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By J. C. Fox, V. L. Ketellapper

The Summitville Mine, located in the mountains of Southwest Colorado, is an abandoned gold mine. From 1984 to 1992, Summitville was mined for gold using an open pit heap leaching technology. During this period, the volume of acid mine drainage released from the mine significantly increased. This was attributed to the development of the mine pits, the waste rock piles, the heap leach pad, and increased discharges from the drainage adit. The release of this acid mine drainage resulted in the destruction of the aquatic ecosystem for more than twenty miles downstream of the mine. Beginning in 1993, plans were implemented to reduce the amount of acid mine drainage released from the mine. The majority of this work has been completed at the mine. This work includes removal of the Cropsy Waste Pile, closure of the Heap Leach Pad, and revegetation of disturbed areas. Significant improvements to water quality downstream of the mine have occurred resulting from mine reclamation. Aquatic life has returned to portions of the previously mining impacted areas. This study discusses the actions taken to reduce the amount of acid mine drainage generated at the Summitville Mine, the costs of these actions and the resulting reduction in metal loadings. Over 250 samples taken at over 10 locations since 1993 form the basis of this evaluation. Copper loading is analyzed as an indicator of the effectiveness of the actions taken.

Jan 1, 2002

By D. F. Scott

The purpose of this study was to determine if miners are at risk from exposures to chemicals used in the mining industry, and determine the nature and sources of the illnesses and injuries. The authors reviewed the Mine Safety and Health Administration?s (MSHA) Employment and Accident, Injury, and Illness database and identified 2,705 cases of chemical-related injuries and illnesses that were reported to MSHA from 1999-2006, involving 66 different chemicals. The main source (cause) of chemical-related cases was acids/alkalis (about 39%). The primary nature (effect) of chemical-related cases was chemical burns (about 57%). The job classification where workers incurred the most chemical-related injuries and illnesses was cleaning plant operator/media operator/boney preparation plant operator/crusher worker. The number of nonfatal days lost did not change significantly and overall, the incidence rate of chemical-related cases decreased by 36%. Chemical burns accounted for a large number of injuries; mining companies should carefully examine their personal protective equipment (PPE) requirements, training methods, and safety culture to insure that their workers are protected.

Jan 1, 2009

By C. P. Mangelsdorf

Introduction The use of frequency of vibration measurements to determine tension has long been accepted by industries that use electrical or stranded cables of wire ropes in their operations. In contemplating how to determine the tension in chords of a roof truss, it seems almost inevitable that a similar approach should be investigated even though there are some important dissimilarities in physical behavior between a chord of a rod-type Birmingham truss and a stretched wire rope. While the dominant feature of both types of behavior is the existence of tension, the bending resistance of the vibrating truss chord cannot be ignored. And it is common to have attached to the chord, pieces of hardware (turnbuckles, extension sleeves, wedge boxes) that represent concentrations of mass not usually found in a vibrating wire rope. Analytical solutions to the problem of vibrating wires or beams can be found in the literature on vibrations (Timoshensko, 1955; Den Hartog, 1956). But in every case, at least one of the ingredients of the vibrating truss chord is missing. The presence of axial tension, or bending resistance, of concentrated masses and of end conditions peculiar to truss chords is a combination that appears not to have been dealt with before, although the techniques for dealing with it are commonly known. The purpose of this note is to report the results of a project to measure and calibrate such frequencies. The work was conducted by the University of Pittsburgh under the sponsorship of the US Bureau of Mines. Field observations Tests were conducted on 24 different truss installations. The first 18 trusses were installed in shale roofs above Kentucky No. 9 seam and Illinois No. 6 seam. The remaining six were placed against the competent sandstone over the Pocahontas No. 3 seam in West Virginia. Chord tension was determined by two electrical resistance strain gages, in series, applied diametrically opposite to one another on the rod before tensioning. Due to the combined effects of inexact gage placement, rod bending and residual torsion in the chord due to tightening, errors in tension as high as 1780 N (400 lb) were reasonably possible. Due to faulty soldering or damage, three of the first 18 trusses and one of the final six were rendered completely unreliable. In addition to strain, the first natural frequency of vibration was observed to the nearest 0.1 Hz. Dimensions recorded included the span between contact points at the bearing blocks (Fig. 1) and the locations and amount of excess rod and rod gap at the wedge box and turnbuckle, respectively.

Jan 9, 1985

By JOHN R. HEBERGER, MAHIYAR F. NASARWANJI, Jonisha P. Pollard, Lydia M. Kocher

nt in the mining industry, and identifying factors associated with these injuries is critical for developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011 to 2017. Hand and finger injuries occur at a rate of 6.53 per 1,000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53 percent) followed by bone fractures/chips (26 percent). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals — such as pipe, wire and guarding — and hand tools as the primary sources of hand and finger injury. Although the information on glove use was limited, leather gloves were most often worn when an injury occurred.

By E. Petrakis, K. Komnitsas

The main objective of batch grinding modeling is the estimation of the product particle size distribution over time or specific energy input to the mill. So far, the developed analytical methods require often complicated calculations which are timeconsuming. Thus, more simple approaches that allow the reliable prediction of the complete product size distribution need to be developed. In the present paper, an approach, based on the population balance model (PBM), that reliably predicts the product size distribution is proposed. In order to enable this, the simplified form of the fundamental batch grinding equation was transformed into the well-known Rosin–Rammler (R-R) distribution, thus allowing the determination of the breakage rate for each grinding period. A time-dependent breakage rate framework was developed where the traditional linear theory of the PBM is considered a partial case. This approach allows the deviations from the linear theory to be categorized and the degree of the acceleration-deceleration of the breakage rate to be predicted. Modeling results were validated by laboratory grinding studies using two homogeneous materials, quartz and marble, and one heterogeneous, a limonitic laterite. The experimental data revealed that grinding exhibits non-first-order behavior and the degree of deviation from the linear theory depends on the tested material. The reliability of the proposed model was validated with the use of the distribution modulus n, the a value of the breakage rate parameter, and the optimum n values that minimize the sum of the differences between the experimental and estimated particle size distributions.

Feb 8, 2021

By Timothy Batchler, Khaled Mohamed

Standing supports have been used in coal mines for decades to enhance roof support capability. Sometimes standing supports are used as a tool to resist the lateral movement of spalled ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) are conducting a testing program for different types of standing supports (steel and timber) to investigate the effect of lateral loading on their vertical loading capacities and the factors affecting their lateral loading capacities. In this paper, the mine roof simulator (MRS), at the NIOSH Pittsburgh research facility, was used to determine the response of steel props to vertical and horizontal loadings. Finite element models (FEMs) were developed and verified using the tested steel props. To justify the testing program for testing standing supports with end-conditions of rock-like materials, the verified prop models were used to study the effect of a wide range of roof and floor materials (gray shale, shale, and claystone) on the critical buckling loads of the steel props. Also, several lateral loading scenarios were evaluated in which the steel props were laterally loaded at different heights. The critical buckling load for steel props setting up against a claystone roof and floor was found to be one-half of that shown by the MRS test where roof and floor platens are made of steel. Minimum prop performance was observed when the lateral load was applied at the mid-height of the steel prop, especially at small lateral displacement (less than 2 in).

Sep 10, 2022

By M. Abdelkhalek, M. Hepworth, D. Tao, B. K. Parekh

Pre-combustion coal cleaning and post-combustion flue gas desulfurization (FGD) using lime or limestone are the primary methods employed to reduce sulfur dioxide (SO2) emission from coal combustion. These processes generate voluminous pyrite and gypsum solid wastes that are usually landfilled, occupying thousands of acres of land and creating serious land and water pollution problems due to the release of acids and toxic substances. An integrated process has been developed for the combined utilization of gypsum and pyrite wastes by converting them into useful products including lime, sulfur, and direct reduced iron (DRI). The process includes four major steps. The first step is to concentrate pyrite from coal preparation tailings using flotation or gravity separation. The second is the thermal decomposition of pyrite into pyrrhotite and sulfur. This is followed by the reduction of pyrrhotite with carbon in the presence of lime to produce iron and calcium sulfide. The fourth step involves the reaction of calcium sulfide with gypsum to produce lime. The chemical reactions involved in the process were studied using thermogravimetric analysis (TGA) and X-ray diffraction (XRD)techniques. Process variables studied included reaction temperature, time, reactant composition, and purity of reactants.

Jan 1, 2000

By L. K. Marshall

The importance of high quality underground mine ventilation is readily apparent. The principles of primary and auxiliary mine ventilation, however, are sometimes less readily apparent. The first article in this two-part series discusses some general aspects of primary and auxiliary ventilation. Next month's article will detail considerations involved with auxiliary mine ventilation.

Jan 1, 1982

By G. E. d’Aquin

Sources of sulfur have varied based on technology and societal needs. It has been mined in its elemental form for centuries. Twentieth century technology brought thermal mining (Frasch, 1894) to the forefront of sulfur extraction. Then, by the 1980s, petroleum processing generated almost 40 percent of the 50 Mt (55million st) of sulfur in all forms (SAF) produced in the world. Metals processing (the reclamation of effluent gas by various means as “sulfur in other forms,” or SOF) followed at 30 percent of all sulfur values produced and then Frasch at 22 percent. Petroleum and gas processing now generate most of the elemental sulfur produced in the world. Single Two Frasch mines remain, one each in Iraq and Poland. Conventional mining of small to insignificant volumes also survives in Russia, Latin America and Indonesia. The volume of “recovered” sulfur (the name commonly given by the industry to hydrocarbon-derived material) generated will increase faster than energy consumption as oil and gas with greater amounts of sulfur are used and environmental restrictions on the sulfur content of the fuel consumed become more stringent.

Jan 1, 2005

By S. K. Singh, J. Shepherd

"Feather edging"- a major source of injury and fatal accidents in Australia, South Africa and USA, refers to a phenomenon where the roof, at the goaf edge, falls as a thin wafer of rock often suddenly, over-riding conventional timber breakerlines. It may run down and affect adversely a working bord at distances of 15 metres or more from the goaf edge. Feather edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a mine trial where a concentrated row of fully grouted bolts were able to resist the feather edging in the first comprehensive, monitored trial in an Australian pillar ('total') extraction coal mine.

Jan 1, 1999

By R. J. F. Goodfellow

Many underground projects now include preparation of a Risk Register through planning and design as a tool for project and risk management. There is still significant discussion within the industry as to whether and how to best present the Risk Register through the bidding process and the construction phase of a project. While the ITIG Code of Practice for Risk Management of Tunnel Works recommends this approach of continuity in risk management procedures, it is silent on the specifics of how this should be achieved. This paper will explore the perceived benefits and disbenefit of including the project Risk Register with bid documents; format and content that should be transferred and lessons learned using the case history of bidding and early construction phase of the Bi-County Water Tunnel in Montgomery County, MD

By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By Trevor Ellis

The following is extracted from a report by the author to the International Valuation Standards Committee (IVSC), with minor modifications for the purpose of publication. The author represented the IVSC at the annual session of the Ad Hoc Group of Experts on Harmonization of Fossil Energy and Mineral Resources Terminology. This is a body organized by the United Nations Economic Commission for Europe (UNECE). This second session, held in Geneva, Switzerland, achieved an important agreement for advancement toward uniform global standards for the classification of minerals and petroleum reserves and resources. Attendees discussed the possibility of enhancing the United Nations Framework Classification for Energy and Mineral Resources (UNFC) for implementation globally as the classification standard for use in financial reports under the International Financial Reporting Standards (IFRS). Presently, there are between 100 and 200 mineral and petroleum resource classification (or definition) systems throughout the world — a similar number to what there are countries.

Jan 1, 2006

By S. J. Neethling

The flotation froth structure and motion determines the amount of entrained gangue that is collected to the concentrate. Despite this important role in the overall performance, the behaviour of the froth is still ill understood. To date, predominantly empirical models have been developed to describe entrainment. A fundamentally based model is described and used here in an attempt to improve the understanding of entrainment. This general froth simulator (UMIST FrothSim) allows the modelling of a wide range of flotation conditions, as it takes account of a large number of the physical phenomena that occur within flotation froths. The model firstly describes gas motion and bubble coalescence, and the water motion based on gravitational, viscous and capillary effects. The motion of the solids distinguishes between various solids classes based on hydrophobicity, particle size and density and models them by including the effects of Geometric and Plateau border dispersion, particle settling and the motion of the water. The aim of this paper is to show the applicability of this model to explain the observed entrainment and collection of gangue. This is done by comparing model predictions with the experimentally observed relationship between the gangue and water recoveries. The model predicts the identical trends, which are explained in terms of the interaction between the linear effects of water motion and hindered settling and the non-linear effect of particle dispersion.

Jan 1, 2001

By Jorge Armstrong, Sean Warren, JOSEF BOURGEOIS

The application of statistical analysis software programs has proven useful for the investigation of rockfall runout distance along a designed slope. Rockfall modeling programs are continually being upgraded with more sophisticated analysis tools, such as the use of the rigid body versus lump mass models. Engineers at mine sites utilizing the software may have varied experience related to these models, their associated input parameters, and how to interpret the generated results. To address this concern, researchers at the Spokane Mining Research Division (SMRD) of the US National Institute for Occupational Safety and Health (NIOSH) investigated the influence of slope height, slope angle, slope material, and rock size for both rigid body and lump mass models in a 2-D statistical analysis program. Based on a literature search and industry input, specific ranges common to that of an open pit mining environment were chosen for each of the input parameters to determine 90% rock runout distance as well as their sensitivity to change. Data collected from this numerical analysis and simulation will be compared to empirical rockfall data gathered through the duration of the Highwall Safety project conducted by NIOSH from 2022–2026.

Jun 18, 2023

By Dennis A. Swyt

In current post-industrial America, U.S. manufacturing is undergoing major changes both in the technology of its production and in the size and composition of its workforce. At the same time that computers and robotics move the shop floor toward becoming the unmanned "factory of the future" [1], they increase the need within the overall production enterprise for new types of technicians and engineering professionals [2]. Based on previous works which examined, first, the evolution of the technology of manufacturing toward the flexibly-automated factory of the future and, second, the technical- professionalization of U.S. manufacturing sectors [1,3], this paper looks briefly at the workforce of the U.S. metals industry.

Jan 1, 1989

Clean Diesels fuel-borne catalyst, Platinum Plus, helps improve fuel economy for all engines up to 10 percent while reducing particulate emissions by up to 25 percent. When used with a simple diesel oxidation catalyst, particulate emissions can be reduced by 30 to 50 percent. The use of Platinum Plus enhances combustion in the cylinder, burning fuel more completely. This reduces CO2 and other greenhouse gases and lowers total operating costs by improving fuel economy.

Jan 1, 2007

By Joseph Irons, David Westfall

Three rock tunnel sewer systems are underway in the Chicago Area. (Figure 1) The three are designed to act independently and to be later connected to the future tunnels of the master plan. The tunnel excavation for each of the systems has been completed. One is in the Northwest area within the City being built by the City, known as the Lawrence Ave. System. Another is in the Southwest suburbs, known as the LaGrange-Brookfield Sewer or Southwest 13A, being built by the Sanitary District, the third is in the South suburbs called the Crawford Avenue sewer or Calumet 18-E, Ext. A- being built as a joint venture between the City and the District. The three are similar in that they have the same purpose, the same component parts and their tunnels were constructed in the nigaran limestone using a mechanical mining machine. The purpose of each of the systems is two-fold. First to provide flood relief for existing inadequate sewer systems, and second to reduce the pollution load to the waterways caused by combined sewer overflows. The existing systems in the areas to be relieved are combined sewers built many years ago. The main outlet for the Village of LaGrange, for example, was built in 1908, is badly in need of repair and lacks the capacity to handle the flood flow from the heavily urbanized area it now serves. The dry weather flow from the area is taken off by intercepting sewers. However during

Jan 1, 1997

By T. Patten

A method for stabilizing mercury containing waste for landfill disposal would be a very cost effective solution for industry. A mercury polythiocarbonate material which is made via a metallurgical process passes a traditional TCLP for mercury. The mercury polythiocarbonate material was subjected to a more thorough evaluation, the Integrated Leaching procedures as described in Kossan (1) and Sanchez (2)The procedure involves leaching the mercury polythiocarbonate material at varying pH and sample size to liquid. The procedure had to be adapted for small sample sizes and finely divided materials due to the product characteristics and available material. The leachates were evaluated and found to be stable within common environmental pH values. The performance details on how Inter-Mountain Labs met the leaching requirements of the procedures and the analysis of mercury are presented.

Jan 1, 2012

Coal that meets customer specifications is often stored in silos before being loaded into cars. It is often found that coal in a particular car does not meet customer specifications due to the mixing of coal inside the silo. Some new contracts require meeting specifications on a per car basis. Silo flow models are used to predict quality in such cases. However, coming up with an accurate silo flow model for each case is very difficult and time consuming. This paper examines the viability of using an online analyzer at the loading end of the silo in conjunction with a feedback circuit, to optimize the quality of the coal being loaded into trains, so that each car meets quality specifications.

Jan 1, 2000