with two different types of overburden model material (sand and gelatin) has been made. The sand represented the extreme brittle conditions of geologic material while the gelatin represented visco-elastic behavior of geologic material. This paper deals with the analysis of data which has been gathered up to date, and mainly associated with the use of sand as an overburden model material. The analysis included the effect of variation of geometric parameters on surface subsidence. Among these parameters are: variation in seam depth and thickness, surface and seam inclination, and extraction ratio.

Jan 1, 1984

By O. K. Brown

U.S. Borax has two tailings disposal requirements which are uniquely different in many respects, but with the common goal to minimize the impact on the environment, utilize dependable technology and minimize the economic impact. The existing borax mine in the grid Mojave desert of Southern California has gone through a series of changes in tailings disposal practices in the 56 years of operations, The other tailings disposal requirement is a new molybdenum mine, presently in the feasibility phase, in the high precipitation setting of Southeast Alaska. II. Introduction U.S. Borax is faced with two tailings disposals situations, at diverse locations:

Jan 1, 1984

By Charles C. Mosher

An in-mine seismic technique for detecting faults has been tested in a Western U.S. coal mine. This technique has been used extensively in the U. K. to help guide longwall mining operations. Explosives detonated on the face of a seam generate sound waves which propagate into the seam. Reflections from faults are picked up by sensors on the same face. Computer processing is then used to determine the fault locations. A known fault was successfully located in this test. Modifications to the U. K. procedures were required for the relatively thicker roan and pillar mines common in the Western U. S.

Jan 1, 1983

By Laszlo Valentyik

The wide scale acceptance of the heavy media separation is due to its simplicity and efficiency. The two most important variables of the process are specific gravity and consistency of the medium. The latter is a function of the settling rate of the media solids. The almost always present clay in the feed and conse¬quently in the medium acts as a stabilizing agent, and its optimum concentration varied between 3-4%.(1,2) Since polymers essentially perform the same function in oil well drilling muds - i.e. to suspend cuttings during drilling - as the fine clay in heavy media separation, this led to the investigation of whether polymers could be used in heavy media separation as supporting agents. During the first phase of the work, it was found that by the controlled addition of polymers, the stability of the heavy media increased without unduly increasing viscosity of the suspensions, thus yielding conditions for more effective and efficient separation. The results of the experiments were reported in a paper at the AIME Centennial Annual Meeting, March 1971.(3) This paper presents the results of the experiment carried out during the second phase of the work.

Jan 1, 1975

By St. Mergentime, K. Zeidler, V. Gall

2001, the New Jersey Transit Authority commissioned the JV Merco-Obayashi with the rehabilitation contract of the approximately 130-year-old, 4,200 ft long, partially brick- lined Bergen North Tunnel. The contract entailed the tunnel enlargement, shotcrete and rock dowels initial support according to the NATM, a waterproofing system, tunnel drainage and a cast-in-place concrete lining. The rock conditions encountered required design adaptations and significant modifications of the initial tunnel support. Flexibility, skill and extensive experience on the Authority’s and Contractor’s side finally lead to a success. This paper describes the operations and design modifications carried out.

Jan 1, 2003

By K. G. Colman

Este texto intenta facilitar al operador y contratista 10s datos básicos para dimensionar las cribas vibrantes que deban ser utilizadas en las plantas de trituración. Las capacidades básicas, factores que la modifican .... etc., utilizados en el cálculo de la superficie requerida, se han desarrollado empíricamente y modificados sus valores hasta el presente con 10s datos de las aplicaciones prácticas Hay que señalar que el cribado tiene mucho más de arte que de ciencia exacta; sin em- bargo, la información aquí presentada proporciona una razonable seguridad cuando se aplica al cálculo de cribado de minerales metálicos.

Jan 1, 1982

By J. A. Rusnak, K. M. Mohamed, M. A. Van Dyke, M. M. Sears, G. Rashed

"Researchers from the National Institute for Occupational Safety and Health (NIOSH) recently developed a coal-mass model to realistically simulate the deformation and loading behaviors of the ribs of coal pillars in underground coal mines. The scale-dependent properties (stiffness and strength) of coal material were considered in the coal-mass model. In this paper the orientation of face cleat with respect to driving direction was integrated in the coal-mass model. The controlling parameters (dimensionless coal-mass scale and fracture strains) of the modified coal-mass model were calibrated using a published case study of coal pillar strength. Numerical models with wide ranges of controlling parameters were conducted to simulate the test pillar. The best match between the numerical modeling results and the measured stresses and deformations was achieved by using a coal-mass scale of 30 and fracture plastic shear and tensile strains of 3.25% and 0.325 %, respectively. INTRODUCTION The failure of coal pillar ribs by itself are a major hazard in underground coal mines. Furthermore, failing ribs can indirectly contribute to roof and floor instability by increasing opening widths across intersections and entryways. Over the past decade, rib failures have resulted in 12 fatalities, representing 28% of the ground-fall fatalities in U.S. underground coal mines. Mining depth has always played a very important role in assessing rib stability. Gauna and Mark (2010) completed an analysis of rib fatalities that occurred between 1996 and 2010. One of their most prominent and influential findings was the identification of a relationship among fatalities, depth, and mining height. Therefore, Coal rib stability will continue to be a challenge for future deeper mines in U.S. coal basins. In the past several decades, research efforts have focused on roof support. The current rib control practice in U.S. coal mines is to select rib bolts through a trial-and-error approach (Mohamed et al., 2015a). Rib failure incidents can be can be substantially reduced or even eliminated by adopting an engineering-based coal rib design approach. The factors affecting rib stability in coal mines are numerous and mutually dependent. These factors include but not limited to mining height and overburden depth, interburden thickness for multiple-seam mining, coal strength, cleat density, entry direction with respect to cleat orientation, existence or absence of partings in the coal, percentage of extracted roof and/or floor rock, density of rib bolt support (Mohamed et al., 2015a). Moreover, it is difficult to isolate the particular effect of a specific factor on the overall rib stability. Therefore, a reliable empirical rib design approach is not achievable because it requires a significant number of case histories to be collected in order to have a reasonable range of all of the critical parameters. However, numerical modeling can be a practical tool to assist with rib support design if the modeling is realistic, which can only be achieved through calibration and validation of the numerical model against field data."

Jan 1, 2018

By G. Triantafillou

The aim of this paper is to present the progress of the plan of the Greek Public Power Corporation S.A. (PPC S.A.) at the Lignite Centre of Megalopolis in Peloponnesus (southern Greece) to manage impacts on local communities in areas affected by its activities during the lignite mining operation and post-closure. The reclamation works in the waste dump areas of the mines that constitute the Megalopolis Lignite Centre, concerning the utilization of waste dumps for infrastructure community projects constructions are discussed. Moreover, selected environmental indicators concerning land use and closure and rehabilitation are presented.

Jan 1, 2008

By J. E. Hoffman, Corby G. Anderson, T. J. Keefe, O&apos, Suzzann M. Nordwick

Antimony removal has become necessary as it is commonly found in precious metal refractory ore bodies. The Sunshine Mine in Kellogg, Idaho has recovered metallic electrowon antimony from its argentiferous tetrahedrite (Cu2S'Sb2S3) deposits for over fifty years. Recently, Sunshine conducted an intense research effort to improve and modernize its antimony facility. This paper presents information which was learned about the antimony electrowinning processes and the development of a single¬-electrolyte antimony electrowinning technology. The relevant effects of process variables were investigated. The research results and the relevant chemistries involved in metallic antimony electrowinning will be discussed.

Jan 1, 1993

By Ernst Raphael

Mechanical drives of belt conveyor drives have experienced a huge amount of improvements concerning technology, manufacture and product structure that reduced investment and maintenance cost significantly. Most of these improvements were of technological nature in the'70s and '80s of this century; whereas, the present decade requires products that meet technical excellence as well as commercial advantages such as quick delivery, low cost and reliable spare parts supply. The best approach to meet these requirements is a highly modular and standardized system of reliable components that cover all demands a conveyor drive might require.

Jan 1, 1998

By Nagashi Ogushi

Geochemical prospecting method using stream sediments, soils and rock chips has been tested to see the applicability for the typical Kuroko field in Japan. Three independent anomalies have been detected in maps being shown by grav densities of cells which are represented by the results of factor analysis as well as distribution of minor elements scaled in logarithm. A small vein type mineralization which has outcrops could be attributed to the origin of them whereas the one near the surface of known Kuroko deposit to a coincidence. The addition of drill core geochemistry is required to complete the interpretation.

Jan 1, 1982

By Arpad E. Torma

The electrochemical behavior of a zinc sulfide concentrate during the microbiological leaching was investigated using ZnS-carbon paste electrodes and a cyclic voltametric technique. The effects of Zn2 [ ] , Fe2+, Fe3+ and Cu2+ on the cathodic and anodic currents associated with zinc sulfide leaching in presence and absence of microorganisms, were assessed. The semiconductor nature of zinc sulfide was discussed in terms of ability of microorganisms to obtain their metabolic energy (through removal of electrons) from this high energy gap substrate. The intermediate electrochemical reactions involved in the ZnS leaching were described.

Jan 1, 1989

By K. E. Harrison

The acid rain legislation has passed into law. This new law has caused the power generation community to investigate alternative methods to obtain compliance with the new legislation. One thing all of the power companies have concluded is the answer is not easy. Do we switch fuels to burn all low sulfur compliance coal? Maybe possibly only partial desulfurization by means of a dry sorbent system? Or, finally, maybe a wet scrubber system? Whatever the choice, the power community needs to investigate all of the alternatives. In 1988, ICF Kaiser Engineers, Inc. (ICF KE) responded to a request by the U.S. Department of Energy for the engineering development of advanced physical fine coal cleaning. ICF KE responded and was awarded a contract to conduct a multi-task program to develop an advanced flotation system to eliminate pyritic sulfur and retain as much energy as possible. ICF KE assembled a team that included members of industry, academia, and industry research organizations to conduct this multi-task program. The program includes sixteen (16) tasks. This team had personnel to help solve some of the anticipated problems and to provide industry prospective on the viability and commercial potential for any concepts proposed. The primary team consists of a major coal producer, Babcock and Wilcox, Eimco Process Equipment Company, and Virginia Polytechnic Institute and State University.

Jan 1, 1992

By D. M. Muir

Thiosulfate offers a nontoxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32; It is shown that an understanding of the copper speciation and sulfur speciation is required to optimize this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2002

By S. J. Schatzel, K. M. Ajayi, E. N. Rubinstein, Z. Khademian

This study simulates the impact of a shale gas well casing breach near a longwall mine. Field studies are conducted to measure mining-induced permeability changes over the abutment pillar of a longwall mine, and a geomechanical model is developed in 3DEC, a three-dimensional numerical modeling code, to predict the aperture of fractures in the overburden at the study site. The predicted aperture values are used to determine mining-induced permeabilities, and the results are compared with the field measurements. These aperture values are provided as inputs into fracture flow code (FFC), which generates a stochastic discrete fracture network (DFN) model for the study site and predicts the potential shale gas flow to the mine. Results from 100 DFN realizations are statistically analyzed using the bootstrapping method to compensate for notable variation in fracture geometry. The results show a significant difference between the gas inflow for nearby panels due to increase in the induced permeability during mining of the second panel. The average gas flow to the mine was calculated as 4.72 × 10 m3/s (49 cfm) for a hypothetical breach at the Sewickley horizon during the first panel mining, 8.97 × 10 m3/s (19 cfm) for a hypothetical breach at the Uniontown horizon during the first panel mining, 2.16 × 10 m3/s (458 cfm) for a hypothetical breach at the Sewickley horizon during the second panel mining, and 8.07 × 10 m3/s (171 cfm) for a hypothetical breach at the Uniontown horizon during the second panel mining. Depending on the mine ventilation system, this could result in methane concentrations exceeding regulatory limits. Hence, these findings provide insights into the potential risk of an unconventional gas well casing breach near a longwall mine under shallow cover.

Feb 1, 2024

By Todd S. Harris

Industrial minerals or non-metallic minerals are loosely used terms applied to a diverse assortment of materials which, in many cases, have nothing more in common other than the fact that they are neither metals nor fuel minerals. To help bring order to this otherwise random assortment of minerals, we have grouped these materials into two main categories; chemical and physical minerals, and nine sub-categories based on end-use applications as shown in Table 1. Chemical minerals are products which are principally used for the specific chemical elements they contain, whereas physical minerals are products which are used to meet specific performance specifications. The latter part of the 1970?s, in particular 1978, were considered peak years in terms of production and sales for many industries, By using 1978 as a base year, we can evaluate wherethese markets stand today after the recession of the early 1980's and the recovery which began several years ago. From this historical overview and appraisal of the current situation, various assumptions can be drawn as to which markets are expected to perform well into the 1990's.

Jan 1, 1987

By M. C. Mound, L. Fradette, C. Colbert

Metallurgical Accounting in the mineral processing industry transforms accumulated process data, including flow rates and assays, into a coherent information format. This is used to rapidly provide production reporting and key performance indications. A fully comprehensive and coherency of available data must be a component of any system expected to accomplish reconciliation in the mass balancing process. Quality issues are thus improved with such desired methods via a mass-balancing engine utilizing the results of measurements acquired by various on-line sensors, analyzers, and sophisticated laboratory equipment. Metallurgical Accounting, when accomplished through such an engine, provides high value information in a simple, straightforward, and simplified manner. Exceptional utility is then transparently available to authorized personnel for access to metallurgical accounting reports, production reports, mass balance results, performance indicators, and so on. This paper discusses how such information can be used to "drilldown" into each result set by consulting the data hierarchy to evaluate and validate calculations and input data used to produce the specific results being queried. The power of such a system resides in the full and true integration of all production and laboratory data. What is integrated are the data thus acquired via a single user interface, a single database, a single configuration tool, etc. From this comes the derivation of contextual information and its maintenance. It is possible to reduce metallurgical accounting and production reporting from possibly hours or even days to a matter of minutes. The result is maximization of information reliability and availability from masses of otherwise discrete and difficult to access key data.

Jan 1, 2003

By A. D. Davis, C. J. Webb

Brohm Mining Company's Gilt Edge Mine in the northern Black Hills was a surface heap-leach operation that was active from the 1980s until 1999. Financing problems and acid drainage concerns at the mine were reported in the late 1990s. In February of 1999 the Governor of South Dakota announced plans to request the U.S. Environmental Protection Agency to help clean up acidic water at the mine and reclaim the site. In July 1999 the parent company of Brohm, Dakota Mining, filed for bankruptcy in Canada. Because of the bankruptcy and environmental problems, the State of South Dakota intervened and began water treatment. The mine was declared a Superfund site in 2000. Hydrologic issues include the potential for acidic drainage from the site. The mine is at the headwaters of Strawberry Creek, which drains into Bear Butte Creek. About four miles downstream, Bear Butte Creek loses its discharge to swallow holes in the karstic Madison Limestone aquifer, a regionally extensive and valuable ground-water reservoir. Other concerns at the site include treatment of acidic water in mine pits and a waste rock dump.

Jan 1, 2002

By L. R. Shotwell, C. F. Voss, R. J. Bastian

Pacific Northwest Laboratory (PNL) currently supports the U.S. Department of Energy's Office of Civilian Radioactive Waste Management in developing and evaluating analytical methods for assessing the suitability of sites for geologic disposal of high-level radioactive waste. The research includes consideration of hydrological, geomechanical , geochemical , and waste package components and the evaluation of the degree of coupling that can occur between two or more of these components. The PNL effort and those of other research groups investing potential waste sites in the U.S. and abroad are producing a suite of computer codes to analyze the long-term performace of the proposed repository sites. This paper summarizes the ongoing research in rock mechanics at PNL involving flow through jointed rock. The objective of this research is to develop a methodology for modeling the coupled mechanical-hydrological process of flow through joints and then attempt to validate a "simple" model using small -scale laboratory test data as a basis for judging whether the approach has merit. This paper discusses the laboratory tests being conducted to develop s joint behavioral constitutive model for the numerical method under development and the modeling approach being considered.

Jan 1, 1986

At the dawn of the computer age in the early 1950's, few people in either the minerals industry or the field of electronic data processing (EDP) would have predicted the tremendous impact that the computer has had on the way we conduct our everyday lives and businesses. Herman Hollerith himself (see next page), the Columbia University mining engineer 'turned statistician who developed the first punched card electronic tabulating machines for the US Census Office in the late 1880's, would doubt- less be amazed at the progress that has been made in the application of data processing techniques to nearly all aspects of the mining cycle (Aul, 1974). More than any other factor, the availability of economical computing equipment has led the way for the development of the broad range of mining computer methods described in this text. While limits have been identified for many of the technologies commonly in use today, new technological advancements point to continued exponential advancements in computing price-performance in the 1980's. With those advancements, we may look forward to continued expansion of the role computers will play in mineral production.

Jan 1, 1979