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By Lawrence Adler

The design of an underground opening involves the coincidence of two highly complex and poorly specified components. First, the structural or mechanical characteristics of a geologic rock mass are not only extremely variable but are also very difficult to evaluate. Second, the general lay¬out of mine workings contains a large degree of indeterminancy as to the structure itself as a result of the indefiniteness of the mining process, and also because of the inherent redundancies associated with bulky and weighty structures. Even for the relatively simple problem of tunneling this complexity is well recognized to be "without question that to which the study of geo¬logy (for the Engineer) can most fitly and usefully be applied".1 It can, therefore, be appreciated that the comprehensive opening design problem involves a complicated assemblage of component structures made up of a sketchily defined, or sometimes even an undefined material and acted upon by largely unknown tectonic forces.

Jan 1, 1968

By W. G. Miller

A series of computer programs for the analysis and mapping of coal-related data has been developed at the Illinois State Geological Survey; these programs, known collectively as the Coal Data System, represent the latest achievements in computer processing of geologic data at the Survey. Building upon programs previously developed in the Survey's Computer Services Unit, they expand the scope of the computerized data base that the Survey has been using for analyzing coal-related data. The System was partially developed during a joint study by the Illinois State Water Survey and the Geological Survey entitled, ?Coal and Water Resources for Coal Conversion in Illinois.? 2 In that study the available coal reserves more than 42 inches thick in the two principal coal seams throughout the state were mapped. The System was used to calculate the coal reserves and to report the average number of tons of coal in place per square mile in each township (Figures 1 and 2). It also produced maps of the coal features of sufficient quality to be printed on material that was scribed as master copy for the printing of full-color 1:500,000 scale maps (see Figures 3 and 4).

Jan 1, 1975

By Z. Sartowski, M. J. Pearse

The authors present laboratory and plant results illustrating the benefits to be gained by using chemical additives, namely flocculants and surfactant dewatering aids, in the Bayer process. Advantages of synthetic flocculants over starch are illustrated in terms of more efficient solid/liquid separation in both the initial settling of blow-down slurries and in the CCD wash train. In addition, it is shown that the use of synthetic flocculants considerably reduce the levels of organic contaminants present in the process liquor. Secondly, very significant improvements in moisture removal were obtained by the application of dewatering aids to hydrate filtration/ washing operations.

Jan 1, 1984

By Xiaoting Li, Richard Adasiak, Benjamin Mirabile

Pumpable J-Crib stopping walls and Jennmar high-strength (HS) stopping panel walls are widely used for resisting high-ventilation air pressures and roof support in underground mines due to their installation efficiency, convergence allowance, and better performance than traditional concrete block stopping walls. Based on the different entry dimensions and required maximum ventilation air pressures of up to 36-in. water gauge, 24-, 27-, 30-, and 36-in.-diameter pumpable J-Crib stopping walls, or 18- to 30-in. thick Jennmar HS stopping panel walls can be designed, and their support capacities and convergence allowances are evaluated for better roof control. Pumpable J-Crib stopping walls consist of 0.187-in.-diameter steel wire reinforced, JCrib material-filled bags, and non-wire-reinforced filler bags in between. Jennmar HS stopping panel walls consist of two, 20-gauge (0.04-in.-thick), galvanized, cold-formed steel panels with J-Seal materials pumped in between. Based on the fundamental structural design principles and specifications of ACI 318-19(22), the compression and flexural strength, and shear resistance of the walls can be checked to be compliant with the codes and specifications following the load and resistance factor design (LRFD) method. Specifically, the 0.187- in.-diameter steel wires in the pumpable J-Crib walls and 20-gauge steel panels in the HS stopping walls are integral parts of the walls and are considered to effectively confine the J-Crib or J-Seal materials. These steel elements play a significant role in reinforcing and improving the strength or support capacity of the stopping walls from a structural design perspective. Because of the high ductility of low-density J-Crib/J-Seal materials and steel elements, these walls are good at accommodating or absorbing the roof convergence (≥5% entry height), which cannot be matched by a traditional concrete block stopping wall (Figure 1). Based on the successful design and application of these stopping walls in different mines for improving roof stability and avoiding the air leakage, the authors have formulated the design methodology and verified independently by the finite element analysis (FEA) simulation technique. This design methodology combines the fundamental structural design principles with specific wall dimensions and material properties, facilitating mine engineers and government agencies to understand the in-depth working mechanism of these stopping walls.

Jul 1, 2023

By D. W. Jahn

Road construction in the near future will require contractors to guarantee that a project will remain trouble free for years after the project has been completed. These guarantees will challenge aggregate producers to become technically proficient in judging performance of their products. Testing procedures are described that may be used to predict performance of concrete and asphalt pavements before being committed into a construction project, and may also be used as quality assurance tools during construction to monitor performance as construction proceeds.

Jan 1, 1995

By S. S. SHINDE, P. C. JIKAR, N. B. DHOKEY

Mill scale is an oxide waste product of the steel mills, which contains around 70% iron and other allied impurities. In the present context, a dynamic prototype counter current reactor (CCR) has been used for experimentation and simulation of particle bed by using discrete element method (DEM). Mill scale was pulverized to ASTM mesh range 140 (106 μm)/ + 270 (53 μm), and then it was oxidized in CCR to make single oxide Fe2O3 phase by maintaining required thermodynamic conditions such as pure oxygen at 1100 °C. Then this oxidized powder was subjected to reduction reaction in CCR having gas mixture ( H2:N2) ratio of 1:4 at 875 ± 5 °C for filling degree (fd) and reactor revolution (ω) ranging from 5.38 to 16.14% and 2 to 5 rpm, respectively. A creeping fluid flow condition (Re ˂ 1) and natural heat convection (Gr/Re2 ˃˃ 1) has been maintained while undergoing solid–gas reaction. Besides particle bed behavior has been quantified by Froude number (Fr) for the optimum operating window. The simulation was validated by the experimental results of reactor reaction product by X-ray diffraction (XRD) and scanning electron microscope (SEM) images. Prevailing heat transfer mechanism and reduction reaction mechanism has been established for solid–gas counter current conditions.

Nov 22, 2021

By I. E. Perera

Experiments were conducted to evaluate the response characteristics of commercially available gas, smoke, and flame sensors to fires of common combustible mine materials. The experiments were conducted in the large-scale Fire gallery located at the National Institute for Occupational Safety and Health (NIOSH) Lake Lynn Laboratory (LLL) in Fairchance, PA, using Ponderosa Pine, Red Oak, Douglas-fir, high and low volatile coals, PVC and SBR conveyor belt, No. 2 diesel fuel, and diesel exhaust. All the experiments (except those using No. 2 diesel fuel and the diesel exhaust tests) were conducted in a similar manner, with combustible materials heated rapidly by electrical strip heaters producing smoldering fires that quickly transitioned into flaming fires. The sensors included a diffusion-type carbon monoxide (CO) sensor, photoelectric- and ionization-type smoke sensors, a video smoke/flame detector, and an optical flame detector. Simultaneous measurements were obtained for average gas concentrations, smoke mass concentrations, and smoke optical densities in order to quantify the levels of combustion products at the alert and alarm times of the sensors. Because the required sensor alarm levels are 10 ppm and 0.044 m-1 optical density for CO and smoke sensors, respectively, the different sensor alarms are compared to the time at which the CO and smoke reached these alarm levels (1). In addition, the potential impact of using smoke sensors that have met the performance standards from accredited testing laboratories is also evaluated using the response of an Underwriters? Laboratory (UL)-approved combination photoelectric/ionization smoke detector. The results are discussed relative to fire sensor needs that can have a positive impact on mine fire safety.

Jan 1, 2012

By Wang Hongwei, Wu Yongping, Cao Peipei, Jiao Jianqiang

Fully mechanized top caving mining of steeply inclined extra-thick seams with variable angles has complex roof rock movement, failure, caving, and filling mechanisms. Moreover, the variable-angle coal seams make rock–equipment stability control challenging. We analyzed rock deformation and failure mechanisms, overburden bearing structures, and working characteristics of supports through physical simulations, field tests, and theoretical analysis of the no. 120210 working face of Zaoquan Coal Mine. Overburden rock movement has distinct regional characteristics, with a large caving height (to the main roof layer) in the upper area, and lower caving height (to the lower main roof) in the lower area. Support loading is regional and unbalanced along the inclined direction. The critical layer of overlying strata migrates, and bearing structures formed by breaking the critical layer exhibit cross-layer generalization along the inclination. The upper region has a cantilever beam structure in the basic roof rock layer; the lower region has an inclined masonry structure with multistage ladders in the breakage basic roof rock layer. Application of a false-inclined working face layout with the tailgate ahead of the headgate and an arc arrangement (radius 28.65 m, arc length 10–20 m) in variable angle areas, and regional control of support working resistance and top-coal caving amounts, control regional failure overburden. Safe and efficient mining was achieved, with the monthly production and recovery rates reaching 344,900 t and 85.86%, respectively. Our results expand the scope of fully mechanized top caving mining and have important theoretical and technological significance.

Nov 23, 2020

By J. M. Smith, T. R. Horton, R. L. Blanchard, T. W. Fowler

INTRODUCTION Uranium mining operations release radioactive materials into both air and water and generate large quantities of solid wastes containing low levels of radioactive materials. Solid wastes produced by mining operations remain on the surface at many inactive mining sites in the Western United States. These mining effluents may present a potential health and environmental hazard. Therefore, Congress, in Section 114(c) of the Uranium Mill Tailings Radiation Control Act of 1978, instructed the Administrator of EPA to prepare a report identifying the location and potential health, safety, and environmental hazards of uranium mine wastes and to recommend a program to eliminate these hazards. Several facts and limitations helped shape the method and approach of the EPA study. Little information on uranium mines was available; measurement information that was available on uranium mine wastes was frequently influenced (biased) by nearby uranium mills; time and resources did not permit comprehensive field studies to provide additional data; and there are inherent variations between uranium mines and sites that complicate generic assessments of mine wastes. To accommodate these facts, the EPA developed conceptual models of uranium mines and made health and environmental projections from them. The models were based upon available data from the literature, supplemented with information from discussions with persons inside and outside the EPA, and by doing several short-term field studies in Texas, New Mexico, and Wyoming. When necessary, conservative (maximizing) assumptions were employed. This paper presents a brief account of a part of the EPA study dealing with the potential health and environmental effects caused by active surface and underground uranium mines. Airborne contaminants are emphasized, although solid and liquid effluents are also included. Due to the limited space, only the methods and parameters used and the results of the assessments will be presented here. Anyone interested in the source of the data used and the development of the parameters should refer to the EPA report (Blanchard et al., 1981). The occurrence and emissions of stable elements were included in the EPA report, however, due to space limitations and their apparent small impact, except for possibly at some specific mines, only radioactive sources will be included in this presentation. MODEL URANIUM MINES The model surface mine was located in the South Powder River Basin of Wyoming and the model underground mine was located in the Ambrosia Lake area of New Mexico. These are the prevalent type mines in those areas. The model mines were based on the average production parameters of the 63 open pit mines and the 256 underground mines that were operating in the United States in 1978 (Department of Energy, 1979) and on a report of an extensive study of open pit mines in Wyoming (Nielson et al., 1979). Information contained in environmental impact statements and in reports from federal and state agencies was also used. Parameters for the model mines are listed in Table 1. The surface mining scenario is that 7 pits are opened in the 17-year mine life with overburden from each successively mined pit used to backfill a previously completed pit, resulting in an equivalent of one pit of overburden (2.4 year production) stored on the surface. No backfilling is assumed at the underground mine. Overburden or waste rock, ore, and sub-ore are separated into separate piles that are either rectangular in shape with length twice the width or in the shape of a frustum of a regular cone. Both shapes have 45 degree sloping sides. To account for bulking, the volume of the material comprising the piles was considered to be 25% greater than the volume of material removed from the ground. It was assumed that dewatering was required at both mine sites. Wastewater discharge rates at the surface and underground mines were assumed to be 3.0 and 2.0 cu m per min, respectively. SOURCE TERMS The following radioactive contaminants at active uranium mines were assessed in the EPA report: 1. Radioactive particulates in a) wind suspended dust from waste rock (overburden) pile, sub-ore pile, ore stockpile, b) suspended dust from mining activities (rock breakage, loading and unloading ore and wastes), and c) vehicular dust, 2. Rn-222 emanation from waste rock (overburden) pile, sub-ore pile, ore stockpile, and mining activities, 3. Rn-222 emanation from mine surface areas, and 4. Radionuclides in wastewater discharged to land surface. Estimated average annual dust emissions (item 1 above) from the model mines are listed in Table 2. Emission factors and the assumptions used to estimate these dust emissions are described in detail in the EPA report. Radioactive source terms were computed for each of the sources; dust emissions were multiplied by the concentrations listed in Table 1

Jan 1, 1981

By P. Maraboutis

Extractive industry (mining and quarrying operations), as other industrial activities, is subject to environment protection laws, regulation and standards such as the Environmental Impact Assessment directive, Natura 2000, Habitats & Birds directive, Water Framework directive etc The European Commission (EC) is aim to strengthen the EU environmental legislation to improve the (environmental and human) safety of mining activities. The mineral processing and the management of the mining waste will be covered by the new amendment of the Seveso II Directive, by a Best Available Techniques reference document (BREF) describing the Best Available Techniques of mining waste management and a new directive on the mining waste management. At the same time initiatives as the environmental liability, the energy taxation for environmental reasons and the natural resources management policy, which will have a positive impact on the protection of the environment, will affect the extractive industry operation procedures.

Jan 1, 2002

By Milton Gomez, Nico Sutmoller

Low-density cellular concrete (LDCC) was first introduced to the market in the early 1900s and since then has made continuous technological advances. There are two primary types of LDCC: permeable and non-permeable. Both types of cellular concrete offer advantages in different types of geotechnical engineering applications. Because of its unique characteristics of low density, high compressive strength, and high fluidity during placement, LDCC offers an effective solution for a wide variety of engineering applications, and in many cases provides a more cost-effective, labor saving alternative to traditional fill materials. This paper will review the history, characteristics, and technological advances of LDCC, highlighting multiple real-world case studies that showcase the high-performance capabilities of both permeable and non-permeable LDCC.

Dec 1, 2022

By F. M. Doyle, S. Duyvesteyn, K. Sreenivasarao

Toxic metals entering surface or ground water from sources such as metal finishing shop spills and abandoned mines can pose a significant threat to public health and the environment. Ion flotation and similar foam separation techniques show great promise for treating dilute, metal-contaminated solutions, and could also be used to treat effluents from many minerals and metallurgical processing operations prior to discharge. In ion flotation, an appropriate collector is added to the solution to form hydrophobic complexes with the metal ions. These metal-bearing species are then removed by flotation, usually with trace addition of a frother to stabilize the foam. In an effort to better understand the underlying scientific and engineering principles that determine the performance of ion flotation, the removal of Cu(II), Pb(II), Cd(II), Cr(II) and Cr(VI) has been studied using laboratory scale flotation columns in batch mode. The effects of the superficial air velocity, solution and froth height, nature of the collector, collector: metal-ion ratio, ionic strength and several frothers at low concentrations on the flotation kinetics are reported. Finally, results are presented on methods that might allow regeneration of collector and recovery of by-product metal from the foam product.

Jan 1, 1995

By Henning R. Norbom

Lime has been produced for many centuries. The simple pot kiln was one of the first devices used in this process. It was constructed of stone often on the side of a hill to reduce construction efforts and provide easy access to the top for feeding of limestone. It was fired from below with wood and coal. The pot kiln was very small and operated on the batch principle. The kiln being cooled between each batch, the fuel consumption was horrendous. The lime quality was poor with perhaps only one half of a batch being lime of suitable quality. Of the remaining half one part would be over burned and another part underburned. For centuries the lime burning technique was improved at a barely recognizable rate. One of the first major steps forward was the introduction of the continuous process vertical lime kiln. Although at first crudely constructed, the kiln had a refractory lining. It was charged with alternate layers of limestone and solid fuel usually in the form of coke. Continuous mode of operation, larger unit size and better heat distribution resulted in greatly improved fuel economy. However, quality of lime produced still left much to be desired. One problem was contamination by ashes from solid fuel.

Jan 1, 1978

By P. Rusin

A new bacterium, Thiobacillus cuprinus, can extract copper from chalcopyrite as rapidly as T. ferrooxidans. On solution with and without nutrient amendments and bacterial growth media were supplemented with T. ferrooxidans or T. cuprinus in shake flask studies. Both species extracted -42% of the copper using growth media. In one case, T. cuprinus solubilized approximately twice as much copper as T. ferrooxidans utilizing a seeded On solution. Thiobacillus prosperus also oxidizes chalcopyrite and tolerates high chloride concentrations. These sulfide-oxidizing bacteria are representatives of the mixed microbial community found in sulfide dumps. Rates of biological copper extraction from sulfide ores, using the native microbes, have been significantly enhanced by amending On solution with PGM.

Jan 1, 1994

By Caroline L. Herzenberg

Recently, neutron-induced gamma spectrometry has been introduced and gained provisional acceptance as a method for continuous automated analysis of coal. Instrumentation based on this technique has been under development for and in testing at coal preparation plants and a coal gasifier. To provide a deeper understanding of, and extended capability in applying this method, theoretical calculations have been performed of the absorption of thermal neutrons by various coal compositions, and the thermal neutron capture prompt gamma emission spectra produced by these compositions have been calculated. Selected results of these computer calculations and the computer generated spectra are presented.

Jan 1, 1984

By V. C. Kelessidis

Demand for multifunctional drilling fluids continuously increases. In the quest for more hydrocarbons, drilling has extended to deep water areas (now in excess of 2.000 m) and to very deep wells (now in excess of 6.000 m). In these extreme conditions, low temperatures, as low as 1-5°C on the sea bed, high temperatures, in excess of 200°C, and high pressures, more than 1.000 bars, in the bottom of the well, are frequently encountered. In these harsh environments, synthetic oil and oil based drilling fluids are used, but the former are expensive while strict environmental requirements have limited the use of the latter. Thus, drilling industry has turned back to water based drilling fluids which use bentonite as primary viscosifier and as a fluid loss control additive. However, in conditions of high temperatures, bentonite suspensions gel and loose their exceptional low temperatures properties, thus, additives are needed to overcome such problems. In this article we review these challenging drilling environments and establish the requirements for the multifunctional drilling fluids. Our research indicates that demand for continuing use of bentonite by drilling fluid industry is strong. Furthermore, we bring forward the opportunities for new additive development which can expand the operational ranges of bentonite suspensions.

Jan 1, 2007

By T. J. DeMull

AMAX's Sleeper Mine uses conventional cyanidation milling and heap leaching techniques to produce gold. Since milling operations commenced in March 1986, average ore processing rates have improved from the design rate of 455 tonnes per day to more than 720 tonnes per day. Heap leaching was added to the process facilities in September 1986 at a design rate of 1,500 tonnes per day, and current heap leaching rates exceed 2,680 tonnes per day. Presented are descriptions of the Sleeper processing facilities with emphasis on the crushing and grinding circuits, a review of the selection of crushing and grinding equipment, and a summary of operating performance during the first 16 months of operations.

Jan 1, 1988

By Daniel H. White

Block caving, unlike most other conventional forms of mining relies principally on the natural forces within the rock mass to fragment and transport the ore. Obviously, not every orebody can be satisfactorily mined by block caving. In the early stages of mine planning an attempt should be made to assess the benefits of the block caving system relative to others, and develop a reasonable mining concept that may be used to provide preliminary information to mine planners and financial specialists. It is the intention of this paper to outline some basic geotechnical parameters that are essential to: 1) Assessing the feasibility of block caving an orebody and 2) Providing semidetailed information relative to mine design based on drill hole and other data.

Jan 1, 1979

By S. W. Cavender

The analysis of the results of metallurgical experiments is often complicated by experimental errors and uncertainty, the complexity of the system being studied, and the confusion of correlation with causation. Consequently, comparative statistics are used to determine if a difference exists between the outcomes of tests, an estimate of this difference, and the precision of the estimate. This paper reviews the use of significance tests and confidence intervals for the comparison of results from two tests, the use of reference distributions, and blocking and randomization techniques to reduce unavoidable sources of variability. These techniques are demonstrated using plant and laboratory data.

Jan 1, 1993

By Armando Correa de Araujo

Cationic flotation of quartz is currently utilized for the concentration of iron ores and for the cleaning of phosphate concentrates. The present work deals with depression of quartz in the presence of aluminum ions during cationic flotation. It was established-that aluminum ions depress the flotation of quartz with an amine, especially under neutral and very slightly alkaline conditions. Studies of adsorption of Al ions on the quartz surface as a function of pH correlated with depression of this mineral with an amine as collector. The presence of Al ions also enhanced the depressant action of corn starch on quartz The sodium salt of ethylenediaminotetra-acetic(EDTA) was found to be an effective complexing agent to supress the depression caused by aluminum ions.

Jan 1, 1984